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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
Sat Jan 01 2022
Journal Name
Journal Of The Mechanical Behavior Of Materials
Response of composite steel-concrete cellular beams of different concrete deck types under harmonic loads
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Abstract<p>This study aims to investigate the adequacy of composite cellular beams with lightweight reinforced concrete deck slab as a structural unit for harmonic loaded buildings. The experimental program involved three fixed-ends supported beams throughout 2140 mm. Three concrete types were included: Normal Weight Concrete (NWC), Lightweight Aggregate Concrete (LWAC), and Lightweight Fiber Reinforced Aggregate Concrete (LWACF). The considered frequencies were (5, 10, 15, 20, 25, and 30) Hz. It was indicated that the harmonic load caused a significant influence on LWAC response (64% greater than NWC) and lattice cracks were observed, especially at 30 Hz. As for LWACF slab, no cracks appeared, </p> ... Show More
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Publication Date
Sun Dec 10 2023
Journal Name
Al-rafidain Journal Of Medical Sciences ( Issn 2789-3219 )
Detection of Multiple Sclerosis Lesions in Supra- and Infra-Tentorial Anatomical Regions by Double Inversion Recovery, Flair, and T2 MRI Sequences: A Comparative Study in Iraqi Patients
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Background: In young adults, multiple sclerosis is a prevalent chronic inflammatory demyelinating condition. It is characterized by white matter affection, but many individuals also have significant gray matter involvement. A double-inversion recovery pulse (DIR) pattern was recently proposed to improve the visibility of multiple sclerosis lesions. Objective: To find out how well a DIR sequence, FLAIR, and T2-weighted pulse sequences can find MS lesions in the supratentorial and infratentorial regions. Methods: A total of 37 patients with established diagnoses of multiple sclerosis were included in this cross-sectional study. Brain MRI was done using double inversion recovery, T2, and FLAIR sequences. The number of lesions was count

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Publication Date
Thu Nov 30 2023
Journal Name
Iraqi Geological Journal
Multiple and Coherent Noise Removal from X-Profile 2D Seismic Data of Southern Iraq Using Common Depth Point Muting Procedures and Depending on Madagascar Open-Source Package
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This article describes how to predict different types of multiple reflections in pre-track seismic data. The characteristics of multiple reflections can be expressed as a combination of the characteristics of primary reflections. Multiple velocities always come in lower magnitude than the primaries, this is the base for separating them during Normal Move Out correction. The muting procedure is applied in Time-Velocity analysis domain. Semblance plot is used to diagnose multiples availability and judgment for muting dimensions. This processing procedure is used to eliminate internal multiples from real 2D seismic data from southern Iraq in two stages. The first is conventional Normal Move Out correction and velocity auto picking and

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Publication Date
Sat Jul 01 2023
Journal Name
Iop Conference Series: Earth And Environmental Science
Performance Evaluation of Two Date Palm Frond Cutting Saws
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Abstract<p>Traditional tree management is laborious and costly, thus this work aimed to study the performance of two different types of frond cutting saws (reciprocating saw and vibrating saw) and examine the two saws on five date palm varieties. Four parameters were examined, including cutting time for a single frond, the power needed for cutting a single frond, frond cutting productivity expressed as tree/h, and vibration conveyed to the worker’s hand. A field experiment was designed according to the nested randomized complete block design, including five date palm varieties as the main plot and the type of saw as a sub-plot. Means were compared using the least significant differences (LSD 0</p> ... Show More
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Publication Date
Sun Feb 28 2021
Journal Name
Journal Of Economics And Administrative Sciences
Evaluation of Educational Performance according to Centralization and Decentralization
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The research aims to identify the effect of applying administrative decentralization to an educational performance by assessing educational performance before and after the process of transferring powers from the federal government (the Iraqi Ministry of Education) to local governments (governorates) as well as identifying the appropriate central or decentralized administrative system to advance the educational reality and performance. To achieve the goal of the research, educational data was collected and analyzed, as well as the measurement of educational performance indicators and analysis during two phases, the first represents the stage of applying the central system and spanned between the academic year (2011-2012) and the

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Publication Date
Sat Dec 02 2023
Journal Name
Journal Of Engineering
Performance Assessment of Pile Models Chemically Grouted by Low-Pressure Injection Laboratory Device for Improving Loose Sand
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The complexity and partially defined nature of jet grouting make it hard to predict the performance of grouted piles. So the trials of cement injection at a location with similar soil properties as the erecting site are necessary to assess the performance of the grouted piles. Nevertheless, instead of executing trial-injected piles at the pilot site, which wastes money, time, and effort, the laboratory cement injection devices are essential alternatives for evaluating soil injection ability. This study assesses the performance of a low-pressure laboratory grouting device by improving loose sandy soil injected using binders formed of Silica Fume (SF) as a chemical admixture (10% of Ordinary Portland Cement OPC mass) to di

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Publication Date
Mon Feb 01 2016
Journal Name
Swarm And Evolutionary Computation
Improving the performance of evolutionary multi-objective co-clustering models for community detection in complex social networks
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Publication Date
Sat Feb 01 2020
Journal Name
Iop Conference Series: Materials Science And Engineering
Performance of piled raft foundations under the effect of dewatering nearby an open pit
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Abstract<p>The dewatering arrangement is required in execution works and it needs more attention due to the additional vertical settlement produced on the adjacent pile foundations. Raft foundations are being increasingly utilized for construction in cases of subsoil conditions with a high water table. Also, soil displacements in adjacent un-braced deep open pit may be a reason for high damages to the close buildings and foundations systems. The aim of this study is to examine the behaviour of piled raft foundations considering different pile locations under the effect of line drain and stage drilling of nearby open foundation pit. The line drain was used as dewatering process through the soil i</p> ... Show More
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Publication Date
Fri Jan 01 2021
Journal Name
Fme Transactions
FAT-based adaptive backstepping control of an electromechanical system with an unknown input coefficient
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This paper is focused on orthogonal function approximation technique FAT-based adaptive backstepping control of a geared DC motor coupled with a rotational mechanical component. It is assumed that all parameters of the actuator are unknown including the torque-current constant (i.e., unknown input coefficient) and hence a control system with three motor control modes is proposed: 1) motor torque control mode, 2) motor current control mode, and 3) motor voltage control mode. The proposed control algorithm is a powerful tool to control a dynamic system with an unknown input coefficient. Each uncertain parameter/term is represented by a linear combination of weighting and orthogonal basis function vectors. Chebyshev polynomial is used

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Publication Date
Thu Aug 31 2017
Journal Name
Journal Of Engineering
The Phenomenon of Division and Modification of The Individual Houses in Baghdad after 2003
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The Research deals with the negative phenomena which appeared in the urban scenes of the  Iraqi cities after 2003, particularly trespassing the architectural design of the urban Individual houses.  Many academic researchers , critics, and cultural circles, drawn attention to the impact of  political and cultural variable change on such phenomena  without detailed  analysis . The research problem  is set according to central questions : If the phenomena is the trespass , what
are the sides which are being trespassed  in the division of the individual house? , If the diagnosis of the phenomena denotes perceived repetition of the cases , So what's size of this transposes on the architectural design of t

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