This work presents the use of laser diode in the fiber distributed data interface FDDI networks. FDDI uses optical fiber as a transmission media. This solves the problems resulted from the EMI, and noise. In addition it increases the security of transmission. A network with a ring topology consists of three computers was designed and implemented. The timed token protocol was used to achieve and control the process of communication over the ring. Nonreturn to zero inversion (NRZI) modulation was carried out as a part of the physical (PHY) sublayer. The optical system consists of a laser diode with wavelength of 820 nm and 2.5 mW maximum output power as a source, optical fiber as a channel, and positive intrinsic negative (PIN) photodiode with maximum responsivity at wavelength of 820 nm as a detector. Practical tests were carried out on the laser diode showed that the output characteristics and spectral characteristics of the laser diode depend largely on the drive current. The maximum separation distance between successive stations in the ring was 5.4 km. From the performance tests, it was concluded that the maximum throughput and maximum access delay are directly proportional to length of the transmitted information. A trade off between the transmitted information length and the maximum access delay is needed.
Abstract
The researcher seeks, through different aspects of the search, to reach a set of objective concerning in content creation a clear vision about conceptual and practical dimension of relation and effects between (Leader-Member Exchange, and Organizational Commitment) to construct a framework of a pragmatic model as a solution to research problem and it questions. The theoretical problem is derived basically from the scarcity of Arab studies and researches that deal by study and analyses for such important of The two variables blend. The practical problem depends in deriving from reality of every day work in the Iraqi ministry of defense.
On this basis, a formula of research problem for pur
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Premature degradation is the problem of maxillofacial silicones, significantly affected by ultraviolet exposure, contributing to silicones photodegradation. Degradation necessitates frequent replacement of prostheses that increase the total cost of rehabilitation.
This study evaluated the effect of bisoctrizole on the ultraviolet absorption properties of silicone material and the stability of this absorption over time. Also, the bisoctrizole effect on the surface roughness of silicone was evaluated.
Research Summary :
Praise be to God, Lord of the Worlds, and prayers and peace be upon the Master of the Messengers, his family and all his companions, then after:
This is brief research that contained between its two covers one of the jurisprudence rules derived from Islamic Sharia that guarantees the right of others, in case of forcing to do the prohibited act, and it is a restriction of the rule: “Necessities allow prohibitions” and “Hardship brings facilitation” and support for the rule: “Necessities are valued.” It is an origin in alleviating the taxpayer definitely , and the study has briefly shown some of the jurisprudential appli
... Show MoreThe present work aimed to make a comparative investigation between three different ionospheric models: IRI-2020, ASAPS and VOACAP. The purpose of the comparative study is to investigate the compatibility of predicting the Maximum Usable Frequency parameter (MUF) over mid-latitude region during the severe geomagnetic storm on 17 March 2015. Three stations distributed in the mid-latitudes were selected for study; these are (Athens (23.50o E, 38.00o N), Jeju (124.53o E, 33.6o N) and Pt. Arguello (239.50o W, 34.80o N). The daily MUF outcomes were calculated using the tested models for the three adopted sites, for a span of five-day (the day of the event and two days preceding and following the event day). The calculated datasets were co
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Pollutants generation is strongly dependant on the firing temperature and reaction rates of the gaseous reactants in the gas turbine combustion chamber. An experimental study is conducted on a two-shaft T200D micro-gas turbine engine in order to evaluate the impact of injecting ethanol directly into the compressor inlet air on the exhaust emissions. The study is carried out in constant speed and constant load engine tests. Generally, the results showed that when ethanol was added in a concentration of 20% by volume of fuel flow; NOx emission was reduced by the half, while CO and UHC emissions were almost doubled with respect to their levels when burning conventional LPG fuel alone.
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Background: Implant stability is a mandatory factor for dental implant (DI) osseointegration and long-term success. The aim of this study was to evaluate the effect of implant length, diameter, and recipient jaw on the pre- and post-functional loading stability. Materials and methods: This study included 17 healthy patients with an age range of 24-61 years. Twenty-two DI were inserted into healed extraction sockets to replace missing tooth/ teeth in premolar and molar regions in upper and lower jaws. Implant stability was measured for each implant and was recorded as implant stability quotient (ISQ) immediately (ISQ0), and at 8 (ISQ8) and 12 (ISQ12) weeks postoperatively, as well as post-functional loading (ISQPFL). The pattern of implant
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Background: Immediate implant placement in the maxillary anterior region was challenging, especially with the jumping gap and limited primary implant stability. Objective: To assess the autogenous dentin graft biomaterial's ability to improve the esthetic outcomes of an immediately inserted implant. Methods: Twenty patients with non-restorable retained roots in the maxillary non-molar region surrounded by natural sound teeth were included in this study after a complete clinical and radiological examination, including patient health and clinical fitness for the immediate dental implant procedure. A single dental implant was inserted for each patient, and the resulting jump distance was filled with the mineralized dentin graft and co
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