Journal of Engineering

A progressive increase in the desire for environmentally friendly lubricants by users and strict government regulations for the use of these lubricants has provided an opportunity to use plant oils as biodegradable lubricants, therefore vegetable oils have been investigated to replace oil lubricants because of their maintaining the conditions of nature (environment) properties. In this paper, the influences of the blending ratio of mustard seeds oil with commercial mineral oil (SAE40) on the tribological characteristics were investigated and compared with mineral oil using the four-ball tribotester. Mustard seeds oil was blended with mineral oil at a volumetric ratio ranging from 22.5 to 90%. All experimental works were confirmed to ASTM D4172-B standard. The results exhibit that some blends of mustard seeds oil with mineral oil have lower wear scar diameter, friction torque, Friction coefficient and a higher parameter of flash temperature value compared to mineral oil and neat mustard seed oil. In conclusion, the mustard seed oil blend (MU22.5) shows a better anti-wear and anti-friction performance compared to oil samples. Therefore, mustard seeds oil has the potential to be used as a lubricant of mating surfaces.

The present work evaluated the differences in mechanical properties of two athletic prosthetic feet samples when subjected to impact while running. Two feet samples designated as design A and B were manufactured using layers of different orientations of woven glass fiber reinforced with unsaturated polyester resin as bonding epoxy. The samples’ layers were fabricated with hand lay-up method. A theoretical study was carried out to calculate the mechanical properties of the composite material used in feet manufacturing, then experimental load-deflection test was applied at 0 degree position and 25 degree dorsiflexion feet position and impact test were applied for both feet designs to observe the behavior of the feet under static and impact loading and compare properties like stiffness, efficiency, rigidity, and shock absorption at different drop angles range from 25 degrees to 60 degrees which perform the foot positions while running. The load-deflection test result shows that the maximum deflection of the proposed design B was 32.2 mm at 0° and 38.45mm at 25°. While it was 41mm at 0˚ and 39mm at 25˚ for design A. Impact test result shows that design B foot gives peak load of 128 .7 kg with a peak time of 0.06 sec, while design Afoot gives 125.32 kg peak load with a time of 0.069 sec.

Solar collectors, in general, are utilized to convert the solar energy into heat energy, where it is employed to generate electricity. The non-concentrating solar collector with a circular shape was adopted in the present study. Ambient air is heated under a translucent roof where buoyant air is drawn from outside periphery towards the collector center (tower base). The present study is aimed to predict and visualize the thermal-hydrodynamic behavior for airflow under inclined roof of the solar air collector, SAC. Three-dimensional of the SAC model using the re-normalization group, RNG, k−ε turbulence viscus model is simulated. The simulation was carried out by using ANSYS-FLUENT 14.5. The simulation results demonstrated that at same insolation; airflow, ground and air temperatures increase when the collector radius decreases towards the collector center. The ground temperature and air velocity increase, while airflow temperature decreases when the inclination angle increases from 0° to 20° due to changing in airflow movement. More decreasing in airflow temperature has been occurred when the inlet height increases from 0.1m to 0.25m. The simulation results were validated by comparing with the experimental data. In conclusions, the obtained results showed the capability of producing warm airflow to generate electricity in Baghdad city.

Twisted tape insertion in the smooth plain tube is one of the types of passive methods that are used to enhance heat transfer. Swirl fluid flow inside the tube and related heat transfer characteristics are very complex. ANSYS FLUENT (V 16.1) and ASPEN industrial program are used in analyzing this technique for enhancement heat transfer. A circular plain tube has length L=8534mm and 17 mm inner diameter with a twisted tape of twist ratio of y = (H/D) = (150/17) =8.8 along the plain tube were considered for this study. Eight Reynolds numbers (Re) of 784, 1000, 2000, 3000, 4000, 5000, 6000 and 7000 are used to analyze the response of thermal performance. Crude oil API 28 exit temperature, film heat transfer coefficient, Nusselt number and overall enhancement ratio results are presented for both empty and inserted plain tube with a comparison between the two cases. An increase of 0.76 to 2.36 overall enhancement is predicted with twist ratio 8.8 for Reynolds number 784 to 7000 respectively.

There are many methods for estimating permeability. In this paper, permeability has been estimated by two methods: the conventional and modified methods used to calculate the flow zone indicator (FZI). The hydraulic flow unit (HU) was identified by the FZI technique, which is effective in predicting permeability in un-cored intervals/wells. HU is related to FZI and rock quality index (RQI). All available cores from 7 wells (Su-4, Su-5, Su-7, Su-8, Su-9, Su-12, and Su-14) were used as a database for HU classification. The plot of probability cumulative of FZI is used. The plot of core-derived probability FZI for both modified and conventional methods indicates 4 HUs (A, B, C, and D) for the Nahr Umr formation based on the four straight lines. The permeability was calculated by two methods for comparison and choosing the best. The modified FZI method gives better results because the predicted permeability by this method demonstrates a coefficient of correlation (R² = 0.9645) higher than that of the conventional approach (R² = 0.892). When plotting RQI versus ∅_z on a log-log scale, all core samples with similar FZI values will lie on a straight line with a unit slope. Other core samples that have different FZI values will lie on other parallel lines. All lines in the (RQI and ∅_z) plot of the modified FZI method have a unit slope and are more parallel than those of the conventional approach. The plot of probability cumulative of FZIm is used to determine the number of hydraulic flow units for the Nahr Umr formation. The plot of core-derived probability FZI for both modified and conventional methods indicates 4 HUs for the Nahr Umr formation based on the four straight lines. These four straight lines of the modified FZI method were more distinguished than those of the conventional approach.

This study investigated the feasibility of anaerobic co-digestion of giant reed (GR) inoculated with waste manure as a co-substrate for biogas production. The performance of co-digestion was evaluated in 4 anaerobic digesters operated in batch mode at different conditions. The effects of alkali pretreatment with NaOH (4% w/v) solution, inoculum type, and thermal condition were studied. The results demonstrated that the alkali-pretreatment of GR enhanced the biogas generation by about 15% at mesophilic conditions. Thermophilic conditions enhanced the biogas recovery from both alkali-free and alkali pretreated GR by 15% and 127%, respectively. The kinetic study of the co-digestion process of GR for biogas recovery suggested a significant agreement between measured and predicted values obtained by Modified Gompertz Model with correlation coefficients ≥ 0.98 indicating favorable conditions for the co-digestion of inoculated GR.

To damp the low-frequency oscillations which occurred due to the disturbances in the electrical power system, the generators are equipped with Power System Stabilizer (PSS) that provide supplementary feedback stabilizing signals. The low-frequency oscillations in power system are classified as local mode oscillations, intra-area mode oscillation, and interarea mode oscillations. A suitable PSS model was selected considering the low frequencies oscillation in the inter-area mode based on conventional PSS and Fuzzy Logic Controller. Two types of (FIS) Mamdani and Sugeno were considered in this paper. The software of the methods was executed using MATLAB R2015a package.

The management of construction projects needs to complete the basics of system management and work. Starting from the idea and how to turn it into a full study and ending at the construction project completion arriving at the purpose prepared for it, so the projects need to control its operation and integration system in order to succeed. It is no secret for those concerned in construction projects field that the design stage is a very important stage in construction project because it determines the final features of the project through the requirements provided by the employer for the consultant to formulate it during this phase in the form of plans, drawings, and specifications, then translated on the ground as the shape of completed project meets those requirements. Therefore, it has been necessary to focus in this paper on the design stage also demonstrated and analyzed the most important risks facing this stage and their impact on a construction project by introducing a questionnaire to identify the most important risk factors at this stage affecting the project. The paper showed that the effect of the design stage on Lump sum type of project contract was higher than the unit price, while the most important factor affecting a project is the fast response of the design team to prepare the design documents in order to facilitate the workflow and sequence of execution with an effect level of 3.714.

This study focuses on the slab-beam interaction in one-way systems. In the context of this study, slab-beam interaction means how beam deflection can affect moment distribution in one-way slabs. This interaction is usually neglected in the traditional approximate analysis that is adopted in engineering practice and design codes. Slab positive moments have been considered as indicators on the accuracy of approximate methods, as they overestimate negative moments while underestimating positive moments. After proposing of effecting parameters in slab-beam interaction including of panel length and width, beam dimensions, and slab thickness, Buckingham’s theorem has been adopted to transform the dimensional-model into a non-dimensional qualitative one. Different case studies with finite element models have been adopted to generate points on the proposed qualitative non-dimensional model. Finally, linear regression analyses have been adopted to develop the corresponding quantitative models. Case studies and corresponding regression analysis indicate that non-dimensional parameters adopted in the model are related linearly with a correlation coefficient in the range of 0.97 and that an error up to 250% may be noted due to neglecting the slab-beam interaction. Therefore, a condition related to the relative stiffness of supporting beams should be added to the current conditions for the approximated methods to be more accurate and more compatible with those adopted in the analysis of two-way systems.

This paper deals with finite element modeling of the ultimate load behavior of double skin composite (DSC) slabs. In a DSC slab, shear connectors in the form of nut bolt technique studs are used to transfer shear between the outer skin made of steel plates and the concrete core. The current study is based on finite element analysis using ANSYS Version 11 APDL release computer program. Experimental programmes were carried out by the others, two simply supported DSC beams were tested until failure under a concentrated load applied at the center. These test specimens were analyzed by the finite element method and the analyses have shown that these slabs displayed a high degree of flexural characteristics, ultimate strength, and ductility. The close agreement has been observed between the finite element and experimental results for ultimate loads and load–deflection responses. The finite element model was thus found to be capable of predicting the behavior of DSC slabs accurately.

Sustainable crop production in a coarse soil texture is challenging due to high water permeability and low soil water holding capacity. In this paper, subsurface water retention technology (SWRT) through impermeable polyethylene membranes was placed at depth 35 cm below ground surface and within the root zone to evaluate and compare the impact of these membranes and control treatment (without using the membranes) on yield and water use efficiency of eggplant inside the greenhouse. The study was conducted in Al-Fahamah Township, Baghdad, Iraq during spring growing season 2017. Results demonstrated the yield and water use efficiencies were 3.483 kg/m² and 5.653 kg/m³, respectively for SWRT treatment plot and 3.286 kg/m² and 3.709 kg/m³, respectively for treatment without using SWRT. The increasing percentages for yield and water use efficiency were 6% and 52%, respectively. Additionally, saving in irrigation water in the SWRT membrane was about 44% of the total applied depth comparing with the control treatment.

This paper deals with finite element modeling of the ultimate load behavior of double skin composite (DSC) slabs. In a DSC slab, shear connectors in the form of nut bolt technique studs are used to transfer shear between the outer skin made of steel plates and the concrete core. The current study is based on finite element analysis using ANSYS Version 11 APDL release computer program. Experimental programmes were carried out by the others, two simply supported DSC beams were tested until failure under a concentrated load applied at the center. These test specimens were analyzed by the finite element method and the analyses have shown that these slabs displayed a high degree of flexural characteristics, ultimate strength, and ductility. The close agreement has been observed between the finite element and experimental results for ultimate loads and load–deflection responses. The finite element model was thus found to be capable of predicting the behavior of DSC slabs accurately.