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Cross-focusing of two chirped Gaussian laser beams and THz wave generation in plasmas of multi-ion species under a weakly relativistic and ponderomotive regime

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Plasma Science and Technology 2022年第10期24卷 1-11页

作者： M r jafari MILANI S rEZAEI M J jafari Photonics and Quantum Technologies research School Nuclear Science and Technology Research InstituteTehran 14665-678Iran Plasma and Fusion research School Nuclear Science and Technology Research InstituteTehran 14399-51113Iran

The generation of terahertz(THz)waves via the beating of two high-intensity chirped Gaussian lasers in a multi-ion-species plasma is numerically studied by taking into account the weak relativistic and ponderomotive regime of *** coupled differential equations for beamwidth parameters are extracted by introducing the dielectric function of such plasma and using WKB and paraxial ray *** amplitude of THz radiation at beat frequency resulting from the nonlinear current density induced by the beat ponderomotive force of the cross-focusing of beams was *** impacts of the chirp frequency parameter,initial laser intensity and initial ionic species density(specifically,the presence of singly and doubly charged ions)in the plasma on THz generation were *** numerical results reveal that THz radiation generation strongly depends on the chirp frequency parameter.A specific range of chirp frequencies exists for self-focusing as well as THz generation with a'turning point',where the THz emission reaches its maximum *** results show that the strength of self-focusing and consequently the generated THz radiation are reduced by increasing the density of doubly charged ionic species in the plasma due to the suppression of the nonlinear effects.

关键词： laser–plasma interaction THz generation chirped Gaussian laser beams

Intermetallic growth behavior during post deformation annealing in multilayer Ti/Al/Nb composite interfaces

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International Journal of Minerals,Metallurgy and Materials 2022年第8期29卷 1608-1617页

作者： r.jafari B.Eghbali Department of Materials Engineering Faculty of EngineeringUrmia UniversityP.O.Box 57561-165UrmiaIran Faculty of Materials Engineering Sahand University of TechnologyP.O.Box 51335-1996TabrizIran

The tri-metal Ti-Al-Nb composites were processed through three procedures:hot pressing,rolling,and hot pressing,followed by subsequent *** fabricated composites were then subjected to annealing at 600,625,and 650℃ temperatures at different *** observation at the interfaces reveals that the increase in plastic deformation strain significantly affects TiAl_(3) intermetallic layers’evolution and accelerates the layers’*** the contrary,the amount of applied strain does not significantly affect the evolution of the NbAl_(3) intermetallic layer *** was also found that Al and Ti atoms’diffusion has occurred throughout the TiAl_(3) layer,but only Al atoms diffuse through the NbAl_(3) *** slow growth rate of the NbAl_(3) intermetallic layer is due to the lack of diffusion of Nb atoms and the high activation energy of Al atoms’reaction with Nb atoms.

关键词： intermetallic compounds diffusion Ti/Al/Nb composite deformation annealing

Non-harmonic resonance of viscoelastic structures subjected to time-dependent exponentially decreasing transverse distributed loads

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Earthquake Engineering and Engineering Vibration 2023年第3期22卷 825-840页

作者： Nasrin jafari Department of Civil Engineering Isfahan University of TechnologyIsfahan 84156-83111Iran

In this paper,the non-harmonic resonance of Bernoulli viscoelastic beams,Kirchhoff viscoelastic plates,Timoshenko viscoelastic beams,and Mindlin viscoelastic plates subjected to time-dependent exponentially decreasing transverse distributed load is investigated for the first *** constitutive equations are expressed utilizing Boltzmann integral law with a constant bulk *** displacement vector is approximated by employing the separation of variables *** Laplace transformation is used to transfer equations from the time domain to the Laplace domain and vice *** novel point of the proposed method is to express,prove and calculate the critical time in which the displacement will be several times the displacement at time *** addition,this new method calculates the maximum deflection at the critical time,explicitly and exactly,without any need to follow the time-displacement curve with a low computational ***,the proposed method introduces the critical range of time so that the responses are greater than the responses at time zero.

关键词： Bernoulli and Timoshenko viscoelastic beams critical time non-harmonic resonance time-dependent decreasing exponential load Kirchhoff and Mindlin viscoelastic plates

Coarse to Fine: The role of Severe Plastic Deformation in Advancing Titanium-Based Medical Implants - A Comprehensive review

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Journal of Wuhan University of Technology(Materials Science) 2025年第1期40卷 295-306页

作者： Dragana r Mihajlović Bojan I Međo Ivana Lj Cvijović-Alagić Veljko r Djokić Faculty of Technology and Metallurgy University of BelgradeKarnegijeva 411120 BelgradeSerbia Vinča Institute of Nuclear Sci-ences-National Institute of the republic of Serbia University of Belgrade11001BeogradSerbia Innovation Centre of the Faculty of Technology and Metallurgy Karnegijeva 411120 BelgradeSerbia

This paper describes severe plastic deformation(SPD)procedures,which are utilized to form an ultrafine-grained structure in metallic *** the SPD process,a solid material sample is subjected to very high loads without a significant change in sample *** the present work,the high-pressure torsion(HPT)process,as one of the SPD techniques,which achieves a high degree of deformation and ensures refinement of the microstructure,will be discussed in more *** that grain size control is accepted as a method to obtain materials with desired characteristics,an overview of the properties of ultrafine-grained titanium-based biomaterials to be used in medicine is ***,particular attention is dedicated to the influences of HPT process parameters,primarily hydrostatic pressure,and number of revolutions during torsion,on the grain size and physical and mechanical characteristics(modulus of elasticity,microhardness,and tensile properties),corrosion resistance,and biocompatibility of the titanium-based biomaterials.A review of the literature indicates that titanium-based materials obtained by the SPD process show improved mechanical and physical properties without losing biocompatibility and corrosion resistance,which suggests that these methods of obtaining implants are something that should be further developed in the future.

关键词： high-pressure torsion process ultrafine-grained titanium-based materials electrochemical anodization physical properties mechanical properties

A non-fluorinated mechanochemically robust volumetric superhydrophobic nanocomposite

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Journal of Materials Science & Technology 2021年第7期66卷 213-225页

作者： E.Vazirinasab G.Momen r.jafari Department of Applied Sciences University of Quebec in Chicoutimi(UQAC)555boul.de I'universiteChicoutimiQuebecG7H 2B1Canada

The widespread use of water-repellent superhydrophobic surfaces is limited by the inherent fragility of their micro-and nanoscale roughness, which is prone to damage and degradation. Here, we report a non-fluorinated volumetric superhydrophobic nanocomposites that demonstrate mechanochemical robustness. The nanocomposites are produced through the addition of microscale diatomaceous earth and nanoscale fumed silica particles to high-temperature vulcanized silicone rubber. The water-repellency of the surface and bulk of nanocomposites having 120 phr of filler was determined based on the water contact angle and contact angle hysteresis. We compared the water-repellency of nanocomposites of differing diatomaceous earth to fumed silica mass ratios. Increasing the amount of diatomaceous earth enhanced the water-repellency of the nanocomposite surface, whereas an increased amount of fumed silica improved the water-repellency of the bulk material. Moreover, increasing the diatomaceous earth/fumed silica mass ratio improved the cross-linking density and hardness values of the *** being subjected to a range of mechanical durability tests, including sandpaper abrasion,knife scratching, tape peeling, water jet impact, and sandblasting, the nanocomposite maintained a water contact angle of 163. and contact angle hysteresis of 2°. When the water-repellency of the prepared nanocomposites eventually deteriorated, we restored their superhydrophobicity by removing the upper surface of the nanocomposite. This extraordinary robustness stems from the embedded low surface energy micro/nanostructures distributed throughout the nanocomposite. We also demonstrated the chemical stability, UV resistance, and self-cleaning abilities of the nanocomposite to illustrate the potential for real-life applications of this material.

关键词： Volumetric superhydrophobic Nanocomposite Diatomaceous earth Hierarchical micro/nanostructure Mechanical robustness Chemical stability Self-cleaning

Emerging potential of progranulin-dependent SorCS2 signaling in healthy and diseased nervous systems

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Neural regeneration research 2025年第9期20卷 2591-2593页

作者： Alena Salasova Anders Nykjær Danish research Institute of Translational Neuroscience DANDrITE-Nordic EMBL Partnership for Molecular Medicine and Centre of Excellence PROMEMODepartment of BiomedicineAarhus UniversityAarhusDenmark

The formation of the mammalian nervous system and its maturation into sensory,motor,cognitive,and behavioral circuits is a complex process that begins during early embryogenesis and lasts until young *** neurodevelopm... 详细信息

关键词： progr jointly CS2

Corrosion Behaviors of Two Types of Commercial Stainless Steel after Plastic Deformation

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Journal of Materials Science & Technology 2010年第9期26卷 833-838页

作者： Esmaeil jafari Materials Science and Engineering Department Islamic Azad University Shiraz Branch

The influence of deformation temperature,strain rate and alloying elements such as chromium,nickel,copper,on corrosion resistance of a 304 stainless steel after plastic deformation was *** techniques employed were tensile test at room and elevated temperature,deep drawing tests at various strain rates,X-ray diffraction test and potentiodynamic and cyclic polarization,metallography by optical and scanning electron *** showed that chromium,nickel and copper had a significant effect on corrosion resistance of steel after plastic *** was observed that corrosion resistance after plastic deformation was a function of deformation temperature and alloying elements.

关键词： Corrosion resistance Plastic deformation Stainless steel Phase transformation Polarization test

Security Strategy of Digital Medical Contents Based on Blockchain in Generative AI Model

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Computers, Materials & Continua 2025年第1期82卷 259-278页

作者： Hoon Ko Marek r.Ogiela Division of Computer Science and Engineering Sunmoon UniversityAsan31460Republic of Korea AGH University of Krakow Cryptography and Cognitive Informatics LaboratoryKrakow30-059Poland

This study presents an innovative approach to enhancing the security of visual medical data in the generative AI environment through the integration of blockchain *** combining the strengths of blockchain and generative AI,the research team aimed to address the timely challenge of safeguarding visual medical *** participating researchers conducted a comprehensive analysis,examining the vulnerabilities of medical AI services,personal information protection issues,and overall security *** multi faceted exploration led to an indepth evaluation of the model’s performance and ***,the correlation between accuracy,detection rate,and error rate was *** analysis revealed insights into the model’s strengths and limitations,while the consideration of standard deviation shed light on the model’s stability and performance *** study proposed practical improvements,emphasizing the reduction of false negatives to enhance detection rate and leveraging blockchain technology to ensure visual data integrity in medical *** blockchain to generative AI-created medical content addresses key personal information protection *** utilizing the distributed ledger system of blockchain,the research team aimed to protect the privacy and integrity of medical data especially medical *** approach not only enhances security but also enables transparent and tamperproof ***,the use of generative AI models ensures the creation of novel medical content without compromising personal information,further safeguarding patient *** conclusion,this study showcases the potential of blockchain-based solutions in the medical field,particularly in securing sensitive medical data and protecting patient *** proposed approach,combining blockchain and generative AI,offers a promising direction toward more robust and secure medical content *** research and advancements

关键词： Digitalmedical content medical diagnostic visualization security analysis generativeAI blockchain vulnerability pattern recognition

Introducing the general condition for an operator in curved space to be unitary

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Chinese Physics B 2021年第8期30卷 220-223页

作者： jafari Matehkolaee Mehdi Faculty of Physics Semnan UniversitySemnan35131-19111Iran

We investigate the general condition for an operator to be *** condition is introduced according to the definition of the position operator in curved *** a particular case,we discuss the concept of translation operator in curved space followed by its relation with an anti-Hermitian *** we introduce a universal formula for adjoint of an arbitrary linear *** procedure in this paper is totally different from others,as we explore a general approach based only on the algebra of the *** approach is only discussed for the translation operators in one-dimensional space and not for general operators.

关键词： operator theory algebraic methods unitary operator translation operator