Showing 12 results for Chitsaz
Volume 2, Issue 3 (12-2013)
Abstract
Separate or combined effects of inulin and mannan oligosaccharide supplements on the growth, survival, body composition and salinity resistance of kutum roach (Rutilus frisii kutum) fry (410 ± 19 mg) were investigated for 45 days in 40-liter tanks containing 30 individuals. Fish were fed 7 to 12% body weight with a commercial diet (35% protein and 12% lipid) supplemented with 0 (control), 5 g kg-1 inulin, 5 g kg-1 MOS and 2.5 g kg-1 inulin + 2.5 g kg-1 MOS in a totally randomized design trial in triplicate. A general enhanced growth performance and feed efficiency were observed in fish fed on diet containing 5 g kg-1 MOS (p<0.05). There were no significant differences in survival rate among treatments (p>0.05). NO significant difference was observed in body composition, but protein and lipid contents in the whole body increased in fish fed with 5 g kg-1 MOS and control group. In general, the fish fed 5 g kg-1 MOS had the highest survival index after 48 hours exposed to salinity stress (15 ppt). Results showed 5 g kg-1 MOS could improve growth performance, survival and salinity stress resistance of kutum fry.
Volume 7, Issue 26 (6-2019)
Abstract
Among the various types of oral literature and due to their richness, tales and myths have the ability to examine the origin and effects of anthropology, sociology, psychology, etc. Some sociologists believe that their knowledge of the institution of the family in Iran's past is negligible. Therefore, history, especially folktales, can illuminate parts of social life that are far from the eyes of sociologists. The question of power is one of the subjects of interest in sociological studies in family institution. Understanding the distribution of power within the family in past periods represents a lot of social change. In this article and in order to examine the power structure within folklore tales; the structure of power, its methods of action and the type of resistance in front of power, as well as the sources of power production in family relationships, were examined in 93 kinds of folk narrative using content analysis approach. The results showed that the power structure in family is highly dominant and is represented in terms of paternity in relation to the child. In relations between men and women, in addition to domination, there is an intimate and legitimate relationship that women accept based on traditional ideologies, the power of men even in intimate relationships. The methods for exercising more power are forced, but the type of resistance, especially girls 'resistance to domination, and boys' active resistance to the father for passive reasons are evident. Gender-related beliefs, socio-economic resources and tips, such as the child's tone and hints, are among the sources of energy production in the family.
Volume 12, Issue 3 (12-2022)
Abstract
Employees' creative ideas are the source of new insights and products that enrich daily life and make a valuable contribution to business development. In other words, employee creativity is the result of interaction between individual and contextual factors with the environment; Also, the source of creativity and innovation is at the intersection between skills and knowledge of the individual and the study of this issue requires the study of internal and environmental triggers in the context of the organizational environment. In this study, which is focused on the role of financial rewards in enhancing the performance of new business/venture ideas in a High Tech ICT Accelerator in China, 168 volunteers employees at this accelerator participated in an empirical experiment. To explore the different interventions of continuous reward allocation in an idea generation process for creating new venture ideas, we defined three forms of maximum, random, and null (control group) types of reward in the experiment. The results of this study show that the allocation of financial rewards improves the performance of idea generation, but also in the lack of reward allocation into the idea generation process reduces creativity and innovation in this field.
Volume 12, Issue 4 (3-2023)
Abstract
The purpose of this research is identifying competencies of Imam Sadiq University (PBUH) faculty members and prioritizing indicators of identified competencies. In order to do this research, the Mixed method (Qualitative → Quantitative) was used. At first, to identify competencies, semi structured interview was conducted with 23 best-performance faculty members of different faculties who were among top ten faculty members in 10 semesters sequentially and competencies were identified by using Thematic Analysis method. Then, extracted indicators from these interviews in the form of questionnaire were given to faculty members that 23 of them completed it. By conducting IPA, the priority of these indicators was revealed. By doing this research, the competencies of Imam Sadiq (PBUH) University faculty members were classified in three levels. These competencies consist of five dimensions, 16 components and 60 indicators. The dimensions of these identified competencies are research, training, educating, operating and personal dimensions. At the end, IPA method was conducted on these identified competencies and priority of competency indicators was identified.
Volume 14, Issue 1 (6-2024)
Abstract
Employee turnover is one of the most important challenges of organizations, which neglecting it can bring a lot of costs to the organization. An important part of the factors that influence the act of leaving the service of employees are known as factors that form the intention or intent to leave the service in employees, which can be called as antecedent factors. The aim of this study is to systematically conceptualize employee turnover with an emphasis on antecedent factors using metacomposite method. In this study, 175 studies that investigated the factors of employees leaving the service were identified and analyzed. The findings of this study showed that the antecedent factors of employees leaving the service can be placed in three general categories: a) Individual factors: including demographic factors of employees; mental and psychological capital; Career Success; b) job factors: including job satisfaction; Organizational Commitment; Quality of working life; c) organizational factors (internal and external): including macroeconomic factors; work experience in the organization; work-family relations; Organizational support; Organizational justice and finally communication with the manager. These factors can directly (such as the quality of work life) or indirectly (such as lack of job satisfaction) affect the act of leaving the service of employees. This study emphasizes the importance of paying attention to the antecedent factors of employees leaving the service. Managers and organizations can prevent the actual leaving of employees by identifying and eliminating the factors that lead to leaving the service and save themselves from serious challenges in the future.
Mahzad Chitsaz, Mani Fathali,
Volume 17, Issue 12 (2-2018)
Abstract
In this article, the impact of external constant and uniform magnetic field is investigated on the mixing efficiency and also geometric and dynamic characteristics of two-dimensional isotropic MHD flow. For this purpose, the direct numerical simulation (DNS) is applied to two-dimensional incompressible magneto-hydrodynamic equations by pseudo-spectral method. Calculations show that external magnetic field causes deformation of vortexes and this deformation is increased by intensification of magnetic field. The dynamic characteristics of flow are affected by these deformations. Investigation of mixing efficiency shows that increase in magnitude of magnetic field or decrease in magnetic diffusivity coefficient causes mixing efficiency to reduce. For explore of the factors affecting on mixing reduction, small and large scale vortexes are studied. Investigation of external magnetic field effect on dissipated energy rate that is associated with changes in the dynamics of small vortexes shows that viscose dissipated energy rate is reduced in the presence of magnetic field compared to its absence. However results show that total dissipated energy rate is increased compared to no magnetic field presence. In order to demonstrate of large scale vertex dynamics, total kinematic and magnetic energy are considered. It is shown that in the presence of external magnetic field, energy is transferred from flow field to magnetic field due to Lorentz force that both leads to reduction of mixing efficiency.
Parisa Mojaver, Shahram Khalilarya, Ata Chitsaz Khoyi,
Volume 18, Issue 3 (5-2018)
Abstract
In the present study, a novel integrated system containing biomass gasifier, sodium high-temperature heat pipes, and solid oxide fuel cells is introduced. The integrated system is taken into consideration due to its high efficiency and power in order to simultaneous producing electrical power and heat. The modeling of system is performed using equilibrium constants, mass and energy conservation law and the analysis of codes is done in EES software. The effect of gasifier STBR, current density, fuel utilization factor, and outlet fuel cell’s temperature as variable parameters is investigated on the power and total energy efficiency of integrated system using response surface method; after validation of modeling in comparison to the experimental results. The analysis of variance results indicate that fuel utilization factor (with 53% contribution) and current density (with 33% contribution) are the most effective parameter on the power and total efficiency, respectively. The power of integrated system is increased by increasing of temperature while power has an increasing behavior follows by decreasing behavior by increasing fuel utilization factor. The total efficiency is increased by increasing temperature and STBR while it is decreased by increasing current density and fuel utilization factor. The results revealed that the power and total efficiency is obtained at optimum states as high as 300 kW and 90%, respectively.
, Saeed Chitsaz, Mir Mohammad Ettefagh,
Volume 18, Issue 6 (10-2018)
Abstract
In this paper, a linear dynamic model of simply supported Above-Ground pipeline during pigging process has been developed and verified by experimental tests. The PIG (Pipeline Inspection Gadget), is an internal moving sprung mass pushed by the fluid pressure, which itself act as a flowing varying mass. The governing equations of motion for the system including the pipeline, moving PIG as a moving vibrational sub-system, and flowing fluid with varying mass were obtained using Hamilton’s principle. Then, the extracted equations were discretized and solved via finite element method. Modal parameters of the pipeline system were calculated during intermittent passage of PIG through the pipe under different fluid flow rates, and their variations were extracted. Validation of the model was carried out using an experimental setup, including a 2.5 meter length Carbon Steel pipe, a simple bi-directional PIG with rubber discs and a centrifugal pump, connected to a control valve, providing required fluid pressure to push the PIG through the pipe. Using data acquisition system to acquire the vibration signals, and employing experimental modal analysis, frequency responses of the system at different points were obtained and the modal parameters were extracted and compared to that of the simulated model. A comparable results have been achieved between theoretical and experimental methods. Also variation of the system natural frequency versus speed and position of PIG in the pipe, were investigated. Moreover, the displacement of the mid-span of considered pipe during pigging process has been obtained using suggested theoretical model.
Naghi Aghazadeh, Shahram Khalilarya, Samad Jafarmadar, Ata Chitsaz Khoyi,
Volume 18, Issue 7 (11-2018)
Abstract
In this article, a new power, cooling and heating cogeneration system consisting of a solid oxide fuel cell (SOFC) - gas turbine (GT), a heat recovery steam generator (HRSG), Generator-Absorber-heat eXchange (GAX) absorption refrigeration cycle and a heat exchanger for heat recovery (HR) has been studied from a thermodynamic and economic perspective. The modeling of this cycle was done by solving the electrochemical, thermodynamic and exergoeconomic equations for fuel cell and system components, simultaneously. The results showed that the exergy of our proposed combined cycle is 14.9% more and the irreversibility rate of this cycle is 10.6% less than that of the combined SOFC-GT-GAX systems in the same conditions. Also, the fuel cell and the afterburner have the highest rate of exergy destruction among other components due to irreversibility. Exergoeconomic analysis showed that the sum of uint cost of products (SUCP), the exergoeconomic factor, the capital cost rate and the exergy destruction cost rate for the overall system is equal to 331.1 $/GJ, 29.3%, 10.47 $/h and 25.32 $/h, respectively. Parametric studies showed that increasing the current density will increase the net electrical power, heating capacity of HRSG and HR heat exchanger, cooling capacity and total irreversibility. Also, with increasing of the current density, both the exergy efficiency and SUCP decrease.
M. Abdollahi Haghghi, S.m. Pesteei , A. Chitsaz Khoyi,
Volume 19, Issue 2 (February 2019)
Abstract
In this paper, a study from the perspective of exergy and cost in the framework of exergoeconomic analysis of a heating and power generation system with parabolic trough solar collectors was carried out as a case study to be used at the engineering faculty of Urmia University. The system consists of a solar subsystem with an Organic Rankine Cycle (ORC). This study is based on three different solar radiation modes during a day, including solar mode, solar and storage mode, and storage mode. In the first mode, the solar flux is at a low level and there is no energy storage. In the second mode, there is energy storage in addition to running the ORC by collectors. In the third mode, only storage tank is used. Paying attention to the actual energy demand of the location and the analysis according to the variable solar radiation are the important points of this study. Due to the weather conditions prevailing on the building, its heating load is 1253.2kW. Also, the electric power required is about 1500kW. Exergoeconomic analysis is based on three important design parameters, including the number of the day through the year, ORC pump input temperature, and ORC turbine inlet pressure examined. The results indicate that in a cold day, the cost per unit of exergy in the three mentioned modes are about 19$/GJ, 16$/GJ, and 20$/GJ, respectively. Also, the highest exergy destruction rate occurs in parabolic trough solar collectors and ORC evaporators.
M. Salehi, A.h. Kakaee, Iman Chitsaz,
Volume 19, Issue 10 (October 2019)
Abstract
Natural gas characteristics make it an attractive choice for replacing with oil fuels which causes climatic problems and environmental pollutions in the world. Generally, using natural gas in an internal combustion engine leads to lower volumetric efficiency of the engine, but gas direct injection technology would improve volumetric efficiency. Furthermore, more research is essential for improving the effectiveness of direct injection engines. A partially stratified charge is an appropriate idea for combustion efficiency improvement in direct injection engines. In the present study, a port injection engine is converted to direct injection engine and feasibility and condition of partially stratified mixture formation are investigated. Also, its effects on combustion and efficiency of the engine, with regards to location and injection timing of injector are noticed. Numerically simulation of current study shows that the formation of partially stratified charge, because of using air-guided method and located injector between air intake valves, is so hard and inaccessible. The high momentum of CNG jet makes a rapid motion of injected gas fuel and is not able to perform an appropriate mixture of air and fuel. Accordingly, an increase in air and fuel ratio is locally seen in the combustion chamber as this causes a drop in combustion efficiency. Although the increase in flame propagation and heat release can be expressed as results of this study, however, the benefits of rapid burning of CNG combustion due to the problems that are mentioned are not so impressive.
Volume 31, Issue 3 (Fall 2025)
Abstract
This article was conducted to investigate the effect of population aging on social, cultural and economic structure in the future of Tehran. Materials and research methods were qualitative studies based on Delphi method. In this study, eleven experts in the field of aging were identified by snowball method, interviewed and by expressing their experiences, the effective components of the phenomenon of aging on social, cultural and economic structures were identified. The research tool was a questionnaire the data of which was used by Delphi in SPSS and Excel software to classify statistical cases and general consensus and reliability during three periods. The results showed that the aging of Iranian society in the coming decades will cause the inability of the government to meet the various needs of the elderly, reduced labor and loneliness and depression. According to the results of the present study and previous research, many factors of the phenomenon of aging affect the three structures of research (social, cultural, economic): economic problems, lack of active manpower, generation gap, decline and gap in the culture of respect and sanctity of elders in the family, extinction and changing the structure of the family, among others. By recognizing these factors, the optimal use of desirable factors and controlling the factors that have the destructive effects of aging on the structures of society, the realization and achievement of a desirable future of society and especially the elderly will be faster.
