yaser ahmadi

The purpose of this research was to analyze the effect of ownership concentration on the relationship between the level of social responsibility disclosure and the company's reputation. The research method was quantitative-inductive. The statistical sample includes companies admitted to the Tehran Stock Exchange between 1397 and 1401, for 5 years, which included 150 companies and 750 years of observation. A single model was selected to estimate the two hypotheses and its results were confirmed at a confidence level above 99%. The regression test was performed with Eaviz software and the normality of the distribution and the reasonableness of the error were ensured. The hypotheses were confirmed with a minimum confidence level of 99. The result is that the concentration of ownership is effective on the level of corporate social responsibility disclosure on the company's reputation. In fact, with the concentration of ownership, it is possible to make a better decision and implement it quickly. Finally, to confirm the effectiveness of social responsibility disclosure level.

The expansion of women's presence in social scenes today has even reached high-ranking political officials. In the corporate scene, there is a debate about how effective the presence of women in the board of directors is on its management. This research was carried out in a quantitative-inductive way and its purpose is to investigate the effect of the presence of women on the board of directors of companies listed in the Tehran Stock Exchange on the cost of ownership rights and then to study the role of information asymmetry moderator on it. 150 companies were selected from among the mentioned society that were active between 1395-1401, which ended in 1050 years of observation. While trusting the research models at a level above 99%, none of the research hypotheses were confirmed. The result is that due to the strictness of the audit of the stock exchange organization on the membership of the companies, the financial statements have been standardized, as a result of which, information asymmetry and the cost of ownership rights have reached their minimum and have become independent from the composition of the board of directors. In fact, the board of directors has very limited authority to influence the mentioned variables and therefore the presence of women cannot help them.

The results of the research showed that there is a negative and significant relationship between managers' narcissism and financial performance (measure of asset return and company's market value) that these results confirm the financial-behavioral theory, which means that usually managers with high narcissism systematically lower future returns due to He overestimates the investment projects and overestimates the effect of favorable events on the company's cash flows and underestimates the probability and effect of unfavorable events on the company's cash flows. Therefore, managers with overconfidence usually have higher capital expenditures. and have weaker financial performance, and the results of this research also confirm that the narcissism of managers causes a decrease in the financial performance of companies. Also, the results showed that the presence of a powerful board of directors on one hand increases financial performance and on the other hand it moderates and reduces the negative relationship between managers' narcissism and financial performance of companies, which indicates the supervisory role of these managers in line with agency theory. And the corporate governance mechanism is strong. In other words, by increasing the independence and the size of the board of directors and the amount of ownership of managers, the opportunistic behavior of CEOs and their narcissism and unilateral and arrogant decisions are reduced, and as a result, the stock value and financial performance of the company increases. This result means that the role of a powerful board of directors in Iran is in accordance with the agency theory and the ability of this supervisory tool to reduce opportunistic behavior and behavior caused by narcissism and false self-confidence of CEOs is strong.

Examining the impact of stability of Earnings components on audit costAbstract:The "opportunistic" perspective highlights the possibility that managers engage in earnings component sustainability as an opportunistic behavior. This view suggests that the persistence of earnings components is used to obscure information about firms' actual economic performance, which can lead to earnings obscuration and value erosion. And since the business risk of a company (i.e., the client) determines the audit fee, the stability of profit components may have a favorable effect on auditors' pricing decisions and lead to lower audit costs. On the other hand, the persistence of earnings components can be used by managers to intentionally hide information about the firm's true economic performance, which can increase the likelihood of firms engaging in opportunistic earnings management and intentional financial misreporting. Therefore, this research examines the impact of the stability of profit components on audit costs in companies listed on the Tehran Stock Exchange. To conduct this research, a sample of 103 companies was selected from the companies accepted in the Tehran Stock Exchange.In this research, the effect of stability of profit components on audit cost in companies listed in Tehran Stock Exchange for the period of 1396 to 1401 was investigated, which has a total of 618 observations available for research. The statistical method used in this research is the multivariate regression method using panel data. The results of the research hypotheses indicate that there is an inverse relationship between the stability of profit components and audit costs.

Recently nanoparticles are used for improving the volume of oil and gas production and Enhanced Oil Recovery (EOR) purposes. Based on our recent researches, using nanoparticles such as Silica and Calcium oxide has a good potential for changing mechanisms in the porous media such as interfacial tension and wettability. For finding the application of nanoparticles in the porous media, low permeability carbonate plugs were selected, and two main steps were used , including 1) Using CaO and SiO2 nanoparticles for wettability alteration, interfacial tension reduction, and improving fluid flow through porous media 2) Surveying the application of nanoparticles on the water alternative gas (NCs assisted WAG) test. The Zeta potential amounts are stable at condition of -56.4±2 mV and -44.0±3 mV for Calcium oxide and Silica nanoparticles, respectively at optimum nanoparticles concentration of 15 ppm. Calcium oxide and Silica nanoparticles have effectively altered the wettability from oil-wet to water-wet by surveying the intersection of two-phase relative permeability. Moreover, CaO nanoparticles had better performance in low permeability carbonate porous media than SiO2 nanoparticles with regards to wettability alteration to water wet. Based on the results and better version of CaO, it was selected for performing NCs assisted WAG tests at WAG ratios of 1:1, 40 ℃, and 15 ppm.The recovery factor was increased from 42.9 % to 73 % in the presence of CaO during performing NCs assisted WAG tests, and residual oil saturation was decreased from 40.9 % to 19.4 %.

The purpose of this research is to investigate the effect of managerial ability on corporate tax risk and long-term tax avoidance in companies listed on the Tehran Stock Exchange. The current research is an applied research from the perspective of the result of its implementation, from the perspective of the goal of conducting an analytical research (correlation method), from the perspective of the logic of conducting a comparative-inductive research, and from the perspective of the time dimension, it is a longitudinal research (post-event). In line with the aim of the research, data related to 180 companies admitted to the Tehran Stock Exchange during the years 2014 to 2014 were examined. To test the hypotheses, multivariate regression model and Eviuse software version 13 were used. The results showed that management ability increases tax risk and long-term tax avoidance. Capable managers can better align their business decisions with tax strategies and can easily use the opportunities created for tax planning in order to increase the company's efficiency due to their high understanding of the company's operating environment.

The Rock-Eval pyrolysis is a thermal method that is widely used by the petroleum geologist for evaluation of source rock characteristics and obtain geochemistry parameters. However, there are misconceptions and misuses in exceptional cases that could lead to erroneous conclusions after using the Rock-Eval pyrolysis data to evaluate the properties of organic matter. However, a cross-plot of S2 (petroleum potential) versus TOC (total organic carbon) is the usable tool to solve issues and applied for checking the accuracy of the geochemistry parameters. The graph provides the correction criteria for the S2, HI (hydrogen index), and kerogen type. As well as, the graph measures the adsorption of hydrocarbon by the mineral matrix. In addition, this article demonstrates a manner based on the data plot of S2 versus TOC to detect bitumen or hydrocarbon contaminations. Based on our knowledge about the Garau Formation as a possible source rock in petroleum geology of Iran, a geochemistry study by Rock-Eval VI pyrolysis and Leco Carbon Analyzer has been conducted on many rock samples collected from different outcrops in the Lurestan province, Aligudarz region, from South-West of Iran, High Zagros. Plotting the data on a cross plot of S2 versus TOC, drawing the regression line, and finding the regression equation are the best method for determining the real values of S2 and HI parameters and bitumen/hydrocarbon contamination. Contamination creates a y-intercept in the graph of S2 versus TOC which makes geochemistry data unreliable in two study location. As, led to the S2 and HI data unrealistically increased, while the Tmax values went down and reduced the thermal maturity of the organic matters from its real status. For skipping the effect of contamination and obtaining the real geochemistry parameters, the y-intercept of the graphs removed and the corresponding values subtracted from the HI and S2. The cause of contamination in the Garau Formation is the adhesion of heavy bitumen to organic facies due to the covalent bonds between carbon and hydrogen ions

This study investigates the effect of new nanocomposites (ZnO/SiO2/Xanthan) for the most appropriate selection of nanocomposites concentration in sandstone porous media. This study has been done for the first time in sandstone reservoir. First, the morphology of nanocomposites was investigated using XRD, SEM tests. Then, the effect of nanocomposite on changes in wettability, surface tension, viscosity, zeta potential, pH, and density in different concentrations of nanocomposite in tank conditions was investigated. Based on the results of this study this study, the optimal concentration was selected for fluid dynamic tests. The optimum choice of fluid can reduce many problems, such as reducing oil recovery due to blocking the pores and throat of rocks. According to lowest contact angle (36°), highest zeta potential (-49.68 mV) in the presence of nanocomposites, 40 ppm was chosen as the optimum concentration.

The Rock-Eval pyrolysis is a thermal method that is widely used by the petroleum geologist for evaluation of source rock characteristics and obtain geochemistry parameters. However, there are misconceptions and misuses in exceptional cases that could lead to erroneous conclusions after using the Rock-Eval pyrolysis data to evaluate the properties of organic matter. However, a cross-plot of S2 (petroleum potential) versus TOC (total organic carbon) is the usable tool to solve issues and applied for checking the accuracy of the geochemistry parameters. The graph provides the correction criteria for the S2, HI (hydrogen index), and kerogen type. As well as, the graph measures the adsorption of hydrocarbon by the mineral matrix. In addition, this article demonstrates a manner based on the data plot of S2 versus TOC to detect bitumen or hydrocarbon contaminations. Based on our knowledge about the Garau Formation as a possible source rock in petroleum geology of Iran, a geochemistry study by Rock-Eval VI pyrolysis and Leco Carbon Analyzer has been conducted on many rock samples collected from different outcrops in the Lurestan province, Aligudarz region, from South-West of Iran, High Zagros. Plotting the data on a cross plot of S2 versus TOC, drawing the regression line, and finding the regression equation are the best method for determining the real values of S2 and HI parameters and bitumen/hydrocarbon contamination. Contamination creates a y-intercept in the graph of S2 versus TOC which makes geochemistry data unreliable in two study location. As, led to the S2 and HI data unrealistically increased, while the Tmax values went down and reduced the thermal maturity of the organic matters from its real status. For skipping the effect of contamination and obtaining the real geochemistry parameters, the y-intercept of the graphs removed and the corresponding values subtracted from the HI and S2. The cause of contamination in the Garau Formation is the adhesion of heavy bitumen to organic facies due to the covalent bonds between carbon and hydrogen ions.

Using nanoparticles for adsorbing asphaltene was known as one of efficient methods among researchers for upgrading of real oil samples in comparison to other expensive mechanical treatments or even solvents (such as n-pentane and n-heptane) and surfactants. In this study, Nickel zeolite oxide nanoparticles have been used for asphaltene adsorption and solving asphaltene precipitation problems. Although Nickel zeolite oxide nanoparticle used in previous studies as an asphaltene adsorbent, observing relation between asphaltene adsorption on its surface and asphaltene precipitation in the presence of nanoparticles was not covered. Series of experiments include FTIR, CO2-oil IFT tests, Langmuir and Freundlich isotherm models, and natural depletion tests were performed in the presence of Nickel zeolite oxide nanoparticles. Adsorption data was fitted well with the Langmuir model in comparison to the Freundlich model which shows that the adsorption occurs in a homogeneous surface with monolayer coverage. Based on the CO2-oil IFT results, there are two different slope forms in IFT readings as pressure increase from 150 Psi to 1650 Psi. Second slope (900 Psi-1650 Psi) is slower than the first one (150 Psi-900 Psi) which was due to aggregation of asphaltene. Three pressures of 1350 Psi, 1500 Psi, 1650 Psi and Nickel zeolite oxide nanoparticles at concentration of 30 ppm were selected for performing natural depletion tests and the basis of selection was high efficiency of adsorption in these points. As pressure decrease from 1650 Psi to 1350 Psi, asphaltene precipitation changes from 8.25 wt % to 10.52 wt % in the base case and it was 5.17 wt % to 7.54 wt % in the presence of Nickel zeolite oxide 30 ppm. Accordingly, Nickel zeolite oxide nanoparticles adsorbed asphaltene on its surface in proper way and the amount of asphaltene precipitation was decreased in the presence of Nickel zeolite oxide nanoparticles.

One of the important issues in oil industry is related to asphaltene precipitation during different stages, and using nanoparticles is known as a common method for solving this problems. Although nickel oxide and zeolite have been addressed in previous researches for solving asphaltene precipitation problem, Using NiO/Na-ZSm-5 (the main goal of this study) has not been developed for solving relevant asphaltene precipitation problem. The crystalline structure and morphology of the synthesized nanoparticles have been analyzed with the help of XRD, SEM, FTIR and EDX. Results show that the nanoparticles were well synthesized and after synthesis with a diameter of 13.6 nm. The EDX analyses also approved that an amount of asphaltene was adsorbed by the sorbent. Asphaltene adsorption experiments were carried out at various asphaltene concentrations and different temperatures and the effect of different variables of initial asphaltene concentrations, temperature and ratio of heptane to toluene were evaluated on asphaltene adsorption rate. The results indicate that with an increase in the initial asphaltene concentration from 25 to 2000 ppm, the asphaltene adsorption rate in zeolite increases. In concentrations less than 500 ppm, a rise in temperature results in reduced asphaltene adsorption, while at concentrations higher than 500 ppm, with a rise in temperature from 25°C to 55°C, asphaltene adsorption capacity on zeolite increases. Also greater adsorption has been observed for Heptane/Toluene=0.4 with q=25.17 mg/g. For determining the kinetic mechanism of this process, the experimental data were adapted according to Lagrangian pseudo-first and second-order models. The Langmuir and Freundlich adsorption isotherms were evaluated, in which the isotherms resulting from the Langmuir isotherm model were of adequate conformity. This indicates that adsorption at the homogenous level occurred with single-layered coating. In the final step, after evaluating the thermodynamic conditions, the spontaneity of the asphaltene adsorption process was proven.

Earning is one of the most important accounting information as well as a criterion for assessing financial reporting and has always been considered by the various interest groups in the company. Because the change in the balance sheet figures occurs due to the change in the profit and loss statement figures. The existence of an accrual accounting basis has led investors and financial analysts to focus on the quality of their earnings in addition to reported earnings values in determining the company's value. Hence, earnings persistence is one of the important indicators of earnings quality. From the perspective of investors, the earnings that is more stable, the earning is defined by the quality. Therefore, managers as top-level organizations have the power and authority to make decisions and influence financial reporting. As a result of their opportunistic behavior with excessive earning manipulation and confidence, they rely on their own beliefs to reduce their reliance on information and reduce the quality of earning. In this regard, the present study first explores the relationship between the Earnings forecast error and earning persistence in earning management. Then, in the following, the effect management overconfidence on the above relationship has been examined over a 9-year period from 2009 to 2017 in 115 companies from listed companies in Tehran Stock Exchange. The results of this study show that there is a significant and positive relationship between Earnings forecast error and the earning persistence in earnings management, also the overconfidence has a different significant effect on them.

Earning as the most important product of the accounting information system should be of an acceptable quality. Because earning is the basis of the economic decision-making of investors. Investors tend to have information about the future, including the prediction of earnings per share and its precautionary prediction. However, managers' opportunistic behavior by manipulating earnings reduces the reliance on information and reduces the quality of earning. In contrast to accounting conservatism, the manager's biased behavior in identifying earnings is delayed. Hence, the conservatism makes the manager and other groups, such as shareholders, receive less sums of return. This will increase the value of the company. The increased value of the company increases among all the parties in the company's division of the division and welfare of each group. Hence, this research examines the effect of earnings management on the relationship between earnings forecast error and accounting conservatism in a period of 9 years from the over a of 2009 to 2017 in 115 companies from listed companies in Tehran Stock Exchange. The results of the research show that there is a significant (positive) relation between the predictive error of earning and the accounting conservatism (as one of the criteria of the quality of earnings) in the real earnings management. But the results of this research do not confirm the significant relationship between the predictive error of earnings and accounting conservatism in accruing earnings management.

To our knowledge, no study is available on the relationships between otolith mass and age as well as body weight and length of Chondrostoma regium (Heckel, 1843) in the Zayandeh River, hence the present study attempted to examine this rather simple, efficient and cost-effective approach to contribute in providing more objective information required in age-related studies of this species. During March-April 2017 random samples of C. regium were collected by a river seine in the Zayandeh River. Sampled fish ages were between 2 to 5 years and ranges of total length, body weight and otolith mass averages of samples were 82.2-161.6mm, 5.35-42.35g and 4.1-7.3mg, respectively. As the fish grow, total length, body weight and otolith mass averages showed a clear increasing trend. The results revealed significant positive relationships between variability of body length and otolith weight (P<0.05) as well as variability of body weight and otolith mass (P<0.05) of C. regium. Furthermore, an obvious significant increasing trend of otolith mass with age increment (P<0.05) is found. The average weights of otoliths in the present study increased with age, length and weight which evidently confirms that the otolith mass increase in C. regium is in compliance with somatic growth through the ontogenetic processes.

This paper addressed the application of new hydrophobic synthesized calcium oxide (CaO) and silicon dioxide (SiO2) nanofluids to low permeability carbonate porous media. Crude oil and plugs were selected from one of oil reservoirs in the west of Iran. The main goal of this paper is comparing the results of improving water-oil relative permeability parameters in low permeability plugs of carbonate cores in the presence of new synthesized CaO and SiO2 nanofluids. All the experiments were performed at a temperature of 40 °C and at a nanoparticle concentration of 45 ppm. The experimental approaches were designed into two main steps: 1) the effects of both nanoparticles on the changes in interfacial tension (between oil and brine) and oil viscosity 2) the effects of both nanoparticles on wettability (qualitatively) and relative permeability parameters. SiO2 and CaO decreased interfacial tension from 46.414 mN/m to 41.772 mN/m and 32.860 mN/m respectively. Moreover, SiO2 and CaO decreased oil viscosity from 9.90 cP to 8.61 cP and 8.01 cP respectively. Based on the obtained results in the core flood experiments, although CaO and SiO2 nanofluids decreased effective water permeability, effective oil permeability and ultimate oil recovery increased. Moreover, it was seen that the CaO nanofluid improved oil flow in carbonate cores more than the commercial SiO2 flooding. Finally, it was seen that both nanoparticles change the wettability from oil-wet to water-wet (qualitatively).

The purpose of this study was to explore the purchase behavior of male physical education students toward foreign brand sports shoes available in Iran’s market. The present study is of a descriptive-correction type. The statistical population consisted of all male physical education students of Mashhad universities (n=900) of which 270 participants were selected using Cochran’s sample size formula. The sampling method used in this study was proportionate stratified sampling. A questionnaire utilized by Lee et al. (2008) was used for data collection. The validity of the model and the relationship between research variables were approved by Structural Equation Modeling (SEM). The results showed that normative group has a significant impact on consumers’ brand awareness. On the other hand, brand awareness has a positive impact on both emotional value  and perceived quality of foreign brand sports shoes. The results also revealed that increased consumer brand awareness leads to an increase in purchase intention. Among the dimensions of the studied brand in this research, both perceived quality and emotional value had significant and positive impact on male physical education students’ purchuse intention toward foreign brand sports shoes, while the impact of emotional value was more than perceived quality.

The purpose of this paper is to explore the impact of individual characteristics and brand-specific features and finally designing a Model of consumer purchase behavior toward Foreign brands of Sports apparel that are available in the Iran market The statistical population of the study consisted of Sports experts. The research sample size is equal to the population size and the census is taken. A questionnaire was used to collect the data, are used by Kumar et al, Which Validity of the model and the relationship between the studied variables was approved by the techniques of Structural equation Modeling. The results show that Self-concept of individuals has no role in their orientation toward domestic brands of Sports apparel, but need for uniqueness have been effective on individual’s orientation toward brand. On the other hand, brand orientation has also positive impact on both emotional value and perceived quality of domestic brands of Sports apparel. Also according to results, increasing brand orientation, not increase their purchase intention. All dimensions of brand in this study, both perceived quality and emotional value have significant positive impact on consumer’s purchase intention toward domestic brands of Sports apparel. Domestic manufacturers must develop their own brand products, also Sports apparel sellers have to offer in their stores are foreign brands

This study investigated the age and growth of Chondrostoma regium in upstream of the Zayandeh River by using different calcified structures (i.e. scale, otolith and vertebra). Also, the potential variability of age and growth estimates derived from different structures and their competency for further applications in population and life history studies of this species were statistically evaluated and compared. Based on the aging performed by using different calcified structures, C. regium specimens composed of 4 age groups of 2 to 5 years. Considering all aging structures (i.e., scale, otolith and vertebra) the major proportion of the sample was those within the age groups of 3 and 4. The von Bertalanffy’s growth models of C. regium was fitted separately for the data derived from each of the aging structures. Among all the fitted models, the scale-based model showed the smallest measures of the information criteria with AIC=296.88 and SBC=300.86. Based on all the statistical indices for model comparison, the von Bertalanffy’s growth model using the direct scale-based observations showed the most reliability and the best performance for growth parameters estimation of C. regium in this study. Hence, for C. regium inhabiting upstream of the Zayandeh River the most statistically sound von Bertalanffy’s growth equation could be written as Lt=303 (1-e–0.11 ( t–(-0.34))). Given the importance of growth studies in effective management and conservation of native fish populations as well as considering the highly changing and under pressure environment of the Zayandeh River, our study attempted to provide updated information on growth characteristics of C. regium in this aquatic ecosystem. The results of this study may help to improve our understanding of its population dynamics and may provide help in designing better conservational plans for this native species.

In many reservoirs, after water flooding, a large volume of oil is still left behind. Hot water injection is the most basic type of thermal recovery which increase recovery by improved sweep efficiency and thermal expansion of crude.In the present work, the effects of injection rate and the temperature of the injected water were surveyed by using core flooding apparatus. Water flooding was performed at different rates (0.2, 0.3, and 0.4 cc/min) and temperatures (20 and 90 °C), and the reservoir temperature was about 63 °C. Oil recovery during hot water injection was more than water injection. Moreover, it was concluded that at injection rates of 0.2, 0.3, and 0.4 cc/min breakthrough time in hot water injection occurred 10 min later in comparison to water injection. The results showed that higher oil recovery and longer breakthrough time were obtained as a result of reducing injection rate. In the first 50 minutes, the oil recovery at injection rates of 0.2, 0.3 and 0.4 cc/min was 27.5, 34, and 46% respectively. It was found that at the beginning of injection, thermal and non-thermal injection recovery factors are approximately equal. Moreover, according to the results, recovery factor at the lowest rate in hot water (T=90 °C and q=0.2 cc/min) is the best condition to obtain the highest recovery.

Iranchr('39')s apparel market is currently filled with foreign brands that are generally ranked as high quality goods with high prices. With a surface examination of the apparel market and customers’ opinions, it can be concluded that Iranian apparel, despite having lower prices, is not in a suitable status in comparison with its foreign counterparts. Accordingly, the purpose of this paper is to explore the impact of individual characteristics and brand-specific features, and finally design a model of consumer purchase behavior towards domestic brands of sports apparel that are available in the Iran market. The method of this study is descriptive-correlational and in terms of the aim, is applicable. The statistical population of the study consisted of sports experts. 141 individuals as sample size were studied out of 220 individuals of the population. A questionnaire used by Kumar, Kim, and Pelton (2009) was also used to collect the data, and the validity of the model and the relationship between the studied variables was supported by the techniques of structural equation modeling. The research findings showed that self-concept of individuals has no role in their orientation towards domestic brands of sports apparel, but need for uniqueness was effective on individual’s orientation towards brand. On the other hand, brand orientation also had positive impact on both emotional value and perceived quality of domestic brands of sports apparel. Also, according to the findings, increasing brand orientation did not increase their purchase intention. All the dimensions of brand in this study, both perceived quality and emotional value had significant positive impact on consumer’s purchase intention towards domestic brands of sports apparel.

This study examines the relationship between the cash conversion cycle and return on assets in this company from (1382) through (1390).in this research we study the effect of different variables of cash conversion cycle on profitability in this company. these variables consist of: Account Payable period,Inventory Turnover Period,Account Receipt Period. Current ratio, debt ratio, sales growth was considered as a control variable. For analyzing datas and accepting or rejecting each hypothesis we use from pearson and regresun correlation coefficient also we use that for normality. The conclusion of this study shows an inverse relationship between variables of cash conversion cycle and return on assets. it means if account receipt, cash conversion cycle and period of debt payment increase ,the profitability of this company will decrease so managers can create the positive value for shareholders with decreasing period of debt payment, period of inventory turnover, period of demand collection and…