Pinning field

If the vortex population is pinned so that it is not in equilibrium with the applied field, then the M-H curve takes the irreversible route as illustrated. The pinned vortices contribute an M in the same sense as the applied H since they are the penetrated field, and as the applied field is reduced the +M manifests itself just as it does for an ordinary permanent magnet. The pinned field is aptly described as the trapped field . 

Fig. 6.24. Schematic hysteresis loops in a material where magnetisation reversal occurs by (a) domain wall unpinning, and (b) by domain nucleation. H and Hp are the nucleation and pinning fields, respectively.

The hot-air knife, as previously described, is sometimes useful in removing unwanted solder bridges from between component leads while the solder is still molten. This is especially useful in connectors and PGAs with interstitially arrayed pin fields (see Fig. 47.24). 

Prior to insertion into the board, check press-fit connector pins for straightness and integrity. An inexpensive go/no-go gauge (see Fig. 49.14) can be machined to check that connector pins are not bent. It should be constructed so that it neither compresses the compliant section of the press-fit pin nor damages its surface coating. This is especially helpful for fine-pitch press-fit connectors (1 mm centers) and is better than relying on visual inspection for pin field integrity. 

We now consider the formulation of the equations of motion for a rigid body pinned at its center of mass and acted on by a (possibly nonlinear) potential field. The Lagrangian in this case is... 

As the final part of the repair proeess, the expander underwent a trial assembly at the repair faeility. The aetual job assembly and disassembly fixtures were used during the trial assembly. No signi-fieant problems were eneountered and internal elearanees were to speeifieations. As the assembly bed plate at the repair faeility did not exaetly duplieate the user s baseplate, there was some eoneern that readjustment would be required in the field to obtain elearanees. To faeilitate the field assembly proeess, appropriate pins and fixtures were manufaetured to hold axial and eoneentrie positions of the diffuser and stator as they were in die repair shop. The entire expander trial assembly was eompleted one mondi ahead of sehedule. 

Fig. 4.7. A semiconductor detector operated as a pin diode with a reverse voltage or bias. An incident X-ray photon ultimately produces a series of electron-hole pairs. They are "swept out" by the bias field of-500 V- electrons in the direction ofthe n-layer holes in the direction ofthe p-layer. Thus, a small charge pulse is produced after [4.21],...

Parker [55] studied the IN properties of MEH-PPV sandwiched between various low-and high work-function materials. He proposed a model for such photodiodes, where the charge carriers are transported in a rigid band model. Electrons and holes can tunnel into or leave the polymer when the applied field tilts the polymer bands so that the tunnel barriers can be overcome. It must be noted that a rigid band model is only appropriate for very low intrinsic carrier concentrations in MEH-PPV. Capacitance-voltage measurements for these devices indicated an upper limit for the dark carrier concentration of 1014 cm"3. Further measurements of the built in fields of MEH-PPV sandwiched between metal electrodes are in agreement with the results found by Parker. Electro absorption measurements [56, 57] showed that various metals did not introduce interface states in the single-particle gap of the polymer that pins the Schottky contact. Of course this does not imply that the metal and the polymer do not interact [58, 59] but these interactions do not pin the Schottky barrier. 

That the Am term must, in fact, be present can also be inferred from the requirement that >pin(x) be the asymptotic field to which asymptotic condition in Section 11.5 of the present chapter. 

A review of the vast amt of work performed in the field of percussion primers reveals what is essentially an empirical approach to the development of both primer designs and priming mixts. It is recognized that a percussion primer must perform two vital functions (1) it must fire , ignite , or otherwise function when provided with the proper mechanical stimulus — a firing pin (with optimum contour to its striking end) and (2) it must perform its other function by which the flame , fire , or output will ignite the proplnt properly so as to provide the projectile with the specified velocity and within... 

Fig. 3.15 Left External view of the MIMOS II sensor head (SH) with pyramid structure and contact ring assembly In front of the Instrument detector system. The diameter of the one Euro coin is 23 mm the outer diameter of the contact-ring is 30 mm, the inner diameter is 16 mm defining the field of view of the Instrument. Right. Mimos II SH (without contact plate assembly) with dust cover taken off to show the SH Interior. At the front, the end of the cylindrical collimator (with 4.5 mm diameter bore hole) Is surrounded by the four SI-PIN detectors that detect the radiation re-emltted by the sample. The metal case of the upper detector is opened to show its associated electronics. The electronics for all four detectors Is the same. The Mossbauer drive is inside (in the center) of this arrangement (see also Fig. 3.16), and the reference channel is located on the back side In the metal box shown In the photograph...

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