morteza gholizadeh

The present research aimed to evaluate the effect of industrial steel fibers on the mechanical properties of reactive powder concrete (RPC). A series of reinforced RPC specimens containing different percentages of steel fibers having different diameters were built. By performing resistance tests on the samples, the mechanical properties (compressive, bending and tensile strengths) of RPC were determined. The results of the compressive tests showed that by increase in the curing age from 7 to 42 days, the strength of RPC containing group 2 steel fibers (medium fibers: diameter 0.6 mm) increases compared to the control concrete. This is attributed to the continued reactions between the cement paste and the interlocking of most of the quartz-silica sand aggregates and micro-silica powder in the RPC specimens with steel fibers. The highest compressive strength of RPC compared to the control concrete was obtained for the sample containing 2% group 1 steel fibers (small fibers: diameter 0.4 mm) equal to 421 MPa (29.11% growth compared to the control concrete). By reduce in the diameter of fibers, the number of fibers in the sample and subsequently the interlocking between aggregates and fibers increases and the replacement distribution of aggregates improves. Based on the flexural strength tests, 2% of groups 1 and 2 steel fibers and 3% of group 3 (large fibers: diameter of 0.8 mm) were determined as the optimal value of fibers to achieve the maximum flexural strength of RPC. Based on the tensile tests, it was found that with the addition of 1%, 2% and 3% of groups 1, 2 and 3 steel fibers, the growth of RPC tensile strength is completely upward. The reason was attributed to the bridging effect of steel fibers in the concrete matrix. Empirical equations obtained from regression analysis have high accuracy for estimating resistance properties.

Reactive powder concrete (RPC) is one of the ultra-high strength concretes with superior mechanical properties, which is made using cement and very fine powder materials such as quartz sand, microsilica, low amounts of water-cement ratio, super-lubricant and steel fibers. The main role of steel fibers in such concrete is actually a type of composite that has proper integrity and continuity and enables the use of concrete as a flexible material. The present study aimed to evaluate the effect of using different types of industrial steel fibers with different length (diameter) and percentages on the strength properties of RPC and to determine a series of experimental relationships for their estimation. To this end, by preparing three types of steel fibers with small diameters (group 1), medium (group 2) and large (group 3) and making a number of RPC samples using indigenous and common mineral materials, the strength characteristics of this type of concrete include compressive, bending and tensile strengths were determined at different ages. To investigate the effect of curing time as well as the diameter and percentage of steel fibers on the compressive strength of RPC, a total of 39 samples + 1 sample without fibers (control concrete) containing 1 to 5% of large steel fibers (with diameter of 0.8 mm), medium (with diameter of 0.6 mm) and small (with diameter of 0.4 mm) were made and their compressive strength was determined at different ages. In addition, to determine the bending and tensile strengths of RPC samples, a total of 18 standard RPC beam and cylindrical samples containing different percentages of medium diameter steel fibers were made. After these samples were cured, their 28-day strength was evaluated in comparison with the control samples. The results of compressive strength tests showed that by increase in the curing age, the strength of RPC increases in compared with the control sample (without fibers). The results of compressive strength tests showed that by reduce in the diameter of steel fibers, the 28-day compressive strength of RPC samples increased significantly and was determined to 423.5 MPa. In compared with the control sample (without fibers), the compressive strength is associated with a growth of 29.11%. Also, the optimal amount of medium steel fibers to achieve RPC with the highest strength was determined to be 2%. The results of flexural strength tests showed that 2% of group 1 steel fibers (with small diameter) and group 2 (with medium diameter) and 3% of group 3 steel fibers (with large diameter) as the optimal percentage of steel fibers to reach the maximum flexural strength in RPC. Therefore, the 28-day flexural strength of RPC samples containing 2%, 2%, and 3% of steel fibers of groups 1, 2, and 3, respectively, was equal to 40.9, 44.6, and 39.1 MPa. The highest tensile strength of RPC samples containing 1%, 2%, and 3% of steel fibers of groups 1, 2, and 3 compared to the control sample, was associated with a growth of 61.25%, 66.42%, and 68.21%, respectively. Also, the results of the tensile strength tests showed that the addition of group 2 steel fibers (medium) compared to the other two groups (small and large), had a greater impact on the growth percentage of tensile strength of RPC samples.

Globally, Iran ranks 6th in natural gas production. Producing over 1 billion cubic feet of dry natural gas, the Gachsaran gas refinery is a major revenue source for the country. Tens of thousands of barrels are sent to the Bandar-e-Emam petrochemical plant every day, and the Gachsaran oil and gas refinery always aims to partially supply the feed for this petrochemical complex by sweetening sour natural gas feed containing some H2S and CO2. Due to the high energy consumption of the sweetening unit, energy optimization of this process is significant. Vapor Recompression Column was used for optimizing sweetening process energy in the Gachsaran gas unit, and the distillation column's top vapor was compressed to transfer its thermal energy to the bottom. The results show that Vapor Recompression Column consumed about 75% less energy than the conventional process mostly due to warm and cold utility savings. The output pressure of the compressor added in this process was calculated accurately. If the compressor output pressure increases excessively, this method becomes inefficient and uneconomical.

Recent studies have clearly demonstrated this fact motivation is directly linked to increased productivity in human resources. Therefore paying attention to employees' motivational factors and their needs is important to ensuring productivity and performance improvement of organizational projects. In a few researches the motivation of human resources and the effect of different factors on the change of motivation and its effect on the time productivity of construction projects have received less attention. Therefore, the aim of this article is to investigate the effect of change of motivation and the factors affecting it on the time efficiency of construction projects with the approach of system dynamics. For this purpose, after identifying the effective parameters on the motivation of human resources, from sampling data using survey studies with questionnaires and interviews, library sources and collecting information. the qualitative modeling and effect loops between parameters were performed with the Vensim software package. Also, the relationships between parameters were determined with the quantitative modeling. In the following, the model was implemented to the real project by defining different scenarios based on changing the effective parameters on the motivation of manpower and the time efficiency of office-commercial building project. The results showed that if there is a 50% increase in manpower motivation in the project, the correct rate of work is increased up to 3 times and the project takes 690 days and 30 days. The results also show that a 50% reduction in salary increases the delay in completing the project by about one year and a 20% delay in payment of salaries leads to an increase in project completion of up to 4 months and an increase in the ratio parameter. Wages will be reduced by up to 2 times 5 months after the completion of the project.

The role of human resources in reducing human resource risks and, consequently, organizational risks and organizational profitability, is an undeniable and very important role, and the role of human resources is something beyond administrative and office roles, which unfortunately this view There is a role for human resource management in most project-oriented organizations and so far the risk of strategic human resource actions, especially in the country's manufacturing industry projects has not been systematically assessed.The present paper aimed to identify the risks affecting human resource management in construction projects and provide an integrated model based on Adaptive Network-based Fuzzy Inference System (ANFIS) for risk assessment. By determining the probability, severity and rate of occurrence of risks, a total of 9 risk factors including (1) lack of maturity and knowledge of specialized staff, (2) job stress, (3) employee motivation, (4) lack of attention to the management process Performance and feedback, (5) lack of financial resources to reward innovative activities, (6) inappropriate payment policies, (7) discriminatory performance between human resources, (8) lack of technical knowledge and skills, and (9) lack of Possession of trust-building skills among employees was identified as critical (unauthorized) risks. The results of correlation coefficient criteria to determine the error value of the two methods presented showed that random data had a higher correlation coefficient than the actual data of experts and the results were satisfactory with high accuracy. Also, qualitative and quantitative analysis of risks by ANFIS method and based on experts' opinions and random data showed that if the risks are not available in projects that are being implemented for the first time or access to the required number of experts, by adopting and selecting appropriate random input data. Fuzzy intervals, instead of experts' opinions and their analysis by ANFIS method, obtain acceptable results.

The purpose of this study was to investigate the effect of service quality variables and perceived fair price on customer satisfaction directly and indirectly through the company image. Based on theoretical and empirical background, the conceptual model of the research is formulated in four hypotheses. The statistical population is the users of the Irancell Company in Iran and Turkcell in Turkey, the sample was selected among them by simple random method. The sample size is 315 for Irancell Company and 295 for Turkcell Company. The data gathering tool was an electronic questionnaire and its content validity was confirmed by CVI and CVR methods. Also, its reliability was confirmed by Cronbach's alpha coefficient. SPSS and Smart PLS software were used to analyze the data. The results of the research showed that the quality of perceived service has a positive and significant effect on customer satisfaction either directly or indirectly and through the image of the company. The results also showed that fair price perception directly and positively affects customer satisfaction, but its indirect effect was not confirmed by the mediating role of the company's image. Finally, using T-test two independent samples, the average customer satisfaction was compared with Irancell's operators in Iran and Turkcell in Turkey. The results show that there is no significant difference in customer satisfaction with the services of these companies.

In this study, the effect of various factors on the permeability of CO2 and O2 gases on light polyethylene can be investigated. temperature, gas pressure and polymer thickness factors affect the permeability of gases. Various models such as DSC model and a device with ASTM standard and barometric method were used in the measurements. the results of the mentioned models show that with increasing temperature, the coefficients of permeability and permeability and solubility increase. also, increasing the pressure reduces the passing coefficient by a certain amount. But after a certain amount, the increase in pressure does not work. also, increasing the pressure has no effect on the permeability coefficient. In the case of solubility coefficient, increasing to a pressure range reduces this coefficient, then reaches a constant value.