Al-Khwarizmi Engineering Journal

The present study investigates the effect of acetic acid on corrosion behavior and its potential of hydrothermally sealed anodized AA2319-Al-alloys. Anodizing treatment was performed in stagnant phosphoric acid electrolyte with or without addition of acetic acid. Hydrothermal sealing was carried out in boiling water for each anodized specimen. The open circuit potential of the unsealed and sealed anodized samples was examined using open circuit potential measurement for the purpose of starting in scanning polarization diagrams. The potentiostatic polarization technique measurements were performed to assess corrosion behavior and sealing quality (i.e., degree of sealing) of the unsealed and sealed anodized aluminum. It was shown that the potentiostatic anodic and cathodic polarization of anodized aluminum was sensitive to degree of seal, which was more efficient in the case of anodized aluminum formed in acetic-phosphoric acid electrolyte mainly due to their higher corrosion potential and lower corrosion current, generally passes lower anodic and cathodic currents obtained at sealing exposure time 60 min. This suggests a specific role of the species on the sealed anodized aluminum surface coating, which contributes to the increasing of the performance in terms of corrosion improvement. The present study clearly validates the beneficial role of acetic acid in phosphoric acid anodizing baths for the corrosion protection of AA2319-Al-alloys.

Nano-crystalline ZSM-5 zeolite was synthesized by hydrothermal method using chelating agent and two gel compositions:Compositionɪ:Al2O3:86SiO2:5.5TPA:12.7Na2O:3.4Trien:3320H2O.Compositionɪɪ:Al2O3:68SiO2:5.4TPA:10Na2O:2.6Trien:2626H2O.Study of hydrothermal reaction factors on characteristics of nano- sized zsm-5 has been carried on ,among them are crystallization temperature, crystallization time and concentration of template ( TPAOH ) solution. Synthesis was accomplished in PTFE lined autoclave ( reactor ) . The product were characterized by X-ray diffraction ( XRD ),Atomic force microscopy ( AFM ),scanning electron microscopy, Fourier transform infrared ( FTIR ) and Brunauer-Emmet-Teller (N2 absorption-desorption isotherm).SEM and XRD results indicate that crystallinity of synthesized zeolite increase with increasing crystallization time and temperature. AFM results indicate that a nano-sized level of about 50nm was reached for "particle average diameter". FTIR results showed that the required peaks near "1080,800,550,450 cm-1" have been clearly obtained, Furthermore the results showed strong effect of template (TPAOH) solution concentration on crystallinity and decreasing of particle size towards nano-size level.

In order to make an improvement associated with rotating biological contactor (RBC), a new design of biofilm reactor called as Rotating perforated disc biological contactor (RPBC) was developed in which the rotating discs are perforated. The transfer of oxygen from air to wastewater was investigated. Mass-transfer coefficient (KLa) in the liquid phase was determined by measuring the rate transfer of oxygen. A laboratory scale of (RPBC) consisted of a semicircular trough was used with a working capacity of 40 liters capacity of liquid. Synthetic wastewater was used as a liquid phase, while air was used as a gas phase. The effects of many parameters on the liquid phase mass transfer coefficient (KLa) were investigated. These parameters are; the disc rotational speed (N), the pore diameter (d) and clearance between the discs(C). It was found that the value of KLa was increased as the rotation speed (N) increased, and as the diameter of the pores in the disc (d) increased. While the values of (KLa) was decreased continuously with increasing the clearance(C). Suitable correlation was developed for estimating mass transfer coefficient (KLa) in this type of bioreactor.

Electrical magnate was designed and constructed, the optimum Magnetic flux and the effect of time on the physical properties of the alkaline (magnetic water) produced from the bottled drinking water [the total dissolved solids (TDS) or the electrical conductivity, and pH] were studied, to simulate ZamZam water in Mekka Saudi Arabia. Also, the efficiency of magnetic field from this designed electrical magnate in decreasing the TDS of sea water (of 1500 ppm NaCl Content), to convert it to water suitable for irrigation (TDS<1000 ppm) was investigated in this work.The results show that the magnetic flux from our designed electrical magnate in the range of (0.013- 0.08) Tesla and 30 minutes magnetic treatment time is sufficient to produce alkaline water with pH similar to ZamZam water (pH from 7.85- 8). While 60 minutes of magnetic treatment results to higher values of pH and the maximum pH value of 8.9 is obtained when the magnetic flux is 0.026 Tesla. The investigation for reducing the TDS of water having 1500 ppm NaCl show that , the maximum decrease in TDS is took place when the magnetic flux is 0.013 Tesla(coil of 100 turn and 1.5 V) and the time for magnetic treatment is 30 minutes where the TDS of 1730 ppm reduced to 1290 ppm is obtained .The effect of magnetic treatment on the pH change of high NaCl content water give maximum pH value of 8.1 when the magnetic flux is 0.013 and 0.028 Tesla (the voltages is 1.5 & 3 V respectively and 100 turn coil) and the time period of magnetic treatment is 30 minutes. The trend of results agreed well with previous studies, where the magnetic treatment lead always to increase of pH, decrease in TDS and electrical conductivity

This work involves studying the effect of adding some selective organic component mixture on corrosion behavior of pure Al and its alloys in condensed synthetic automotive solution (CSAS) at room temperature. This mixture indicates the increasing of octane number in previous study and in this study show the increasing in corrosion resistance through the decreasing in corrosion rate values. Electrochemical measurements were carried out by potentiostat at 3 mV/sec to estimate the corrosion parameters using Tafel extrapolation method, in addition to cyclic polarization test to know the pitting susceptibility of materials in tested medium.The cathodic Tafel slope (bc) were increased after adding the organic component mixture. But the anodic Tafel slopes (ba) were varied after addition of the mixture. The increase in cathodic slope indicates the presence of a film on the surface of the tested material, which is less permeable and can even obstruct the metal dissolution reaction but still permits an electrochemical reaction to occur. This behavior can be achieved by the electronic density on oxygen and nitrogen atoms in the organic component mixture.

Hexapod robot is a flexible mechanical robot with six legs. It has the ability to walk over terrain. The hexapod robot look likes the insect so it has the same gaits. These gaits are tripod, wave and ripple gaits. Hexapod robot needs to stay statically stable at all the times during each gait in order not to fall with three or more legs continuously contacts with the ground. The safety static stability walking is called (the stability margin). In this paper, the forward and inverse kinematics are derived for each hexapod’s leg in order to simulate the hexapod robot model walking using MATLAB R2010a for all gaits and the geometry in order to derive the equations of the sub-constraint workspaces for each hexapod’s leg. They are defined as the sub-constraint workspaces volumes when the legs are moving without collision with each other and they are useful to keep the legs stable from falling during each gait. A smooth gait was analyzed and enhanced for each hexapod’s leg in two phases, stance phase and swing phase. The proposed work focused on the two approaches first, the modified classical stability margins. In this approach, the range of stability margins is evaluated for all gaits. The second method is called stability margins using Genetic Algorithm (GA) that enhanced the static stability by getting the best stability margins for hexapod robot and these results are useful to get best stable path planning of hexapod robot with smaller error than the first approach and with better new stable coordinates of legs tips than the first method. In addition, the second approach is useful for getting the better new stable center body coordinates than center body coordinates in the first approach of hexapod robot.

One of the most suitable materials to be used in latent heat thermal energy storage system (LHTES) are Phase change materials, but a problem of slow melting and solidification processes made many researchers focusing on how to improve their thermal properties. This experimental work concerned with the enhancing of thermal conductivity of phase change material. The enhancing method was by the addition of copper Lessing rings in phase change material (paraffin wax). The effect of diameter for the used rings was studied by using two different diameters (0.5 cm and 1cm). Also, three volumetric percentages of rings addition (3%, 6% and 10%) were tested for each diameter. The discharging process was done with four velocities for each case. The obtained results indicated that the maximum volumetric percentage gave a diminished time for melting and maximized the heat transfer in both PCM and air sides as compare with the case of no rings, but the effect of these rings had lower effect on the solidification time. In case of 1 cm rings diameter minimum time for melting was obtained for both 3% and 6% volumetric percentages as compared with the same percentages in case of 0.5 cm diameter rings, while the latter with 10% volumetric percentage overcomes the 1 cm diameter rings for the same previous percentage. Also it can be seen that the minimum velocity (v=1m/s) gave the utmost outlet temperature and with the maximum one (v=3m/s), the minimum solidification time achieved.

Lightweight materials is used in the sheet metal hydroforming process, because it can be adapted to the manufacturing of complex structural components into a single body with high structural stiffness. Sheet hydroforming has been successfully developed in industry such as in the manufacturing of the components of automotive.The aim of this study is to simulate the experimental results ( such as the amount of pressure required to hydroforming process, stresses, and strains distribution) with results of finite element analyses (FEA) (ANSYS 11) for aluminum alloy (AA5652) sheets with thickness (1.2mm) before heat treatment (BHT) and after heat treatment (AHT) respectively in the circular die with cavity equals to (20mm) . The comparison of results by these two approaches show the same tendency that an improvement formability, also the plastic deformation is greatly enhanced AHT for same metal.

Experimental work from Magnetic Abrasive Finishing (MAF) tests was carried out design parameters (amplitude, and number of cycle which are formed the shape of electromagnetic pole), and technological parameters (current, cutting speed, working gap, and finishing time) all have an influence on the mechanical properties of the surface layer in MAF process. This research has made to study the effect of design and technological parameters on the surface roughness (Ra), micro hardness (Hv) and material removal (MR) in working zone. A set of experimental tests has been planned using response surface methodology according to Taguchi matrix (36) with three levels and six factors.The analysis of variance and instruction curves indicate some significant. X1; X4; X6 have a significant effect on the surface roughness Ra for steel, X2 has mildly significant, while X3 and X5 have insignificant effect. The results showed that roughness of workpiece decreased from 0.3 to 0.15 µm that means improved the roughness to 100%.

A surface fitting model is developed based on calorimeter data for two famous brands of household compressors. Correlation equations of ten coefficient polynomials were found as a function of refrigerant saturating and evaporating temperatures in range of (-35℃ to -10℃) using Matlab software for cooling capacity, power consumption, and refrigerant mass flow rate.Additional correlations equations for these variables as a quick choice selection for a proper compressor use at ASHRAE standard that cover a range of swept volume range (2.24-11.15) cm3.The result indicated that these surface fitting models are accurate with in ± 15% for 72 compressors model of cooling capacity and 50 models for power consumption and 25 models for refrigerant mass flow rate.