University of Thi-Qar Journal for Engineering Sciences

In structural engineering, introducing an efficient structural elements with high ratio of strength or ductility to weight is a challenge.This paper is presenting and developing aluminum columns having circular hollow section strengthened with CFRP possess the highest specific (divided -by weight) mechanical properties to be advantageous in lightweight and space limited structures .The structural performance of these columns was investigated experimentally by using different strengthening orient styles and CFRP piling layers. The column specimens were subjected to uniform axial compression. The strength, ductility, axial load-shortening displacement relationships, lateral strains, and failure modes of columns were presented. Designing guideline empirical equations were derived from experimental results, the predicted unfactored strengths are found to be in a good agreement with the experimental values.

The film cooling effectiveness and local heat transfer coefficient for different hole space ratio have been experimentally investigated on a flat plate in the current study. The investigations were done by using a single test transient IR thermography technique. Three models of staggered holes arrangement are investigated. ). Each model is provided with five columns of holes, these models are arranged with staggered row holes. The holes diameter is 4mm, the longitudinal distance (X/D) is 10, and the span distance between two neighboring holes (S/D) are 3, 5, and 7 respectively. The attitude of the holes is fixed at inclination angle (θ= 30º ). The blowing ratios, cold to hot air flow ratio, have been changed three times (BR= 0.5, 1.0, and 1.5) during the experimental program. The experimental investigation showed that the thermal performance decreases as the space ratio (S/D) increases for all blowing ratios, and the film cooling effectiveness decreases as the blowing ratio increases for all the three models.

In this research,the effect of using different water-cement ratios (w/c = 0.33, 0.35, and 0.4),different aggregate sizes(MAS= 40,20,14,10 and 5.0)mm., adding different ratios of sand (5,10,and 20)%, as well as,compaction on the strength and permeability of pervious concrete were studied. Test results indicated that, the best w/c ratio was 0.33 for MAS=40,20 and 14 mm., while the best w/c ratios were 0.35 and 0.4 for MAS=10 mm. and 5.0 mm. respectively. In this research we considered a control mix (C:A=1:6, w/c =0.35 and MAS=10 mm permeability = 2 sec) as the optimum mix proportions which it was obtained by trial mixes.It was clear that the best sand ratio was (10%). Results also indicated that, when adding 0.5% super-plastizer of cement weight, increase compressive strength. Finally adding sand with super-plastizer increase compressive strength but reduce permeability.

In this paper an Artificial Neural Networks (ANNS) model is designed to predict the Total Dissolved Solids (TDS) concentration in marsh water. A previous data set are selected from previous studies which done on analysis of marsh water quality, these data are arranged in a format of five input parameters to feed forword back-propagation including the acidity (pH), calcium concentration (C), Magnesium Concentration (M) , Chloride Concentration (Cl) and Sulphate Concentration (S), and one output parameter as Total Dissolved Solids concentration. Artificial Neural Network used to study the effect of each parameter on TDS concentration in marsh water. Several structures of ANNs model is examined with different transfer functions, activation functions, number of neurons in each hidden layer and number of hidden layers. Results show that the two hidden layer network with transfer function (trainscg) with (12 & 10) neurons in the first and second hidden layer respectively and (tansig-tansig-purelin) gives the best performance (Mean Square Error: 3.05e-5) network for this prediction.

Laboratory investigations were performed in order to assess the effectiveness of three types of inhibitors, calcium nitrite, ethanolamine and Sika ferro gard 901(commercial inhibitor) with 1%, 2% and 3% concentration by weight of cement for each inhibitor to retarding corrosion of steel embedded in concrete. Concrete specimens were used to assess the effects of corrosion inhibitors on the compressive and tensile strength of concrete and corrosion of reinforcement.Some of the specimens were subjected to wetting and drying cycles and reinforcement corrosion was evaluated by measuring corrosion potentials and corrosion current density. Other concrete specimens were immersed in the salt (Cl-+So3-2) solution and reinforcement corrosion was accelerated by impressing an anodic potential of +12 V from a DC power supply and measuring the time-to-cracking of the concrete specimens.The results indicated that the concrete specimens incorporated corrosion inhibitors of calcium nitrite and Sika ferro gard 901 did not adversely affect the compressive and tensile strength of concrete. Furthermore, the time-to-cracking in specimens contains those two inhibitors (calcium nitrite and Sika ferro gard 901) were higher. Two percent of calcium nitrite followed by three percent of Sika ferro gard 901 were efficient in delaying the initiation of reinforcement corrosion and reducing the rate of reinforcement corrosion current density in the concrete specimens, while all the percentages of ethanolamine corrosion inhibitor were ineffective to delay corrosion of the rebar under the conditions of the study and it's adversely affect the strength.

This paper presents an experimental investigation on the effect of silica fume on the mechanical properties of concrete obtained by replacing 50% of weight of stone aggregate by crushed clay-brick. The only variable considered in this study was the dosage of silica which it is a percent of cement weight, the percent values of replacement silica fume are (0%, 2%, 4%, 6%, and 8%) of cement weight. The comparative study is focus on the effect of the silica fume on this type of concrete not the effect of replacement of crushed brick. The added silica fume has active effect on the strength of crushed brick concrete. The effect of using silica fume on compressive strength is different for the different replacement of silica fume and it is more active for the 2% replacement at 7 days age, while the replacement that yield best enhancement at 28 days is 4%. The compressive strength for 28 days age is about 27.5 MPa,29.5 MPa, 38.5 MPa,31.4MPa, and 10MPa,for (0%, 2%,4%,6%, and8%) of replacement silica percent .Further more the best increasing in tensile strength is at 2%while there is a small gradually increasing in gain in modulus of rupture with using silica fume until 6%, which beyond the least value it starts to drop.The high level which is observed in this study beyond 6% reduces the gain in strength of compressive at 28 days and it gets a compressive strength less than the control value at 7 days. Furthermore it gets a reduction in tensile strength and modulus of rupture in at 28days.

The cyclostationary based spectrum sensing algorithm is especially suitable for detection of orthogonal frequency division multiplexing (OFDM) signals that exhibit strong periodic correlation due to insertion of cyclic prefix between OFDM blocks.Normally, the cyclic prefix is used to remove the Intersymbol interference (ISI) and intercarrier interference (ICI) of the OFDM signal and so it eliminates a need for complex equalizer. In this paper, simulation results demonstrate the normalized spectrum correlation function of the primary OFDM signal used in cognitive radio systems with different values of cyclic frequency. Two techniques are assumed to be used as PAPR reduction of OFDM transmitted signal. The results show that only one of them has no apparent effect on the correlation performance of the cyclostationary detector. Finally, it is found that a reduction of 30% in the implementation complexity can be taken by suitable choice of detector cyclic frequency.

A simply supported beam is used to calculate the critical buckling load. A common beam sections with constant cross sectional area are used to analyze the results using ANSYS11 program which gives a good results as comparing with the theoretical equation. The critical buckling load depends on the shape and dimensions of beam section which has constant cross sectional area. It observed that the critical buckling load is higher with a wide range of width for thinner hollow rectangular-section than the thicker section and lower for ( I, T & L-sections). Changing the width or thickness for U & Z-sections gave a small effect on the critical buckling load. Increasing the thickness of hollow circle beam section gives a decreasing in the critical buckling load. The last beam section gives a higher critical buckling load as comparing with solid circle section of the same cross sectional area. The same phenomenon is found for hollow rectangular-section as comparing with the solid section.

Integrated advanced wastewater treatment provides important fundamental solutions to problems associated with water scarcity prevailing in arid and semi-arid climatic regions.This was accomplished through treated water with specific specification and characteristics suitable to be used for agricultural, domestic, and industrial purposes. This study is concerned with the use of genetic algorithm procedure for the optimum design of integrated advance wastewater treatment units, with their various types and characteristics. The aim of optimum wastewater treatment units design is to attain optimum values of certain pre-defined objective function. The objective function is to satisfy certain constraints and achieve minimum capital, maintenance, and operation costs.Chemical clarification treatment unit was used in this study.This study includes development of computer program for advances wastewater treatment plants design adopting genetic algorithm. The program was developed using Matlab software. The results obtained from this study include the finding of optimum design criteria for advanced wastewater treatment plants. The obtained design criteria are satisfying the required water quality with minimum treatment cost.