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.

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.

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.

Vehicle safety and control is attracting attention increasingly in an attempt to improve the stability and manoeuvrability of vehicles. Three degrees of freedom vehicle dynamic model (called planar vehicle model) is established. Based on theories of fuzzy PID control and neural network based-Controller, controller of vehicle stability is designed by using the method of direct yaw rate control and the two different control strategies. The controllers were compared under one road condition which is a lane change of manoeuvre. By comparing and analyzing the control effect of fuzzy PID control and neural network based-Controller, the result shows as follows: the two controllers improved the yaw rate to follow the reference yaw rate but, using the fuzzy PID controller gave a better and closer path for the desired path of yaw rate compared to using of the neural network controller.

In this paper we want to describe the algorithm to find all good starting points for

iteration of 𝑁𝑝(𝑧) to find all the roots of 𝑝(𝑧) by quick and easy way. So in this paper

we have proved that all critical points go to the roots under iteration of Newton’s

function then it will be the good starting points for iteration of 𝑁𝑝(𝑧) .

The role of email is becoming more and more important and email is considered one of the most effective tools of communication and correspondence nowadays. This research paper investigates the use of etiquette by Libyan EFL postgraduate students in writing formal emails. The aim is to shed light on the situation and determine to what extent Libyan EFL postgraduate students adhere to the rules of etiquette in their formal emails. Another aim is to try to find out if there are any problems, they face in this respect in order to find better ways that may help in dealing with them. To fulfill these aims, 39 students were asked to send a formal email to their instructor (the researcher) of subjects of their own choice. However, only 34 emails were received. The results have shown that the majority of the students who have participated in the study are aware of the overall structure and organization of emails written in formal style. However, examining details have shown that students face some problems that are not only related to style, but also to language and culture. It was apparent from the emails investigated that students lack practice and experience in writing formal emails. To overcome these difficulties, teachers are advised to raise their students’ awareness of the importance of using formal emails as a means of communication and to provide them with sufficient practice by regularly using formal email in their correspondence with their teachers. Students also need to be aware of the inter-linguistic and cultural differences; what might be acceptable and favorable in Arabic may lead to miscommunication problems when used in English.

This coursebook is designed to satisfy the need for a coursebook that is suitable for the university level. It is a practical book which introduces syntactic concepts in a simple way and which gives a chance to students of syntax to understand these concepts through practice by doing related exercises. It is based on my experience of teaching syntax to university students for several years. 

The sequencing and the grading of material from simple topics to more difficult ones makes it easier to understand and grasp the ideas discussed. For example, Unit One is an introductory unit where syntax as a subject is clarified and where analysis approaches and methods of representations that will be used throughout the book are introduced and explained. Unit Two discusses the internal structure of clauses and phrases. It is only after a thorough understanding of these constituents has been ensured through illustrations and practice that the functions of these constituents are introduced in a separate unit, i.e. Unit three.