Field lines

Pipelines are cleaned and inspected using pigs . Pigs usually have a steel body fitted with rubber cups and brushes or scrapers to remove wax and rust deposits on the pipe wall, as the pig is pumped along the pipe. Sometimes spherical pigs are used for product separation or controlling liquid hold up. In field lines handling untreated crude may have to be insulated to prevent wax formation. 

The representation of molecular properties on molecular surfaces is only possible with values based on scalar fields. If vector fields, such as the electric fields of molecules, or potential directions of hydrogen bridge bonding, need to be visualized, other methods of representation must be applied. Generally, directed properties are displayed by spatially oriented cones or by field lines. 

The problem with all the mirror approaches is that none has achieved the degree of confinement quaUty that the closed systems have. Closed systems ate characterized by magnetic field lines that close on themselves so that charged particles following the field lines remain confined within the system. 

This deleterious effect can be obviated by introducing additional components of magnetic field, causing the field lines to circumscribe the toms without ever closing on themselves. The net magnetic field is then composed of a major, or toroidal, field component produced by the current cods, plus a smaller poloidal component which gives the desired twist to the lines. Particle drifts weaken or nullify the harmful electrical field and the plasma no longer tends to move to the wads. 

The presence of a static magnetic field within a plasma affects microscopic particle motions and microscopic wave motions. The charged particles execute cyclotron motion and their trajectories are altered into heUces along the field lines. The radius of the helix, or the T,arm or radius, is given by the following ... 

In the simplest case of one-dimensional steady flow in the x direction, there is a parallel between Eourier s law for heat flowrate and Ohm s law for charge flowrate (i.e., electrical current). Eor three-dimensional steady-state, potential and temperature distributions are both governed by Laplace s equation. The right-hand terms in Poisson s equation are (.Qy/e) = (volumetric charge density/permittivity) and (Qp // ) = (volumetric heat generation rate/thermal conductivity). The respective units of these terms are (V m ) and (K m ). Representations of isopotential and isothermal surfaces are known respectively as potential or temperature fields. Lines of constant potential gradient ( electric field lines ) normal to isopotential surfaces are similar to lines of constant temperature gradient ( lines of flow ) normal to... 

Magnets with associated magnetic field lines. 

The n — 1 multiplet rule states that nuclei i and j will exhibit only Ji] and Wj lines. The two missing lines are the high field line of the low field multiplet and the low field line of the high field multiplet. In addition the intensity of emission and absorption over both multiplets balances as would be expected. For example, a high field E/A multiplet would at zero-field exhibit E and A n — 1 multiplets for nuclei i and j respectively. 

In the schematic the detector coil (hatched boxes) and its associated field lines are shown (dotted) and are seen to be always orthogonal to the permanent magnet field lines (solid). The magnitude of the static field is constant in the horizontal plane (thick black line). A stepper motor and gear-drives for raising the whole assembly relative to the external surface are visible in the photograph. 

Fig. 20. Electron spin resonance spectra of nitroxalkylcobalamin. (a) Spectrum before photolysis the high field line is broadened and therefore has a lower peak amplitude, (b) Expanded view of center line before photolysis showing no indication of additional hyperfine from methyl protons, (c) Spectrum of nitroxide photolysis product which has been freed from the cobalamin. (d) Expanded view of center line after photolysis now faintly showing proton hyperfine...

Fig. 21. Photolysis kinetics of nitroxalkylcobalamin. A 10-4 M solution was photo-lyzed aerobically in the spectrometer cavity. The increase in maximum intensity of the high field line is shown as a function of time...

As with the nitroxalkylcobalamins (119) and cobinamides, the co-binamides in which nitroxide is coordinated show electron spin resonance spectra very similar to the spectrum of free nitroxide. The high field line is not broadened as much as in the spectrum of a nitroxalkyl-cobinamide. No hyperfine splitting from methyl protons in the 2 or 6 positions can be observed for the bound nitroxide. However, treatment of the coordinate spin labeled compounds with cyanide releases the nitroxide. When this happens, the proton hyperfine can be observed (Fig. 25). Thus treatment with cyanide simply displaces the nitroxide and a spectrum for free nitroxide is observed. 

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