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Nano Research 2021年第5期14卷 1450-1456页

作者： petra S.pálvölgyi Daniel Sebők Imre Szenti Eva Bozo Henri Ervasti Olli pitkänen Jari Hannu Heli Jantunen Marko E.Leinonen Sami Myllymäki Akos Kukovecz Krisztian Kordas Microelectronics Research Unit Faculty of Information and Electrical EngineeringUniversity of OuluP.O.Box 4500FI-90570OuluFinland Interdisciplinary Excellence Centre Department of Applied and Environmental ChemistryUniversity of SzegedRerrich Béla tér 1H-6720SzegedHungary Centre for Wireless Communications University of OuluP.O.Box 4500FI-90570OuluFinland

In the next generation wireless communication systems operating at near terahertz frequencies, dielectric substrates with the lowest possible permittivity and loss factor are becoming essential. In this work, highly porous (98.9% ± 0.1%) and lightweight silica foams (0.025 ± 0.005 g/cm3), that have extremely low relative permittivity (εr = 1.018 ± 0.003 at 300 GHz) and corresponding loss factor (tan δplate-assisted sol-gel method. After dip-coating the slabs of foams with a thin film of cellulose nanofibers, sufficiently smooth surfaces are obtained, on which it is convenient to deposit electrically conductive planar thin films of metals important for applications in electronics and telecommunication devices. Here, micropatterns of Ag thin films are sputtered on the substrates through a shadow mask to demonstrate double split-ring resonator metamaterial structures as radio frequency filters operating in the sub-THz band.

关键词： low-permittivity materials low-loss dielectrics templated sol-gel synthesis silica foams 6G telecommunication

production of charmonium(like) states in e^+ e^- interactions

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Chinese physics C 2008年第6期32卷 488-491页

作者： p.pakhlov Institute for Theoretical and Experimental physics B.Cheremushkinskaya25117218MoscowRussia

We present a search for new charmonium like states in e^＋e^- annihilation using the initial-state radiation and the process e^＋e^- →J/ψ D（^＊）D（^＊）. The analyses are based on a huge data sample recorded near ... 详细信息

关键词： charmonium new states e^+e^- annihilation initial state radiation

Recent progress of CERN RD50 Collaboration

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中国有色金属学会会刊：英文版 2006年第B01期16卷 133-136页

作者： p.LUUKKA Helsinki Institute of physics CERN /EPCH-1211 GenevaSwitzerland

The objective of the CERN RD50 Collaboration is to develop radiation hard semiconductor detectors for very high luminosity colliders, in particular, for the upgrade of the large hadron collider (LHC) which itself is scheduled to be operational in 2007. The approach of the RD50 has two major research lines, material engineering and device engineering. These are further subdivided into projects covering defect characterization and engineering, new detector materials, detector characterization, new detector structures and full detector systems. presently, 264 members from 53 institutes are actively participating in the RD50 Collaboration. Detectors made of defect engineered substrates, e.g. high resistivity magnetic Czochralski (MCz-Si), epitaxial silicon (Epi-Si) on Czochralski silicon (Cz-Si) substrate, intentionally thermal donor (TD) compensated p-type MCz-Si and oxygen enriched (DOFZ) silicon, have been demonstrated by the RD50 Collaboration. An overview and highlights of the results of these defect engineering techniques were given in this report.

关键词：欧洲原子能研究机构 RD50协作组辐射硬度半导体探测器成员单位研究进展直拉硅衬底

Metaheuristics-based Clustering with Routing Technique for Lifetime Maximization in Vehicular Networks

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Computers, Materials & Continua 2023年第1期74卷 1107-1122页

作者： p.Muthukrishnan p.Muthu Kannan Saveetha School of Engineering Saveetha Institute of Medical and Technical SciencesSaveetha UniversitySaveetha NagarThandalamChennai602105TamilnaduIndia

Recently,vehicular ad hoc networks(VANETs)finds applicability in different domains such as security,rescue operations,intelligent transportation systems(ITS),*** has unique features like high mobility,limited mobility patterns,adequate topologymodifications,and wireless *** the benefits of VANET,scalability is a challenging issue which could be addressed by the use of cluster-based routing *** enables the vehicles to perform intercluster communication via chosen CHs and optimal *** main drawback of VANET network is the network unsteadiness that results in minimum *** order to avoid reduced network lifetime in VANET,this p.per presents an enhanced metaheuristics based clustering with multihop routing technique for lifetime maximization(EMCMHR-LM)in *** presented EMCMHR-LM model involves the procedure of arranging clusters,cluster head(CH)selection,and route selection appropriate for *** presentedEMCMHR-LMmodel uses slime mold optimization based clustering(SMO-C)technique to group the vehicles into ***,an enhanced wild horse optimization based multihop routing(EWHO-MHR)protocol by the optimization of network *** presented EMCMHR-LMmodel is simulated usingNetwork Simulator(NS3)tool and the simulation outcomes reported the enhanced performance of the proposed EMCMHR-LM technique over the other models.

关键词： Scalability VANET clustering multihop routing metaheuristics route selection fitness function

Experimental studies and phase field modeling of microstructure evolution during solidification with electromagnetic stirring

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中国有色金属学会会刊：英文版 2010年第S3期20卷 774-780页

作者： p.GERALD TENNYSON p.KUMAR H.LAKSHMI G.pHANIKUMAR p.DUTTA Department of Metallurgical and Materials Engineering Indian Institute of Technology National Facility for Semisolid Forming Department of Mechanical EngineeringIndian Institute of Science

Thixocasting requires manufacturing of billets with non-dendritic *** alloy A356 billets were produced by rheocasting in a mould placed inside a linear electromagnetic *** heat treatment was used to produce a transition from rosette to globular *** current and the duration of stirring were explored as control *** induction heating of the billet during stirring was quantified using experimentally determined thermal *** effect of processing parameters on the dendrite fragmentation was *** computational modeling of the process was performed using phase-field modeling of alloy solidification in order to gain insight into the process of morphological changes of a solid during this process.A non-isothermal alloy solidification model was used for *** morphological evolution under such imposed thermal cycles was simulated and compared with experimentally determined *** scaling using the thermosolutal diffusion distances was used to overcome computational difficulties in quantitative comparison at system *** results were interpreted in the light of existing theories of microstructure refinement and globularisation.

关键词： electromagnetic stirring non-dendritic phase field modeling microstructure

Cryogenic and conventional milling of AZ91 magnesium alloy

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Journal of Magnesium and Alloys 2024年第6期12卷 2503-2519页

作者： Vikas Marakini Srinivasa pai p Gururaj Bolar Bhaskara p Achar Department of Mechanical Engineering Nitte(Deemed to be University)NMAM Institute of Technology(NMAMIT)Nitte 574110India Department of Mechanical and Industrial Engineering Manipal Institute of TechnologyManipal Academy of Higher EducationManipal 576104India

Use of magnesium is the need of the hour due to its low density as well as its high strength-to-weight and stiffness-to-weight ratio *** study focuses on the effectiveness of liquid nitrogen(LN_(2))assisted cryogenic machining on the surface integrity(SI)characteristics of AZ91 magnesium *** milling using uncoated carbide inserts have been performed under liquid nitrogen(LN_(2))assisted cryogenic condition and compared with conventional(dry)*** are performed using machining parameters in terms of cutting speeds of 325,475,625 m/min,feed rates of 0.05,0.1,0.15 mm/teeth and depth of cuts of 0.5,1,1.5 mm *** significant surface integrity characteristics such as surface roughness,microhardness,microstructure,and residual stresses have been *** of SI characteristics with respect to milling parameters have been identified using statistical technique such as ANOVA and signal-to-noise(S/N)ratio ***,the multi criteria decision making(MCDM)techniques such as additive ratio assessment method(ARAS)and complex proportional assessment(COpRAS)have been utilized to identify the optimal conditions for milling AZ91 magnesium alloy under both dry and cryogenic *** of LN_(2)during machining,resulted in reduction in machining temperature by upto 29%with a temperature drop from 251.2℃under dry condition to 178.5℃in cryogenic *** showed the advantage of performing cryogenic milling in improving the surface integrity to a significant *** machining considerably minimized the roughness by upto 28%and maximised the microhardness by upto 23%,when compared to dry *** speed has caused significant impact on surface roughness(95.33%-dry,92.92%-cryogenic)and surface microhardness(80.33%-dry,82.15%-cryogenic).Due to the reduction in machining temperature,cryogenic condition resulted in compressive residual stresses(maximumσ║=-113 Mpa)on the alloy *** indicate no

关键词： Magnesium alloy Cryogenic machining Roughness Microhardness Microstructure Residual stress Multi criteria decision making

Restructuring of plasmonic nanoparticle aggregates with arbitrary particle size distribution in pulsed laser fields

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Chinese physics B 2016年第11期25卷 563-570页

作者： A E Ershov A p Gavrilyuk S V Karpov S p.polyutov Institute of Computational Modeling Russian Academy of SciencesKrasnoyarsk 660036Russia L.V.Kirensky Institute of physics of the Russian Academy of Sciences Krasnoyarsk 660036Russia Siberian Federal University Krasnoyarsk 660028Russia Siberian State Aerospace University Krasnoyarsk 660037Russia

We have studied processes of interaction of pulsed laser radiation with resonant groups of plasmonic nanoparticles（resonant domains） in large colloidal nanoparticle aggregates having different interparticle gaps and particle size *** processes are responsible for the origin of nonlinear optical effects and photochromic reactions in multiparticle *** describe photo-induced transformations in resonant domains and alterations in their absorption spectra remaining after the pulse action,we introduce the factor of spectral *** on calculation of changes in thermodynamic,mechanical,and optical characteristics of the domains,the histograms of the spectrum photomodification factor have been obtained for various interparticle gaps,an average particle size,and the degree of *** in spectra have been analyzed depending on the intensity of laser radiation and various combinations of size characteristics of *** obtained results can be used to predict manifestation of photochromic effects in composite materials containing different plasmonic nanoparticle aggregates in pulsed laser fields.

关键词： resonant arbitrary pulsed dipole manifestation alterations extinction remaining aggregate colloidal

Atomic-scale simulations of material behaviors and tribology properties for BCC metal film

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Chinese physics B 2016年第1期25卷 412-418页

作者： H D Aristizabal p A parra p Lopez E Restrepo-parra pCM Computational Applications Universidad Nacional de Colombia-Sede ManizalesA.A.127ManizalesColombi Universidad Cató1ica de Manizales A.A.357ManizalesColombia

This work has two main purposes：（i） introducing the basic concepts of molecular dynamics analysis to material scientists and engineers, and （ii） providing a better understanding of instrumented indentation measurements, presenting an example of nanoindentation and scratch test simulations. To reach these purposes, three-dimensional molecular dynamics （MD） simulations of nanoindentation and scratch test technique were carried out for generic thin films that present BCC crystalline structures. Structures were oriented in the plane （100） and placed on FCC diamond substrates. A pair wise potential was employed to simulate the interaction between atoms of each layer and a repulsive radial potential was used to represent a spherical tip indenting the sample. Mechanical properties of this generic material were obtained by varying the indentation depth and dissociation energy. The load-unload curves and coefficient of friction were found for each test; on the other hand, dissociation energy was varied showing a better mechanical response for films that present grater dissociation energy. Structural change evolution was observed presenting vacancies and slips as the depth was varied.

关键词： molecular dynamics pair wise potential repulsive radial potential dissociation energy

OpTIMAL pRICING OF A pERSONALIZED pRODUCT

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Journal of Systems Science and Systems Engineering 2008年第1期17卷 30-35页

作者： Suresh p.SETHI School of Management The University of Texas at Dallas 800 W.Campbell Rd.RichardsonTX 75080

This p.per deals with optimal pricing of a personalized product such as a personal portrait or photo. A new model of the pricing structure inspired by two real-life cases is introduced to the literature and solved to obtain optimal photo sitting fees and the final product price. A sensitivity analysis with respect to the problem parameters is performed.

关键词： personalized product pricing salvage loss

Feature-Based Aggregation and Deep Reinforcement Learning:A Survey and Some New Implementations

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IEEE/CAA Journal of Automatica Sinica 2019年第1期6卷 1-31页

作者： Dimitri p.Bertsekas the Department of Electrical Engineering and Computer Science and the Laboratory for Information and Decision SystemsMassachusetts Institute of Technology

In this p.per we discuss policy iteration methods for approximate solution of a finite-state discounted Markov decision problem, with a focus on feature-based aggregation methods and their connection with deep reinforcement learning schemes. We introduce features of the states of the original problem, and we formulate a smaller "aggregate" Markov decision problem, whose states relate to the features. We discuss properties and possible implementations of this type of aggregation, including a new approach to approximate policy iteration. In this approach the policy improvement operation combines feature-based aggregation with feature construction using deep neural networks or other calculations. We argue that the cost function of a policy may be approximated much more accurately by the nonlinear function of the features provided by aggregation, than by the linear function of the features provided by neural networkbased reinforcement learning, thereby potentially leading to more effective policy improvement.

关键词： Reinforcement learning dynamic programming Markovian decision problems aggregation feature-based architectures policy iteration deep neural networks rollout algorithms