Engineering and Technology Journal

In the current research, Magnesium oxide II (MnO2) nanostructures were prepared by chemical route from hydro manganese chloride salt using Potassium hydroxide as reducing agent. X-Ray diffraction (XRD), SEM and Fourier transformation infrared (FTIR) used to characterize both particle size and structure of MnO2 nanoparticles. XRD results confirmed impurity of synthesized powder with α-MnO2 as predominant phase. The average particle size of manganese dioxide was in the range 25- 30 nm. Photographs of scanning
electron microscope (SEM) showed two hierarchical structures, cluster
agglomeration and chain appearance.

Built-in Self-test (BIST) is one of integrated circuit (IC) testing techniques that can be used as a pseudo-random generator for the Circuit Under Test (CUT). This paper introduces the design and simulation of a 4-bit test pattern generator (TPG) using a one dimension Linear Hybrid Cellular Automata (LHCA) with a mixture of rule 90 and 150. LHCA is an enhancement from Linear Feedback Shift Register (LFSR) which can have more random test vectors and improving the cycle length. Design and simulation have been performed using Quartus II and Model Sim software.

This work presents an investigation of possibility incorporate of synthetic fibers (glass, nylon and carbon) at two states (short: 1cm, long: 5cm) effects on the mechanical properties of mortars (cement: sand composition (1:3)). Fibers materials used at different weight percentages ranged of (0, 0.4, 0.8, and 1.2) wt%. Density, water absorption, porosity, thermal conductivity, compressive strength and flexural strength experimentally investigated for mortar specimens after curing for (28 days). The results showed that the incorporation of these fiber materials improvement mechanical and physical tests for all reinforced samples with short and long fibers, and that the highest value of the mechanical and physical properties obtained from long fiber (5cm) reinforced cement samples with (1.2%Nylon), reaching the rate of increase in values of compressive strength by (17.74%), flexural strength by (52.8%), and water absorption by (4.54%), while reaching the rate of decrease in values of density by (5.32%). The higher values for short fiber (1cm) reinforced samples reaching the rate of increase in values of compressive strength by (10.92%), flexural strength by (40.65%), and water absorption by (6.65%), while reaching the rate of decrease in values of density by (8.91%). Results of thermal conductivity test showed decrease in values conductivity for all mortar samples with long short synthetic fibers and that the minimum value of conductivity obtained with (1.2%Carbon), reaching the rate of increase in values of thermal conductivity by (41.84%) for long fiber reinforced samples, while the lowest value for conductivity by (75.98%) for short fiber reinforced samples.

The main problem of traditional LC ( L represents the inductance, and C represents the Capacitance) Voltage Controlled Oscillators VCOs, is the non-linearity relation between the tuning control voltage and output resonance frequency, which is caused by two following reasons: the first one is the inverse and non-linear relation between the tuning control voltage and produced capacitance of the used varactor diode in the VCO circuit, and the second is the inverse and non-linear relation between the capacitance value of the used varactor diode and the output resonance frequency. In this paper, a proposed circuit has been designed and implemented to solve this problem and realize a direct-linear relation between the tuning control voltage and output resonance frequency for the LC Voltage Controlled Oscillator that utilize the varactor diode as a voltage controlled capacitance. The proposed circuit has been realized using Logarithmic, Inverting, Ant-Logarithmic, and Difference Amplifiers, which they are characterized by their simplicity and low cost. The theoretical and practical results of testing the proposed circuit had been presented using MATLAB software package. The proposed work has been practically tested by 21 measurement points, whereas, it has exhibited stimulant results that supports the successfulness of its design and performance.

The present investigation aims to perform experimental study to show the feasibility of application composite materials as secondary roofs, as well as their capability for reducing cooling load in building. Moreover, compare some of their mechanical properties and acoustic insulation with conventional secondary roofs. Three basic models, which are common, were chosen for the construction of buildings' roofs in Baghdad (concrete and concrete tiles as basic components of the first model, brick and clay tiles as basic components of the second model and brick and normal tiles as basic components of the third model). In addition, three composite materials were used in present work (fiber glass+ Nylon 66, fiber glass+ one layer of date palm cortex and fiber glass+ two layers of date palm cortex). The gypsum plates have been selected as a conventional secondary roofs when performing calculations and comparison. The results show that using proposed composite materials leads to significant reduction in cooling load by about 69.56 %, 65.3 % and 65.5 % respectively for the three models. In addition, the comparison of acoustic insulation shows that the proposed materials offer good acoustic insulation. Moreover, these materials able to afford external shocks better.

Friction stir processing (FSP) is an innovative technique of varying the metallic features by intense, local plastic deforming. Accordingly, materials are stirred with no altering the phase via melting or otherwise to produce a microstructure with equiaxed and fine grains. This method enhances the microstructural features of metals. In This study the microstructure and the mechanical features including (tensile strength and microhardness), and radiographic inspection results are studied. All specimens of pure copper use in the (FSW) and (FSP) have variable rotating speed (900, 1200, and 1600 rpm) with constant feed speed (40 mm/min). The most remarkable results, the ultimate tensile strength for FSW and FSP at (1200 RPM and 40 mm/min) with the values of 250.4 MPa for FSW and 261..2 MPa for FSP and the efficiency reached 92.7% and 96.3% for FSP and FSW, respectively. The high hardness in the same sample was 118 HV for FSW and 135 HV for FSP. The microstructure at welding zones, specially nugget zone, is improved by the friction stir processing. Radiographic examination showed incomplete fusion of welding joint without defect.

In this paper, the force production mechanism in partitioned stator flux reversal permanent magnet (PS-FRPM) linear machine will be investigated. Since the PS-FRPM linear machine has both armature windings and the permanent magnet (PM) in one machine part and the other part is passive; thereby, the force production mechanism in conventional PM linear machine, is not valid for such a machine. In order to determine both magnetic and electrical loading frequency components, which result in production the electromagnetic force a spatial harmonic analysis is adapted. It has been found that the electromagnetic force in the PS-FRPM linear machine is produced by the interaction of the fundamental and its non-triple multiples harmonic orders of the stator winding magneto-motive force (MMF) with the air gap flux density, which is equal to the product of the PM (MMF) and the air gap permeance accounting for both the mover pole and the upper stator teeth. The analytical results are validated by finite element analysis (FEA), which are shown good agreement.

In this paper, a new filter is constructed by inserting two slots in the form of rectangular open loop resonator with folded ends. The insertion of these slots has successfully led to the compact size and the dual bandwidth behavior. The overall filter dimensions are 16×12 mm2, which correspond to 0.61λg × 0.4λg using a substrate with Rogers Ro 4003 with a relative permittivity of 3.38 and thickness of 1.0 mm. The resulting structure exhibits a dual-band behavior. The first passband has a center frequency of 6.2 GHz with FBW of 16.833% and input reflection coefficient better than -30 dB and insertion loss is approximately equal to -0.3 dB. In the second passband, the center frequency is 9.6 GHz, and the FBW is 12.57% with an input reflection coefficient better than -25 dB and insertion loss is approximately equal to -0.5 dB. The transmission zero is located between the dual passbands at 7.8 GHz with over -28.66 dB of the stopband. The simulation and performance evaluation of the proposed filter have been carried out using Microwave Studio Suite of Computer Simulation Technology (CST). As a result, this makes the proposed filter candidate for operating in satellite applications.

It is generally accepted that the summer in Iraq is relatively hot season, where the temperature sometimes reaches 60 Cº. Accordingly, most of the Iraqi houses are characterized as having a large area of windows with a single glass, which could be resulted in a significant loss in cooling energy. Hence, the present research concern is to examine the effect of using double glass windows (as an alternative to single glass) on the saving in which energy normally used in houses and buildings at July and August for different hours 3, 6, 9, 12, 15, 18, 21 and 24 P.m. A practical and realistic study was conducted. Three values of aspect ratio are used 30, 15 and 10 for the presence of air between the panels and in the presence of the argon gas for aspect ratio, 10 were practically investigated. The experimental results confirmed that using of the double glass with the presence of air as a medium for heat transfer between the two panels could be reduced the amount of heat transferred compared to that of single glass between (45-78), (54-85) and(58-88)%, while for argon it was (60-91)%.

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A material scientists worldwide has investigated optical plastics as alternative materials for glasses that have been widely used over the years. Plastics have numerous advantages over glasses in optical applications, especially in ophthalmic applications. Recently, researchers have developed new polymer materials to satisfy the ophthalmic industry requirements. Mechanical, chemical and physical tests were conducted to determine the polymers for contact lenses. In this study, the optical properties of polymers were evaluated and analyzed by using Zemax program depending on Liou & Brennan model. The effect of achromatic and polychromatic light on the performance of the polymers contact lenses was investigated. The modulation transfer function (MTF) and root mean square spot size (RMS) were the two criteria for analyzing the results and determining the effect of chromatic aberration on different polymers contact lens performances.