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joe-1095
Pilot Based Channel Estimation and Synchronization in OFDM System
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Channel estimation and synchronization are considered the most challenging issues in Orthogonal Frequency Division Multiplexing (OFDM) system. OFDM is highly affected by synchronization errors that cause reduction in subcarriers orthogonality, leading to significant performance degradation. The synchronization errors cause two issues: Symbol Time Offset (STO), which produces inter symbol interference (ISI) and Carrier Frequency Offset (CFO), which results in inter carrier interference (ICI). The aim of the research is to simulate Comb type pilot based channel estimation for OFDM system showing the effect of pilot numbers on the channel estimation performance and propose a modified estimation method for STO with less number of pilot to mitigate ISI effect. Channel estimation is simulated for different pilot number with 16QAM modulation in Ped-A Rayleigh channel. The STO effect assumed less than the cyclic prefix length to minimize ISI and maintain the orthogonality between subcarriers. The simulation results show that the high number of pilots are needed to achieve good channel estimation in case no synchronization used while similar results are achieved with smaller number of pilots if the propose modification on the synchronization method are used aligned with the channel estimation. The proposed system is evaluated in terms of BER and SNR.

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Publication Date
Sat Dec 31 2022
Journal Name
Mathematical Modelling Of Engineering Problems
Experimental and Numerical Study of Open Channel Flow with T-Section Artificial Bed Roughness
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Experimental and numerical studies have been conducted on the effects of bed roughness elements such as cubic and T-section elements that are regularly half-channel arrayed on one side of the river on turbulent flow characteristics and bed erosion downstream of the roughness elements. The experimental study has been done for two types of bed roughness elements (cubic and T-section shape) to study the effect of these elements on the velocity profile downstream the elements with respect to different water flow discharges and water depths. A comparison between the cubic and T-section artificial bed roughness showed that the velocity profile downstream the T-section increased in smooth side from the river and decrease in the rough side

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Publication Date
Mon Aug 01 2011
Journal Name
Journal Of Engineering
LDPC CODED MULTIUSER MC-CDMA PERFORMANCE OVERMULTIPATH RAYLEIGH FADING CHANNEL
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This work presents the simulation of a Low density Parity Check (LDPC) coding scheme with
multiuserMulti-Carrier Code Division Multiple Access (MC-CDMA) system over Additive White
Gaussian Noise (AWGN) channel and multipath fading channels. The decoding technique used in
the simulation was iterative decoding since it gives maximum efficiency with ten iterations.
Modulation schemes that used are Phase Shift Keying (BPSK, QPSK and 16 PSK), along with the
Orthogonal Frequency Division Multiplexing (OFDM). A 12 pilot carrier were used in the estimator
to compensate channel effect. The channel model used is Long Term Evolution (LTE) channel with
Technical Specification TS 25.101v2.10 and 5 MHz bandwidth including the chan

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Publication Date
Fri Oct 20 2023
Journal Name
Ibn Al-haitham Journal For Pure And Applied Sciences
Qualitative and Quantitative Estimation of Total Phenols in Narcissus tazettaL. Bulbs
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Narcissus tazetta, a member of the Amaryllidaceae family, is known to be rich in bioactive metabolites such as alkaloids, phenolics and flavonoids, which have been found in nearly every species in this family. N. tazetta cultivated in Iraq, had not previously been studied for its active components; thus, the current study used phytochemical screening and phenolic compounds estimation, both qualitatively and quantitatively. Results showed that the plant alcoholic extract was rich in alkaloids, polyphenols and flavonoids besides tannins, polysaccharides and saponins. Qualitatively; TLC and HPLC chromatogram for total phenolics and flavonoids compounds revealed the presence of Gallic acid (GA), Caffeic acid (CA), Paracumar

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Publication Date
Sat Feb 01 2020
Journal Name
International Journal Of Electrical And Computer Engineering (ijece)
PSS/E based placement wind/PV hybrid system to improve stability of Iraqi grid
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<span lang="EN-US">Proper employment of Hybrid Wind/ PV system is often implemented near the load, and it is linked with the grid to study dynamic stability analysis. Generally, instability is because of sudden load demand variant and variant in renewable sources generation. As well as, weather variation creates several factors that affect the operation of the integrated hybrid system. So this paper introduces output result of a PV /wind via power electronic technique; DC chopper; that is linked to Iraqi power system to promote the facilitating achievement of Wind/ PV voltage. Moreover, PSS/E is used to study dynamic power stability for hybrid system which is attached to an effective region of Iraqi Network. The hybrid system

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Publication Date
Thu Dec 01 2011
Journal Name
Journal Of Economics And Administrative Sciences
Eliminate harmful side – effects of Controls System by designing Activity – Based Responsibility Accounting model
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This research has come out with that, function-based responsibility accounting system has harmful side – effects preventing it of achieving its controlling objective, that is, goal congruence, which are due to its un integrated measures, its focus on measuring measurable behaviors while neglecting behaviors that are hardly measured, and its dependence on standard operating procedures.

In addition, the system hypotheses and measures are designed to fit previous business environment, not the current environment.

The research has also concluded that the suggestive model, that is, activity-based responsibility accounting is designed to get ride of harmful side – effects of functi

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Publication Date
Sat Sep 30 2017
Journal Name
Al-khwarizmi Engineering Journal
Implementation of Transmitter Zigbee System based on Wireless Sensor Network of IEEE 802.15.4 Standard
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Abstract

 

Zigbee is considered to be one of the wireless sensor networks (WSNs) designed for short-range communications applications. It follows IEEE 802.15.4 specifications that aim to design networks with lowest cost and power consuming in addition to the minimum possible data rate. In this paper, a transmitter Zigbee system is designed based on PHY layer specifications of this standard. The modulation technique applied in this design is the offset quadrature phase shift keying (OQPSK) with half sine pulse-shaping for achieving a minimum possible amount of phase transitions. In addition, the applied spreading technique is direct sequence spread spectrum (DSSS) technique, which has

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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
Mon Dec 18 2017
Journal Name
Al-khwarizmi Engineering Journal
High Order Sliding Mode Observer-Based Output Feedback Controller Design For Electro-Hydraulic System
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A perturbed linear system with property of strong observability ensures that there is a sliding mode observer to estimate the unknown form inputs together with states estimation. In the case of the electro-hydraulic system with piston position measured output, the above property is not met. In this paper, the output and its derivatives estimation were used to build a dynamic structure that satisfy the condition of strongly observable. A high order sliding mode observer (HOSMO) was used to estimate both the resulting unknown perturbation term and the output derivatives. Thereafter with one signal from the whole system (piton position), the piston position make tracking to desire one with a simple linear output feedback controller after ca

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Publication Date
Thu Dec 14 2023
Journal Name
Iete Journal Of Research
Performance Enhancement of VLC-NOMA Employing Beamforming Function based vehicle-to-multivehicle Communication system
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Publication Date
Mon Dec 20 2021
Journal Name
Baghdad Science Journal
IoT System on Dynamic Fish Feeder Based on Fish Existence for Agriculture Aquaponic Breeders
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Maintaining and breeding fish in a pond are a crucial task for a large fish breeder. The main issues for fish breeders are pond management such as the production of food for fishes and to maintain the pond water quality. The dynamic or technological system for breeders has been invented and becomes important to get maximum profit return for aquaponic breeders in maintaining fishes. This research presents a developed prototype of a dynamic fish feeder based on fish existence. The dynamic fish feeder is programmed to feed where sensors detected the fish's existence. A microcontroller board NodeMCU ESP8266 is programmed for the developed h

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