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Project

3D Floor Plan

Floor plans show walls, windows, doors, and other features of a room or building. Architects and engineers use them to study spatial relationships and describe their designs. Typically, floor plans are rendered as two-dimensional drawings.In this…

Project

3D Skull Candy Mold

Whether preparing for Halloween or just a regular day, you can make skull-shaped edibles from this project's 3D candy mold. Like many molds, this one is a hollow container into which you can pour water or hot liquids, such as gelatin, chocolate, or…

Project

3D Spur Gear

A spur gear is a common toothed wheel that works with other wheels in a set to adjust the speed, power, or direction of a complex machine. It's found in many everyday devices, such as electric screwdrivers, washing machines, and mechanical clocks…

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3D Terrain Map

Terrain maps are physical models that give you an at-a-glance overview of landforms. Architects, builders, and engineers often use these types of maps to provide context to proposed building designs. In this project, you'll create a layered…

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…

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Arduino Oscilloscope

An oscilloscope is a device that allows you to see an electronic signal so that it appears as a waveform. Traditional oscilloscopes work by amplifying a signal to control the position of a dot on the y-axis (vertical axis) of a cathode-ray tube…

Project

Heart-Rate Monitor

This project uses a sensitive light-detecting resistor to detect small changes in the light beaming through your finger as your blood pumps through tiny arteries in the finger. This device is not the same as the heart-rate monitors typically used in…

Project

Jumbo Foam Glider

This project takes you through the steps to build, launch, and fly a foam glider in sustained and controlled flight. Control in flight is achieved by modifying the wind the glider flies through with a large cardboard sheet (paddle). If this is your…

Project

Levitation Machine

This project allows you to use electromagnetic levitation to suspend a globe of the world above a surface. The "globe" is actually a table tennis ball painted to look like a globe. Keeping it in place requires careful control of electrical current…

Project

Light and Temperature Logger

Environmental research often involves the use of data loggers to record data at regular intervals over a period of time. Most data loggers are based on digital processors, and can be fairly expensive, but you can build your own. This project uses a…

Project

Pulse Generator Circuit

A pulse generator circuit is an important building block for many electronic projects, such as the heart of a digital clock. Its purpose is basically to switch an output on and off for as long as the circuit is activated. Sometimes, these circuits…

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,…

Project

Tumblewing Walkalong Glider

This project takes you through the steps to build, launch,and fly a paper airplane (glider) in sustained and controlled flight. Control in flight is achieved by modifying the wind the glider flies through with a large cardboard sheet or foam board…

Project

Ultralight Foam Glider

This project takes you through the steps to build, launch, and fly an ultralight foam glider in sustained and controlled flight. Controlled flight is achieved by modifying the wind the glider flies through with a large cardboard sheet, or paddle.The…

Project

Wind Lantern

In this project, you will build a small, vertical-axis wind turbine, or VAWT for short. VAWTs are not as efficient as their horizontal-axis cousins, but they are better suited to urban environments where wind can come from different…

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from article Electret

Schematic cross sections of electrets. (a) Solid electret disk metallized on one side with real charges (surface and space charges) and dipolar charges. (b) Cellular electret metallized on both sides with charges of opposite polarities on the upper…

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from article Chemistry

Periodic table. (Jaap Hart/Getty Images)

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from article Flat-panel display device

Field-emission display, an example of a matrix-addressed display. Each pixel is addressed in an X-Y matrix. In the case of a color display, each pixel is subdivided into a red, a blue, and a green subpixel.

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from article Parasympathetic nervous system

Overview of parasympathetic pathways of the human autonomic nervous system. Preganglionic axons from the brain and spinal cord innervate the viscera in the head, neck, and trunk. (Copyright © McGraw Hill)

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from article Fertilization (animal)

Photomicrograph (tinted green) of mouse sperm bound to the zona pellucida of an unfertilized egg under laboratory conditions (in vitro). (Credit: K. O. Kalthoff)

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from article Fertilization (animal)

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from article Chemical senses

The sense of smell (olfaction) is a key chemical sense in vertebrates. (Left) Taste buds of the oral cavity, especially the tongue, are composed of modified epithelial cells responsive to chemicals in solution. (Right) Bitter, sour, salty, and sweet…

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from article Sewage solid

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from article Sewage solid

Time required for 90% digestion of sewage sludge at different temperatures. (After K. Imhoff and G.M. Fair, Sewage Treatment, John Wiley & Sons, 1940, reprint 1946)

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from article Mercury (element)

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from article Mercury (element)

Mercury droplets exhibiting non-wetting of the surface. (Credit: A. Cerar/Getty Images)

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from article Mercury (element)

Tooth with a silver-amalgam filling. (Credit: Szasz-Fabian Jozsef/Shutterstock.com)

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from article Spring (machines)

Flat or leaf spring responds to perpendicular forces in either direction.

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from article Spring (machines)

Helical spring. (a) Wound tight to extend under axial tension. (b) Wound loose to contract under axial compression.

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from article Spring (machines)

Spiral spring is unique in responding to torsional or translational forces.

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from article Spring (machines)

Disk spring. (a) Single tapered disk; (b) multiple disk; (c) Belleville spring; (d) slotted curved washer; (e) finger washer; (f) wave spring washer.

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from article Spring (machines)

Correction factor for curvature and shear. (After A. M. Wahl, Mechanical Springs, Penton, 1944)

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from article Pigmentation

Colorful flower of Mirabilis jalapa. The colors of the flowers of this plant can vary as a result of different plant pigments. (Credit: F. D. Richards)

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from article Pigmentation

Zebrafish are often studied as model organisms for research dealing with skin pigmentation. (Credit: Lynn Ketchum/Oregon State University)

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from article Neurohypophysis hormone

Structure of neurohypophysial hormones. Each neurohypophysial hormone is made up of nine amino acid residues with two half cysteines joined by a disulfide bridge to form a ring structure. Vasotocin is found in fishes and fetal pituitaries, while…

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from article Cantilever

Cast-in-place segmental balanced cantilever bridge construction. (Credit: U.S. Department of Transportation, Federal Highway Administration)

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from article Cantilever

Crane illustrating the structural principle of a cantilever: (a) load only, (b) counterweight only, (c) balanced condition. (Credit: Thornton Tomasetti)

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from article Cantilever

The Comcast Center, Philadelphia, Pennsylvania, with an architectural height of 975 ft (297 m) and 57 floors above ground. (Credit: Ken Murphy, Thornton Tomasetti)

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from article Cantilever

View from the top of the Grand Canyon Skywalk. (Credit: Grand Canyon Skywalk)

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from article Peroxisome

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from article Bipolar disorder

Prevalence of bipolar disorder in adults. The bar graph shows the percent of the U.S. adult population affected by bipolar disorder as it relates to age. (Credit: National Institute of Mental Health)

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from article Enzyme inhibition

Enzyme inhibition often works by preventing a substrate from attaching to an active enzyme. In this example, E1 is one of three sequential enzymes that will convert a substrate (S) into a product (P). However, the product that is created can then…

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from article Enzyme inhibition

Two types of reversible enzyme inhibition. (Left) In competitive inhibition, the inhibitor interferes with the active site of the enzyme, so the substrate is unable to bind to it. (Right) In noncompetitive inhibition, the inhibitor changes the…

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from article Organic conductor

Structures of organic conductors. (a) Electron donors. (b) Acceptor molecule (TCNQ) and two monovalent anions. Abbreviations are explained in the text.

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from article Organic conductor

Stacking of charge-transfer compounds. (a) Segregated stacking of TTF-TCNQ-like materials. (b) Typical zigzag stacking of the (TMTSF)2X series.

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from article Organic conductor

Comparison of the range of electrical conductivities of some AsF5-doped conducting polymers with some metals, semiconductors, and nonconducting polymers.

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from article Organic conductor

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from article Adaptive wings

Male and female Cardinal Meadowhawk dragonflies following airborne mating. The male has towed the just-inseminated female to a pond and is dipping her tail in the water so she can deposit her eggs. (Reprinted with permission from the Press Democrat,…

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from article Adaptive wings

Partial representation of the interrelation among flow control goals. (Adapted from M. Gad-el-Hak, Flow Control: Passive, Active and Reactive Flow Management, Cambridge University Press, London, 2000)

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from article Adaptive wings

Large-eddy structures (one type of coherent structure) in a turbulent boundary layer. The side view is visualized using a sheet of laser light and a fluorescent dye. (From M. Gad-el-Hak, R. F. Blackwelder, and J. J. Riley, On the interaction of…

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from article Adaptive wings

Classification of control strategies. (Adapted from M. Gad-el-Hak, Flow Control: Passive, Active and Reactive Flow Management, Cambridge University Press, London, 2000)

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from article Spectrum analyzer

Simplified block diagram of a spectrum analyzer with a tracking generator.

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from article Spectrum analyzer

Typical radio-frequency spectrum analyzer. (IFR Ltd.)

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from article Geometrization theorem

Making a 2-D torus.

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from article Geometrization theorem

Life in Seifert-Weber dodecahedral space. (Courtesy of Geometry Center, University of Minnesota)

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from article Geometrization theorem

Hyperbolic dodecahedron of infinite diameter. The infinite spikes are rounded off “chimneys,” which are here triangular rather than rectangular. (Courtesy of Paul Nylander from http://bugman123.com/)

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from article Geometrization theorem

Neck pinching, resulting in infinite curvature.

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from article Geometrization theorem

Ricci flow with surgery.

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from article Neuroeconomics

Neuroeconomics applies neuroscientific tools and methodologies to investigate the decision making that occurs inside the brain. (Credit: James Steidl/SuperStock)

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from article Doppler VOR

Collocation of Doppler VOR and TACAN beacons installed on 100-foot high (30-m) tower with a counterpoise of 119-ft (36-m) diameter in forest near Frankfurt, Germany. Circular array consists of 39 loop antennas fed by solid-state commutator. Center…

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from article Doppler VOR

Principle of Doppler VOR beacon. Reference signal R and bearing signal V which is generated by dipole d are shown as they would be measured in aircraft to the north, east, south, and west of the beacon. (a) Dipole d at 180°. (b) Dipole d at 270°.…

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from article Doppler VOR

Comparison of radial flight recordings. (a) From VOR installation. (b) From DVOR installation. Both experimental beacons were located at same unfavorable site. Plane is flying constant course at bearing of 133° from beacons at 4000-ft (1.2-km)…

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from article Lysosome-related organelle

Recruitment of cargo molecules into protein-coated (clathrin-coated) vesicles at the trans-Golgi network (TGN) for delivery to incipient lysosomes or lysosome-related organelles. In the TGN, soluble lysosomal or lysosome-related organellar proteins…

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from article Resistance welding

Comparison of basic resistance welding processes. (After B. E. Rossi, Welding Engineering, McGraw-Hill, 1954)

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from article Resistance welding

Three typical resistance welding methods. (a) Spot welding. (b) Seam welding. (c) Projection welding. (After W. H. Kearns, ed., Welding Handbook, 7th ed., vol. 3, American Welding Society, 1976)

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from article Resistance welding

Curves showing difference in current and power waves when circuit is closed nonsynchronously and synchronously. (a) Closure of circuit at incorrect point, with resultant decaying transient. The opening is also nonsynchronous. (b) Synchronous opening…

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from article Matrix theory

Vector rotation that rotates any vector v in the plane counterclockwise through 45° to a new vector Tv.

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from article Radiography

Relation of the penetration characteristics of x-rays to the type and thickness of various materials.

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from article Radiography

Geometry of radiographic image formation. F = size of focal spot of x-ray tube; d = distance from focal spot to specimen (lead plate); t = distance from plate to film; U = unsharpness.

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from article Radiography

Penetrameter. The windows show plan views and cross sections of the penetrameter plates. T is plate thickness; t is object thickness.

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from article Radiography

Chest radiograph of foundry worker made with intense beam from rotating-target x-ray tube, showing nodules in lungs which are caused by silicosis, and shadows of skeleton, heart, and stomach.

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from article Radiography

Thermal neutron radiograph of an investment-cast turbine blade, showing image of residual ceramic. (Industrial Quality, Inc.)

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from article Paleopathology

The fused spine and ribs in a case of ankylosing spondylitis from an adult male human found at a burial site near the Kuskokwim River, Alaska. (Credit: Department of Anthropology, National Museum of Natural History, Smithsonian Institution Catalog…

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from article Paleopathology

Pottery figurine of an achondroplastic dwarf from an archeological site in Tachina, Esmeraldas, Ecuador, dated between 500 BCE and 500 CE. (Credit: Department of Anthropology, National Museum of Natural History, Smithsonian Institution Catalog No.…

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from article Paleopathology

Sword trauma that removed part of the left upper jaw and the right lower jaw so that no remaining teeth were in contact between the jaws. The adult male human survived this injury. The skull is from an archeological burial site near the Stewart…

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from article Paleopathology

Destruction of the lower portion of the fourth lumbar vertebra (arrow), probably caused by tuberculosis, from a young male human skeleton found at the archeological burial site of Bâb edh-Dhrâ in Jordan, dated to approximately 3300 BCE. (Credit:…

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from article Paleopathology

The effect of scurvy on the right side of the cranium of an 11-year-old human child from the archeological site of Pachacamac, Peru. (Credit: Department of Anthropology, National Museum of Natural History, Smithsonian Institution Catalog No. 266599)

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from article Boolean algebra

A portrait of George Boole.

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from article Psychological resilience

Psychological resilience refers to positive adaptation among individuals at risk for maladjustment. There are three classes of protective factors that help people to thrive in the face of significant adversities: support from close family and…

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from article Psychological resilience

The strongest predictor of resilient adaptation is the quality of an individual's close, personal relationships. In general, positive relationships help individuals to combat adversity through collective problem solving and through the sharing of…

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from article Coke

Steps in the production of coke from coal. After the coal has been in the oven for 12–18 h, the doors are removed and a ram mounted on the same machine that operates the leveling bar shoves the coke into a quenching car for cooling. (American Iron…

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from article Calculus of variations

Weierstrass condition. Symbols explained in text.

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from article Calculus of variations

Example of an area-minimizing surface that cannot be written as the graph of a single function. (a) Nonconvex domain C. (b) Minimal graph over C that is not area-minimizing. (c) Second surface over C that has less area. (After F. Morgan, Geometric…

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from article Calculus of variations

Comparison of surfaces. (a) Surface with no handles. (b) Surface with one handle and less area. (c) Surface with two handles and still less area. (d, e, f) These three surfaces are deformed to show that they do have zero, one, and two handles,…

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from article Calculus of variations

Examples of surfaces minimizing the integral of a nonelliptic integrand among all bodies having the same volume (the surface at upper left) and among all surfaces having the same boundary (the saddle-shaped surface). Surfaces were computed as part…

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from article River engineering

Armorflex mats made of concrete blocks connected by nylon cables are used for bank protection. (Armortec Concrete Erosion Control Systems)

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from article River engineering

Channelization of the Santa Gertrudis Creek in California, showing bank protection and grade-control structures traversing the channel bed.

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from article River engineering

River bed scour at a bridge crossing induced by sand mining in the river channel.

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from article River engineering

The Las Vegas Wash (a) in 1975 as a small desert steam. (b) It was destabilized by water released from wastewater treatment plants carrying no sediment, as shown in 1984. (Photos by Pat A. Glancy, U.S. Geological Survey)

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from article River engineering

Grade-control structures installed along the Las Vegas Wash for channel stabilization.

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from article Direct-current generator

Series generator.

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from article Direct-current generator

External characteristics of dc generators.

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from article Direct-current generator

Shunt generator.

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from article Direct-current generator

Cumulative compound generator. The long-shunt connection is seen in this example.

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from article Suicide

Methods of suicide in (left) males and (right) females. The three most prevalent methods of suicide involve firearms, suffocation, and poisoning. Males are much more likely to use firearms, whereas the preferred method in females is poisoning.…

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from article Suicide

Age-adjusted suicide rates in males and females from 1999 to 2017 in the United States. (Credit: National Vital Statistics System, National Center for Health Statistics, Centers for Disease Control and Prevention)

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from article Linear algebra