Zeitschrift für Naturforschung A最新文献_第2页

On the existence of simple waves for two-dimensional non-ideal magneto-hydrodynamics 论二维非理想磁流体力学简波的存在

Zeitschrift für Naturforschung A Pub Date : 2024-07-08 DOI: 10.1515/zna-2024-0069

Gaurav, L. P. Singh

{"title":"On the existence of simple waves for two-dimensional non-ideal magneto-hydrodynamics","authors":"Gaurav, L. P. Singh","doi":"10.1515/zna-2024-0069","DOIUrl":"https://doi.org/10.1515/zna-2024-0069","url":null,"abstract":"Abstract In this article, a method called characteristic decomposition is used to show the presence of simple waves for the two-dimensional compressible flow in a non-ideal magneto-hydrodynamics system. Here, a steady and pseudo-steady state magneto-hydrodynamics system is considered, and we provide a characteristic decomposition of the flow equations in both systems. This decomposition ensures the presence of a simple wave adjacent to a region of constant state for the system under consideration. Further, this result is extended as an application of the characteristic decomposition in a pseudo-steady state, and we prove the existence of a simple wave in a full magneto-hydrodynamics system by taking the vorticity and the entropy to be constant along the pseudo-flow characteristics. These results extend the fundamental theorem proposed by Courant and Friedrichs for a reducible system (R. Courant and K. O. Friedrichs, Supersonic Flow and Shock Waves, New York, Interscience Publishers, Inc., 1948, p. 464). A motivational work was carried out for an ideal gas by Li et al. (“Simple waves and a characteristic decomposition of the two dimensional compressible Euler equations,” Commun. Math. Phys. Math. Phys., vol. 267, no. 1, pp. 1–12, 2006) and for a non-ideal gas by Zafar and Sharma (“Characteristic decomposition of compressible Euler equations for a non-ideal gas in two-dimensions,” J. Math. Phys., vol. 55, no. 9, pp. 093103–093112, 2014], [M. Zafar, “A note on characteristic decomposition for two-dimensional euler system in van der waals fluids,” Int. J. Non-Linear Mech., vol. 86, pp. 33–36, 2016].","PeriodicalId":23871,"journal":{"name":"Zeitschrift für Naturforschung A","volume":"117 50","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141666559","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}

引用次数: 0

On oblique interaction of water waves with semi-infinite submerged elastic plate 论水波与半无限潜入弹性板的斜向相互作用

Zeitschrift für Naturforschung A Pub Date : 2024-06-24 DOI: 10.1515/zna-2024-0026

Tooba Mirza, Mahmood-ul Hassan, R. Nawaz

引用次数: 0

Axion-electrodynamics and the Poynting theorem 轴子电动力学和波因定理

Zeitschrift für Naturforschung A Pub Date : 2024-06-04 DOI: 10.1515/zna-2024-0055

Stanley A. Bruce

引用次数: 0

Design of fractal shaped antenna with MBBA LC material dispersed with ZnO nanoparticles for bandwidth improvement 利用分散有氧化锌纳米颗粒的 MBBA LC 材料设计分形天线以提高带宽

Zeitschrift für Naturforschung A Pub Date : 2024-05-30 DOI: 10.1515/zna-2024-0061

Nagandla Prasad, Pokkunuri Pardhasaradhi, Boddapati Taraka Phani Madhav, Gorla Venkata Ganesh, Velichalamala Sidda Reddy, Manepalli Rama Krishna Nanchara Rao, Nutakki Krishna Mohan

{"title":"Design of fractal shaped antenna with MBBA LC material dispersed with ZnO nanoparticles for bandwidth improvement","authors":"Nagandla Prasad, Pokkunuri Pardhasaradhi, Boddapati Taraka Phani Madhav, Gorla Venkata Ganesh, Velichalamala Sidda Reddy, Manepalli Rama Krishna Nanchara Rao, Nutakki Krishna Mohan","doi":"10.1515/zna-2024-0061","DOIUrl":"https://doi.org/10.1515/zna-2024-0061","url":null,"abstract":"This article proposes a compact coplanar waveguide (CPW)-fed antenna to improve proposed antenna’s bandwidth without altering its basic design. The proposed fractal shaped antenna comprises a CPW feed with a defective ground structure (DGS). The proposed antenna is operating at single frequency band (C), when the gap between two glass plates is filled with an air and covers two different frequency bands (S and C), when there is a LC material p-methoxy-benzylidene-p-n-butyl aniline (MBBA) with ZnO nanoparticles, further the proposed fractal antenna, resonating from 4.4 to 6 GHz frequency and offers 5.64 dBi peak gain with air gap and operates from 3.1 GHz to 6.8 GHz with a maximum obtained peak gain of 3.9 dBi when filled with MBBA dispersed with ZnO nano particles. IT also evident that the transition temperatures of pure MBBA are reduced when doped with ZnO nano particles. The results are compared and analyzed with the body of data available.","PeriodicalId":23871,"journal":{"name":"Zeitschrift für Naturforschung A","volume":"46 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141189971","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}

引用次数: 0

Exact solutions of Pauli–Schrödinger equation for a particle with position dependent mass and magnetic momentum in a generalized Morse potential and magnetic field 广义莫尔斯势和磁场中质量和磁动量随位置变化的粒子的保利-薛定谔方程的精确解

Zeitschrift für Naturforschung A Pub Date : 2024-05-27 DOI: 10.1515/zna-2024-0021

Fethi Madouri, Abdullah Bnyah Alanzi, Abdeldjalil Merdaci

引用次数: 0

New transition curves maintaining constant normal accelerations for vehicles 保持车辆正常加速度不变的新过渡曲线

Zeitschrift für Naturforschung A Pub Date : 2024-05-27 DOI: 10.1515/zna-2024-0052

Mehmet Pakdemirli

引用次数: 0

Bifurcation investigation, phase synchronization and FPGA implementation of a new photosensitive Fitz Hugh Nagumo neuron based meminductor 基于记忆电感器的新型光敏 Fitz Hugh Nagumo 神经元的分岔研究、相位同步和 FPGA 实现

Zeitschrift für Naturforschung A Pub Date : 2024-05-21 DOI: 10.1515/zna-2023-0247

Kevine Lena Nguemo Tchoupa, A. S. T. Kammogne, M. S. Siewe, Cedric Talonang Noufozo

{"title":"Bifurcation investigation, phase synchronization and FPGA implementation of a new photosensitive Fitz Hugh Nagumo neuron based meminductor","authors":"Kevine Lena Nguemo Tchoupa, A. S. T. Kammogne, M. S. Siewe, Cedric Talonang Noufozo","doi":"10.1515/zna-2023-0247","DOIUrl":"https://doi.org/10.1515/zna-2023-0247","url":null,"abstract":"\u0000 This paper focuses on the estimation of the nonlinear encoding and responses of a photosensitive Fitz Hugh Nagumo (FHN) neuron-based-meminductor and provides a relevant analysis of its phase synchronization. In the pattern, a Fitz Hugh–Nagumo neuron connected to a meminductor is activated by a photocell, and a time-varying current source is generated by the presence of external optical signals. This coupling is a benchmark circuit with memory similar to artificial eyes with the ability to capture and encode external signals. It is designed with the aim of studying the dynamics of a neuron with a memory effect highlighted through the meminductor. An appropriate dynamical analysis is provided using standard indicators such as bifurcations to point out thorough transitions and the nature of the electrical neuronal activities. Some couplings between two FHN neurons with meminductor using hybrid synapses composed of passive electronic components are achieved. Relevant tools are used to analyze the stability of the synchronization which gives prominent details on the selection of the appropriate coupling. The energy balance of the external system is evaluated which gives the effort to achieve encoding signals and also proves the feasibility of the proposal in real-time implementation. Simulations are performed on FPGA. The results present a good agreement. In many engineering applications, the detection of optical signals is inescapable as well as the synchronization of its signals for the transmission of the stimuli. These results could be useful for the designer.","PeriodicalId":23871,"journal":{"name":"Zeitschrift für Naturforschung A","volume":"11 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141114114","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}

引用次数: 0

Plasmonic graphene/perovskite Schottky barrier photodetector 等离子体石墨烯/perovskite 肖特基势垒光探测器

Zeitschrift für Naturforschung A Pub Date : 2024-05-16 DOI: 10.1515/zna-2024-0056

Hadiseh Shahriyari, Naser Hatefi-Kargan, Ahmadreza Daraei

{"title":"Plasmonic graphene/perovskite Schottky barrier photodetector","authors":"Hadiseh Shahriyari, Naser Hatefi-Kargan, Ahmadreza Daraei","doi":"10.1515/zna-2024-0056","DOIUrl":"https://doi.org/10.1515/zna-2024-0056","url":null,"abstract":"\u0000 In this paper the performance of a graphene/perovskite Schottky barrier photodetector is investigated theoretically for detecting infrared radiation within the spectral region of 7.5–10 μm. In order to increase the responsivity of the photodetector plasmon–polaritons are excited in the graphene layer within the specified spectral region with the aid of dielectric grating fabricated inside the photodetector structure. The results show that with the increase of the Fermi energy level in the graphene layer the wavelength where plasmon–polaritons are excited is shifted toward shorter wavelengths. This property enables the photodetector for tunable detection. The excitation of plasmon–polaritons localizes the infrared radiation incident on the photodetector to the graphene layer with a full width at half maximum of ≈12.6 nm. This localization increases the absorbance of the graphene layer considerably at peak detection wavelengths where plasmon–polaritons are excited, so that at peak detection wavelengths the absorbance of the graphene layer inside the photodetector is higher than 20 % while without the excitation of plasmon–polaritons the absorbance of the same layer is below 0.05 %. Due to this effect the responsivities of the photodetector at wavelengths where plasmon–polaritons are excited, increase more than 535 times relative to the case where plasmon–polaritons are not excited. Therefore the excitation of plasmon–polaritons not only increases the responsivity of the photodetector significantly but also enables the photodetector for tunable detection by varying the Fermi energy level in the graphene layer.","PeriodicalId":23871,"journal":{"name":"Zeitschrift für Naturforschung A","volume":"41 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140971538","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}

引用次数: 0

A deep learning method for solving thermoelastic coupling problem 解决热弹性耦合问题的深度学习方法

Zeitschrift für Naturforschung A Pub Date : 2024-05-15 DOI: 10.1515/zna-2024-0009

Ruoshi Fang, Kai Zhang, Ke Song, Yue Kai, Yong Li, B. Zheng

引用次数: 0

Synergistic effect of ZnO nanocomposite of Dodonea viscosa for corrosion inhibition in saline media 粘多糖纳米氧化锌复合材料在盐水介质中的缓蚀协同效应

Zeitschrift für Naturforschung A Pub Date : 2024-05-13 DOI: 10.1515/zna-2023-0339

Maha D. Alghamdi

{"title":"Synergistic effect of ZnO nanocomposite of Dodonea viscosa for corrosion inhibition in saline media","authors":"Maha D. Alghamdi","doi":"10.1515/zna-2023-0339","DOIUrl":"https://doi.org/10.1515/zna-2023-0339","url":null,"abstract":"Dodonea viscosa-zinc oxide (DV-ZnO) nanocomposite was synthesized and characterized using Fourier transform infrared (FTIR), thermal gravimetric method (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). The most abundant compounds in the plant extract were explored using gas chromatography-mass spectrometry (GC-MS). FTIR indicated the existence of the different functional groups, XRD showed that the nanocomposite has the hexagonal wurtzite shape of ZnO nanoparticles, SEM-EDS showed a size of 50 nm, and elemental analysis depicts the existence of the different elements in the extract, which confirms, along with TGA results, the formation of DV-ZnO nanocomposite. The nanocomposite synergistic effect was examined for anticorrosion capabilities using gravimetric, electrochemical, and surface analysis methods. Both the plant extract and the nanocomposite exhibited corrosion inhibition abilities. However, the incorporation of the plant extract with ZnO increased the inhibition efficiency by 20 %. Weight loss and electrochemical methods concluded an inhibition efficiency of 80 % for DV-ZnO nanocomposite. The inhibition of the nanocomposite is due to the adsorption of the inhibitor on the carbon steel surface, which was verified using X-ray photoelectron spectroscopy and scanning electron microscopy (SEM). The adsorption was found to follow both Langmuir and Temkin isotherms. Surface examination using atomic force microscopy (AFM) found that the carbon steel surface roughness was decreased from the sample submerged in an uninhibited medium (Sa = 121.20 nm) when adding DV-ZnO nanocomposite (Sa = 22.95 nm) and DV plant extract inhibitor (Sa = 54.73 nm).","PeriodicalId":23871,"journal":{"name":"Zeitschrift für Naturforschung A","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140940384","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}

引用次数: 0