s. akbarzadeh

Finding a way to reduce the wear resulted from aperities interactions in mixed lubrication regime is an interesting area. One of the inspiring solution is surface texturing. Using a convenient laser, a textured surface with arbitrary micro cavity shape and size was prepared accurately. In this study, the effect of laser surface texture on the wear and friction behavior of discs in line and point contact in mixed lubrication regime was investigated. The effect of texturing area, linear velocity, and vertical load were examined. The friction coefficient variation reaches a narrow margin after an adequate distance. The results showed that wear decreases with increasing speed and decreasing the applied force. Comparing the results between plane and textured discs, it was found that the coefficient of friction was reduced between 12 and 19% and theamount of wear was reduced by almost more than 40%.

Nowadays analysis of mechanical seals is of great importance since it causes improvement in the performance of mechanical systems and it enables one to reduce the leakage in the seal. In this paper a MTM 30 mechanical seal has been analyzed. The analysis has been conducted in both thermal and isothermal modes using finite difference method. The pressure distribution as well as film thickness has been predicted and compared to the published results available in the literature. The results show that considering thermal effects results in an increase in pressure for 16.55% and a reduction in film thickness of 33.4% compared to the situations in which isothermal analysis is conducted. A parametric study has been conducted which evaluates the effect of speed, viscosity, and load on the performance of the mechanical seal. Film thickness, pressure distribution, and film thickness has been studied in this parametric study. The results in this method have been shown to be in good comparison with other results.

In March 2019, a number of synnematous fungal specimens were isolated from the dead tissues of Pistachio vera (pistachio) seedlings in a greenhouse at the Azarbaijan Shahid Madani University of Tabriz, Iran. Preliminary identification based on morphological characteristics showed that the fungal isolates belong to the genus Cephalotrichum. Two species namely C. asperulum and C. gorgonifer were identified by combining morphology and phylogeny inferred from ITS-rDNA sequence. To our knowledge, C. gorgonifer is a new record for the Iranian Funga. Moreoverpistachio is matrix nova for C. aspeerulum and C. gorgonifer.

The need for a high-temperature operation to increase efficiency has led to the use of protective coatings called Thermal Barrier Coatings (TBCs) to protect turbine equipment against destructive conditions and relatively high thermal loads. However, the coatings themselves are also gradually affected by these destructive conditions. In the present study, based on the microstructural characteristics of thermal barrier coatings, first, the modeling of the deposition process and the fabrication of these coatings was done using the finite element method. In this modeling, the deposition process of TBCs for studying the thermal and mechanical behavior of these coatings simulated. Then the temperature field and the residual stresses obtained during and after the deposition process and cooling to ambient temperature has been studied. Subsequently, by applying thermal loading and simulating the actual working conditions of the turbine, the thermal and mechanical behavior of TBCs was evaluated in working conditions and the distribution of the temperature and stress field in the system was calculated. The results show that the maximum residual stress after cooling is at the interface between the substrate and the bond coat. The obtained results and the accuracy of the proposed model validated by experimental reports.

Nowadays, many attempts have been made to replace conventional materials with polymers which have the advantage of having less weight and higher formability. Polymers besides these advantages have some shortcomings. One method to overcome these shortcomings is to strengthen them by adding other materials to polymers. As an example, polymer nanocomposites are made by adding nanoparticles to polymers to enhance their tribological performance. In this paper, an experimental and numerical study on the correlation between temperature rise and the wear rate in the polyethylene (PE) with 10% ZnO nanoparticles has been investigated. A comparison between pure PE and polymer nanocomposite has been made. A 3D finite element model has been developed in Abaqus to study the wear in the contact of pin and the disk. The results predicted by the FE model are compared to the experimental data obtained in this research using the pin on disk test rig. According to the results, a non-linear relation between temperature changes and wear rate has been developed.

One of the most important challenges industry has always been facing is the wear phenomenon. Wear is the cause of huge deteriorations in parts and results in a drop in performance and lifetime of different machines. Therefore, finding solutions to reduce friction coefficient and wear is of special importance. The present research aims at numerical and experimental investigation of friction coefficient and wear in the presence of nano-lubricants. In the numerical section, to tackle different scales of contact components, two sub-models are developed. In the first one, contact of asperities is modeled and the properties of contact surfaces are taken into account. Second sub-model simulates nano-particles in the contact region. Furthermore, a series of experiments are conducted under different loads, speeds, and different values for Zinc Oxide nano-particle weight percent using a pin-on-disk test rig. Results show that predicted friction coefficient and wear volume in theory are reasonably in agreement with experimental results. It was found that adding nanoparticle to the lubricant can be beneficial in terms of friction reduction.

Introduction &

Ocular trauma is one of the important reasons of visual loss which can cause multiple damages to eyelid، eyeball and adenexal tissues. Furthermore، ocular trauma is one of the major causes of unilateral blindness and the third leading cause of hospi-talization in ophthalmology wards. The aim of this study is to determine the prevalence and characteristics of eye trauma at Farshchian hospital in Hamadan in 2012.

In this cross-sectional descriptive study، 70 patients with ocular trauma، admitted to Farshchian hospital، were studied. We assessed the age، sex، job، educational level، location، cause of trauma، its type and site of injury. The data was analyzed by SPSS 16 software and t،? 2 statistical tests.

The mean age of patients in this study was 24. 01 years (SD= 16. 04). Among 70 pa-tients، 58 people (82. 1%) were males and 12 patients (17. 1%) were females. The most com-mon cause of trauma was observed in 19 patients (27. 1%). The most common location of the trauma in this study was homing، seen in 28 patients (40%). Among the 70 patients، 29 peo-ple (41. 4%) had open globe injuries، 25 people had (35. 7%) closed globe injuries، 5 patients (7. 1%) had burning and 11 patients (15. 7%) had adenexal injury.

The results showed that most ocular traumas occur in the early ages and in males. The most common type of them is open globe injury and the most common cause is a sharp.