A new model for flux emergence and the evolution of sunspots and the large-scale fields

Solar Physics ◽  
1985 ◽  
Vol 97 (1) ◽  
pp. 59-79 ◽  
Author(s):  
P. S. McIntosh ◽  
P. R. Wilson
Keyword(s):  
Large Scale ◽  
Flux Emergence ◽  
New Model

A new model order reduction method for the design of compensator by using moment matching algorithm

2019 ◽  
Vol 42 (3) ◽  
pp. 472-484 ◽  
Author(s):  
Arvind Kumar Prajapati ◽  
Rajendra Prasad
Keyword(s):  
Model Reduction ◽  
Lower Order ◽  
Large Scale ◽  
Order Reduction ◽  
Order System ◽  
Moment Matching ◽  
Matching Algorithm ◽  
New Model ◽  
Factor Division Algorithm ◽  
Lower Order System

The aim of this paper is the construction of a new model reduction technique for large scale stable linear dynamic systems. It is principally focused on the dominant modes and time moments retention. This reduction implicates the translation of the overall important features confined in the large scale complete order model into the lower order system, allowing the computation of approximant denominator by using generalized pole clustering method. The approximant numerator is obtained by means of the factor division algorithm. As a result, a lower order system is obtained. To demonstrate its effectiveness, to highlight some fundamental of its features, and to accomplish its accuracy, a comparative study is done. Two standard numerical examples are taken, where approximant model computed by the proposed method is compared with the reduced order models computed from the recently proposed methods as well as well-known model reduction schemes. The paper is also emphasized on the design of compensator by using moment matching algorithm with the help of the reduced model. The design of compensator is validated and illustrated with the help of a standard numerical example taken from the literature.

Application of a Hybrid RANS-LES CFD Methodology to Primary Atomization in a Coaxial Injector

2015 ◽  
Author(s):  
Wayne Strasser ◽  
Francine Battaglia ◽  
Keith Walters
Keyword(s):  
Large Scale ◽  
Liquid Core ◽  
Density Fluctuations ◽  
Momentum Balance ◽  
Stable Model ◽  
Source Terms ◽  
New Model ◽  
Rans Model ◽  
Mesh Resolution ◽  
Newtonian Liquids

Non-zonal hybrid RANS-LES models, i.e. those which do not rely on user-prescribed zones for activating RANS or LES, have shown promise in accurately resolving the energy-containing and highly anisotropic large-scale motions in complex separated flows. In particular, the recently proposed dynamic hybrid RANS-LES (DHRL) approach, a method which relies on the continuity of turbulence production through the RANS-to-LES transition zone, has been validated for several different compressible and incompressible single phase flow problems and has been found to be accurate and relatively insensitive to mesh resolution. Time-averaged source terms are used to augment the momentum balance. An added benefit of the DHRL is the ability to directly couple any combination of RANS and LES models into a hybrid model without any change to numerical treatment of the transition region. In this study, an attempt is made to extend the application of this model to multiphase flows using two open literature coaxial two-stream injectors involving non-Newtonian liquids. For the first time, the new model has been successfully implemented in a multiphase framework, combining the SST RANS model with MILES LES approach. Favre averaging is used to ensure consistency between the momentum equations and the density fluctuations. It was found that the momentum source terms must be density weighted in order to ensure stability of the solution. Primary atomization findings with a stable model are encouraging. The spray character with the new model was somewhere between that of a RANS model and the LES result. Droplet sizes, which are indicative of the shear layer energy, for the RANS model were greater than the hybrid results, which were comparable to the LES result and matched the experimental expectation. Additionally, the new approach showed a liquid core breakup length close to that expected from the literature.

scholarly journals A new model for the full shape of the large-scale power spectrum

2010 ◽  
Vol 408 (4) ◽  
pp. 2397-2412 ◽  
Author(s):  
Francesco Montesano ◽  
Ariel G. Sánchez ◽  
Stefanie Phleps
Keyword(s):  
Power Spectrum ◽  
Large Scale ◽  
New Model

1823 New Model of Wind Lens Applied to Large-Scale Wind Turbine

2008 ◽  
Vol 2008.2 (0) ◽  
pp. 167-168
Author(s):  
Yoshinori NAGAYAMA ◽  
Kazunari TAKATA ◽  
Yuji OHYA ◽  
Takashi KARASUDANI
Keyword(s):  
Wind Turbine ◽  
Large Scale ◽  
New Model

scholarly journals Recurrent flux emergence from dynamo-generated fields

2010 ◽  
Vol 6 (S271) ◽  
pp. 407-408
Author(s):  
Jörn Warnecke ◽  
Axel Brandenburg
Keyword(s):  
Magnetic Field ◽  
Time Series ◽  
Large Scale ◽  
Field Structure ◽  
Flux Emergence ◽  
Magnetic Field Structure ◽  
Forcing Function ◽  
Large Scale Magnetic Field ◽  
The Magnetic Field

Abstractwe investigate the emergence of a large-scale magnetic field. This field is dynamo-generated by turbulence driven with a helical forcing function. Twisted arcade-like field structures are found to emerge in the exterior above the turbulence zone. Time series of the magnetic field structure show recurrent plasmoid ejections.

Accelerate Convergence Rate of Distributed Consensus Algorithm with Optimized Topology

2014 ◽  
Vol 511-512 ◽  
pp. 950-953
Author(s):  
Huan Xin Peng ◽  
Wen Kai Wang ◽  
Bin Liu
Keyword(s):  
Convergence Rate ◽  
Large Scale ◽  
Nearest Neighbor ◽  
Consensus Algorithm ◽  
Algebraic Connectivity ◽  
Distributed Consensus ◽  
Consensus Algorithms ◽  
New Model ◽  
Accelerate Convergence ◽  
Topology Model

The convergence rate is very important in the distributed consensus problems, especially, for the distributed consensus algorithms based on large-scale complex networks. In order to accelerate the convergence rate of the distributed consensus algorithms, in the paper, we propose an optimized topology model by adding randomly a few shortcuts to the nearest neighbor coupling networks, and the shortcuts follow a normal distribution. By analyses and simulations, the results show that the algebraic connectivity of the new model is bigger than that of the NMW model, and the convergence rate of the distributed consensus based on the new model is higher than that based on the NMW model

Marketing tourists gazing into the tourism domain

2015 ◽  
Vol 9 (4) ◽  
pp. 417-422 ◽  
Author(s):  
Roger Marshall ◽  
Rouxelle De Villiers
Keyword(s):  
Alternative Model ◽  
Large Scale ◽  
Theory Development ◽  
Major Change ◽  
Story Telling ◽  
Content Type ◽  
New Model ◽  
Time Traveler ◽  
Academic Marketing ◽  
Practical Implications

Purpose – Urry’s model of Tourism Gaze as described by Woodside is problematic, in that tourist participant observers change the phenomenon they observe. The purpose of this study is to present an alternative model that better represents the dialectic between tourists and the destination culture. Design/methodology/approach – A story-telling technique, based upon personal experience and introspection that matches the story told by Woodside, is used to illustrate the theory development and formulate an alternative model. Findings – A new model is proposed that acknowledges that the more a tourist lives their tourism experience and becomes immersed in the destination culture, the greater the affect he/she has upon the destination. The issue of authenticity is discussed in relationship to this new model, as – in a sense – the experience of a one-time traveler is as authentic as those of a long-term stay tourist. Practical implications – The practical implications are both for tourist operators and policymakers. Cultures change, regardless of any tourism activity; but, such activity is a major change-agent, especially so as the emerging Asian countries discover the pleasures of “globe-trotting”. Although the cultural experience of tourists will remain authentic, large-scale tourism projects will inevitably change the culture the tourists sought to experience in the first place. The value of alternate tourism strategies based on the tourist’s impact upon the host culture is becoming increasingly critical. Originality/value – The new model is simple but effective, and is more pragmatic and accurate than the original tourist gaze model of Urry. The introspective, story-telling, methods used are more typical of academic marketing than tourism research, but serve the purpose here well by making the conceptual idea readily available to the reader.

scholarly journals The multi-scale aerosol-climate model PNNL-MMF: model description and evaluation

2010 ◽  
Vol 3 (4) ◽  
pp. 1625-1695 ◽  
Author(s):  
M. Wang ◽  
S. Ghan ◽  
R. Easter ◽  
M. Ovchinnikov ◽  
X. Liu ◽  
...  
Keyword(s):  
Reasonable Agreement ◽  
Large Scale ◽  
Climate Model ◽  
Cloud Microphysics ◽  
Chemical Processes ◽  
Future Climate Change ◽  
Free Troposphere ◽  
Microphysics Scheme ◽  
New Model ◽  
Multi Scale

Abstract. Anthropogenic aerosol effects on climate produce one of the largest uncertainties in estimates of radiative forcing of past and future climate change. Much of this uncertainty arises from the multi-scale nature of the interactions between aerosols, clouds and large-scale dynamics, which are difficult to represent in conventional global climate models (GCMs). In this study, we develop a multi-scale aerosol climate model that treats aerosols and clouds across different scales, and evaluate the model performance, with a focus on aerosol treatment. This new model is an extension of a multi-scale modeling framework (MMF) model that embeds a cloud-resolving model (CRM) within each grid column of a GCM. In this extension, the effects of clouds on aerosols are treated by using an explicit-cloud parameterized-pollutant (ECPP) approach that links aerosol and chemical processes on the large-scale grid with statistics of cloud properties and processes resolved by the CRM. A two-moment cloud microphysics scheme replaces the simple bulk microphysics scheme in the CRM, and a modal aerosol treatment is included in the GCM. With these extensions, this multi-scale aerosol-climate model allows the explicit simulation of aerosol and chemical processes in both stratiform and convective clouds on a global scale. Simulated aerosol budgets in this new model are in the ranges of other model studies. Simulated gas and aerosol concentrations are in reasonable agreement with observations, although the model underestimates black carbon concentrations at the surface. Simulated aerosol size distributions are in reasonable agreement with observations in the marine boundary layer and in the free troposphere, while the model underestimates the accumulation mode number concentrations near the surface, and overestimates the accumulation number concentrations in the free troposphere. Simulated cloud condensation nuclei (CCN) concentrations are within the observational variations. Simulated aerosol optical depth (AOD) and single scattering albedo (SSA) are in reasonable agreement with observations, and the spatial distribution of AOD is consistent with observations, while the model underestimates AOD over regions with strong fossil fuel and biomass burning emissions, and overestimates AOD over regions with strong dust emissions. Overall, this multi-scale aerosol climate model simulates aerosol fields as well as conventional aerosol models.

scholarly journals Explicit silicate cycling in the Kiel Marine Biogeochemistry Model, version 3 (KMBM3) embedded in the UVic ESCM version 2.9

2020 ◽  
Author(s):  
Karin Kvale ◽  
David P. Keller ◽  
Wolfgang Koeve ◽  
Katrin J. Meissner ◽  
Chris Somes ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Primary Production ◽  
Large Scale ◽  
Climate Model ◽  
Net Primary Production ◽  
Coupled Model ◽  
Co2 Concentration ◽  
Ecosystem Model ◽  
New Model ◽  
Fully Coupled

Abstract. We describe and test a new model of biological marine silicate cycling, implemented in the University of Victoria Earth System Climate Model (UVic ESCM) version 2.9. This new model adds diatoms, which are a key aspect of the biological carbon pump, to an existing ecosystem model. The new model performs well against important ocean biogeochemical indicators and captures the large-scale features of the marine silica cycle. Furthermore it is computationally efficient, allowing both fully-coupled, long-timescale transient simulations, as well as "offline" transport matrix spinups. We assess the fully-coupled model against modern ocean observations, the historical record since 1960, and a business-as-usual atmospheric CO2 forcing to the year 2300. The model simulates a global decline in net primary production (NPP) of 1.3 % having occurred since the 1960s, with the strongest declines in the tropics, northern mid-latitudes, and Southern Ocean. The simulated global decline in NPP reverses after the year 2100 (forced by the extended RCP CO2 concentration scenario), and NPP returns to pre-industrial rates by 2300. This recovery is dominated by increasing primary production in the Southern Ocean, mostly by calcifying phytoplankton. Large increases in calcifying phytoplankton in the Southern Ocean offset a decline in the low latitudes, producing a global net calcite export in 2300 that varies only slightly from pre-industrial rates. Diatoms migrate southward in our simulations, following the receding Antarctic ice front, but are out-competed by calcifiers across most of their pre-industrial Southern Ocean habitat. Global opal export production thus drops to 50 % of its pre-industrial value by 2300. Model nutrients phosphate, silicate, and nitrate build up along the Southern Ocean particle export pathway, but dissolved iron (for which ocean sources are held constant) increases in the upper ocean. This different behaviour of iron is attributed to a reduction of low-latitude NPP (and consequently, a reduction in both uptake and export and particle, including calcite, scavenging), an increase in seawater temperatures (raising the solubility of particle forms), and stratification that "traps" the iron near the surface. These results are meant to serve as a baseline for sensitivity assessments to be undertaken with this model in the future.

scholarly journals System transformation in palliative and end of life care: developing a model for excellence

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Alistair Hewison ◽  
Emma Hodges ◽  
Sundaravadivel Balasubramanian ◽  
Tina Swani
Keyword(s):  
End Of Life ◽  
End Of Life Care ◽  
Large Scale ◽  
Scale Transformation ◽  
Life Care ◽  
System Transformation ◽  
Content Type ◽  
New Model ◽  
Care Community ◽  
Care Services

PurposeThe purpose of this study is to report how the palliative and end of life care community in one region of England worked together to create a new model for integrated palliative and end of life care to respond to the challenges of changing demography, the need to reduce unnecessary hospital admissions of people nearing the end of life and to improve the quality of provision in line with current policy.Design/methodology/approachA co-production approach to system transformation was adopted involving 73 members of the palliative and end of life care community in one region of England.FindingsA new model for the delivery of integrated palliative and end of life care services was produced. The breadth of membership of the co-production working party and constructive/collaborative working helped ensure a viable model was produced.Practical implicationsAlthough systems’ thinking perspectives can help address the challenges of large-scale transformation because they focus on promoting the value of relationships, recognise the nuances of context and the need to understand system behaviour over time, the potential for systems to benefit from this approach is limited by the complexity of the processes involved and the sheer number of issues to be addressed in practical terms by policy makers and change leaders.Originality/valueThe paper explores the contribution that theories of large-scale transformation can make to the design of palliative and end of life care services in health and social care.

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