Asymmetric Cuts In The Contour Method For Residual Stress Measurement

The standard contour method is limited to sectioning test components into two symmetric halves. In this study a new approach is developed to deal with asymmetric cuts in the contour method of residual stress measurement. The proposed approach is demonstrated using finite element (FE) simulations and is validated experimentally using a series of asymmetric contour cuts and neutron diffraction measurements

Evaluation of a self-equilibrium cutting strategy for the contour method of residual stress measurement

An assessment of cutting-induced plasticity (CIP) is performed, by finite element (FE) prediction of the plastic strain accumulation along the cut tip when the EDM wire sections the NeT TG4 weld benchmark specimen along two cutting directions. The first direction corresponds to a conventional (C) cutting strategy, whereby the EDM wire cuts through the thickness of the weld specimen and travels in a direction transverse to the weld. The second direction corresponds to a self-equilibrating cutting (SE) strategy, whereby the EDM wire cuts across the transverse direction of the weld specimens and travels through the thickness of the plate. The cutting thus progresses simultaneously through the compression-tension-compression regions of present weld residual stress (WRS) field. This type of cutting strategy is believed to minimize the CIP by minimising residual stress redistribution during cutting, due to stress equilibration across the sectioned material. The simulated cutting procedures are conducted under a range of clamping conditions to assess whether mechanical restraint has a primary or secondary influence on CIP accumulation. Both predictions of CIP and the resultant back-calculated WRS demonstrate that (i) mechanical restraint is the primary variable influencing CIP development, and (ii) under no circumstance does a self-equilibrating cutting strategy perform significantly better than a conventional cutting approach. The reason that self-equilibrating cuts are not effective is illustrated by calculating the Mode I (KI) stress intensity factor (SIF) along the cut tip, and correlating trends in KI to CIP development

Investigating optimal cutting configurations for the contour method of weld residual stress measurement

The present work examines optimal cutting configurations for the measurement of weld residual stresses (WRS) using the contour method. The accuracy of a conventional, single-cut configuration that employs rigid clamping is compared with novel, double-embedded cutting configurations that rely on specimen self-constraint during cutting. Numerical analyses examine the redistribution of WRS and the development of cutting-induced plasticity (CIP) in a three-pass austenitic slot weld (NeT TG4) during the cutting procedure for each configuration. Stress intensity factor (SIF) analyses are first used as a screening tool; these analyses characterise lower stress intensities near the cutting surface when double-embedded cutting configurations are used, relative to SIF profiles from a single-cut process. The lower stress intensities indicate the development of CIP – which will ultimately affect back-calculated WRS – is less likely to occur when using an embedded configuration. The improvements observed for embedded cutting approaches are confirmed using three-dimensional finite element (FE) cutting simulations. The simulations reveal significant localised plasticity that forms in the material ligaments located between the pilot holes and the outer edges of the specimen. This plasticity is caused by WRS redistribution during the cutting process. The compressive plasticity in these material ligaments is shown to reduce the overall tensile WRS near the weld region before this region is sectioned, thereby significantly reducing the amount of CIP when cutting through the weld region at a later stage of the cutting procedure. Further improvements to the embedded cutting configuration are observed when the equilibrating compressive stresses in material ligaments are removed entirely (via sectioning) prior to sectioning of the high WRS region in the vicinity of the weld. All numerical results are validated against a series of WRS measurements performed using the contour method on a set of NeT TG4 benchmark weld specimens

Heritability estimation for growth-related traits in juvenile wild common carp (Cyprinus carpio L.) in the south of Caspian Sea

Wild common carp of the Caspian Sea is one of the important fish in the north of Iran, which has been introduced to inland aquaculture. Its genetic characteristics are investigated to set up for breeding programs that are still unknown. Using wild common carp in aquaculture is limited for uncontrolled variation in performance of fish derived from undomesticated breeders. A 7×7 factorial mating design was employed to examine genetic effects of dam and sire on growth and heritability of growth-related traits based on dam half-sib and sire half-sib families. Breeders were obtained originally from the Caspian Sea. A total of 1470 offspring were raised in 49 separate fiberglass tanks with common conditions. Body weight and length were recorded at three different ages of rearing. Estimation of heritability of weights ranged from 0.23±0.05 to 0.30±0.07 for dams and ranged from 0.15±0.03 to 0.26±0.04 for sire. Similar results were obtained with length but with less variation (0.24±0.02 to 0.26±0.01 for dams and 0.20±0.02 to 0.22±0.03 for sire). The broad-sense of weight and length are 0.23±0.04 and 0.23±0.01 respectively. The dam and sire effect on growth were significant, indicating the presence of variations among the native fish of the Caspian Sea. Therefore, it is suggested to use a length for selection that is more reliable and less affected by environment than weight at any time of growth and in respect of high phenotypic correlation (0.87-0.95) observed between weight and length. In the present study we even used wild common carp and the heritability was not higher than the domesticated common carp. It means the genetic variation for quantitative traits, for common carp of the Caspian Sea are low or it may be under pressure of inbreeding which should be studied further

Evaluation of Errors Associated with Cutting-Induced Plasticity in Residual Stress Measurements Using the Contour Method

Cutting-induced plasticity can lead to elevated uncertainties in residual stress measurements made by the contour method. In this study plasticity-induced stress errors are numerically evaluated for a benchmark edge-welded beam to understand the underlying mechanism. Welding and cutting are sequentially simulated by finite element models which have been validated by previous experimental results. It is found that a cutting direction normal to the symmetry plane of the residual stress distribution can lead to a substantially asymmetrical back-calculated stress distribution, owing to cutting-induced plasticity. In general, the stresses at sample edges are most susceptible to error, particularly when the sample is restrained during cutting. Inadequate clamping (far from the plane of cut) can lead to highly concentrated plastic deformation in local regions, and consequently the back-calculated stresses have exceptionally high values and gradients at these locations. Furthermore, the overall stress distribution is skewed towards the end-of-cut side. Adequate clamping (close to the plane of cut) minimises errors in back-calculated stress which becomes insensitive to the cutting direction. For minimal constraint (i.e. solely preventing rigid body motion), the plastic deformation is relatively smoothly distributed, and an optimal cutting direction (i.e. cutting from the base material towards the weld region in a direction that falls within the residual stress symmetry plane) is identified by evaluating the magnitude of stress errors. These findings suggest that cutting process information is important for the evaluation of potential plasticity-induced errors in contour method results, and that the cutting direction and clamping strategy can be optimised with an understanding of their effects on plasticity and hence the back-calculated stresses

Association analysis of rs1049255 and rs4673 transitions in p22phox gene with coronary artery disease: A case-control study and a computational analysis

Background The p22phox gene encodes the main subunit of NADH/NADPH-oxidase. This enzyme is expressed in smooth muscle cells of arteries, and it produces the reactive oxygen species. On the other hand, oxidative stress plays a main role in the pathogenesis of coronary artery disease (CAD). Aim The aim of this study is to evaluate the association between rs4673 and rs1049255 polymorphisms of p22phox gene with CAD in an Iranian population which was followed with a computational analysis approach. Methods In a cross-sectional study, we collected blood samples of 302 Iranian Caucasian including 143 patients and 159 healthy controls. Genotype of the polymorphisms was detected through PCR-RFLP method. A computational analysis was also performed using SNAP, Polyphen-2, Chou-Fasman, RNAsnp, and miRNA SNP databases. Results Data of case control study demonstrated that CT genotype (R = 1.84, 95% CI = 1.13–3.00, p = 0.014) and T allele (OR = 1.53, 95% CI = 1.09–2.15, p = 0.013) of rs4673 polymorphism, have a significant association with enhanced risk of CAD. But rs1049255 analysis demonstrated the absence of such an association with CAD. Indeed, in silico data analysis demonstrated that rs4673 transition could impact on function of p22phox protein (SNAP score 56, expected accuracy 75%; Polyphen-2 score 0.99, sensitivity 0.09, specificity 0.99). Data derived from miRNA SNP database demonstrated that rs1049255 polymorphism increases the affinity of attachment between has-miR-3689a-3b with 3′-UTR of p22phox gene. Conclusion Our data demonstrated that rs4673 transition may be involved in susceptibility to CAD and could be applied as a potential biomarker for this disease

Eraser Rhinolith: A case report

Nasal foreign bodies are usually received in otolaryngology practice. Although more frequently seen in pediatric patients, also they can affect adults, specifically those with mental retardation or any psychiatric problems. We presented an unusual case of the nasal foreign body, an eraser rhinolith in a 17-year-old boy with mild mental retardation presented with long-lasting nasal obstruction but no chronic infection or epistaxis. Computed tomography revealed a peripherally calcified sub-mucosal round mass in the left nasal cavity. After surgery, a round shape foreign body that looked like an eraser piece was removed from the nasal cavity. Rhinolith can present just with nasal obstruction. With properly diagnosed and appropriate surgery, all rhinoliths can be removed and complication of extraction can be minimized. © 2019, Medical Sciences University of Teheran. All rights reserved

Water quality index development using fuzzy logic: A case study of the Karoon River of Iran

Determination of the status of water quality of a river or any other water source is highly indeterminate. It is necessary to have a competent model to predict the status of water quality and to show the type of water treatment that would be used to meet different demands. By exploring the behavior and limitations of conventional methods for quality evaluation, a better overall index for water quality in Iran and its application in Karoon River is proposed. Six variables are employed for the quality assessment. Numerical scales relating to the degree of quality are established for each variable to assess variations in quality and to convey findings in a comprehensive manner. The unit operates in a fuzzy logic mode including a fuzzification engine receiving a plurality of input variables on its input and being adapted to compute membership function parameters. A processor engine connected downstream of the fuzzification unit will produce fuzzy set, based on fuzzy variable namely dissolved oxygen (DO), total dissolved solids (TDS), turbidity, nitrate, fecal coliform and pH. It has a defuzzification unit which operates to translate the inference results into a discrete crisp value of water quality index. The development of the fuzzy model with one river system is explained in this paper. Water quality index in most countries is only referring to physico-chemical parameters due to great efforts needed to quantify the biological parameters. This study ensures a better method to include special parameters into water quality index due to superior capabilities of fuzzy logic in dealing with non-linear, complex and uncertain systems.Key words: Water quality index, fuzzification, monitoring, inference system

Human agt-p.Met268thr and coronary heart disease risk: A case-control study and meta-analysis

Summary Background. Polymorphisms in genes, which is involved in the renin–angiotensin system, play an important role in the pathogenesis of coronary heart disease (CHD). Polymorphism of c.803T>C in the human angiotensinogen gene results in methionine (M) to threonine (T) substitution at codon 268 (p.Met268Thr), which traditionally has been known as M235T. This polymorphism may contribute to cardiovascular diseases. Objectives. The aim of this study was to investigate the association between p.Met268Thr polymorphism in the angiotensinogen gene and coronary heart disease (CHD) through a case-control study, which is followed by a meta-analysis. Material and methods. In the case-control study, c.803T>C genotyping of 217 subjects (102 CHD cases vs 115 controls) was investigated by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. In the meta-analysis, 31 studies were included, reflecting 12,028 people with CHD and 16,362 healthy controls. Results. The data from the case-control study revealed that MT (OR, 1.875; 95%CI, 1.060–3.316; p = 0.031) and TT (OR, 3.389; 95%CI, 1.251–9.179; p = 0.016) genotypes are significantly associated with CHD. The meta-analysis revealed a significant association in the recessive model (OR, 1.156; 95%CI, 1.011–1.321; p = 0.034). Conclusions. Although the pooled OR of the meta-analysis showed that there is an increased risk of CHD conferred by p.Met268Thr of the AGT gene, this association was weak, which could be attributed to a bias in publications. © Copyright by Wydawnictwo Continuo

An Application of Monte-Carlo-Based Sensitivity Analysis on the Overlap in Discriminant Analysis

Discriminant analysis (DA) is used for the measurement of estimates of a discriminant function by minimizing their group misclassifications to predict group membership of newly sampled data. A major source of misclassification in DA is due to the overlapping of groups. The uncertainty in the input variables and model parameters needs to be properly characterized in decision making. This study combines DEA-DA with a sensitivity analysis approach to an assessment of the influence of banks’ variables on the overall variance in overlap in a DA in order to determine which variables are most significant. A Monte-Carlo-based sensitivity analysis is considered for computing the set of first-order sensitivity indices of the variables to estimate the contribution of each uncertain variable. The results show that the uncertainties in the loans granted and different deposit variables are more significant than uncertainties in other banks’ variables in decision making