المنشورات العلمية لـكلية الهندسة

احصائيات منشورات كلية الهندسة

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    وثيقة

Effects of Design Parameters of Wind Turbine on Airfoil Coefficients Using Grey-Based Taguchi Method

Abstract— Horizontal-Axis Wind Turbine (HAWT) small scaled is widely employed for generating electricity for domestic uses due to higher efficiencies among other turbines. Three-Blade HAWTs power performance can be further improved by optimizing lift (CL), drag (CD) coefficients and thus power (CP) coefficient. In this study, Taguchi design of experiments (DOE) of L9 orthogonal array (OA) with three parameters and one interaction, namely airfoil, angle of attack, interaction (between the airfoil and the attack angle), and Reynolds number with three value levels are used to determine the single quality (CL, CD, CP) optimization. For multi-qualities optimization, the Grey-based Taguchi is employed which combines the Taguchi DOE orthogonal array with grey relational analysis to determine the grey relational grade, which can convert the multi-response grey relational grade into single grey relational grade, thus the optimal design parameters can be achieved. The Q-Blade software is used to determine lift and drag coefficients and empirical equation used for power coefficient. The obtained results show that the most influence design parameter on airfoil coefficients is Reynolds number with 72.6% contribution followed by attack angle with 16.8%, interaction with 9.1% and airfoil with 1.5%. The F-value indicates that Reynolds number and angle of attack give at least 97.5% and 90% confidence respectively, for this specific set of experiments. arabic 14 English 86
Abdulhamed M. Hwas, Ali M. Hatab(12-2020)
موقع المنشور

The Current Awareness of Just-In-Time Techniques within the Libyan Textile Private Industry: A Case Study

Almost all Libyan industries (both private and public) have struggled with many difficulties during the past three decades due to many problems. These problems have created a strongly negative impact on the productivity and utilization of many companies within Libya. This paper studies the current awareness and implementation levels of Just-In-Time (JIT) within the Libyan Textile private industry. A survey has been applied in this study using an intensive detailed questionnaire. Based on the analysis of the survey responses, the results show that the management body within the surveyed companies has a modest strategy towards most of the areas that are considered as being very crucial in any successful implementation of JIT. The results also show a variation within the implementation levels of the JIT elements as these varies between Low and Acceptable levels. The paper has also identified limitations within the investigated areas within this industry, and has pointed to areas where senior managers within the Libyan textile industry should take immediate actions in order to achieve effective implementation of JIT within their companies. arabic 17 English 88
ٌRajab HOKOMA(7-2010)
عرض موقع المنشور

Just-In-Time for Reducing Inventory Costs throughout a Supply Chain: A Case Study

Supply Chain Management (SCM) is the integration between manufacturer, transporter and customer in order to form one seamless chain that allows smooth flow of raw materials, information and products throughout the entire network that help in minimizing all related efforts and costs. The main objective of this paper is to develop a model that can accept a specified number of spare-parts within the supply chain, simulating its inventory operations throughout all stages in order to minimize the inventory holding costs, base-stock, safety-stock, and to find the optimum quantity of inventory levels, thereby suggesting a way forward to adapt some factors of Just-In-Time to minimizing the inventory costs throughout the entire supply chain. The model has been developed using Micro- Soft Excel & Visual Basic in order to study inventory allocations in any network of the supply chain. The application and reproducibility of this model were tested by comparing the actual system that was implemented in the case study with the results of the developed model. The findings showed that the total inventory costs of the developed model are about 50% less than the actual costs of the inventory items within the case study. arabic 14 English 67
Rajab HOKOMA, Faraj Farhat El Dabee(9-2012)
عرض موقع المنشور

The Effect of Fuel Additives on Spark Ignition, and Their Implications on Engine Performance: An Experimental Study

This paper is designed to present an experimental study being recently conducted for investigating the effect of some fuel additives on the performance of spark ignition within a benzene engine. Three types of additives were added separately (Gasoline Additive, Gasoline Booster, and Octane Booster) to pure gasoline with a volumetric ratio 1:6, 1:7, and 1:8 respectively. Four separate laboratory experiments being conducted using an internal combustion engine at rotational speed ranges from 600 to 3000 rpm, where the three mixtures and the pure gasoline itself were used. The findings showed that there was a positive effect on the engine performance as the brake power increases by 8%, 13% and 23% at the use of Gasoline Additive, Gasoline Booster, and Octane Booster respectively as compared with using only the pure gasoline. The brake thermal efficiency (ɳth) was also affected positively showing its maximum value of about 8% for Octane Booster, and with a minimum value for using Gasoline Additive at about 4.7%. In addition, this study showed that the value changes in the brake specific fuel consumption for Gasoline Additive, Gasoline Booster, and Octane Booster was at the levels of 1%, 2%, and 5% respectively compared with using only the pure gasoline. Furthermore, the results also showed that the use of Octane Booster gave the highest level of air fuel ratio arabic 18 English 97
ٌRajab HOKOMA, Nabil M. Muhaisen(1-2017)
عرض موقع المنشور

Just-In-Time Implementation Status Within Libyan Cement Industry (A Case Study)

This paper investigated the implementation status of Just-In-Time practices within the Libyan cement industry. The required data/information were gathered from the target factories through interviewing the most involved people in the decision making process within this business area, and through a questionnaire, developed for this survey in order to identify the actual application levels for the key-factors being considered as the most crucial for any successful and effective application. The findings showed that the cement industry suffers from many problems in managerial, manufacturing, and industrial operations. Among of them are lack of clear policies and strategic plans. Based on the findings, the paper recommended that the management body should pay more attention for providing all the requirements to qualify and train the related employees and personnel, providing the spare parts required for maintenance programs, and do not neglect the security aspect, and should focus on the safety issues within the work-place. The paper also suggested that clear policies and strategies should be well-formulated, adapting modern technologies and techniques for maximizing the efficiency and effectiveness throughout the cement industrial operations arabic 13 English 66
ٌRajab HOKOMA, Hala Mansour Amaigl(7-2018)
عرض موقع المنشور

A Survey Investigation of Just-in-Time Implementation and its Implications for Management in Four key Industries within Libya

This paper investigates the current status of the implementation level of Just-In-Time (JIT) within the Oil & Gas (OGI), Iron & Steel (ISI), Cement (CI) and Construction (C) Industries within Libya and its implication for management within the said industries. A survey methodology has been applied in this investigation using an intensive questionnaire and one-to-one interviews of the correspondent organizations. Based on the analysis of the survey questionnaire and the one-to-one interview responses, the results show that the management body does not have a clear strategy towards most of the areas that are considered as being crucial in any successful implementation of the JIT techniques. The implementation levels of the JIT techniques are found to be in the modest levels even in the organizations that have indicated themselves as JIT implementers. The research has identified management limitations within the investigated areas and has pointed to areas where the management body needs to take immediate actions in order to achieve an effective and successful JIT implementation within their organizations. This is an important finding for the future success of the Libyan industries and the similar ones. arabic 18 English 107
ٌRajab HOKOMA(1-2016)
عرض موقع المنشور

Repeated Projectile Impact Tests on Multi-Layered Fibrous Cementitious Composite

This research aims to experimentally evaluate the behaviour of multi-layered fibrous cementitious composites with intermediate Glass Fibre Meshes (GFM) under repeated projectile load. The impact load was subjected through a convex edge projectile needle at a low velocity on cylindrical specimens of three-layered fibrous cementitious composites, which have two different steel fibre distributions. In series A mixtures, a constant steel fibre dosage of 2.5% by volume was used. On the other hand, the fibre dosage of the outer layers was 3.0%; while it was 1.5% in the middle layer of series B mixtures. The number of intermediate GFM was the variable that distinguishes the mixtures of each series. The resistance to projectile impacts was evaluated on the basis of penetration depth, near surface distortion, weight loss, damage ratio and failure pattern. The test results showed that due to the combined effect of steel fibre and GFM, significantly lower weight losses were recorded for series A and B specimens compared with reference specimens. However, the different fibre distributions (series B) led to lower penetration depths and weight losses with less surface distortion compared with the fixed fibre distribution (series A). The reduction in the destroyed front surface area of series A specimens compared with reference specimens ranged from 27.8 to 38.1%; while that of series B specimens ranged from 34.8 to 53.4%. In addition, a simplified analytical model was introduced to predict the ejected composite mass. The model predictions were found to be in good agreement with the experimental masses. arabic 9 English 71
Hakim S. Abdelgader (1-2021)
موقع المنشور

Palm Oil Fuel Ash-Based Eco-Efficient Concrete: A Critical Review of the Short-Term Properties

The huge demand for concrete is predicted to upsurge due to rapid construction devel- opments. Environmental worries regarding the large amounts of carbon dioxide emanations from cement production have resulted in new ideas to develop supplemental cementing materials, aiming to decrease the cement volume required for making concrete. Palm-oil-fuel-ash (POFA) is an indus- trial byproduct derived from palm oil waste’s incineration in power plants’ electricity generation. POFA has high pozzolanic characteristics. It is highly reactive and exhibits satisfactory micro-filling ability and unique properties. POFA is commonly used as a partially-alternated binder to Portland cement materials to make POFA-based eco-efficient concrete to build building using a green material. This paper presents a review of the material source, chemical composition, clean production and short-term properties of POFA. A review of related literature provides comprehensive insights into the potential application of POFA-based eco-efficient concrete in the construction industry today. arabic 16 English 78
Hakim S. Abdelgader , (1-2021)
موقع المنشور