Three-dimensional cohesive fracture modeling of non-planar crack growth using adaptive FE technique

AbstractIn this paper, the three-dimensional adaptive finite element modeling is presented for cohesive fracture analysis of non-planer crack growth. The technique is performed based on the Zienkiewicz–Zhu error estimator by employing the modified superconvergent patch recovery procedure for the stress recovery. The Espinosa–Zavattieri bilinear constitutive equation is used to describe the cohesive tractions and displacement jumps. The 3D cohesive fracture element is employed to simulate the crack growth in a non-planar curved pattern. The crack growth criterion is proposed in terms of the principal stress and its direction. Finally, several numerical examples are analyzed to demonstrate the validity and capability of proposed computational algorithm. The predicted crack growth simulation and corresponding load-displacement curves are compared with the experimental and other numerical results reported in literature

Microstructure development, mechanical and tribological properties of a semisolid A356/xSiCp composite

This paper presents the results of experimental investigation on microstructure (size and morphology of eutectic Si), impact toughness and sliding wear properties of A356 Al-Si alloy and composites containing 10, 20 and 25 wt% of SiCp reinforcement produced by semisolid stirring technique. The results revealed that an increase in SiCp content leads to a reduction in the size of eutectic Si and also changes its morphology from plate-like to equiaxed. Furthermore, addition of 10 and 20 wt% silicon carbide reinforcement decreased the impact toughness by 6 and 18%, respectively. A356/25wt%SiCp composite registered the lowest impact toughness with reduction of 33% due to debonding and agglomeration of SiCp in the matrix. The sliding wear results showed that the wear resistance of the composites was significantly higher than that of the matrix alloy due to the increase in hardness as well as reduction in the size and also morphology transformation of eutectic silicon with increase in SiCp content. However, the existence of particle-porosity clustering with increasing the SiCp content to 25 wt% played a significant role in deteriorating the wear behavior of the composite

Optimization of Tube Hydroforming Process Using Simulated Annealing Algorithm

AbstractIn this paper, forming parameters of tube hydroforming (THF) process are investigated and optimized using Simulated Annealing optimization algorithm linked with a finite element commercial code. The goal of this research is to obtain the maximum formability of two dimensional (2D) axisymmetric tubes under a failure criteria based on material's forming limit diagram (FLD). The initial approximated pressure loading path is determined by proved theoretical equations. Then the Simulated Annealing algorithm written in Matlab software is combined with a nonlinear structural finite element code ANSYS/ LS-DYNA in order to optimize internal hydraulic pressure. The results are compared by experimental observations and a good agreement was observed between them

Bi-allelic GAD1 variants cause a neonatal onset syndromic developmental and epileptic encephalopathy.

Developmental and epileptic encephalopathies are a heterogeneous group of early-onset epilepsy syndromes dramatically impairing neurodevelopment. Modern genomic technologies have revealed a number of monogenic origins and opened the door to therapeutic hopes. Here we describe a new syndromic developmental and epileptic encephalopathy caused by bi-allelic loss-of-function variants in GAD1, as presented by 11 patients from six independent consanguineous families. Seizure onset occurred in the first 2 months of life in all patients. All 10 patients, from whom early disease history was available, presented with seizure onset in the first month of life, mainly consisting of epileptic spasms or myoclonic seizures. Early EEG showed suppression-burst or pattern of burst attenuation or hypsarrhythmia if only recorded in the post-neonatal period. Eight patients had joint contractures and/or pes equinovarus. Seven patients presented a cleft palate and two also had an omphalocele, reproducing the phenotype of the knockout Gad1-/- mouse model. Four patients died before 4 years of age. GAD1 encodes the glutamate decarboxylase enzyme GAD67, a critical actor of the γ-aminobutyric acid (GABA) metabolism as it catalyses the decarboxylation of glutamic acid to form GABA. Our findings evoke a novel syndrome related to GAD67 deficiency, characterized by the unique association of developmental and epileptic encephalopathies, cleft palate, joint contractures and/or omphalocele

The association between ATM variants and risk of breast cancer: a systematic review and meta-analysis

Background: Ataxia telangiectasia-mutated (ATM) gene contributes to repair damaged DNA and to regulate cell cycle; therefore, ATM variants seem to increase breast cancer risk; however, the results are controversial. So we conducted a systematic review and meta-analysis to clarify the pooled association between various ATM variants and the risk of breast cancer. Methods: The relevant studies were searched through Scopus, Web of Science, PubMed and Cochrane. Stratified and subgroup analyses were performed to explore heterogeneity between studies and assess effects of study quality. The pooled estimates logarithm with standard error logarithm of odds ratio and relative risk with confidence interval were calculated. Results: This study revealed that there is association between ATM variants and the risk of breast cancer; according to the seven adjusted case-control studies, OR of this association was estimated as 1.67 (95CI: 0.73�3.82), according to nine unadjusted case-control studies, the crude OR was 2.27 (95 CI: 1.17�4.40) and according to two cohorts, the RR was estimated as 1.68 (95 CI: 1.17�2.40). Conclusions: The ATM variants are associated with an increased risk of breast cancer that ATM V2424G mutation is detected as the most predisposing factor while ATM D1853V, L546V, and S707P variants have the least predictive ability. © 2021, The Author(s)

Complete fuzzy scheduling and fuzzy earned value management in construction projects

Complete fuzzy scheduling and fuzzy earned value management in construction projects Por: Luis Ponz-Tienda, Jose; Pellicer, Eugenio; Yepes, Victor JOURNAL OF ZHEJIANG UNIVERSITY-SCIENCE A Volumen: 13 Número: 1 Páginas: 56-68 Fecha de publicación: JAN 2012 Search For Full Text Cerrar abstractCerrar abstract This paper aims to present a comprehensive proposal for project scheduling and control by applying fuzzy earned value. It goes a step further than the existing literature: in the formulation of the fuzzy earned value we consider not only its duration, but also cost and production, and alternatives in the scheduling between the earliest and latest times. The mathematical model is implemented in a prototypical construction project with all the estimated values taken as fuzzy numbers. Our findings suggest that different possible schedules and the fuzzy arithmetic provide more objective results in uncertain environments than the traditional methodology. The proposed model allows for controlling the vagueness of the environment through the adjustment of the alpha-cut, adapting it to the specific circumstances of the project. © Zhejiang University and Springer-Verlag Berlin Heidelberg 2012.The authors want to thank Ms. Doria GIL-SENABRE, Universitat Politecnica de Valencia, Spain, for the support provided.Ponz Tienda, JL.; Pellicer Armiñana, E.; Yepes Piqueras, V. (2012). Complete fuzzy scheduling and fuzzy earned value management in construction projects. Journal of Zhejiang University Science A. 13(1):56-68. https://doi.org/10.1631/jzus.A1100160S566813

Genotyping and phylogenic study of Acanthamoeba isolates from human keratitis and swimming pool water samples in Iran

Objective: Acanthamoeba keratitis cause severe corneal infection and lead to poor vision and blindness. This disease is caused by a unicellular amphizoic protozoon called Acanthamoeba spp. that present in different environments. This study aimed to represent the existence and genotyping of Acanthamoeba spp. in patients with keratitis and swimming pool water (SPW) in Tehran Province, Central Iran. Methods: In this descriptive study, 56 clinical samples were collected from patients with keratitis and 30 water samples were collected from different swimming pools in Tehran Province. All samples were examined based on the morphological and molecular techniques. The genotypes were determined by sequencing the partial of 18S rRNA gene. Results: Of 56 clinical (corneal) and 30 environmental (SPW) samples, 30.3 and 40.0 were positive for Acanthamoeba spp., respectively. According to sequencing analysis, 94.1 of amoebic keratitis isolates were belonged to T4 genotype and only one (5.8) isolate was belonged to T11 genotype. All genotypes were detected from SPW samples were identified as T4 genotype. Conclusion: According to our results, use of contact lens and swimming in pool poses the major risk factor for amoebic keratitis in the studied area (Tehran). Moreover, T4 genotype was the predominant genotype of human keratitis and swimming pool samples there. Consequently, essential and practical measures are urgently needed to prevent subjects against this ocular seriously disease. © 202