mehdi farahani

Simulation of Nitinol shape memory alloy stents behavior for application in trachea stent implantation has been strategically used for solving trachea stenosis. Predicaments like insufficient radial strength, low twisting ability, inappropriate dynamic behavior and restenosis are expected to be solved by the introduction of new designs. Superelastic shape memory alloy stent is an interesting alternative for minimizing these tight spots. The application of finite element method to predict metallurgical of superelastic shape memory alloy stents for trachea duct dilatation is supported by conventional crimp tests. The present simulation modeled the stent material’s superelasticity based on Auricchio theories (Helmholtz free energy) and Lagoudas (Gibbs free energy).Nitinol shape memory alloy stents with material properties contain Af temperature of 24°C° is shown to have the best mechanical performance for clinical applications. Owing to lower chronic outward force (COF), higher radial resistive force (RRF), and more suitable superelastic behavior. Model calculations showed that a very high change of Af temperature could exert a substantial effect on practical performance of the stent. This FEM model can provide a convenient way for evaluation of biomechanical properties of peripheral stents given to effects of metallurgical properties such as austenite finish temperature.

In the present study, the finite element method was used to study the effects of geometric parameters on superconductive behavior of new geometries Z- Shape of shape memory alloy stent for application in the trachea using a radial loading(crimping) test. The material model used to describe the properties of a shape memory material based on the Helmholtz free thermodynamic energy (Aurichio model). In this numerical study by creating a new design of the stent and by choosing different mechanical properties and changing its geometric parameters, the mechanical performance of the stents was evaluated using finite element analysis with empirical verification. The modified geometric parameters are the thickness, number of vertices and angles between the stents. Reducing the thickness of the stents from 0.3 to 0.2 in the same of angle between the length and the number of bends of the stent causes reducing the stiffness = 37.87%, reducing the radial mechanical strength to open ducts (COF) = 50%, reducing the radial force = 38.35% and increasing displacement = 0.2%. The stents with lower thickness have a better mechanical performance due to more complete mechanical hysteresis loop, less radial mechanical strength to open ducts(COF), more radial resistive mechanical strength related to ducts(RRF), less radial force, less stiffness, more displacement, less stress ,high strain at stent critical points, and high martensite formation at less strain.

The aim of this study was to investigate the effect of oil prices and fluctuations on the return on assets of companies listed in the chemical and refining industry of the Tehran Stock Exchange to collect data related to research in companies listed on the stock exchange. The method of the present study was applied in terms of purpose and regression analysis in terms of method. The statistical population of this study includes companies listed on the Tehran Stock Exchange and systematic screening or elimination method was used to select the sample. In this way, first, all the companies that could participate in the sampling were selected and then, among them, the companies that were not eligible were eliminated, and finally, the companies that remained were selected for the test. The research period was considered between 2012 and 2018. In this study, the data required to test the research hypotheses were extracted from the annual financial statements of companies (Codal site) and the website of the Stock Exchange Organization. In this way, first using quantitative methods including tools in descriptive statistics, such as mean, standard deviation of the data used was analyzed and to test the hypotheses of this study and determine the relationship between independent and dependent variables, econometric models and hypotheses were used. The corresponding panel multivariate regression method was examined. The results of examining the hypotheses showed that oil price fluctuations affect the return on assets of chemical companies that are members of the Tehran Stock Exchange. Oil sanctions affect the relationship between oil price fluctuations and the return on assets of chemical companies that are members of the Tehran Stock Exchange.

Goal: Imposing the discretionary interest rate renders the interest rate market susceptible to variety of shocks. Monetary officials should be well aware of the durability and temporal impacts of these shocks on the macroeconomic variables. Using 120 macroeconomic variables of Iran economy within the period of 1984-2013 , this study investigated whether there is a statistically significant relationship between the shadow reference interest rate (as a representative of the interest rate market) and prescribed interest rate? If so, what would be the consequence of the gap (difference) between these two rates in terms of the response of macroeconomic outlets?
This paper estimates the "economy-wide" response to shocks to the interest rate using an iterative maximum likelihood estimation method.Applying Factor-Augmented Vector Autoregressive (FAVAR) method, it was investigated how macroeconomic variables respond to interest rate oscillations (shocks). To do so, first, key macroeconomic variables for Iran economy are identified (i.e., the variables that robustly represent Iran’s macroeconomic variables). As for the modeling, measurement and transfer equations have been assessed.Technically, the 120 time series constitute the measured part in a state space system. The state transition part of this system contains the dynamics of the driving forces and is represented as a vector autoregression of the shadow reference interest rate augmented by a few dynamic factors extracted from the large cross-section of time series. This state space system is denoted a factor-augmented VAR (FAVAR) by Bernanke et al. (2005). I estimate the FAVAR by the fully parametric one-step EM algorithm as an alternative to the two-step principal component method and the one-step Bayesian method in Bernanke et al. (2005). The EM algorithm which is an iterative maximum likelihood method estimates all the parameters and the dynamic factors simultaneously and allows for classical inference. I demonstrate empirically that the same impulse responses but better fit emerge robustly from a low order FAVAR with nine correlated factors compared to a high order FAVAR with fewer correlated factors, for instance six factors. This empirical result accords with one of the theoretical results from Bai & Ng (2007) in which it is shown that the information in complicated factor dynamics may be substituted by panel information.
According to Bai and Ng criteria, Expectation maximization, and the model, it is argued that GDP, monetary base, oil revenues, inflation, interest rate, and exchange rate are the key macroeconomic variables. Regarding the first question, it was shown that as the difference between the shadow reference interest rate and interest rate approaches zero, economic growth increases. This result has important policy implications: Policy makers are advised to set the prescribed interest rate close to the shadow reference interest rate. As for the second question, it was examined how the four main Iran economy outlets respond to the shocks in terms of durability and the temporal impact. The results indicate that as far as the temporal impact is concerned, capital market and exchange range exhibited the minimum (0.1 percent deviation from the mean) and maximum values (0.4 percent deviation from the mean), respectively. As for the durability, housing and banking outlets show approximately similar responses. It is worth noting that the standard deviations of shocks in interest rates caused delayed responses in GDP, unemployment, consumption, and bank deposits (one year delay). This demonstrated the rigidity of these variables. Inflation and capital market variables, however, do not show any rigidity. The same result has been reported as slow and fast moving variables in Bovin and Eliasz, (2005).
The Central Bank should adopt necessary measures in response to the oscillations pertinent to the prescribed interest rate. Moreover, monetary officials should be well aware of the durability and temporal impacts of such oscillations on macroeconomic variables. Based on their thorough understanding of the impacts, the officials can introduce effective measures. In this study shadow reference interest rate significantly explains the macroeconomic variables. Policymakers are advised to set the prescribed interest rate close to shadow reference rate.

In this study, to enhance the capacity of Islamic banking in the country with an emphasis on religious learnings and using nearly half a century of banking experience and financial institutions in the world to examine the experience of Islamic banks in five selected Islamic countries including Iran, Malaysia, Pakistan, Jordan and Bahrain, the question of whether the mobilization, allocation and collection of receivables frameworks are different in these countries is arose out and discussed. In this regard, the business models of banking systems in the selected countries as well as the way of funding, resource allocation and bad loan collection are discussed.
The obtained results show that among the differences between interest-free Islamic banking law enacted in 1983 in Iran with that of other countries, the existence of dual banking system (Islamic banking law along with usual banking rules), resource funding on the basis of Mudaraba Contract, the use of restricted and unrestricted investment deposits, the establishment of an independent legal council to allocate some of delay penalties to the charities, and asymmetry in damage can also be addressed.

The purpose of this study, is evaluating the effectiveness of monetary policy on the economy. Accordingly, in this study using the Factor Augmented Vector Auto Regressive model and maximization expectations algorithm and 120 economic variables with 1368 to 1392 has been studied to assess the effectiveness of monetary policy in Iran. Considering that interest rates in the banking operations cannot be regarded control tool for the monetary authorities, in this study, using an alternative interest rate. The results indicate that, interest rate shocks have a delayed effect on the money market. So that, in this case one standard deviation hit to interest rates shock, money market has reactions after three months delays to show shock which mainly due to stickiness of contracts related to investment deposits respectively. This Issue, In the labor market and product market reaction is similar.On the other hand, according to the factor agmented vector autoregressive model based on the estimated model with different factor and lags operator, to be appear, according to Bernanke et al (2005) is a trade - off between the number of factors and lags in Iran's economy, so that by increasing the number of operating of factors reduced lags.

The influential factors of organizational training in a holding company affiliated to the ministry of energy examined by a diagnostic trichotomy model. Using a descriptive research inquiry a content analysis of organizational characteristics was applied. The sample was included all managers and experts that worked at the training and development department of all 90 affiliated companies which are under the holding company's directions. The means of gathering data was a series of structured, semi-structured, and unstructured/open questions and interviews. In order to content analysis, after extracting relevant concepts, themes, and contents, each items classified into one of the three (structural, behavioral, environmental/context) dimensions of the model. The results show that structural component has a more influential effect on explanation of strength and weakness of training and development activities than the other two components. In this regard, the article concluded that structural/process aspect of organizational training met with more difficulties than behavioral and context so need to pay more attention. Finally, it seems that the trichotomy model of analysis is a useful diagnostic approach to the organizational pathology and could lead to appropriate applied results.

Priority setting is one of the most important issues in health research systems. No national health system can afford to finance all research projects proposed by researchers, especially in developing countries. Therefore, we decided to set the main national health research priorities in Iran using the Essential National Health Research (ENHR) method. All of the Iranian universities of medical sciences and other stakeholders collaborated in this study. The methodology for research priority setting was based on needs assessment and ENHR. The total number of research priorities gathered from universities of medical sciences was 6723. The proportions of topics related to basic science, applied and development subjects were 17%, 78% and 5%, respectively. Further analysis of the data showed that almost half (46.3%) of the research priorities were descriptive, 36.0% analytical, and 17.6% interventional. The research priorities were divided into 9 main areas, namely, communicable diseases, noncommunicable diseases, health system research, pharmaceutical sciences and industrial pharmacy, basic science, traditional and herbal medicine, nutrition, environmental health, and dentistry. Up to now the common procedure for research priority setting has been, with a top-to-bottom approach, managed by a limited number of researchers and experts, while in the method presented in this paper a bottom-to-top approach is used, which is more effective.

In this study, The effect of financial development on economic growth in both developed and developing countries will And will be discussed Whether the financial development indicators have a positive effect on economic growth And it works in both developed and developing countries are different or not? Statistical studies have been conducted on three groups in 120 countries Statistical studies have been conducted on three groups in 120 countries. Calculations for total has offered initially and then 120 countries have been divided into two categories. 53 high-income countries (including America, Germany, France, etc.) and the average high and average low of 67 low-income countries (including Pakistan, India, Iran, etc) for the years 2008-1975 as is taken. Indicators of stock market development as well as indicators of financial development, we took advantage. Contracts to Panel and GMM techniques are used. Model results suggest that Positive relationship between financial sector development and economic growth Two groups of high-income countries and low-income and low-middle and middle to high, there is And the effect of high and middle-income countries is stronger.