Microstructural Evolutions, Hot Deformation and Work Hardening Behaviour of Novel Al–Zn Binary Alloys Processed by Squeezing and Hot Extrusion

S. Sivasankaran,K. R. Ramkumar,Hany R. Ammar,Fahad A. Al‑Mufadi,Abdulaziz S. Alaboodi,Osama Mohamed Irfan 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.4

The main goals of this work were to manufacture novel Al–Zn extruded alloys by varying the Zn content (0, 10, 20, 30 wt%),investigate the microstructural evolutions, hot deformation, and work hardening behaviour by hot compression test at differenttemperatures (25 °C, 75 °C, 150 °C, 225 °C, 300 °C). Al–20Zn alloy microstructure revealed α-Al and uniform distributionof (α + η) phases, coherent (α + η) crystals in GBs with casting defect-free surfaces, and effective interactions of pinningdislocations which led to improve mechanical performance of Al–20Zn alloy, as compared to the other alloys. The observedengineering stress–strain curve results revealed the decrease of stress with increasing of temperature due to flow softening,dynamic recovery and dynamic recrystallization. These results displayed also an increase of stress value with increasingof Zn content due to the precipitation of high density (α + η) phase in the matrix and GBs, increasing of forest and mobiledislocations density with strain fields, and the formation of fine dendrites. Work hardening rate (WHR) of extruded samplesdisplayed three stages: stage I, WHR decreased slightly with increasing of temperature up to 75 °C and decreased drasticallyfrom 75 °C to 300 °C due to softening; stage II, WHR maintained constant due to balance between dislocation generationsand dislocation annihilation; stage III, WHR slightly increased due to strain hardening of (α + η) phase. WHR was observedto increase considerably with increasing of Zn content due to the formation and dispersion of high density of (α + η) phasein the Al matrix and GBs. Deformation micro-localization in terms of different characteristics was examined and reportedon the deformed samples after hot-compression test through SEM micrographs.

Finite element based modeling and thermal dynamic analysis of functionally graded graphene reinforced beams

Al-Maliki, Ammar F.H.,Ahmed, Ridha A.,Moustafa, Nader M.,Faleh, Nadhim M. Techno-Press 2020 Advances in computational design Vol.5 No.2

In the present research, dynamic analysis of functionally graded (FG) graphene-reinforced beams under thermal loading has been carried out based on finite element approach. The presented formulation is based on a higher order refined beam element accounting for shear deformations. The graphene-reinforced beam is exposed to transverse periodic mechanical loading. Graphene platelets have three types of dispersion within the structure including uniform-type, linear-type and nonlinear-type. Convergences and validation studies of derived results from finite element approach are also presented. This research shows that the resonance behavior of a nanocomposite beam can be controlled by the GPL content and dispersions. Therefore, it is showed that the dynamical deflections are notably influenced by GPL weight fractions, types of GPL distributions, temperature changes, elastic foundation and harmonic load excitation frequency.

Finite element formulation and vibration of nonlocal refined metal foam beams with symmetric and non-symmetric porosities

Al-Maliki, Ammar F.H.,Faleh, Nadhim M.,Alasadi, Abbas A. Techno-Press 2019 Structural monitoring and maintenance Vol.6 No.2

In present article, a size-dependent refined thick beam element has been established based upon nonlocal elasticity theory. Next, it is used to explore vibration response of porous metal foam nanobeams on elastic medium. The established beam element introduces ten degrees of freedom. Different porosity distributions called uniform, symmetric and asymmetric will be employed. Herein, introduced thick beam element contains shear deformations without using correction factors. Convergence and verification studies of obtained results from finite element method are also provided. The impacts of nonlocality factor, foundation factors, shear deformation, slenderness ratio, porosity kinds and porosity factor on vibration frequencies of metal foam nano-sized beams have been explored.

Synchronous Reference Frame Theory Based Intelligent Controller for Current THD Reduction

Al-Ammar Essam A.,Ul Haq Azhar,Iqbal Ahsan,Ko Wonsuk,Jalal Marium,Anjum Muhammad Almas,Choi Hyeong-Jin,Kang Hyun-Koo 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.6

Concerns related to current harmonics have gained increased attention in recent years due to technological advancement in power electronics and the proliferation of non-linear loads in power distribution system. It has become challenging to limit current total harmonic distortion (THD) at consumer end mainly due to increased penetration of intermittent switching based non-linear loads. Shunt active power fi lter (SAPF) is considered a marvelous power electronics device to tackle consumer side current harmonics. This paper presents a synchronous reference frame (SRF) based improved control method for compliant working of SAPF to reduce current harmonics in the distribution network with same and diff erent THD levels in three phases. This research work investigates an eff ectual DC link voltage control technique linked with SRF based control of SAPF to eff ectively mitigate current harmonics. A fuzzy logic-based automatic switch (FLBAS) is designed according to the THD standards of IET and IEEE for real-time controlling of SRF based control of SAPF. In addition, S-plane stability analysis of the proposed control scheme is performed using the model of SAPF’s inverter. It is established that the closed-loop system is asymptotically stable with the proposed control scheme. The presented simulation results validate the eff ectiveness of the proposed control technique for SAPF robustly.

An Anti-Overload Model for OpenStack Based on an Effective Dynamic Migration

( Al-moalmi Ammar ),( Juan Luo ),( Zhuo Tang ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.9

As an emerging technology, cloud computing is a revolution in information technology that attracts significant attention from both public and private sectors. In this paper, we proposed a dynamic approach for live migration to obviate overloaded machines. This approach is applied on OpenStack, which rapidly grows in an open source cloud computing platform. We conducted a cost-aware dynamic live migration for virtual machines (VMs) at an appropriate time to obviate the violation of service level agreement (SLA) before it happens. We conducted a preemptive migration to offload physical machine (PM) before the overload situation depending on the predictive method. We have carried out a distributed model, a predictive method, and a dynamic threshold policy, which are efficient for the scalable environment as cloud computing. Experimental results have indicated that our model succeeded in avoiding the overload at a suitable time. The simulation results from our solution remarked the very efficient reduction of VM migrations and SLA violation, which could help cloud providers to deliver a good quality of service (QoS).

The Effect of Social Marketing on Customer Behavior: An Empirical Study of Tourism Companies in Baghdad, Iraq

Hiba Ammar AL-KUBAISI,Noor Khalil IBRAHIM 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.8

Social marketing seeks to develop and integrate marketing concepts with other approaches to social change and aims to influence behaviors that benefit individuals and societies for the social good. The study investigates the type and level of influence of social marketing on customer behavior in tourism companies in Baghdad (Iraq). The sample size of the study is 135 people comprising directors, assistant directors, and marketing staff in tourism companies in Baghdad. A questionnaire was used as a tool to collect data and information, and was prepared by the researcher after it underwent validity, stability, and arbitration tests. The data was analyzed using the statistical program (SPSS v. 25, AMOS v.23) and statistical methods have been used to process the data represented by the arithmetic mean, standard deviation, coefficient of variation, correlation coefficient (Person), simple and multiple regression equations. The research showed significant results represented by a positive and strong relationship between the research variables. This result indicates that there is an effect on the customer’s behavior. Moreover, the results of the study showed positive effects that extend from social marketing to customer behavior in the long term.

Experimental Investigation of Joint Filling Materials Performance on Preventing Seepage in Lined Open Concrete Canal (Laboratory and Field Model)

Aqeel Al-adili,Osama Abd Al-ameer,Ammar Al-sharbati 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.5

Seepage is one of the most serious problems of water loss in the irrigation canals. In Iraq, most projects of concrete lining irrigation canals suffer from seepage losses phenomena through joints. The loss of water due to seepage from irrigation canals constitutes a substantial part of the usable water. The aim of this study is to reduce or prevent the seepage by using new alternative joints filling materials. The methodology in this study follows two main categories for calculating and studying the seepage and efficiency of some alternative materials, hoping to apply a new filling joint material, and assessing their performance to prevent seepage. The first category was done by constructing a trapezoidal concrete canal model. The joints filling materials used in this research were : cement-sand mortar, cement-sand mortar with Styrene Butadiene Rubber (SBR), cement-sand with Krystol Internal Membrane (KIM), and Setseal B (liquid polymer with powder). The average percentage of seepage losses was reduced to about 11.3, 29, and 89% when using cement-sand mortar and SBR, cement-sand mortar and KIM, and Setseal B respectively, as joints filling material instead of cement-sand mortar (the initial filling material). While when using Setseal B as a coating material for 9 months duration give no seepage (zero seepage). The second category was carried out by field study, which was done on a branch of irrigation concrete Setseal B as a coating layer was applied on the existing cement-sand joints of the canal (based on the results of the laboratory model tests). It has been tested for 3 weeks. The average reduction percentage in water losses was about 62.5%, by comparing it with using cement-sand mortar only as joints filling material.

Nitrogen Fertilizer Management Control For Tomato Production Under Greenhouse Conditions Using quick In-Situ Sap Tests

Ali Abdullah Al Jaloud,Mohamed Ammar Errebhi,Sami S. Al Barih,Mirza Shaheen Baig,Ammar A. Al Askar 한국원예학회 2006 한국원예학회 기타간행물 Vol.- No.-

Experimental and numerical investigation of reinforced concrete beams containing vertical openings

Jafarali Parol,Ammar Ben-Nakhi,Shaikha Al-Sanad,Jamal Al-Qazweeni,Hamad J. Al-Duaij,Hasan Kamal 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.72 No.3

Horizontal openings in reinforced concrete (RC) beams are quite often used to accommodate service pipelines. Several research papers are available in the literature describing their effect. RC beams with vertical openings are commonly used to accommodate service lines in residential buildings in Kuwait. However, there are lack of design guidelines and best practices reported in the literature for RC beams with vertical openings, whereas the detailed guidelines are available for beams with horizontal openings. In the present paper, laboratory experiments are conducted on nine RC beams with and without vertical openings. Parametric study has been carried out using nonlinear finite element analysis (FEA) with changes in the diameter of the opening, various positions of the opening along the length and width of the beam, edge distance, etc. 50 finite element simulations were conducted. The FEA results are verified using the results from the laboratory experiments. The study showed that the load carrying capacity of the beam is reduced by 20% for the RC beam with vertical openings placed near the center of the beam compared to a solid beam without an opening. Significant reduction in load carrying capacity is observed for beams with an opening near the support (≈15%). The overall stiffness of the beam, crack pattern and failure modes were not affected due to the presence of the vertical opening. Furthermore, an artificial neural network (ANN) analysis is carried out using the FEA generated data. The results and observations from the ANN and FEA are in good agreement with experimental results.

Synthesis, Microstructures and Mechanical Behaviour of Cr0.21Fe0.20Al0.41Cu0.18 and Cr0.14Fe0.13Al0.26Cu0.11Si0.25Zn0.11 Nanocrystallite Entropy Alloys Prepared by Mechanical Alloying and Hot-Pressing

Yaser A. Alshataif,S. Sivasankaran,Fahad A. Al‑Mufadi,Abdulaziz S. Alaboodi,H. R. Ammar 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.1

Four component Cr0.21Fe0.20Al0.41Cu0.18medium entropy alloy (Quaternary, 4C-MEA) and six componentCr0.14Fe0.13Al0.26Cu0.11Si0.25Zn0.11high entropy alloy (sexinary, 6C-HEA) were designed and developed in non-equiatomicratio to attain improved mechanical properties. These 4C-MEA, and 6C-HEA were synthesized via mechanical alloying(MA), and consolidated by hot pressing (HPing) at 723 K. For comparison, the same atomic ratio of four and six componentsof coarse grain alloys (4C-CGA and 6C-CGA) were also manufactured by conventional blending method. Nanocrystallitesize powders of 27 ± 5.20 nm and 38 ± 3.7 nm were achieved for 4C-MEA and 6C-HEA respectively after 20 h MA. Thephase evolutions, structural properties, and powder surface morphologies were characterized using X-ray diffraction andseveral electron microscopes. The 4C-MEA has possessed more quantity of body centred cubic (BCC) and less amountof face centred cubic (FCC) phases due to the more solid dissolution of 4 components. However, 6C-HEA exhibited morequantity of FCC and a small amount of BCC phases due to the incorporation of more FCC components compared to 4C-MEAand less solid dissolution due to more atomic radius difference among the mixing elements (atomic radius of Cr = 166 pm,Fe = 156 pm, Al = 118 pm, Cu = 145 pm, Si = 111 pm and Zn = 142 pm). The HPed samples produced ultra-fine crystallitesize of 177 nm and 499 nm for 4C-MEA and 6C-HEA respectively. Further, 4C-MEA and 6C-HEA exhibited the ultimatecompressive strength (UCS) of 365 MPa and 456 MPa respectively due to dissolution and lattice distortion of mixing elements. Also, 6C-HEA possessed Vickers hardness strength of around 1.97 GPa which was 2 times higher than 4C-MEA. The theoretical background of various strengthening mechanisms, various physicochemical, thermodynamic parameters, andfour core effects behind the improved properties in entropy alloys was discussed and reported. The dislocation strengtheningand solid solution strengthening were the major factors in exhibiting more UCS in 4C-MEA and 6C-HEA than 4C-CGAand 6C-CGA.