Mechanics of Ice Rubble Over Multiple Scales

2015 ◽  
Author(s):  
E. Bailey ◽  
R. Taylor ◽  
K. R. Croasdale
Keyword(s):  
Sea Ice ◽  
Large Scale ◽  
Oil And Gas ◽  
Multiple Scales ◽  
Offshore Structures ◽  
Composition And Structure ◽  
Block Level ◽  
Design Loads ◽  
The One ◽  
Sintering Processes

The mechanics of ice rubble plays an important role in many different engineering applications, including ice-structure interactions with oil and gas infrastructure, river and lake engineering, and ship-ice interactions in northern shipping lanes. Of particular interest are the massive accumulations of rubble formed by shear or compression in the ice cover, which consolidate to form sea ice ridges that can be hazards to such structures. These are common ice features in Arctic and sub-Arctic environments and as a result often govern the design loads for ships, coastal and offshore structures operating in these environments. In addition, ridge keels can scour the seafloor in relatively shallow waters posing a threat to pipelines and other subsea facilities. It is not clear what load an ice rubble feature can exert on a given structure and how it will deform. It will depend on a number of parameters including the age of the feature, its composition and structure, and its strength and failure behaviour. This paper will examine the mechanical properties of ice rubble over multiple scales. The paper will begin at the one block level, describing how ice block properties vary over time, before advancing to look at the bonding/sintering processes that occur between two ice blocks and eventually the processes that take place between multiple ice blocks (i.e., ice rubble) and large scale sea ice ridges. Particular attention will be paid to the effects temperature and pressure have on ice rubble, as these parameters are believed to be important to our understanding of its behavior.

scholarly journals Analysis of Offshore Structures Based on Response Spectrum of Ice Force

2019 ◽  
Vol 7 (11) ◽  
pp. 417 ◽  
Author(s):  
Liu ◽  
Li ◽  
Zhang
Keyword(s):  
Sea Ice ◽  
Large Scale ◽  
Response Spectrum ◽  
Time History ◽  
Offshore Structures ◽  
Potential Threat ◽  
Influence Coefficients ◽  
Design Response Spectrum ◽  
Ice Force ◽  
Bending Failure

With the development of large-scale offshore projects, sea ice is a potential threat to the safety of offshore structures. The main forms of damage to bottom-fixed offshore structures under sea ice are crushing failure and bending failure. Referred to as the concept of seismic response spectrums, the design response spectrum of offshore structures induced by the crushing and bending ice failure is presented. Selecting the Bohai Sea in China as an example, the sea areas were divided into different ice zones due to the different sea ice parameters. Based on the crushing and bending failure power spectral densities of ice force, a large amount of ice force time-history samples are firstly generated for each ice zone. The time-history of the maximum responses of a series of single degree of freedom systems with different natural frequencies under the ice force are calculated and subsequently, a response spectrum curve is obtained. Finally, by fitting all the response spectrum curves from different samples, the design response spectrum is generated for each ice zone. The ice force influence coefficients for crushing and bending failure are obtained, which can be used to estimate the stochastic sea ice force acting on a structure conveniently in a static way. A comparison of the proposed response spectrum method with the Monte Carlo method by a numerical example shows good agreement.

Methodology to Evaluate Sea Ice Loads for Seasonal Operations

2015 ◽  
Author(s):  
Jan Thijssen ◽  
Mark Fuglem
Keyword(s):  
Sea Ice ◽  
Offshore Structures ◽  
Ice Thickness ◽  
Safety Level ◽  
Site Specific ◽  
Design Load ◽  
Ice Load ◽  
Ice Conditions ◽  
Design Loads ◽  
Ice Loads

Offshore structures designed for operation in regions where sea ice is present will include a sea ice load component in their environmental loading assessment. Typically ice loads of interest are for 10−2, 10−3 or 10−4 annual probability of exceedance (APE) levels, with appropriate factoring to the required safety level. The ISO 19906 standard recommends methods to determine global sea ice loads on vertical structures, where crushing is the predominant failure mode. Fitted coefficients are proposed for both Arctic and Sub-Arctic (e.g. Baltic) conditions. With the extreme ice thickness expected at the site of interest, an annual global sea ice load can be derived deterministically. Although the simplicity of the proposed relation provides quick design load estimates, it lacks accuracy because the only dependencies are structure width, ice thickness and provided coefficients; no consideration is given to site-specific sea ice conditions and the corresponding exposure. Additionally, no term is provided for including ice management in the design load basis. This paper presents a probabilistic methodology to modify the deterministic ISO 19906 relations for determining global and local first-year sea ice loads on vertical structures. The presented methodology is based on the same ice pressure data as presented in ISO 19906, but accounts better for the influence of ice exposure, ice management and site-specific sea ice data. This is especially beneficial for ice load analyses of seasonal operations where exposure to sea ice is limited, and only thinner ice is encountered. Sea ice chart data can provide site-specific model inputs such as ice thickness estimates and partial concentrations, from which corresponding global load exceedance curves are generated. Example scenarios show dependencies of design loads on season length, structural geometry and sea ice conditions. Example results are also provided, showing dependency of design loads on the number of operation days after freeze-up, providing useful information for extending the drilling season of MODUs after freeze-up occurs.

Efficiency of Ice Management for Arctic Offshore Operations

2014 ◽  
Author(s):  
Badr El Bakkay ◽  
Edmond Coche ◽  
Kaj Riska
Keyword(s):  
Sea Ice ◽  
Oil And Gas ◽  
Weather Conditions ◽  
Optimal Number ◽  
The Arctic ◽  
Floating Platform ◽  
Oil And Gas Fields ◽  
Exploration And Production ◽  
Arctic Exploration ◽  
The One

The exploration and production of polar oil and gas fields, which are technologically challenging due to extreme weather conditions, are also constrained by strong environmental issues. Safe and economical activities in such hostile and fragile regions require very insightful engineering. The presence of sea ice is representing a triple challenge: economical, technological and environmental. This makes the Arctic exploration and production activities complex. Ice Management (IM) is one of the tools that could efficiently assist to develop Arctic reserves. However, for each project that uses IM operations, a preliminary study is required to evaluate the efficiency of these support operations and to estimate the possible extension in the season of operation of a field. Efficiency of an IM philosophy can be estimated in a global view based on the extension in the operability window. In a more detailed view, it can be assessed taking into account the optimal number of icebreakers, the IM patterns, the available time for eventual disconnection, and the floe size reduction (leading to ice load reduction). For this study, we will focus on the ice floe size and loads reduction. The most common approach for physical management of sea ice is the one where icebreakers reduce floe size of the drifting ice upstream the floating platform (ref. Moran et al. [1], Coche et al. [2]). This paper describes this philosophy and demonstrates based on real-time simulation that its benefit is limited to mild ice scenarios such as unidirectional ice drift. A more efficient way to manage sea ice is (1) to identify the most hazardous events (e.g. big ridges); (2) prioritize these events; and (3) deal with them starting by the most hazardous one.

Some comparisons between heterogeneous and homogeneous layers for nonlinear SH waves in terms of heterogeneous and nonlinear effects

2020 ◽  
pp. 108128652094635 ◽  
Author(s):  
Dilek Demirkuş
Keyword(s):  
Solitary Wave ◽  
Large Scale ◽  
Multiple Scales ◽  
Nonlinear Effects ◽  
Small Scale ◽  
Solitary Wave Solutions ◽  
Nls Equation ◽  
Sh Waves ◽  
Wave Solutions ◽  
The One

This paper aims to make some comparative studies between heterogeneous and homogeneous layers for nonlinear shear horizontal (SH) waves in terms of the heterogeneous and nonlinear effects. Therefore, with this aim, two layers are defined as follows: on the one hand, one layer consists of hyperelastic, isotropic, heterogeneous, and generalized neo-Hookean materials; on the other hand, another layer is made up of hyperelastic, isotropic, homogeneous, and generalized neo-Hookean materials. Moreover, it is assumed that upper boundaries are stress-free and lower boundaries are rigidly fixed. The method of multiple scales is used in both analyses, in addition to using the known solutions of the nonlinear Schrödinger (NLS) equation, called bright and dark solitary wave solutions; these comparisons are made, numerically, and then all results are given for the lowest branch of both dispersion relations, graphically. Moreover, these comparisons are observed both on a large scale and on a small scale, not only in terms of the bright and dark solitary wave solutions but also in terms of the heterogeneous and nonlinear effects.

scholarly journals On wind-driven energetics of subtropical gyres

2020 ◽  
Author(s):  
William K. Dewar ◽  
Quentin Jamet ◽  
Bruno Deremble ◽  
Nicolas Wienders
Keyword(s):  
General Circulation ◽  
Large Scale ◽  
Multiple Scales ◽  
Numerical Study ◽  
Mean Field ◽  
Western Boundary ◽  
The North ◽  
The Mean ◽  
The One ◽  
Mean Circulation

<p>The flow of energy in the wind-driven circulation is examined in a <br>combined theoretical and numerical study. Based on a multiple scales <br>analysis of the ocean interior, we find the mesoscale field is strongly <br>affected by the ventilated thermocline, but no feed back from the eddies <br>to the large scale is found.  We then analyze the western boundary <br>region arguing that the associated currents divide between coastal jets, <br>which conserve mean energy, and open ocean, separated jet extensions<br>where the mesoscale is energized by the mean field.   It is the <br>separated jet zone where the primary loss of general circulation energy <br>to the mesoscale occurs.  Connections to the `Thickness Weighted <br>Average' form of the primitive equations are made which support the <br>differing roles of the eddies in these regions.  These ideas are then <br>tested by an analysis of a regional primitive equation 1/12-degree <br>numerical model of the North Atlantic. The predictions of the theory are <br>generally supported by the numerical results.  The one exception is that <br>topographic irregularities in the coastal jet spawn eddies, although <br>they contribute modestly to the energy budget.  We therefore conclude <br>the primary sink of wind input into the mean circulation is in the <br>separated jet, and not the interior.  The analysis also shows<br>wind forcing is much smaller than the interior energy fluxes. Thus, the <br>general circulation is characterized as recirculating energy in the <br>manner of a Fofonoff gyre.</p>

Optimal Test Assembly in Practice

2013 ◽  
Vol 221 (3) ◽  
pp. 190-200 ◽  
Author(s):  
Jörg-Tobias Kuhn ◽  
Thomas Kiefer
Keyword(s):  
Particle Physics ◽  
Large Scale ◽  
Block Design ◽  
Linear Optimization ◽  
Mixed Integer ◽  
Optimal Test ◽  
Automated Test Assembly ◽  
Test Assembly ◽  
Block Level ◽  
Mixed Integer Linear Optimization

Several techniques have been developed in recent years to generate optimal large-scale assessments (LSAs) of student achievement. These techniques often represent a blend of procedures from such diverse fields as experimental design, combinatorial optimization, particle physics, or neural networks. However, despite the theoretical advances in the field, there still exists a surprising scarcity of well-documented test designs in which all factors that have guided design decisions are explicitly and clearly communicated. This paper therefore has two goals. First, a brief summary of relevant key terms, as well as experimental designs and automated test assembly routines in LSA, is given. Second, conceptual and methodological steps in designing the assessment of the Austrian educational standards in mathematics are described in detail. The test design was generated using a two-step procedure, starting at the item block level and continuing at the item level. Initially, a partially balanced incomplete item block design was generated using simulated annealing, whereas in a second step, items were assigned to the item blocks using mixed-integer linear optimization in combination with a shadow-test approach.

Global Economic Crisis of 2008-2009: Sources and Roots

2009 ◽  
pp. 18-31
Author(s):  
G. Rapoport ◽  
A. Guerts
Keyword(s):  
Oil And Gas ◽  
Trade Deficit ◽  
Developed Countries ◽  
The Other ◽  
Energy Resources ◽  
Market Mechanisms ◽  
Production Output ◽  
The One ◽  
To Receive ◽  
Partial Destruction

In the article the global crisis of 2008-2009 is considered as superposition of a few regional crises that occurred simultaneously but for different reasons. However, they have something in common: developed countries tend to maintain a strong level of social security without increasing the real production output. On the one hand, this policy has resulted in trade deficit and partial destruction of market mechanisms. On the other hand, it has clashed with the desire of several oil and gas exporting countries to receive an exclusive price for their energy resources.

A method of technical diagnostics for offshore structures

1994 ◽  
Vol 16 (2) ◽  
pp. 43-48
Author(s):  
Do Son
Keyword(s):  
Diagnostic Method ◽  
Joint Venture ◽  
Oil And Gas ◽  
Residual Life ◽  
Life Time ◽  
Offshore Structures ◽  
Technical Diagnostics ◽  
Offshore Platforms ◽  
South Vietnam ◽  
Local Destruction

This paper describes the results of measurements and analysis of the parameters, characterizing technical state of offshore platforms in Vietnam Sea. Based on decreasing in time material characteristics because of corrosion and local destruction assessment on residual life time of platforms is given and variants for its repair are recommended. The results allowed to confirm advantage of proposed technical diagnostic method in comparison with others and have been used for oil and gas platform of Joint Venture "Vietsovpetro" in South Vietnam.

Financial and Economic Support of Innovation Processes in the Russian Fuel and Energy Complex

2019 ◽  
Vol 12 (3) ◽  
pp. 77-85
Author(s):  
L. D. Kapranova ◽  
T. V. Pogodina
Keyword(s):  
Oil Recovery ◽  
Large Scale ◽  
Oil And Gas ◽  
New Technologies ◽  
Innovative Development ◽  
Oil Reserves ◽  
Energy Complex ◽  
Innovation Activities ◽  
Substantial Investment ◽  
The Government

The subject of the research is the current state of the fuel and energy complex (FEC) that ensures generation of a significant part of the budget and the innovative development of the economy.The purpose of the research was to establish priority directions for the development of the FEC sectors based on a comprehensive analysis of their innovative and investment activities. The dynamics of investment in the fuel and energy sector are considered. It is noted that large-scale modernization of the fuel and energy complex requires substantial investment and support from the government. The results of the government programs of corporate innovative development are analyzed. The results of the research identified innovative development priorities in the power, oil, gas and coal sectors of the fuel and energy complex. The most promising areas of innovative development in the oil and gas sector are the technologies of enhanced oil recovery; the development of hard-to-recover oil reserves; the production of liquefied natural gas and its transportation. In the power sector, the prospective areas are activities aimed at improving the performance reliability of the national energy systems and the introduction of digital technologies. Based on the research findings, it is concluded that the innovation activities in the fuel and energy complex primarily include the development of new technologies, modernization of the FEC technical base; adoption of state-of-the-art methods of coal mining and oil recovery; creating favorable economic conditions for industrial extraction of hard-to-recover reserves; transition to carbon-free fuel sources and energy carriers that can reduce energy consumption and cost as well as reducing the negative FEC impact on the environment.

First grammar books in the Habsburg Monarchy: individual initiative and regulatory interference by the state (1760s–1770s)

2020 ◽  
Vol 2019 (2 (11)) ◽  
pp. 137-157
Author(s):  
Olga V. Khavanova ◽  
Keyword(s):  
Eighteenth Century ◽  
State Policy ◽  
Large Scale ◽  
Language Use ◽  
Linguistic Diversity ◽  
Mother Tongue ◽  
German Language ◽  
Habsburg Monarchy ◽  
Private Initiative ◽  
The One

The second half of the eighteenth century in the lands under the sceptre of the House of Austria was a period of development of a language policy addressing the ethno-linguistic diversity of the monarchy’s subjects. On the one hand, the sphere of use of the German language was becoming wider, embracing more and more segments of administration, education, and culture. On the other hand, the authorities were perfectly aware of the fact that communication in the languages and vernaculars of the nationalities living in the Austrian Monarchy was one of the principal instruments of spreading decrees and announcements from the central and local authorities to the less-educated strata of the population. Consequently, a large-scale reform of primary education was launched, aimed at making the whole population literate, regardless of social status, nationality (mother tongue), or confession. In parallel with the centrally coordinated state policy of education and language-use, subjects-both language experts and amateur polyglots-joined the process of writing grammar books, which were intended to ease communication between the different nationalities of the Habsburg lands. This article considers some examples of such editions with primary attention given to the correlation between private initiative and governmental policies, mechanisms of verifying the textbooks to be published, their content, and their potential readers. This paper demonstrates that for grammar-book authors, it was very important to be integrated into the patronage networks at the court and in administrative bodies and stresses that the Vienna court controlled the process of selection and financing of grammar books to be published depending on their quality and ability to satisfy the aims and goals of state policy.

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