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from article Bridge maintenance
Under-bridge snooper truck during bridge inspection. (Courtesy Lian Duan)
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from article Bridge maintenance
Repair of concrete I-girder by replacement of damaged concrete.
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from article Bridge maintenance
Strengthening of a steel I-girder by adding new steel plates to flanges.
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from article Bridge maintenance
Strengthening a steel girder by applying external post-tensioning force.
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from article Bridge maintenance
A typical steel jacket for a reinforced-concrete column.
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from article Bridge maintenance
Built-up steel member retrofit. (Courtesy Lian Duan)
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from article Bridge maintenance
Seismic isolation bearing installed in the Antioch Bridge, California. (Courtesy Lian Duan)
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from article Bridge maintenance
A damper installed in the west span of the San Francisco–Oakland Bay Bridge, California. (Courtesy Lian Duan)
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from article Video disk
DVD operational principles.
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from article Process control
Optimum operation of distillation column.
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from article Process control
Estimation of product quality by on-line computer.
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from article Process control
Block diagram illustrating feedback loop around process.
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from article Process control
Feedback and feedforward control on continuous stirred chemical reactor.
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from article Process control
Block diagram of typical feedforward control.
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from article Process control
Closed-loop fuzzy process control.
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from article Process control
Neural network for process modeling and control.
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from article Process control
Local computer system.
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from article Process control
Schematic example of modern distributed control system.
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from article Manganese
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from article Crystal growth
Schematic representation of cross section of crystal at three stages of regular growth.
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from article Crystal growth
A model of a crystal surface showing the inequivalent binding sites at which the atoms labeled A and B are located. (General Electric Co.)
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from article Crystal growth
A dendrite. Growth direction is upward for primary protuberances; side branches grow perpendicularly; side branches on the side branches are also seen growing perpendicularly. (After W. Kurz and D. J. Fisher, Fundamentals of Solidification, Trans…
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from article Crystal growth
Hypothetical binary system AB having simple compound formation. (a) Phase diagram. (b) Corresponding partial pressure curves. The extent of the stoichiometry range is greatly exaggerated for illustration.
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from article Crystal growth
Czochralski crystal growth and temperature distribution.
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from article Crystal growth
Vertical Bridgman crystal and temperature distribution.
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from article Crystal growth
An isotherm in the aluminum-gallium-arsenic (Al-Ga-As) ternary phase diagram. Each corner represents a pure element and each point within the diagram a unique composition, all at a given temperature. Each composition on the liquidus is in…
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from article Crystal growth
Molecular-beam epitaxy apparatus.
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from article Crystal growth
Cross section of a gallium arsenide–aluminum arsenide (GaAs–AlAs) single crystal with individual gallium arsenide and aluminum arsenide layers each about 5 × 10−10 m thick.
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from article Oscillatory reaction
Oscillatory behavior in a sulfuric acid medium containing potassium bromate, malonic acid, and cerous nitrate. The upper curve is the potential (in unspecified units) of a tungsten electrode and is related to the concentration ratio of…
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from article Oscillatory reaction
Rotating spiral bands of oxidation in a thin layer of solution containing the same reagents as in Fig. 1 except that the redox indicator ferrous phenanthroline has been substituted for cerous ion. (Courtesy of Prof. A. T. Winfree, University of…
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from article Oscillatory reaction
Layers of crystallization from an initially uniform magma in the Skaergaard Intrusion in Greenland. (From A. R. McBirney and R. M. Noyes, Crystallization and layering of the Skaergaard Intrusion, J. Petrol., 20:487–554, 1979)
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from article Risk assessment and management
Risk management and assessment involves solving problems such as the lifetime risk of occupational exposure to radiation from nuclear power reactors. (Copyright © Philip Lange/Shutterstock.com)
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from article Risk assessment and management
Risk analysis, assessment, and management.
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from article Stripping (chemical engineering)
Stripping column and accessory equipment.
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from article Stripping (chemical engineering)
Column operating diagrams. (a) Absorption. (b) Stripping.
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from article Phase-locked loops
Basic components of a phase-locked loop.
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from article Phase-locked loops
Diode phase detector.
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from article Phase-locked loops
Double-balanced phase detector. (a) Circuit. (b) Waveforms.
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from article Phase-locked loops
Digital phase/frequency detector. Q = output; Q = inverting output.
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from article Phase-locked loops
Loop filter configurations. (a) Passive. (b) Active.
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from article Mixer
Linear mixers. (a) Passive linear mixer based on a resistive summing network. (b) Active linear mixer with an operational amplifier.
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from article Mixer
Balanced modulator (nonlinear mixer). Only signal paths are shown. Biasing must be added.
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from article Sol-gel process
Flow chart showing the sol-gel methods used to prepare bulk glasses, thin films of glass or ceramics, and powders; the powders are then sintered to produce ceramics.
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from article Behavioral psychophysics
Diagram of the apparatus for measuring the pigeon's absolute visual threshold. (After D S. Blough, A method for obtaining psychophysical thresholds from the pigeon, J. Exp. Anal. Behav., 1:31–43, 1958)
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from article Systems integration
Systems integration activity, showing the architecture for the system.
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from article Systems integration
Tactical and strategic perspective of systems integration, showing essential elements.
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from article Straight-line mechanism
Classical four-bar linkage straight-line mechanisms: (a) Watt, (b) Russell, (c) Evans, (d) Roberts, (e) Chelbyshev, (f) Peaucellier.
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from article Straight-line mechanism
Geared straight-line mechanisms. (a) Cardan circle pair; small-gear diameter = 0.5 large-gear diameter. (b) Standard gear; gear diameter 2 = 0.5 gear diameter 1; gear diameters 3 and 4 are arbitrary.
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from article Straight-line mechanism
Translating follower cam mechanism with an instantaneously equivalent slider-crank representation.
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from article Straight-line mechanism
Chain/belt–sprocket combination.
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from article Supercritical wing
Comparison of airflow about airfoils. (a) Conventional airfoil, Mach number = 0.7. (b) Supercritical airfoil, Mach number = 0.8
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from article Electric transient
Resistance and inductance in series.
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from article Electric transient
Resistance and capacitance in series.
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from article Electric transient
Resistance, inductance, and capacitance in series for three cases.
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from article Electric transient
RLC circuit with alternating current source.
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from article Electric transient
Causes of electric transients in power systems.
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from article Electric transient
Analysis of electric transients involving both harmonic oscillation and traveling waves. (a) Configuration of power system for study of transient recovery voltage (TRV). (b) Model for evaluating steady state before breaker opening. (c) Model for…
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from article Electric transient
Graphical interpretation of electromagnetic transients on transmission line. (a–f) Voltage profiles along line. (g) Derived voltage at beginning of line as a function of time.
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from article Electric transient
Transient recovery voltages (TRVs). (a) TRVs on source side (vS) and line side (vl). (b) TRV across circuit breaker (vB).
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from article Electric transient
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from article Regular polytopes
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from article Regular polytopes
Two regular polyhedrons. (a) Dodecahedron {5,3}. (b) Icosahedron {3,5}.
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from article Regular polytopes
Two of the six regular four-dimensional polytopes. (a) The 5-cell {3,3,3}. (b) The 8-cell {4,3,3}.
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from article Surface and interfacial chemistry
Scheme for reducing bacterial adhesion at an implanted biomaterial.
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from article Surface and interfacial chemistry
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from article Surface and interfacial chemistry
Microscopic surface structures. (a) Surface atoms occupying positions other than the bulk-terminated locations. The first interlayer spacing d12 is greater than the bulk interlayer spacing d34. The second interlayer spacing d23 is smaller than the…
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from article Surface and interfacial chemistry
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from article Surface and interfacial chemistry
Processes of electron spectroscopies. (a) Auger electron spectroscopy. A core-level electron is ejected by excitation from the incident high-energy electron. A second electron fills the vacancy left by the ejected electron. The third electron, the…
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from article Surface and interfacial chemistry
Typical configuration for application of optical spectroscopies to surface analysis. (a) Transmission. (b) External or specular reflection. (c) Internal reflection. I = reflected light intensity. I0 = initial light intensity. θi = angle of incidence…
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from article Surface and interfacial chemistry
Scanning tunneling microscopy and images for (a) constant-current mode and (b) constant-height mode; shown only in x dimension for simplicity.
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from article Ferrite devices
Plot of magnetic induction B as a function of magnetic field strength H.
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from article Ferrite devices
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from article Subsonic flight
Flow around an airfoil (a) without circulation and (b) with circulation.
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from article Subsonic flight
Flow occurring at small Reynolds numbers (a) around a circular cylinder and (b) around an elliptical cylinder. (From L. Prandtl and O.G. Tietjens, Applied Hydro- and Aeromechanics, Dover, 1934)
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from article Subsonic flight
Flow pattern on an airfoil in a real fluid. (a) Low angle of attack, unstalled. (b) High angle of attack, stalled. (From P. P. Ewald, T. Poschl, and L. Prandtl, Physics of Solids and Fluids, Blackie, 1936)
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from article Subsonic flight
Dimensionless laminar boundary layer and turbulent boundary layer profiles.
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from article Subsonic flight
Boundary-layer growth on a sphere for R > 550,000. The boundary-layer thickness is exaggerated in the diagram for clarity. ( After J. H. Dwinnell, Principles of Aerodynamics, McGraw-Hill, 1949)
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from article Subsonic flight
Representation of a rectangular wing by a horseshoe vortex.
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from article Fiber crops
Cotton, the most important textile fiber crop grown in the world. (Photo by Gary Kramer, Natural Resources Conservation Service, U.S. Department of Agriculture)
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from article Analytic hierarchy
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from article Analytic hierarchy
Analytic hierarchy used to assist a family in buying a new car.
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from article Analytic hierarchy
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from article Analytic hierarchy
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from article Analytic hierarchy
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from article Analytic hierarchy
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from article Analytic hierarchy
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from article Pantograph
Similar triangles of a pantograph.
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from article Parametric amplifier
Negative-resistance-type parametric amplifier.
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from article Valve train
Valve for a four-cycle engine. (a) Valve-timing diagram. (b) Valve train with the camshaft in the cylinder block and the valves in the cylinder head. (Pontiac Division, General Motors Corp.)
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from article Valve train
Valve train of a V-6 four-cycle engine with the valves and two camshafts located in each cylinder head. The cams act directly on cup-type cam followers to open the valves. (Ford Motor Co.)
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from article Lignin
Chemical formula representation of lignin, in which bold lines represent linkages between individual phenylpropane lignin monomer units, and shaded area represents the structure of a typical lignin model compound.
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from article Coal liquefaction
Processing steps in direct coal liquefaction. Broken lines represent optional steps or flow streams.
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from article Chromium
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from article Reproductive behavior
The mating of dragonflies encompasses a number of reproductive behaviors. Typically, the male is in front and the female is behind. If the female is willing to mate, she bends her abdomen forward to collect sperm from the male's accessory genitalia,…
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from article Reproductive behavior
Sage-grouse lek. Males stake out and defend territories on a traditional breeding ground. Females breed with males in selected territories. (Credit: U.S. Fish and Wildlife Service)
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from article Reproductive behavior
Two bull northern elephant seals fighting for dominance on the beach. (Credit: eoind/Getty Images)
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from article Reproductive behavior
Natterjack toad giving a mating call with its vocal sac expanded. (Credit: Bobby Bok)
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from article Reproductive behavior
Mating behavior of sticklebacks: (a) zigzag dance of a male, which leads a female to the nest; (b) the male stimulates the female in the nest to lay eggs; (c) schematic portrayal of the events in a courtship sequence. (Credit: Based on original…
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from article Reproductive behavior
Lordosis in a female rodent. When mounted, the females of many mammalian species adopt the lordotic posture, rendering copulation possible. Note the concave arching of the spine. (Credit: Based on an original drawing by L. C. Drickamer and S. H.…
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from article Reproductive behavior
A black-browed albatross feeding a chick. This is one example in which parental care may be extensive and prolonged. (Credit: Vetta/Getty Images)
