Experimental Results on the Combined 1st and 2nd Order Dynamics of a Small-Scale Taut-Leg Mooring Line

2005 ◽  
Author(s):  
Alexandre N. Simos ◽  
Andre´ L. C. Fujarra ◽  
Fa´bio G. Palazzo
Keyword(s):  
Second Order ◽  
Experimental Results ◽  
Mooring Line ◽  
Small Scale ◽  
Experimental Paradigm ◽  
Current Profile ◽  
Mooring Lines ◽  
Towing Tank ◽  
Calibration And Validation ◽  
First Order

A set of experimental results on the dynamics of taut-leg mooring-lines was generated by means of towing-tank tests. These results will be employed by Petrobras as an experimental paradigm for the calibration and validation of numerical codes based on finite-elements method (FEM). The setup allowed combining first and second order motions on the top of the line with different amplitudes and frequencies. The first order motions were emulated by means of circular harmonic motions while alternate horizontal translations represented the drift motions. It was also possible to emulate a uniform in-plane current profile along the suspended length of the model. The model was composed by three different segments. An intermediate rubber hawser connected the top and anchor chain segments and allowed considerable elongation of the line during the tests. Tension at the top of the model was measured by means of a load cell and the second-order motion was registered optically. This paper presents the procedure adopted for the tests and also some preliminary comparisons between experimental results and numerical simulations.

A Percolation Equation for Modeling Experimental Results for Continuum Percolation Systems

2001 ◽  
Vol 699 ◽  
Author(s):  
D.S. McLachlan ◽  
C. Chiteme ◽  
W.D. Heiss ◽  
Junjie Wu
Keyword(s):  
Experimental Data ◽  
Ac Conductivity ◽  
Volume Fraction ◽  
Power Laws ◽  
Second Order ◽  
Experimental Results ◽  
Analytical Equation ◽  
Scaling Properties ◽  
First Order ◽  
Dc And Ac Conductivity

AbstractThe standard percolation equations or power laws, for dc and ac conductivity (dielectric constant) are based on scaling ansatz, and predict the behaviour of the first and second order terms, above and below the percolation or critical volume fraction (øc), and in the crossoverregion. Recent experimental results on ac conductivity are presented, which show that these equations, with the exception of real σm above øc and the first order terms in the crossover region, are only valid in the limit σi/σc = 0, where for an ideal dielectric σi=ωε0εr.A single analytical equation, which has the same parameters as the standard percolation equations, and which, for ac conductivity, reduces to the standard percolation power laws in the limit σi(ωε0εr)/σc = 0 for all but one case, is presented. The exception is the expression for real σm below øc, where the standard power law is always incorrect. The equation is then shown to quantitatively fit both first and second order dc and ac experimental data over the entire frequency and composition range. This phenomenological equation is also continuous, has the scaling properties required at a second order metal-insulator and fits scaled first order dc and ac experimental data. Unfortunately, the s and t exponents that are necessary to fit the data to the above analytical equation are usually not the simple dimensionally determined universal ones and depend on a number of factors.

Coulomb interaction energy including overlap effects for the ground state of RbCs beyond 7 Å

1996 ◽  
Vol 74 (3-4) ◽  
pp. 155-158
Author(s):  
K. Hussein
Keyword(s):  
Interaction Energy ◽  
Coulomb Interaction ◽  
Configuration Space ◽  
Ground State ◽  
Present Method ◽  
Second Order ◽  
Experimental Results ◽  
Coulomb Energy ◽  
First Order ◽  
Dispersion Terms

We use a perturbative model based on a partition of the configuration space into four regions to calculate the Coulomb energy including charge-overlap effects (induction and dispersion terms) for the interaction between two atoms Rb(5s2S) and Cs(6s2S). Results for first-order electrostatic as well as second-order induction and dispersion energies will be presented in the range 13 < R < 25 a.u. The damping functions for the various dispersion terms varying as R−6, R−8, and R−10 in the range of large R have also been determined, and fitted analytical forms will be displayed for these terms. From comparison with accurate experimental results, the present method is seen to be valid for values of R beyond 7 Å (1 Å = 10−10 m).

Fracture Mechanics Based Mooring Fatigue Analysis for a Semi-Submersible Subjected to Triple Narrow-Band Loading Processes

2019 ◽  
Author(s):  
Xutian Xue ◽  
Nian-Zhong Chen ◽  
Yongchang Pu
Keyword(s):  
Fatigue Life ◽  
Fracture Mechanics ◽  
Fatigue Analysis ◽  
Second Order ◽  
Combination Method ◽  
Mooring System ◽  
Initial Surface ◽  
Loop Current ◽  
Mooring Lines ◽  
First Order

Abstract In the general offshore operating locations, mooring systems are normally considered to be primarily affected by environmental loadings induced by waves, wind and current. WF motion induced by first-order waves, LF motion induced by second-order waves and wind would make the most contribution to the fatigue damage of mooring lines. However, it was reported recently that in the Gulf of Mexico (GoM), the fatigue life of mooring lines can be significantly affected by the vortex induced motion (VIM) induced by loop current. The aim of this presented paper is to address the influence of VIM on fatigue life of the mooring system operating at the central of the GoM through performing a fracture mechanics (FM) based fatigue analysis for an offshore mooring system. A frequency-domain mooring analysis for the semi-submersible is conducted where WF motion induced by first-order waves, LF motion induced by second-order waves and wind, and VIM induced by loop current are taken into account. WF motion, LF motion and VIM are treated as three independent loading processes. A wide-band loading combination method is then used for predicting the loading processes acting on the mooring system combining WF motion, LF motion and VIM. A fracture mechanics based analysis is performed to examine the fatigue life of mooring system, in which initial surface cracks in previous existence are assumed to grow from the surfaces of mooring chain links connecting to the fairleads. The stress intensity factor ranges to estimate the crack growth in the FM based analysis are obtained from a finite element (FE) analysis.

Species associations of congeneric species in a tropical seasonal rain forest of China

2016 ◽  
Vol 32 (3) ◽  
pp. 201-212 ◽  
Author(s):  
Guoyu Lan ◽  
Yunbing Zhang ◽  
Fangliang He ◽  
Yuehua Hu ◽  
Hua Zhu ◽  
...  
Keyword(s):  
Species Interactions ◽  
Rain Forest ◽  
Biotic Interactions ◽  
Second Order ◽  
Small Scale ◽  
Order Effects ◽  
Congeneric Species ◽  
First Order ◽  
Large Trees ◽  
Tropical Seasonal Rain Forest

Abstract:In tropical plant communities with diverse species, many congeners are found to coexist. Do environment or biotic interactions structure the coexistence of congeners in tropical forest communities? In this paper, we aimed to disentangle the effect of environment (first-order effects) and species interactions (second-order effects) on the spatial distributions of tree species. We used a classification scheme and torus-translation to test the first-order interaction of 48 species from 17 genera in a fully mapped 20-ha dipterocarp tropical seasonal rain-forest plot in Xishuangbanna, south-west China. Then we used heterogeneous Poisson null models to reveal significant uni- and bivariate second-order interactions. The results demonstrated that (1) 34 of the 48 studied species showed a significant relation with at least one topographic variable. This confirmed that topographical heterogeneity is important for distribution of these congeners. Spatial segregation (36.6%) and partial overlap (34.8%) were the most common bivariate association types in Xishuangbanna plot, which indicated first-order effects (environment) were strong. (2) For small-scale associations, 51% saplings (1 to ≤ 5 cm) (68.8% for large trees with dbh > 5 cm) of the species showed non-significant associations. For large-scale associations, 61.6% saplings (81.2% for large trees) of the species showed non-significant associations. Lack of significant species interactions provides evidence for the unified neutral theory. In conclusion, both environment and biotic interactions structure congeneric species' coexistence in tropical seasonal rain forest in this region.

scholarly journals Localized Conical Edge Modes of Higher Orders in Photonic Liquid Crystals

Crystals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 542 ◽  
Author(s):  
Vladimir A. Belyakov ◽  
Sergei V. Semenov
Keyword(s):  
Liquid Crystals ◽  
Maxwell Equations ◽  
Analytic Solution ◽  
Second Order ◽  
Experimental Results ◽  
Analytical Theory ◽  
Exact Analytic Solution ◽  
Localized Modes ◽  
First Order ◽  
Order Diffraction

Most studies of the localized edge (EM) and defect (DM) modes in cholesteric liquid crystals (CLC) are related to the localized modes in a collinear geometry, i.e., for the case of light propagation along the spiral axis. It is due to the fact that all photonic effects in CLC are most pronounced just for a collinear geometry, and also partially due to the fact that a simple exact analytic solution of the Maxwell equations is known for a collinear geometry, whereas for a non-collinear geometry, there is no exact analytic solution of the Maxwell equations and a theoretical description of the experimental data becomes more complicated. It is why in papers related to the localized modes in CLC for a non-collinear geometry and observing phenomena similar to the case of a collinear geometry, their interpretation is not so clear. Recently, an analytical theory of the conical modes (CEM) related to a first order of light diffraction was developed in the framework of the two-wave dynamic diffraction theory approximation ensuring the results accuracy of order of δ, the CLC dielectric anisotropy. The corresponding experimental results are reasonably well described by this theory, however, some numerical problems related to the CEM polarization properties remain. In the present paper, an analytical theory of a second order diffraction CEM is presented with results that are qualitatively similar to the results for a first order diffraction order CEM and have the accuracy of order of δ2, i.e., practically exact. In particular, second order diffraction CEM polarization properties are related to the linear σ and π polarizations. The known experimental results on the CEM are discussed and optimal conditions for the second order diffraction CEM observations are formulated.

Three-Dimensional Dynamic Analysis Method of Multi-Component Mooring Lines

2019 ◽  
Author(s):  
Yuda Apri Hermawan ◽  
Yoshitaka Furukawa
Keyword(s):  
Dynamic Analysis ◽  
Numerical Method ◽  
Three Dimensional ◽  
Experimental Results ◽  
Mooring Line ◽  
Lumped Mass ◽  
Mooring Lines ◽  
Dynamic Behaviors ◽  
Component Object ◽  
Deep Depth

Abstract Complicated mooring system well-known as a multi-component mooring line is highly required owing to the deep depth of water and severe sea conditions. Since the dynamic behaviors of such mooring line are quite complex, proper numerical method is indispensable to predict the dynamic behaviors of a multi-component mooring line efficiently and precisely. In this paper, a numerical method improving the lumped mass method is proposed to introduce the three-dimensional dynamic analysis of multi-component mooring line with the motion of an anchor and clump weights. The mooring line is regarded as a multi-component object which has nonuniform segment line characteristics. In this method, lumped mass technique is developed to represent the three-dimensional dynamic behavior of each segment individually, allowing the motion of bottom-end segment as well as the anchor. Then, the motion of the end-segment is regarded as the motion of the upper-end of lower segment. Meanwhile, calculation method of initial condition for dynamic calculation is developed by adopting the basic principle of multi-component mooring line catenary equations. The results of time histories representing the three-dimensional dynamic analysis of mooring line are obtained and compared with other numerical and experimental results presented in published papers. The results show good agreement with both numerical and experimental results.

Study on Adsorption Property of Collagen Fiber Loaded Hyperbranched Polyamide-Amine Toward Cr (VI)

2012 ◽  
Vol 610-613 ◽  
pp. 514-517 ◽  
Author(s):  
Xue Chuan Wang ◽  
Fei Fei Zhang ◽  
Tao Tao Qiang
Keyword(s):  
Collagen Fiber ◽  
Adsorption Process ◽  
Adsorption Property ◽  
Second Order ◽  
Experimental Results ◽  
Order Model ◽  
First Order ◽  
Before And After ◽  
Pseudo Second Order ◽  
Hyperbranched Polyamide

Collagen fiber loaded hyperbranched polyamide-amine(CF-HBPN) was prepared by the crosslinking power of glutaraldehyde. The structure of CF-HBPN before and after adsorption was characterized and analyzed via scanning electron microscopy. The CF-HBPN was effective adsorbent for the removal of Cr(VI) from aqueous solutions. The adsorption isotherm and kinetic of the adsorption process were studied. The experimental results were fitted using the Langmuir, Freundlich and Temkin equations. The experimental results indicated that the Langmuir isotherm was better in describing the adsorption process. Two kinetic models, the pseudo-first order and pseudo-second order, were used to analyze the kinetic data. The pseudo-second order model was proven to be better in describing the adsorption behavior.

Frequency Domain Analysis of a Deepwater Monobuoy and Its Mooring

2003 ◽  
Author(s):  
Antonio C. Fernandes ◽  
Andre´ L. S. Lima ◽  
Carlos A. F. Oliveira
Keyword(s):  
Computer Program ◽  
Frequency Domain ◽  
Ad Hoc ◽  
Diffraction Theory ◽  
Frequency Domain Analysis ◽  
Mooring Line ◽  
Mooring Lines ◽  
Restoring Force ◽  
First Order ◽  
Frequency Domain Approach

The paper addresses a CALM (catenary anchor leg mooring) monobuoy arrangement. There are several monobuoys installed in deeper waters from 400 m to 1000 m or more. This increases the mooring line effects on the first order monobuoy behavior, and unlike the much larger drilling and production platforms they cannot be neglected. As shown, in a frequency domain approach, it is possible to devise restoring force effects, damping effects and even inertial ones. Hence, the full understanding of the behavior is only reached if the mooring lines are properly considered. Model tests, an ad hoc linear diffraction theory computer program (ProMono) and a fully nonlinear time domain computer program are used in the analysis.

Oceanographic and Motion Response Statistics for the Operation of a Weathervaning LNG FPSO

2003 ◽  
Author(s):  
Kevin Ewans ◽  
Clemens van der Valk ◽  
Christopher Shaw ◽  
Joost den Haan ◽  
Peter Tromans ◽  
...  
Keyword(s):  
Mooring Line ◽  
Current Profile ◽  
Mooring Lines ◽  
Motion Response ◽  
Response Data ◽  
Oceanographic Data ◽  
One Year ◽  
Vessel Motion ◽  
High Level ◽  
Inertial Currents

An oceanographic database is used to estimate the operability of a weathervaning LNG FPSO (FLNG) in multidirectional seas with swells. The oceanographic data consist of directional wave data, current profile measurements, and a wind dataset. Response functions are used to convert the oceanographic data into an equivalent dataset of vessel motion response parameters and turret mooring line tensions. The resulting response data have enabled operational type statistics to be computed, as well as the environmental conditions that induce responses with a one-year return period. In addition to the analysis of the responses of the FLNG alone, the method has been applied to a system where a LNG shuttle carrier is moored alongside the FLNG for offloading of the products. In this case, important responses are the combined roll and pitch of the two vessels and tension in the mooring lines between the shuttle carrier and the FLNG. The same method can be applied for a stern-to-bow offloading system, where the shuttle carrier is moored with a hawser or soft yoke. The diversity of the directionality of the oceanographic variables makes this a particularly interesting exercise. The analysis included significant inertial currents, a high level of background swell and frequent local-wind seas that act at an angle to the prevailing swell direction. A method for separating a sea state into a sea and swell component has been derived and is reported, along with a programme for visualising the oceanographic conditions together with the induced responses corresponding to the existing conditions.

Gradient based first- and second-order filters for the demarcation of continental–oceanic boundaries using satellite gravity data

2020 ◽  
Vol 221 (3) ◽  
pp. 1499-1514
Author(s):  
Ved P Maurya ◽  
Sergio L Fontes ◽  
Vanderlei C Oliveira Jr ◽  
Emanuele F La Terra
Keyword(s):  
Energy Content ◽  
Gravity Data ◽  
Regional Scale ◽  
Inverse Correlation ◽  
Second Order ◽  
Geochemical Data ◽  
Spectral Energy ◽  
Small Scale ◽  
Satellite Gravity ◽  
First Order

SUMMARY Demarcating the continental–oceanic boundary (COB) is extremely important as it contributes to an understanding of the tectonic environments of marginal basins through plate reconstructions. In general, the COB is estimated by jointly interpreting the features of the basement geomorphology, bathymetry and geophysical datasets, including gravity, magnetic, seismic and geochemical data. We propose a novel methodology named the tilt-theta angles correlation (TTAC), a second-order filtering approach to estimate the COB using high-resolution satellite gravity data. This method computes the angular difference or correlation angle between the vectors computed from the gradients of the tilt and theta derivative-based first-order filters. Oceanic regions generally exhibit small correlation angles (∼0°), thereby indicating a direct correlation; in contrast, continental regions depict large correlation angles (∼180°) and thus display an inverse correlation. The TTAC method marks the COB at the spatial position where the correlation angles abruptly shift from inverse to direct. Tests using synthetic data and the larger spectral energy content of TTAC for long wavelengths over tilt, theta and minus of the sign of vertical derivative (-SiVD) filters attest the effectiveness of the new methodology over first-order derivative based filters. Additionally, tests utilizing real data over both the West African Transform Margin (WATM) and across the South Atlantic Conjugate Margin (SACM) provide favourable results compared with the previous methodologies used to demarcate the COB. The COB estimates derived using the new methodology are consistent with the COB estimates obtained during recent plate-reconstruction studies. We also compare our results with an earlier interpretation along a conjugate margin encompassing magma-poor and magma-rich regions. In the complex rifted environments of the SACM, in which volcanic rocks are dominant, the TTAC methodology substantially improves the previous COB estimates, thereby establishing it as an efficient edge marker by simultaneously reducing small-scale geological noise and enhancing regional-scale geological contributions.

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