A two-unit symmetrical composite structure with the WSMs defect layer was designed. The energy band and transmission properties are studied based on the transfer matrix theory. Due to the WSMs with the property of time-reversal breaking, the nonreciprocal Tamm states for forward and backward incidence are excited in the interface of the symmetrical composite structure. The numerical results show that the nonreciprocity of the Tamm states is enhanced with an increase in the WSMs thickness. By choosing the appropriate geometric parameters of dielectric layers, two pairs of nonreciprocal dispersive curves are obtained in the two-band gap. The present scenario can be applied in some areas, such as optical isolators and multi-channel nonreciprocal transmission devices.
设计了一种带有 WSMs 缺陷层的双单元对称复合结构。基于传递矩阵理论研究了其能带和传输特性。由于 WSMs 具有时间反向断裂的特性，对称复合结构的界面上激发了正向和反向入射的非互易 Tamm 态。数值结果表明，随着 WSM 厚度的增加，Tamm 态的非互易性增强。通过选择适当的介电层几何参数，可以在双带间隙中获得两对非互易色散曲线。本方案可应用于一些领域，如光隔离器和多通道非互易传输设备。
{"title":"Nonreciprocal transmission in composite structure with Weyl semimetal defect layer","authors":"Xin Chen, Guanxia Yu, Haodong Wang","doi":"10.1515/zna-2023-0302","DOIUrl":"https://doi.org/10.1515/zna-2023-0302","url":null,"abstract":"A two-unit symmetrical composite structure with the WSMs defect layer was designed. The energy band and transmission properties are studied based on the transfer matrix theory. Due to the WSMs with the property of time-reversal breaking, the nonreciprocal Tamm states for forward and backward incidence are excited in the interface of the symmetrical composite structure. The numerical results show that the nonreciprocity of the Tamm states is enhanced with an increase in the WSMs thickness. By choosing the appropriate geometric parameters of dielectric layers, two pairs of nonreciprocal dispersive curves are obtained in the two-band gap. The present scenario can be applied in some areas, such as optical isolators and multi-channel nonreciprocal transmission devices.","PeriodicalId":23871,"journal":{"name":"Zeitschrift für Naturforschung A","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140147801","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This work presents nonlinear and linear analyses of the rotating Navier–Stokes–Voigt fluid layer that is simultaneously heated and soluted from below, considering different boundary surfaces. The energy method is used to form the eigenvalue problem for nonlinear analysis, whereas the normal mode analysis is used for the linear analysis. The Rayleigh number is numerically calculated by employing the Galerkin technique. Both nonlinear and linear analyses yield the same Rayleigh number, indicating the absence of subcritical regions and implying global stability. The Kelvin–Voigt parameter doesn’t affect the Rayleigh number for stationary convection. However, the crucial role of this parameter is established through an energy argument. The presence of rotation, Kelvin–Voigt parameter, and solute gradient give rise to oscillatory modes. Also, the effects of rotation and solute gradient are stabilizing on the system, whereas the stabilizing effect of the Kelvin–Voigt parameter becomes evident when convection exhibits an oscillatory behavior.
{"title":"Stability analysis of thermosolutal convection in a rotating Navier–Stokes–Voigt fluid","authors":"Sweta Sharma, Sunil, Poonam Sharma","doi":"10.1515/zna-2023-0284","DOIUrl":"https://doi.org/10.1515/zna-2023-0284","url":null,"abstract":"\u0000 This work presents nonlinear and linear analyses of the rotating Navier–Stokes–Voigt fluid layer that is simultaneously heated and soluted from below, considering different boundary surfaces. The energy method is used to form the eigenvalue problem for nonlinear analysis, whereas the normal mode analysis is used for the linear analysis. The Rayleigh number is numerically calculated by employing the Galerkin technique. Both nonlinear and linear analyses yield the same Rayleigh number, indicating the absence of subcritical regions and implying global stability. The Kelvin–Voigt parameter doesn’t affect the Rayleigh number for stationary convection. However, the crucial role of this parameter is established through an energy argument. The presence of rotation, Kelvin–Voigt parameter, and solute gradient give rise to oscillatory modes. Also, the effects of rotation and solute gradient are stabilizing on the system, whereas the stabilizing effect of the Kelvin–Voigt parameter becomes evident when convection exhibits an oscillatory behavior.","PeriodicalId":23871,"journal":{"name":"Zeitschrift für Naturforschung A","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140244588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper deals with the study of propagation of shock waves in 2-D steady supersonic magnetogasdynamics flow of nonideal dusty gas using wavefront analysis method. We derived the transport equation, which determines the condition for the shock formation. Our aim is to analyze the effect of interaction of dust particles with magnetic field in nonideal gas on the evolution of shock formation and to examine how the flow patterns of the disturbance vary with respect to the variations in the physical parameters of the medium. It is found that the presence of magnetic field plays an essential role in the wave propagation phenomena. The nature of the solution with respect to the Mach number is analyzed, and it is examined how the shock formation distance changes with an increase or decrease in the value of Mach number. Also, the combined effect of nonidealness, magnetic field, and dust particles on the shock formation distance is elucidated and examined how the formation of shocks is affected by the increase in the value of corresponding physical parameters.
{"title":"Evolution of shock waves in dusty nonideal gas flow with magnetic field","authors":"Shweta, Pradeep, S. Srivastava, L. P. Singh","doi":"10.1515/zna-2023-0254","DOIUrl":"https://doi.org/10.1515/zna-2023-0254","url":null,"abstract":"\u0000 This paper deals with the study of propagation of shock waves in 2-D steady supersonic magnetogasdynamics flow of nonideal dusty gas using wavefront analysis method. We derived the transport equation, which determines the condition for the shock formation. Our aim is to analyze the effect of interaction of dust particles with magnetic field in nonideal gas on the evolution of shock formation and to examine how the flow patterns of the disturbance vary with respect to the variations in the physical parameters of the medium. It is found that the presence of magnetic field plays an essential role in the wave propagation phenomena. The nature of the solution with respect to the Mach number is analyzed, and it is examined how the shock formation distance changes with an increase or decrease in the value of Mach number. Also, the combined effect of nonidealness, magnetic field, and dust particles on the shock formation distance is elucidated and examined how the formation of shocks is affected by the increase in the value of corresponding physical parameters.","PeriodicalId":23871,"journal":{"name":"Zeitschrift für Naturforschung A","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140077976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Terahertz Technology is a promising newer technology for various applications in wireless and radar communication namely tracking and detecting radar targets. The challenging aspect of radar transmitters in the target detection process is spurious harmonic signals that affect the communication path between radar transceivers. The spurious signal can be neglected by a strong filtering method. Filtering is vital in radar transmission to avoid high spurious emission level signals. Low pass filtering at terahertz frequency range (LPFT) in microstrip structure defined in the chapter analysis to avoid the harmonics above the cut-off frequency. In this chapter, the analysis part of microstrip structured LPFT is implemented under finite difference time domain analysis at (0.3 THz to 0.5 THz) cut-off frequency. Finite difference time domain (FDTD) is the three-dimensional approach commonly used for the analysis in higher frequency applications. In this FDTD method, Maxwell equation’s partial derivatives are centred to finite frequency by discretization. LPFT 3D-plot is characterized by the signal factors of the input signal, reflected signal, and passed signal concerning time. Scattering parameters |s11| and |s21| are characterized by frequency and magnitude plots with an insertion loss of 0.3 dB. Full-wave analysis of LPFT is compared with Chebyshev and Butterworth filter at terahertz cut-off range is implemented. The comparison plot of attenuation versus relative frequency and characteristic impedance versus dielectric constant is shown with FDTD results with good agreement.
{"title":"Analysis of microstrip low pass filter at terahertz frequency range in finite difference time domain method for radar applications","authors":"K. S. Lavanya, N. Vijayalakshmi, S. Preethi","doi":"10.1515/zna-2023-0329","DOIUrl":"https://doi.org/10.1515/zna-2023-0329","url":null,"abstract":"Terahertz Technology is a promising newer technology for various applications in wireless and radar communication namely tracking and detecting radar targets. The challenging aspect of radar transmitters in the target detection process is spurious harmonic signals that affect the communication path between radar transceivers. The spurious signal can be neglected by a strong filtering method. Filtering is vital in radar transmission to avoid high spurious emission level signals. Low pass filtering at terahertz frequency range (LPFT) in microstrip structure defined in the chapter analysis to avoid the harmonics above the cut-off frequency. In this chapter, the analysis part of microstrip structured LPFT is implemented under finite difference time domain analysis at (0.3 THz to 0.5 THz) cut-off frequency. Finite difference time domain (FDTD) is the three-dimensional approach commonly used for the analysis in higher frequency applications. In this FDTD method, Maxwell equation’s partial derivatives are centred to finite frequency by discretization. LPFT 3D-plot is characterized by the signal factors of the input signal, reflected signal, and passed signal concerning time. Scattering parameters |<jats:italic>s</jats:italic>11| and |<jats:italic>s</jats:italic>21| are characterized by frequency and magnitude plots with an insertion loss of 0.3 dB. Full-wave analysis of LPFT is compared with Chebyshev and Butterworth filter at terahertz cut-off range is implemented. The comparison plot of attenuation versus relative frequency and characteristic impedance versus dielectric constant is shown with FDTD results with good agreement.","PeriodicalId":23871,"journal":{"name":"Zeitschrift für Naturforschung A","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140057261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Vikas Gupta, Abhishekh Kumar Rai, Tejmani Kumar, Akash Kumar Tarai, Manoj Kumar Gundawar, A. K. Rai
Calibration-free laser-induced breakdown spectroscopy (CF-LIBS) is successfully employed to determine the chemical composition of brass samples using the LIBS technique. The sample is irradiated with a Q-switched Nd: YAG laser with a pulse width of 5 ns to generate laser-induced plasma (LIP) on the sample surface. The time evolution spectra were recorded from the surface of the brass sample only with an accumulation of five laser shots to get one LIP spectrum. Time-resolved LIP spectra have been utilized to identify the most appropriate time window (where the plasma is optically thin and in local thermal equilibrium) suitable for CF-LIBS implementation. Stoichiometric ablation is also demonstrated for metallic brass samples with the aforementioned laser in the present study. To obtain definitive quantitative information from LIP, the characterization of the plasma, i.e., spectral line intensity, spectral line broadening, electron number density, and plasma temperature, has been analyzed in this paper. Based on two different CF-LIBS algorithms, the brass sample composition was determined and found to be in good agreement with the certified results. This paper also compares and contrasts both strategies, as well as discusses their place and importance. The results of the present manuscript illustrate the potential applicability of CF-LIBS for yielding precise and accurate compositions of brass.
{"title":"Calibration-free approaches for quantitative analysis of a brass sample","authors":"Vikas Gupta, Abhishekh Kumar Rai, Tejmani Kumar, Akash Kumar Tarai, Manoj Kumar Gundawar, A. K. Rai","doi":"10.1515/zna-2023-0280","DOIUrl":"https://doi.org/10.1515/zna-2023-0280","url":null,"abstract":"Calibration-free laser-induced breakdown spectroscopy (CF-LIBS) is successfully employed to determine the chemical composition of brass samples using the LIBS technique. The sample is irradiated with a Q-switched Nd: YAG laser with a pulse width of 5 ns to generate laser-induced plasma (LIP) on the sample surface. The time evolution spectra were recorded from the surface of the brass sample only with an accumulation of five laser shots to get one LIP spectrum. Time-resolved LIP spectra have been utilized to identify the most appropriate time window (where the plasma is optically thin and in local thermal equilibrium) suitable for CF-LIBS implementation. Stoichiometric ablation is also demonstrated for metallic brass samples with the aforementioned laser in the present study. To obtain definitive quantitative information from LIP, the characterization of the plasma, i.e., spectral line intensity, spectral line broadening, electron number density, and plasma temperature, has been analyzed in this paper. Based on two different CF-LIBS algorithms, the brass sample composition was determined and found to be in good agreement with the certified results. This paper also compares and contrasts both strategies, as well as discusses their place and importance. The results of the present manuscript illustrate the potential applicability of CF-LIBS for yielding precise and accurate compositions of brass.","PeriodicalId":23871,"journal":{"name":"Zeitschrift für Naturforschung A","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140057283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kannan Balakrishnan Yelai, Muthaian Charles Robert, Abinaya Nandagopal
This paper describes the electronic structure, bonding nature and magnetic properties of Mg0.5Ni0.5−xZnxFe2O4 (x = 0.1, 0.2, 0.3, 0.4) nano-spinel ferrite samples synthesized by the co-precipitation method. Spinel structure with Fd3̄$bar{3}$m space group is confirmed by XRD analysis with trace amounts of hematite. The results of XRD and FTIR confirm the formation of spinel structure. The estimated average crystallite size ranges from 35 to 59 nm by different methods. The FESEM analysis revealed that the samples have a generally porous aspect. Particle size analysis indicates that the average particle size is approximately 150 nm. Covalent bond exists between the tetrahedral A site – oxygen atom (A–O) and ionic nature exists between the octahedral B site – oxygen atom (B–O) in the two sub lattices of the ferrite unit cell, as determined by the maximum entropy method. Mg0.5Ni0.3Zn0.2Fe2O4 demonstrates high A–O covalency and B–O covalency/ionic boundary based on MEM electron density analysis.
本文介绍了共沉淀法合成的 Mg0.5Ni0.5-x Zn x Fe2O4 (x = 0.1, 0.2, 0.3, 0.4) 纳米尖晶石铁氧体样品的电子结构、成键性质和磁性能。通过 XRD 分析证实了该样品具有 Fd 3 ̄ $bar{3}$ m 空间群的尖晶石结构，并含有痕量的赤铁矿。XRD 和傅立叶变换红外光谱的结果证实了尖晶石结构的形成。用不同的方法估算出的平均晶粒尺寸在 35 到 59 nm 之间。FESEM 分析表明，样品总体上具有多孔性。粒度分析表明，平均粒度约为 150 nm。根据最大熵法测定，在铁氧体单位晶胞的两个子晶格中，四面体 A 位点-氧原子（A-O）之间存在共价键，八面体 B 位点-氧原子（B-O）之间存在离子键。根据 MEM 电子密度分析，Mg0.5Ni0.3Zn0.2Fe2O4 表现出较高的 A-O 共价性和 B-O 共价性/离子边界。
{"title":"Effect of zinc doping on structural, bonding nature and magnetic properties of co-precipitated magnesium–nickel ferrites","authors":"Kannan Balakrishnan Yelai, Muthaian Charles Robert, Abinaya Nandagopal","doi":"10.1515/zna-2023-0323","DOIUrl":"https://doi.org/10.1515/zna-2023-0323","url":null,"abstract":"This paper describes the electronic structure, bonding nature and magnetic properties of Mg<jats:sub>0.5</jats:sub>Ni<jats:sub>0.5−<jats:italic>x</jats:italic> </jats:sub>Zn<jats:sub> <jats:italic>x</jats:italic> </jats:sub>Fe<jats:sub>2</jats:sub>O<jats:sub>4</jats:sub> (<jats:italic>x</jats:italic> = 0.1, 0.2, 0.3, 0.4) nano-spinel ferrite samples synthesized by the co-precipitation method. Spinel structure with <jats:italic>Fd</jats:italic> <jats:inline-formula> <jats:alternatives> <m:math xmlns:m=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <m:mrow> <m:mover accent=\"true\"> <m:mrow> <m:mn>3</m:mn> </m:mrow> <m:mo>̄</m:mo> </m:mover> </m:mrow> </m:math> <jats:tex-math>$bar{3}$</jats:tex-math> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" xlink:href=\"graphic/j_zna-2023-0323_ineq_001.png\" /> </jats:alternatives> </jats:inline-formula> <jats:italic>m</jats:italic> space group is confirmed by XRD analysis with trace amounts of hematite. The results of XRD and FTIR confirm the formation of spinel structure. The estimated average crystallite size ranges from 35 to 59 nm by different methods. The FESEM analysis revealed that the samples have a generally porous aspect. Particle size analysis indicates that the average particle size is approximately 150 nm. Covalent bond exists between the tetrahedral A site – oxygen atom (A–O) and ionic nature exists between the octahedral B site – oxygen atom (B–O) in the two sub lattices of the ferrite unit cell, as determined by the maximum entropy method. Mg<jats:sub>0.5</jats:sub>Ni<jats:sub>0.3</jats:sub>Zn<jats:sub>0.2</jats:sub>Fe<jats:sub>2</jats:sub>O<jats:sub>4</jats:sub> demonstrates high A–O covalency and B–O covalency/ionic boundary based on MEM electron density analysis.","PeriodicalId":23871,"journal":{"name":"Zeitschrift für Naturforschung A","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140057166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, we present the rigorous theory of the robust inverse scattering method for the discrete high-order nonlinear Schrödinger (HNLS) equation with a nonzero boundary condition (NZBC). Using the direct scattering problem, we deduce the analyticity, symmetries, and asymptotic behaviors of the Jost solutions and scattering matrix. We also formulate the inverse scattering problem using the matrix Riemann–Hilbert problem (RHP). Furthermore, utilizing the loop group theory, we construct the multi-fold Darboux transformation (DT) within the framework of the robust inverse scattering transform. Additionally, we develop the corresponding Bäcklund transformation (BT) to obtain the multi-fold lattice soliton solutions. To derive the high-order rational solutions, we further construct the high-order DT. Finally, we theoretically and graphically analyze these solutions, which exhibit lattice breather waves, W-shape lattice solitons, high-order lattice rogue waves (RW), and their interactions.
{"title":"Robust inverse scattering analysis of discrete high-order nonlinear Schrödinger equation","authors":"Xue-Wei Yan, Yong Chen, Xin Wu","doi":"10.1515/zna-2023-0295","DOIUrl":"https://doi.org/10.1515/zna-2023-0295","url":null,"abstract":"In this study, we present the rigorous theory of the robust inverse scattering method for the discrete high-order nonlinear Schrödinger (HNLS) equation with a nonzero boundary condition (NZBC). Using the direct scattering problem, we deduce the analyticity, symmetries, and asymptotic behaviors of the Jost solutions and scattering matrix. We also formulate the inverse scattering problem using the matrix Riemann–Hilbert problem (RHP). Furthermore, utilizing the loop group theory, we construct the multi-fold Darboux transformation (DT) within the framework of the robust inverse scattering transform. Additionally, we develop the corresponding Bäcklund transformation (BT) to obtain the multi-fold lattice soliton solutions. To derive the high-order rational solutions, we further construct the high-order DT. Finally, we theoretically and graphically analyze these solutions, which exhibit lattice breather waves, W-shape lattice solitons, high-order lattice rogue waves (RW), and their interactions.","PeriodicalId":23871,"journal":{"name":"Zeitschrift für Naturforschung A","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139954007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shangbin Jiao, Qiongjie Xue, Na Li, Rui Gao, Gang Lv, Yi Wang, Yvjun Li
The research on stochastic resonance (SR) which is used to extract weak signals from noisy backgrounds is of great theoretical significance and promising application. To address the shortcomings of the classical tristable SR model, this article proposes a novel compound multistable stochastic resonance (NCMSR) model by combining the Woods–Saxon (WS) and tristable models. The influence of the parameters of the NCMSR systems on the output response performance is studied under different α stable noises. Meanwhile, the adaptive synchronization optimization algorithm based on the proposed model is employed to achieve periodic and non-periodic signal identifications in α stable noise environments. The results show that the proposed system model outperforms the tristable system in terms of detection performance. Finally, the NCMSR model is applied to 2D image processing, which achieves great noise reduction and image recovery effects.
{"title":"Novel compound multistable stochastic resonance weak signal detection","authors":"Shangbin Jiao, Qiongjie Xue, Na Li, Rui Gao, Gang Lv, Yi Wang, Yvjun Li","doi":"10.1515/zna-2023-0312","DOIUrl":"https://doi.org/10.1515/zna-2023-0312","url":null,"abstract":"The research on stochastic resonance (SR) which is used to extract weak signals from noisy backgrounds is of great theoretical significance and promising application. To address the shortcomings of the classical tristable SR model, this article proposes a novel compound multistable stochastic resonance (NCMSR) model by combining the Woods–Saxon (WS) and tristable models. The influence of the parameters of the NCMSR systems on the output response performance is studied under different <jats:italic>α</jats:italic> stable noises. Meanwhile, the adaptive synchronization optimization algorithm based on the proposed model is employed to achieve periodic and non-periodic signal identifications in <jats:italic>α</jats:italic> stable noise environments. The results show that the proposed system model outperforms the tristable system in terms of detection performance. Finally, the NCMSR model is applied to 2D image processing, which achieves great noise reduction and image recovery effects.","PeriodicalId":23871,"journal":{"name":"Zeitschrift für Naturforschung A","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139954010","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Atom-bond-connectivity (ABC) indices are obtained in analytical forms for graphene sheets, zigzag single walled carbon nanotubes (SWCNTs), and single walled carbon nanotori in terms of number of rings (r) that measures the length and the number of hexagons in between two rings (h) that dictates the width of the concerned systems. The procedures followed for ABC index have been used to obtain the expressions of augmented Zagreb and Randić indices for such systems. Logarithm of ABC indices of zigzag SWCNTs are found to correlate linearly well with the bond dissociation energies per C–C bond and the Young’s moduli of said SWCNTs with fixed number of rings (r) but varying number of hexagons (h) in between two successive rings. The plot of logarithm of ABC index versus Young’s modulus of such SWCNTs in varying both r and h simultaneously is not a straight line but fits well with the sigmoidal (Boltzmann) curve. Wiener index, one of the important distance based index, has recently been found to have similar correlations with the concerned properties of such systems. Similar plots would appear for the said properties of the zigzag SWCNTs with other degree-based indices like augmented Zagreb and Randić indices, as have been indicated from their respective expressions obtained.
{"title":"Atom-bond-connectivity (ABC) indices of graphene sheets, zigzag single walled carbon nanotubes and single walled carbon nanotori","authors":"Soukat Ghosh, Uday Maji, Swapnadeep Mondal, Bholanath Mandal","doi":"10.1515/zna-2023-0277","DOIUrl":"https://doi.org/10.1515/zna-2023-0277","url":null,"abstract":"Atom-bond-connectivity (ABC) indices are obtained in analytical forms for graphene sheets, zigzag single walled carbon nanotubes (SWCNTs), and single walled carbon nanotori in terms of number of rings (<jats:italic>r</jats:italic>) that measures the length and the number of hexagons in between two rings (<jats:italic>h</jats:italic>) that dictates the width of the concerned systems. The procedures followed for ABC index have been used to obtain the expressions of augmented Zagreb and Randić indices for such systems. Logarithm of ABC indices of zigzag SWCNTs are found to correlate linearly well with the bond dissociation energies per C–C bond and the Young’s moduli of said SWCNTs with fixed number of rings (<jats:italic>r</jats:italic>) but varying number of hexagons (<jats:italic>h</jats:italic>) in between two successive rings. The plot of logarithm of ABC index versus Young’s modulus of such SWCNTs in varying both <jats:italic>r</jats:italic> and <jats:italic>h</jats:italic> simultaneously is not a straight line but fits well with the sigmoidal (Boltzmann) curve. Wiener index, one of the important distance based index, has recently been found to have similar correlations with the concerned properties of such systems. Similar plots would appear for the said properties of the zigzag SWCNTs with other degree-based indices like augmented Zagreb and Randić indices, as have been indicated from their respective expressions obtained.","PeriodicalId":23871,"journal":{"name":"Zeitschrift für Naturforschung A","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139953895","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The structure of viscous shock-front has been investigated in a van der Waals gas between the boundary conditions for x = −ε and x = +ε considering the flow of a gas to be viscous and one-dimensional. The exact solutions for the flow parameters, fluid velocity, pressure, temperature, and change-in-entropy in the shock transition region have been found in view of the equation of state for van der Waals gases. The effects due to the coefficient of viscosity, shock strength, and nonidealness parameter have been analyzed on the structure and flow variable in the shock transition region. The results confirm that the thickness of shock-front increases with increasing value of the coefficient of viscosity and decreases with increasing value of the shock strength and nonidealness parameter of the gases.
考虑到气体的流动是粘性和一维的，研究了范德华气体在 x = -ε 和 x = +ε 边界条件之间的粘性冲击前沿结构。根据范德华气体的状态方程，找到了冲击过渡区域的流动参数、流体速度、压力、温度和熵变的精确解。分析了粘度系数、冲击强度和非理想参数对冲击过渡区结构和流动变量的影响。结果证实，冲击前沿的厚度随气体粘度系数的增大而增大，随冲击强度和非理想参数的增大而减小。
{"title":"The effects of viscosity on the structure of shock waves in a van der Waals gas","authors":"Raj Kumar Anand, Sewa Singh","doi":"10.1515/zna-2023-0252","DOIUrl":"https://doi.org/10.1515/zna-2023-0252","url":null,"abstract":"The structure of viscous shock-front has been investigated in a van der Waals gas between the boundary conditions for <jats:italic>x</jats:italic> = −<jats:italic>ε</jats:italic> and <jats:italic>x</jats:italic> = +<jats:italic>ε</jats:italic> considering the flow of a gas to be viscous and one-dimensional. The exact solutions for the flow parameters, fluid velocity, pressure, temperature, and change-in-entropy in the shock transition region have been found in view of the equation of state for van der Waals gases. The effects due to the coefficient of viscosity, shock strength, and nonidealness parameter have been analyzed on the structure and flow variable in the shock transition region. The results confirm that the thickness of shock-front increases with increasing value of the coefficient of viscosity and decreases with increasing value of the shock strength and nonidealness parameter of the gases.","PeriodicalId":23871,"journal":{"name":"Zeitschrift für Naturforschung A","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139917786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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