Windows seats

Small ultrasonic motors such as the rotary actuator shown in Figure 10 have also been made and can be used for automobile windows, seats, and windshield wipers. Many small industrial motors could make use of the high torque, low speed, and precise stepping character of these actuators. 

In the draped shadows of the window seating, an older Caucasian man sat with a younger Asian man, talking over two cocktails in the low, unhurried tone of a transaction. 

Your brother Master Edward was just the same, said Mai, loosening her wrappings and casting her cloak on the window-seat. A pity she ll not be Admiral of the Fleet like her uncle, for I warrant she d do well... She sat down beside me. And how keep you, madam ... 

The Problem What is the probability that you ll get a window seat if there are 40 rows with 7 seats in a row ... 

When counting the number of seats for this problem, you have to be careful not to count the same seats more than once. Some of the seats in the last four rows are also window seats. 

Applying this rule to the seats on the plane, there are 4 x 7 = 28 seats in the last four rows and 2 x 40 = 80 window seats. The last four rows have 4x2 = 8 window seats. So the number of seats you want is 28 + 80 - 8 = 100 seats that are either in the last four rows or a window seat (or both) The probability that you ll get one of those seats is found with... 

The Doctor stopped alone at the door and rapped lightly. He had only a moment s wait before she opened the door. A fur-lined pelisse draped over her dress, she beckoned him in with her eyes more than the simple gesture of her hand. The Doctor entered and she withdrew to the window seat. A fur hat and gloves rested beside her. 

After it was done, I put the flower on the window seat, where it had an untouchable sheen in its glass prison, like a pebble in water. I was guilty of neglect. As I worked, I should have willed myself inside the rose to blend my spirit with its sap, but one look at that stranger had blown away my concentration. I was listening for his departure. I had to catch another glimpse of him before he left. 

The laboratory was cold and dark. It never used to be, but now it was. I went to the window and flung back the shutters one after another until the room was revealed in all its complicated vastness. Then I sank down on the window seat. Everything was wrong. The laboratory had been the hub of my universe, its wheels turned by fire and water, the instruction of our notebooks, the recording of our processes. I had indexed and labeled its contents myself because my father, fanatical about order and economy, depended on being able to put his hand on a book, a substance, a crucible the instant he needed it. And every instrument had to be maintained to a perfect level of utility scales balanced, chisels polished, irons scrubbed clear of rust, chemicals redated and replenished. Even while the hedges on our land were broken and our roses mildewed, our laboratory had remained airy, well oiled, constant. But now the room was furred by a kind of violent neglect. 

Thus, for a ratio for d/D of 1 2 and for an inner pressure of 1 GPa, the pressure at the window-seat interface is 1.33 GPa and the overpressure which opposes the leak is 333 MPa. In the same way as the Bridgman seals described in Section 1, increasing the pressure will tend to reduce leaks. Another advantage of the Poulter geometry is that the window material is subjected to the hydrostatic pressure it is meant to contain. This enhances its mechanical properties since the elastic coefficients of solids usually increase under high pressures. 

The window seat material is subjected to an overpressure of Pj (see 3.5.10). Obviously this pressure should not exceed the compressive strength of the window-seat material. Under high-overpressure conditions (Pj > 1800 MPa) a hard-steel or tungsten-carbide insert should be shrunk into the high-pressure optical plug for proper seating of the window. 

The window seating is shown schematically in Fig. 3.21. The initial seal on the window is made under moderate compression by a metallic cap, which simply keeps the window in place at low pressures. 

The inner edge of the window seat must be rounded off to avoid any knife-edge effects on the window when it starts to bend in under pressure. The practical radius for sapphire windows with an unsupported-area diameter of 6 mm is 0.3 0.1 mm. 

The outer diameter of the window seat should be matched to the diameter of the window itself, and it must not be larger. At the highest pressures, the force acting on the window may be sufficient to imprint it slightly into the seat due to the bending in (concavity) under load of a Bridgman-type plug such as that shown in Fig. 3.22. This will cause failure of the window on the downstroke. 

Fig. 3.21 A Poulter-type window on an unsupported-area Bridgman optical plug, used for window testing (a) window, (b) flat window seat, (c) hard-steel plug, (f) washer packing, (g and h) bevels on the outside of the plug and the window, (i) a bevel on the inside diameter of plug and, (j) a retaining brass cap d and D are the inner and outer diameters of the window seat e is the thickness of the window (from reference 16).

Fig. 3.26 A window seating with a square ring seal on the plug . (This and Figs. 3.27, 3.28 reprinted with permission from Rev. Phys. Appl., 5, 333, (1970).)...

Fig. 3.27 A window seating with a Bridgman plug (a) high-pressure medium, (b) a sapphire window, (c) a hard-steel plug (52 HRC), (d) washer packing, (e) a retaining breech. The dimensions are in millimetres .

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