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.
Introduction: Cerebral hydatid disease (CHD) is rare and the multiple-cystic variety is even rarer. In this paper, we report a case of multiple CHD and explore a possible link with a preceding spontaneous intracerebral haemorrhage (ICH). Case presentation: A 27-year old gentleman with a history of surgically-evacuated, spontaneous ICH presented with severe headache, left-sided weakness - Medical Research Council (MRC) grade II - and recurrent tonic-clonic seizures, while on a full dose of anti-epileptic medication. Brain magnetic resonance imaging (MRI) scans showed multiple intra-axial cystic lesions in the right hemisphere. The cysts were removed intact using Dowling’s technique through a large temporoparietal crani
... Show MoreObjectives: The aim of this study was to assess the possible the association between +3061 (G>A, rs1143676) missense mutation in exon 24 of the integrin α-4 subunit (ITGA-4) gene and the response to natalizumab in a sample of Iraqi multiple sclerosis patients. Methods: A sample of 59 patients with multiple sclerosis (16 males and 43 females; mean age of 32 years; age range of 15 to 52 years) receiving natalizumab for at least 12 consecutive months were involved in the study between March and August/ 2022. The sample was categorized into two groups according to their response to natalizumab treatment (responders and non-responders). Polymerase chain reaction and Sanger’s sequencing for the extracted deoxyribonucleic acid was pe
... Show MoreTV drama has gone through many developmental stages until it reached and settled in the form of TV series of thirty episodes. Alongside the development of the TV technologies and the widespread of satellite channels, the form of the TV drama has changed and the series has consisted of two parts and then parts multiplied until they amounted to ten parts and more. This form of TV drama has become an artistic phenomenon, that once the series is displayed on one of the channels and achieves a noticeable success, its producers work to produce a second part of that series and so on. This form of TV drama has remained away from being researched.
This has urged the researcher to accomplish this study entitled (TV series of multiple parts fro
The growing interest in the use of chaotic techniques for enabling secure communication in recent years has been motivated by the emergence of a number of wireless services which require the service provider to provide low bit error rates (BER) along with information security. This paper investigates the feasibility of using chaotic communications over Multiple-Input-Multiple-Output (MIMO) channels. While the use of Chaotic maps can enhance security, it is seen that the overall BER performance gets degraded when compared to conventional communication schemes. In order to overcome this limitation, we have proposed the use of a combination of Chaotic modulation and Alamouti Space Time Block Code. The performance of Chaos Shift Keying (CSK) wi
... Show MoreFeed Forward Back Propagation artificial neural network (ANN) model utilizing the MATLAB Neural Network Toolbox is designed for the prediction of surface roughness of Duplex Stainless Steel during orthogonal turning with uncoated carbide insert tool. Turning experiments were performed at various process conditions (feed rate, cutting speed, and cutting depth). Utilizing the Taguchi experimental design method, an optimum ANN architecture with the Levenberg-Marquardt training algorithm was obtained. Parametric research was performed with the optimized ANN architecture to report the impact of every turning parameter on the roughness of the surface. The results suggested that machining at a cutting speed of 355 rpm with a feed rate of 0.07 m
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Viscosity is one of the most important governing parameters of the fluid flow, either in the porous media or in pipelines. So it is important to use an accurate method to calculate the oil viscosity at various operating conditions. In the literature, several empirical correlations have been proposed for predicting crude oil viscosity. However, these correlations are limited to predict the oil viscosity at specified conditions. In the present work, an extensive experimental data of oil viscosities collected from different samples of Iraqi oil reservoirs was applied to develop a new correlation to calculate the oil viscosity at various operating conditions either for dead, satura
... Show Morerop simulation models play a pivotal role in evaluating irrigation management strategies to improve water use in agriculture. The aim of this study is to verify the validity of the Aquacrop model of maize under the surface and sprinkler irrigation systems, and a cultivation system, borders and furrows, and for two varieties of Maze (Fajr and Drakma) At two different sites in Iraq, Babylon and Al-Qadisiyah governorates. An experiment was conducted to evaluate the performance of the Aquacrop model in simulating canopy cover (CC), biomass (B), dry yield, harvest index (HI), and water productivity (WP). The results of RMSE, R2, MAE, d, NSE, CC, Pe indicated good results and high compatibility between measured and simulated values. The highest a
... Show MoreThe current research aims to know the effect of teaching using multiple intelligences theory on academic achievement for students of primary school. The sample search of pupils . The research sample was divided into two groups where the first group represented the experimental group which studied the use of multiple intelligences and the second group represented the control group which studied the use of the traditional way . The search tool consisted of achievement test. Showed search results, there are statistically significant differences(0.05) between the average scores of students who have studied according to multiple intelligences between the average scores of students who have studied in accordance with the tradition way in the p
... Show MoreThis experiment was holdup in A-Faris poultry farms from 1st March to 11 of Aprile 2019. (ACTH) hormone infusion was tested in this experiment on acid-base regulation in broiler chickens. For 7 days, osmotic pumps dispensed 8 IU of ACTH in saline/kg of BW/d, or the same volume of saline as in ACTH at 1 l/h. On days 0 and 14, after the beginning of the infusions, blood samples were obtained to establish a baseline. The plasma concentrations of Na+, K+, and Cl- were decreased, whereas the partial pressure of CO2, anion gap, corticosterone, mean corpuscular hemoglobin concentration, and blood concentrations of hemoglobin and HCO - were all elevated due to the ACTH administration. When given ACTH, neither blood pH nor plasma Ca2+ levels changed
... Show MorePhotovoltaic (PV) devices are widely used renewable energy resources and have been increasingly manufactured by many firms and trademarks. This condition makes the selection of right product difficult and requires the development of a fast, accurate and easy setup that can be implemented to test available samples and select the cost effective, efficient, and reliable product for implementation. An automated test setup for PV panels using LabVIEW and several microcontroller-based embedded systems were designed, tested, and implemented. This PV testing system was fully automated, where the only human intervention required was the instalment of PV panel and set up of required testing conditions. The designed and implemented system was
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