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Project

1-Wire Weather Station

The weather station in this project is quite basic, measuring only temperature, pressure, and humidity, but it may be easily expanded to measure other weather components, such as wind speed and rainfall. The design is based on using a series of…

Project

3x3x3 LED Cube

LEDs (light-emitting diodes) are rectifying semiconductor devices that convert electrical energy into electromagnetic radiation. You can use these devices to create a 3-dimensional light display. LED cubes require some care and good soldering skills…

Project

Chatbot, an Artificially Intelligent Microcontroller

The term "Chatbot" is used for a computer or computer program that is made to emulate some form of human intelligence through conversation. In this project, you will learn how easy it is to make a specific microcontroller—an Arduino™ Uno—seem as…

Project

Text-Controlled RGB LED

A red, green, and blue (RGB) light-emitting diode (LED) is a useful electronic component that can produce visible light in a variety of colors. This is done by varying the intensity of the light output of the three different color LED elements (red,…

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from article Acari

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Parasitiformes body plan. Lateral view of a predatory adult female Mesostigmata showing major body regions and important structures. Scale bar = 0.1 mm (0.004 in.). (Scanning electron micrograph by D. E. Walter)

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from article Acari

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Acariformes body plan. (a) Adult female Oribatida (Sarcoptiformes) in lateral view showing major body regions and important structures. (b) Hexapod larva (Trombidiformes): dorsal view of a chigger, a parasite of vertebrates. (c) Octopod deutonymph…

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from article Anthrax

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A color-enhanced scanning electron micrograph showing splenic tissue from a monkey with inhalation anthrax. Rod-shaped bacilli of Bacillus anthracis (yellow) and an erythrocyte (red) are shown. (Credit: Arthur Friedlander/National Institute of…

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from article Anthrax

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Micrograph (stained with hematoxylin and eosin) showing submucosal hemorrhage in the small intestine of a person fatally affected by gastrointestinal anthrax. (Credit: Marshal Fox/Centers for Disease Control and Prevention)

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from article Haplosporida

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Spore of Urosporidium fuliginosum.

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from article Haplosporida

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Stages in the development of Icthyosporidium giganteum.

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from article Transmission lines

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Two common transmission lines for communication. (a) Coaxial cable. (b) Strip line.

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from article Transmission lines

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Equivalent circuit that represents three sections of a lossless transmission line. Each section is of length Δz, and has an inductor (L) and capacitor (C). Voltages (V ) and currents (I ), and their differences (ΔV and ΔI ) between successive…

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from article Transmission lines

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Signal detection on an oscilloscope. (a) Oscilloscope pictures of voltage pulses at three locations, z1, z2, and z3, on a transmission line, successively more distant from the signal generator. (b) Oscilloscope pictures of a periodic voltage sine…

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from article Transmission lines

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Transmission line with characteristic impedance Zc, terminated in a load impedance ZL. A change of coordinate system (from z to ζ) is indicated.

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from article Transmission lines

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Envelope of the voltage standing wave consisting of a wave propagating from z = −∞ and being reflected at z = 0. The wavelength, λ, and the maximum and minimum voltages, Vmax and Vmin, are indicated.

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from article Transmission lines

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Two waveguides, with conventional coordinates. (a) Rectangular waveguide. (b) Cylindrical waveguide.

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from article Transmission lines

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Dispersion curve for a rectangular waveguide of width a, showing relationship between the propagation constant, β, and the angular frequency, ω. Here, n specifies the mode of propagation, and c is the speed of light.

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from article Transmission lines

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Equivalent circuit of a power transmission line. The single-phase circuit is used to represent balanced three-phase lines. Here, R and X are the resistance and reactance (at the operational frequency), and C is the capacitance of the entire…

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from article Urodela

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A typical member of the order Urodela: the longtail salamander (Eurycea longicauda). (Photo by Ryan Hagerty, U.S. Fish and Wildlife Service)

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from article Urodela

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World distribution of salamanders (order Urodela), indicated by areas of shaded blue color.

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from article Urodela

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California tiger salamander (Ambystoma californiense). (Photo by John Cleckler, U.S. Fish and Wildlife Service)

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from article Urodela

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The two-toed amphiuma salamander (Amphiuma means). (Photo courtesy of the Southeast Ecological Center, U.S. Geological Survey, Gainesville, FL)

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from article Urodela

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The northern red salamander (Pseudotriton ruber ruber). (Photo by Alicia Lafever, U.S. National Park Service)

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from article Chamois

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Alpine chamois (Rupicapra rupicapra). (Photograph courtesy of Brent Huffman/Ultimate Ungulate Images)

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from article Chicxulub impact crater

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Bouguer gravity anomaly map over the Chicxulub impact crater. The coastline is designated by a thin white line, cenotes (natural pits) and sinkholes are designated by black dots, and the city of Mérida and the town of Chicxulub Puerto are designated…

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