gh.ebrahimi

Knowing the behavior of hot deformation and microstructure changes of API-5CT-L80 alloy steel is of great importance in the production of oil and gas industry pipes. For this purpose, in this research, the thermomechanical behavior of this steel was investigated by isothermal hot compression test in the temperature range of 1173 to 1373 K and strain rates of 0.001 to 1 s-1 s. The experimental results showed that the hot deformation behavior of steel is a softening behavior caused by the dynamic recrystallization phenomenon that in some conditions, the material shows complex behavior in the form of multi-peaked curves. The results of the microstructural investigation showed that with the increase in the deformation temperature, the formed grains have a larger size compared to the low temperature state, and more martensite phases are formed, which are more elongated martensite blades compared to the phases formed at low temperatures. The effect of strain rate was also significant like the effect of temperature because the rate of deformation had an inverse effect on grain growth, so recrystallized grains have enough time to grow at low strain rates. At high strain rates, the pearlite phases appeared more polygonal, and very small nucleation were observed in the austenitic boundaries of the ferrite and Wiedmannstein phase, which did not have enough time to grow, and at high strain rates, the martensite blades also tend to thin.

The main objective of this research is investigating the difference between the amount of social capital and mental health in urban neighborhoods in north and south based on sexuality studying the effect of social capital on mental health. This research is done with the use of survey methods and information is gathered through the tool of questionnaire. Statistical society of this research includes people at the age of18 years or above and live in Sari. In addition, the volume of the sample includes 450 people. The results of this research indicate that the amount of social capital in neighborhoods of Sari has a significant difference which means that the average social capital in the south neighborhoods of the city (3.85of5) is more than the north neighborhoods of the city (1.75of5). Also, the average mental health has significant difference in the north and south neighborhoods of the city. Therefore, south neighborhoods have higher mental health than the north. There is a significant difference between average social capital and mental health of women and men in the neighborhoods of Sari. The results indicate that men have higher mental health than women, while women of neighborhood have a higher average of social capital.

Excellent features including high elastic modulus and thermal expansion coefficient associated with low weight and the ability to manufacture with conventional techniques were developed Aluminium composites reinforced with cremic particles at recent decades. In this work, Al2024/SiC composites with different SiC percentages (1,2,3%) were produced by Accumulative Roll Bonding (ARB) process. In order to produce composite samples 60% reduction rolling were applied to the samples firstly and then rolled strips cutted out into two parts and again subjected to 50% reduction for 3 passes. Mechanical properties of samples were investigated. Creep tests were done at temperature and stress range about 250-350°C and 30-40 MPa respectively. According to the results, Al2024%SiC composite had higher hardness degree than the other composites because of appropriate adhesion of raw strips together due to lower volume of SiC powder in this composite and acceptable consistency of particles into the matrix. Moreover, creep life of this sample was higher than the other. It is obvious that the creep life of All composites produced were several times less than the Al2024-T3 original raw sample.

In this study، the reduction in the hot press time using high thermally conductive fillers and the influence of these fillers on physical and mechanical properties of end products was investigated. Variable factors in these treatments are type and content of fillers. Press time and other factors such as the amount of wood flour، board density، and other conditions of press were fixed. Composites were prepared from Beech (Fagus orientalis) flour، Polypropylene، MAPP، and conductive fillers such as flake and powder graphite (carbonic fillers)، and Alumina (ceramic filler). Fillers with contents of 5 and 10% in 15 and 20 minutes for press time were utilized. A thermocouple was utilized to measure the temperature in the core of composite and to determine the time being panel core as the same temperature as the hot press surface. It showed that fillers reduce press time as 2-4 minutes. Mechanical tests including tension، bending، Impact and hardness were performed. Fillers except of flake graphite had no restriction in mechanical properties. Water uptake and swelling as physical properties were also measured and fillers didn’t have a significant effect on these tests. To validate the experimental results، thermal conductivity of composites was determined and the increase in this property was evaluated. The increase in samples contain flake and powder graphite was more remarkable than those contain Alumina.

The goal of this study was present regression models for predicting resistance of joints made with screw and plywood members. Joint members were out of hardwood plywood that were 19 mm in thickness. Two types of screws including coarse and fine thread drywall screw with 3. 5، 4 and 5mm in diameter and sheet metal screw with 4 and 5mm were used. Results have shown that withdrawal resistance of screw was increased by increasing of screws، diameter and penetrating depth. Joints fabricated with coarse thread drywall screws were higher than those of fine thread drywall screws. Finally، average joint withdrawal resistance of screwed could be predicted by means of the expressions Wc = 2. 127× D1. 072 × P0. 520 for coarse thread drywall screws and Wf =1. 377× D1. 156 × P0. 581 for fine thread drywall screws by taking account the diameter and penetrating depth. The difference of the observed and predicted data showed that developed models have a good correlation with actual experimental measurements.

The goal of this study was to investigate withdrawal resistance of doweled joint with plywood members and establishing a predicting mathematical model for such joints in which regularly dowel is installed perpendicular to surface and also edge of plywood. Joint members were out of 11-ply hardwood plywood (Hornbeam، Beech and Alder) that were 19 mm in thickness. Dowels were fabricated out of Beech and Hornbeam species. Their diameters (6، 8 and 10 mm) and depths of penetration (9، 13 and 17 mm) in joint members were chosen variable in this experiment. Results have shown that withdrawal resistance of doweled joints made on face and edge of plywood members، increases with increase of dowel’s diameter and its penetration depth. Joints made with dowels of Hornbeam had higher than dowels of Beech ones. Highest withdrawal resistances (2951 N، 2441 N) were observed in joint on face and edge side of plywood members made with dowels of Hornbeam which were 10 mm in diameter and their depth of penetration was 17 mm. Lowest withdrawal resistance values (799 N، 784N) were of Beech wood dowels which were 6 mm in diameter and 9 mm penetrated into members.

This study was carried out in order to determine the effect of shoulder thickness (including 1. 5، 5، 10، 15 and 18. 5 mm)، loose tenon length (15، 20، 25، 30، and 35mm)، width of loose tenon (20، 25، 30، 35، and 40mm)، and loose tenon wood species (Beech، walnut، oak، sycamore، poplar، and fir) on bending moment capacity of mortise and loose tenon joint. Polyvinyl acetate (PVAc) adhesive was utilized in constructing joint specimens. Totally 100 T-type joints were made and tested in the same way. The results showed that the difference between the groups was highly significant in terms of shoulder thickness، loose tenon length، and width of loose tenon. Shoulder thickness directly affected bending moment capacity of joint. The highest bending moment capacity was obtained in joints with 1. 5mm shoulder thickness. As loose tenon length and width were increased، the strength of the joint was correspondingly improved. Test joints with loose tenon made of beech wood gave higher bending moment capacity than joints with loose tenon constructed with other wood species.

The seven-adventures of Rostam، in particular، and other Iranian seven-adventures such as Esfandyar seven-adventures or Gorshasp pseudo-seven-adventures are a kind of eternity search، a kind of battle with selfhood that aims to facilitate the problems، the difficulties of evolution way and human ascent. By discussing and analyzing Iranian seven-adventures، this research aims to study the fourth adventure of all the seven-adventures، which is، at the surface، the battle between man (hero، champion) and woman but، in essence، it is the battle between fire and water. Fire is the son of Ahura Mazda and water is its enemy. Water، which was at one time the symbol of holiness and purity of Ahura، became a satanic element during Sassanid era and following the dominance of Zorvani thoughts on religious system of that time. By analyzing Rostam، Esfandyar، Gorshasp، Heracles fourth adventure and looking at Zal and Roodabe stories، Khajavi Kermani’s Sam-Nameh، Nezemi’s Khosro and Shirin and Mahmoud Dolatabadi’s Kalidar، we try to prove this hypothesis.