Physical simulation of finish rolling of microalloyed steels in isothermal conditions
Journal Article

The aim of this work was to establish a temperature of finish rolling stage of Nb/Ti microalloyed steel containing 0.06 wt.% C, 0.77 wt.% Mn, 0.039 wt.% Nb and 0.015 wt.% Ti, using physical simulation. Samples were subjected to laboratory simulation at a twist plastometer at high temperatures, i.e. between 825 and 950 °C. Five pass deformation and interpass times were selected in accordance with a processing parameters at five stand finishing hot strip mill. Restoration (recovery and/or recrystallization) behavior was evaluated by calculation of Fraction Softening (FS) and Area Softening Parameter (ASP) values. At 950 °C all individual pass stress-strain curves, FS and ASP show full recrystallization in all interpass intervals. On the other hand, with a decrease in temperature to the interval of 875-825 °C, the extent of restoration is decreasing, leading to recovery as a sole softening mechanism at 825 °C, which was confirmed by the stress-strain curve shape, and values of FS and ASP. It is assumed that, due to high supersaturation, strain-induced precipitation promoted pinning of grain and subgrain boundaries and suppressed recrystallization. Therefore, the critical temperature for finish rolling was estimated to be 825 °C.

Abdulnaser Hamza Ahmed Fadel, (12-2022), Serbia: Serbian Chemical Society, 76 (4), 227-236

Experimentally Determination of Burst Pressure and Failure Location of Liquefied Petroleum Gas Cylinder
Journal Article

Liquefied Petroleum Gas (LPG) cylinder is a thin pressure vessel used to meet energy requirements in household applications. Bursting of a pressure vessel is disastrous and many fatal accidents are happened due to pressure vessel bursting. The main goal of the current paper is focused to determine experimentally the burst pressures (BP) and failure locations of LPG cylinders. To ensure that the cylinders are in conformance with International Standards. The experiments were carried out on two samples of LPG cylinders used in Libya (C1 and C2). The experimental burst test investigations done by hydrostatic test in which the cylinders were internally pressurized with water. The permanent volume expansions of the LPG cylinders due to internal pressure were also examined. All tests in this study were subject to standard specifications (ISO 4706), which is needed to be conducted on LPG cylinders before introducing them to the Libyan market. Among these tests, the hydro-tests are major tests to be conducted on LPG Cylinders to get approval and acceptance. Hydro-tests on LPG cylinders reveal permanent volumetric expansion of the cylinder, nominal hoop stresses at the time of destruction and the internal pressure at which a cylinder burst. These values are important to ensure that the design and construction of cylinders are safe and compiled to standards.

Abdulnaser Hamza Ahmed Fadel, (12-2021), Libya: University Bulletin, 23 (4), 123-138

Metallographic Techniques for the Determination of the Martensite Transformation Start Forming Temperature in Medium Carbon Vanadium Titanium and Titanium Free Micro Alloyed Steel
Journal Article

The main goal of the current paper is focused to investigate and reveal the importance critical

transition temperatures. Different techniques were used to reveal the critical transition temperatures.

The medium carbon vanadium titanium and titanium free micro alloyed steels tested in this work by

isothermal treatment. In order to reveal experimentally the critical forming temperatures and

compare it by predicted using equations and also describe the influence of alloying elements

on the transformation behavior, martensitic starting formation temperature. This study

has been carried out over a wide range of isothermal treatment temperature (270-350

Abdulnaser Hamza Ahmed Fadel, (12-2021), Libya: Libyan Academy, 3 (3), 1-9

الرقابة على المخزون ودوره في تحسين الإنتاج دراسة حالة- مصنع سيراميك لبدة
مقال في مجلة علمية

يعتبر المخزون من الموضوعات الهامة وفي كل الأنشطة وعلى مختلف المستويات ويوجد في جميع المؤسسات الاقتصادية والخدمية والتجارية وبالتالي كل هذه المؤسسات تحتاج إلى مخازن ومختصين في مجال الرقابة على المخزون يحقق استخدام النماذج الخاصة بالرقابة على المخزون فوائد متعددة للمؤسسات وخاصة المؤسسات الإنتاجية والتي يتعدد ويتنوع مخزونها، وتزداد الحاجة إلى التحكم فيها لضمان استمراريه عملياتها الإنتاجية دون حدوت نقص أو تكدس في المخزون. يعاني مصنع سيراميك لبدة بمدينة زوارة الليبية من انخفاض في الإنتاج عن المستويات المستهدفة نتيجة لعدم وجود أي نظام للرقابة على المخزون مما نتج عنة نقص في كمية المواد الخام وعدم توفيرها في الوقت المناسب، هدفت هذه الدراسة إلى بناء نموذج للرقابة على المخزون والمتمثل في نموذج الكمية الاقتصادية نموذج (ويلسون) من أجل معالجة المشكلة المطروحة والتي تعلقت بكيفية تحديد حجم المخزون الأمثل بما يضمن للمصنع تحسين العملية الإنتاجية ، ومن خلال هذه الدراسة أكتسب الباحث مزيداً من الإلمام المعرفي و خبرة جديدة على الصعيد المهني والأكاديمي، كما تظهر هذه الدراسة أهمية كبيرة من خلال النتائج والتوصيات التي توصل إليها الباحث والتي من شأنها تساهم في تحسين الإنتاج داخل مصنع سيراميك لبدة أما بالنسبة لمنهجية الدراسة تم تقسيمها إلى جانبين جانب نظري اعتمد على الكتب والأدبيات والأطروحات والدراسات السابقة التي تناولت موضوع الدراسة أما الجانب العملي فقد تم استخدام أسلوب دراسة حالة حيث ثم الاعتماد على نموذج رياضي في تطبيق ما تم التطرق إلية في الجانب النظري، وهو نموذج الكمية الاقتصادية المخزون ( نموذج ويلسون) لتجديد حجم المخزون الضروري لتحسين العملية الإنتاجية داخل المصنع. وتوصلت نتائج الدراسة إلى أن بعد ما تم تطبيق نموذج الكمية الاقتصادية على مخزون مادة الفوسفات أدي إلى وجود كمية مخططة من مخزون مادة الفوسفات بكمية اقتصادية تقدر بحوالي 740.65طن وبعدد فترات توريد مخططة حوالي 7 توريدات في السنة أي ((738.46*6.5 = 4800 طن في السنة) أدي إلى تحسن في معدل نمو إنتاجية المصنع من (-3.3) في سنة 2017م إلى (6.6) عن سنة 2018م.

وأوصت الدراسة بجملة من التوصيات أهمها وضع برامج لتوعية العاملين بالمخازن حول استخدام نظام الرقابة على المخزون ومدى ضرورتها داخل المصنع كما يوصي الباحث بضرورة استخدام نموذج الكمية الاقتصادية وفق الاحتياجات المطلوبة وذلك من أجل استمرار العملية الإنتاجية داخل المصنع دون انقطاع، كما يوصى الباحث بالاعتماد على مقاييس التقييم في تقييم إدارة الإنتاج وقسم المخازن ومقارنة الأداء الفعلي مع الأداء المخطط تم تصحيح الانحرافات إن وجدت كما أوصى الباحث بضرورة تطبيق المادة (135) من لائحة العقود الإدارية والتي تنص على فرض غرامات تأخير لا تتجاوز 5% من قيمة العقد على الموردين في حال تأخر الموردين في توريد البضاعة عن موعدها.


عبدالحميد عمار منصور النائض، أ. علي خليفة عمار دربال، (09-2021)، مجلة الأكاديمية للعلوم الأساسية والتطبيقية: الأكاديمية الليبية، 3 (3)، 1-14

Effect of Isothermal Heat Treatment Temperature and Time on Microstructure and Mechanical Properties of Titanium Free Medium Carbon Micro Alloyed Steel
Journal Article

The main goal of the current paper is focused to investigate the effect of isothermal heat treatment

temperature and time on microstructure and strength in a medium carbon vanadium titanium free micro

alloyed steel. Isothermal heat treatment was carried out in the temperature range 350 to 600 C° at

different holding times varying from 2s to 1200s followed by water quenching. Samples were

investigated using optical microscope (OM) and scanning electron microscopy (SEM) paired with

energy dispersive spectroscopy (EDS) and by compressive testing using a servo-hydraulic testing

machine. The results show that, the final microstructure of samples held at high temperatures (550 and

600°C) consists of polygonal intra-granularly nucleated ferrite idiomorphs, combined with grain

boundary ferrite and pearlite were produced and followed by retained austenite that transformed to

martensite upon quenching (incomplete transformation phenomenon). At intermediate temperatures

(450 and 500 °C) an interlocked acicular ferrite (AF) microstructure is produced, hence acicular ferrite

becomes prevalent in the microstructure at (450 °C). The microstructure after the heat treatment at

500°C consists coarse nonpolygonal ferrite grains separated by pearlite colonies. However, at low

temperatures (400 and 350°C), the final microstructure of the samples held at 350°C consists of

bainitic sheaves, where the sheave of parallel acicular ferrite plates, similar to bainitic sheaves but

intra-granularly nucleated were observed, which called in some references as sheaf type acicular ferrite

for samples isothermally treated at 400°C. Yield stress was determined by compression testing on samples

with final Microstructure, the results show that, the observed change in the microstructure is related by a

marked decrease of compressive yield strength, approximately from 1000 to 700 MPa.

Abdulnaser Hamza Ahmed Fadel, (06-2021), Libya: Libyan Academy, 1 (3), 1-9

Mechanization the traditional admission systems and their role in improving the quality of inputs for higher education institutions
مقال في مجلة علمية

This study aims to build a model for a unified electronic admission system for Libyan higher education institutions. It has been noticeable that tertiary institutions in Libya have poor outcomes, and perhaps one of the reasons for that is the presence of defects in the current admission systems and their policies, which leads to selecting and accepting inappropriate applicants. The admission systems in most Libyan higher education institutions are outdated and still based on paper applications.Hence, this research was conducted to look at the Arab experiences in employing technology to develop admission systems at higher educational institutions. The research was also conducted to determine whether those Arab experiences can be applied to our local tertiary institutions, and see if they can they improve the quality of higher education outcomes. The researchers critically reviewed a number of tertiary admission systems and procedures offered at some educational institutions in Arab countries to reach an appropriate proposal for an online admission system to use at higher education institutions in Libya. The target admission system aims to offer many advantages and benefits such as saving time and effort for students and workers, as well as speeding up the processes of admission applications and checking application statuses.


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عمر صالح محمود جمعة، (03-2021)، سبها: مجلة جامعة سبها للعلوم البحثة و التطبيقية، 20 (3)، 28-35

Structure and Strength of Isothermally Heat-Treated Medium Carbon Ti-V Microalloyed Steel
Journal Article

Isothermal transformation characteristics of a medium carbon Ti-V microalloyed steel were

investigated using light microscopy, scanning electron microscopy (SEM) equipped with energy

dispersive spectroscopy (EDS), and by uniaxial compressive testing. Samples austenitized on 1100 C

were isothermally treated in the range from 350 to 600 C and subsequently water quenched. The

final microstructure of the samples held at 350 C consisted of bainitic sheaves and had compressive

yield strength, approximately from 1000 MPa, which is attributed to high dislocation density of

low bainite. At 400 and 450 C, acicular ferrite became prevalent in the microstructure. It was also

formed by a displacive mechanism, but the dislocation density was lower, leading to a decrease of

compressive yield strength to approximately 700 MPa. The microstructure after the heat treatment at

500 C consisted of coarse non-polygonal ferrite grains separated by pearlite colonies, principally

dislocation free grains, so that the compressive YS reached a minimum value of about 700 MPa. The

microstructure of the samples heat-treated at 550 and 600 C consisted of pearlite and both grain

boundary and intragranular ferrite, alongside with some martensite. After 600 s, austenite became

stable and transformed to martensite after water quenching. Therefore, the presence of martensite

increased the compressive YS to approx. 800 MPa.

Abdulnaser Hamza Ahmed Fadel, (01-2021), Switzerland: Metals 2021, 11 (1011), 1-12

Modeling and Control of Car Active Suspension System Using a Neural Network-based Controller and Linear Quadratic Regulator Controller
Conference paper

This paper aims to demonstrate the application of two different control techniques, namely the Linear Quadratic Regulator (LQR) and a neural network-based controller to evaluate and control the vibrations that occurred in the car's suspension system. When the car suspension is designed, a quarter car model with 1-DOF is used. A complete control system is needed to provide the desired suspension performance and characteristics such as passenger comfort, road handling, and suspension deflection, this control system performed by using the Matlab software and includes three parts: input signals (actuator force and road profile), Controller, and the suspension system model. The simulation results show a comparison between the uncontrolled suspension system and the suspension system with a neural network-based controller and the active suspension system of the car based on the linear-quadratic regulator, and it is explained thoroughly.

Omer Saleh Mahmod Jomah, (01-2021), 10.1109/ICECOCS50124.2020.9314426: IEEE, 1--25

Pearlitic Transformation by Isothermal Decomposition in Titanium and Titanium Free Micro Alloyed Steel
Journal Article

This work is focused on nucleation stages during isothermal austenite decomposition in two medium carbon Vanadium Ti / Ti free micro alloyed steels. Isothermal treatment was carried out in the temperature range 350 to 600οC. Metallographic evaluation using optical and scanning electron microscopy (SEM) enabled determination of the nucleation onset phases of isothermally decomposed austenite. Mainly three phases are found to be relevant to this initiation stage of transformation: first is related to grain boundary nucleated ferrite (GBF), second is related to intra-granularly nucleated ferrite (IGF) and the third to pearlite (P). GBF and IGF are divided into the high temperature and the low temperature segments as consequence of either displacive or diffusion nature of transformation. Addition of titanium to V – micro alloyed steel in this work seems to be balanced by a slightly higher C and Mn content, leading to limited effect on nucleation stage of austenite decomposition. The results show that during continuous cooling, onset of pearlite phase can take place. It occurs at temperatures ≥ 500 C°, followed by an incomplete reaction phenomenon. The main characteristics of pearlite is always nucleated on the surface between proeutectoid ferrite and austenite. Incubation time for onset of pearlite decrease with decrease of temperature.

Abdulnaser Hamza Ahmed Fadel, (12-2020), Libya: Libyan Academy, 2 (2), 1-6

Vibration Monitoring of the Gradual Worn in Journal Bearings
Conference paper

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Osama Amhammeed Altaher Hassin, (08-2020), Huddersfield, UK: COMADEM, 1-5