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New Adaptive Data Transmission Scheme Over HF Radio
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Acceptable Bit Error rate can be maintained by adapting some of the design parameters such as modulation, symbol rate, constellation size, and transmit power according to the channel state.

An estimate of HF propagation effects can be used to design an adaptive data transmission system over HF link. The proposed system combines the well known Automatic Link Establishment (ALE) together with variable rate transmission system. The standard ALE is modified to suite the required goal of selecting the best carrier frequency (channel) for a given transmission. This is based on measuring SINAD (Signal plus Noise plus Distortion to Noise plus Distortion), RSL (Received Signal Level), multipath phase distortion and BER (Bit Error Rate) for each channel in the frequency list. Channel condition evaluation is done by two arrangements. In the first an FFT analysis is used where a pilot signal is transmitted over the channel, while the data itself is used in the second arrangement. Passive channel assessment is used to avoid bad channels hence limiting the frequency pool size to be used in the point to point communication and the time required for  scanning and linking. An exchange of channel information between the transmitting and receiving stations is considered to select the modulation scheme for transmission. Mainly MPSK and MFSK are considered with different levels giving different data rate according to the channel condition. The results of the computer simulation have shown that when transmitting at a fixed channel symbol rate of 1200 symbol/sec, the information rate ranges from 2400 bps using 4FSK up to 3600 bps using 8PSK for SNR ranges from 11dB up to 26dB.

 

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Publication Date
Thu Nov 15 2018
Journal Name
Journal Of Mathematical Imaging And Vision
A New Hybrid form of Krawtchouk and Tchebichef Polynomials: Design and Application
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Publication Date
Wed Nov 01 2023
Journal Name
Iop Conference Series: Earth And Environmental Science
Two New Records of Cerceris Latreille, 1802 (Hymenoptera: Apoidea: Crabronidae) from Iraq
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Abstract<p>In a survey of the crabronid fauna of Iraq during June to October 2022; 9species belonging to the genus <italic>Cerceris</italic> Latreille, 1802 were identified. Twospecies are new record of the fauna of Iraq: <italic>C. dorsalis</italic> Eversmann, 1849 and <italic>C. priesneri</italic> Mochi, 1939. Brief description, diagnostic characters, some collecting information, and photographs of each species are provided. As well provides a key to the species depending on many morphological features especially: propodeal enclosure, semicircular plate at base of second gastral sternites and free margin of clypeus. Moreover, this study observed that most collecte</p> ... Show More
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Publication Date
Mon Aug 01 2022
Journal Name
Inorganic Chemistry Communications
Study the application of new type green corrosion inhibitors for iron metal
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Density functional theory (DFT) calculations were used to evaluate the capability of Glutamine (Gln) and its derivative chemicals as inhibitors for the anti-corrosive behavior of iron. The current work is devoted to scrutinizing reactivity descriptors (both local and global) of Gln, two states of neutral and protonated. Also, the change of Gln upon the incorporation into dipeptides was investigated. Since the number of reaction centers has increased, an enhancement in dipeptides’ inhibitory effect was observed. Thus, the adsorption of small-scale peptides and glutamine amino acids on Fe surfaces (1 1 1) was performed, and characteristics such as adsorption energies and the configuration with the highest stability and lowest energy were ca

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Publication Date
Sun Sep 01 2019
Journal Name
Baghdad Science Journal
Synthesis, Characterization and Antimicrobial Activity Study of Some New Substituted Benzoxazole Derivatives
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This research included the preparation of 2-mercaptobenzoxazole (N1) by the reaction of ortho-aminophenol with carbon disulfide in an alcoholic potassium hydroxide solution. The 2-mercapto benzoxazole (N1) was then treated with hydrazine to obtain the 2-hydrazino benzoxazole (N2). A number of hydrazones (N3-N5) were prepared through the reaction of N2 with different benzaldehydes. The compound (N6) was also prepared whereby the ring closing of hydrazone (N3) using chloroacetylchloride, while the compound (N7) was prepared by treating 2-hydrazino benzoxazole with acetylacetone. When the compound (N1) was treated with formaldehyde, it afforded the compound (N8). Also, the N9 was obtained from the reaction of N1 with chloroacetic acid in th

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Publication Date
Wed Jun 01 2022
Journal Name
Eurasian Chemical Communications
Characterization and synthesis of some new Schiff bases and their potential applications
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In this present work, [4,4`-(biphenyl-4,4`-diylbis(azan-1-yl-1-ylidene))bis(methan-1-yl-1-ylidene)bis(2-methoxyphenl)(A1),4,4`-(biphenyl-4,4`-diylbis(azan-1-yl-1-ylidene))bis(methan-1-yl-1-ylidene)diphenol(A2),1,1`-(biphenyl-4,4`-diylbis(azan-1-yl-1-ylidene))bis(methan-1-yl-1-ylidene) dinaphthalen-2-ol (A3)]C.S was prepared in 3.5% NaCl. Corrosion prevention at (293-323) K has been studied by using electrochemical measurements. It shows that the utilized inhibitors are of mixed type based on the polarization curves. The results indicated that the inhibition efficiency changes were used with a change according to the functional groups on the benzene ring and through the electrochemical technique. Temperature increases with corrosion current

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Publication Date
Sun Jul 01 2012
Journal Name
Applied Soft Computing
A new evolutionary based routing protocol for clustered heterogeneous wireless sensor networks
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Publication Date
Sun Jun 01 2014
Journal Name
Baghdad Science Journal
Synthesis and characterization of new Oxazine , Thiazine and Pyrazol derived from chalcones
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In this study, chalcones were synthesis by condensing 2-acetylpyridine with aromatic aldehyde derivatives in dilute ethanolic potassium hydroxide solution at room temperature according to Claisen-Schmidt condensation. After that, new heterocyclic derivatives such as Oxazine, Thiazine and Pyrazol were synthesis by reaction between chalcones with urea, thiourea and hydrazine hydrate respectively scheme 1. All these compounds wrer characterization by FTIR, 1H-NMR spectroscopy and elemental analysis.

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Publication Date
Thu Dec 01 2022
Journal Name
Journal Of Molecular Structure
A new thiazoldinone and triazole derivatives: Synthesis, characterization and liquid crystalline properties
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Publication Date
Mon Nov 01 2021
Journal Name
Bioorganic Chemistry
A new class of cytotoxic agents targets tubulin and disrupts microtubule dynamics
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Publication Date
Fri Jan 01 2021
Journal Name
Computers, Materials &amp; Continua
A New Hybrid Feature Selection Method Using T-test and Fitness Function
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