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The role of Nanodispersed Nitrides in the Sintering of Silicon Nitride Ceramics

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Plasma Science and Technology 2010年第1期12卷 46-48页

作者： M.GEOrGIEVA G.VISSOKOV I.GrANCHArOV r.f.SILVA f.J.OLIVEIrA Department of Technology of Inorganic Substances University of Chemical Technology and Metallurgy Institute of Catalysis Bulgarian Academy of Sciences Ceramics and Glass Eng. Department CICECO University of Aveiro

The synthesis of ceramics based on silicon nitride using nanopowders of TiN and Si3N4 as additives was studied. The ceramic compositions were pressurelessly sintered under ni- trogen atmosphere at different temperatures （1550℃, 1650℃ and 1750℃） with a heating rate of 10℃/min and a holding time of 2 h. The nanodispersed nitrides （NDN） were produced by electric-arc plasma synthesis and characterized. The ceramic composites obtained with nanoparticles of 1wt% to 5wt% TiN and 20wt% Si3N4 were characterized by scanning electron microscopy （SEM）, atom force microscopy （AfM） and energy-dispersive spectrometry （EDX）. The effect of the addition of nanodispersed powders on the mechanical properties and microstructure of Si3N4 ceramics was investigated.

关键词： silicon nitride ceramics nanocomposites nanopowders

flow Management Mechanism in Software-Defined Network

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Computers, Materials & Continua 2022年第1期70卷 1437-1459页

作者： Eugene Tan Yung-Wey Chong Mohammed f.r.Anbar National Advanced IPv6 Centre Universiti Sains MalaysiaUSMPenangMalaysia

Software-defined networking(SDN)is a paradigm shift in modern ***,centralised controller architecture in SDNimposed flow setup overhead issue as the control plane handles all flows regardless of size and *** frameworks strictly reduce control plane overhead and it does not focus on rule placement of the flows ***,existing frameworks do not focus on managing elephant flows like ***,the proposed mechanism will use the flow statistics gathering method such as random packet sampling to determine elephant flow and microflow via a predefined *** mechanism will ensure that the control plane works at an optimum workload because the controller only manages elephant flows via reactive routing and rule placement *** routing has reduced link bandwidth usage below the pre-defined ***,rule placement has increased average throughput and total transfer to 238%.Meanwhile,the data plane switches will be able to forward microflows via multipath wildcard routing without invoking controller in greater responding time by 85 ms faster in two Transmission Control Protocol(TCP)traffic and achieved 11%and 12%higher total transfer size and throughput ***,the controller’s workload reduced significantly to 48%in two TCP traffic.

关键词： Software-defined network controller flow management

Model Predictive Control Strategy for residential Battery Energy Storage System in Volatile Electricity Market with Uncertain Daily Cycling Load

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Journal of Modern Power Systems and Clean Energy 2023年第2期11卷 534-543页

作者： Dejan P.Jovanović Gerard f.Ledwich Geoffrey r.Walker Institute of Electrical and Electronic Engineers QueenslandAustralia School of Electrical Engineering&robotics Queensland University of TechnologyBrisbaneAustralia

This paper presents a control strategy for residential battery energy storage systems,which is aware of volatile electricity markets and uncertain daily cycling *** economic benefits of energy trading for prosumers are achieved through a novel modification of a conventional model predictive control(MPC).The proposed control strategy guarantees an optimal global solution for the applied control action.A new cost function is introduced to model the effects of volatility on customer benefits more ***,the newly presented cost function models a probabilistic relation between the power exchanged with the grid,the net load,and the electricity *** probabilistic calculation of the cost function shows the dependence on the mathematical expectation of market price and net *** techniques for calculating this value are *** proposed strategy differs from the stochastic and robust MPC in that the cost is calculated across the market price and net load variations rather than across model constraints and parameter variations.

关键词： Optimal control model predictive control(MPC) energy market nonlinear constrained optimization revenue for battery energy storage system Gaussian mixture model autoregressive integrated moving average model

Study of Transition from Laminar to Turbulent Boundary Layer on a Tilted flat Plate Using Heat Transfer Measurements

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Journal of Thermal Science 2007年第2期16卷 186-191页

作者： E.Sanz C.Nicot r.Point f.Plaza Laboratoire de Mécanique des fluides et Acoustique LMFA(ECL-UCB-INSA Lyon-CNRS)36Avenue Guy de Collongue69134 Ecully.France.

The boundary layer transition over a flat tilted plate has been studied by means of heat transfer measurements. A heat flux sensor has been developed, in order to measure the efficiency of convective heat transfer for various types of surfaces or flows. Its operation at constant temperature allows direct and fast measurements of heat flux. The present paper reports the development of the sensor and presents its application to the study of transition in a boundary layer depending on the angle of incidence of the external flow. An exponential relationship between critical reynolds number and pressure gradient parameter has been found.

关键词： convective heat flux boundary layer transition pressure gradient.

Stress distribution from railway track over geogrid reinforced ballast underlain by clay

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Earthquake Engineering and Engineering Vibration 2019年第1期18卷 77-93页

作者： Mohammed Y.fattah Mahmood r.Mahmood Mohammed f.Aswad Civil Engineering Department University of TechnologyBaghdad Iraq Civil Engineering Department University of TechnologyBaghdad IraqAssistant

railway ballast forms a major component of a conventional rail track and is used to distribute the load to the subgrade, providing a smooth running surface for trains. It plays a significant role in providing support for the rail track base and distributing the load to the weaker layer underneath. Ballast also helps with drainage, which is an important factor for any type of transportation structure, including railroads. Over time, ballast progressively deforms and degrades under dynamic loading and loses its strength. In this study, extensive laboratory tests were conducted to investigate the effect of load amplitude, geogrid position, and number of geogrid layers, thickness of ballast layer and clay stiffness on the behavior of the reinforced ballast layer and induced strains in a geogrid. A half full-scale railway was constructed for carrying out the tests, which consisted of two rails 800 mm in length with three wooden sleepers(900 mm × 10 mm × 10 mm). Three ballast thicknesses of 200, 300 and 400 mm were used in the tests. The ballast was overlying 500 mm thickness clay in two states, soft and stiff. The tests were carried out with and without geogrid reinforcement; the tests were performed in a well-tied steel box of 1.5 m length ×1 m width ×1 m height. Laboratory tests were conducted to investigate the response of the ballast and the clay layers where the ballast was reinforced by a geogrid. Settlement in ballast and clay, soil pressure and pore water pressure induced in the clay were measured in reinforced and unreinforced ballast cases. It was concluded that the amount of settlement increased as the simulated train load amplitude increased, and there was a sharp increase in settlement up to cycle 500. After that, there was a gradual increase that leveled out between, 2500 to 4500 cycles depending on the frequency used. There was a slight increase in the induced settlement when the load amplitude increased from 0.5 to 1 ton but it was higher when the load am

关键词： ballast geogrid reinforcement clay stress pore water pressure dynamic load

Colloidal nanocrystals:Viable model systems for electronic quantum materials?

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Nano research 2024年第12期17卷 10511-10524页

作者： Jara f.Vliem Jesper r.Moes Ingmar Swart Daniel Vanmaekelbergh Debye Institute for Nanomaterials Science Department of ChemistryUniversity of Utrecht3584 CS Utrechtthe Netherlands

The field of colloidal nanocrystals has witnessed enormous progress in the last three *** many families of nanocrystals,wet-chemical syntheses have been developed that allow control over the crystal shape and dimensions,from the three-dimensional down to the zero-dimensional ***,careful control of surface chemistry has enabled the prevention of non-radiative recombination,thus allowing the detailed study of confined charge carriers and *** has led to a vast amount of applications of nanocrystals in displays,labels,and ***,we discuss how this expertise could benefit the rapidly advancing field of quantum materials,where the coherence of electronic wave functions is *** demonstrate that colloidal two-dimensional nanocrystals can serve as excellent model systems for studying topological phase transitions,particularly in the case of quantum spin Hall and topological crystalline *** aim to inspire researchers with strong chemical expertise to explore the exciting field of quantum materials.

关键词： colloidal nanocrystals topological insulators quantum materials edge/surface states

reconstruction of lithofacies using a supervised Self-Organizing Map:Application in pseudo-wells based on a synthetic geologic cross-section

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Artificial Intelligence in Geosciences 2024年第1期5卷 14-26页

作者： Carreira V.r. Bijani r. Ponte-Neto C.f. Departamento de Geologia e Geofísica Universidade Federal Fluminense(UFF)NiteróiBrazil Coordenação de Geofísica Observatório Nacional(ON-MCTIC)Rio de JaneiroBrazil

recently,machine learning(ML)has been considered a powerful technological element of different society *** transform the computer into a decision maker,several sophisticated methods and algorithms are constantly created and *** geophysics,both supervised and unsupervised ML methods have dramatically contributed to the development of seismic and well-log data *** well-logging,ML algorithms are well-suited for lithologic reconstruction problems,once there is no analytical expressions for computing well-log data produced by a particular rock ***,supervised ML methods are strongly dependent on a accurate-labeled training data-set,which is not a simple task to achieve,due to data absences or *** an adequate supervision is performed,the classification outputs tend to be more accurate than unsupervised *** work presents a supervised version of a Self-Organizing Map,named as SSOM,to solve a lithologic reconstruction problem from well-log ***,we go for a more controlled problem and simulate well-log data directly from an interpreted geologic *** then define two specific training data-sets composed by density(rHOB),sonic(DT),spontaneous potential(SP)and gamma-ray(Gr)logs,all simulated through a Gaussian distribution function per *** the training data-set is created,we simulate a particular pseudo-well,referred to as classification well,for defining controlled *** one comprises a training data-set with no labeled log data of the simulated fault *** the second test,we intentionally improve the training data-set with the *** bespeak the obtained results for each test,we analyze confusion matrices,logplots,accuracy and *** from very thin layer misclassifications,the SSOM provides reasonable lithologic reconstructions,especially when the improved training data-set is considered for *** set of numerical experiments shows that our SSOM is extremely

关键词： Self-Organizing Maps Supervised machine learning Synthetic well-log data Classification of lithofacies

A Geometric Distortion Solution Specifically for Historical Observations and its Implementation

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research in Astronomy and Astrophysics 2024年第11期24卷 85-94页

作者： f.r.Lin Q.Y.Peng Z.J.Zheng B.f.Guo School of Software Jiangxi Normal UniversityNanchang 330022China Sino-french Joint Laboratory for Astrometry Dynamics and Space ScienceJinan UniversityGuangzhou 510632China Department of Computer Science Jinan UniversityGuangzhou 510632China Guangdong Ocean University Zhanjiang 524000China

Geometric distortion(GD)critically constrains the precision of *** well-established methods to correct GD requires calibration observations,which can only be obtained using a special dithering strategy during the observation ***,this special observation mode is not often used,especially for historical observations before those GD correction methods were *** a result,some telescopes have no GD calibration observations for a long period,making it impossible to accurately determine the GD *** limits the value of the telescope observations in certain astrometric scenarios,such as using historical observations of moving targets in the solar system to improve their *** investigated a method for handling GD that does not rely on the calibration *** this advantage,it can be used to solve the GD models of telescopes which were intractable in the *** method was implemented in Python and released on *** was then applied to solve GD in the observations taken with the 1 m and 2.4 m telescopes at Yunnan *** resulting GD models were compared with those obtained using well-established methods to demonstrate the ***,the method was applied in the reduction of observations for two targets,the moon of Jupiter(Himalia)and binary GSC 2038-0293,to show its *** GD correction,the astrometric results for both targets show ***,the mean residual between the observed and computed position(O-C)for binary GSC 2038-0293 decreased from 36 to 5 mas.

关键词： astrometry-methods data analysis-techniques image processing

Stability of plane-parallel flow of magnetic fluids under external magnetic fields

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Applied Mathematics and Mechanics(English Edition) 2022年第2期43卷 295-310页

作者： P.Z.S.PAZ f.r.CUNHA Y.D.SOBrAL Department of Mathematics University of BrasíliaCampus Universitário Darcy RibeiroBrasília-DF70910-900Brazil Laboratory of Microhydrodynamics and rheology-Vortex Group Department of Mechanical EngineeringUniversity of BrasíliaCampus Universitário Darcy RibeiroBrasília-DF70910-900Brazil

In this work,we present a theoretical study on the stability of a two-dimensional plane Poiseuille flow of magnetic fluids in the presence of externally applied magnetic *** fluids are assumed to be incompressible,and their magnetization is coupled to the flow through a simple phenomenological *** parameters are defined,and the equations are perturbed around the base *** eigenvalues of the linearized system are computed using a finite difference scheme and studied with respect to the dimensionless parameters of the *** examine the cases of both the horizontal and vertical magnetic *** obtained results indicate that the flow is destabilized in the horizontally applied magnetic field,but stabilized in the vertically applied *** characterize the stability of the flow by computing the stability diagrams in terms of the dimensionless parameters and determine the variation in the critical reynolds number in terms of the magnetic ***,we show that the superparamagnetic limit,in which the magnetization of the fluids decouples from hydrodynamics,recovers the same purely hydrodynamic critical reynolds number,regardless of the applied field direction and of the values of the other dimensionless magnetic parameters.

关键词： hydrodynamic stability magnetic fluid Orr-Sommerfeld equation magnetization evolution