Passive optical network (PON) is a point to multipoint, bidirectional, high rate optical network for data communication. Different standards of PONs are being implemented, first of all PON was ATM PON (APON) which evolved in Broadband PON (BPON). The two major types are Ethernet PON (EPON) and Gigabit passive optical network (GPON). PON with these different standards is called xPON. To have an efficient performance for the last two standards of PON, some important issues will considered. In our work we will integrate a network with different queuing models such M/M/1 and M/M/m model. After analyzing IPACT as a DBA scheme for this integrated network, we modulate cycle time, traffic load, throughput, utilization and overall delay mathematically for single OLT and multiOLT EPON system, and average delay and throughput for single OLT GPON system. A comparison of average delay and throughput between EPON and GPON is introduced with the same number of ONUs. The results show that the proposed multi-OLT EPON system can supports existing bandwidth allocation schemes with better performance than the single-OLT EPON. Cycle delay and average delay is decreased with multi-OLT system than in single OLT system, while throughput of multi-OLT system is higher than throughput of single OLT system. Splitting ratio and throughput in GPON is much higher than in EPON.
This paper shows that there are few studies on errors and difficulties with unstressed pronouns in Spanish. Similarly, when consulting teaching methods, we find that the most consulted texts are ELE manuals. In this sense, the purpose of this paper is to verify the teaching proposal regarding unstressed pronouns in the ELE manuals most used at the Faculty of Languages - University of Baghdad, Iraq. It is urgently needed for ELE teachers in Iraq and students to obtain the most recent ELE manuals, as this will help them teach and learn about unstressed pronouns with texts that contain more didactic and engaging exercises. Furthermore, teachers will be able to plan strategies and lessons for the correct use of these texts.
Mycobacterium tuberculosis resistance to rifampicin is mainly mediated through mutations in the rpoB gene. The effects of rpoB mutations are relieved by secondary mutations in rpoA or rpoC genes. This study aims to identify mutations in rpoB, rpoA, and rpoC genes of Mycobacterium tuberculosis isolates and clarify their contribution to rifampicin resistance. Seventy isolates were identified by acid-fast bacilli smear, Genexpert assay, and growth on Lowenstein Jensen medium. Drug susceptibility, testing was performed by the proportional method. DNA extraction, PCR, and sequencing were accomplished for the entire rpoA, rpoB, and
... Show MoreThe structure and composition of the stellar population in the surface brightness galaxy Ic 467 is studied using BVR CCD photometry. The observations were obtained on the 1.88m optical telescope of Kottamia Astronomical Observatory, KAO, Egypt. A two-dimensional decomposition of the galaxy bulge and disk components is carried out. A powerful star forming region is observed near the galactic center. Based on the positions of the various components of the galaxy in two color diagrams and the surface brightness of the eastern arms in V filter is brighter than the western arm. From the observations, the surface brightness profiles, Ellipticity profiles, position angle profiles and color indices profiles are described and studied.
The present study has three objectives: 1) to investigate the prevalence of complex nominals in economic discourse represented via the selected business news texts, 2) to shed some light on the most common translation errors made by second year students in the Department of Translation in rendering complex nominals into Arabic, and 3) to detect the possible causes behind such translation errors and suggest some translation tips which might sound helpful to the students of translation to find the most suitable translation equivalent. The present study is based on an empirical survey in which a selective analysis of someeconomic texts represented in business news texts is made. A corpus of 159 complex nominals was selected from seven busin
... Show MoreThis study attempts to provide an approach analysis for the news, depending on the bases and principles which conceptuality semiotic researchers of this field first of them «A. J. Gremas» for the theory of «narrative discourse analysis», to more clarify we tried to apply it on a published press- news, to concludes the most important steps and methods that are necessary to follows gain more understanding of the press- news.
The response of floating stone columns of different lengths to diameter ratio (L/D = 0, 2, 4, 6, 8, and 10) ratios exposed to earthquake excitations is well modeled in this paper. Such stone column behavior is essential in the case of lateral displacement under an earthquake through the soft clay soil. ABAQUS software was used to simulate the behavior of stone columns in soft clayey soil using an axisymmetric finite element model. The behavior of stone column material has been modeled with a Drucker-Prager model. The soft soil material was modeled by the Mohr-Coulomb failure criterion assuming an elastic-perfectly plastic behavior. The floating stone columns were subjected to the El Centro earthquake, which had a magnitude of 7.1 an
... Show MoreWriting plays an effective role in developing one's thinking and
enhancing Learning. It is, in fact, a means of widening one's own views about
the world for the numerous uses that it can serve (Samuel, 1988:28).
In regard to the unquestionable significance of writing in the teaching –
Learning process, the traditional approach seems to be far from being able to
put such significance into practice. Traditionalists give priority to formulating
students' ideas before using prescribed rhetorical framework and then
submitting the written product for grading. Emphasis is, therefore, limited to the
prewriting stage where a certain topic is explored, and the role of the teacher is
confined to assigning the topic and