Jafar Ramadhan Mohammed received the B.Sc. and M.Sc. Degrees in Electronic and Communication Engineering from University of Mosul, IRAQ, in 1998, and 2001, respectively, and the Ph.D. degree in Digital Communication Engineering from Panjab University, India in Nov. 2009. He is currently an Assistant Professor at Ninevah University, IRAQ. His main research interests are in the area of Adaptive Signal Processing and its application, Beamforming, and Sidelobe cancellation.
Journal of Telecommunications and Information Technology
Conventionally, non-uniformly excited antenna arrays are synthesized by independently determining... more Conventionally, non-uniformly excited antenna arrays are synthesized by independently determining the excitation amplitude and phase of each single element. Such an approach is considered to be the most expensive and complex design method available. In this paper, the tilling technique is harnessed to synthesize non-uniformly excited antenna arrays. To apply this technique, the array elements are first divided into different subarray shapes, such as rectangles or squares known as tiles. The use of rectangular tile blocks instead of a single element architecture greatly simplifies the array design process and reduces array complexity. Next, the problem concerned with synthesizing sub-arrays comprising rectangular tile blocks is formulated and solved by using horizontal and vertical orientations of tiles having different shapes and sizes, and their larger integer expansions. The third approach to tiled design is a mixture of both previous tile architectures. A genetic algorithm is use...
Journal of Telecommunication, Electronic and Computer Engineering, 2012
The basic theme of our paper is to implement a new idea of noise reduction in the real time appli... more The basic theme of our paper is to implement a new idea of noise reduction in the real time applications using the concepts of adaptive filters. Our model which is presented as one of the solutions is based on two stages of operation with the first stage based on the ALE (Adaptive Line Enhancer) filters and the second stage on NLMS (Normalized Least Mean Square) filter. The first stage reduces the sinusoidal noise from the input signal and the second stage reduces the wideband noise. Two input sources of voice are used; one for the normal speech and the other for the noise input, using separate microphones for both signals. The first signal is of the corrupted speech signal and the second signal is of only the noise containing both wideband and narrowband noise. In the first stage the narrowband noise is reduced by using the ALE technique. The second stage gets a signal with ideally only the wideband noise which is reduced using the NLMS technique. In both the stages the concerned algorithms are used to update the filter coefficients in such a way that the noise is cancelled out from the signal and a clean speech signal is heard at the output
Journal of Telecommunication, Electronic and Computer Engineering, Aug 28, 2018
A new method for synthesising antenna array patterns with controlled sidelobes and enhanced direc... more A new method for synthesising antenna array patterns with controlled sidelobes and enhanced directivity is proposed. It relies on the relationship between the array factor and its corresponding element excitations through Fourier transform properties. Unlike the standard array synthesisbased Fourier transform methods, the proposed method enforces some specific constraints to achieve the desired goals. It involves the computation of the radiation pattern from initial element excitations of a linear array using inverse fast Fourier transform (FFT). Once the radiation pattern has been computed, the constraints are applied to modify it by forcing a wide null within the whole main beam region and preserving all the sidelobes unchanged. By doing this, the sidelobe structures of both original and modified patterns are exactly kept same. Then, a new array pattern with ideally no sidelobes can be obtained by subtracting the original array pattern from the modified pattern. Results of applying the proposed method to the uniformly and non-uniformly excited arrays are shown in the final section.
In the current fifth generation (5G) wireless communication systems, the interference mitigation ... more In the current fifth generation (5G) wireless communication systems, the interference mitigation issue becomes a major and most important task for improving the performance of such systems due to corded spectrum and increased demands for new applications. Antenna arrays controlled by adaptive algorithms are proved to be a good solution for such problem. However, there are still some practical limitations in implementing such fully adaptive arrays especially when consisting a large number of the controllable elements. Other disadvantages of such arrays include long convergence time of the algorithm and the complexity of the beamforming network. In this paper, an adaptive algorithm is connected to only limited number of the array elements instead of all elements. We found that the elements that located on the center of the array could be chosen as adaptive, while the other elements which have less effect on the array pattern are left without adaptation process. Thus, the proposed array has many advantages with compared to those of the fully adaptive arrays while maintaining the same performance in suppressing the interference signals through null steering. Simulation results show that the effectiveness of the proposed array in generating deep nulls with very short convergence time.
Journal of Telecommunication, Electronic and Computer Engineering, Dec 15, 2019
Beamforming using regular linear or planar arrays, in which their elements are uniformly spaced i... more Beamforming using regular linear or planar arrays, in which their elements are uniformly spaced is widely studied for various applications. However, in the wireless sensor network applications, such regular arrays are not possible to build. Thus, they are usually built with randomly distributed planar elements. Generating the required beamforming from such randomly distributed arrays that can provide a significant improvement in the wireless sensor network performance is a real challenging issue. In this paper, the amplitude and phase of each random element within the arbitrary bounded area is optimized such that its corresponding array pattern acts as a beam-steerable with minimum sidelobe level and a certain beamwidth. Simulation results under various optimization constraints are given to show the effectiveness of the considered random array. The effect of changing the total number of array elements on the array performance, such as beamwidth, minimum sidelobe level, and the gain were also investigated.
International journal of agricultural science and food technology, Jul 14, 2023
Sorghum is the second most important food crop after teff in Ethiopia. The objective of the study... more Sorghum is the second most important food crop after teff in Ethiopia. The objective of the study was to estimate the genetic variations, heritability, and expected genetic advances in the selected sorghum genotypes. Sixty-four sorghum genotypes were evaluated for 17 quantitative traits in 8x8 simple lattice designs at the Boko research site. The analysis of variance revealed highly significant differences among genotypes for all traits. The Phenotypic Coefficient Of Variation (PCV) ranged from 4.74% for days to flowering to 24.74% for panicle width, while Genotypic Coefficients Of Variation (GCV) ranged from 3.58% for leaf length to 20.33 % for panicle width. The highest PCV and GCV values were recorded for panicle width, head weight, and harvest index. Moderate PCV and GCV were recorded for grain filling period, grain filling rate, plant height, panicle length, and grain yield; indicating the effectiveness of selection based on the phenotypic performance of the genotypes. Broad sense heritability (H2) ranged from 24.74 % for biomass yield to 96.6% for head weight, whereas GAM ranged from 4.8% for biomass yield to 41.95% for panicle width. High H2 coupled with high GAM was observed for grain filling rate, panicle length, panicle width, head weight, grain yield, and harvest index; indicating that these characters are controlled by additive gene action and phenotypic selection for these characters will be effective. However, the information generated in the current study it can be useful for breeders who want to improve yield and yield contributing traits of sorghum.
Page 1. 2007 IEEE International Conference on Signal Processing and Communications (ICSPC 2007), ... more Page 1. 2007 IEEE International Conference on Signal Processing and Communications (ICSPC 2007), 24-27 November 2007, Dubai, United Arab Emirates MULTI-MICROPHONE NOISE REDUCTION TECHNIQUE BASED ON UPSAMPLING AND IIR-RLS FILTER ...
Journal of Telecommunications and Information Technology
Conventionally, non-uniformly excited antenna arrays are synthesized by independently determining... more Conventionally, non-uniformly excited antenna arrays are synthesized by independently determining the excitation amplitude and phase of each single element. Such an approach is considered to be the most expensive and complex design method available. In this paper, the tilling technique is harnessed to synthesize non-uniformly excited antenna arrays. To apply this technique, the array elements are first divided into different subarray shapes, such as rectangles or squares known as tiles. The use of rectangular tile blocks instead of a single element architecture greatly simplifies the array design process and reduces array complexity. Next, the problem concerned with synthesizing sub-arrays comprising rectangular tile blocks is formulated and solved by using horizontal and vertical orientations of tiles having different shapes and sizes, and their larger integer expansions. The third approach to tiled design is a mixture of both previous tile architectures. A genetic algorithm is use...
Journal of Telecommunication, Electronic and Computer Engineering, 2012
The basic theme of our paper is to implement a new idea of noise reduction in the real time appli... more The basic theme of our paper is to implement a new idea of noise reduction in the real time applications using the concepts of adaptive filters. Our model which is presented as one of the solutions is based on two stages of operation with the first stage based on the ALE (Adaptive Line Enhancer) filters and the second stage on NLMS (Normalized Least Mean Square) filter. The first stage reduces the sinusoidal noise from the input signal and the second stage reduces the wideband noise. Two input sources of voice are used; one for the normal speech and the other for the noise input, using separate microphones for both signals. The first signal is of the corrupted speech signal and the second signal is of only the noise containing both wideband and narrowband noise. In the first stage the narrowband noise is reduced by using the ALE technique. The second stage gets a signal with ideally only the wideband noise which is reduced using the NLMS technique. In both the stages the concerned algorithms are used to update the filter coefficients in such a way that the noise is cancelled out from the signal and a clean speech signal is heard at the output
Journal of Telecommunication, Electronic and Computer Engineering, Aug 28, 2018
A new method for synthesising antenna array patterns with controlled sidelobes and enhanced direc... more A new method for synthesising antenna array patterns with controlled sidelobes and enhanced directivity is proposed. It relies on the relationship between the array factor and its corresponding element excitations through Fourier transform properties. Unlike the standard array synthesisbased Fourier transform methods, the proposed method enforces some specific constraints to achieve the desired goals. It involves the computation of the radiation pattern from initial element excitations of a linear array using inverse fast Fourier transform (FFT). Once the radiation pattern has been computed, the constraints are applied to modify it by forcing a wide null within the whole main beam region and preserving all the sidelobes unchanged. By doing this, the sidelobe structures of both original and modified patterns are exactly kept same. Then, a new array pattern with ideally no sidelobes can be obtained by subtracting the original array pattern from the modified pattern. Results of applying the proposed method to the uniformly and non-uniformly excited arrays are shown in the final section.
In the current fifth generation (5G) wireless communication systems, the interference mitigation ... more In the current fifth generation (5G) wireless communication systems, the interference mitigation issue becomes a major and most important task for improving the performance of such systems due to corded spectrum and increased demands for new applications. Antenna arrays controlled by adaptive algorithms are proved to be a good solution for such problem. However, there are still some practical limitations in implementing such fully adaptive arrays especially when consisting a large number of the controllable elements. Other disadvantages of such arrays include long convergence time of the algorithm and the complexity of the beamforming network. In this paper, an adaptive algorithm is connected to only limited number of the array elements instead of all elements. We found that the elements that located on the center of the array could be chosen as adaptive, while the other elements which have less effect on the array pattern are left without adaptation process. Thus, the proposed array has many advantages with compared to those of the fully adaptive arrays while maintaining the same performance in suppressing the interference signals through null steering. Simulation results show that the effectiveness of the proposed array in generating deep nulls with very short convergence time.
Journal of Telecommunication, Electronic and Computer Engineering, Dec 15, 2019
Beamforming using regular linear or planar arrays, in which their elements are uniformly spaced i... more Beamforming using regular linear or planar arrays, in which their elements are uniformly spaced is widely studied for various applications. However, in the wireless sensor network applications, such regular arrays are not possible to build. Thus, they are usually built with randomly distributed planar elements. Generating the required beamforming from such randomly distributed arrays that can provide a significant improvement in the wireless sensor network performance is a real challenging issue. In this paper, the amplitude and phase of each random element within the arbitrary bounded area is optimized such that its corresponding array pattern acts as a beam-steerable with minimum sidelobe level and a certain beamwidth. Simulation results under various optimization constraints are given to show the effectiveness of the considered random array. The effect of changing the total number of array elements on the array performance, such as beamwidth, minimum sidelobe level, and the gain were also investigated.
International journal of agricultural science and food technology, Jul 14, 2023
Sorghum is the second most important food crop after teff in Ethiopia. The objective of the study... more Sorghum is the second most important food crop after teff in Ethiopia. The objective of the study was to estimate the genetic variations, heritability, and expected genetic advances in the selected sorghum genotypes. Sixty-four sorghum genotypes were evaluated for 17 quantitative traits in 8x8 simple lattice designs at the Boko research site. The analysis of variance revealed highly significant differences among genotypes for all traits. The Phenotypic Coefficient Of Variation (PCV) ranged from 4.74% for days to flowering to 24.74% for panicle width, while Genotypic Coefficients Of Variation (GCV) ranged from 3.58% for leaf length to 20.33 % for panicle width. The highest PCV and GCV values were recorded for panicle width, head weight, and harvest index. Moderate PCV and GCV were recorded for grain filling period, grain filling rate, plant height, panicle length, and grain yield; indicating the effectiveness of selection based on the phenotypic performance of the genotypes. Broad sense heritability (H2) ranged from 24.74 % for biomass yield to 96.6% for head weight, whereas GAM ranged from 4.8% for biomass yield to 41.95% for panicle width. High H2 coupled with high GAM was observed for grain filling rate, panicle length, panicle width, head weight, grain yield, and harvest index; indicating that these characters are controlled by additive gene action and phenotypic selection for these characters will be effective. However, the information generated in the current study it can be useful for breeders who want to improve yield and yield contributing traits of sorghum.
Page 1. 2007 IEEE International Conference on Signal Processing and Communications (ICSPC 2007), ... more Page 1. 2007 IEEE International Conference on Signal Processing and Communications (ICSPC 2007), 24-27 November 2007, Dubai, United Arab Emirates MULTI-MICROPHONE NOISE REDUCTION TECHNIQUE BASED ON UPSAMPLING AND IIR-RLS FILTER ...
Uploads
Papers by Jafar Mohammed