Al-Khwarizmi Engineering Journal

A dynamic analysis method has been developed to investigate and characterize embedded delamination on the dynamic response of composite laminated structures. A nonlinear finite element model for geometrically large amplitude free vibration intact plate and delamination plate analysis is presented using higher order shear deformation theory where the nonlinearity was introduced in the Green-Lagrange sense. The governing equation of the vibrated plate were derived using the Variational approach. The effect of different orthotropicity ratio, boundary condition and delamination size on the non-dimenational fundamental frequency and frequency ratios of plate for different stacking sequences are studied. Finally the discrepancy of the results was 17.4906% when the severe nonlinearity is considered

The effect of solution heat treatment on the mechanical properties of Aluminum-Copper alloy. (2024-T3) by the rolling process is investigated. The solution heat treatment was implemented by heating the sheets to 480 C° and quenching them by water; then forming by rolling for many passes. And then natural aging is done for one month. Mechanical properties (tensile strength and hardness) are evaluated and the results are compared with the metal without treatment during the rolling process. ANSYS analysis is used to show the stresses distribution in the sheet during the rolling process. It has been seen that good mechanical properties are evident in the alloy without heat treatment due to the strain hardening and also the mechanical properties are improved after heat treatment and rolling process but with lower forces and stresses when compared with the untreated.

A comprehensive practical study of typical mechanical properties of welded Aluminum alloy AA7020-T6 (Al-Mg-Zn), adopting friction stir welding (FSW) technique and conventional metal inert gas (MIG) technique, is well achieved in this work for real comparison purposes. The essences of present output findings were concentrated upon the FSW samples in respect to that MIG ones which can be summarized in the increase of the ultimate tensile strength for FSW was 340 MPa while it was 232 MPa for MIG welding, where it was for base metal 400 MPa. The minimum microhardness value for FSW was recorded at HAZ and it was 133 HV0.05 while it was 70 HV0.05 for MIG weld at the welding metal. The FSW produce 2470 N higher than MIG welding in the bending test and a decrease in the localized grain size for FSW in the stirred zone 12 µm and it was 37 µm for MIG while it was 32 µm for the base metal

The objective of this study was tointroduce a recursive least squares (RLS) parameter estimatorenhanced by using a neural network (NN) to facilitate the computing of a bit error rate (BER) (error reduction) during channels estimation of a multiple input-multiple output orthogonal frequency division multiplexing (MIMO-OFDM) system over a Rayleigh multipath fading channel.Recursive least square is an efficient approach to neural network training:first, the neural network estimator learns to adapt to the channel variations then it estimates the channel frequency response. Simulation results show that the proposed method has better performance compared to the conventional methods least square (LS) and the original RLS and it is more robust at high speed mobility.

The work in this paper involves the planning, design and implementation of a mobile learning system called Nahrain Mobile Learning System (NMLS). This system provides complete teaching resources, which can be accessed by the students, instructors and administrators through the mobile phones. It presents a viable alternative to Electronic learning. It focuses on the mobility and flexibility of the learning practice, and emphasizes the interaction between the learner and learning content. System users are categorized into three categories: administrators, instructors and students. Different learning activities can be carried out throughout the system, offering necessary communication tools to allow the users to communicate with each other through forums, SMS and e-mails. NMLS platform is based on 3G mobile phone technology and adopted WAP as a solution for the system platform. The NMLS framework is based on three layers, which are presentation layer, business logic layer and data layer.

The study aims mainly to evaluate the performance of Sharq Dijila water treatment plant in removing turbidity for the period of 1-4-2001 to 31-3-2004. Daily data for turbidity of raw, clarified, filtered, and supplied water were analyzed. The results of the study showed that there is a wide variation in turbidity levels of raw water fluctuating between 10-1000 NTU with mean value of 41.3 NTU. Turbidity values of the clarified water varied between 1.4-77 NTU. Based on the turbidity value of 10 NTU and 20 NTU (the design maximum turbidity) the readings gave an acceptable percentage of 32.4% and 86% respectively. The turbidity of filtered water ranged between 0.2-4.5 NTU which are completely in compliance with Iraqi and WHO standards. In accordance with the American Environmental Protection Agency (USEPA) and based on the analysis of 2-day moving average of 5 NTU and 30-day moving average of 1 NTU, it was found that the filters operated at acceptable percentage of 100% and 45% respectively. Turbidity value of the supplied water averaged between 0.4-9.5 NTU which is higher than the turbidity of the filtered water due to the mixing of the water from all other filters. Also turbidity values from the unwashed filters are higher than the washed filters and the precipitation in the treated water reservoir. Based on the Iraqi Drinking Water Standard, USEPA 2-day and 30-day moving average, the supplied water was within the permissible limits of 98%, 98.6%, and 98.6% respectively.

In this paper the process of metal ions extraction (Zn(II) and Cu(II)) was studied in PEG-KCl aqueous two phase system was investigated without using an extracting agent. The experimental runs were performance at constant temperature (25 oC), constant mixing time (30 min), and constant PH of the solution (about 3). The effect of KCl salt concentration (from 10% to 25%), volumetric phase ratio of PEG solution to KCl solution (from 0.5 to 2), and the initial metal ion concentration (from 0.25 ml to 2 ml of 1 gm/L solution) were investigated on the percent extraction of Zn(II) and Cu(II). The results indicated that the percent extraction of metal ions increase with increasing of salt concentration and phase ratio, and slightly decrease with increasing of initial metal ion concentration.

This research was to determine the effect of rare earth metal (REM) on the as-cast microstructure of Mg-4Al alloy.
The rare earth metal used here is Lanthanum to produce Mg-4Al-1.5La alloy. The microstructure was characterized by
optical microscopy. The phases of this alloy were identified by X-ray diffraction. The microstructure of Mg-4Al
consists of α-Mg and grain boundaries with precipitated phase particles. With the addition of Lanthanum, three distinct
phases were identified in the X-ray diffraction patterns of the as cast Mg-4Al-1.5La: Mg, Al11La3, Al4La. The Mg17Al12
phase was not detected. The addition of Lanthanium increases the hardness and decrease the wear rate of Mg-4Al.

تعتبر الضوضاء الناتجة عن المحركات والأنواع المختلفة من الانظمة كملوث ابتداءا من عام 1990، ويمكن تعريف الضوضاء (بالصوت غير المرغوب به)، وفي المستويات العالية يمكن اعتبارها خطره على الصحه، وتنتج المحركات الكبيرة مستويات عالية من الضوضاء. ويوجد في عدة دول قوانين تحدد المستويات المقبولة من الضوضاء المسموح بها في غرف المحركات المغلقة في السفن والتطبيقات الثابتة، وتعد الضوضاء الناتجة من السيارات أقل تأثيرا لوجود التقنيات القادرة على التحكم و السيطرة عليها.
في هذا البحث أجريت دراسة على محرك احتراق داخلي ذو اسطوانة واحدة يعمل باضاقة الايثانول الى الكازولين، وأخذت البيانات لسرع متعددة، بدون اضافة ومع اضافة ايثانول بنسبة 10 و 20%، وبدون استخدام عازل صوتي ومع استخدام عازل وعازلين، أظهرت النتائج أن طبيعة الصوت المنبعث أحادي القطب، كما أن الضوضاء تزيد بزيادة عدد دورات المحرك، وأن اضافة الكحول لا تؤثر كثيرا على مقدار الصوت المنبعث من المحرك، كما أثبتت الدراسة أن استخدام عازل صوتي واحد يكفي لتقليل الضوضاء بنسبة عالية.