Abstract In spite of their widely-spread use across the globe, the domestic solar water heaters are still subject to essential, technical difficulties that need to be deeply studied. Such technical impediments are latent in how appropriate to each other the different, mutually-dependent components of the system are; and how appropriate they are to the prevailing meteorological conditions of the application site which is still under research and development. This thesis presents a clear-cut, straightforward mathematical model that determines the basic factors influencing such systems, and, in specific, discusses the optimum design month as well as the optimum tilt angle of the solar collector, bearing in mind the contribution of the energy obtained to meet the targeted load. Furthermore, the study considers the required thermal capacity that should be provided by the solar collector. To avoid assumptions that could be unjustified in practice, and to get as precise results as possible, the study was thoroughly based on normalized mathematical parameters. In the case where the total demand for energy used in water heating is to be fully satisfied by the solar energy system, provided that the required temperature of the heated water is 45oC and consumption is 100 (litre/day) per person for a given house, the results of the study concluded that according to the climate information of Tripoli city, 32.68°N latitude, the optimum design month is December, the optimum tilt angle is 75°, and the solar collector area fulfilling the following specifications: Glazed type, Fr () = 0.58, and Fr UL= 4.00 (W/m2oC) is 2.83 square meters. On the other hand, the results suggest an optimum tilt angle of 50°, which is the same angle obtained by the traditional technique, and solar collector area of 1.6 square meters if up to 80% of demand is to be covered by solar energy.
علاء بلقاسم العلوني (2010)

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)

Abstract The contribution of this thesis is to improve the understanding of acoustic dynamics in the audio duct with Helmholtz Resonator (HR). In this project, detail measurements of acoustic in a duct with HR induced loud–speaker at various frequencies have been carried out experimentally. Two-microphone technique have been used to measure the net acoustic power transmission in the duct downstream of HR along with the net acoustic power transmission in the duct without the HR. The acoustic wave signals are traveling in the duct as a plane wave, these waves are generated by a signal generator system with a know wave (sine wave). One of the microphone is located just before the neck–duct interface and the other microphone after the HR in the duct. Five type of necks ( perforated neck length 15cm, perforated neck length 10cm, cone–shape neck, Non- perforated neck length 15cm, Non-perforated neck length 10cm ) and three different material of the bottom wall of the cavity ( Teflon, water and cotton ) have been studied. The best results has a good advantage that by using (perforated neck length 15 cm and 4cm diameter because that reduction of noise has been reached 64% percentage and that value is the highest reduction from all experimenting.
إبراهيم فاضل عبد الحميد الزوي (2010)