Nonlinear Dynamics of a Spar Platform

2012 ◽  
Author(s):  
Elvidio Gavassoni ◽  
Paulo Batista Gonçalves ◽  
Deane M. Roehl
Keyword(s):  
Asymptotic Methods ◽  
Weather Conditions ◽  
Gas Production ◽  
Spar Platform ◽  
Highly Nonlinear ◽  
Oil And Natural Gas ◽  
The Stability ◽  
Floating Platforms ◽  
And Storage

Spar floating platforms have been largely used for deep water drilling, oil and natural gas production and storage of these fluids. In extreme weather conditions such structures may exhibit a highly nonlinear dynamic behavior. In this paper a 2-DOF model is used to study the heave and pitch coupled response in free and forced vibration. Special attention is given to the determination of the nonlinear vibration modes (NNMs). Non-similar and similar NNMs are obtained analytically by direct application of asymptotic methods and the results show important NNM features such as instability and multiplicity of modes. The NNMs are used to generate reduced order models that consist of 1-DOF nonlinear oscillators. It facilitates the parametric analysis and the derivation of important features of the system such as the frequency-amplitude relation associated to each nonlinear mode and resonance curves. The stability is analyzed by the Floquet theory. Bifurcation diagrams and Mathieu charts are used to identify the unstable regions in the force parameter space. The analytical results show good agreement with the numerical solution obtained by direct integration of the equation of motion.

Corporations

2020 ◽  
pp. 151-182
Author(s):  
Danny M. Adkison ◽  
Lisa McNair Palmer
Keyword(s):  
Natural Gas ◽  
Gas Production ◽  
Economic Life ◽  
Regulatory Control ◽  
Natural Gas Production ◽  
Motor Carriers ◽  
Cotton Gins ◽  
Oil And Natural Gas ◽  
Water Companies

This chapter examines Article IX of the Oklahoma constitution, which concerns the powers, limits, and regulation of corporations. The prodigious length of the article reflects the importance of corporations in the economic life of Oklahoma, and the determination of the framers to bring them under regulatory control, to the point of micromanagement. Concern about discriminatory rates charged by railroads and pipelines was foremost, but the authority conferred by Article IX is broad enough to allow the legislature to regulate a variety of other enterprises as well, including electric, gas, and water companies; oil and natural gas production; and conservation, cotton gins, motor carriers, telephone and telegraph lines; and even ice plants. The framers borrowed freely from the constitutions and statutes of other states—especially the Virginia constitution, the Texas constitution, and the Texas Railway Act—as models for Article IX. Whole sections were often copied verbatim. Moreover, often competing strains of waning Populism and rising Progressivism of the early 1900s pervade this article.

scholarly journals Application of a Developed Method for the Extraction of Triazines in Surface Waters and Storage Prior to Analysis to Seawaters of Galicia (Northwest Spain)

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Noelia Rodríguez-González ◽  
Elisa Beceiro-González ◽  
María José González-Castro ◽  
Soledad Muniategui-Lorenzo
Keyword(s):  
Solid Phase ◽  
Intermediate Precision ◽  
Simple Method ◽  
Oasis Hlb ◽  
Seawater Samples ◽  
The Stability ◽  
Optimized Conditions ◽  
And Storage ◽  
Surface Water Samples

A simple method based on solid-phase extraction combined with liquid chromatography for simultaneous determination of nine triazine herbicides (ametryn, atrazine, cyanazine, prometryn, propazine, simazine, simetryn, terbuthylazine, and terbutryn) in surface water samples was developed and validated. Under optimized conditions, 50 mL of water sample was pumped through the Oasis HLB cartridge, and triazines were eluted with 3 mL acetone. Finally the extract was concentrated to dryness, reconstituted with 1 mL methanol : water (1 : 1) and injected into the HPLC-DAD system. The stability of the herbicides on the cartridges at −18 and 4°C was also evaluated, and the recoveries obtained after three weeks of storage were satisfactory for all compounds. The analytical features of the proposed method were satisfactory: repeatability and intermediate precision were <10% and recoveries in spiked river water and seawater samples were higher than 93% for all compounds studied. Limits of quantification (varied from 0.46 to 0.98 µg L−1) were adequately allowing the determination of these compounds at the levels requested by the 2008/105/EC Directive. Finally, this method was applied to the analysis of 50 seawater samples from Galicia (northwest Spain).

Preparation, Stabilization and Some Properties of Purified Human Plasmin*

1964 ◽  
Vol 11 (01) ◽  
pp. 075-084 ◽  
Author(s):  
Daniel L Kline ◽  
Jacob B Fishman ◽  
Keyword(s):  
Plasminogen Activator ◽  
Stable Form ◽  
Neutral Ph ◽  
The Stability ◽  
And Storage

Summary1. Lysine increased the solubility, decreased the SK requirement and increased the stability of plasmin prepared from purified plasminogen by SK activation.2. A procedure is presented for the rapid and quantitative conversion of plasminogen to plasmin and storage of the plasmin in stable form at neutral pH as a lyophilized powder.3. Approximately 10% for the plasminogen molecule was split off during its activation. No carbohydrate was lost.4. The plasmin isolated was homogeneous in the ultracentrifuge at pH 2.5 and was quantitatively convertible to plasminogen activator by the addition of SK.

Resistance of cherry varieties to spring return frozes in the conditions of Astrakhan region

2020 ◽  
Author(s):  
A.A. Dronic A.A. ◽  
Keyword(s):  
Weather Conditions ◽  
Damage Score ◽  
The Stability ◽  
Almost All ◽  
Total Damage ◽  
Continental Climate ◽  
Unfavorable Weather

The article presents an assessment of the stability of introduced cherry varieties to spring return frosts in 2020 in the conditions of the sharply continental climate of the Astrakhan region. As a result of unfavorable weather conditions, the total damage score of all varieties was 2-5 points. Almost all the studied varieties showed an insufficient level of resistance to recurrent frosts.

Hydrological Response of a Patchy High Arctic Wetland

2000 ◽  
Vol 31 (4-5) ◽  
pp. 317-338 ◽  
Author(s):  
Kathy L. Young ◽  
Ming-ko Woo
Keyword(s):  
Weather Conditions ◽  
High Arctic ◽  
Ground Ice ◽  
Ice Melt ◽  
Snow Storage ◽  
Streamflow Response ◽  
Dry Seasons ◽  
And Storage ◽  
Surface And Subsurface Flow ◽  
Present Understanding

High Arctic patchy wetlands are ecological oases in a polar desert environment and are vulnerable to climatic warming. At present, understanding of their responses to external factors (climate and terrain) is limited. This study examines a wetland located in a topographic depression maintained by seasonal snowmelt, ground ice melt and lateral inflows. The wetland is located on Cornwallis Island, Nunavut, Canada. Hydrological, climatological and soil observations were made over several summers with different weather conditions. The summers of 1996 and 1997 were cool and wet but the summer of 1998 was warm and dry. The melt in 1996 was rapid due to rain on snow events and only lasted six days. Deeper snow in 1997 prolonged the melt season to 18 days. A shallow snow-cover in 1998 and early melt depleted the snow by early June. Surface, groundwater and storage fluctuations in the wetland were dictated by snowmelt, rainfall, evaporation loss from the wetland and lateral inputs which in turn were controlled by the melting of the late-lying snow storage in the catchment. Soil factors influence the spatial variations in ground thaw which affects the surface and subsurface flow. Streamflow response of the wetland reflects a nival regime and augmentation of streamflow thoughout the summer season in all three years is supported by multiple water sources: ground ice melt and suprapermafrost water from a large late-lying snowpack. Overall, this study suggests that the survival of some patchy wetlands depends on their interaction with the surrounding basin, with a dependency probably being more important during warm and dry seasons.

Determining the Norton’s Equivalent Model of Distribution System with Distributed Generation (DG) for Stability Analysis

2019 ◽  
Vol 12 (2) ◽  
pp. 190-198
Author(s):  
Sunny Katyara ◽  
Lukasz Staszewski ◽  
Faheem Akhtar Chachar
Keyword(s):  
Distributed Generation ◽  
Normal Condition ◽  
Distribution System ◽  
Distribution Networks ◽  
Equivalent Model ◽  
Stability Factor ◽  
Matlab Simulation ◽  
The Stability ◽  
Stability Issues

Background: Since the distribution networks are passive until Distributed Generation (DG) is not being installed into them, the stability issues occur in the distribution system after the integration of DG. Methods: In order to assure the simplicity during the calculations, many approximations have been proposed for finding the system’s parameters i.e. Voltage, active and reactive powers and load angle, more efficiently and accurately. This research presents an algorithm for finding the Norton’s equivalent model of distribution system with DG, considering from receiving end. Norton’s model of distribution system can be determined either from its complete configuration or through an algorithm using system’s voltage and current profiles. The algorithm involves the determination of derivative of apparent power against the current (dS/dIL) of the system. Results: This work also verifies the accuracy of proposed algorithm according to the relative variations in the phase angle of system’s impedance. This research also considers the varying states of distribution system due to switching in and out of DG and therefore Norton’s model needs to be updated accordingly. Conclusion: The efficacy of the proposed algorithm is verified through MATLAB simulation results under two scenarios, (i) normal condition and (ii) faulty condition. During normal condition, the stability factor near to 1 and change in dS/dIL was near to 0 while during fault condition, the stability factor was higher than 1 and the value of dS/dIL was away from 0.

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