International Journal of Engineering Research and, 2020
This thesis was written during my time at the Institute for Theoretical Information Technology of... more This thesis was written during my time at the Institute for Theoretical Information Technology of RWTH Aachen University. I would like to thank Prof. Dr. Rudolf Mathar for giving me the opportunity to pursue my doctorate at his institute and for supporting my research. Prof. Dr. Thomä deserves many thanks for acting as the second examiner of this thesis. Furthermore I would like to thank my former colleagues, especially Steven, Martijn, Markus, Niklas and Christopher, for good times as well as extensive and interesting discussions. Last but not least, I would like to thank my family: my wife Maja, my parents Elke and Matthias, and my brothers Christoph and Florian, for supporting me spiritually throughout writing this thesis.
Deep learning attempts medical image denoising either by directly learning the noise present or v... more Deep learning attempts medical image denoising either by directly learning the noise present or via first learning the image content. We observe that residual learning (RL) often suffers from signal leakage while dictionary learning (DL) is prone to Gibbs (ringing) artifacts. In this paper, we propose an unsupervised noise learning framework that enhances denoising by augmenting the limitation of RL with the strength of DL and vice versa. To this end, we propose a ten-layer deep residue network (DRN) augmented with patch-based dictionaries. The input images are presented to patch-based DL to indirectly learn the noise via sparse representation while given to the DRN to directly learn the noise. An optimum noise characterization is captured by iterating DL/DRN network against proposed loss. The denoised images are obtained by subtracting the learned noise from available data. We show that augmented DRN effectively handles high-frequency regions to avoid Gibbs artifacts due to DL while augmented DL helps to reduce the overfitting due to RL. Comparative experiments with many state-of-the-arts on MRI and CT datasets (2D/3D) including low-dose CT (LDCT) are conducted on a GPU-based supercomputer. The proposed network is trained by adding different levels of Rician noise for MRI and Poisson noise for CT images considering different nature and statistical distribution of datasets. The ablation studies are carried out that demonstrate enhanced denoising performance with minimal signal leakage and least artifacts by proposed augmented approach. INDEX TERMS Augmented noise learning, deep residue network, denoising, dictionary learning, inverse ill-posed problem, unsupervised learning.
Medical image acquisition is often intervented by unwanted noise that corrupts the information co... more Medical image acquisition is often intervented by unwanted noise that corrupts the information content. This paper introduces an unsupervised medical image denoising technique that learns noise characteristics from the available images and constructs denoised images. It comprises of two blocks of data processing, viz., patch-based dictionaries that indirectly learn the noise and residual learning (RL) that directly learns the noise. The model is generalized to account for both 2D and 3D images considering different medical imaging instruments. The images are considered one-by-one from the stack of MRI/CT images as well as the entire stack is considered, and decomposed into overlapping image/volume patches. These patches are given to the patch-based dictionary learning to learn noise characteristics via sparse representation while given to the RL part to directly learn the noise properties. K-singular value decomposition (K-SVD) algorithm for sparse representation is used for trainin...
This is the first work which has investigated the gamma-gamma turbulence model while considering ... more This is the first work which has investigated the gamma-gamma turbulence model while considering several types of numerical integration approaches. Basing on stability and skewness opinions, this investigation declares the suitability of Matsuno and Quasi-Adams-Bashforth 2 methods for developing true gamma-gamma turbulence model. This is followed by highlighting the need of LDPC coding to meet the challenges in outdoor optical wireless communication system. The performance of proposed linearly punctured Re-jagged AR4JA LDPC code has been investigated further to declare its suitability to be applied in outdoor optical wireless communication system.
2015 Eighth International Conference on Mobile Computing and Ubiquitous Networking (ICMU), 2015
The robustness to uncertainty of noise power is one of main challenges to spectrum sensing techni... more The robustness to uncertainty of noise power is one of main challenges to spectrum sensing technique. Since the occurrence of noise power uncertainty causes the detection performance of spectrum sensing techniques significantly degrade. In this paper, we propose two novel schemes of two-stage spectrum sensing for cognitive radio under environment as noise power uncertainty. The two-stage spectrum sensing technique combines two conventional spectrum sensing techniques to perform spectrum sensing by exploiting their individual advantages. The proposed two-stage spectrum sensing scheme exploits the merits of ED, MME and CAV techniques to determine the existence of the primary user. The ED performs spectrum sensing within a short time and offers a reliable detection at high SNRs condition. MME and CAV are robust to noise power uncertainty. Due to the combination of these techniques, the proposed schemes offer much more reliable detection when the uncertainty of noise power occurs. Even though the proposed technique takes the longest time in sensing period among two-stage spectrum sensing techniques, it is worth using this period of time to protect the primary user from harmful interference caused by the secondary user.
A microscopic nucleon–nucleon (NN) interaction is derived from the popular relativistic-mean-fiel... more A microscopic nucleon–nucleon (NN) interaction is derived from the popular relativistic-mean-field (RMF) theory Lagrangian and used to obtain the optical potential by folding it with the RMF densities of cluster and daughter nuclei. The NN-interaction is remarkably related to the inbuilt fundamental parameters of RMF theory, and the results of the application of the so obtained optical potential, made to exotic cluster radioactive decays and α+α scattering, are found comparable to that for the well-known, phenomenological M3Y effective NN-interaction. The RMF-based NN-interaction can also be used to calculate a number of other nuclear observables.
Due to extremely high demand of mobile phones among people, over the years there has been a great... more Due to extremely high demand of mobile phones among people, over the years there has been a great demand for the support of various applications and security services. 2G and 3G provide two levels of security through: encryption and authentication. This paper presents performance analysis and comparison between the algorithms in terms of time complexity. The parameters considered for comparison are processing power and input size. Security features may have adverse effect on quality of services offered to the end users and the system capacity. The computational cost overhead that the security protocols and algorithms impose on lightweight end users devices is analyzed. The results of analysis reveal the effect of authentication and encryption algorithms of 2G and 3G on system performance defined in terms of throughput which will further help in quantifying the overhead caused due to security.
... So, electrostatic potential difference between the nanotube cap and outside is . ... The curr... more ... So, electrostatic potential difference between the nanotube cap and outside is . ... The current density due to emission depends on many factors such as work function, electronic structure of the nanotube cap, nanotube length, diameter, and density. ...
IEEE Journal of the Electron Devices Society, 2022
In the present investigation, we studied the structural stability and electronic properties of ba... more In the present investigation, we studied the structural stability and electronic properties of bare and various adsorbed gas molecules ZGaNNR-2, ZGaNNR-4 and ZGaNNR-6 configurations. The electronic properties of all considered ZGaNNR configurations exhibit the metallic behaviour and it is verified through their band structures and densities of states. Based on binding energy/adsorption calculations, Bare-ZGaNNR-6 and O 2-ZGaNNR-6 configurations found the most thermostatic stable and energetically favoured configurations among all other considered ZGaNNRs. In transmission spectra, many distinct conductive states are observed in case of CO 2-ZGaNNR-6. The selectivity of CO 2 /O 2 ZGaNNR has emerged as the most preferred (24.6) one among all considered configurations. CO 2-ZGaNNR-6 is emerged as the fast sensing device due to the lower recovery time (0.14 sec). The proposed device proves the high sensing capability towards the nano-scale devices.
The paper presents the structural stability and electronic properties of Zigzag Gallium Nitride n... more The paper presents the structural stability and electronic properties of Zigzag Gallium Nitride nano ribbons(ZGaNNR) by considering the lithium(Li) atom by employing density functional theory (DFT). Li atom has been considered as a passivating element at various symmetric sites. By using Li atoms, a significant impact has been observed on the structural and electronic characteristics of ZGaNNRs. Bare@edges_both structure emerged to be the most energetically stable among other structures. For Li-passivation@edge_Ga structures, the minimum band gap has been noticed for III-V group family of nanoribbons. Interestingly, other structures of ZGaNNRs turn metallic nature irrespective of the Li site. Further, Li-bare@edge_N structure possesses the highest Fermi velocity as compared to other structures. This is useful for designing high speed interconnect applications. Further, we investigated the effective mass of various Li-ZGaNNR structures using standard two probe models. The effective mass of H-bare@edge_N structure reveals the highest effective mass in both valence and conduction bands. The proposed work proves the high capability towards the designing of the nano-scale devices.
The reaction of 9,10-phenanthrenequinone (PQ) with [M II (H)(CO)(X)(PPh 3) 3 ] in boiling toluene... more The reaction of 9,10-phenanthrenequinone (PQ) with [M II (H)(CO)(X)(PPh 3) 3 ] in boiling toluene leads to the homolytic cleavage of the M II −H bond, affording the paramagnetic trans-[M(PQ)(PPh 3) 2 (CO)X] (M = Ru, X = Cl, 1; M = Os, X = Br, 3) and cis-[M(PQ)(PPh 3) 2 (CO)X] (M = Ru, X = Cl, 2; M = Os, X = Br, 4) complexes. Single-crystal X-ray structure determinations of 1, 2•toluene, and 4•CH 2 Cl 2 , EPR spectra, and density functional theory (DFT) calculations have substantiated that 1−4 are 9,10-phenanthrenesemiquinone radical (PQ •−) complexes of ruthenium(II) and osmium(II) and are defined as trans-[Ru II (PQ •−)(PPh 3) 2 (CO)Cl] (1), cis-[Ru II (PQ •−)(PPh 3) 2 (CO)Cl] (2), trans-[Os II (PQ •−)(PPh 3) 2 (CO) Br] (3), and cis-[Os II (PQ •−)(PPh 3) 2 (CO)Br] (4). Two comparatively longer C−O [average lengths: 1, 1.291(3) Å; 2•toluene, 1.281(5) Å; 4•CH 2 Cl 2 , 1.300(8) Å] and shorter C−C lengths [1, 1.418(5) Å; 2•toluene, 1.439(6) Å; 4•CH 2 Cl 2 , 1.434(9) Å] of the OO chelates are consistent with the presence of a reduced PQ •− ligand in 1−4. A minor contribution of the alternate resonance form, trans-or cis-[M I (PQ)(PPh 3) 2 (CO)X], of 1−4 has been predicted by the anisotropic X-and Q-band electron paramagnetic resonance spectra of the frozen glasses of the complexes at 25 K and unrestricted DFT calculations on 1, trans-[Ru(PQ)(PMe 3) 2 (CO)Cl] (5), cis-[Ru(PQ)(PMe 3) 2 (CO)Cl] (6), and cis-[Os(PQ)(PMe 3) 2 (CO)Br] (7). However, no thermodynamic equilibria between [M II (PQ •−)(PPh 3) 2 (CO)X] and [M I (PQ)(PPh 3) 2 (CO)X] tautomers have been detected. 1−4 undergo one-electron oxidation at −0.06, −0.05, 0.03, and −0.03 V versus a ferrocenium/ferrocene, Fc + /Fc, couple because of the formation of PQ complexes as trans-[Ru II (PQ)(PPh 3) 2 (CO)Cl] + (1 +), cis-[Ru II (PQ)(PPh 3) 2 (CO)Cl] + (2 +), trans-[Os II (PQ)(PPh 3) 2 (CO)Br] + (3 +), and cis-[Os II (PQ)(PPh 3) 2 (CO)Br] + (4 +). The trans isomers 1 and 3 also undergo oneelectron reduction at −1.11 and −0.96 V, forming PQ 2− complexes trans-[Ru II (PQ 2−)(PPh 3) 2 (CO)Cl] − (1 −) and trans-[Os II (PQ 2−)(PPh 3) 2 (CO)Br] − (3 −). Oxidation of 1 by I 2 affords diamagnetic 1 + I 3 − in low yields. Bond parameters of 1 + I 3 − [C− O, 1.256(3) and 1.258(3) Å; C−C, 1.482(3) Å] are consistent with ligand oxidation, yielding a coordinated PQ ligand. Origins of UV−vis/near-IR absorption features of 1−4 and the electrogenerated species have been investigated by spectroelectrochemical measurements and time-dependent DFT calculations on 5, 6, 5 + , and 5 − .
Page X band EPR spectral parameters of 3 and 1complexes 2 Redox potentials of 1-3 complexes in CH... more Page X band EPR spectral parameters of 3 and 1complexes 2 Redox potentials of 1-3 complexes in CH2Cl2 solution (0.20 M [N(n-Bu)4]PF6) at 298 K 2 Gas phase optimized geometries of 1 and 2 (at the RB3LYP level of the theory) 2 Optimized coordinates 3-9
Page No. Materials Syntheses Physical measurements HPTLC measurement to establish the generation ... more Page No. Materials Syntheses Physical measurements HPTLC measurement to establish the generation of pyridine-2-aldehyde during the cleavage of 2,2′-pyridil (PCO) Identification of H2 gas by exact match of the retention time of authentic sample using GC IR spectra of c-2 rad , c-3 ac .½toluene and t-2 rad UV-vis/NIR spectra Cyclic Voltammetry of c-2 rad and t-2 rad Study of Kinetic Isotope Effect Hyperfine splitting of the X-Band EPR spectra of c-2 rad Optimized geometries of AMe rad , c-2 rad , c-2Me rad , t-2Me rad and c-3Me ac. Monitoring of the conversion of PyCOOH −• to PyCOOin c-2 rad by UV-vis/NIR absorption spectra Photoactive orbitals of c-3 ac responsible for low energy absorptions X-ray crystallographic data collection and refinement of c-3 ac .½toluene (CCDC 833917) ORTEP plot showing two disordered phenyl rings (30% probability level) of c-3ac.½toluene Experimental bond lengths (Å) and bond angles (°) of c-3 ac .½toluene Density functional theory (DFT) calculations Optimized bond lengths (Å) and bond angles (°) of AMe rad , c-2 rad , c-2Me rad , t-2Me rad and c-3Me ac Significant calculated and experimental bond lengths (Å) 10 Excitation energies (λ, nm), oscillator strengths (f), transition types and dominant contributions of charge transfer bands obtained from TD DFT calculations 10 Optimized coordinates 12 References 15
Short term load forecasting is very essential to the operation of electricity companies. It enhan... more Short term load forecasting is very essential to the operation of electricity companies. It enhances the energy-efficient and reliable operation of power system. Artificial Neural Networks are employed for non-linear short term load forecasting owing to their powerful nonlinear mapping capabilities. These are generally trained through back-propagation, genetic algorithm (GA), particle swarm optimization (PSO) and artificial immune system (AIS). All these algorithms have specific benefits in terms of accuracy, speed of convergence and historical data requirement for training. In this paper a hybrid AIS is proposed, which is a combination of back-propagation with AIS to get faster convergence, lesser historical data requirement for training with a little compromise in accuracy.
Orthogonal frequency division multiple access technique has attracted much attention for broadban... more Orthogonal frequency division multiple access technique has attracted much attention for broadband wireless access in the fourth generation and fifth generation wireless communication systems. To achieve a high data rate, communication systems require proper resource allocation and subcarrier assignment (RASA). This demands sophisticated signal processing algorithms which are computationally complex. One of the possible solutions to this lies in the parallel processing of computationally intensive algorithms, to speedup the processes. This paper presents a parallel implementation of the Hungarian algorithm for subcarrier assignment and proposes a parallel RASA algorithm for resource and subcarrier assignment problems. The proposed RASA's algorithm implementation demonstrates superior performance in terms of execution time (complexity) and fairness ratio in comparison to Hungarian and amplitude craving greedy algorithms. The complexity in terms of an execution time of Hungarian and RASA algorithms are compared with a single thread and four threads implementation under open multi-processing environment.
Orthogonal frequency division multiplexing (OFDM) is currently the most used technique for the hi... more Orthogonal frequency division multiplexing (OFDM) is currently the most used technique for the high-data-rate transmission. However, OFDM systems have an inherent drawback in that the transmitted signals suffer from a high peak-to-average power ratio (PAPR). Partial transmit sequence (PTS) is generally applied to reduce the PAPR of an OFDM signal in wireless communication systems. Here, the search complexity for optimal phase vector increases exponentially with the number of phase vectors, since it involves an extensive random search over all the combinations of the allowed phase vectors. In this paper, a swarm intelligence algorithm for phase optimization based on the Firefly algorithm (FF) is applied to search the optimal combination of phase vectors. The proposed algorithm provides a superior trade-off between the improved PAPR performance and computational complexity when compared to the PTS scheme for a large number of sub-blocks. Simulation results show that the Firefly-algorithm-based PTS (FF-PTS) algorithm is an efficient method to achieve superior PAPR characteristics for OFDM signals when compared to conventional algorithms with very few parameters to adjust.
This paper presents a novel technique in channel equalization. Wireless communication system is a... more This paper presents a novel technique in channel equalization. Wireless communication system is affected by inter-symbol interference, co-channel interference and Burst noise interference in the presence of additive white Gaussian noise. Different equalization techniques have been used to mitigate these effects using Artificial Neural Networks based Multilayer Perceptron Network, Radial Basis Function, Recurrent Network, Fuzzy and Adaptive Neuro fuzzy System, and also using linear adaptive LMS, RLS system. In this paper we proposed a RBF based equalizer which is trained using wilcoxon learning method. The equalizer presented shows considerable performance gain. Simulation studies have been conducted to demonstrate the performance of wilcoxon training for this class of problem.
The current demand of advance communication field is high data rate in addition to both power eff... more The current demand of advance communication field is high data rate in addition to both power efficiency and lower bit error rate. This can be fulfilled by the single carrier modulation while compromising the trade-off between the power efficiency and bit error rate. But, in the frequency selective fading environment, to achieve high data rate is very difficult for single carrier modulation scheme. Considering an advance step towards the multicarrier modulation scheme, it is possible to get high data rate in the multipath fading channel without degrading the bit error rate performance. To achieve better performance using multicarrier modulation the subcarriers must be orthogonal to each other. This is what we get in Orthogonal Frequency Division Multiplexing (OFDM) technique. But the great disadvantage of the OFDM technique is its high Peak to Average Power Ratio (PAPR). This book presents the Selected Mapping Technique (SLM), its modified versions and a new SLM technique for reduci...
Proceedings of the 2015 Third International Conference on Computer, Communication, Control and Information Technology (C3IT), 2015
Wireless Broadband services heavily rely on Orthogonal Frequency Division Multiplexing (OFDM) tec... more Wireless Broadband services heavily rely on Orthogonal Frequency Division Multiplexing (OFDM) technique. OFDM has several advantages which makes it suitable for high speed data communications. One of the major drawback of OFDM is its high peak-to-average power ratio (PAPR). There are several methods to overcome this drawback. Partial Transmit Sequence (PTS) is one of them. In this paper, a modified version of the iterative flipping algorithm has been proposed i.e. modified flipping PTS (M-PTS), which reduces the performance gap between the iterative flipping algorithm (I-PTS) and the conventional PTS technique. In the proposed algorithm, performance analysis has been done with considering performance/ complexity trade-off.
International Journal of Engineering Research and, 2020
This thesis was written during my time at the Institute for Theoretical Information Technology of... more This thesis was written during my time at the Institute for Theoretical Information Technology of RWTH Aachen University. I would like to thank Prof. Dr. Rudolf Mathar for giving me the opportunity to pursue my doctorate at his institute and for supporting my research. Prof. Dr. Thomä deserves many thanks for acting as the second examiner of this thesis. Furthermore I would like to thank my former colleagues, especially Steven, Martijn, Markus, Niklas and Christopher, for good times as well as extensive and interesting discussions. Last but not least, I would like to thank my family: my wife Maja, my parents Elke and Matthias, and my brothers Christoph and Florian, for supporting me spiritually throughout writing this thesis.
Deep learning attempts medical image denoising either by directly learning the noise present or v... more Deep learning attempts medical image denoising either by directly learning the noise present or via first learning the image content. We observe that residual learning (RL) often suffers from signal leakage while dictionary learning (DL) is prone to Gibbs (ringing) artifacts. In this paper, we propose an unsupervised noise learning framework that enhances denoising by augmenting the limitation of RL with the strength of DL and vice versa. To this end, we propose a ten-layer deep residue network (DRN) augmented with patch-based dictionaries. The input images are presented to patch-based DL to indirectly learn the noise via sparse representation while given to the DRN to directly learn the noise. An optimum noise characterization is captured by iterating DL/DRN network against proposed loss. The denoised images are obtained by subtracting the learned noise from available data. We show that augmented DRN effectively handles high-frequency regions to avoid Gibbs artifacts due to DL while augmented DL helps to reduce the overfitting due to RL. Comparative experiments with many state-of-the-arts on MRI and CT datasets (2D/3D) including low-dose CT (LDCT) are conducted on a GPU-based supercomputer. The proposed network is trained by adding different levels of Rician noise for MRI and Poisson noise for CT images considering different nature and statistical distribution of datasets. The ablation studies are carried out that demonstrate enhanced denoising performance with minimal signal leakage and least artifacts by proposed augmented approach. INDEX TERMS Augmented noise learning, deep residue network, denoising, dictionary learning, inverse ill-posed problem, unsupervised learning.
Medical image acquisition is often intervented by unwanted noise that corrupts the information co... more Medical image acquisition is often intervented by unwanted noise that corrupts the information content. This paper introduces an unsupervised medical image denoising technique that learns noise characteristics from the available images and constructs denoised images. It comprises of two blocks of data processing, viz., patch-based dictionaries that indirectly learn the noise and residual learning (RL) that directly learns the noise. The model is generalized to account for both 2D and 3D images considering different medical imaging instruments. The images are considered one-by-one from the stack of MRI/CT images as well as the entire stack is considered, and decomposed into overlapping image/volume patches. These patches are given to the patch-based dictionary learning to learn noise characteristics via sparse representation while given to the RL part to directly learn the noise properties. K-singular value decomposition (K-SVD) algorithm for sparse representation is used for trainin...
This is the first work which has investigated the gamma-gamma turbulence model while considering ... more This is the first work which has investigated the gamma-gamma turbulence model while considering several types of numerical integration approaches. Basing on stability and skewness opinions, this investigation declares the suitability of Matsuno and Quasi-Adams-Bashforth 2 methods for developing true gamma-gamma turbulence model. This is followed by highlighting the need of LDPC coding to meet the challenges in outdoor optical wireless communication system. The performance of proposed linearly punctured Re-jagged AR4JA LDPC code has been investigated further to declare its suitability to be applied in outdoor optical wireless communication system.
2015 Eighth International Conference on Mobile Computing and Ubiquitous Networking (ICMU), 2015
The robustness to uncertainty of noise power is one of main challenges to spectrum sensing techni... more The robustness to uncertainty of noise power is one of main challenges to spectrum sensing technique. Since the occurrence of noise power uncertainty causes the detection performance of spectrum sensing techniques significantly degrade. In this paper, we propose two novel schemes of two-stage spectrum sensing for cognitive radio under environment as noise power uncertainty. The two-stage spectrum sensing technique combines two conventional spectrum sensing techniques to perform spectrum sensing by exploiting their individual advantages. The proposed two-stage spectrum sensing scheme exploits the merits of ED, MME and CAV techniques to determine the existence of the primary user. The ED performs spectrum sensing within a short time and offers a reliable detection at high SNRs condition. MME and CAV are robust to noise power uncertainty. Due to the combination of these techniques, the proposed schemes offer much more reliable detection when the uncertainty of noise power occurs. Even though the proposed technique takes the longest time in sensing period among two-stage spectrum sensing techniques, it is worth using this period of time to protect the primary user from harmful interference caused by the secondary user.
A microscopic nucleon–nucleon (NN) interaction is derived from the popular relativistic-mean-fiel... more A microscopic nucleon–nucleon (NN) interaction is derived from the popular relativistic-mean-field (RMF) theory Lagrangian and used to obtain the optical potential by folding it with the RMF densities of cluster and daughter nuclei. The NN-interaction is remarkably related to the inbuilt fundamental parameters of RMF theory, and the results of the application of the so obtained optical potential, made to exotic cluster radioactive decays and α+α scattering, are found comparable to that for the well-known, phenomenological M3Y effective NN-interaction. The RMF-based NN-interaction can also be used to calculate a number of other nuclear observables.
Due to extremely high demand of mobile phones among people, over the years there has been a great... more Due to extremely high demand of mobile phones among people, over the years there has been a great demand for the support of various applications and security services. 2G and 3G provide two levels of security through: encryption and authentication. This paper presents performance analysis and comparison between the algorithms in terms of time complexity. The parameters considered for comparison are processing power and input size. Security features may have adverse effect on quality of services offered to the end users and the system capacity. The computational cost overhead that the security protocols and algorithms impose on lightweight end users devices is analyzed. The results of analysis reveal the effect of authentication and encryption algorithms of 2G and 3G on system performance defined in terms of throughput which will further help in quantifying the overhead caused due to security.
... So, electrostatic potential difference between the nanotube cap and outside is . ... The curr... more ... So, electrostatic potential difference between the nanotube cap and outside is . ... The current density due to emission depends on many factors such as work function, electronic structure of the nanotube cap, nanotube length, diameter, and density. ...
IEEE Journal of the Electron Devices Society, 2022
In the present investigation, we studied the structural stability and electronic properties of ba... more In the present investigation, we studied the structural stability and electronic properties of bare and various adsorbed gas molecules ZGaNNR-2, ZGaNNR-4 and ZGaNNR-6 configurations. The electronic properties of all considered ZGaNNR configurations exhibit the metallic behaviour and it is verified through their band structures and densities of states. Based on binding energy/adsorption calculations, Bare-ZGaNNR-6 and O 2-ZGaNNR-6 configurations found the most thermostatic stable and energetically favoured configurations among all other considered ZGaNNRs. In transmission spectra, many distinct conductive states are observed in case of CO 2-ZGaNNR-6. The selectivity of CO 2 /O 2 ZGaNNR has emerged as the most preferred (24.6) one among all considered configurations. CO 2-ZGaNNR-6 is emerged as the fast sensing device due to the lower recovery time (0.14 sec). The proposed device proves the high sensing capability towards the nano-scale devices.
The paper presents the structural stability and electronic properties of Zigzag Gallium Nitride n... more The paper presents the structural stability and electronic properties of Zigzag Gallium Nitride nano ribbons(ZGaNNR) by considering the lithium(Li) atom by employing density functional theory (DFT). Li atom has been considered as a passivating element at various symmetric sites. By using Li atoms, a significant impact has been observed on the structural and electronic characteristics of ZGaNNRs. Bare@edges_both structure emerged to be the most energetically stable among other structures. For Li-passivation@edge_Ga structures, the minimum band gap has been noticed for III-V group family of nanoribbons. Interestingly, other structures of ZGaNNRs turn metallic nature irrespective of the Li site. Further, Li-bare@edge_N structure possesses the highest Fermi velocity as compared to other structures. This is useful for designing high speed interconnect applications. Further, we investigated the effective mass of various Li-ZGaNNR structures using standard two probe models. The effective mass of H-bare@edge_N structure reveals the highest effective mass in both valence and conduction bands. The proposed work proves the high capability towards the designing of the nano-scale devices.
The reaction of 9,10-phenanthrenequinone (PQ) with [M II (H)(CO)(X)(PPh 3) 3 ] in boiling toluene... more The reaction of 9,10-phenanthrenequinone (PQ) with [M II (H)(CO)(X)(PPh 3) 3 ] in boiling toluene leads to the homolytic cleavage of the M II −H bond, affording the paramagnetic trans-[M(PQ)(PPh 3) 2 (CO)X] (M = Ru, X = Cl, 1; M = Os, X = Br, 3) and cis-[M(PQ)(PPh 3) 2 (CO)X] (M = Ru, X = Cl, 2; M = Os, X = Br, 4) complexes. Single-crystal X-ray structure determinations of 1, 2•toluene, and 4•CH 2 Cl 2 , EPR spectra, and density functional theory (DFT) calculations have substantiated that 1−4 are 9,10-phenanthrenesemiquinone radical (PQ •−) complexes of ruthenium(II) and osmium(II) and are defined as trans-[Ru II (PQ •−)(PPh 3) 2 (CO)Cl] (1), cis-[Ru II (PQ •−)(PPh 3) 2 (CO)Cl] (2), trans-[Os II (PQ •−)(PPh 3) 2 (CO) Br] (3), and cis-[Os II (PQ •−)(PPh 3) 2 (CO)Br] (4). Two comparatively longer C−O [average lengths: 1, 1.291(3) Å; 2•toluene, 1.281(5) Å; 4•CH 2 Cl 2 , 1.300(8) Å] and shorter C−C lengths [1, 1.418(5) Å; 2•toluene, 1.439(6) Å; 4•CH 2 Cl 2 , 1.434(9) Å] of the OO chelates are consistent with the presence of a reduced PQ •− ligand in 1−4. A minor contribution of the alternate resonance form, trans-or cis-[M I (PQ)(PPh 3) 2 (CO)X], of 1−4 has been predicted by the anisotropic X-and Q-band electron paramagnetic resonance spectra of the frozen glasses of the complexes at 25 K and unrestricted DFT calculations on 1, trans-[Ru(PQ)(PMe 3) 2 (CO)Cl] (5), cis-[Ru(PQ)(PMe 3) 2 (CO)Cl] (6), and cis-[Os(PQ)(PMe 3) 2 (CO)Br] (7). However, no thermodynamic equilibria between [M II (PQ •−)(PPh 3) 2 (CO)X] and [M I (PQ)(PPh 3) 2 (CO)X] tautomers have been detected. 1−4 undergo one-electron oxidation at −0.06, −0.05, 0.03, and −0.03 V versus a ferrocenium/ferrocene, Fc + /Fc, couple because of the formation of PQ complexes as trans-[Ru II (PQ)(PPh 3) 2 (CO)Cl] + (1 +), cis-[Ru II (PQ)(PPh 3) 2 (CO)Cl] + (2 +), trans-[Os II (PQ)(PPh 3) 2 (CO)Br] + (3 +), and cis-[Os II (PQ)(PPh 3) 2 (CO)Br] + (4 +). The trans isomers 1 and 3 also undergo oneelectron reduction at −1.11 and −0.96 V, forming PQ 2− complexes trans-[Ru II (PQ 2−)(PPh 3) 2 (CO)Cl] − (1 −) and trans-[Os II (PQ 2−)(PPh 3) 2 (CO)Br] − (3 −). Oxidation of 1 by I 2 affords diamagnetic 1 + I 3 − in low yields. Bond parameters of 1 + I 3 − [C− O, 1.256(3) and 1.258(3) Å; C−C, 1.482(3) Å] are consistent with ligand oxidation, yielding a coordinated PQ ligand. Origins of UV−vis/near-IR absorption features of 1−4 and the electrogenerated species have been investigated by spectroelectrochemical measurements and time-dependent DFT calculations on 5, 6, 5 + , and 5 − .
Page X band EPR spectral parameters of 3 and 1complexes 2 Redox potentials of 1-3 complexes in CH... more Page X band EPR spectral parameters of 3 and 1complexes 2 Redox potentials of 1-3 complexes in CH2Cl2 solution (0.20 M [N(n-Bu)4]PF6) at 298 K 2 Gas phase optimized geometries of 1 and 2 (at the RB3LYP level of the theory) 2 Optimized coordinates 3-9
Page No. Materials Syntheses Physical measurements HPTLC measurement to establish the generation ... more Page No. Materials Syntheses Physical measurements HPTLC measurement to establish the generation of pyridine-2-aldehyde during the cleavage of 2,2′-pyridil (PCO) Identification of H2 gas by exact match of the retention time of authentic sample using GC IR spectra of c-2 rad , c-3 ac .½toluene and t-2 rad UV-vis/NIR spectra Cyclic Voltammetry of c-2 rad and t-2 rad Study of Kinetic Isotope Effect Hyperfine splitting of the X-Band EPR spectra of c-2 rad Optimized geometries of AMe rad , c-2 rad , c-2Me rad , t-2Me rad and c-3Me ac. Monitoring of the conversion of PyCOOH −• to PyCOOin c-2 rad by UV-vis/NIR absorption spectra Photoactive orbitals of c-3 ac responsible for low energy absorptions X-ray crystallographic data collection and refinement of c-3 ac .½toluene (CCDC 833917) ORTEP plot showing two disordered phenyl rings (30% probability level) of c-3ac.½toluene Experimental bond lengths (Å) and bond angles (°) of c-3 ac .½toluene Density functional theory (DFT) calculations Optimized bond lengths (Å) and bond angles (°) of AMe rad , c-2 rad , c-2Me rad , t-2Me rad and c-3Me ac Significant calculated and experimental bond lengths (Å) 10 Excitation energies (λ, nm), oscillator strengths (f), transition types and dominant contributions of charge transfer bands obtained from TD DFT calculations 10 Optimized coordinates 12 References 15
Short term load forecasting is very essential to the operation of electricity companies. It enhan... more Short term load forecasting is very essential to the operation of electricity companies. It enhances the energy-efficient and reliable operation of power system. Artificial Neural Networks are employed for non-linear short term load forecasting owing to their powerful nonlinear mapping capabilities. These are generally trained through back-propagation, genetic algorithm (GA), particle swarm optimization (PSO) and artificial immune system (AIS). All these algorithms have specific benefits in terms of accuracy, speed of convergence and historical data requirement for training. In this paper a hybrid AIS is proposed, which is a combination of back-propagation with AIS to get faster convergence, lesser historical data requirement for training with a little compromise in accuracy.
Orthogonal frequency division multiple access technique has attracted much attention for broadban... more Orthogonal frequency division multiple access technique has attracted much attention for broadband wireless access in the fourth generation and fifth generation wireless communication systems. To achieve a high data rate, communication systems require proper resource allocation and subcarrier assignment (RASA). This demands sophisticated signal processing algorithms which are computationally complex. One of the possible solutions to this lies in the parallel processing of computationally intensive algorithms, to speedup the processes. This paper presents a parallel implementation of the Hungarian algorithm for subcarrier assignment and proposes a parallel RASA algorithm for resource and subcarrier assignment problems. The proposed RASA's algorithm implementation demonstrates superior performance in terms of execution time (complexity) and fairness ratio in comparison to Hungarian and amplitude craving greedy algorithms. The complexity in terms of an execution time of Hungarian and RASA algorithms are compared with a single thread and four threads implementation under open multi-processing environment.
Orthogonal frequency division multiplexing (OFDM) is currently the most used technique for the hi... more Orthogonal frequency division multiplexing (OFDM) is currently the most used technique for the high-data-rate transmission. However, OFDM systems have an inherent drawback in that the transmitted signals suffer from a high peak-to-average power ratio (PAPR). Partial transmit sequence (PTS) is generally applied to reduce the PAPR of an OFDM signal in wireless communication systems. Here, the search complexity for optimal phase vector increases exponentially with the number of phase vectors, since it involves an extensive random search over all the combinations of the allowed phase vectors. In this paper, a swarm intelligence algorithm for phase optimization based on the Firefly algorithm (FF) is applied to search the optimal combination of phase vectors. The proposed algorithm provides a superior trade-off between the improved PAPR performance and computational complexity when compared to the PTS scheme for a large number of sub-blocks. Simulation results show that the Firefly-algorithm-based PTS (FF-PTS) algorithm is an efficient method to achieve superior PAPR characteristics for OFDM signals when compared to conventional algorithms with very few parameters to adjust.
This paper presents a novel technique in channel equalization. Wireless communication system is a... more This paper presents a novel technique in channel equalization. Wireless communication system is affected by inter-symbol interference, co-channel interference and Burst noise interference in the presence of additive white Gaussian noise. Different equalization techniques have been used to mitigate these effects using Artificial Neural Networks based Multilayer Perceptron Network, Radial Basis Function, Recurrent Network, Fuzzy and Adaptive Neuro fuzzy System, and also using linear adaptive LMS, RLS system. In this paper we proposed a RBF based equalizer which is trained using wilcoxon learning method. The equalizer presented shows considerable performance gain. Simulation studies have been conducted to demonstrate the performance of wilcoxon training for this class of problem.
The current demand of advance communication field is high data rate in addition to both power eff... more The current demand of advance communication field is high data rate in addition to both power efficiency and lower bit error rate. This can be fulfilled by the single carrier modulation while compromising the trade-off between the power efficiency and bit error rate. But, in the frequency selective fading environment, to achieve high data rate is very difficult for single carrier modulation scheme. Considering an advance step towards the multicarrier modulation scheme, it is possible to get high data rate in the multipath fading channel without degrading the bit error rate performance. To achieve better performance using multicarrier modulation the subcarriers must be orthogonal to each other. This is what we get in Orthogonal Frequency Division Multiplexing (OFDM) technique. But the great disadvantage of the OFDM technique is its high Peak to Average Power Ratio (PAPR). This book presents the Selected Mapping Technique (SLM), its modified versions and a new SLM technique for reduci...
Proceedings of the 2015 Third International Conference on Computer, Communication, Control and Information Technology (C3IT), 2015
Wireless Broadband services heavily rely on Orthogonal Frequency Division Multiplexing (OFDM) tec... more Wireless Broadband services heavily rely on Orthogonal Frequency Division Multiplexing (OFDM) technique. OFDM has several advantages which makes it suitable for high speed data communications. One of the major drawback of OFDM is its high peak-to-average power ratio (PAPR). There are several methods to overcome this drawback. Partial Transmit Sequence (PTS) is one of them. In this paper, a modified version of the iterative flipping algorithm has been proposed i.e. modified flipping PTS (M-PTS), which reduces the performance gap between the iterative flipping algorithm (I-PTS) and the conventional PTS technique. In the proposed algorithm, performance analysis has been done with considering performance/ complexity trade-off.
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Papers by Sarat Patra