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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

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

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 Haplosporida

Spore of Urosporidium fuliginosum.

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from article Haplosporida

Stages in the development of Icthyosporidium giganteum.

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from article Transmission lines

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

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from article Transmission lines

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

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

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

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

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

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from article Transmission lines

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

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

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

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

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from article Urodela

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

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from article Urodela

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

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

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from article Chamois

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

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from article Amniota

Basic types of vertebrate eggs.

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from article Amniota

Embryo developing in amniote eggs.

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from article Mecoptera

Male scorpion fly (Panorpa), order Mecoptera.

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from article Crosstalk

Crosstalk in a space-division system. Z1, Z2, Z3, and Z4 designate impedances.

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from article Computer-aided circuit design

Four phases in creating a microelectronic chip. (a) Design. (b) Fabrication. (c) Testing. (d) Packaging. (After G. De Micheli, Synthesis and Optimization of Digital Circuits, McGraw-Hill, 1994)

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from article Computer-aided circuit design

Three abstraction levels of a circuit representation. (a) Architectural level. (b) Logic level. (c) Geometrical level. (After G. De Micheli, Synthesis and Optimization of Digital Circuits, McGraw-Hill, 1994)

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from article Saccopharyngiformes

Pelican or gulper eel (Eurypharynx pelecanoides), a member of the order Saccopharyngiformes. [Photo by Alexei Orlov, Russian Federal Research Institute of Fisheries and Oceanography (VNIRO), Moscow, Russia]

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from article Computer security

Applications such as power generation, stock trading, airplane navigation, and medical care have become so dependent on computing that loss of availability becomes a serious threat to life or society. Even on a less dramatic level, people have…

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from article Computer security

Smartphone with fingerprint identification. (Credit: Anatoliy Babiy/Getty Images)

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from article Programmable controllers

Functional architecture of a typical high-performance single-chip microcontroller used for control and signal processing. (National Semiconductor Corp.)

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from article Llama

The llama (Lama glama) of South America.

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from article Platypus

Platypus, a primitive aquatic mammal. (Photograph by Paddy Ryan/Ryan Photographic)

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from article Acanthometrida

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from article Sarcodina

Some shelled Lobosia. (a) Arcella, seen from above; (b) sporulating into numerous ameboid young; (c) in binary fission, with the two nuclei in mitosis with polar caps; part of the cytoplasm exudes from the pylome and secretes a new shell. (d)…

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from article Sarcodina

Heliozoia. (a) Actinosphaerium. (b) Actinophrys. (c) Axopodium of Actinosphaerium, highly magnified. (d) Heterophrys. (e) Acanthocystis. (After L. H. Hyman, The Invertebrates, vol. 1, McGraw-Hill, 1940)

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from article Paleocopa

Paleocopa. (a) Ogmoopsis nodulifera, left valve; from the Ordovician of Sweden. (b) Eurychilina subradiata, right valve showing wide complete frill; Ordovician of Minnesota. (c) Sulcicuneus porrectinatium, male and female carapaces; Devonian of…

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from article Podocopida

Candona suburbana, an ostracod of the Cypridoidea. Animals with right valves removed. (a) Female; note dimorphic differences in carapace outline and first leg. (b) Male with hemipenis rotated, folded, and retracted; part of the body wall is removed…

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from article Podocopida

Limnocythere sanctipatricii, a podocopid ostracod of the Cytheroidea. (a) Male with left valve removed; the paired hemipenes occupy much of the space at the rear of the carapace. (b) Male left “brush-shaped organ,” an unusual structure found only in…

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from article Podocopida

Darwinula stevensoni, a podocopid ostracod of the Darwinuloidea. In this parthenogenetic species, eggs and young are protected in a brood space behind the body. (After R. C. Moore, ed., Treatise on Invertebrate Paleontology, pt. Q, 1961)

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from article Social mammals

Meerkats (Suricata suricatta) are notable social mammals. Here, they are looking for danger outside of their den. (Credit: Alta Oosthuizen/Shutterstock)

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from article Social mammals

An adult female African lion (Panthera leo) nurses four cubs. The early ingestive behavior (nursing) of mammals has a high degree of social significance. (Credit: Glow Images)

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from article Social mammals

Mexican spider monkeys (Ateles geoffroyi vellerosus) are primates that display many examples of social behavior and organization. (Credit: Oksana Kunka/123RF)

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from article Concentricycloidea

Aboral surface of a sea daisy.

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from article Concentricycloidea

Underside of a sea daisy, which is occupied by a large oral opening.

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from article Ultrawideband (UWB) systems

Relationships between various UWB systems.

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from article Ultrawideband (UWB) systems

Frequency-modulated continuous-wave (FMCW) swept-frequency signaling. (a) Plot of the amplitude of the continuous wave against time, showing it gradually changing frequency. (b) Frequency-versus-time plot.

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from article Ultrawideband (UWB) systems

Spectrum of WiMedia UWB, which uses 14 RF carriers coordinated for maximum data throughput.

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from article Ultrawideband (UWB) systems

Plots of a pulsed radio or pulsed radar transmission. (a) Time plot. (b) Frequency plot.

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from article Ultrawideband (UWB) systems

Coherent pulse integration values of (a) 16 through (b) 512 pulses per symbol increase signal-to-noise ratio with limited transmit power.

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from article Ultrawideband (UWB) systems

Time difference of arrival (TDOA) tracking, which combines multiple time-of-arrival (TOA) measurements to localize pulse origin.

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from article Ultrawideband (UWB) systems

Timing diagram of a two-way time-of-flight (TW TOF) ranging conversation.

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from article Directional coupler

Four-port directional waveguide coupler.

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from article Directional coupler

Two-hole directional coupler.

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from article Directional coupler

Single-mode fiber-optic directional coupler.

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from article Calculators

Electromechanical calculator manufactured in the 1960s. (Hewlett-Packard)

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from article Calculators

Modern programmable electronic calculator. (a) Front of calculator, featuring liquid-crystal display, qwerty-style keyboard, cursor key, and function keys. The display is composed of 128 rows of 240 pixels each, and here shows a three-dimensional…

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from article Communications satellite

Artist impression of TDRS-L, the 11th member of NASA's Tracking and Data Relay Satellite System, orbiting Earth at 36,000 km (22,300 mi). TDRS-L sends signals, information, and commands from ground controllers to the International Space Station and…

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from article Communications satellite

Communications to and from a satellite.

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from article Communications satellite

Typical communications satellite. TWTA = traveling-wave–tube amplifier. (Credit: Space Systems/Loral)

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from article Communications satellite

Orbit periods of circular orbits.

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from article Vampyromorpha

Vampyroteuthis infernalis (vampire squid) living in the oxygen-minimum zone of Monterey Bay, California, at depths of 600–900 m (1970–2950 ft). (Photo courtesy of Kim Reisenbichler, Monterey Bay Aquarium Research Institute, Moss Landing, CA)

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from article Vampyromorpha

Vampyroteuthis infernalis (vampire squid) showing sensory filaments and photophores (light organs).

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from article Civet

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from article Patellogastropoda

Whitecap limpet (Acmaea mitra). (Photo by Douglas Eernisse)

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from article Patellogastropoda

Ribbed Mediterranean limpet (Patella ferruginea). (Photo by Georgina Rivera Ingraham)

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from article Patellogastropoda

Radula of the patellogastropod Notoacmea scapha.

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from article Bicosoecida

A bicosoecid, Codomonas annulata.

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from article Rhizocephala

Loxothylacus texanus (arrow) attached to the abdomen of the blue crab (Callinectes sapidus). (After E. G. Reinhard, Parasitic castration of Callinectes, Exp. Parasitol., 5:79–107, 1956)

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from article Algorithm

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from article Algorithm

An array of n elements.

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from article Algorithm

Inserting and deleting an element from a stack.

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from article Algorithm

Inserting and removing an element from a queue.

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from article Algorithm

An example of a tree.

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from article Algorithm

A graph with four vertices and five edges.

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from article Echiura

Echiuran anatomy. (a) External anatomy, ventral view. (b) Internal anatomy, dorsal view. A, anus; AV, anal vesicles; G, gut (middle section removed for clarity); M, mouth; N, nephridia (egg and sperm storage organs); S, setae; VNC, ventral nerve…

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from article Schizomida

Schizomus sawadai. (After K. Sekiguchi and T. Yamasaki, A redescription of “Trithyreus sawadi” (Uropygi: Schizomidae) from the Bonin Islands, Acta Arachnol., 24(2):73–81, 1972)

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from article Data structure

Linear array of integers.

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from article Data structure

A stack, a linear list in which elements are inserted or deleted only at one end.

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from article Data structure

A queue, a linear list that permits insertion at one end and deletion at the other.

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from article Data structure

Singly linked list or one-way chain.

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from article Data structure

Diagram representing a directed graph.

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from article Data structure

Example of a tree.

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from article Data structure

Linked storage representation for a binary tree.

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from article Notomyotida

Some diagnostic features of representative Notomyotida. (a) Paxillae and one pectinate pedicellariae of Cheiraster richardsoni. (b) Benthopecten pentacanthus.

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from article Jerboa

Jerboa. (Photograph by Pekka Fågel)

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from article Ratites

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from article Ratites

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from article Choanoflagellida

A linear colony of the choanoflagellate, Desmarella moniliformis.

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from article Machine learning

Machine-learning algorithms will help self-driving cars reliably handle unexpected situations they encounter on the road. (Credit: Karsten Neglia/Shutterstock)

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from article Trematoda

Phylogeny of the Neodermata. Note that the monophyly of the Neodermata has been confirmed by many morphological and DNA studies. The phylogeny of the various neodermatan subgroups may have to be revised on the basis of studies using mitochondrial…

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from article Trematoda

Furcocercaria of Schistosoma. Note the forked tail.

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from article Trematoda

Eggs of Schistosoma species. Note the differently developed spine and egg shape in the various species shown.

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from article Trematoda

Paragonimus species. Note the spinose tegument. Worms are about 1.5 cm (0.6 in.) in length.

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from article Acantharea

Representatives of the Acantharea; Acanthometra pellucida, (a) showing axial rods extending through the central capsule, and myonemes (myophrisks) extending from the rods to the sheath; (b) contracted myophrisks with expanded sheath; and (c) relaxed…

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from article Ophiurida

Brittle star, Ophiolepis impressa (order Ophiurida, family Ophiolepididae), found on coral reefs in the tropical western Atlantic. (After G. Hendler et al., Sea Stars, Sea Urchins and Allies: Echinoderms of Florida and the Caribbean, Smithsonian…

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from article Neritimorpha

Female Nerita laying egg capsules.

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from article Neritimorpha

Sea grass snail Smaragdia with cryptic green coloration.

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from article Neritimorpha

Red-blooded Phenacolepas limpets.

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