String dynamics

Semi-submersible rigs are often referred to as semis , and are a floating type of rig. Like the jack-up, a semi is self contained. The structure is supported by large pontoons which are ballasted with water to provide the required stability and height. The rig is held in position by anchors and mooring lines or dynamically positioned by thrusters. A large diameter steel pipe ( riser ) is connected to the sea-bed and serves as a conduit for the drill string. The blowout preventer (BOP) is also located at the sea-bed ( sub sea stack ). 

Much confusion exists as to the best choice of lubricant additives for a given situation. Evaluation both in the laboratory and in the field is difficult because of the dynamic nature of the drilling fluid and the wide range of factors that influence drill string torque and drag. Liquid lubricants are used at concentrations of 0.25—4 vol %, soHd materials at ca 6—29 kg/m (2—10 Ib/bbl). 

For dynamic conditions, find the total load on a derrick that is capable of lifting a 600,000-lb drill string with an 8-working line block and tackle. The crown... 

Universality in Unimodal Maps A seminal work on the 2-symbol dynamics of one-dimensional unimodal mappings due to Metropolis, Stein Stein [metro73]. Specifically, they studied the iterates of various mappings within periodic windows, labeling the attractor sequences by strings of the form RLLRL , where R and L indicate whether f xo) falls to the right or left of xq, respectively. Each periodic sequence therefore corresponds to a unique finite length word made up of R s and L s. 

From this first example, it is obvious that, apart from a CA-like pai allel updating of an ever-increasing number of sites and the set of recursive symbol-strings to which such a dynamics inevitably leads, there is no real internal geometry, as such. Each string at time t remains essentially a static collection of abstract symbols. 

Algorithmic Complexity Dynamic Measures complexity of given string vice ensemble Hard to compute complexity equated with randomness... 

Logical Depth Dynamic Random strings are shallow, matching intuition Hard to apply to physical systems... 

Garrahan and Chandler [230] have recently attempted to rationalize the string-like motion in supercooled liquids based on a completely different concept of dynamic facilitation, derived from the study of magnetic spin models originally developed by Fredrickson and Anderson [231]. Although these spin models seem to exhibit dynamic heterogeneity of some kind and slow relaxation processes, the slowing down of the dynamics in these models is entirely decoupled from the spin model s thermodynamics [116, 230]. In view... 

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