The wear modelling is of fundamental issue in the industrial field, mainly correlated to the economy and safety. Therefore, there is a need to study the wear models and wear estimation. This paper introduced the literature review for mechanical wear models. The function of wear models is to predict the rate of material removal from the surface. Classical wear theory begins by considering the rate of material removal as a function of some parameters such as load, sliding speed, sliding distance and hardness of material. In sliding wear models there are more than 100 different variables and constants. These models contains between two to twenty six variables in a single equation. Unfortunately, some constants are assigned to represent specific quantitative phenomena which are not readily measurable such as surface strength, and fatigue life of an asperity. Between 1957 and 1992, that there were 182 wear equations for the several types of wear. The most important issue of the 182 equations is that it include on a great number of variables. Each author combines a different array of variables, often for the same mechanical system.
WeDRisk is an approach designed to manage risks of web and distributed software development. The WeDRisk approach aims to address the weaknesses of existing approaches to risk management, which are less able to deal with the specific challenges of web and distributed development. A key part of the approach is flexibility, to deal with the rapid evolution which is typical of such developments. This paper presents the approach and describes the design, execution and analysis of a controlled experiment that has been used to evaluate some central parts of the approach, in terms of their usefulness, ease of understanding and usability. The paper focuses on the evaluation of estimation module part. Other parts will be introduced in next papers. The experiment result illustrated how the estimation module is useful, understandable, flexible easy to use, and considers web and distributed development risks factors.
Nafion ionomers with different Equivalent Weight (EW) 1000, and 1100 were incorporated with 4 mg/cm2 commercial Palladium supported carbonof a 30% Pd/C (ETEK) catalyst, in the Polymer Electrolyte Membrane(PEM) fuel cell catalyst layers and their effects on the catalyst layer optimization and performance were evaluated by measuring the PEM fuel cell i–V characteristics. The results showed that, for 4.0 ± 0.1 mg/cm2 of 30 % Pd/C loading, the optimum value Nafion ionomer percentage in the catalyst layer is 33 wt.% and this value is not change with the Nafion ionomer equivalent weight. Furthermore, it is possible to get high performance in PEM fuel cell under higher temperature (85 ̊C) by employing the ionomers with 1000 EW.
A variety of a non-linear complex system such as robotics and many other electrical systems require modeling and control. A direct adaptive control method is considered in this work for controlling of a DC motor system. The proposed direct adaptive control scheme is implemented in MATLAB and the simulated results show that the design requirements are achieved by using 10 radial basis functions with the optimum number of centres being determined by using K- means clustering algorithm. The optimum value for the learning factor is determined through simulation tests. Least mean square method is used to calculate the weight values for output layer for adaptive control scheme with radial basis function network. The direct adaptive control scheme provides a systematic approach for the automatic adjustment of controllers in real time, therefore, it can be used to maintain a desired level of control system performance when the system parameters are changing in time.
Nafion ionomer content in the PEM fuel cell catalyst layer is the most important parameter in designing high performance PEM fuel cell. In this study, different catalyst layers were prepared by mixing numerous Nafion ionomer (EW 1000) weight percentage (wt.%) ranging from 20 to 40 wt.% with 3.2 ± 0.1 mg/cm2 of palladium supported carbon ((30% Pd/C,) catalyst, and assembled with Nafion 1035 membrane to form membrane electrode assembly (MEA). The results showed that the best performance of the PEM fuel cell is obtained when 35 % of the Nafion ionomer is present in the catalyst layer. In addition, the microstructural study for the catalyst layers containing higher Nafion ionomer than 35 wt.% suggests that a very thin Nafion layer is produced on the outer surface of catalyst layer leads to blocking of the active sites of the palladium catalyst on the catalyst layer surface and decreased electrochemical reactions.
Despite the spread of smart learning systems in the field of training and education around the world, there are many great challenges in making these systems more effective, to provide an intelligent educational system in line with the standards of modern education. So there is a need to study the impact of the dissemination of smart learning methodology in the Libyan context. This study aimed to develop an intelligent learning system to assist trainees in QACC (Quality Assurance Certification Center) according to Fleming’s VAK Model (Visual , Auditory, and Kinesthetic),in the training course using Intelligent Learning System, from which these systems derive from the application of artificial intelligence techniques to educational systems, programs designed to simulate the behavior of trainees and the preferred learning method, they are able to explain the trainees' behavior and preferred learning style so that the system can capture patterns Learning and cognitive skills of trainees, and able to interpret the responses of complex trainees. The main purpose is to compare the effects of two different methods of training (VAK training, traditional classroom training) on trainees' achievement. The study was conducted on a sample of 46 trainees, divided into two groups. The first group contains (23) trainees in the maintenance course using the traditional learning method. The second group contains (23) trainees who use intelligent learning technique and do the questionnaire before the trial begins. The results of the study showed that the intelligent learning group's the academic achievement that use the VAK model is higher than the traditional learning group, and noted that the results also indicated that there are statistical differences (α ≤0.05) for the learning types of trainees at QACC in both (VAK, traditional training ).
In recent years programming languages have been included in the curriculum for Libya’s secondary schools. It is one of the basic skills taught to computing students and visual basic is one of the tools applied when the students are unfamiliar with programming languages. Often students experience difficulty in terms of understanding and then executing certain programs, and the program procedures to show the results. With the growth in software reverse engineering where the practice of analysing a software system help to extract design and implementation information. We present a new tool named VB2ALGO that generates an algorithm (a flow chart and pseudo code) of the source code of Visual Basic program to help students and teachers using this algorithm to understand the program or to build the same program in other languages.