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from article Messier Catalog
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from article Active sound control
Results of a computer simulation of the sound field produced by two sources of spherical sound waves in air that have identical source strengths and are separated by a distance of 10 m. The sources are out of phase and radiate sound at a frequency…
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from article Active sound control
Feed-forward active noise control system. Elements of the system below the broken line are entirely digital, the filter H operating on the input sequence x to produce the output sequence y. The characteristics of the filter are designed by using the…
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from article Active sound control
Active control system for the suppression of propeller-induced aircraft cabin noise. The digital filters H1 and H2 are designed to minimize the sum of the squared error signals e1–e4.
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from article Active sound control
Distribution of sound pressure level (in decibels on an arbitrary scale) at head height in a 48-seat propeller aircraft (a) before and (b) after the use of a multichannel active noise control system consisting of 16 loudspeakers and 32 microphones.…
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from article Active sound control
Multichannel feed forward active control system for suppressing noise from multiple primary sources.
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from article Active sound control
Performance of a multichannel feed forward system for the active suppression of road-induced noise in a small passenger car at a speed of 60 km/h (37 mi/h). Reference signals were taken from six vibration sensors on the vehicle suspension. The…
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from article Deforestation
View of an area of deforestation in Central Kalimantan, Indonesia. In this case, the land is being cleared to develop areas for intensive rice production. (Credit: Australian National University)
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from article Deforestation
The relationship between forest and nonforest (other) land. Preservation of forest lands includes reforestation and natural regeneration. However, deforestation and natural events can lead to nonforest land. Afforestation (the act or process of…
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from article Deforestation
Natural forest areas (in hectares; 1 hectare = 2.47 acres) in various climatic domains (boreal/polar, temperate, subtropical, and tropical) from 1990 to 2015. The data are derived from the Global Forest Resources Assessment 2015 by the Food and…
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from article Deforestation
Former rainforest in northern Queensland, Australia, that was deforested in the early 1900s and is now used for pasture. (Credit: Rodney Keenan)
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from article Deforestation
Aerial view of deforestation in the Amazon region of Brazil. Clearing of trees in the Amazon rainforest has resulted in the elimination of natural resources and numerous species. (Credit: Luoman/Getty Images)
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from article Symphyla
Scutigerella immaculata. This symphylan is a garden and greenhouse pest. (Photo by Ivo Antušek; BioLib.cz)
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from article Symphyla
Cercus (enlarged view). (Courtesy of Robert T. Allen, Academy of Natural Sciences, Philadelphia; Amanda Lawrence, Electron Microscope Center, Mississippi State University)
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from article Vacuum fusion
Vacuum-fusion methods of analysis.
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from article Cestida
Structure of Cestum veneris.
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from article Precession of equinoxes
Illustration of the celestial sphere, an imaginary sphere of infinite radius centered on the Earth and projected using Earth's celestial poles and celestial equator. (Credit: NASA)
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from article Precession of equinoxes
Motion of the Earth's axis of rotation.
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from article Soil chemistry
Proper soil chemistry helps a green seedling to sprout out from the soil. Soil chemistry controls the availability of plant nutrients within the soil and thus influences plant growth. (Credit: amenic181/Shutterstock)
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from article Soil chemistry
Extensive chemical weathering can remove essential minerals and elements from soil. Typically, only the most insoluble compounds remain in the soil. For example, iron oxides may persist, imparting a reddish-brown color to the soil. (Credit: Stephen…
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from article Soil chemistry
Factors influencing the chemistry of a soil solution. (Credit: Based on an original illustration created by J. F. Hodson)
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from article Walnut
Pith of two species of Juglans: (left) butternut or white walnut (J. cinerea); (right) black walnut (J. nigra). (Photo by Bill Cook, Michigan State University; Bugwood.org)
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from article Walnut
Black walnut (Juglans nigra). (Photo by D. E. Herman, North Dakota State Soil Conservation Committee, U.S. Department of Agriculture–Natural Resources Conservation Service PLANTS Database)
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from article Walnut
Fruits of black walnut (Juglans nigra). (Photo by Rob Routledge, Sault College, Sault Ste. Marie, Ontario, Canada; Bugwood.org)
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from article Walnut
English or Persian walnut (Juglans regia). (Photo by Milan Kořínek)
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from article Walnut
Kernel of English walnut (Juglans regia). (Photo by Piero Amorati, IC Croce, Casalecchio di Reno, Italy; Bugwood.org)
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from article Walnut
Walnut leaf showing symptoms of anthracnose (caused by the fungus Gnomonia leptostyla). (Photo by Pavel Šinkyřík, Czech Republic)
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from article Walnut
Canker disease (caused by the fungus Sirococcus clavigignenti-juglandacearum) on a butternut (Juglans cinerea). (Photo by Mike Ostry, U.S. Department of Agriculture Forest Service)
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from article Comparator
High-gain nonregenerative operational amplifier as voltage comparator.
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from article Comparator
Regenerative operational amplifier as comparator (Schmitt trigger). The input and output voltages are superimposed, showing hysteresis.
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from article Cephalochordata
European lancelet (Branchiostoma lanceolatum). (After J. E. Webb, On the populations of Branchiostoma lanceolatum and their relations with the West African lancelets, Proc. Zool. Soc. Lond., 127:131, 1956)
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from article Clover
Red clover (Trifolium pratense). (Photo by Tom Heutte, U.S. Department of Agriculture Forest Service)
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from article Clover
White clover (Trifolium repens). (Photo by Pavel Šinkyřík)
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from article Clover
Crimson clover (Trifolium incarnatum). (Photo by Pavel Šinkyřík)
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from article Clover
White sweet clover (Melilotus albus). (Photo by Forest and Kim Starr)
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from article Clover
Leaves of clover affected by leaf spot, which is caused by the fungus Pseudopeziza trifolii. (Photo courtesy of the U.S. Department of Agriculture Cooperative Extension Slide Series, Clemson University)
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from article Decision theory
Decision tree for the problem given in the text. Numbers at nodes represent time past alarm (7:00 A.M.), and numbers at branches refer to the decision mode or state of nature.
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from article Decision theory
From of a decision matrix. Oij = outcome corresponding to the interaction of a strategy (Si) and a state of nature (Nj).
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from article Decision theory
Decision tree structure to determine the subjective utility of lottery outcomes.
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from article Decision theory
Hypothetical subjective utility curves.
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from article Power shovel
Comparison of the boom, dipper handle, and dipper for (a) conventional power shovel, (b) hydraulic backhoe, and (c) hydraulic front shovel. A typical lower frame, crawlers, and machinery frame are shown for the hydraulic shovel.
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from article Magnetic materials
Identification of properties related to the magnetic hysteresis loop. Colored area is the magnetization energy lost in every cycle (hysteresis loss).
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from article Magnetic materials
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from article Magnetic materials
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from article Sewage collection systems
Various pipe shapes. (a) Round. (b) Vertically elongated (ellipse). (c) Pipe-arch. (d) Underpass. (e) Arch. (After American Iron and Steel Institute, Handbook of Steel Drainage and Highway Construction Products, 2d ed., 1971)
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from article Sewage collection systems
Band-coupled pipe joints. (a) Typical band coupling; (b) standard corrugated steel pipe band connectors; (c) band angle connector (after American Iron and Steel Institute, Modern Sewer Design, 1980). (d) Details of an O-ring compression joint for…
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from article Sewage collection systems
Diagram of a mechanical compression water stop and seal. (Link Seal, Thunderline Corp., Wayne, Michigan)
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from article Sewage collection systems
Some typical sewer manholes with standard 24-in. (61-cm) cover and frame. (a) Inside drop. (b) Outside drop. (c) Unit for a large sewer. (After R. L. Linsley and J. B. Franzini, Water Resources Engineering, 3d ed., McGraw-Hill, 1979)
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from article Sewage collection systems
Drop manhole detail. (a) Vertical section. (b) Horizontal section (A-A in part a). (After National Clay Pipe Institute, Clay Pipe Engineering Manual, 1962)
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from article Sewage collection systems
Typical house sewer connection. (After Metcalf & Eddy, Inc., and G. Tchobanoglous, Wastewater Engineering: Collection and Pumping of Wastewater, McGraw-Hill, 1981)
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from article Sewage collection systems
Typical stormwater street inlets. (a) Gutter. (b) Curb. (c) Combination; grate placed directly in front of curb opening and depressed. (d) Multiple; undepressed. (After Joint Committee of American Society of Civil Engineers and Water Pollution…
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from article Sewage collection systems
Typical catch basin with removable hood trap for cleanout. (Neenah Foundry Co., Neenah, Wisconsin)
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from article Sewage collection systems
Typical contract plan and profile sheet for sewer lateral. (a) Plan. (b) Profile; numbers on horizontal axis refer to sites with same numbers in part a. MH = manhole. Sta = Station. Inv. El. = Invert elevation. RCP = reinforced concrete pipe. S =…
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from article Sewage collection systems
Hydraulic profile for uniform flow condition, showing values at points U and D.
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from article Sewage collection systems
Hydraulic element graphs for conditions of partial flow in terms of full section. (a) Pipe-arch section. (b) Circular section. (After American Iron and Steel Institute, Modern Sewer Design, 1980)
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from article Buxbaumiidae
Morphological features of Buxbaumiidae. (a) Sporophyte of Buxbaumia aphylla (after W. H. Welch, Mosses of Indiana, Indiana Department of Conservation, 1957). Diphyscium foliosum (b) habit sketch, (c) leaves and (d) perichaetial leaf (after H. S.…
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from article Rhinoceros
Black rhinoceros (Diceros bicornis). (Credit: Lloyd Glenn Ingles; copyright © California Academy of Sciences)
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from article Ferret
An endangered black-footed ferret (Mustela nigripes). (Photo copyright © Joseph Dougherty)
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from article Siphonostomatoida
Siphonostomatoida. (a) Representative siphonostomatoid mandible; (b) brachiform maxilla (after Z. Kabata, Parasitic Copepoda of British Fishes, vol. 152, Ray Society, London, 1979). (c) Representative female caligid; (d) female Pennella (after P. A.…
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from article Holothuroidea
Cucumaria, a representative holothurian.
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from article Holothuroidea
Holothurian anatomy.
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from article Engineering
Test firing of NASA’s 3D-printed rocket engine nozzle. 3D printing allows engineers to test new prototypes, including objects designed with multiple materials, speeding the development process and time. (Credit: NASA/MSFC/David Olive)
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from article Turboprop
Typical turboprop configurations. (a) Fixed-turbine turboprop. (b) Free-turbine turboprop. (c) Offset-gearbox turboprop. (d) Counterrotating turboprop. (e) Unducted fan, an ungeared, counterrotating, pusher turboprop. (After R. C. Hawkins, Unducted…
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from article Turboprop
Typical turboprop installations. (a) Conventional tractor-type single-rotation turboprop (Saab Corp.). (b) Unducted fan, a pusher-type counterrotating turboprop (GE Aircraft Engines).
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from article Thermostat
Typical heat-cool thermostat. (Honeywell Inc.)
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from article Thermostat
Comparison of temperature variations using a timed on-off thermostat with and without heat anticipation.
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from article Cosmic background radiation
Timeline of the origin and evolution of the universe from a hot, dense state (left) to the current star-and galaxy-filled cosmos that arose over eons of the universe’s history and through today (right). The cosmic microwave background, labeled the…
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from article Cosmic background radiation
The most detailed map ever made of the cosmic microwave background, a snapshot of the universe at 380,000 years of age, obtained by the Planck spacecraft during its observing run from 2009 to 2013. Anisotropies—tiny temperature fluctuations—are…
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from article Cosmic background radiation
The 15-meter horn antenna at Bell Telephone Laboratories in Holmdel, New Jersey where the first detection of the cosmic microwave background was made. (Credit: NASA)
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from article Plant physiology
The process of photosynthesis is a key feature of plant physiology. Chloroplasts (cell plastids that contain chlorophyll) use solar energy to manufacture carbohydrates and other large molecules. Mitochondria break down these molecules, thereby…
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from article Plant physiology
Adoption of genetically modified crops in the United States for the period of 1996 to 2016. Herbicide-tolerant (HT) soybeans, cotton, and corn have been modified genetically to survive the application of specific herbicides that previously would…
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from article Bridge
Corpus Christi Harbor Bridge, a through-arch bridge, Corpus Christi, Texas, USA. (Credit: Brian Kanof/McGraw-Hill Education)
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from article Bridge
Typical bridge elevation.
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from article Bridge
Cast-in-place concrete deck under construction. (Courtesy of Lian Duan)
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from article Bridge
A typical steel-grid bridge deck.
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from article Bridge
Typical components of orthotropic deck bridges with (a) open ribs and (b) closed ribs. (From M. S. Troitsky, Orthotropic Steel Deck Bridges, 2d ed., JFL Arch Welding Foundation, Cleveland, OH, 1987. Courtesy of The James F. Lincoln Arc Welding…
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from article Bridge
Typical shapes of small piers for small bridges.
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from article Bridge
Typical abutments: (a) wingless; (b) straight wing; (c) U-shaped; (d) beveled wing; (e) arch bridge abutment.
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from article Bridge
Typical shallow foundation. P = vertical load, D = embedment depth, B = width.
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from article Bridge
Typical deep foundations: (a) anchor, (b) shaft, (c) pile, and (d) caisson.
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from article Humidification
An example of a psychrometric chart.
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from article Humidification
Schematic of air conditioning humidifier.
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from article Humidification
Cutaway view of large industrial counterflow cooling tower. (Fluor Products Co.)
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from article Process engineering
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from article Process engineering
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from article Process engineering
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from article Process engineering
Twelve degrees of freedom of a workpiece.
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from article Process engineering
Three views of a workpiece.
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from article Zosterophyllopsida
Examples of Devonian Zosterophyllopsida. (a) Reconstruction of the Early Devonian Zosterophyllum rhenanum, here depicted as an aquatic plant (after R. Kräusel and H. Weyland, Neue Pflanzenfunde im rheinischen Unterdevon, Palaeontographica B,…
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from article Optical material
Transmission range for a variety of optical materials. The bars indicate the wavelength region for which the external transmittance for a 1-mm-thick sample of the material is greater than 10% when measured at room temperature. The wavelength scale…
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from article Optical material
Transmission versus wavelength for several optical materials. The wavelength scale is logarithmic.
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from article Optical material
Refractive index versus wavelength for several optical materials. The wavelength scale is logarithmic.
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from article Optical material
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from article Optical material
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from article Calanoida
Diaptomus. (a) Lateral view of male. (b) Dorsal view of female.
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from article Ophiuroidea
Representative ophiuroids, which have a quite distinctive shape. (a) Ophiopeza cylindrica (alternatively, Pectinura cylindrica). (b) Asteroporpa australiensis (alternatively, Astroporpa wilsoni). (c) Gorgonocephalus chilensis.
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from article Ophiuroidea
External features of the ophiuroid Amphiura. (a) Aboral view. (b) Adoral view.
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from article Forging
Closed-die forging terminology.
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from article Forging
Formation of a defect in closed-die forging.
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from article Forging
Operation principle of swaging machine.
