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Collaborating Authors
- North America > United States > Wyoming (0.41)
- North America > United States > Montana (0.41)
- North America > United States > Wyoming > Powder River Basin (0.99)
- North America > United States > Montana > Powder River Basin (0.99)
Ground roll noise on land data sets overwhelms the desired reflection seismic signal unless special steps are taken in data acquisition and processing to control it. This is usually done in the field by the design of group arrays for data acquisition. On the other hand, if multicomponent data are acquired, it is possible to remove ground roll during processing using polarization analysis. Even though this processing is computationintensive, the potential exists for obtaining results similar to conventional data acquisition, but with deployment of fewer sensors in the field with minimal group array effects. It also has potential for deriving new information. We describe a twodimensional polarizationfilter analysis for use with vertical and inline sensors. A timedomain spectral matrix technique is developed since the recorded seismic signal is the superposition of multiple signals in the time domain, each with different frequency content and timevarying polarization. This technique is implemented by decomposing the signal into individual frequency components using narrow bandpass filters and defining the polarization characteristic using sliding time windows. We show that both incoherent noise and specific linearly polarized constituents can be successfully filtered.
ABSTRACT With the ever expanding size of VLCC's and their increased frequency of berthing single point mooring buoys, mooring loads are substantially increased. These larger loads are placing greater demands on mooring hawsers. Such loads necessitate larger and stronger ropes or complicated and inefficient rope systems, should smaller ropes be used. Load monitoring is an effective method of not only decreasing the risk of failure, but it can also be cost effective by increasing mooring hawser service life. INTRODUCTION During January 1971, Continental oil commenced operating a conventional single point mooring in the Humber River - on the East Coast of England bordering the North Sea. The S.P.M. was installed in the estuary of the Humber in a location where the currents reach peak velocities of 3 1/2 knots. The low water depth is 60 feet with a tidal range of up to 25 feet. The' initial buoy to ship hawser system utilized twin 12 inch circumference lines, each 140 feet long and connected to a triangle at the S.P.M., with twin 2 inch diameter by 15 foot long chafing chains at the ship end of the nylon. Ten inch circumference polypropylene pick-up ropes were then connected to the chafing chain,' the port rope being 300 feet long and the starboard rope being 150 feet long. The port rope, being longer, was always picked up first. During the first few berthings, the tanker was secured to the chafing chain by nylon strops, but this was later changed to 1 5/8 inch diameter wire rope. The nylon lines were supported with small individual cylindrical hawser floats and the chafing chain with large steel spherical buoys which were attached to the chafing chain by wire strops. Because the S.P.M. was located close to a holiday beach and nature reserve, it was considered absolutely essential to take very stringent safety precautions, and ropes were changed out at frequent intervals to avoid unnecessary risks. PROBLEM AREAS Some problems occurred due to the chain support buoys fouling with the ropes, as well as with each other. To remove the source of this problem, Dunlop Company (whose hose manufacturing plant is nearby) was asked to produce a steel cylinder covered with hose flotation material which would be capable of supporting the chafing chain. The chain support buoy was produced in due course and the chafing chain threaded through the steel pipe in the center of the buoy in order to provide the necessary flotation. This system removed the problem of the rope tethers fouling each other when they were floating free. Because the S.P.M. was located in a tidal area, the mooring hawsers were susceptible to abrasion against the sharp edges of the buoy during every tide change. It was obvious that some form of protection was required and the Dunlop Company was again approached and asked to produce rope flotation collars which would not only float the rope, but also protect it against abrasion. Dunlop devised a plan for the use of rope floats manufactured from their hose flotation material in 10 foot lengths.
- North America > United States > Texas (0.28)
- Europe > United Kingdom > North Sea (0.24)
- Europe > United Kingdom > England (0.24)
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- Energy > Oil & Gas > Upstream (0.94)
- Transportation > Marine (0.90)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (0.34)
Acoustic emission (AE) nondestructive evaluation characterizations have been obtained from new Samson double-braided 2-in-1, 0.635-cm-diameter (¼ in.) nylon rope in the dry condition at room temperature. A parameter called the "AE load delay" has been defined as the tensile load required to produce a specified low baseline level of AE activity. It has been observed that the AE load delay can be correlated with the ultimate rupture load of the rope with cut core yarns and with a variety of stress-concentrating knots.
This abstract will examine in detail the two potential pitfalls Numerous applications in exploration geophysics and remote of using EM systems on a UAS by presenting experimental results sensing have been proposed for unmanned aircraft systems for noise measurements with a frequency-domain instrument (UASs), which have less operating cost and risk, as well as the alongside a rotary-wing UAS and by discussing the payload potential to offer data of higher resolution than conventional restrictions. Results were recently published from a semiairborne airborne platforms. Using UASs as platforms for electromagnetic system used to perform a time-domain EM survey to (EM) geophysical surveying is uncommon--magnetics delineate a massive sulfide (Legault, 2015; Yang and Oldenburg, and radiometrics, both passive systems, are overwhelmingly 2016). This semi-airborne system used a large groundbased more common as geophysical payload for such aircraft. There inductive loop together with a receiver mounted on a are two significant challenges when porting EM methods to manned helicopter. The discussion will conclude by proposing UASs: noise and payload mass. A series of noise measurements a similar semi-airborne system where the receiver is instead on are shown, which show that interference from the UAS a UAS.
- Aerospace & Defense > Aircraft (1.00)
- Energy > Oil & Gas > Upstream (0.68)