Satellite Collision Probability for Non-Linear Relative Motion

2002 ◽  
Author(s):  
Russell Patera
Keyword(s):  
Relative Motion ◽  
Collision Probability ◽  
Non Linear

Comparative Analysis of non-linear position variations using the time series of station coordinates in some ITRF co-location sites

2020 ◽  
Author(s):  
Lizhen Lian ◽  
Chengli Huang ◽  
Jin Zhang
Keyword(s):  
Time Series ◽  
Comparative Analysis ◽  
Relative Motion ◽  
Time Variable ◽  
Accurate Estimation ◽  
Station Coordinates ◽  
Non Linear ◽  
The Future ◽  
Seismic Deformation

<p>The reprocessed time series (weekly from SLR, daily from GNSS, and 24h session-wise from VLBI) of co-located station position solutions spanning their full observation histories up to the end of 2014 are analyzed with the goal to detect nonlinear time-variable effects in station positions, such as periodic variations or discontinuities caused e.g. by instrumental changes or earthquakes. This information is then used to assess the reliability of the results about the nonlinear changes of all technique stations in each colocation site since they can be verified with each other. Next, the iterative adjustment is performed, i.e. jumping changes, post-seismic deformation and periodical signals are determined altogether for accurate estimation of station velocity. Finally, the information of the relative motion among the stations equipped with different technique instruments per colocation site is determined which can offer a reference for the necessary arrangement of local resurvey in the future.</p>

scholarly journals Evaluation of collapse mechanisms in masonry buildings: critical overview and case histories

Alternativas ◽  
2017 ◽  
Vol 17 (3) ◽  
pp. 76-83
Author(s):  
Angelo Di Tommaso ◽  
Susanna Casacci
Keyword(s):  
Relative Motion ◽  
Seismic Vulnerability ◽  
Masonry Buildings ◽  
Analytical Evaluation ◽  
Case Histories ◽  
Collapse Mechanisms ◽  
Non Linear ◽  
Analytical Procedures ◽  
Critical Overview

In recent years the approach to the analysis of seismic vulnerability of masonry buildings considers as crucial the evaluation of potential local mechanisms. The “fracture” lines depicted on the wall (when it is “compact”) can show its labile condition of equilibrium and point out the potential kinematic of relative motion among blocks. The analytical evaluation of kinematics, linear and non-linear, presents some aspects that could be analysed with criticism.Among the techniques to contrast the potential mechanisms some very effective ones could be considered: plating with composites (covered by plaster) or reinforced re-pointing.Basic criteria to apply it and analytical procedures to determine the level of upgrading are considered in detail.This paper will analyse some of these aspects with reference to actual cases of study (Pavarotti theatre and San Barnaba Church in Modena, and campanile in Reno Centese, Ferrara, Italy).

Structural Design and Validation of Prelude’s Marine Loading Arms

2020 ◽  
Author(s):  
Erwan Auburtin ◽  
Eric Morilhat ◽  
Stéphane Paquet ◽  
Abdeslam Raissi ◽  
Ewoud van Haaften ◽  
...  
Keyword(s):  
Natural Gas ◽  
Relative Motion ◽  
Structural Design ◽  
Liquefied Natural Gas ◽  
Scale Model ◽  
Base Case ◽  
Liquefied Petroleum Gas ◽  
Dynamic Conditions ◽  
Wave Basin ◽  
Non Linear

Abstract Prelude Floating Liquefied Natural Gas (FLNG) facility reached a significant milestone in June 2018 when gas was introduced onboard for the first time as part of the facility startup process, loaded from an LNG carrier moored in side-by-side (SBS) configuration. This first offshore LNG SBS operation allowed Prelude’s utilities to switch from running on diesel to running on gas. SBS mooring is the base case configuration for of floading both LNG and Liquefied Petroleum Gas (LPG) into product carriers using Marine Loading Arms (MLA) once the Prelude FLNG facility is fully operational. These complex and weather sensitive operations are expected to take place on a weekly basis. This means critical decisions about weather-window and timing should be supported as much as possible by predictive analysis and modelling of environment forecasts to reduce the risks. Prelude Floating Liquefied Natural Gas (FLNG) is designed to offload Liquefied Natural Gas (LNG) and Liquefied Petroleum Gas (LPG) to carrier vessels moored in a side-by-side (SBS) configuration, using Marine Loading Arms (MLA) technology. For onshore terminals or small/medium FLNG, the traditional design of MLA (Double Counterweight Marine Arm – DCMA), featuring a vertical riser, can be used. However due to the exceptional freeboard of Prelude a new type of MLA was designed, namely the Offshore Loading Arm Footless (OLAF), without vertical riser in order to reach the LNG or LPG manifolds located as far as about 16 meters below the MLA base. Thanks to the OLAF design, the length and weight of the articulated MLA sections is reduced in comparison with conventional DCMA, and so are the dynamic loads applied by the MLA on the vessel manifold, which was mandatory to remain below the acceptable stress limit of standard LNG/LPG carrier manifolds. OLAF employs the field proven targeting system (TS) allowing the connection and disconnection of the MLA to the vessel manifold in dynamic conditions. This paper describes the assumptions and process to design and validate this new system — in terms of overall geometry and structural design, while verifying project feasibility, aiming at a reliable design of all components and minimizing the risks during operations. The key challenges and lessons learnt are also discussed. This innovative type of MLA had to be thoroughly designed and tested before being manufactured and assembled on the FLNG. The innovation management was also coupled with the additional challenge imposed by the expected highly dynamic conditions of relative motion between vessels that were never encountered for such systems in the past. MLA were designed with the objective to cover the operable envelope induced by berthing, mooring and relative motion criteria, so that it should not become an additional criterion in general. Since such an envelope is larger for this offshore application compared to sheltered terminals, this objective was particularly challenging but could be met thanks to the OLAF design. The SBS hydrodynamic numerical model is based on potential theory and includes multi-body coupling, non-linear mooring characteristics and coupling with sloshing. This model was calibrated using wave basin tests with a good agreement, and was used to determine the maximum operable environments and associated MLA envelope, using a 39-year hindcast for various LNG carriers and considering a scenario with different criteria and loading conditions. More than 100,000 time-domain simulations were required to evaluate non-linear quantities on a reduced set of environment ‘bins’. The new OLAF-type MLA was developed using these hydrodynamic simulations. Specific processes — based on spectral screening and selection using relevant criteria — were used to identify and select, in a systematic way, the designing load cases for connecting, connected, and emergency disconnection cases, while complying with the maximum allowable loads of conventional LNG and LPG carrier manifolds. An instrumented 1:4 OLAF scale model was built and tested with 6 degrees of freedom hexapods reproducing the motions on both sides of the OLAF which enabled us to confirm a 10% accuracy of the numerical studies results. The actual OLAF were dynamically tested with a full scale motion simulator before shipment to the yard for installation. The successful first operations were performed safely and confirmed the validity of the design. Measurements are now collected onboard Prelude to verify the design and when possible improve the accuracy of numerical modelling.

B. The Non-Linear Calculations for Pulsating Stars

1967 ◽  
Vol 28 ◽  
pp. 105-176
Author(s):  
Robert F. Christy
Keyword(s):  
Major Part ◽  
Afternoon Session ◽  
Discussion Session ◽  
Pulsating Stars ◽  
Fourth Symposium ◽  
Non Linear ◽  
Considerable Discussion ◽  
Informal Approach ◽  
Preceding Session

(Ed. note: The custom in these Symposia has been to have a summary-introductory presentation which lasts about 1 to 1.5 hours, during which discussion from the floor is minor and usually directed at technical clarification. The remainder of the session is then devoted to discussion of the whole subject, oriented around the summary-introduction. The preceding session, I-A, at Nice, followed this pattern. Christy suggested that we might experiment in his presentation with a much more informal approach, allowing considerable discussion of the points raised in the summary-introduction during its presentation, with perhaps the entire morning spent in this way, reserving the afternoon session for discussion only. At Varenna, in the Fourth Symposium, several of the summaryintroductory papers presented from the astronomical viewpoint had been so full of concepts unfamiliar to a number of the aerodynamicists-physicists present, that a major part of the following discussion session had been devoted to simply clarifying concepts and then repeating a considerable amount of what had been summarized. So, always looking for alternatives which help to increase the understanding between the different disciplines by introducing clarification of concept as expeditiously as possible, we tried Christy's suggestion. Thus you will find the pattern of the following different from that in session I-A. I am much indebted to Christy for extensive collaboration in editing the resulting combined presentation and discussion. As always, however, I have taken upon myself the responsibility for the final editing, and so all shortcomings are on my head.)

The restoration of blurred electron micrographs

1986 ◽  
Vol 44 ◽  
pp. 180-181
Author(s):  
Bridget Carragher ◽  
David A. Bluemke ◽  
Michael J. Potel ◽  
Robert Josephs
Keyword(s):  
Cross Section ◽  
Electron Micrographs ◽  
Relative Motion ◽  
Finite Thickness ◽  
Image Plane ◽  
Helical Axis ◽  
Thin Sections ◽  
Structural Details

We have investigated the feasibility of restoring blurred electron micrographs. Two related problems have been considered; the restoration of images blurred as a result of relative motion between the specimen and the image plane, and the restoration of images which are rotationally blurred about an axis. Micrographs taken while the specimen is drifting result in images which are blurred in the direction of motion. An example of rotational blurring arises in micrographs of thin sections of helical particles viewed in cross section. The twist of the particle within the finite thickness of the section causes the image to appear rotationally blurred about the helical axis. As a result, structural details, particularly at large distances from the helical axis, will be obscured.

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