Recent advances in wireless communication systems have made use of OFDM technique to achieve high data rate transmission. The sensitivity to frequency offset between the carrier frequencies of the transmitter and the receiver is one of the major problems in OFDM systems. This frequency offset introduces inter-carrier interference in the OFDM symbol and then the BER performance reduced. In this paper a Multi-Orthogonal-Band MOB-OFDM system based on the Discrete Hartley Transform (DHT) is proposed to improve the BER performance. The OFDM spectrum is divided into equal sub-bands and the data is divided between these bands to form a local OFDM symbol in each sub-band using DHT. The global OFDM symbol is formed from all sub-bands together using the (IDHT). The BER performance of the proposed system is simulated and compared with the conventional OFDM in different channel conditions to show the gain in SNR achieved by the proposed system.
Nonlinear time series analysis is one of the most complex problems ; especially the nonlinear autoregressive with exogenous variable (NARX) .Then ; the problem of model identification and the correct orders determination considered the most important problem in the analysis of time series . In this paper , we proposed splines estimation method for model identification , then we used three criterions for the correct orders determination. Where ; proposed method used to estimate the additive splines for model identification , And the rank determination depends on the additive property to avoid the problem of curse dimensionally . The proposed method is one of the nonparametric methods , and the simulation results give a
... Show MoreThe study conducted on the compositions of epiphytic diatoms on three taxa of aquatic plants were selected (Phragmites australis Trin ex stand , Ceratophyllum demersum L. and Typha domengensis Pers) in three sites within Al-Auda Marsh, from autumn 2013 to summer 2014 . The study was measured physical and chemical factors of all the study sites, such as: air temperature, power of hydrogen (pH), electrical conductivity (EC), salinity (S‰), total hardness(TH), dissolved oxygen (DO), and plant nutrient. The results showed that water of marsh was oxygenated and it was very hard. A total of 111 taxa of phytoplankton were identified, which belonged to 13 families and 26 genus (one family and two genus of centric diatoms, 12 families and 26 ge
... Show MoreBackground:sThe aims of this study were to evaluate and compare the ability of three different techniques to obdurate simulated lateral canals, evaluate the effect of the main canal curvature on obturation of lateral canals and compare the gutta-percha penetration between coronal and apical lateral canals. Materials and methods: Resin blocks with 30 straight and 30 curved were used in this study. Each canal has two parallel lateral canals. The main canal has 0.3 mm apical diameter and 0.04 taper. The canals were divided into six groups according to canal curvature and obturation techniques used (n=10): Groups C1 and C2: straight and curved canals obturated with continuous wave technique using E&Q masterTM system. Groups O1 and O2: straight
... Show MoreOne male specimen of the species Metapenaeus stebbingi Nobili, 1904 was first recorded in November 2021 from the Iraqi territorial waters, Northwest of the Arabian Gulf. Therefore, the investigated shrimp species nominally corresponds to the original description of M. stebbing through the main diagnostic features. It must be adopted in the spread and expansion of species, a new record of the area, and a distinctive addition to the species of commercial shrimp within the Iraqi marine waters.
Geophysics is one of the branches of Earth sciences and deals with studying the Earth's interior by studying the variation of physical properties within rock layers. Applied geophysics depends on procedures that involve the measurements of potential fields, such as the gravitational method. One of the significant oil fields in southern Iraq is represented by the Nahr Omar structure. A power spectrum analysis (SPA) technique was used to collect gravity data within the chosen oil field area in order to confirm the salt dome in the subsurface layers. The analysis of SPA resulted from six surfaces representing the gravity variation values of the depths (m)14300, 3780, 3290, 2170, 810, and 93.5. Gravity surfaces have been converted to de
... Show MoreThe relative strength index (RSI) is one of the best known technical analysis indicators; it provides the speculators by prior signals about the future stock’s prices, and because the speculations in shares of companies which listed in the Iraq Stock Exchange have a high degree of risk, like risk of shares prices felling, so the speculators became committed to use some methods to reduce these risks, and one of these methods is the technical analysis by using the relative strength index (RSI) which enable the speculators of choosing the right time for buy and sell the stocks and the right time to enter or leave the market by using the historical rice data. And from here the problem of the research formulated as “Is the using of
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