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Performance evaluation of frequency division duplex (FDD) massive multiple input multiple output (MIMO) under different correlation models
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Massive multiple-input multiple-output (massive-MIMO) is considered as the key technology to meet the huge demands of data rates in the future wireless communications networks. However, for massive-MIMO systems to realize their maximum potential gain, sufficiently accurate downlink (DL) channel state information (CSI) with low overhead to meet the short coherence time (CT) is required. Therefore, this article aims to overcome the technical challenge of DL CSI estimation in a frequency-division-duplex (FDD) massive-MIMO with short CT considering five different physical correlation models. To this end, the statistical structure of the massive-MIMO channel, which is captured by the physical correlation is exploited to find sufficiently accurate DL CSI estimation. Specifically, to reduce the DL CSI estimation overhead, the training sequence is designed based on the eigenvectors of the transmit correlation matrix. To this end, the achievable sum rate (ASR) maximization and the mean square error (MSE) of CSI estimation with short CT are investigated using the proposed training sequence design. Furthermore, this article examines the effect of channel hardening in an FDD massive-MIMO system. The results demonstrate that in high correlation scenarios, a large loss in channel hardening is obtained. The results reveal that increasing the correlation level reduces the MSE but does not increase the ASR. However, exploiting the spatial correction structure is still very essential for the FDD massive-MIMO systems under limited CT. This finding holds for all the physical correlation models considered.

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Publication Date
Thu Dec 01 2022
Journal Name
Journal Of Engineering
Evaluation of the Influence of De-sanding (Recycling System) Process on the Pile Bearing Capacity Using Full Scale Models
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The present study investigates the effect of the de-sanding (recycling system) on the bearing capacity of the bored piles. Full-scale models were conducted on two groups of piles, the first group was implemented without using this system, and the second group was implemented using the recycling system. All piles were tested by static load test, considering the time factor for which the piles were implemented. The test results indicated a significant and clear difference in the bearing capacity of the piles when using this system. The use of the recycling system led to a significant increase in the bearing capacity of the piles by 50% or more. Thus it was possible to reduce the pile length by (15 % or more) thus, and implementation costs

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Publication Date
Thu Dec 01 2022
Journal Name
Journal Of Engineering
Evaluation of the Influence of De-sanding (Recycling System) Process on the Pile Bearing Capacity Using Full Scale Models
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The present study investigates the effect of the de-sanding (recycling system) on the bearing capacity of the bored piles. Full-scale models were conducted on two groups of piles, the first group was implemented without using this system, and the second group was implemented using the recycling system. All piles were tested by static load test, considering the time factor for which the piles were implemented. The test results indicated a significant and clear difference in the bearing capacity of the piles when using this system. The use of the recycling system led to a significant increase in the bearing capacity of the piles by 50% or more. Thus it was possible to reduce the pile length by (15 % or more) thus, and implementation c

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Publication Date
Sat Feb 01 2020
Journal Name
Journal Of Economics And Administrative Sciences
Applying some hybrid models for modeling bivariate time series assuming different distributions for random error with a practical application
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Abstract

  Bivariate time series modeling and forecasting have become a promising field of applied studies in recent times. For this purpose, the Linear Autoregressive Moving Average with exogenous variable ARMAX model is the most widely used technique over the past few years in modeling and forecasting this type of data. The most important assumptions of this model are linearity and homogenous for random error variance of the appropriate model. In practice, these two assumptions are often violated, so the Generalized Autoregressive Conditional Heteroscedasticity (ARCH) and (GARCH) with exogenous varia

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Publication Date
Tue Aug 15 2023
Journal Name
Bionatura
Gene expression of a nitrogen tolerance gene ZmNR1 under the influence of different levels of nitrogen in maize
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A field experiment was carried out in the College of Agricultural Engineering Sciences - University of Baghdad, during the fall season of 2021 to find out which cultivated cultivars of maize are efficient under nitrogen fertilization. The experiment was applied according to an RCBD (split-plot design with three replications). The cultivars of the experiment (Baghdad, 5018, Sarah) supply three levels of nitrogen fertilizer, which are N1 (100 kg.N/ha), N2 (200 kg.N/ha) and N3 (300 kg.N/ha). The statistical analysis results showed the superiority of the Sarah genotype, which gave the highest value of SOD and CAT enzymes, reaching 11.59 units mg-1 and 10.76 units mg-1 . Protein sequentially, while cultivar5018 outperformed as it gave th

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Publication Date
Sun Sep 07 2008
Journal Name
Baghdad Science Journal
Proparyation of Low frequency microwave in dusty Plasma
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The numerical simulation for the low frequency waves in dusty plasma has been studied. The studying was done by taking two special cases depending on the direction of the propagation of the wave:First, when the propagation is parallel to the magnetic field K//B,this mode is called acoustic mode.Second,when K B this mode is called cyclotron mode.In addition, every one of the two modes divided into two modes depending on the range of the frequency.The Coulomb coupling parameter was studied, with temperature T,density of the dust particles Nd ,and the charge of the particle Qd.The low frequency electrostatic waves in dusty grains were studied. Also, the properties of ion-acoustic waves and ion-cyclotron waves are shown to modify even through

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Publication Date
Sun Dec 01 2019
Journal Name
Al-khwarizmi Engineering Journal
Effects of Sodium Chloride and Sodium Sulphate Solutions on the Output of the Electrochemical Machining
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Electrochemical Machining is a term given to one of nontraditional machining that uses a chemical reaction associated with electric current to remove the material. The process is depending on the principle of anodic dissolution theory for evaluating material removal during electrochemical process. In this study, the electrochemical machining was used to remove 1 mm from the length of the a workpiece (stainless steel 316 H) by immersing it in to electrolyte (10, 20 and 30 g) of NaCl and Na2SO4 to every (1 litter of filtered water).  The tool used was made from copper. Gap size between the workpiece and electrode is (0.5) mm. This study focuses on the effect of the changing the type and concentration of electroly

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Publication Date
Tue Jun 02 2026
Journal Name
Medicine And Health Sciences
Performance Evaluation of TB-LAMP in the Diagnosis of Pulmonary Tuberculosis
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Background: Tuberculosis (TB), caused by Mycobacterium tuberculosis (MTB), is one of the most common infectious diseases, especially in countries with limited healthcare resources. Early and accurate diagnosis is essential to curb its spread, and loop-mediated isothermal amplification (LAMP) is a rapid, cost-effective, and reliable molecular diagnostic method. Objective: The objective of this study was to evaluate the performance of TB-LAMP as a rapid and reliable diagnostic tool for pulmonary TB and compare it with direct smears and Gene Xpert, using culture as a reference. Materials: Between February and July 2025, a total of 397

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Publication Date
Wed Aug 21 2019
Journal Name
International Journal On Advanced Science, Engineering And Information Technology
Evaluation of the Performance of Glasphalt Concrete Mixtures for Binder Course
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Publication Date
Tue Aug 01 2023
Journal Name
Iop Conference Series: Earth And Environmental Science
Evaluation of the Performance of a Locally Manufactured Palm Service Platform
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Abstract<p>A field experiment was carried out in one of the orchards of Al-Qassim district in Babel Governorate to find out the ability of a locally manufactured platform to serve palm trees by working in flat and uneven orchard land, palm tree heights of 4, 8, and 12 meters, and it performs pollination, pruning and harvesting services. The time of ascent and descent, the palm service, and the palm/hour productivity were measured. A randomized complete block design with three replications used a split split-plot arrangement. The nature of the land (flat or uneven) represented the main plots, the height of the palm trees (4, 8, 12) meters, the sub-plots, and the palm service operations (pollinati</p> ... Show More
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Publication Date
Fri Jun 01 2018
Journal Name
Journal Of Engineering
Evaluation of Traffic Performance of Ahmed Urabi Square in Baghdad City
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At present, smooth movement on the roads is a matter which is needed for each user. Many roads, especially in urban areas geometrically improved because of the number of vehicles increase from time to time.

In this research, Highway capacity software, HCS, 2000, will be adopted to determine the effectiveness of roundabout in terms of capacity of roundabout, delay and level of service of roundabout.

The results of the analysis indicated that the Ahmed Urabi roundabout operates under level of service F with an average control delay of 300 seconds per vehicle during the peak hours.

The through movements of Alkarrada- Aljadiriya direction (Major Direction) represent the heaviest traff

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