cutoff operation
21environmental works — ▪ civil engineering Introduction infrastructure that provides cities and towns with water supply, waste disposal, and pollution control services. They include extensive networks of reservoirs, pipelines, treatment systems, pumping stations …
22List of vacuum tubes — This is a list of vacuum tubes or thermionic valves. Before the advent of semiconductor devices, hundreds of tube types were used in consumer and industrial electronics; today only a few types are still used in specialized applications. Contents… …
23Light pollution — This article is about light pollution in the visible spectrum. For information on pollution in the radio spectrum, see radio spectrum pollution. This time exposure photo of New York City at night shows skyglow, one form of light pollution …
24Old Main Line Subdivision — Ellicott City Station, built 1830, is the oldest surviving passenger station in the United States. Photo taken in 1970, looking south towards Baltimore …
25Theories of general anaesthetic action — Structures of general anaesthetics widely used in medicine. A general anaesthetic (or anesthetic) is a drug that brings about a reversible loss of consciousness. These drugs are generally administered by an anaesthetist/anaesthesiologist in order …
26Waveguide — This page is about waveguides in the most general sense. For ordinary metal pipe waveguides, Waveguide (electromagnetism). For optical waveguides, see Waveguide (optics). A section of flexible waveguide with a pressurizable flange …
27Vacuum tube — This article is about the electronic device. For experiments in an evacuated pipe, see free fall. For the transport system, see pneumatic tube. Modern vacuum tubes, mostly miniature style In electronics, a vacuum tube, electron tube (in North… …
28Low-pass filter — A low pass filter is a filter that passes low frequency signals but attenuates (reduces the amplitude of) signals with frequencies higher than the cutoff frequency. The actual amount of attenuation for each frequency varies from filter to filter …
29Delaware, Lackawanna and Western Railroad — Reporting mark DLW Locale Pennsylvania, New York and New Jersey Dates of operation 1851–1960 …
30History of street lighting in the United States — The use of street lighting was first recorded in the Arab Empire from the 9th 10th centuries, [Fielding H. Garrison, History of Medicine :quote| The Saracens themselves were the originators not only of algebra, chemistry, and geology, but of many …
