Optimal Design of Submarine Pipelines by a Genetic Algorithm with Embedded On-Bottom Stability Criteria

This work describes a computational tool, based on an evolutionary algorithm, for the synthesis and optimization of submarine pipeline routes considering the incorporation of on-bottom stability criteria (OBS). This comprises a breakthrough in the traditional pipeline design methodology, where the definition of a route and the stability calculations had been performed independently: firstly, the route is defined according to geographical-topographical issues (including manual/visual inspection of seabed bathymetry and obstacles); afterwards, stability is verified, and mitigating procedures (such as ballast weight) are specified. This might require several design spirals until a final configuration is reached, or (most commonly) has led to excessive costs for the mitigation of instability problems. The optimization tool evaluates each candidate route by incorporating, as soft and hard constraints, several criteria usually considered in the manual design (pipeline length, bathymetry data, obstacles); also, with the incorporation of OBS criteria into the objective function, stability becomes an integral part of the optimization process, simultaneously handling minimization of length and cost of mitigating procedures. Case studies representative of actual applications are presented. The results show that OBS criteria significantly influences the best route, indicating that the tool can reduce the design time of a pipeline and minimize installation/operational costs.

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A unique application and point of truth for Naval Architecture Calculations

10.5957/wmtc-2015-108 ◽

2015 ◽

Author(s):

Rodrigo Perez ◽

Verónica Alonso

Keyword(s):

Concept Design ◽

Stability Criteria ◽

Power Prediction ◽

Naval Architecture ◽

Complete Control ◽

Intact Stability ◽

Damage Stability ◽

Cad Cam ◽

The Stability ◽

Definition Of

Many tools handle with the calculation of compartment definition, hydrostatics, intact and damage stability and power prediction, but these calculations are separated from the rest of ship CAD/CAM tools. Ship designers need to work closely with the shipyards, in a complex and distributed environment making necessary to have suitable tools at early design stages to ensure profitable projects. Naval architecture is handled in FORAN with a revolutionary approach, where integration and advanced features are the relevant characteristics in a single and complete set of applications that are used in conjunction to other disciplines, from concept design to operation. This new approach groups the former modules for naval architecture available in FORAN from many years, is intuitive and user-friendly. The information is stored in a database instead of a wide set of files. As regards this feature, there are two different alternatives depending on the scope of the project. If the ship designer wants to calculate only naval architecture calculations, the solutions is based on a SQLITE database suitable for a standalone application. This approach benefits a ship design office, in the study of different design alternatives very quickly but having a complete control of them. The other option is integrating the Naval Architecture with the rest of FORAN design disciplines, in a single database based in Oracle. In this case, the great benefit comes from the single truth of data from concept design to operation, which ensures dramatically the reduction of errors and re-work. After the definition of compartments in 3D, by using a very fast application, the module guides the user through the naval architecture calculations with a tree of elements very intuitive, with powerful key algorithms and with a solid representation of spaces. The definition of the necessary entities to make any kind of calculation is very fast. For the intact stability a set of standard stability criteria is provided. It is based in a quick definition of loading conditions, initial situations, flooding conditions and compartment subdivisions. And for the evaluation of the damage stability a set of standard stability criteria are also provided, following deterministic and probabilistic approaches. With these tools any naval architect is able to make very fast all the necessary studies to assure the stability regulations are complied with.

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Synthesis and Optimization of Submarine Pipeline Routes Considering VIV-Induced Fatigue on Free Spans

Volume 7: CFD and VIV ◽

10.1115/omae2013-11345 ◽

2013 ◽

Cited By ~ 1

Author(s):

Juliana Souza Baioco ◽

Juan Pablo Inza Blanco ◽

Bruno Martins Jacovazzo ◽

Carl Horst Albrecht ◽

Beatriz Souza Leite Pires de Lima ◽

...

Keyword(s):

Evolutionary Algorithms ◽

Objective Function ◽

Case Studies ◽

Fitness Function ◽

Structural Behavior ◽

Submarine Pipeline ◽

Computational Tool ◽

Screening Criteria ◽

Vortex Induced Vibrations ◽

Seabed Bathymetry

Researchers from Petrobras and LAMCSO/COPPE have been involved in the development and implementation of a computational tool, based on Evolutionary Algorithms, for the synthesis and optimization of submarine pipeline routes. In this tool, randomly generated candidate routes are evaluated in terms of several criteria, incorporated in an objective (or fitness) function to take into account the relevant aspects that should be considered in the design of a route. Previous works described the initial steps taken towards the development of such tool, including the geometrical representation of a route, and some of the terms of the objective function associated with a preliminary, global step of the optimization process (such as total pipeline length, and geographical-topographical issues associated with the route geometry and to the seabed bathymetry and obstacles). Special attention was dedicated to the implementation of On-Bottom Stability (OBS) criteria such as the proposed in the DNV-RP-F109 code. This work is focused on another aspect related to the structural behavior of the pipe under hydrostatic and environmental loadings; more specifically, fatigue induced by vortex induced vibrations (VIV) on free spans along the candidate routes. Special attention is dedicated to the implementation of the screening criteria proposed in the DNV-RP-F105 code. Case studies are presented to assess the influence of the VIV criteria on the results of the optimization tool.

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Completeness on the stability criterion of fractional order LTI systems

Fractional Calculus and Applied Analysis ◽

10.1515/fca-2017-0008 ◽

2017 ◽

Vol 20 (1) ◽

Cited By ~ 25

Author(s):

Yiheng Wei ◽

Yuquan Chen ◽

Songsong Cheng ◽

Yong Wang

Keyword(s):

Fractional Order ◽

Stability Criterion ◽

Positive Definite Matrix ◽

Order System ◽

Linear Matrix ◽

Matrix Inequalities ◽

Stability Criteria ◽

The Stability ◽

Definition Of ◽

And Control

AbstractThe importance of the concept of stability in fractional order system and control has been recognized for some time now. Recently, it has become evident that many conclusions were drawn, but little consensus was reached. Consequently, there is an urgent need for a much deeper understanding of such a concept. With the definition of fractional order positive definite matrix, a set of equivalent and elegant stability criteria are developed via revisiting a stability criterion we proposed before. All the results are formed in terms of linear matrix inequalities. Afterwards, a series of interesting properties of these criteria are revealed profoundly, including completeness, singularity, conservatism, etc. Eventually, a simulation study is provided to validate the effectiveness of the obtained results.

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Synthesis and Optimization of Submarine Pipeline Routes Considering On-Bottom Stability Criteria

Volume 4: Pipeline and Riser Technology ◽

10.1115/omae2011-49373 ◽

2011 ◽

Cited By ~ 2

Author(s):

Mauro Henrique Alves de Lima ◽

Juliana Souza Baioco ◽

Carl Horst Albrecht ◽

Beatriz Souza Leite Pires de Lima ◽

Breno Pinheiro Jacob ◽

...

Keyword(s):

Evolutionary Algorithms ◽

Objective Function ◽

Case Studies ◽

Fitness Function ◽

Optimization Process ◽

Structural Behavior ◽

Stability Criteria ◽

Submarine Pipeline ◽

Computational Tool ◽

Geometrical Representation

Researchers from Petrobras and LAMCSO/COPPE/UFRJ are currently involved in the development and implementation of a computational tool, based in Evolutionary Algorithms, for the synthesis and optimization of submarine pipeline routes. In this tool, randomly generated candidate routes are evaluated in terms of several criteria, incorporated in an objective (or fitness) function to take into account the relevant aspects that should be considered in the design of a route. A previous work [1] described the initial steps taken towards the development of such tool. In that work, attention was dedicated to the geometrical representation of a route, and to some of the terms of the objective function associated with a preliminary, global step of the optimization process (such as total pipeline length, and geographical-topographical issues associated with the route geometry and to the seabottom bathymetry and obstacles). Now, this work focuses in other aspects related to the structural behavior of the pipe, under hydrostatic and environmental loadings; more specifically, special attention is dedicated to the implementation of On-Bottom Stability (OBS) criteria such as the proposed in the RP-F109 code [2]. Case studies are presented to illustrate the use of the optimization tool and to assess the influence of the OBS criteria.

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Postmodern More

Moreana ◽

10.3366/more.2003.40.1-2.14 ◽

2003 ◽

Vol 40 (Number 153- (1-2) ◽

pp. 219-239

Author(s):

Anne Lake Prescott

Keyword(s):

Human Language ◽

Thomas More ◽

The Stability ◽

Definition Of ◽

Recent Critic

Thomas More is often called a “humanist,” and rightly so if the word has its usual meaning in scholarship on the Renaissance. “Humanist” has by now acquired so many different and contradictory meanings, however, that it needs to be applied carefully to the likes of More. Many postmodernists tend to use the word, pejoratively, to mean someone who believes in an autonomous self, the stability of words, reason, and the possibility of determinable meanings. Without quite arguing that More was a postmodernist avant la lettre, this essay suggests that he was not a “humanist” who stalks the pages of much recent postmodernist theory and that in fact even while remaining a devout Catholic and sensible lawyer he was quite as aware as any recent critic of the slipperiness of human selves and human language. It is time that literary critics tightened up their definition of “humanist,” especially when writing about the Renaissance.

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Influence of study model, baseline catalytic concentrations and analytical system on the stability of serum alanine aminotransferase

Advances in Laboratory Medicine / Avances en Medicina de Laboratorio ◽

10.1515/almed-2020-0021 ◽

2020 ◽

Vol 1 (2) ◽

Author(s):

Josep Miquel Bauça ◽

Andrea Caballero ◽

Carolina Gómez ◽

Débora Martínez-Espartosa ◽

Isabel García del Pino ◽

...

Keyword(s):

Alanine Aminotransferase ◽

Experimental Models ◽

Individual Variability ◽

Serum Samples ◽

Multicentric Study ◽

Different Temperatures ◽

The Stability ◽

Analytical System ◽

Definition Of ◽

Analytical Platforms

AbstractObjectivesThe stability of the analytes most commonly used in routine clinical practice has been the subject of intensive research, with varying and even conflicting results. Such is the case of alanine aminotransferase (ALT). The purpose of this study was to determine the stability of serum ALT according to different variables.MethodsA multicentric study was conducted in eight laboratories using serum samples with known initial catalytic concentrations of ALT within four different ranges, namely: <50 U/L (<0.83 μkat/L), 50–200 U/L (0.83–3.33 μkat/L), 200–400 U/L (3.33–6.67 μkat/L) and >400 U/L (>6.67 μkat/L). Samples were stored for seven days at two different temperatures using four experimental models and four laboratory analytical platforms. The respective stability equations were calculated by linear regression. A multivariate model was used to assess the influence of different variables.ResultsCatalytic concentrations of ALT decreased gradually over time. Temperature (−4%/day at room temperature vs. −1%/day under refrigeration) and the analytical platform had a significant impact, with Architect (Abbott) showing the greatest instability. Initial catalytic concentrations of ALT only had a slight impact on stability, whereas the experimental model had no impact at all.ConclusionsThe constant decrease in serum ALT is reduced when refrigerated. Scarcely studied variables were found to have a significant impact on ALT stability. This observation, added to a considerable inter-individual variability, makes larger studies necessary for the definition of stability equations.

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Design Methodology of Laminating Tools

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.657.121 ◽

2014 ◽

Vol 657 ◽

pp. 121-125

Author(s):

Daniel Măgurian ◽

Gheorghe Oancea

Keyword(s):

Software Package ◽

Design Methodology ◽

Software Tool ◽

Design Time ◽

Standard Design ◽

Automotive Interior ◽

Main Frame

This paper presents a design methodology of laminating tools for automotive interior parts using CATIA software package. The authors developed a software tool namedLTFrameDesignusingVBA for Applicationunder CATIA package, which automatically generates the main frame of the laminating tool according to the parts shapes, its dimensions and designer requirements. The software automates some stages of standard design and minimizes the design time and costs. The paper also presents the design stages which are followed by the user to obtain a 3D complete assembly of the laminating tool.

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Reliable Learning with PDE-Based CNNs and DenseNets for Detecting COVID-19, Pneumonia, and Tuberculosis from Chest X-Ray Images

Mathematics ◽

10.3390/math9040434 ◽

2021 ◽

Vol 9 (4) ◽

pp. 434

Author(s):

Anca Nicoleta Marginean ◽

Delia Doris Muntean ◽

George Adrian Muntean ◽

Adelina Priscu ◽

Adrian Groza ◽

...

Keyword(s):

Transfer Learning ◽

Negative Impact ◽

X Ray ◽

Domain Specific ◽

Direct Training ◽

Public Data ◽

Normal Chest ◽

Chest X Ray ◽

The Stability ◽

Definition Of

It has recently been shown that the interpretation by partial differential equations (PDEs) of a class of convolutional neural networks (CNNs) supports definition of architectures such as parabolic and hyperbolic networks. These networks have provable properties regarding the stability against the perturbations of the input features. Aiming for robustness, we tackle the problem of detecting changes in chest X-ray images that may be suggestive of COVID-19 with parabolic and hyperbolic CNNs and with domain-specific transfer learning. To this end, we compile public data on patients diagnosed with COVID-19, pneumonia, and tuberculosis, along with normal chest X-ray images. The negative impact of the small number of COVID-19 images is reduced by applying transfer learning in several ways. For the parabolic and hyperbolic networks, we pretrain the networks on normal and pneumonia images and further use the obtained weights as the initializers for the networks to discriminate between COVID-19, pneumonia, tuberculosis, and normal aspects. For DenseNets, we apply transfer learning twice. First, the ImageNet pretrained weights are used to train on the CheXpert dataset, which includes 14 common radiological observations (e.g., lung opacity, cardiomegaly, fracture, support devices). Then, the weights are used to initialize the network which detects COVID-19 and the three other classes. The resulting networks are compared in terms of how well they adapt to the small number of COVID-19 images. According to our quantitative and qualitative analysis, the resulting networks are more reliable compared to those obtained by direct training on the targeted dataset.

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Dissipative instability of the MHD tangential discontinuity in magnetized plasmas with anisotropic viscosity and thermal conductivity

Journal of Plasma Physics ◽

10.1017/s0022377800019279 ◽

1996 ◽

Vol 56 (2) ◽

pp. 285-306 ◽

Cited By ~ 26

Author(s):

M. S. Ruderman ◽

E. Verwichte ◽

R. Erdélyi ◽

M. Goossens

Keyword(s):

Thermal Conductivity ◽

Dispersion Equation ◽

Viscosity Coefficient ◽

Tangential Discontinuity ◽

Stability Criteria ◽

Threshold Velocity ◽

Cold Plasmas ◽

The Difference ◽

The Stability ◽

Anisotropic Viscosity

The stability of the MHD tangential discontinuity is studied in compressible plasmas in the presence of anisotropic viscosity and thermal conductivity. The general dispersion equation is derived, and solutions to this dispersion equation and stability criteria are obtained for the limiting cases of incompressible and cold plasmas. In these two limiting cases the effect of thermal conductivity vanishes, and the solutions are only influenced by viscosity. The stability criteria for viscous plasmas are compared with those for ideal plasmas, where stability is determined by the Kelvin—Helmholtz velocity VKH as a threshold for the difference in the equilibrium velocities. Viscosity turns out to have a destabilizing influence when the viscosity coefficient takes different values at the two sides of the discontinuity. Viscosity lowers the threshold velocity V below the ideal Kelvin—Helmholtz velocity VKH, so that there is a range of velocities between V and VKH where the overstability is of a dissipative nature.

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The operational efficiency of passenger aircraft

Aircraft Engineering and Aerospace Technology ◽

10.1108/17488840610639663 ◽

2006 ◽

Vol 78 (1) ◽

pp. 32-38 ◽

Cited By ~ 5

Author(s):

Donald McLean

Keyword(s):

Design Methodology ◽

Operational Efficiency ◽

Civil Aviation ◽

Content Type ◽

Transport Economics ◽

Load Factors ◽

Consistent Assessment ◽

Definition Of ◽

Passenger Aircraft ◽

Practical Implications

PurposeTo provide for the use of airlines and other civil aviation organizations a practical definition of operational efficiency and to show how it can be determined.Design/methodology/approachA brief account of air transport economics is used to demonstrate how bom load factors and aircraft utilization need to be considered in assessing operational efficiency. Then other efficiencies are treated briefly before an example is given of how the better of two fictitious aircraft can be chosen for a particular route. A second example involving the calculation of the operational efficiency achieved by an imaginary airline is also given to show that the typical value is lower than might be expected, particularly in view of the relatively high load factors involved.FindingsProvides performance values and economic figures which are typical of current airline operations.Practical implicationsUse of the proposed definition will allow the consistent assessment of the economic performance of airlines.Originality/valueAt present there is no definition of operational efficiency in general use although it is greatly needed by airlines. The definition proposed in this paper is practical and easy to use.

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