Spatial Model for Corrosion in Ships and FPSOs

2014 ◽  
Author(s):  
Jesus Luque ◽  
Rainer Hamann ◽  
Daniel Straub
Keyword(s):  
Spatial Variability ◽  
Spatial Dependence ◽  
Measurement Data ◽  
Corrosion Process ◽  
Plate Element ◽  
Structural Element ◽  
Operational Conditions ◽  
Spatial Random Field ◽  
Spatio Temporal ◽  
The One

Corrosion in ship structures is influenced by a variety of factors that are varying in time and space. Existing corrosion models used in practice only partially address the spatial variability of the corrosion process. Typical estimations of corrosion parameters are based on averaging measurements over structural elements from different ships and operational conditions, without considering the variability among and within the elements. However, this variability is important when determining the necessary inspection coverage, and it may influence the reliability of the ship structure. We develop a probabilistic spatio-temporal corrosion model based on a hierarchical approach, which represents the spatial variability of the corrosion process. The model includes the hierarchical levels vessel – compartment – frame – structural element – plate element. At all levels, variables representing common influencing factors are introduced. Moreover, at the lowest level, which is the one of the plate element, the corrosion process is modeled as a spatial random field. For illustrative purposes, the model is trained through Bayesian analysis with measurement data from a group of tankers. In this application it is found that there is significant spatial dependence among corrosion processes in different parts of the ships, which the proposed hierarchical model can capture. Finally, it is demonstrated how this spatial dependence can be exploited when making inference on the future condition of the ships.

Spatial Probabilistic Modeling of Corrosion in Ship Structures

2017 ◽  
Vol 3 (3) ◽  
Author(s):  
Jesus Luque ◽  
Rainer Hamann ◽  
Daniel Straub
Keyword(s):  
Spatial Variability ◽  
Spatial Dependence ◽  
Measurement Data ◽  
Corrosion Process ◽  
Model Parameters ◽  
Plate Element ◽  
Structural Element ◽  
Ship Structures ◽  
Operational Conditions ◽  
Corrosion Model

Corrosion in ship structures is influenced by a variety of factors that are varying in time and space. Existing corrosion models used in practice only partially address the spatial variability of the corrosion process. Typical estimations of corrosion model parameters are based on averaging measurements for one ship type over structural elements from different ships and operational conditions. Most models do not explicitly predict the variability and correlation of the corrosion process among multiple locations in the structure. This correlation is of relevance when determining the necessary inspection coverage, and it can influence the reliability of the ship structure. In this paper, we develop a probabilistic spatiotemporal corrosion model based on a hierarchical approach, which represents the spatial variability and correlation of the corrosion process. The model includes as hierarchical levels vessel–compartment–frame–structural element–plate element. At all levels, variables representing common influencing factors (e.g., coating life) are introduced. Moreover, at the lowest level, which is the one of the plate element, the corrosion process can be modeled as a spatial random field. For illustrative purposes, the model is trained through Bayesian analysis with measurement data from a group of tankers. In this application, the spatial dependence among corrosion processes in different parts of the ships is identified and quantified using the proposed hierarchical model. Finally, how this spatial dependence can be exploited when making inference on the future condition of the ships is demonstrated.

Numerical investigation on a melt-blowing die with internal stabilizers

2019 ◽  
pp. 152808371986693 ◽  
Author(s):  
Changchun Ji ◽  
Yudong Wang ◽  
Yafeng Sun
Keyword(s):  
Average Velocity ◽  
Fiber Diameter ◽  
Measurement Data ◽  
Melt Blowing ◽  
One Dimensional ◽  
Temperature Decay ◽  
Slot Die ◽  
The Common ◽  
The One ◽  
Peak Value

In order to decrease the fiber diameter and reduce the energy consumption in the melt-blowing process, a new slot die with internal stabilizers was designed. Using computational fluid dynamics technology, the new slot die was investigated. In the numerical simulation, the calculation data were validated with the laboratory measurement data. This work shows that the new slot die could increase the average velocity on the centerline of the air-flow field by 6.9%, compared with the common slot die. Simultaneously, the new slot die could decrease the back-flow velocity and the rate of temperature decay in the region close to the die head. The new slot die could reduce the peak value of the turbulent kinetic energy and make the fiber movements more gradual. With the one-dimensional drawing model, it proves that the new slot die has more edge on the decrease of fiber diameter than the common slot die.

scholarly journals Spatial variability and mapping of soil fertility status in a high-potential smallholder farming area under sub-humid conditions in Zimbabwe

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Gabriel Soropa ◽  
Olton M. Mbisva ◽  
Justice Nyamangara ◽  
Ermson Z. Nyakatawa ◽  
Newton Nyapwere ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Soil Properties ◽  
Soil Ph ◽  
Strong Evidence ◽  
Spatial Dependence ◽  
Random Component ◽  
Smallholder Farming ◽  
Mineral N ◽  
Spatial Trend ◽  
Spatial Trends

AbstractA study was conducted to examine spatial variability of soil properties related to fertility in maize fields across varying soil types in ward 10 of Hurungwe district, Zimbabwe; a smallholder farming area with sub-humid conditions and high yield potential. Purposively collected and geo-referenced soil samples were analyzed for texture, pH, soil organic carbon (OC), mineral N, bicarbonate P, and exchangeable K. Linear mixed model was used to analyze spatial variation of the data. The model allowed prediction of soil properties at unsampled sites by the empirical best linear unbiased predictor (EBLUP). Evidence for spatial dependence in the random component of the model was evaluated by calculating Akaike’s information criterion. Soil pH ranged from 4.0 to 6.9 and showed a strong spatial trend increasing from north to south, strong evidence for a difference between the home and outfields with homefields significantly higher and between soil textural classes with the sand clay loam fraction generally higher. Soil OC ranged from 0.2 to 2.02% and showed no spatial trend, but there was strong evidence for a difference between home and outfields, with mean soil OC in homefields significantly larger, and between soil textural classes, with soil OC largest in the sandy clay loams. Both soil pH and OC showed evidence for spatial dependence in the random effect, providing a basis for spatial prediction by the EBLUP, which was presented as a map. There were significant spatial trends in mineral N, available P and exchangeable K, all increasing from north to south; significant differences between homefields and outfields (larger concentrations in homefields), and differences between the soil textural classes with larger concentrations in the sandy clay loams. However, there was no evidence for spatial dependence in the random component, so no attempt was made to map these variables. These results show how management (home fields vs outfields), basic soil properties (texture) and other factors emerging as spatial trends influence key soil properties that determine soil fertility in these conditions. This implies that the best management practices may vary spatially, and that site-specific management is a desirable goal in conditions such as those which apply in Ward 10 of Hurungwe district in Zimbabwe.

Effect of Savanna windrow wood burning on the spatial variability of soil properties

2021 ◽  
Vol 51 ◽  
Author(s):  
Diogo Neia Eberhardt ◽  
Robélio Leandro Marchão ◽  
Pedro Rodolfo Siqueira Vendrame ◽  
Marc Corbeels ◽  
Osvaldo Guedes Filho ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Spatial Variability ◽  
Spatial Dependence ◽  
Chemical Properties ◽  
Spatial Arrangement ◽  
Nugget Effect ◽  
Tropical Savannas ◽  
Geostatistical Methods ◽  
Exchangeable Ca ◽  
Spherical Models

ABSTRACT Tropical Savannas cover an area of approximately 1.9 billion hectares around the word and are subject to regular fires every 1 to 4 years. This study aimed to evaluate the influence of burning windrow wood from Cerrado (Brazilian Savanna) deforestation on the spatial variability of soil chemical properties, in the field. The data were analysed by using geostatistical methods. The semivariograms for pH(H2O), pH(CaCl2), Ca, Mg and K were calculated according to spherical models, whereas the phosphorus showed a nugget effect. The cross semi-variograms showed correlations between pH(H2O) and pH(CaCl2) with other variables with spatial dependence (exchangeable Ca and Mg and available K). The spatial variability maps for the pH(H2O), pH(CaCl2), Ca, Mg and K concentrations also showed similar patterns of spatial variability, indicating that burning the vegetation after deforestation caused a well-defined spatial arrangement. Even after 20 years of use with agriculture, the spatial distribution of pH(H2O), pH(CaCl2), Ca, Mg and available K was affected by the wood windrow burning that took place during the initial deforestation.

scholarly journals GEOSTATISTICAL MODELING OF TIMBER VOLUME SPATIAL VARIABILITY FOR Tectona grandis L. F. PRECISION FORESTRY

CERNE ◽  
2017 ◽  
Vol 23 (1) ◽  
pp. 115-122 ◽  
Author(s):  
Allan Libanio Pelissari ◽  
Marcelo Roveda ◽  
Sidney Fernando Caldeira ◽  
Carlos Roberto Sanquetta ◽  
Ana Paula Dalla Corte ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Spatial Dependence ◽  
Tectona Grandis ◽  
Wood Products ◽  
Geostatistical Modeling ◽  
Timber Volume ◽  
Silvicultural Treatments ◽  
Punctual Kriging ◽  
Precision Forestry ◽  
Taper Models

ABSTRACT Considering the hypothesis that the wood volumes present spatial dependence, whose knowledge contributes for the precision forestry, the aim of this work was to estimate the volume spatial variability for timber assortments and identify their spatial patterns on Tectona grandis stands. A dataset of 1,038 trees was used to fit taper models and estimate the total stem, sawlog, and firewood volumes in 273 plots allocated on T. grandis stands at eight years old, which represents the second thinning that enables commercial volumes. Semivariograms models was applied to fit the spatial dependence, and punctual kriging was used to compose volume maps. Geostatistical modeling allowed us to estimate the T. grandis spatial variability and develop timber volume maps. Thus, silvicultural treatments, such as thinning and pruning, as well as for planning spatial interventions, are possible to be recommended for aimed wood products.

scholarly journals Design of a scanning laser meter for monitoring the spatio-temporal evolution of snow depth and its application in the Alps and in Antarctica

2016 ◽  
Vol 10 (4) ◽  
pp. 1495-1511 ◽  
Author(s):  
Ghislain Picard ◽  
Laurent Arnaud ◽  
Jean-Michel Panel ◽  
Samuel Morin
Keyword(s):  
Spatial Variability ◽  
Snow Depth ◽  
Laser Scanning ◽  
Single Point ◽  
Measurement Techniques ◽  
Strong Wind ◽  
Slow Increase ◽  
Automatic Instrument ◽  
Spatio Temporal ◽  
Wind Events

Abstract. Although both the temporal and spatial variations of the snow depth are usually of interest for numerous applications, available measurement techniques are either space-oriented (e.g. terrestrial laser scans) or time-oriented (e.g. ultrasonic ranging probe). Because of snow heterogeneity, measuring depth in a single point is insufficient to provide accurate and representative estimates. We present a cost-effective automatic instrument to acquire spatio-temporal variations of snow depth. The device comprises a laser meter mounted on a 2-axis stage and can scan  ≈  200 000 points over an area of 100–200 m2 in 4 h. Two instruments, installed in Antarctica (Dome C) and the French Alps (Col de Porte), have been operating continuously and unattended over 2015 with a success rate of 65 and 90 % respectively. The precision of single point measurements and long-term stability were evaluated to be about 1 cm and the accuracy to be 5 cm or better. The spatial variability in the scanned area reached 7–10 cm (root mean square) at both sites, which means that the number of measurements is sufficient to average out the spatial variability and yield precise mean snow depth. With such high precision, it was possible for the first time at Dome C to (1) observe a 3-month period of regular and slow increase of snow depth without apparent link to snowfalls and (2) highlight that most of the annual accumulation stems from a single event although several snowfall and strong wind events were predicted by the ERA-Interim reanalysis. Finally the paper discusses the benefit of laser scanning compared to multiplying single-point sensors in the context of monitoring snow depth.

scholarly journals ORGANIZATIONAL AND FUNCTIONAL FEATURES OF REGIONAL ELECTION CAMPAIGNS IN RUSSIA

2021 ◽  
Vol 5 (2) ◽  
pp. 179-185
Author(s):  
E.V. x E.V. Efanova
Keyword(s):  
Political Process ◽  
Election Campaigns ◽  
Electoral Process ◽  
Structural Element ◽  
Typical Structure ◽  
Political Actors ◽  
Electoral Campaigns ◽  
Election Process ◽  
Functional Features ◽  
The One

The article presents a structural and functional analysis of election campaigns in Russia. It is obvious that electoral campaigns of candidates are unfolding during the election period, which, through interaction with citizens, enlist their support and sympathy, which contributes to their achievement of the main goal - victory in the elections and, therefore, the seizure and retention of power. The election campaign, being a structural element of the electoral process, is a set of events carried out by various subjects of this process in order to win the election by attracting the votes of the electorate. In general, the electoral company, on the one hand, is a set of measures for organizing elections, regulated by law and carried out by election commissions, and, on the other, a set of actions of political actors involved in the electoral process. It was established that election campaigns have a typical structure, organizational features, political, administrative and socio-cultural characteristics at the federal and regional levels of the electoral process. Among the regional organizational and functional features of domestic election campaigns are: a high degree of intensity of the election process, the dependence of the success of regional election campaigns on the electoral activity of citizens, the orientation of candidates to the needs of the residents of the region, and a prompt response to criticism from the electoral community. The study of the features of the implementation of regional election campaigns is important for Russian reality, especially in the conditions of the ongoing formation and intensive development of the democratic political process in the Russian Federation at the present stage.

scholarly journals Spatio-Temporal Characteristics and Variation Pattern of the Atmospheric Particulate Matter Concentration: A Case Study of the Beijing–Tianjin–Hebei Region, China

Atmosphere ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 120
Author(s):  
Haoran Zhai ◽  
Jiaqi Yao ◽  
Guanghui Wang ◽  
Xinming Tang
Keyword(s):  
Particulate Matter ◽  
Measurement Data ◽  
Atmospheric Particulate Matter ◽  
Temporal Characteristics ◽  
Double Peaks ◽  
Spatio Temporal ◽  
Pm2.5 And Pm10 ◽  
Air Quality Monitoring Stations ◽  
Matter Concentration

Based on measurement data from air quality monitoring stations, the spatio-temporal characteristics of the concentrations of particles with aerodynamic equivalent diameters smaller than 2.5 and 10 μm (PM2.5 and PM10, respectively) in the Beijing–Tianjin–Hebei (BTH) region from 2015 to 2018 were analysed at yearly, seasonal, monthly, daily and hourly scales. The results indicated that (1) from 2015 to 2018, the annual average values of PM2.5 and PM10 concentrations and the PM2.5/PM10 ratio in the study area decreased each year; (2) the particulate matter (PM) concentration in winter was significantly higher than that in summer, and the PM2.5/PM10 ratio was highest in winter and lowest in spring; (3) the PM2.5 and PM10 concentrations exhibited a pattern of double peaks and valleys throughout the day, reaching peak values at night and in the morning and valleys in the morning and afternoon; and (4) with the use of an improved sine function to simulate the change trend of the monthly mean PM concentration, the fitting R2 values for PM2.5 and PM10 in the whole study area were 0.74 and 0.58, respectively. Moreover, the high-value duration was shorter, the low-value duration was longer, and the concentration decrease rate was slower than the increase rate.

scholarly journals Spatial variability of soil chemical properties after coffee tree removal

2009 ◽  
Vol 33 (5) ◽  
pp. 1507-1514 ◽  
Author(s):  
Sidney Rosa Vieira ◽  
Osvaldo Guedes Filho ◽  
Márcio Koiti Chiba ◽  
Heitor Cantarella
Keyword(s):  
Spatial Variability ◽  
Spatial Dependence ◽  
Crop Yields ◽  
Management Strategies ◽  
Chemical Properties ◽  
Spherical Model ◽  
Soil Chemical Properties ◽  
Kriging Interpolation ◽  
Geostatistical Methods ◽  
Plant Removal

Assessing the spatial variability of soil chemical properties has become an important aspect of soil management strategies with a view to higher crop yields with minimal environmental degradation. This study was carried out at the Centro Experimental of the Instituto Agronomico, in Campinas, São Paulo, Brazil. The aim was to characterize the spatial variability of chemical properties of a Rhodic Hapludox on a recently bulldozer-cleaned area after over 30 years of coffee cultivation. Soil samples were collected in a 20 x 20 m grid with 36 sampling points across a 1 ha area in the layers 0.0-0.2 and 0.2-0.4 m to measure the following chemical properties: pH, organic matter, K+, P, Ca2+, Mg2+, potential acidity, NH4-N, and NO3-N. Descriptive statistics were applied to assess the central tendency and dispersion moments. Geostatistical methods were applied to evaluate and to model the spatial variability of variables by calculating semivariograms and kriging interpolation. Spatial dependence patterns defined by spherical model adjusted semivariograms were made for all cited soil properties. Moderate to strong degrees of spatial dependence were found between 31 and 60 m. It was still possible to map soil spatial variability properties in the layers 0-20 cm and 20-40 cm after plant removal with bulldozers.

scholarly journals Age of the Post-rift Sequence I from the Araripe Basin, Lower Cretaceous, NE Brazil: implications for spatio-temporal correlation

2021 ◽  
Vol 24 (1) ◽  
pp. 37-46
Author(s):  
João Carlos Coimbra ◽  
Tiago Menezes Freire
Keyword(s):  
Critical Review ◽  
Lower Cretaceous ◽  
Temporal Correlation ◽  
Isotopic Analysis ◽  
The Other ◽  
Stratigraphic Framework ◽  
Spatio Temporal ◽  
Radiometric Ages ◽  
The One ◽  
Do So

A robust biostratigraphic zonation based on microfossils supports the stratigraphic framework and correlation of the interior basins of the Lower Cretaceous of NE Brazil. This zonation has also allowed correlations with coeval sections in the Brazilian marginal basins and in the Gabon and Congo basins (central-west Africa). These records, consisting mainly of non-marine sediments, were a great challenge with regard to the correlation with the International Chronostratigraphic Chart. Therefore, local stages were used, the most recent being the Alagoas local Brazilian Stage, with which the Post-rift Sequence I of the Araripe Basin is related. Regarding lithostratigraphy, this sequence includes the Rio da Batateira (Barbalha for some authors) and Santana formations, the last one with the famous Crato, Ipubi, and Romualdo members, from the base to the top. Although currently there is a consensus on the age of the Alagoas local Brazilian Stage in the Araripe Basin, recently a new age for at least part of the Post-rift Sequence I was proposed. This new proposal, based on isotopic analysis of Re-Os, arose as a panacea to correlate the Rio da Batateira Formation and the Crato and Ipubi members with the international stages. Surprisingly, their authors, although on the one hand, they seem to underestimate biostratigraphic results, on the other they seek to support their proposal from microfossils studied by previous authors, but they do so in an inappropriate way, leading readers to misinterpret their results. Therefore, this paper presents a critical review on the age of the Alagoas local Brazilian Stage in the Araripe Basin and nearby basins, refuting a Barremian age for part of the Post-rift Sequence I. Keywords: Alagoas local Brazilian Stage, biostratigraphy, ostracods, palynomorphs, radiometric ages.

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