فهرست مطالب بهروز راعی

 The present study investigates the ability to improve the stability and heat transfer performance of water coolant fluid by dispersing aluminum oxide nanoparticles in water. Surfactant-free nanofluid with 4 different volume fractions of 0.05%, 0.5%, 1% and 2% were prepared by two-step method. The stability of the nanofluid was monitored by continuous imaging (visualization) and dynamic light scattering (DLS) techniques. Thermal conductivity, viscosity and density of aluminum oxide-water nanofluid were measured in 4 concentrations and at temperatures of 25, 35 and 45 °C. The results showed that the thermal conductivity and viscosity of aluminum oxide-water nanofluid increases with rising concentration. The viscosity of nanofluids in all concentrations were higher than the base fluid. This is while the increase in viscosity was almost independent of the increase in temperature. The highest percentage increase in the thermal conductivity of nanofluid is equal 49%, which was obtained at a concentration of 2% and a temperature of 45 °C. New correlations with high precision were presented based on the experimental data of thermal conductivity and viscosity of nanofluids. The heat transfer performance and pumping power of nanofluid were analyzed based on several performance criteria. The advantageous results of increasing the heat transfer capability made aluminum oxide-water nanofluid a potential candidate for cooling fluid in practical applications.

The pH level of nanofluids plays an important role in stability and thermal conductivity. However limited studies have been done in this field. In this research, the effect of pH on the stability and thermal conductivity of ZnO-EG nanofluid at concentrations of 0.05 and 0.75% volumetric fraction and MgO-W at concentrations of 0.05 and 0.5% volumetric fraction were investigated. Experimental measurements of the thermal conductivity were performed by a thermal properties analyzer device at a constant temperature of 25 °C. The results showed that the pH strongly affected the stability of nanofluids so that at the pH of the isoelectric point (IEP), complete aggregation and sedimentation were observed. The thermal conductivity of nanofluids has the lowest value at the pH of the isoelectric point, but as the pH moves away from the isoelectric point, the thermal conductivity  increases. The highest enhancement in the thermal conductivity of ZnO-EG nanofluid was 63%, which was obtained at a volume fraction of 0.75% and pH = 12. However, the highest enhancement in the thermal conductivity of MgO-W nanofluid was 49%, which was obtained at a volume fraction of 0.5% and pH = 12. Finally, using the experimental results and with the help of curve fitting, equations with good quality were presented to predict the effective thermal conductivity of metal oxide nanofluids.

 The main aim is to present a comprehensive model of e-governance maturity, which includes all areas of governmental interactions with other sectors. Identifying the evaluation components of maturity model, leveling e- governance and explaining the measures under each level and component are the other objectives.

Design/Methodology/Approach:

 The methodology is designed based on the optimization of conventional approaches with three main stages, which includes studying e-government and e-governance maturity models, comparing existing models and extracting new subcomponents, providing a new structure for evaluating e-governance maturity, with the help of expert opinions, usage of questionnaire tools and confirmatory factor analysis to confirm the proposed model and define different levels of maturity and measures appropriate to the components of maturity.

 Based on literature review and expert opinions, 27 sub-components were extracted, which were classified into six components, including management, strategy, technology, security, people, and evaluation and measurement. Factor analysis and questionnaire data confirmed the model structure. Four levels have been proposed for the e-governance maturity model: awareness, purposeful managed endeavor, and optimal ecosystem.

Limitations & Consequences: 

Accessing to the actions of governmental affairs in the development of e-governance and the impossibility of examining the feasibility of the proposed model is one of the most important limitations of the research.

Practical Consequences: 

The proposed maturity model is a guide for the excellence of the executive organs of the country in the implementation of e-government and its levels show the path of their growth and is the basis for coordination between different organs.

Innovation or value of the Article: 

Identifying the most important components and subcomponents of e-governance maturity assessment in accordance with the characteristics of the present age and presenting it in the form of an appropriate structure along with a description of measures by levels and subcomponents of the model.

Accurate determination of the thermophysical properties of nanofluids and the parameters affecting them are of particular importance in the industrialization of nanofluids. One of the most important parameters affecting properties such as viscosity and thermal conductivity is the pH of the nanofluid. In this research, the pH levels of three metal oxide nanoparticles including aluminum oxide (AL2O3), magnesium oxide (MgO) and zinc oxide (ZnO) dispersed in distilled water were measured in the temperature range between 303 K to 333 K and concentration range between 0.01 to 1% volumetric concentration. For more accuracy, pH measurements were performed twice for each sample and the mean value for the final pH was recorded. The results showed that with increasing the temperature by about 10%, the pH values ​​of aluminum oxide, magnesium oxide and zinc oxide nanofluids decreased by 37, 11 and 9%, respectively. Also, the addition of aluminum oxide nanoparticles has given acidic properties to distilled water, but the addition of magnesium oxide and zinc oxide nanoparticles to distilled water have given alkaline properties to the suspension. Finally, using the experimental results obtained for three metal oxide nanofluids, an equation for predicting pH as a function of concentration and temperature was proposed.

Along with the development of information and communication technology in all areas, information technology in the management and administration of countries has also developed and concepts such as e-government and e-governance have emerged. Although e-government emphasizes providing services to stakeholders by internet, e-governance emphasizes the need to change the way the government communicates democratically with its citizens. Identifying the components of e-government evaluation In addition to identifying the important aspects for the development of e-government in the executive apparatus, it is a tool to know the status of progress of the executive apparatus and identify strengths and areas for improvement in the development of e-government. The main purpose of this study is to study the criteria and identify the components of evaluating the progress of government executive bodies in the development of e-government under the title of e-government evaluation framework. Accordingly, the initial criteria have been identified based on a literature study. Then, with the help of expert opinions, the criteria are reviewed and defined. With the help of a questionnaire, the importance of each criterion in the development of e-government in the country's executive apparatus has been questioned through random sampling. After measuring the importance of the criteria from the perspective of experts, effective criteria have been categorized using exploratory factor analysis. The results of factor analysis show 27 criteria identified in six components; e-governance quality, e-governance leadership and motivation, productivity and facilitation, support, e-services management, and e-legislation are summarized. Another output of this study is the coefficient of the importance of each of the criteria in measuring the identified factor.