فهرست مطالب محمد خسروآبادی

Performance of cutting fluids in machining of different materials is critical importance in order to improve the efficiency of any machining process. The objective of this research is investigation the effects of cryogenic cooling on tool wear and power consumption in the turning process of AISI 304 austenitic stainless steel. Cutting speed and cutting time each at three levels were selected as cutting variables. Response surface methodology (RSM), employing a face-centered central composite design scheme, has been used to plan and analyze the experiments. The relationships between machining parameters and output variables were modeled using RSM. Analysis of variance (ANOVA) was performed to check the adequacy of the mathematical model and its respective variables. The results showed a good agreement between the measured tool wear and power consumption and predicted values obtained by developed models. Suitable mathematical models for the response outputs were obtained using the ANOVA technique, in which significant terms were chosen according to their p values less than 0.05 (95% of confidence interval). When experiments and analysis of results were done, it is observed that tool wear was decreased till 67.5% and power consumption was decreased till 24% in cryogenic cooling method when compared with dry machining.

Steel plate shear walls have been used as lateral resistant systems at several buildings particularly at high rise building during past three decades. This system contains appropriate rigidity to control displacements and also have ductile failure and high energy dissipation mechanism, so it can be used for new buildings or strengthening existing structures at seismic prone areas. Generally steel plate shear walls are consisting of steel plate walls and two boundary columns and horizontal floor beams. In this paper, initially a steel plate shear wall of a 5-floor building at high seismic area was designed according to AISC 341-05, then ABAQUS finite element program was used to investigate the seismic behavior of structure and get hysteresis curves under cyclic loading and also investigate the several parameter effects on local instability and non-linearity of material at designed typical shear wall and also the other new walls with different opens and rigidities. Numerical analysis results indicate that rigidity, shear capacity, and energy dissipation of wall were increased whenever column dimensions and length to height ratio was increased. Moreover, the main failure mode as global buckling was happened at the base of the column with increasing of the number of floors, so indicating the decreasing capacity and rigidity. And also the results showed that more open dimensions caused the higher ductility, decreasing capacity and rigidity and dissipation. The higher capacity, rigidity, energy dissipation, and ductility were observed at shear wall consisting of the more stiff nesses.

With regard to the increasing income inequality, higher unemployment rates, urbanization, economic inefficiency, lack of economic justice in different societies especially within developing countries, and highlighting the role of governments in achieving a better distribution of incomes, the need for good governance is strongly felt. This study aims to examine the impact of the good governance on income distribution among the South-Western Asia countries during the period from 1996 to 2013. It estimates two panel data models using Stata12 software. In the first model, the index of good governance quality and in the second model, six indicators of good governance are investigated. The results show that the index of governance quality and the indicators of political stability and government effectiveness have negative and significant effects on reducing inequality. Thus, the proper policy-making may improve the distribution of income in these countries.

This research aimed to surveying the influence and critical role that good governance might play with regard to the increasing trends in income inequality, numerous rates of unemployment, lack of economic justice in different societies especially within developing countries, and in carrying out government's duties to achieve a better distribution of income. Hitherto, income distribution has been one of the main concerns of the government. Since the income distribution and social justice are, often, alleged to be associated with poverty issues this might have led to some short-term solutions to fix the problems. On the other hand, scholars in the fields of Economists tend to claim that the phenomenon of inequality of income distribution might be shows some sorts of internal resistance and without considering the effective factors short-term solution might have adverse effects on income distribution and economic growth. In order to deal with the problem of unfair income distribution the effective factors should be identified and appropriate policies should be taken to modify income distribution. This shows the income distribution is as important in the society as almost all the economists highlight income distribution as government's critical goal and task. The presence of good governance and equal income distribution is required to reduce poverty. This signifies the need for good governance and with respect to a result of a two-state models (maximum vs. minimum), one may feel the need for such a good governance.
The present research is a case study with an econometric approach aimed to put the social and economic theories in the field. The causal relationships between variables can be analyzed by using figures. As the current study conducted in some countries and data governance have been publishing since 1996, it is limited to the number of years that series econometrics could not be used for them. Econometric methods using panel data were used to estimate the models. Moreover, time series data was used to estimate the 12-year period from 1999 to 2010 via Eviews8 software.
Findings: According to the results of this research, it can be stated that indicators of good governance have a significant negative impact on the Gini coefficient. Paying attention to governance and quality of governance can increase the economist's ability of explaining the empirical facts. As the advanced countries have high indicators of good governance, transition Countries that seek to improve the economic situation, especially the improvet the income distribution in society, should pay attention to this indicator. The findings indicate that improving any component of governance will make positive changes in order to improve income distribution in selected countries in South-Western Asia and the countries of the Organization for Economic Cooperation and Development (OECD).
This study examined the impact of the governance to reduce inequalities in two countries of South-Western Asia and countries of the Organization for Economic Cooperation and Development during the period from 1996 to 2010 and by using panel data. Many economists believe the improvement of the governance is a fundamental measure to improve income distribution and social welfare. Regarding the findings of this research the government can use such indicators in the successful countries through the improvement of the governance model of good governance (transparency, effectiveness, political stability and lack of violence and terrorism, government effectiveness indicator index terms, index, rule of law and corruption control index). These indicators lead to reducing the cost trade, increasing investment, production and employment, and contribute to reducing income inequality. Since good governance factor driving economic growth, wealth creation and ultimately increase employment and improve income distribution are required studied countries, especially the countries of South-Western Asia have to pay much attention to them. As this indicators of governance situation is not good in the countries of South-Western Asia, in the end, some suggestions offered to improve the situation in this countries. So that good governance is important to reduce inequalities in the distribution of income and long-term performance. Due to the high level of inequality in developing countries, especially the countries of South West Asia it is suggested that politicians and economic managers in these countries, pay more attention to indicators of good governance and use them in order to reduce inequality.

Sometimes due to the inefficient transportation and inspection methods or improper storage، some items sent to the buyer are damaged that they might be reused by some types of remanufacturing. However، the defective items are naturally purchased at a lower price than the perfect ones. In this paper، a mixed-integer linear programming model is proposed for the multi-period joint supplier selection and order lot-sizing problem concerning both the percentage of defective as well as the remanufacturable items in which besides the purchase price، the transportation costs are also discounted according to the number of departure vehicles. The order lot-size is optimized with respect to three factors including the purchase price discount، the capacity of supplier''s vehicles and the carrying costs. To assess the validity of the proposed model، a numerical example from the recent literature is solved through the GAMS modeling language and the sensitivity of the model parameters is analyzed. The results confirm that considering simultaneously the three proposed objectives، i. e.، - purchase costs، transportation and ordering costs، and carrying costs، could result in an decrement of almost 20% in the total costs. Furthermore، suppliers can achieve a more chance of selection by delivery of the smaller percentage of defective items.