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Reduced chemistries with the Quantemol database (QDB)

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Plasma Science and Technology 2019年第6期21卷 38-51页

作者： Adetokunbo AYILARAN Martin HANICINEC sebastian MOHR Jonathan TENNYSON Quantemol Ltd 320 City Rd London EC1V 2NZ United Kingdom Department of Physics and Astronomy University College London London WC1E 6BT United Kingdom

Typical feed gas mixtures used in technological and other plasmas may give rise to reaction networks involving several hundred *** chemistries are often too large to be used in full reactor simulations and it is therefore desirable to construct reduced chemistry networks which mimic as closely as possible the behavior of the full chemistry but employ far fewer individual reactions and *** chemistries are available from the Quantemol database (QDB) and two approaches to constructing reduced chemistry from these chemistries based on (a) physical intuition and (b) sensitivity analysis of dominant reaction pathways,are *** doing this it is necessary to consider different pressure and power *** chemistry sets are presented for CF4/O2/N2/H2,for which 396 reactions and 52 species are reduced to 71 reactions and 26 species,and for pure O2,for which 45 reactions and 10 species are reduced to 34 reactions.

关键词： plasma chemistries quantemol database chemical reactions chemistry reduction stoichiometry

A COMPARATIVE STUDY OF THE INVENTORY SYSTEM WITH SERVICE FACILITY AND POSTPONED DEMANDS

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Journal of Systems Science and Systems Engineering 2014年第2期23卷 176-195页

作者： J.sebastian Arockia Jenifer B.Sivakumar School of Mathematics Madurai Kamaraj University

In this article, we present a continuous review （s,S） inventory system with a service facility consisting of finite buffer （capacity N ） and a single server. The customers arrive according to a Poisson process. The individual customer＇s unit demand is satisfied after a random time of service, which is assumed to be exponential. When the inventory level drops to s＇an order for Q（= S-s） items is placed. The lead time of reorder is assumed to be exponential distribution. An arriving customer, who finds the buffer is full, enters into the pool of infinite size or leaves the system according to a Bernolli trial. At the time of service completion, if the buffer size drops to a preassigned level L （1 〈 L 〈 N） or below and the inventory level is above s, we select the customers from the pool according to two different policy ： in first policy, with probability p （0 〈 p 〈 1） we select the customer from the head of the pool and we place the customer at the end of the buffer; in the second policy, with p （0 〈 p 〈 1） the customer from the pool is transferred to the buffer for immediate service and after completion of his service we provide service to the customer who is in the buffer with probability one. If at a service completion epoch the buffer turns out to be empty, there is at least one customer in the pool and the inventory level is positive, then the one ahead of all waiting in the pool gets transferred to the buffer, and his service starts immediately. The joint probability distribution of the number of customers in the pool, number of customers in the buffer and the inventory level is obtained in the steady-state case. Various stationary system performance measures are computed and total expected cost rate is calculated. A comparative result of two models is illustrate numerically.

关键词： Continuous review inventory system postponed demands service facility finite waiting hall pool with infinite size

A phononic rectifier based on carbon schwarzite host–guest system

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Chinese Physics B 2020年第12期29卷 50-55页

作者： Zhongwei Zhang Yulou Ouyang Jie Chen sebastian Volz Center for Phononics and Thermal Energy Science School of Physics Science and EngineeringTongji UniversityShanghai 200092China China-EU Joint Laboratory for Nanophononics Tongji UniversityShanghai 200092China Institute of Industrial Science The University of TokyoTokyo 153-8505Japan Laboratory for Integrated Micro and Mechatronic Systems CNRS-IIS UMI 2820The University of TokyoTokyo 153-8505Japan

Thermal rectification is a promising way to manipulate the heat flow,in which thermal phonons are spectrally and collectively *** phononic devices are mostly relying on monochromatic phonons,in this work we propose a phononic rectifier based on the carbon schwarzite host–guest *** using molecular dynamic simulations,we demonstrate that the phononic rectification only happens at a specific frequency of the hybridized mode for the host–guest system,due to its strong confinement ***,a significant rectification efficiency,~134%,is observed,which is larger than most of the previously observed *** study of length and temperature effects on the phononic rectification shows that the monochromaticity and frequency of the rectified thermal phonons depend on the intrinsic anharmonicity of the host–guest system and that the on-center rattling configuration with weak anharmonicity is *** study provides a new perspective on the rectification of thermal phonons,which would be important for controlling monochromatic thermal phonons in phononic devices.

关键词： thermal rectification phonon thermal transport

Multi-material additive manufacturing-functionally graded materials by means of laser remelting during laser powder bed fusion

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Frontiers of Mechanical Engineering 2023年第4期18卷 183-193页

作者： Alexander SCHMIDT Felix JENSCH sebastian HÄRTEL Chair of Hybrid Manufacturing Brandenburg University of TechnologyCottbus 03046Germany

Many processes may be used for manufacturing functionally graded *** them,additive manufacturing seems to be predestined due to near-net shape manufacturing of complex geometries combined with the possibility of applying different materials in one *** adjusting the powder composition of the starting material layer by layer,a macroscopic and step-like gradient can be *** further improve the step-like gradient,an enhancement of the in-situ mixing degree,which is limited according to the state of the art,is *** this paper,a novel technique for an enhancement of the in-situ material mixing degree in the melt pool by applying laser remelting(LR)is *** effect of layer-wise LR on the formation of the interface was investigated using pure copper and low-alloy steel in a laser powder bed fusion *** cross-sectional selective electron microscopic analyses were carried *** applying LR,the mixing degree was enhanced,and the reaction zone thickness between the materials was ***,an additional copper and iron-based phase was formed in the interface,resulting in a smoother gradient of the chemical composition than the case without *** Marangoni convection flow and thermal diffusion are the driving forces for the observed effect.

关键词： multi-material additive manufacturing(MMAM) functionally graded materials(FGMs) laser powder bed fusion(L-PBF) laser remelting(LR) pure copper

Effect of Different Calcination Temperatures and Post Annealing on the Properties of Acetic Acid Based Sol-Gel (Na_(0.5)K_(0.5))NbO_3(NKN) Thin Films

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Journal of Materials Science & Technology 2013年第2期29卷 142-148页

作者： sebastian Wiegand Stefan Flege Olaf Baake Wolfgang Ensinger Materials Analysis Group Department of Materials and Geosciences Technische Universitt Darmstadt Petersenstrasse 23 64287 Darmstadt Germany

（Na0.5K0.5）NbO3 （NKN） lead free thin films were synthesized by means of an acetic acid based sol-gel process on Pt/Ti/SiO2/Si substrates. Na-acetate, K-acetate and Nb-pentaethoxide were used as metal precursors and acetic acid as the solvent. The effect of different calcination temperatures on the properties of the NKN films was investigated by X-ray diffraction, scanning electron microscopy, leakage current and hysteresis measurements. Low calcination temperatures led to low currents at high electric fields whereas high calcination temperatures led to low currents at low electric fields. Based on these findings calcination at low temperature was combined with a post annealing treatment. Low leakage currents of 4×10^-4 A/cm2 at 150 kV/cm and 2Pr and 2Ec values of 28 μC/cm2 and 150 kV/cm, respectively, could be obtained. All films were single phase NKN with random crystal orientations and no crack or pore formation was visible on the surface.

关键词： Sol-gel process (Na0.5K0.5)NbO3 Thin film Perovskite Lead-free Piezo material

Synthesis and Characterization of(Na_(0.5)K_(0.5))NbO_3(NKN) Thin Films Formed by a Diol-based Sol-gel Process

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Journal of Materials Science & Technology 2012年第6期28卷 500-505页

作者： sebastian Wiegand Stefan Flege Olaf Baake Wolfgang Ensinger Technische Universitt Darmstadt Department of Materials and GeosciencesMaterials Analysis GroupPetersenstrasse 2364287 DarmstadtGermany

Lead-free （***0.5）Nb03 （NKN） thin films were fabricated by spin coating on Pt/Ti/SiO2/Si substrates by a diol-based sol-gel process. Na-acetate, K-acetate, Nb-pentaethoxide and 1,3 propanediol were used to prepare the NKN precursor solution. Thermal analysis showed two characteristic temperatures of 360 and 600℃. Based on these temperatures, a heat treatment program with pyrolysis at 360℃ and calcination at 600℃ after every layer was used. To avoid inhomogeneities and secondary phases, an excess of sodium and potassium was necessary. To evaluate the proper excess amount of sodium and potassium secondary ion mass spectrometry （SIMS） lateral element maps and X-ray diffraction （XRD） patterns were recorded. An excess amount of 20% led to homogeneous distribution of the elements and to single phase perovskite NKN films with random crystal orientation. Scanning electron microscopy （SEMI images showed a pore free surface with 100 nm grains. The leakage current measurements showed a current of lx10-3 A/cm2 at 150 kV/cm.

关键词： Sol-gel process (Nao.sK0.5)NbO3 Thin film Perovskite Lead-free Piezo material

Computational studies on the seismic response of the State Route 99 bridge in Seattle with SMA/ECC plastic hinges

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Frontiers of Structural and Civil Engineering 2019年第1期13卷 149-164页

作者： Jiping GE M.Saiid SAIIDI sebastian VARELA School of Urban Construction and Safety Engineering Shanghai Institute of TechnologyShanghai 201418China Department of Civil and Environmental Engineering University of NevadaRenoNV 89557USA Structural Engineering Group Freese and Nichols Inc.Fort WorthTX 76109USA

This paper reports a computational study on the seismic response of a three-span highway bridge system incorporating conventional and novel substructure details for improved seismic *** bridge has three continuous spans supported by two single-column piers and integral abutments founded on drilled *** will be the first full-scale highway bridge to use superelastic shape memory alloy bars (SMA)and engineered cementitious composite (ECC)to mitigate column plastic hinge damage and minimize residual displacements after a strong earthquake. A three-dimensional computational model capturing the nonlinear constitutive response of the novel materials and the effects of dynamic soil-structure interaction was developed to assess the seismic response of the bridge in finite-element software *** versions of the same bridge were analyzed and compared,one with conventional cast-in-place reinforced concrete columns,and the other with top plastic hinges incorporating Nickel-Titanium (NiTi)SMA reinforcing bars and *** novel SMA/ECC plastic hinges were found to substantially reduce damage and post-earthquake residual displacements in the bridge substructure,but led to larger maximum drifts relative to the bridge with conventional reinforced concrete plastic *** analysis results suggested that the novel plastic hinges could lead to improved post-earthquake serviceability of bridges after intense earthquakes.

关键词： seismic design analytical simulation near-fault earthquakes shape memory alloy engineered cementitious composite self-centering

First Record of the Gekkonid Genus Cnemaspis Strauch, 1887 from Gunung Mulu National Park, Northern Sarawak, East Malaysia may Represent an Undescribed Species

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Asian Herpetological Research 2014年第3期5卷 209-212页

作者： André KOCH sebastian SCHULZ Zoological Research Museum Alexander Koenig (ZFMK) Leibniz-Institute for terrestrial Biodiversity

We provide confirmed photographic evidence for the previously overlooked occurrence of the polyphyletic Asian gecko genus Cnemaspis from Gunung Mulu National Park, the world-renowned UNESCO natural heritage site in northern Sarawak, East Malaysia. This new record from Sarawak province represents a remarkable range extension for Cnemaspis cf. kendallii by 550 km to the northeast and denotes the most northern occurrence of the genus in Borneo. Our new finding makes it very likely that these gekkonid lizards also inhabit appropriate limestone karst habitats in adjacent Sabah, Brunei, and Kalimantan. Given the visible differences in the Mulu specimen compared to those from the remaining distribution range on Borneo and the Malaysian Peninsula together with the fact that numerous Cnemaspis species are restricted to small areas, it seems plausible that another undescribed, rather cryptic and possibly locally endemic Bornean species is involved. Lastly, the new record contributes to the importance of the Mulu National Park as a major conservation area in East Malaysia of international concerns.

关键词： Southeast Asia Borneo Gekkonidae herpetofaunal diversity new record

Laser-induced thermal lens study of the role of morphology and hydroxyl group in the evolution of thermal diffusivity of copper oxide

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Chinese Physics B 2021年第6期30卷 588-593页

作者： Riya sebastian M S Swapna Vimal Raj S Sankararaman Department of Optoelectronics University of KeralaTrivandrum 695581KeralaIndia

The paper explores the evolution of thermal behavior of the material by studying the variations in thermal diffusivity using the single beam thermal lens(TL) technique. For this purpose, the decomposition of Cu(OH)_(2) into CuO is studied in a time range up to 120 h, by subjecting the sample to morphological, structural, and spectroscopic characterizations. The time evolution of thermal diffusivity can be divided into three regions for demonstrating the dynamics of the reaction. When the reaction is complete, the thermal diffusivity is also found to be saturated. In addition to the morphological modifications,from rods to flakes, the variations in the amount of hydroxyl group are attributed to be responsible for the enhancement of base fluid's thermal diffusivity by 165%. Thus the study unveils the role of hydroxyl groups in the thermal behavior of CuO.

关键词： thermal diffusivity CuO thermal lens morphology hydroxyl group