Tapered profile

Expander-compressor shafts are preferably designed to operate below the first lateral critical speed and torsional resonance. A flame-plated band of aluminum alloy or similarly suitable material is generally applied to the shaft in the area sensed by the vibration probes to preclude erroneous electrical runout readings. This technique has been used on hundreds of expanders, steam turbines, and other turbomachines with complete success. Unless integral with the shaft, expander wheels (disks) are often attached to the shaft on a special tapered profile, with dowel-type keys and keyways. The latter design attempts to avoid the stress concentrations occasionally associated with splines and conventional keyways. It also reduces the cost of manufacture. When used, wheels are sometimes secured to the tapered ends of the shaft by a common center stretch rod which is pre-stressed during assembly. This results in a constant preload on each wheel to ensure proper contact between wheels and shaft at the anticipated extremes of temperature and speed. 

On the other hand, if uniform step coverage is desired, a tapered profile like that in Figure 14 is essential since highly anisotropic profiles... 

Velocity varies across the vessel due to viscous and inertial effects as mentioned earher. The velocities in Figure 56.3 were measured at one point in the artery. Velocity profiles are complex because the flow is pulsatile and vessels are elastic, curved, and tapered. Profiles measured in the thoracic aorta of a dog at normal arterial pressure and cardiac output are shown in Figure 56.4. Backflow occurs during diastole, and profiles are flattened even during peak systohc flow. The shape of the profiles varies considerably with mean aortic pressure and cardiac output [Ling et al., 1973]. 

Straight tapered profile to small ball-shaped tip... 

At present there are three types of profile dies used. orifice dies, multistage dies, and tapered profile dies. An example of an orifice die is shown in Figure 7.42. Basically the orifice die consists of a die base and a die plate in which the profile is formed. These dies are used for the extrusion of inexpensive profiles where dimensional accuracy is not necessary. Because of the abrupt change in cross-sectional area, there is usually a buildup of stagnant material behind the die plate and high extrusion rates are not possible. These dies are not commonly used for most thermoplastics but are restricted primarily to PVC and mbber. 

When significant continuous loads have to be taken on a thrust washer, it is necessary to machine into the bearing surface a profile to generate a fluid film. This profile can be either a tapered wedge or occasionally a small step. 

The crown profile dictates the type of formation for which the bit is best suited. They include the round, parabolic, tapered and flat crown used in hard to extremely hard formations, medium to hard formations, soft formations and for fracturing formations or sidetracks and for kick-offs, respectively. 

Figure 4-164 shows a steel body core bit with a long-taper, stepped profile fitted with impregnated natural diamond blocks as the primary cutting elements. The bit has no inner cone. Since there is no specific code for the natural diamond/steel body combination, the letter O (other) is used as the cutter type/ body material code. The profile code 3 is used to describe the long outer taper with little or no inner cone depth. The hydraulic design code 5 indicates a fixed... 

The location of the primary dull characteristic is described in the fourth space. There are six choices cone, nose, taper, shoulder, gauge, and all areas. Figure 4-167 shows four possible fixed cutter bit profiles with the different areas labeled. It is recognized that there are profiles for which the exact boundaries between areas are debatable and for which certain areas may not even exist. Notice that in the bottom profile there is no taper area shown. However, using Figure 4-167 as a guide, it should be possible to clearly define the different areas on most profiles. 

In the design of systems it is most important to eliminate as much turbulence as possible, and to achieve this the fans should be mounted some distance away from bends (at least one and a half duct diameters). Junctions between pipes and connectors should present a smooth internal profile and inlets to systems must be tapered and not plain. Outlet grills should be of larger diameter than the duct and have aerodynamically smooth profiles where possible. 

Two-way The two-way clutch uses square or tapered teeth to provide positive mating between its drive and driven halves. This tooth profile provides positive power transmission in both directions of rotation. 

The waU thickness of the taper produced by drawing down the larger tube can have an effect on the profile of the finished joint (Figure 23). If this taper has a wall thickness about the same as the unworked tube it will tend to retain its profile in working, but if it is thin-walled the joint will tend to have a rounded profile. This provides a method of controlling the type of joint produced. A rounded profile can be produced by starting with a uniformly thick rounded end. 

Early investigators assumed that this so-called diffusion layer was stagnant (Nernst-Whitman model), and that the concentration profile of the reacting ion was linear, with the film thickness <5N chosen to give the actual concentration gradient at the electrode. In reality, however, the thin diffusion layer is not stagnant, and the fictitious t5N is always smaller than the real mass-transfer boundary-layer thickness (Fig. 2). However, since the actual concentration profile tapers off gradually to the bulk value of the concentration, the well-defined Nernst diffusion layer thickness has retained a certain convenience in practical calculations. 

Fig. 32 Changes in the lamella profiles viewed along the x-axis, during melting at 380 K a at 0.0 ns, b at 0.128 ns, c at 0.64 ns. We can see that the tapered growth fronts retreat at 380 K maintaining the tapered shape at the edges...

In their study of branched PSA, Maniar et al. (1990) found that the molecular architecture of branched polymers affects the release kinetics in a variety of ways. They found that the branched polymers degraded faster than linear PSA of comparable molecular weight (Maniar et al., 1990). They also noted that drug (morphine) release profiles were more characteristic of bulk erosion than surface erosion An initial lag time during which very little drug was released was associated with the time required for water to swell the polymer. This was followed by a period of relatively fast release, which tapered off as the device disintegrated. The polymer matrix lost its mechanical integrity before the release experiment was complete (Maniar et al., 1990). Despite the increase... 

Figure 5.21 a shows an SEM micrograph (in cross section) of a feature ablated in doped PTFE, specifically 0.5% polyimide, at 12 J/cm2. The ablated feature is well defined and exhibits a smooth wall profile, typical of all blends having more than 0.1% (wt/wt) polyimide. The sidewall profiles of the less heavily doped blends are extremely vertical, having less taper than typically observed for more heavily doped PTFE films, e.g., 1.0 and 5.0% (Figures 5.21b and 5.21c, respectively) or Upilex-S polyimide, (Figure 5.21d). Ablation rates for a variety of PI-PTFE blends [0.2-5% polyimide (wt/wt) and neat polyimide] at 248 nm and 308 nm are shown in Figures 5.22 and 5.23, respectively.78...

Figure 14. Etch profiles for isotropic, tapered, and anisotropic etching of a film. Sq, Wq and Sf, Wf represent mask dimensions before etching and feature dimensions after etching, respectively. The degree of undercutting (dfj) and wall taper (6) are indicated for etching to a depth (dy) that exposes just the initial mask dimensions in the substrate. (Reproduced with permission from Ref. 11J...

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