scholarly journals Three-Dimensional Reconstruction of Ocean Circulation from Coastal Marine Observations: Challenges and Methods

2019 ◽  
Author(s):  
Ivan Manso-Narvarte ◽  
Erick Fredj ◽  
Gabriel Jordà ◽  
Maristella Berta ◽  
Annalisa Griffa ◽  
...  
Keyword(s):  
Ocean Circulation ◽  
Three Dimensional ◽  
Least Square ◽  
Optimal Interpolation ◽  
Least Squares Regression ◽  
Spatial Covariance ◽  
Depth Level ◽  
Subsurface Layers ◽  
Set Up

Abstract. Monitoring and investigating the dynamics of coastal currents is crucial for the development of environmentally sustainable coastal activities, in order to preserve marine ecosystems as well as to support marine and navigation safety. This need is driving the set-up of a growing number of multiplatform operational observing systems, aiming to the continuous monitoring of the coastal ocean. A significant percent of the existing observatories is today equipped with land-based High Frequency Radars (HFR), which provide real-time currents with unprecedent coverage and resolution, limited however, to the surface layer. The combination of data from HFR with complementary data from in-situ platforms providing information of the currents at subsurface layers (ADCP moorings) is investigated here to reconstruct the 3D current velocity field from in-situ observations. For this purpose, two methods based on different approaches are used. On the one hand, the Reduced Order Optimal Interpolation which is fed, in this case, with a spatial covariance matrix extracted from a realistic numerical oceanic simulation; and on the other hand, the Discrete Cosine Transform Penalized Least Square, which is a data gap-filling method based on penalized least squares regression that balances fidelity to the data and smoothness of the solution. As a proof of concept, we test the methods’ skills by using emulated observations of currents, extracted from a numerical simulation (3D reference field). The test set-up emulates the real observatory scenario in the study area (south-eastern Bay of Biscay), which includes a long-range HFR and two ADCP moorings inside the HFR footprint area. Then, the reconstructed fields (outputs of the methods) are compared with the 3D reference fields. In general, the results show satisfactory 3D reconstructions with mean spatial (for each depth level) errors between 0.55–10.94 cm s−1 for the first 150 m depth. The methods perform better in well sampled areas, and although different performances between the methods are observed, both show promising skills for the computation of new operational products integrating complementary observations, broadening the applications of in-situ observational data.

Exploring Nature's plasticity with a flexible probing tool, and finding new ways for its electronic distribution

2002 ◽  
Vol 30 (2) ◽  
pp. 78-82 ◽  
Author(s):  
M. Beier ◽  
M. Baum ◽  
H. Rebscher ◽  
R. Mauritz ◽  
A. Wixmerten ◽  
...  
Keyword(s):  
Three Dimensional ◽  
In Situ Synthesis ◽  
Light Modulation ◽  
Genomic Assays ◽  
Electronic Distribution ◽  
Spatial Light Modulation ◽  
Microarray Fabrication ◽  
Set Up ◽  
Microarray Format

Concepts and results are described for the use of a single, but extremely flexible, probing tool to address a wide variety of genomic questions. This is achieved by transforming genomic questions into a software file that is used as the design scheme for potentially any genomic assay in a microarray format. Microarray fabrication takes place in three-dimensional microchannel reaction carriers by in situ synthesis based on spatial light modulation. This set-up allows for maximum flexibility in design and realization of genomic assays. Flexibility is achieved at the molecular, genomic and assay levels. We have applied this technology to expression profiling and genotyping experiments.

In Situ Visualization of Layer Transitions during Convective Self-Assembly in a Sessile Drop

2007 ◽  
Vol 31 ◽  
pp. 117-119
Author(s):  
Li Gao ◽  
Qing Feng Yan ◽  
C.C. Wong ◽  
Yet Ming Chiang
Keyword(s):  
Self Assembly ◽  
Sessile Drop ◽  
Three Dimensional ◽  
Colloidal Crystals ◽  
Layer Transition ◽  
Simple Method ◽  
Colloidal Spheres ◽  
In Situ Visualization ◽  
Set Up

Convective self-assembly of colloidal spheres provides a simple method for fabricating two and three dimensional colloidal crystals. In this work, we investigated the layer transitions phenomena during colloidal self-assembly in a sessile drop by using an in-situ videoscopic set-up. The effects of surface charge, colloidal concentration, and surfactant additions were examined. The results show that the chemical environment plays an important role in colloidal self-assembly. In the case of ordered growth, different layer transition phenomena were observed when the colloidal concentration is different.

scholarly journals Obstacles and benefits of the implementation of a reduced rank smoother with a high resolution model of the Atlantic ocean

2012 ◽  
Vol 9 (2) ◽  
pp. 1187-1229 ◽  
Author(s):  
N. Freychet ◽  
E. Cosme ◽  
P. Brasseur ◽  
J.-M. Brankart ◽  
E. Kpemlie
Keyword(s):  
Atlantic Ocean ◽  
Ocean Circulation ◽  
Three Dimensional ◽  
Circulation Model ◽  
Point Of View ◽  
Optimal Interpolation ◽  
The North ◽  
Observation Network ◽  
North Brazil ◽  
Resolution Model

Abstract. Most of oceanographic operational centers use three-dimensional data assimilation schemes to produce reanalyses. We investigate here the benefits of a smoother, i.e. a four-dimensional formulation of statistical assimilation. A square-root sequential smoother is implemented with a tropical Atlantic ocean circulation model. A simple twin experiment is performed to investigate its benefits, compared to its corresponding filter. Results show that the smoother leads to a better estimation of the ocean state, both on statistical (i.e. mean error level) and dynamical point of view. Smoothed states are more in phase with the dynamics of the reference state, an aspect that is nicely illustrated with the chaotic dynamics of the north-Brazil rings. We also show that the smoother efficiency is strongly related to the filter configuration. One of the main obstacles to implement the smoother is then to accurately estimate the error covariances of the filter. Considering this, benefits of the smoother are also investigated with a configuration close to situations that can be managed by operational centers systems, where covariances matrices are fixed (optimal interpolation). We define here a simplified smoother scheme, called half-fixed basis smoother, that could be implemented with current reanalysis schemes. Its main assumption is to neglect the propagation of the error covariances matrix, what leads to strongly reduce the cost of assimilation. Results illustrate the ability of this smoother to provide a solution more consistent with the dynamics, compared to the filter. The smoother is also able to produce analyses independently of the observation frequency, so the smoothed solution appears more continuous in time, especially in case of a low frenquency observation network.

scholarly journals Obstacles and benefits of the implementation of a reduced-rank smoother with a high resolution model of the tropical Atlantic Ocean

Ocean Science ◽  
2012 ◽  
Vol 8 (5) ◽  
pp. 797-811
Author(s):  
N. Freychet ◽  
E. Cosme ◽  
P. Brasseur ◽  
J.-M. Brankart ◽  
E. Kpemlie
Keyword(s):  
Atlantic Ocean ◽  
Ocean Circulation ◽  
Three Dimensional ◽  
Circulation Model ◽  
Optimal Interpolation ◽  
Tropical Atlantic ◽  
Tropical Atlantic Ocean ◽  
The North ◽  
North Brazil ◽  
Resolution Model

Abstract. Most of oceanographic operational centers use three-dimensional data assimilation schemes to produce reanalyses. We investigate here the benefits of a smoother, i.e. a four-dimensional formulation of statistical assimilation. A square-root sequential smoother is implemented with a tropical Atlantic Ocean circulation model. A simple twin experiment is performed to investigate its benefits, compared to its corresponding filter. Despite model's non-linearities and the various approximations used for its implementation, the smoother leads to a better estimation of the ocean state, both on statistical (i.e. mean error level) and dynamical points of view, as expected from linear theory. Smoothed states are more in phase with the dynamics of the reference state, an aspect that is nicely illustrated with the chaotic dynamics of the North Brazil Current rings. We also show that the smoother efficiency is strongly related to the filter configuration. One of the main obstacles to implement the smoother is then to accurately estimate the error covariances of the filter. Considering this, benefits of the smoother are also investigated with a configuration close to situations that can be managed by operational center systems, where covariances matrices are fixed (optimal interpolation). We define here a simplified smoother scheme, called half-fixed basis smoother, that could be implemented with current reanalysis schemes. Its main assumption is to neglect the propagation of the error covariances matrix, what leads to strongly reduce the cost of assimilation. Results illustrate the ability of this smoother to provide a solution more consistent with the dynamics, compared to the filter. The smoother is also able to produce analyses independently of the observation frequency, so the smoothed solution appears more continuous in time, especially in case of a low frenquency observation network.

Closure of a Nuclear Waste Repository Deeply Imbedded in a Stratified Salt Bed

1994 ◽  
Vol 116 (4) ◽  
pp. 567-573 ◽  
Author(s):  
Wei Xu ◽  
Joseph Genin
Keyword(s):  
Triaxial Compression ◽  
Three Dimensional ◽  
Element Model ◽  
Nuclear Waste Repository ◽  
Relaxation Functions ◽  
Dimensional Finite Element ◽  
Set Up ◽  
The Stability ◽  
Three Dimensional Finite Element

The Waste Isolation Pilot Plant (WIPP) is a repository vault, mined deep into a salt strata. It eventually closes in on itself, encapsulating its contents. At room temperature salt may be regarded as a linear, isotropic, viscoelastic material. In this study, using triaxial compression test results on salt, we determine the relaxation functions and set up the boundary value problem for the encapsulation mechanism of a salt vault. Closure of the repository as a function of time is determined using a three-dimensional finite element model. The Tresca failure criterion is used to predict the stability of the repository. Finally, the study is validated by comparing our results to in-situ measured data.

In situ simultaneous measurement of stress, retardation, and three-dimensional refractive indexes during biaxial stretching experiments under various preheating times

2018 ◽  
Vol 38 (7) ◽  
pp. 703-713
Author(s):  
Kentaro Egoshi ◽  
Toshitaka Kanai ◽  
Kazuhiro Tamura
Keyword(s):  
Evaluation Method ◽  
Three Dimensional ◽  
Semicrystalline Polymers ◽  
Test Machine ◽  
Biaxial Stretching ◽  
Oriented Film ◽  
Set Up ◽  
Short Time ◽  
Stretching Process

Abstract An evaluation method for the stretchability of a biaxially oriented film during the stretching process was recently developed using an in situ measurement test machine. Stress, retardation, three-dimensional refractive indexes, light-scattering image, and birefringence distribution of films could be obtained in a short time. This stretching test machine was applied to examine the film stretchability of both semicrystalline polymers, such as polypropylene, and noncrystalline polymers, such as polystyrene, under various preheating times. From the measurements, the stress of semicrystalline polymers increased with increasing preheating times before stretching the film. However, the stress of noncrystalline polymers did not increase with increasing preheating times. This means that semicrystalline polymer is required to set up an optimum stretching condition of the preheating time for a satisfactory biaxially oriented film. Furthermore, the birefringence distribution and thickness uniformity of the stretched film were measured simultaneously. It was found that the stretchability of polypropylene and polystyrene films could be evaluated with a small piece of the sample using the biaxial stretching test machine.

scholarly journals A gridded European global dataset based on in-situ observations

2021 ◽  
Author(s):  
Gerard van der Schrier ◽  
Wouter Knap ◽  
Marieke Dirksen ◽  
Else J.M. van den Besselaar ◽  
Albert M.G. Klein Tank
Keyword(s):  
Sunshine Duration ◽  
Global Radiation ◽  
Radiant Energy ◽  
Optimal Interpolation ◽  
Control Procedure ◽  
Spatial Covariance ◽  
Data Set ◽  
Space And Time ◽  
Gridded Dataset

<p>Within the EOBS project, one of the objectives is to provide an (ensemble) gridded data set of global radiation. <em>In-situ</em> observations of daily sums of global radiation are combined with daily sunshine duration records to construct a dataset for daily global radiation that goes back to 1950. A generalization of the commonly used Angstrom-Prescott formula is used to relate daily values of sunshine duration to global radiation, where optimal values of the parameters in this model are found by allowing for variations in the latitude and with the seasons. A quality control procedure based on the physical limits of  global radiation - latitude and yearday dependent - is applied to the data.</p><p>Based on this dataset, a gridded dataset for daily global radiation is produced with a resolution of 0.1 degree, covering Europe. The density of the combined networks of radiation and sunshine duration measurements hugely varies in space and time and this inhomogeneity is likely to give variations in space and time of the confidence of the gridded dataset. A method for enhancing the spatial analysis of daily global radiation from a sparse network is by incorporating information on the spatial covariance in the global radiation fields determined from high‐resolution measurements available in the past. Here we use satellite-based daily observations of downwards surface shortwave radiation from the CERES (Clouds and the Earth's Radiant Energy System) dataset for this purpose.</p><p>This approach is inspired by the reduced space optimal interpolation (RSOI) method, and the dominant patterns of variability are calculated using Self Organizing Maps (SOMs). Before reducing the dimension of the CERES dataset to 15 patterns, seasonal trends were removed. SOMs comprise a class of unsupervised neural networks that organize input geospatial data into a user-defined number of outputs (nodes) obtained by iteratively adjusting the nodes to resemble the input data. The training of this unsupervised artificial neural network is entirely data driven.</p><p>In the presentation, the similarity between the gridded dataset and the underlying station data is quantified, and a comparison against the CMSAF SARAH dataset is presented.</p>

Study on the Online Ink Testing with CCD Based on Calabro-Mercatucci Model

2010 ◽  
Vol 174 ◽  
pp. 195-198
Author(s):  
Zhen Liu ◽  
Hua Yang
Keyword(s):  
Film Thickness ◽  
Three Dimensional ◽  
Least Square ◽  
Curved Surface ◽  
Surface Model ◽  
Printing Quality ◽  
Set Up ◽  
The Relationship ◽  
Black Color ◽  
Rgb Values

With the increasing of press’ speed and the people’s requirement, online testing of printed stock becomes to the development direction. The ink metering control is an important part of printing quality control. So this paper sets up a three-dimensional curved surface model of the CCD’s RGB values and the best ink film thicknesses based on Calabro-Mercatucci model, which can be applied to the online ink testing with CCD. Firstly, we printed cyan magenta yellow black color bitches of different ink film thicknesses and got their optical densities and RGB values with measuring tools. Afterwards, we got the parameters in Calabro-Mercatucci model with the experimental data through the least square algorithm and then got the scale of the best ink film thickness. Last, we set up the three-dimensional curved surface model of the CCD’s RGB values and the best ink film thicknesses through ‘v4’ algorithm in matlab tools. With this three-dimensional curved surface model, we can judge whether the thickness corresponding to the RGB values is in the range of the best ink film thickness. It is proved that this method can indicate the relationship between CCD’s RGB values and the ink film thickness and be applied to detect the ink metering after tested.

scholarly journals Support Technique of Horse Head in Weakly Cemented Soft Rock

2015 ◽  
Vol 9 (1) ◽  
pp. 852-856
Author(s):  
Li Haixia ◽  
Wang Zuhe ◽  
Xiu Yingchang ◽  
Wang Genxia
Keyword(s):  
Numerical Analysis ◽  
Three Dimensional ◽  
Soft Rock ◽  
In Situ Stress ◽  
Good Effect ◽  
Rock Composition ◽  
Head Surface ◽  
Set Up ◽  
Similar Good

Part of the chambers of the coalmine roadway in Western Inner Mongolia and Eastern Ningxia of China are in weakly consolidated soft rock formation. Taking the horse head engineering in Maiduoshan coal mine in the main level as an example, a new scheme was put forward to optimize the original supporting scheme. A three-dimensional numerical model of the project of horse head was set up. According to the rock composition, different layer has different material properties. Initial stress of the model was given according to the measure results of in-situ stress. Strain softening constitutive model was used in calculation. The mechanical softening of surrounding rock after excavation was studied by numerical analysis method. Numerical analysis was done before construction, and displacement of horse head surface was monitored in construction. The result of numerical analysis and the monitoring data are similar. Good effect has been achieved after the implementation of the project.

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