Husam Jasim Farhood; Alaa Liaq Hashem
Abstract
In this study, old scrap tire powder was used with building materials commonly used in Iraq, where it was used in some brick holes in the form of powder 0-1 mm, and in this case, it was called scrap tire powder in bricks [ STP-I]. It was compared with the traditional wall that does not contain scrap ...
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In this study, old scrap tire powder was used with building materials commonly used in Iraq, where it was used in some brick holes in the form of powder 0-1 mm, and in this case, it was called scrap tire powder in bricks [ STP-I]. It was compared with the traditional wall that does not contain scrap tires [ STs], which we called No STs. The comparison was by placing a heating source for 8 hours on each wall separately after building it inside a test room prepared for this purpose and by measuring the temperatures on the inner and outer surface and the center of the wall, as well as comparing the thermal resistance and the heat transferred, where we note that the addition of this material may be Reducing the internal surface temperature by 2.56℃, which is a good incentive for this material's role as a thermal insulator.
Faaiza Hassan Al-Naqeeb; Haitham Al-Thairy
Abstract
This paper presents an experimental investigation of the behavior of six reinforced concrete columns under elevated temperatures. A lightweight expanded clay aggregate (LECA) was used in three reinforced concrete columns, in the remaining three columns natural aggregate was used. All reinforced concrete ...
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This paper presents an experimental investigation of the behavior of six reinforced concrete columns under elevated temperatures. A lightweight expanded clay aggregate (LECA) was used in three reinforced concrete columns, in the remaining three columns natural aggregate was used. All reinforced concrete (RC) columns have similar square cross-sectional dimensions of 150mm×150 mm and 1250mm total length. The columns were designed according to ACI Committee 318-2014 and exposed to different elevated temperatures of 400 ºC and 500 ºC. After exposure to elevated temperature, the columns were axially loaded by compression force using an eccentricity ratio (e/h) equal to 0.5. The experimental results demonstrated a remarkable decrease in the ultimate carrying capacity of the columns when subjected to elevated temperature. The experimental test results have also revealed that the lightweight reinforced concrete columns have more fire resistance than the normal-weight reinforced concrete columns under the same elevated temperature. The ultimate load capacity of lightweight reinforced concrete (LWRC) columns decreases by about 6.5 % and 14.3 %, at elevated temperatures of 400 ºC and 500 ºC respectively, compared with the control column at ambient temperature. However, the ultimate load capacity of normal-weight reinforced concrete (NWRC) columns decreases by about 14.15 % and 28.6 %, at elevated temperatures of 400 ºC and 500 ºC, respectively, compared with the control column at ambient temperature. This reduction in the load resistance of the columns might be due to degradations in all properties of concrete and reinforcing steel bars when exposed to high temperatures. In addition, one of the possible reasons for the reduction in the load resistance may be due to a decrease in bond strength between concrete and steel, when subjected to heat.
Mohammed Sadeq Kadhim; Dhafer A. Hamza
Abstract
This study used a NACA 6409 smooth wing section. Its performance is compared to an enhanced design incorporating a revolving cylinder on the upper airfoil surface. The boundary conditions for the present work were Reynolds (105), and the attack angles were (0,2,4,6,8,10,12,14,16). A turbulence model ...
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This study used a NACA 6409 smooth wing section. Its performance is compared to an enhanced design incorporating a revolving cylinder on the upper airfoil surface. The boundary conditions for the present work were Reynolds (105), and the attack angles were (0,2,4,6,8,10,12,14,16). A turbulence model was developed (SST K-), one of the aerodynamics models. This model is well-suited for sensing flow near a wall. The cylinder was evaluated at three positions (25,50,75) percent of the chord's length. The results indicated that position (25 percent C) was optimal, as it resulted in a 24.45 percent increase in lift coefficient at the angle of attack (12). And when the results were compared to those of other studies, they revealed a significant agreement.
Haneen Mohammed Sadiq; Naseer Hameed Hamza
Abstract
In this study, numerical computations of the influence of adding ribs in a rectangular channel on the forced convection heat transfer and laminar fluid flow characteristics has been carried out. The analysis was carried out by using the finite element method to solve the dimensionless governing equations ...
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In this study, numerical computations of the influence of adding ribs in a rectangular channel on the forced convection heat transfer and laminar fluid flow characteristics has been carried out. The analysis was carried out by using the finite element method to solve the dimensionless governing equations for two-dimensional channel with 80 mm height and 2000 mm length at the Reynolds number of (10, 100, and 500), rib height e=8mm with different aspect ratios (AR =2.5, 3.125, 3.75, 4.375, and 5). Also, the study compared two cases of investigations with and without nanofluid (Water/ TiO2) at the volume fractions of nanoparticles of 0, 2 and 4%. The results concluded that, for a certain arrangements, the use of extended surfaces within a rectangular channel can significantly enhance the rate of heat transfer and when the aspect ratios decreases, the Nusselt number increased. However, the existence of ribs within channel in case of constant heat flux can cause a significant improvement of heat transfer compared to that in the corresponding channel under the variable heat flux.
Duaa Yaseen Haran; Ahmed Abed AL-Kadhem Majhool
Abstract
This paper is addressing of a coupling Large-eddy simulation (LES) and RANS turbulence models with mixture fraction/probability density function as a combustion model. The two models have been implemented to simulate ethanol-air spray combustion. The gas phase is described with the Eulerian approach ...
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This paper is addressing of a coupling Large-eddy simulation (LES) and RANS turbulence models with mixture fraction/probability density function as a combustion model. The two models have been implemented to simulate ethanol-air spray combustion. The gas phase is described with the Eulerian approach while the liquid phase is designed using a Lagrangian framework. The LES/PDF approach is obtained statistically. The sub-grid scale energy equation is used with the LES/PDF approach. The numerical results are validated with experimental data. Both LES/PDF and RANS/PDF approaches are compared with the experimental data. The LES/PDF approach shows a good agreement in predicting the average gas temperature compared with RANS/PDF approach. The LES/PDF shows a better prediction of both turbulence intensity profiles and the vortices which are generated in the turbulent flow in comparison with the RANS/PDF approach.
Haider Sahib Al-Mumen
Abstract
Since the Flexible field effect transistor (F-FET) is the building block of any sophisticated electronic circuit, particularly in the area of wearable electronics and biomedical sensors, it has drawn a lot of attention recently. It is usually fabricated using stretchable semiconductors over polymeric ...
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Since the Flexible field effect transistor (F-FET) is the building block of any sophisticated electronic circuit, particularly in the area of wearable electronics and biomedical sensors, it has drawn a lot of attention recently. It is usually fabricated using stretchable semiconductors over polymeric substrates. This paper displays a brief overview of the current fabrication techniques of the F-FET, specifically in terms of the type of substrates and nano semiconductor technologies. As for the applications, flexible devices such as graphene, carbon nanotubes, and nanoparticles seem to be a candidate for future flexible devices due to their excitant electronic and stretchable characteristics.
Maryam S. Awad; Muhaned Shallal
Abstract
In this article, a prototype empirical section of the composite girder was performed to verify the temperature distributions and the changes in concrete bridges under environmental thermal stresses. T-Beam composite section was placed directly subjected to environmental conditions to endure the change ...
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In this article, a prototype empirical section of the composite girder was performed to verify the temperature distributions and the changes in concrete bridges under environmental thermal stresses. T-Beam composite section was placed directly subjected to environmental conditions to endure the change in convection, the convection includes solar radiation, surrounding air temperature, and wind speed. In addition, this paper includes the 3D finite-element thermal studies represented by the COMSOL MULTIPHYSIC program, with particular reference to the influence of several parametric studies that are represented by changes in concrete thickness, adding asphalt layer, and finally change the value of wind speed. The section is prepared with fifteen thermocouples in different places in steel and concrete in the actual and theoretical models to evaluate the temperature distribution inside the composite bridges and their effects in the selected points. COMSOL MULTIPHYSIC showed a good ability to simulate convection, heat conduction, and radiation within the surrounding environment. Such as the thermocouple (TC3) the minimum temperature was 33.18 oC, 33.29 oC, the maximum temperature was 63.67 oC, and 62.77 oC for experimental and theoretical results respectively while the maximum and minimum difference between experimental and FE temperatures is 2.96 and 0.099 for TC3 respectively. Therefore, it can be said that all the thermocouples results showed a good agreement between practical and theoretical results.
Riham Ghanim Najeeb; Ali H Abbar
Abstract
The present study focused on the treatment of hospital wastewater generated from Al-Diwaniya Hospital located at Al-Diwaniya City/ southern Iraq via an Electrocoagulation (EC) process with SS/Fe electrodes. Response Surface Methodology (RSM) was used to evaluate the main effects of parameters, ...
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The present study focused on the treatment of hospital wastewater generated from Al-Diwaniya Hospital located at Al-Diwaniya City/ southern Iraq via an Electrocoagulation (EC) process with SS/Fe electrodes. Response Surface Methodology (RSM) was used to evaluate the main effects of parameters, their simultaneous interactions, and the quadratic effect to achieve the optimum condition for the EC process. Chemical Oxygen Demand (COD) was observed and measured for each experiment as it can be used as a good indicator of the quality of wastewater. The impacts of three factors such as current density (5-25mA/cm2), pH (4-10), and addition of NaCl(0-3g/l) were evaluated. The obtained experimental data were fitted to a second-order polynomial equation with analysis by variance analysis (ANOVA). The results show that current density has a major impact on the efficiency of COD removal followed by the addition of NaCl while pH has a lower effect on the COD removal under the studied range of pH. ANOVA results showed that the determination coefficient of the models was R2 98.18% confirming that the quadratic model was significant with a good fitting between the experimental and predicted results. The optimized operating parameters were a current density of 25 mA/cm2, pH of 7.8, and NaCl addition of 3 g/l in which COD removal efficiency of 97.14% was achieved with a specific energy consumption of (30.914) kWh/kgCOD.
Zainab Ali Talib; Jalal Taqi AL-Obeadi
Abstract
Traffic simulation models play a major role in allowing traffic engineers to assess complex traffic situations such as U-turn section. Such models help in proposing solutions and proposing alternative scenarios without committing too many expensive resources and this models are necessary to implement ...
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Traffic simulation models play a major role in allowing traffic engineers to assess complex traffic situations such as U-turn section. Such models help in proposing solutions and proposing alternative scenarios without committing too many expensive resources and this models are necessary to implement alternative strategies in the field. Simulation traffic models can significantly improve the quality of road network planning and design in urban areas. According to filed observation, the U-turn movement cause traffic congestion at both origin and distention (opposite) roads. This study introduces many alternatives to enhance the movement at U-turn section. These alternatives have been tested by using simulation models. The PTV VISSIM software is used to development the models. This development model has been calibrated and validated by using filed data collected from Al-Diwaniyah city, Iraq.
