This paper deals with the modeling of a preventive maintenance strategy applied to a single-unit system subject to random failures.

According to this policy, the system is subjected to imperfect periodic preventive maintenance restoring it to ‘as good as new’ with probability

p and leaving it at state ‘as bad as old’ with probability q. Imperfect repairs are performed following failures occurring between consecutive

preventive maintenance actions, i.e the times between failures follow a decreasing quasi-renewal process with parameter a. Considering the

average durations of the preventive and corrective maintenance actions a

لابد لكل باحث في أي موضوع يرغب في عن القارة الافريقية  والمناطق المسلمة منها بشكل خاص ان يتلمس طرق حريتها وتحريرها وانعتاقها علية التحري والبحث عن العقدة الدينية التي عتنقها اهلها والتي جعلت منهم تواقين الى الحرية واثر هذة العقدة على ذلك الانسان في التحرير من كل اشكال العبودية

The seed propagation is the predominant method of Echinacea propagation, which has been criticized for its time-consuming control over the separation factor and the uncertainty of pathogen-free plants produced by this method. The technology of tissue culture has provided multiple opportunities for the production of secondary metabolites continuously without being restricted to a specific season, due to the possibility of controlling the environmental conditions and the components of the nutrient medium needed by the plant. This study was conducted to investigate the effects of salicylic acid as elicitor and tyrosine as precursor on propagation and some secondary compounds production in coneflower in vitro. The result showed the superiori

 مشكلة البحث:

تعد مناهج كليات التربية العمود الفقري لإعداد مدرسين تربويين تقع على عاتقهم مهمة تربية وتعليم الجيل الذي سيتحمل مسؤولية بناء المجتمع وتطويره من خلال بناء وإعداد الأفراد في العديد من المجالات. ولما كان التغيير والتطوير المستمرين هما من السمات المميزة للعصر الذي نعيش فيه لذا تتطلب العملية التربوية مراجعة مستمرة لمناهجها بغية تقويمها وتطويرها بما يتناسب ومت

It highlights the importance of construction projects because of its significant role in the development of society, including the buildings FEDE projects to their importance to raise the level of education through the conclusion of the special to implementation and the establishment of schools of contracts at the country level, which requires the completion of the project at less time and within the cost specified and the best quality and may highlight the importance of time on all the elements of what has an important role in setting up the project for various reasons may be the need for the use of schools as soon as possible, but the reality showed exceeded the completion of those schools could be up to 6 years and there are some cont

In the present study, the growth and total lipid contents of two oleaginous fungal isolates Aspergillus terreus, Aspergillus fumigatus were compared in different nitrogen and organic carbon sources.  Artificially the fungi were cultured on media consisting of various mono- or di- or polysaccharides and  peptone or yeast extract as elementary sources for carbon and nitrogen, respectively. Media containing sucrose /yeast extract or glucose/ yeast extract were the most effective for lipid production from fungal, during  two weeks  incubation period, the highest biomass of dry weight was (19.6 , 18.8) g / L , (25.8 , 30.5) g /L  and  lipid yield (1, 0.97 )g/L, (0.65, 0.65) g/ L for two isolates Aspergillus terreus

The study aimed to examine the impact of audit committee characteristics on the practices of intellectual capital disclosure in the annual reports of Bank and Insurance companies listed on Palestine Exchange, through performing content analysis of the annual reports for the study sample which totaled thirteen companies, including six banks and seven insurance companies. To achieve the study objectives, the study employed a content analysis approach in order to analyze the content of the intellectual capital disclosure practice, in addition, the study used cross-sectional with longitudinal data for time series for a period of time between 2014-2019. The empirical results indicated that financial expertise and the number of meeting

This study aimed to improve the microencapsulation technique using a type coating the encapsulation Layer by Layer, which provide the best protection for life Lactobacillus casei in the extrusion method and use the microencapsulation of materials of the protein concentrated by protein 80% and the coating with alginate and chitosan have the results showed the variation in the difference of the binding process encapsulation yield among the types of coating through. by studying of these the effect o stability of the bio probiotic free cell and the three types coated towards three different concentrations from bile salts 0, 0.3, 0.5 and 0.7% when the periods of time different of zero and two and three hours at incubation the recorded

This study aims at identifying the extent of SMS usage and understanding the role it plays in satisfying users' needs and motivations. In order to achieve this aim, an analytical descriptive method was adopted by conducting a field survey among students at Petra University.

The study resulted in many conclusions, the most important of which is that using SMS meets the students' cognitive, social and communicational needs and desires, the highest being communicating with friends at 75%, followed by exchanging songs and videos at 52%, as well as exchanging photos at 45%. In regards to their motivation for using text messaging, forgetting daily problems scored highest at 81.4% and spending free time followed at 77.4%. This proves th

Means of communication has a great impact on all fields of awareness including health awareness by increasing the knowledge of community about health and developing their abilities to improve human health and cultural awareness. According to the importance of health awareness for a community to develop their intellectual and physical integrity, the researcher has found that it is essential to know the role of means of communication as a source of information for many students being active and main segments to build their society intellectually, socially and economically.

The research has focused on the study of health awareness among students and their health knowledge derived from the means of communicat