m. aghaei

This paper presents the optimization of a system of square cascades for separating the middle components of xenon. It also presents the optimal use of square cascades in this system. As an example, the separation of 130Xe, an element whose middle isotope is much more complex than any of the other isotopes of xenon, is provided. The Grey Wolf Algorithm is applied for optimization. and the parameters of cascade feed flow rate, cut off the cascade, feed location, feed flow of gas centrifuges (GC), and the cut of the first stage are optimized in such a way that the maximum recovery of the target isotope and the maximum cascade capacity are achieved. Based on the optimization results, the more steps the cascade has, the fewer separation steps are needed for the nine selected cascades with 180 GCs. As a result, both the recovery factor and the amount of product increase.

In designing the fuel rod, having a reliable prediction of fuel performance is of high importance in order to comply with safety principles. Various computer codes have been provided for this purpose. Each of these codes uses different mechanical models, numerical and analytical methods. Accordingly, the purpose of the present work is to develop Fortran computer software for mechanical and thermal analysis of fuel rods using numerical methods, especially applying the principle of virtual work in mechanical analysis of fuel rods in steady-state conditions. The finite element method is used to solve the equations. The mechanical analysis includes phenomena such as swelling and fuel density and clad creep. Through these phenomena and simultaneous performance of mechanical and thermal analysis, fuel-clad interaction, stress and strain rate in fuel and clad, fuel center temperature, oxide layer thickness, fuel, and clad temperature distribution during operation is obtained by the code. The results of the code are compared with the results of the analytical method which are available in other research works. Finally, for the VVER1000 reactor, mechanical and thermal analysis of the fuel rod was performed over a 1600-day interval. According to the simulation, the fuel-clad interaction occurs after 1250 days.

The effects of atmospheric pressure of the site of installation of a centrifugal two-stage heavy medium separator is of crucial importance because the pressure difference between the medium input and the sink output streams is adjusted by the back pressure rings. However, contrary to the dense medium cyclone, the raw feed ore into this separator is sluiced without pumping.  In this research, the effect of atmospheric pressure on the flow pattern inside the Tri-Flo separator is investigated using the computaional fluid dynamic (CFD) simulation. Therefore, the volume of fluid (VOF) model and discrete phase model (DPM) were used for the calculation of the diameter of the air core and the behavior of solid particles, respectively. Reynols stress model (RSM) was used for turbulence modeling. Simulations were performed in three different atmospheric pressure including 1, 0.86 and 0.64 atm, representing the site of installation at sea level and heights of 1250 meters and 3500 meters above the sea level, respectively. The CFD simulation results showed that the change in atmospheric pressure has some effects on the flow fields, macroscopic parameters and the performance of the Tri-Flo separator. The results of simulation were validated against the experimental data achived using the transparent laboratort Tri-Flo separator. The fluid velocity in output streams and the size and the pattern of air core were used for validation. The decrease in Ecart propale error (Ep) of the separator and increase in the medium recovery were observed, when the atmospheric pressure was decreased. However, the effects were in the margin of 2%. According to the results of this research, the Tri-Flo separator can be used in different elevations from the sea level, without serious problem in the operation regime.

Currently, composite structures have many applications in various industries including aerospace, automotive, marine, and petrochemicals. In most of these applications, the structure is under dynamic and static loads and it can cause buckling, vibration, and fatigue. Therefore, the static and dynamic analysis of these structures is essential in order to understand their characteristics, including buckling, natural frequency, and the shape of vibrating modes. One of the most important non-destructive methods for predicting the buckling load of the structure is the vibrational correlation technique (VCT), which is based on frequency variations with the axial load. In this study, an experimental study of the buckling load of composite sandwich plates with lozenge core has been investigated. The hand lay-up method has been used for fabrication of the composite sandwich plates. One of the specimens was used for the modal test. In order to verify the results of the VCT, the buckling load of four specimens was calculated by the experimental buckling test. The error of VCT was 2.1 %. Hence, the efficiency of the VCT for composite sandwich plates with lattice core was confirmed. Also, by investigating the effect of applied load percentage on the accuracy of the VCT, it was found that for the applied load of more than 63% of the buckling load, the accuracy of prediction of the vibrational correlation technique is acceptable.

Two-stage centrifugal separators are the last generation of gravity separators for the separation and upgrading of minerals. Gravity upgrading techniques are methods by which a mixture of particles with different dimensions, shapes, and masses can be separated by gravity, centrifugal force, and other forces by the flow of fluid, especially water (or air). The fluid flow inside such separators is always turbulent. The selection of a suitable turbulence model is an important stage for the prediction of the fluid flow pattern in numerical simulation. The purpose of this research was to find the suitable turbulence model for the prediction of hydrodynamic parameters in a two-stage centrifugal separator using computational fluid dynamics (CFD) modeling. For this purpose, multiphase simulation of the separator has been performed using five turbulence model including k-e, renormalization group (RNG k-e) and Reynolds stress model (RSM). Air core pattern, velocity distribution and partition curve of discrete phase were used for evaluation of the effect of turbulence model on the flow field. The results of the CFD simulation were validated using experimental data. The difference between the results of RSM simulation with the experimental results for fluid recovery, air-core size in the first and second stage of separator were 4.73%, 4.3% and 5.2%, respectively. The results of turbulence models of k-e and RNG k-e were not in accordance with the experimental results.

Because of human exposure to various environmental risk factors during the lifetime, the actual exposure estimation has been considered as one of the most important challenges for researchers and decision makers. Considering the contribution of environmental risk factors in the burden of diseases, this study aimed to provide new approaches in exposure assessment filed based on the latest studies carried out in the world. In this review article, according to the objectives of the study, literature related to new approaches in exposure assessment was identified through electronic searching in Scopus, PubMed and web of Science databases. After introducing new approaches, the most important sources of errors and limitations were also examined to reduce uncertainties of exposure estimation in these studies. The results of the study showed that comprehensive exposure assessment using new approaches in personalized exposure assessment, targeted and non-targeted analytical methods, -omics technologies, novel exposure matrices and computational models presented in this study can help researchers to identify the effective factors in development and increase assessor’s knowledge of mechanisms, exposure pathways and biological responses. The use of new exposure assessment approaches provides new opportunity for researchers to better understand the biological processes in the development of diseases and estimate the actual human exposure to environmental risk factors.

Nursing education as part of the higher education system exapands  rapidly in the world in recent decades.Neglecting of the quality of educational contents and efficacy of graduated is an important cocerned. Due attention to few studies have been done on comparing the educational structure of the MSc nursing school of pediatric in Iran with other countries, this study aimed to compare the MSc nursing curriculum for pediatric in Iran and Toronto. This descriptive - comparative study was carried out in 2018. In order to comparing  the elements of the Iranian and Canadian MSc nursing curriculum for pediatric, necessary data  wsa collected through Internet search and the four-step model of George Beredy was used to  compare curriculum. Results show that curriculum in both faculties is full-time, in-person, and emphasis on student-centered principal. At the nursing faculty of Toronto, more emphasis is placed on students creativity and students participation in education,  also, evidence-based education and  research are among the core elements of their curriculum. Regarding the structure of the course and acceptance conditions, there are many differences, but in general there are similarities in goals, roles and abilities. The leadership role of graduated students and professional cross-border education are Toronto curriculum profile. The MSc curriculum of Pediatric nursing in Iran compared to the University of Toronto needs to be modified in light of the growing needs of this field and the expectations of graduates. Therefore, it is recommended to strengthening educational program, the curriculum of Pediatric nursing in Iran follows the world-wide educational standards according to its educational bases.

: Exercise training with blood flow restriction (BFR)is a modern method of training that has been developed in two recent decades and has been used for improvement of performance. Therefore, this study was conducted to identify the effect of 4 weeks rock climbing with blood flow restriction on athletic performance and some muscle damage indictors  in elite rock climbers. : In a semi experimental research method, 12 male and 12 female elite rock climbers with at least 4 years rock climbing experience and age range of 23 to 27 years and a fat percentage of 10 to 20 percent purposefully selected among the climbers, and allocated in two equal BFR and none-BFR groups. Both groups performed 4-week rock climbing training program consisting three sessions per week and each session was 90 minutes, severity of each session was 60 to 80% of climbing grades. Blood samples were obtained in baseline and after four weeks of climbing training to determine the amount of lactate dehydrogenase (LDH), creatine kinase (CK) and lactate. Also, hand grip, explosive anaerobic power, body fat percent, adduction strength in upper body and degree of climbing was measured. For data analysis, independent T test was used at α ≤ 0.05. After 4 weeks of climbing with and without limitation of blood flow, the index of muscular damage of LDH, CK did not show significant difference in response to climbing exercise. But lactate level was lower in BFR rather than NBFR. There are not any difference in Hand Crip strength, explosive anaerobic power, body fat percent, adduction strength in upper body between BFR and NBFR groups. But in degree of climbing, the result showed the better performance in BFR than NBFR (P <0.05). According to the results of this study, rock climbing training with or without BFR, do not increase muscular damage. and it could influence on performance.

The defensive power of a society cant be Summarized in its military power. The combination of The idea of "defense" and its peculiarities are among the compositional and fluid concepts throughout the
history of human thought so that it has different and opposite dimensions from culture to culture and from school to school. The idea of "defense" in Shia political culture has a different meaning compared to other schools of thought. Therefore, a proper recognition of this idea requires an independent research on its scope and boundaries. Imam Khamenei, as the most influential religious scientist in the Shia world in the present age and as the heir to the pure thoughts of the Imams, has important and influential point of view on this topic. therefore, the examination of the boundaries of defense in his thought is of major importance for proper understanding of Shia political culture. From this perspective, the main question of the present study is as follows. What are the peculiarities of the idea of defense in Imam Khamenei thought? To answer this question, the author examines the concept of defense in four areas of ontology, epistemology, teleology, and methodology in the thought of Imam Khamenei. The findings of the research showed that in the thought of Imam Khamenei, the idea of defense is understandable through two-dimensional ontology, empowering and capability -centered epistemology, bliss-seeking teleology, and moral methodology. The present paper is a qualitative study using descriptive-analytical method. Its information is obtained through documentary study.

Osteoporosis is a multifactorial disease that leads to etiology leading to morbidity and economical disturbances. This study designed to evaluate the prevalence of osteoporosis in patients referred to Gorgan’s densitometry centers with respect to age, gender and BMI.

In this descriptive-analytic study, from 3000 subjects referred to the densitometry centers of Gorgan, 300 subjects were selected via a random sampling method. Individual characteristics and densitometry results were collected from densitometry records. Data were analyzed by SPSS and chi square test and linear regression.

The overall prevalence rate of osteoporosis was 33.7% and 16.7% according to lumbar and femoral region, respectively. Lumbar and femoral BMD mean were 0.92±0.19 and 0.77±0.167, respectively. Association between age and osteoporosis in lumbar region (P-value