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A 1951 USAF resolution test chart is a microscopic optical resolution test device originally defined by the U.S. Air Force MIL-STD-150A standard of 1951. The design provides numerous small target shapes exhibiting a stepped assortment of precise spatial frequency specimens.
See also: Electronegativities of the elements (data page) There are no reliable sources for Pm, Eu and Yb other than the range of 1.1–1.2; see Pauling, Linus (1960).
The Portland Water Bureau is the municipal water department for the city of Portland in the U.S. state of Oregon.The bureau manages a water supply that comes mainly from the Bull Run River in the foothills of the Cascade Range east of the city and secondarily from the Columbia South Shore Well Field near the Columbia River.
A printed circuit board (PCB), also called printed wiring board (PWB), is a laminated sandwich structure of conductive and insulating layers, each with a pattern of traces, planes and other features (similar to wires on a flat surface) etched from one or more sheet layers of copper laminated onto or between sheet layers of a non-conductive ...
An insulation test set; in this pattern, a hand-cranked generator provides the high voltage and the scale is directly calibrated in megohms. Voltage withstand testing is done with a high-voltage source and voltage and current meters. A single instrument called a "pressure test set" or "hipot tester" is often used to perform this test.
The core of a well printed PWB lies in the fill and release of solder paste into the aperture. When the stencil is in contact with the PWB, solder paste is applied over the top surface of the stencil using a squeegee. This causes the aperture to fill with solder paste. The PWB is then lowered from the stencil.
PWB may refer to: Partial Weight-bearing, in which patients are instructed to put only a certain amount of weight on their leg after surgery; Printed wiring board; Psychological well-being; Programmer's Workbench, an early UNIX from Bell Labs, see PWB/UNIX
Printed circuit board with the mark "94V-0" in the bottom-left corner. UL 94, the Standard for Safety of Flammability of Plastic Materials for Parts in Devices and Appliances testing, is a plastics flammability standard released by Underwriters Laboratories of the United States. [1]