سید رسول سجادی

Alloying elements and temperature are non-uniformly distributed in the wall of a steel pipe during the manufacturing process. In this study, the effects of these non-uniform distributions on mechanical properties were evaluated macroscopically. Plate-type tensile specimens were cut from the wall of a steel pipe in a way that each specimen was separated from a specified location along the wall thickness. The results of tensile tests showed significant variation of mechanical properties in the thickness direction. To investigate the effect of this variation on the steel deformation, a thick tensile specimen with a thickness equal to the pipe wall thickness was then modeled as a multilayer structure based on the measured mechanical properties. First of all, with the help of finite element simulation and according to the obtained stress-strain curve from the tension test, GTN damage parameters have been calibrated for every single layer, and then, these parameters were used in modeling the multilayer specimen. According to the results, the numerical load-displacement curve obtained from multilayer modeling did not exactly match the experimental curve of the thick specimen; this can be due to different governing stress states in thin and thick specimens and also the effect of residual stresses.

Poor and low fertility in IVF cycles can be due to hormonal status and hormonal levels results from induced ovulation protocols. In cases of decreased ovarian reserve، follicular response to gonadotropin stimulation also decreases and the small number of oocytes will be resulted. This article measured the predictive effects of anti-mullerian hormone (AMH) and follicle-stimulating hormone (FSH) levels and antral follicle count (AFC) in infertile women prior to IVF and ICSI on ovarian response and the success rate of pregnancy.

This prospective observational study was conducted during 2011 to 2013 on 60 patients referred to Montaserie infertility center of Mashhad، Iran for IVF or ICSI. Serum levels of AMH، FSH، CBC، LFT، TFT، Ur، Cr and Prolactin were measured and vaginal ultrasound was performed to determine AFC. Required number of gonadotropin ampoules were determined and recorded. At days 20 and 21 of menstrual cycle patients underwent imitated transfer and GnRH was injected. At the 2nd day of menstruation، gonadotropin was injected. 6 days after injection، the ultrasound was performed every other day until at least two follicles up to 17-18mm were observed. Based on the number of follicles، 5000 to 10000 units of hCG was administered. After 36 to 40 hours، IVF or ICSI was performed. Finally bHCG was measured as an index of pregnancy. Data were analyzed by SPSS software version 11andt-test and chi-square tests. P value less than 0. 05 was considered significant.

The mean number of antral follicular and oocytes before and after treatment was 4. 43±4. 17 and 3. 09±3. 71، respectively. Mean of bHCG after treatment was 94. 79±265±86 Pmol/dl. Adequate ovarian response occurred in 52 cases (86. 7%) and the incidence of pregnancy was 30% (18 cases). In all patients، AMH was 1. 34±2. 66 Pmol/dl and FSH was 6. 81±4. 54 Pmol/dl. Comparison of hormone levels in women with positive and negative ovarian response showed no significant differences (p>0. 05)، but the differences of these hormones were significant in terms of pregnancy and pregnancy outcomes (p<0. 05). In pre-treatment، the level of AFC in these groups showed no significant difference (p>0. 05)، .

AMH and FSH hormones are predictive factor for positive pregnancy in infertile women after IVF and ICSI.

In this paper, wheel-rail contact problem in presence of rail surface crack is investigated. The reason for investigating this problem is significant effect of wheel-rail contact on stress intensity factors and also the effect of crack on contact pressure. ..

In this paper, wheel-rail contact problem in the presence of rail surface crack is investigated. The reason for investigating this problem is significant effect of wheel-rail contact on stress intensity factors. In this research, by using finite element method and a commercial software, wheel-rail is modeled under partial slip rolling condition. Contact elements are used to model the interactions between the wheel-rail contact surfaces and the crack surfaces. Stress intensity factors are calculated through a numerical displacement extrapolation method. The effects of crack orientation, crack length, friction coefficient and contact on the stress intensity factors are studied. The results indicate that KII has greater values than KI. Therefore, shear mode may dominate the tip behavior in this wheel-rail contact problem. As the wheel passes over, the complicated crack edge deformation changes the direction of interfacial shear stress and this causes variation in KII. Fluctuation in KII is the main factor of fatigue crack propagation in the wheel-rail contact problem.