Digital Repository for University of Tripoli

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)

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)

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)

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)

All -ceramic restorations are nowadays widely accepted in the anterior and posterior regions. The geometry of tooth preparation has been the subject of many debates without clear evidence that one type of finish line provides consistently superior marginal fit. Therefore, the main interest of the present research was directed toward the influence of margin configuration on marginal adaptation of all ceramic crowns. Articles were selected on the basis of they had sufficient information related to types of the finish line and related factors effect on marginal adaptation of all ceramic crowns. The results of this study revealed that the best finish line chose for all ceramic restorations still remains a difficult goal to be achieved. arabic 14 English 84
Seham Ali Elsawaay*, Milad Mustafa Eshah, Mohamed Albasher Zeglam(1-2019)

The aim of the present study was to evaluate abutments of crowns and conventional fixed dental prosthesis in terms of complying Ante’s law, and periapical lesions through a retrospective analysis of orthopantomographs (OPTGs) of patients in private dental clinic. In this study, the digital OPTGs of adult patients between the ages of 30 and 75 who appealed to private dental clinic for the first time to have their fixed prosthetic treatment needs met were used. The routine dental radiographs were taken in the first appointment of the patients. The periapical health of all teeth restored with crowns and bridges were evaluated by radiographic criteria according to periapical index (PAI). The present study comprised panoramic radiographs belongs to43 women and 27 men with an age range of 30 to 75 years old. No relationship was observed between gender and periapical lesion. While the amount of fixed prosthesis was highest in the lower jaw with 54%. The most commonly used abutment tooth were premolar teeth.36% of bridges didn’t meet the requirements of Ante’s law. More periapical lesion were observed among the restorations which doesn’t meet the requirements of Ante’s law. According to the results of the present study, the restoring of missing teeth with FPDs may cause different periapical pathologies. Optimum evaluation of abutments regarding to Ante’s law and periapical status may decrease the complications that could be observed in long term prognosis of FPDs arabic 11 English 76
Seham A. Elsawaay, Enas A.Khamakhim(5-2019)

The aim of this in vitro study is to compare the shear bond and bi-axial flexural strengths of samples veneered with, CAD/CAM-fabricated zirconia core, and Press-on technique, with the definition its mode of failure. Twenty zirconia core discs were made using IPs e.max ZirCAD and CAD/CAM technology. These were divided equally in to two groups. Group one was veneered by CAD-on technique using IPs e.max CAD, and group two was veneered by Press-on technique using IPs e.max ZirPress, then all the discs are thermocycled. The specimens were exposed to shear bond and biaxial flexural strength testing. Mode of failure was evaluated by SEM. All data were collected and analyzed statistically by SPSS, with significance level 5%, where P≤ 0.05. The t- test analysis of shear strength test showed statistically significant difference at (p < 0.05) for CAD-on group. While there were no statistically significant difference at (p < 0.05) for the biaxial flexural strength test between the two groups. CAD-on group showed adhesive/cohesive failure, while press-on group showed cohesive failure within the veneering ceramic. This study concluded that, the bond strength between zirconia core and veneer was affected by the veneering technique. CAD-on technique showed statistically significant high bond strength over Press-on technique arabic 20 English 98
Seham Ali Elsawaay*, Milad Mustafa Eshah, Mohamed Al basher Zeglam(1-2018)

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)