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The Role of Inertia and dissipation in the dynamics of the director for a Nematic Liquid Crystal Coupled with an Electric Field

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Communications in Computational Physics 2015年第6期18卷 147-166页

作者： peder a.rsa.d Johanna Ridder department of Mathematical Sciences Norwegian University of Science and TechnologyNO–7491 TrondheimNorway department of Mathematics University of OsloP.O.Box NO-1053BlindernOslo-0316Norway

We consider the dynamics of the director in a nematic liquid crystal when under the influence of an applied electric *** an energy variational approach we derive a dynamic model for the director including both dissipative and inertial forces.A numerical scheme for the model is proposed by extending a scheme for a related variational wave *** experiments are performed studying the realignment of the director field when applying a voltage difference over the liquid crystal *** particular,we study how the relative strength of dissipative versus inertial forces influence the time scales of the transition between the initial configuration and the electrostatic equilibrium state.

关键词： Nematic liquid crystals Freedericksz transition dynamics of director fields

Exploring and machine learning structural instabilities in 2d materials

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npj Computational Materials 2023年第1期9卷 2016-2025页

作者： Simone Manti Mark Kamper Svendsen Nikolaj R.Knøsgaard peder M.Lyngby Kristian S.Thygesen CAMd Computational Atomic-Scale Materials DesignDepartment of PhysicsTechnical University of Denmark2800 Kgs.LyngbyDenmark Center for Nanostructured Graphene(CNG) Department of PhysicsTechnical University of DenmarkDK-2800 Kongens LyngbyDenmark

We address the problem of predicting the zero-temperature dynamical stability (dS) of a periodic crystal without computing its fullphonon band structure. Here we report the evidence that dS can be inferred with good reliability from the phonon frequencies atthe center and boundary of the Brillouin zone (BZ). This analysis represents a validation of the dS test employed by theComputational 2d Materials database (C2dB). For 137 dynamically unstable 2d crystals, we displace the atoms along an unstablemode and relax the structure. This procedure yields a dynamically stable crystal in 49 cases. The elementary properties of these newstructures are characterized using the C2dB workflow, and it is found that their properties can differ significantly from those of theoriginal unstable crystals, e.g., band gaps are opened by 0.3 eV on average. All the crystal structures and properties are available inthe C2dB. Finally, we train a classification model on the dS data for 3295 2d materials in the C2dB using a representation encodingthe electronic structure of the crystal. We obtain an excellent receiver operating characteristic (ROC) curve with an area under thecurve (AUC) of 0.90, showing that the classification model can drastically reduce computational efforts in high-throughput studies.

关键词： structure unstable structural

dimension-Reduced Model for deep-Water Waves

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Journal of Applied Mathematics and Physics 2019年第1期7卷 72-92页

作者： Michael Bestehorn peder A. Tyvand Thomas Michelitsch department of Physics Brandenburg University of Technology Cottbus Germany department of Mathematical Sciences and Technology Norwegian University of Life Sciences &#197 s Norway CNRS Institut Jean le Rond d’Alembert Sorbonne Université Paris France

Starting from the 2d Euler equations for an incompressible potential flow, a dimension-reduced model describing deep-water surface waves is derived. Similar to the Shallow-Water case, the z-dependence of the dependent variables is found explicitly from the Laplace equation and a set of two one- dimensional equations in x for the surface velocity and the surface elevation remains. The model is nonlocal and can be formulated in conservative form, describing waves over an infinitely deep layer. Finally, numerical solutions are presented for several initial conditions. The side-band instability of Stokes waves and stable envelope solitons are obtained in agreement with other work. The conservation of the total energy is checked.

关键词： Hydrodynamics Ocean Waves deep-Water Waves Numerical Solutions Fractal derivatives

Identification of non-linear autoregressive models with exogenous inputs for room air temperature modelling

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能源与人工智能(英文) 2022年第3期9卷 78-87页

作者： Christian Ankerstjerne Thilker peder Bacher davide Cali Henrik Madsen Technical University of denmark Department of Applied Mathematics and Computer ScienceAsmussens AlléBuilding 303BDK-2800 Kgs.LyngbyDenmark

This paper proposes non-linear autoregressive models with exogenous inputs to model the air temperature ineach room of a danish school building connected to the local district heating network. To obtain satisfactorymodels, the authors find it necessary to estimate the solar radiation effect as a function of the time of the dayusing a B-spline basis expansion. Furthermore, this paper proposes a method for estimating the valve positionof the radiator thermostats in each room using modified Hermite polynomials to ensure monotonicity of theestimated curve. The non-linearities require a modification in the estimation procedure: Some parametersare estimated in an outer optimisation, while the usual regression parameters are estimated in an inneroptimisation. The models are able to simulate the temperature 24 h ahead with a root-mean-square-errorof the predictions between 0.25℃ and 0.6℃. The models seem to capture the solar radiation gain in away aligned with expectations. The estimated thermostatic valve functions also seem to capture the importantvariations of the individual room heat inputs.

关键词： Time series analysis Non-linear models district heating Smart energy systems

Human-driven topographic effects on the distribution of forest in a flat, lowland agricultural region

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Journal of Geographical Sciences 2014年第1期24卷 76-92页

作者： Mette V. OdGAARd peder K. BOCHER Tommy dALGAARd Jesper E. MOESLUNd Jens-Christian SVENNING department of Agroecology Aarhus University Blichers AIIe 20 DK-8830 Tjele Denmark Ecoinformatics & Biodiversity Group Department of Bioscience Aarhus University Ny Munkegade 114DK-8000 Aarhus C Denmark department of Computer Science Aarhus University Abogade 34 DK-8200 Aarhus N Denmark

Complex topography buffers forests against deforestation in mountainous regions. However, it is unknown if terrain also shapes forest distribution in lowlands where human impacts are likely to be less constrained by terrain. In such regions, if important at all, to- pographic effects will depend on cultural-historical factors and thus be human-driven （an- thropogenic） rather than natural, except in regions where the general climate or extreme soils limit the occurrence of forests. We used spatial regression modeling to assess the extent to which topographic factors explain forest distribution （presence-absence at a 48x48 m resolu- tion） in a lowland agricultural region （denmark, 43,075 km2） at regional and landscape scales （whole study area and 10x10 km grid cells, respectively）, how landscape-scale for- est-topography relationships vary geographically, and which potential drivers （topographic heterogeneity, forest cover, clay content, coastal/inland location） determine this geographic heterogeneity. Given a moist temperate climate and non-extreme soils all landscapes in denmark would naturally be largely forest covered, and any topographic relationships will be totally or primarily human-driven. At regional scale, topographic predictors explained only 5% of the distribution of forest. In contrast, the explanatory power of topography varied from 0%-61% at landscape scale, with clear geographic patterning. Explanatory power of topog- raphy at landscape scale was moderately dependent on the potential drivers, with topog- raphic control being strongest in areas with high topographic heterogeneity and little forest cover. However, these conditioning effects were themselves geographically variable. Our findings show that topography by shaping human land-use can affect forest distribution even in flat, lowland regions, but especially via localized, geographically variable effects.

关键词： Europe forest cover geographically weighted regression human impact landscape development topography vegetation distribution.

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RF4CE有何要求

今日电子 2009年第3期 44-45,49页

作者： peder Rand 德州仪器公司

消费电子射频（RF4CE）联盟是针对消费类电子产品遥控器的一种协议标准。松下、飞利浦、三星电子和索尼公司组成的企业联盟正在推动这一标准化进程。它们的目标是，通过运用于遥控器的双向RE通信实现高可靠性和众多新颖功能，从而向消... 详细信息

消费电子射频（RF4CE）联盟是针对消费类电子产品遥控器的一种协议标准。松下、飞利浦、三星电子和索尼公司组成的企业联盟正在推动这一标准化进程。它们的目标是，通过运用于遥控器的双向RE通信实现高可靠性和众多新颖功能，从而向消费者提供更多价值。

关键词：消费类电子产品企业联盟协议标准消费电子索尼公司三星电子高可靠性遥控器

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印刷色彩测量

广东印刷 1995年第2期 13-14页

作者： peder Nelson

每个人对颜色的感觉和演译方法都非常主观,而且跟别人不同的原因包括个人偏爱、年龄、眼睛疲劳及某些生理因素等,加上灯光环境的转变,在印刷房中很难准确、重复利用眼睛来控制及演译颜色。当同意运用颜色品质控制标准时,密度仪、色度仪... 详细信息

每个人对颜色的感觉和演译方法都非常主观,而且跟别人不同的原因包括个人偏爱、年龄、眼睛疲劳及某些生理因素等,加上灯光环境的转变,在印刷房中很难准确、重复利用眼睛来控制及演译颜色。当同意运用颜色品质控制标准时,密度仪、色度仪和分光光度仪将是理想的印刷色彩测量仪器,它们能够帮助节省金钱和物料,减低损耗及不合格货品的

关键词：印刷色彩分光光度三刺激值滤色镜仪器密度仪油墨叠印色度仪

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加拿大的MSAT（移动卫星）计划

电信快报 1992年第5期 1-5页

作者： peder.,A 王铮

How Raised Beds and Fe-Chelate Affect Soybean Iron deficiency Chlorosis and Yield

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Agricultural Sciences 2021年第7期12卷 755-768页

作者： Lucas C. Holmes Hans J. Kandel Grant H. Mehring peder K. Schmitz department of Plant Sciences North Dakota State University Fargo ND USA WestBred Bayer Crop Science Fargo North Dakota USA

Water-logging and the inability to take up sufficient iron (Fe), causing iron deficiency chlorosis (IdC) in soybean (Glycine max, L. Merr.), can be major yield reducing factors in certain soils in the northern USA and Manitoba, Canada, soybean growing regions. The objective of this research was to evaluate soybean IdC, biomass production, and yield with seeding on raised beds and seed application of the Fe-chelate compound ortho-ortho-Fe-EddHA. In six environments, soybean were seeded on raised beds and conventionally prepared seedbeds (flat) and with a factorial arrangement of five cultivars (within adapted maturity group 0.1 to 0.9 and variable IdC tolerance) and seed applied Fe-EddHA using rates of 0 kg·ha−1 and 3.36 kg·ha−1. There were no significant interactions between the factors tested. The plant population was 27% higher on the raised beds compared with flat, and yield was 6.3% higher (2893 kg·ha−1 vs. 2722 kg·ha−1). Total dry plant biomass on raised beds was 9.8% greater compared with flat. The plant population with seed applied Fe-EddHA was 10.6% lower compared with no application. However, the IdC score was significantly lower 2.2 vs 2.4 (1 = green, 5 = dead) for Fe-EddHA seed application. Yield and plant biomass we

关键词： Soybean Raised Beds Iron deficiency Chlorosis Fe-Chelate