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148-402: Sonar ( sound navigation and ranging or sonic navigation and ranging ) is a technique that uses sound propagation (usually underwater, as in submarine navigation ) to navigate , measure distances ( ranging ), communicate with or detect objects on or under the surface of the water, such as other vessels. "Sonar" can refer to one of two types of technology: passive sonar means listening for

296-429: A root mean square (RMS) value. For example, 1 Pa RMS sound pressure (94 dBSPL) in atmospheric air implies that the actual pressure in the sound wave oscillates between (1 atm − 2 {\displaystyle -{\sqrt {2}}} Pa) and (1 atm + 2 {\displaystyle +{\sqrt {2}}} Pa), that is between 101323.6 and 101326.4 Pa. As the human ear can detect sounds with

444-566: A transducer , made of thin quartz crystals carefully glued between two steel plates, and a hydrophone to detect the returned echo . By emitting a high-frequency pulse from the transducer, and measuring the amount of time it takes to hear an echo from the sound waves bouncing off an object, one can calculate the distance to that object. Piezoelectric devices found homes in many fields. Ceramic phonograph cartridges simplified player design, were cheap and accurate, and made record players cheaper to maintain and easier to build. The development of

592-403: A ceramic disc. Ultrasonic transducers that transmit sound waves through air had existed for quite some time but first saw major commercial use in early television remote controls. These transducers now are mounted on several car models as an echolocation device, helping the driver determine the distance from the car to any objects that may be in its path. The nature of the piezoelectric effect

740-650: A gas, liquid or solid. In human physiology and psychology , sound is the reception of such waves and their perception by the brain . Only acoustic waves that have frequencies lying between about 20 Hz and 20 kHz, the audio frequency range, elicit an auditory percept in humans. In air at atmospheric pressure, these represent sound waves with wavelengths of 17 meters (56 ft) to 1.7 centimeters (0.67 in). Sound waves above 20  kHz are known as ultrasound and are not audible to humans. Sound waves below 20 Hz are known as infrasound . Different animal species have varying hearing ranges . Sound

888-663: A given area as modified by the environment and understood by people, in context of the surrounding environment. There are, historically, six experimentally separable ways in which sound waves are analysed. They are: pitch , duration , loudness , timbre , sonic texture and spatial location . Some of these terms have a standardised definition (for instance in the ANSI Acoustical Terminology ANSI/ASA S1.1-2013 ). More recent approaches have also considered temporal envelope and temporal fine structure as perceptually relevant analyses. Pitch

1036-411: A hydrophone/transducer receives a specific interrogation signal it responds by transmitting a specific reply signal. To measure distance, one transducer/projector transmits an interrogation signal and measures the time between this transmission and the receipt of the other transducer/hydrophone reply. The time difference, scaled by the speed of sound through water and divided by two, is the distance between

1184-737: A material could be made up of an inert matrix with a separate piezo-active component. PVDF exhibits piezoelectricity several times greater than quartz. The piezo-response observed from PVDF is about 20–30 pC/N. That is an order of 5–50 times less than that of piezoelectric ceramic lead zirconate titanate (PZT). The thermal stability of the piezoelectric effect of polymers in the PVDF family (i.e. vinylidene fluoride co-poly trifluoroethylene) goes up to 125 °C. Some applications of PVDF are pressure sensors, hydrophones, and shock wave sensors. Due to their flexibility, piezoelectric composites have been proposed as energy harvesters and nanogenerators. In 2018, it

1332-420: A material generates an electric potential in response to a temperature change, was studied by Carl Linnaeus and Franz Aepinus in the mid-18th century. Drawing on this knowledge, both René Just Haüy and Antoine César Becquerel posited a relationship between mechanical stress and electric charge; however, experiments by both proved inconclusive. The first demonstration of the direct piezoelectric effect

1480-405: A mechanical strain resulting from an applied electric field . For example, lead zirconate titanate crystals will generate measurable piezoelectricity when their static structure is deformed by about 0.1% of the original dimension. Conversely, those same crystals will change about 0.1% of their static dimension when an external electric field is applied. The inverse piezoelectric effect is used in

1628-405: A medium such as air, water and solids as longitudinal waves and also as a transverse wave in solids . The sound waves are generated by a sound source, such as the vibrating diaphragm of a stereo speaker. The sound source creates vibrations in the surrounding medium. As the source continues to vibrate the medium, the vibrations propagate away from the source at the speed of sound , thus forming

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1776-500: A narrow arc, although the beam may be rotated, relatively slowly, by mechanical scanning. Particularly when single frequency transmissions are used, the Doppler effect can be used to measure the radial speed of a target. The difference in frequency between the transmitted and received signal is measured and converted into a velocity. Since Doppler shifts can be introduced by either receiver or target motion, allowance has to be made for

1924-488: A particular pitch is determined by pre-conscious examination of vibrations, including their frequencies and the balance between them. Specific attention is given to recognising potential harmonics. Every sound is placed on a pitch continuum from low to high. For example: white noise (random noise spread evenly across all frequencies) sounds higher in pitch than pink noise (random noise spread evenly across octaves) as white noise has more high frequency content. Duration

2072-422: A porous polymeric film. Under an electric field, charges form on the surface of the voids forming dipoles. Electric responses can be caused by any deformation of these voids. The piezoelectric effect can also be observed in polymer composites by integrating piezoelectric ceramic particles into a polymer film. A polymer does not have to be piezo-active to be an effective material for a polymer composite. In this case,

2220-486: A pulse to reception is measured and converted into a range using the known speed of sound. To measure the bearing , several hydrophones are used, and the set measures the relative arrival time to each, or with an array of hydrophones, by measuring the relative amplitude in beams formed through a process called beamforming . Use of an array reduces the spatial response so that to provide wide cover multibeam systems are used. The target signal (if present) together with noise

2368-423: A rank-3 tensor. Such a relabeled notation is often called Voigt notation . Whether the shear strain components S 4 , S 5 , S 6 are tensor components or engineering strains is another question. In the equation above, they must be engineering strains for the 6,6 coefficient of the compliance matrix to be written as shown, i.e., 2( s 11  −  s 12 ). Engineering shear strains are double

2516-520: A steel tube, vacuum-filled with castor oil , and sealed. The tubes then were mounted in parallel arrays. The standard US Navy scanning sonar at the end of World War II operated at 18 kHz, using an array of ADP crystals. Desired longer range, however, required use of lower frequencies. The required dimensions were too big for ADP crystals, so in the early 1950s magnetostrictive and barium titanate piezoelectric systems were developed, but these had problems achieving uniform impedance characteristics, and

2664-448: A stockpile of utilizable soil are known aids for any extraction event. For minimizing air quality effects, modeling and simulation still needs to occur to fully understand what mitigation methods are required. The extraction of lead-free piezoceramic components has not grown to a significant scale at this time, but from early analysis, experts encourage caution when it comes to environmental effects. Fabricating lead-free piezoceramics faces

2812-521: A system later tested in Boston Harbor, and finally in 1914 from the U.S. Revenue Cutter Miami on the Grand Banks off Newfoundland . In that test, Fessenden demonstrated depth sounding, underwater communications ( Morse code ) and echo ranging (detecting an iceberg at a 2-mile (3.2 km) range). The " Fessenden oscillator ", operated at about 500 Hz frequency, was unable to determine

2960-582: A target ahead of the attacker and still in ASDIC contact. These allowed a single escort to make better aimed attacks on submarines. Developments during the war resulted in British ASDIC sets that used several different shapes of beam, continuously covering blind spots. Later, acoustic torpedoes were used. Early in World War II (September 1940), British ASDIC technology was transferred for free to

3108-411: A variation of the polarization strength, its direction or both, with the details depending on: 1. the orientation of P within the crystal; 2. crystal symmetry ; and 3. the applied mechanical stress. The change in P appears as a variation of surface charge density upon the crystal faces, i.e. as a variation of the electric field extending between the faces caused by a change in dipole density in

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3256-466: A wide range of amplitudes, sound pressure is often measured as a level on a logarithmic decibel scale. The sound pressure level (SPL) or L p is defined as Since the human ear does not have a flat spectral response , sound pressures are often frequency weighted so that the measured level matches perceived levels more closely. The International Electrotechnical Commission (IEC) has defined several weighting schemes. A-weighting attempts to match

3404-411: Is bistatic operation . When more transmitters (or more receivers) are used, again spatially separated, it is multistatic operation . Most sonars are used monostatically with the same array often being used for transmission and reception. Active sonobuoy fields may be operated multistatically. Active sonar creates a pulse of sound, often called a "ping", and then listens for reflections ( echo ) of

3552-415: Is actually more harmful to the environment. Most of the concerns with KNN, specifically its Nb 2 O 5 component, are in the early phase of its life cycle before it reaches manufacturers. Since the harmful impacts are focused on these early phases, some actions can be taken to minimize the effects. Returning the land as close to its original form after Nb 2 O 5 mining via dam deconstruction or replacing

3700-488: Is also known as the Newton–Laplace equation. In this equation, K is the elastic bulk modulus, c is the velocity of sound, and ρ {\displaystyle \rho } is the density. Thus, the speed of sound is proportional to the square root of the ratio of the bulk modulus of the medium to its density. Those physical properties and the speed of sound change with ambient conditions. For example,

3848-418: Is also used for the equipment used to generate and receive the sound. The acoustic frequencies used in sonar systems vary from very low ( infrasonic ) to extremely high ( ultrasonic ). The study of underwater sound is known as underwater acoustics or hydroacoustics . The first recorded use of the technique was in 1490 by Leonardo da Vinci , who used a tube inserted into the water to detect vessels by ear. It

3996-399: Is an undesirable component that obscures a wanted signal. However, in sound perception it can often be used to identify the source of a sound and is an important component of timbre perception (see below). Soundscape is the component of the acoustic environment that can be perceived by humans. The acoustic environment is the combination of all sounds (whether audible to humans or not) within

4144-478: Is characterized by) its unique sounds. Many species, such as frogs, birds, marine and terrestrial mammals , have also developed special organs to produce sound. In some species, these produce song and speech . Furthermore, humans have developed culture and technology (such as music, telephone and radio) that allows them to generate, record, transmit, and broadcast sound. Noise is a term often used to refer to an unwanted sound. In science and engineering, noise

4292-453: Is closely related to the occurrence of electric dipole moments in solids. The latter may either be induced for ions on crystal lattice sites with asymmetric charge surroundings (as in BaTiO 3 and PZTs ) or may directly be carried by molecular groups (as in cane sugar ). The dipole density or polarization (dimensionality [C·m/m ] ) may easily be calculated for crystals by summing up

4440-424: Is commonly used for diagnostics and treatment. Infrasound is sound waves with frequencies lower than 20 Hz. Although sounds of such low frequency are too low for humans to hear as a pitch, these sound are heard as discrete pulses (like the 'popping' sound of an idling motorcycle). Whales, elephants and other animals can detect infrasound and use it to communicate. It can be used to detect volcanic eruptions and

4588-445: Is defined as "(a) Oscillation in pressure, stress, particle displacement, particle velocity, etc., propagated in a medium with internal forces (e.g., elastic or viscous), or the superposition of such propagated oscillation. (b) Auditory sensation evoked by the oscillation described in (a)." Sound can be viewed as a wave motion in air or other elastic media. In this case, sound is a stimulus. Sound can also be viewed as an excitation of

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4736-418: Is heard; specif.: a. Psychophysics. Sensation due to stimulation of the auditory nerves and auditory centers of the brain, usually by vibrations transmitted in a material medium, commonly air, affecting the organ of hearing. b. Physics. Vibrational energy which occasions such a sensation. Sound is propagated by progressive longitudinal vibratory disturbances (sound waves)." This means that the correct response to

4884-453: Is its zero aging characteristics; the crystal keeps its parameters even over prolonged storage. Another application was for acoustic homing torpedoes. Two pairs of directional hydrophones were mounted on the torpedo nose, in the horizontal and vertical plane; the difference signals from the pairs were used to steer the torpedo left-right and up-down. A countermeasure was developed: the targeted submarine discharged an effervescent chemical, and

5032-456: Is mostly due to its molecular structure. There are two types of bulk polymers: amorphous and semi-crystalline . Examples of semi-crystalline polymers are polyvinylidene fluoride (PVDF) and its copolymers , polyamides , and parylene-C . Non-crystalline polymers, such as polyimide and polyvinylidene chloride (PVDC), fall under amorphous bulk polymers. Voided charged polymers exhibit the piezoelectric effect due to charge induced by poling of

5180-734: Is not as high as the response for ceramics; however, polymers hold properties that ceramics do not. Over the last few decades, non-toxic, piezoelectric polymers have been studied and applied due to their flexibility and smaller acoustical impedance . Other properties that make these materials significant include their biocompatibility , biodegradability , low cost, and low power consumption compared to other piezo-materials (ceramics, etc.). Piezoelectric polymers and non-toxic polymer composites can be used given their different physical properties. Piezoelectric polymers can be classified by bulk polymers, voided charged polymers ("piezoelectrets"), and polymer composites. A piezo-response observed by bulk polymers

5328-468: Is only elicited by applying a mechanical load. For them the stress can be imagined to transform the material from a nonpolar crystal class ( P  = 0) to a polar one, having P  ≠ 0. Many materials exhibit piezoelectricity. Ceramics with randomly oriented grains must be ferroelectric to exhibit piezoelectricity. The occurrence of abnormal grain growth (AGG) in sintered polycrystalline piezoelectric ceramics has detrimental effects on

5476-465: Is perceived as how "long" or "short" a sound is and relates to onset and offset signals created by nerve responses to sounds. The duration of a sound usually lasts from the time the sound is first noticed until the sound is identified as having changed or ceased. Sometimes this is not directly related to the physical duration of a sound. For example; in a noisy environment, gapped sounds (sounds that stop and start) can sound as if they are continuous because

5624-457: Is perceived as how "low" or "high" a sound is and represents the cyclic, repetitive nature of the vibrations that make up sound. For simple sounds, pitch relates to the frequency of the slowest vibration in the sound (called the fundamental harmonic). In the case of complex sounds, pitch perception can vary. Sometimes individuals identify different pitches for the same sound, based on their personal experience of particular sound patterns. Selection of

5772-422: Is perceptible by humans has frequencies from about 20 Hz to 20,000 Hz. In air at standard temperature and pressure , the corresponding wavelengths of sound waves range from 17 m (56 ft) to 17 mm (0.67 in). Sometimes speed and direction are combined as a velocity vector ; wave number and direction are combined as a wave vector . Transverse waves , also known as shear waves, have

5920-415: Is the source level , PL is the propagation loss (sometimes referred to as transmission loss ), TS is the target strength , NL is the noise level , AG is the array gain of the receiving array (sometimes approximated by its directivity index) and DT is the detection threshold . In reverberation-limited conditions at initial detection (neglecting array gain): where RL is the reverberation level , and

6068-535: Is the matrix for the direct piezoelectric effect and [ d ] is the matrix for the converse piezoelectric effect. The superscript E indicates a zero, or constant, electric field; the superscript T indicates a zero, or constant, stress field; and the superscript t stands for transposition of a matrix . Notice that the third order tensor d {\displaystyle {\mathfrak {d}}} maps vectors into symmetric matrices. There are no non-trivial rotation-invariant tensors that have this property, which

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6216-426: Is then passed through various forms of signal processing , which for simple sonars may be just energy measurement. It is then presented to some form of decision device that calls the output either the required signal or noise. This decision device may be an operator with headphones or a display, or in more sophisticated sonars this function may be carried out by software. Further processes may be carried out to classify

6364-418: Is used in some types of music. Piezoelectricity The piezoelectric effect results from the linear electromechanical interaction between the mechanical and electrical states in crystalline materials with no inversion symmetry . The piezoelectric effect is a reversible process : materials exhibiting the piezoelectric effect also exhibit the reverse piezoelectric effect, the internal generation of

6512-399: Is very low, several orders of magnitude less than the original signal. Even if the reflected signal was of the same power, the following example (using hypothetical values) shows the problem: Suppose a sonar system is capable of emitting a 10,000 W/m signal at 1 m, and detecting a 0.001 W/m signal. At 100 m the signal will be 1 W/m (due to the inverse-square law ). If

6660-437: Is why there are no isotropic piezoelectric materials. The strain-charge for a material of the 4mm (C 4v ) crystal class (such as a poled piezoelectric ceramic such as tetragonal PZT or BaTiO 3 ) as well as the 6mm crystal class may also be written as (ANSI IEEE 176): where the first equation represents the relationship for the converse piezoelectric effect and the latter for the direct piezoelectric effect. Although

6808-738: The Titanic disaster of 1912. The world's first patent for an underwater echo-ranging device was filed at the British Patent Office by English meteorologist Lewis Fry Richardson a month after the sinking of Titanic , and a German physicist Alexander Behm obtained a patent for an echo sounder in 1913. The Canadian engineer Reginald Fessenden , while working for the Submarine Signal Company in Boston , Massachusetts, built an experimental system beginning in 1912,

6956-535: The Group III – V and II – VI materials, due to polarization of ions under applied stress and strain. This property is common to both the zincblende and wurtzite crystal structures. To first order, there is only one independent piezoelectric coefficient in zincblende , called e 14 , coupled to shear components of the strain. In wurtzite , there are instead three independent piezoelectric coefficients: e 31 , e 33 and e 15 . The semiconductors where

7104-458: The Royal Navy had five sets for different surface ship classes, and others for submarines, incorporated into a complete anti-submarine system. The effectiveness of early ASDIC was hampered by the use of the depth charge as an anti-submarine weapon. This required an attacking vessel to pass over a submerged contact before dropping charges over the stern, resulting in a loss of ASDIC contact in

7252-475: The United States , USSR , and Japan discovered a new class of synthetic materials, called ferroelectrics , which exhibited piezoelectric constants many times higher than natural materials. This led to intense research to develop barium titanate and later lead zirconate titanate materials with specific properties for particular applications. One significant example of the use of piezoelectric crystals

7400-401: The equilibrium pressure, causing local regions of compression and rarefaction , while transverse waves (in solids) are waves of alternating shear stress at right angle to the direction of propagation. Sound waves may be viewed using parabolic mirrors and objects that produce sound. The energy carried by an oscillating sound wave converts back and forth between the potential energy of

7548-483: The hearing range for humans or sometimes it relates to a particular animal. Other species have different ranges of hearing. For example, dogs can perceive vibrations higher than 20 kHz. As a signal perceived by one of the major senses , sound is used by many species for detecting danger , navigation , predation , and communication. Earth's atmosphere , water , and virtually any physical phenomenon , such as fire, rain, wind, surf , or earthquake, produces (and

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7696-550: The hull or become flooded, the 60 Hz sound from the windings can be emitted from the submarine or ship. This can help to identify its nationality, as all European submarines and nearly every other nation's submarine have 50 Hz power systems. Intermittent sound sources (such as a wrench being dropped), called "transients," may also be detectable to passive sonar. Until fairly recently, an experienced, trained operator identified signals, but now computers may do this. Passive sonar systems may have large sonic databases , but

7844-577: The phase transition temperatures converge at room temperature. The introduction of the MPB improves piezoelectric properties, but if a PPB is introduced, the material becomes negatively affected by temperature. Research is ongoing to control the type of phase boundaries that are introduced through phase engineering, diffusing phase transitions, domain engineering, and chemical modification. A piezoelectric potential can be created in any bulk or nanostructured semiconductor crystal having non central symmetry, such as

7992-476: The strain-charge form is: where d {\displaystyle {\mathfrak {d}}} is the piezoelectric tensor and the superscript t stands for its transpose. Due to the symmetry of d {\displaystyle {\mathfrak {d}}} , d i j k t = d k j i = d k i j {\displaystyle d_{ijk}^{t}=d_{kji}=d_{kij}} . In matrix form, where [ d ]

8140-491: The 1930s American engineers developed their own underwater sound-detection technology, and important discoveries were made, such as the existence of thermoclines and their effects on sound waves. Americans began to use the term SONAR for their systems, coined by Frederick Hunt to be the equivalent of RADAR . In 1917, the US Navy acquired J. Warren Horton 's services for the first time. On leave from Bell Labs , he served

8288-498: The 1970s, compounds of rare earths and iron were discovered with superior magnetomechanic properties, namely the Terfenol-D alloy. This made possible new designs, e.g. a hybrid magnetostrictive-piezoelectric transducer. The most recent of these improved magnetostrictive materials is Galfenol . Other types of transducers include variable-reluctance (or moving-armature, or electromagnetic) transducers, where magnetic force acts on

8436-511: The 20 natural crystal classes capable of piezoelectricity, and rigorously defined the piezoelectric constants using tensor analysis . The first practical application for piezoelectric devices was sonar , first developed during World War I . The superior performance of piezoelectric devices, operating at ultrasonic frequencies, superseded the earlier Fessenden oscillator . In France in 1917, Paul Langevin and his coworkers developed an ultrasonic submarine detector. The detector consisted of

8584-408: The 32 crystal classes , 21 are non- centrosymmetric (not having a centre of symmetry), and of these, 20 exhibit direct piezoelectricity (the 21st is the cubic class 432). Ten of these represent the polar crystal classes, which show a spontaneous polarization without mechanical stress due to a non-vanishing electric dipole moment associated with their unit cell, and which exhibit pyroelectricity . If

8732-462: The Admiralty archives. By 1918, Britain and France had built prototype active systems. The British tested their ASDIC on HMS  Antrim in 1920 and started production in 1922. The 6th Destroyer Flotilla had ASDIC-equipped vessels in 1923. An anti-submarine school HMS Osprey and a training flotilla of four vessels were established on Portland in 1924. By the outbreak of World War II ,

8880-700: The British Board of Invention and Research , Canadian physicist Robert William Boyle took on the active sound detection project with A. B. Wood , producing a prototype for testing in mid-1917. This work for the Anti-Submarine Division of the British Naval Staff was undertaken in utmost secrecy, and used quartz piezoelectric crystals to produce the world's first practical underwater active sound detection apparatus. To maintain secrecy, no mention of sound experimentation or quartz

9028-660: The French physicist Paul Langevin , working with a Russian immigrant electrical engineer Constantin Chilowsky, worked on the development of active sound devices for detecting submarines in 1915. Although piezoelectric and magnetostrictive transducers later superseded the electrostatic transducers they used, this work influenced future designs. Lightweight sound-sensitive plastic film and fibre optics have been used for hydrophones, while Terfenol-D and lead magnesium niobate (PMN) have been developed for projectors. In 1916, under

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9176-627: The United States. Research on ASDIC and underwater sound was expanded in the UK and in the US. Many new types of military sound detection were developed. These included sonobuoys , first developed by the British in 1944 under the codename High Tea , dipping/dunking sonar and mine -detection sonar. This work formed the basis for post-war developments related to countering the nuclear submarine . During

9324-425: The above equations are the most used form in literature, some comments about the notation are necessary. Generally, D and E are vectors , that is, Cartesian tensors of rank 1; and permittivity ε is a Cartesian tensor of rank 2. Strain and stress are, in principle, also rank-2 tensors . But conventionally, because strain and stress are all symmetric tensors, the subscript of strain and stress can be relabeled in

9472-404: The additional property, polarization , which is not a characteristic of longitudinal sound waves. The speed of sound depends on the medium the waves pass through, and is a fundamental property of the material. The first significant effort towards measurement of the speed of sound was made by Isaac Newton . He believed the speed of sound in a particular substance was equal to the square root of

9620-425: The advances in materials and the maturation of manufacturing processes, the United States market did not grow as quickly as Japan's did. Without many new applications, the growth of the United States' piezoelectric industry suffered. In contrast, Japanese manufacturers shared their information, quickly overcoming technical and manufacturing challenges and creating new markets. In Japan, a temperature stable crystal cut

9768-415: The area near the boat. When active sonar is used to measure the distance from the transducer to the bottom, it is known as echo sounding . Similar methods may be used looking upward for wave measurement. Active sonar is also used to measure distance through water between two sonar transducers or a combination of a hydrophone (underwater acoustic microphone) and projector (underwater acoustic speaker). When

9916-501: The attack had the advantage that the German acoustic torpedo was not effective against a warship travelling so slowly. A variation of the creeping attack was the "plaster" attack, in which three attacking ships working in a close line abreast were directed over the target by the directing ship. The new weapons to deal with the ASDIC blind spot were "ahead-throwing weapons", such as Hedgehogs and later Squids , which projected warheads at

10064-406: The basis for scanning probe microscopes that resolve images at the scale of atoms . It is used in the pickups of some electronically amplified guitars and as triggers in most modern electronic drums . The piezoelectric effect also finds everyday uses, such as generating sparks to ignite gas cooking and heating devices, torches, and cigarette lighters . The pyroelectric effect , by which

10212-512: The basis of all sound waves. They can be used to describe, in absolute terms, every sound we hear. In order to understand the sound more fully, a complex wave such as the one shown in a blue background on the right of this text, is usually separated into its component parts, which are a combination of various sound wave frequencies (and noise). Sound waves are often simplified to a description in terms of sinusoidal plane waves , which are characterized by these generic properties: Sound that

10360-510: The beam pattern suffered. Barium titanate was then replaced with more stable lead zirconate titanate (PZT), and the frequency was lowered to 5 kHz. The US fleet used this material in the AN/SQS-23 sonar for several decades. The SQS-23 sonar first used magnetostrictive nickel transducers, but these weighed several tons, and nickel was expensive and considered a critical material; piezoelectric transducers were therefore substituted. The sonar

10508-468: The bearing of the iceberg due to the 3-metre wavelength and the small dimension of the transducer's radiating face (less than 1 ⁄ 3 wavelength in diameter). The ten Montreal -built British H-class submarines launched in 1915 were equipped with Fessenden oscillators. During World War I the need to detect submarines prompted more research into the use of sound. The British made early use of underwater listening devices called hydrophones , while

10656-458: The bulk. For example, a 1 cm cube of quartz with 2 kN (500 lbf) of correctly applied force can produce a voltage of 12500 V . Piezoelectric materials also show the opposite effect, called the converse piezoelectric effect , where the application of an electrical field creates mechanical deformation in the crystal. Linear piezoelectricity is the combined effect of These may be combined into so-called coupled equations , of which

10804-456: The challenge of maintaining the performance and stability of their lead-based counterparts. In general, the main fabrication challenge is creating the "morphotropic phase boundaries (MPBs)" that provide the materials with their stable piezoelectric properties without introducing the "polymorphic phase boundaries (PPBs)" that decrease the temperature stability of the material. New phase boundaries are created by varying additive concentrations so that

10952-444: The characteristics of the outgoing ping. For these reasons, active sonar is not frequently used by military submarines. A very directional, but low-efficiency, type of sonar (used by fisheries, military, and for port security) makes use of a complex nonlinear feature of water known as non-linear sonar, the virtual transducer being known as a parametric array . Project Artemis was an experimental research and development project in

11100-434: The depth charges had been released, the attacking ship left the immediate area at full speed. The directing ship then entered the target area and also released a pattern of depth charges. The low speed of the approach meant the submarine could not predict when depth charges were going to be released. Any evasive action was detected by the directing ship and steering orders to the attacking ship given accordingly. The low speed of

11248-421: The dipole moment can be reversed by applying an external electric field, the material is said to be ferroelectric . For polar crystals, for which P  ≠ 0 holds without applying a mechanical load, the piezoelectric effect manifests itself by changing the magnitude or the direction of P or both. For the nonpolar but piezoelectric crystals, on the other hand, a polarization P different from zero

11396-408: The dipole moments per volume of the crystallographic unit cell . As every dipole is a vector, the dipole density P is a vector field . Dipoles near each other tend to be aligned in regions called Weiss domains. The domains are usually randomly oriented, but can be aligned using the process of poling (not the same as magnetic poling ), a process by which a strong electric field is applied across

11544-411: The duration of theta wave cycles. This means that at short durations, a very short sound can sound softer than a longer sound even though they are presented at the same intensity level. Past around 200 ms this is no longer the case and the duration of the sound no longer affects the apparent loudness of the sound. Timbre is perceived as the quality of different sounds (e.g. the thud of a fallen rock,

11692-411: The echoes. Since the original signal is much more powerful, it can be detected many times further than twice the range of the sonar (as in the example). Active sonar have two performance limitations: due to noise and reverberation. In general, one or other of these will dominate, so that the two effects can be initially considered separately. In noise-limited conditions at initial detection: where SL

11840-461: The electro-acoustic transducers are of the Tonpilz type and their design may be optimised to achieve maximum efficiency over the widest bandwidth, in order to optimise performance of the overall system. Occasionally, the acoustic pulse may be created by other means, e.g. chemically using explosives, airguns or plasma sound sources. To measure the distance to an object, the time from transmission of

11988-423: The entire signal is reflected from a 10 m target, it will be at 0.001 W/m when it reaches the emitter, i.e. just detectable. However, the original signal will remain above 0.001 W/m until 3000 m. Any 10 m target between 100 and 3000 m using a similar or better system would be able to detect the pulse, but would not be detected by the emitter. The detectors must be very sensitive to pick up

12136-401: The equation c = γ ⋅ p / ρ {\displaystyle c={\sqrt {\gamma \cdot p/\rho }}} . Since K = γ ⋅ p {\displaystyle K=\gamma \cdot p} , the final equation came up to be c = K / ρ {\displaystyle c={\sqrt {K/\rho }}} , which

12284-439: The extra compression (in case of longitudinal waves) or lateral displacement strain (in case of transverse waves) of the matter, and the kinetic energy of the displacement velocity of particles of the medium. Although there are many complexities relating to the transmission of sounds, at the point of reception (i.e. the ears), sound is readily dividable into two simple elements: pressure and time. These fundamental elements form

12432-406: The fastest in solid atomic hydrogen at about 36,000 m/s (129,600 km/h; 80,530 mph). Sound pressure is the difference, in a given medium, between average local pressure and the pressure in the sound wave. A square of this difference (i.e., a square of the deviation from the equilibrium pressure) is usually averaged over time and/or space, and a square root of this average provides

12580-492: The first piezoelectric liquid. Direct piezoelectricity of some substances, like quartz, can generate potential differences of thousands of volts. The principle of operation of a piezoelectric sensor is that a physical dimension, transformed into a force, acts on two opposing faces of the sensing element. Depending on the design of a sensor, different "modes" to load the piezoelectric element can be used: longitudinal, transversal and shear. Detection of pressure variations in

12728-421: The following fashion: 11 → 1; 22 → 2; 33 → 3; 23 → 4; 13 → 5; 12 → 6. (Different conventions may be used by different authors in literature. For example, some use 12 → 4; 23 → 5; 31 → 6 instead.) That is why S and T appear to have the "vector form" of six components. Consequently, s appears to be a 6-by-6 matrix instead of

12876-513: The form of sound is the most common sensor application, e.g. piezoelectric microphones (sound waves bend the piezoelectric material, creating a changing voltage) and piezoelectric pickups for acoustic-electric guitars . A piezo sensor attached to the body of an instrument is known as a contact microphone . Piezoelectric sensors especially are used with high frequency sound in ultrasonic transducers for medical imaging and also industrial nondestructive testing (NDT). For many sensing techniques,

13024-504: The government as a technical expert, first at the experimental station at Nahant, Massachusetts , and later at US Naval Headquarters, in London , England. At Nahant he applied the newly developed vacuum tube , then associated with the formative stages of the field of applied science now known as electronics , to the detection of underwater signals. As a result, the carbon button microphone , which had been used in earlier detection equipment,

13172-481: The hearing mechanism that results in the perception of sound. In this case, sound is a sensation . Acoustics is the interdisciplinary science that deals with the study of mechanical waves in gasses, liquids, and solids including vibration , sound, ultrasound, and infrasound. A scientist who works in the field of acoustics is an acoustician , while someone working in the field of acoustical engineering may be called an acoustical engineer . An audio engineer , on

13320-426: The information for timbre identification. Even though a small section of the wave form from each instrument looks very similar, differences in changes over time between the clarinet and the piano are evident in both loudness and harmonic content. Less noticeable are the different noises heard, such as air hisses for the clarinet and hammer strikes for the piano. Sonic texture relates to the number of sound sources and

13468-440: The interaction between them. The word texture , in this context, relates to the cognitive separation of auditory objects. In music, texture is often referred to as the difference between unison , polyphony and homophony , but it can also relate (for example) to a busy cafe; a sound which might be referred to as cacophony . Spatial location represents the cognitive placement of a sound in an environmental context; including

13616-505: The largest individual sonar transducers ever. The advantage of metals is their high tensile strength and low input electrical impedance, but they have electrical losses and lower coupling coefficient than PZT, whose tensile strength can be increased by prestressing . Other materials were also tried; nonmetallic ferrites were promising for their low electrical conductivity resulting in low eddy current losses, Metglas offered high coupling coefficient, but they were inferior to PZT overall. In

13764-496: The late 1950s to mid 1960s to examine acoustic propagation and signal processing for a low-frequency active sonar system that might be used for ocean surveillance. A secondary objective was examination of engineering problems of fixed active bottom systems. The receiving array was located on the slope of Plantagnet Bank off Bermuda. The active source array was deployed from the converted World War II tanker USNS  Mission Capistrano . Elements of Artemis were used experimentally after

13912-404: The magnetostrictive unit was much more reliable. High losses to US merchant supply shipping early in World War II led to large scale high priority US research in the field, pursuing both improvements in magnetostrictive transducer parameters and Rochelle salt reliability. Ammonium dihydrogen phosphate (ADP), a superior alternative, was found as a replacement for Rochelle salt; the first application

14060-416: The main experiment was terminated. This is an active sonar device that receives a specific stimulus and immediately (or with a delay) retransmits the received signal or a predetermined one. Transponders can be used to remotely activate or recover subsea equipment. A sonar target is small relative to the sphere , centred around the emitter, on which it is located. Therefore, the power of the reflected signal

14208-436: The material, usually at elevated temperatures. Not all piezoelectric materials can be poled. Of decisive importance for the piezoelectric effect is the change of polarization P when applying a mechanical stress . This might either be caused by a reconfiguration of the dipole-inducing surrounding or by re-orientation of molecular dipole moments under the influence of the external stress. Piezoelectricity may then manifest in

14356-403: The moments leading up to attack. The hunter was effectively firing blind, during which time a submarine commander could take evasive action. This situation was remedied with new tactics and new weapons. The tactical improvements developed by Frederic John Walker included the creeping attack. Two anti-submarine ships were needed for this (usually sloops or corvettes). The "directing ship" tracked

14504-439: The most piezoelectricity. The Curies, however, did not predict the converse piezoelectric effect. The converse effect was mathematically deduced from fundamental thermodynamic principles by Gabriel Lippmann in 1881. The Curies immediately confirmed the existence of the converse effect, and went on to obtain quantitative proof of the complete reversibility of electro-elasto-mechanical deformations in piezoelectric crystals. For

14652-432: The next few decades, piezoelectricity remained something of a laboratory curiosity, though it was a vital tool in the discovery of polonium and radium by Pierre and Marie Curie in 1898. More work was done to explore and define the crystal structures that exhibited piezoelectricity. This culminated in 1910 with the publication of Woldemar Voigt 's Lehrbuch der Kristallphysik ( Textbook on Crystal Physics ), which described

14800-492: The ocean or floats on a taut line mooring at a constant depth of perhaps 100 m. They may also be used by submarines , AUVs , and floats such as the Argo float. Passive sonar listens without transmitting. It is often employed in military settings, although it is also used in science applications, e.g. , detecting fish for presence/absence studies in various aquatic environments – see also passive acoustics and passive radar . In

14948-461: The offset messages are missed owing to disruptions from noises in the same general bandwidth. This can be of great benefit in understanding distorted messages such as radio signals that suffer from interference, as (owing to this effect) the message is heard as if it was continuous. Loudness is perceived as how "loud" or "soft" a sound is and relates to the totalled number of auditory nerve stimulations over short cyclic time periods, most likely over

15096-401: The other factors are as before. An upward looking sonar (ULS) is a sonar device pointed upwards looking towards the surface of the sea. It is used for similar purposes as downward looking sonar, but has some unique applications such as measuring sea ice thickness, roughness and concentration, or measuring air entrainment from bubble plumes during rough seas. Often it is moored on the bottom of

15244-482: The other hand, is concerned with the recording, manipulation, mixing, and reproduction of sound. Applications of acoustics are found in almost all aspects of modern society, subdisciplines include aeroacoustics , audio signal processing , architectural acoustics , bioacoustics , electro-acoustics, environmental noise , musical acoustics , noise control , psychoacoustics , speech , ultrasound , underwater acoustics , and vibration . Sound can propagate through

15392-609: The piezoelectric performance in such systems and should be avoided, as the microstructure in piezoceramics exhibiting AGG tends to consist of few abnormally large elongated grains in a matrix of randomly oriented finer grains. Macroscopic piezoelectricity is possible in textured polycrystalline non-ferroelectric piezoelectric materials, such as AlN and ZnO. The families of ceramics with perovskite , tungsten - bronze , and related structures exhibit piezoelectricity: The fabrication of lead-free piezoceramics pose multiple challenges, from an environmental standpoint and their ability to replicate

15540-580: The placement of a sound on both the horizontal and vertical plane, the distance from the sound source and the characteristics of the sonic environment. In a thick texture, it is possible to identify multiple sound sources using a combination of spatial location and timbre identification. Ultrasound is sound waves with frequencies higher than 20,000 Hz. Ultrasound is not different from audible sound in its physical properties, but cannot be heard by humans. Ultrasound devices operate with frequencies from 20 kHz up to several gigahertz. Medical ultrasound

15688-509: The pressure acting on it divided by its density: This was later proven wrong and the French mathematician Laplace corrected the formula by deducing that the phenomenon of sound travelling is not isothermal, as believed by Newton, but adiabatic . He added another factor to the equation— gamma —and multiplied γ {\displaystyle {\sqrt {\gamma }}} by p / ρ {\displaystyle {\sqrt {p/\rho }}} , thus coming up with

15836-477: The production of ultrasound waves . French physicists Jacques and Pierre Curie discovered piezoelectricity in 1880. The piezoelectric effect has been exploited in many useful applications, including the production and detection of sound, piezoelectric inkjet printing , generation of high voltage electricity, as a clock generator in electronic devices, in microbalances , to drive an ultrasonic nozzle , and in ultrafine focusing of optical assemblies. It forms

15984-423: The production of harmonics and mixed tones not present in the original sound (see parametric array ). If relativistic effects are important, the speed of sound is calculated from the relativistic Euler equations . In fresh water the speed of sound is approximately 1,482 m/s (5,335 km/h; 3,315 mph). In steel, the speed of sound is about 5,960 m/s (21,460 km/h; 13,330 mph). Sound moves

16132-402: The projectors consisted of two rectangular identical independent units in a cast-iron rectangular body about 16 by 9 inches (410 mm × 230 mm). The exposed area was half the wavelength wide and three wavelengths high. The magnetostrictive cores were made from 4 mm stampings of nickel, and later of an iron-aluminium alloy with aluminium content between 12.7% and 12.9%. The power

16280-493: The properties of their lead-based counterparts. By removing the lead component of the piezoceramic, the risk of toxicity to humans decreases, but the mining and extraction of the materials can be harmful to the environment. Analysis of the environmental profile of PZT versus sodium potassium niobate (NKN or KNN) shows that across the four indicators considered (primary energy consumption, toxicological footprint, eco-indicator 99, and input-output upstream greenhouse gas emissions), KNN

16428-409: The pulse. This pulse of sound is generally created electronically using a sonar projector consisting of a signal generator, power amplifier and electro-acoustic transducer/array. A transducer is a device that can transmit and receive acoustic signals ("pings"). A beamformer is usually employed to concentrate the acoustic power into a beam, which may be swept to cover the required search angles. Generally,

16576-555: The question: " if a tree falls in a forest and no one is around to hear it, does it make a sound? " is "yes", and "no", dependent on whether being answered using the physical, or the psychophysical definition, respectively. The physical reception of sound in any hearing organism is limited to a range of frequencies. Humans normally hear sound frequencies between approximately 20  Hz and 20,000 Hz (20  kHz ), The upper limit decreases with age. Sometimes sound refers to only those vibrations with frequencies that are within

16724-456: The radial speed of the searching platform. One useful small sonar is similar in appearance to a waterproof flashlight. The head is pointed into the water, a button is pressed, and the device displays the distance to the target. Another variant is a " fishfinder " that shows a small display with shoals of fish. Some civilian sonars (which are not designed for stealth) approach active military sonars in capability, with three-dimensional displays of

16872-443: The response of the human ear to noise and A-weighted sound pressure levels are labeled dBA. C-weighting is used to measure peak levels. A distinct use of the term sound from its use in physics is that in physiology and psychology, where the term refers to the subject of perception by the brain. The field of psychoacoustics is dedicated to such studies. Webster's dictionary defined sound as: "1. The sensation of hearing, that which

17020-585: The second set of four terms corresponds to the converse piezoelectric effect. The equality between the direct piezoelectric tensor and the transpose of the converse piezoelectric tensor originates from the Maxwell relations of thermodynamics. For those piezoelectric crystals for which the polarization is of the crystal-field induced type, a formalism has been worked out that allows for the calculation of piezoelectrical coefficients d ij from electrostatic lattice constants or higher-order Madelung constants . Of

17168-594: The sensor can act as both a sensor and an actuator—often the term transducer is preferred when the device acts in this dual capacity, but most piezo devices have this property of reversibility whether it is used or not. Ultrasonic transducers, for example, can inject ultrasound waves into the body, receive the returned wave, and convert it to an electrical signal (a voltage). Most medical ultrasound transducers are piezoelectric. In addition to those mentioned above, various sensor and transducer applications include: As very high electric fields correspond to only tiny changes in

17316-428: The sonar operator usually finally classifies the signals manually. A computer system frequently uses these databases to identify classes of ships, actions (i.e. the speed of a ship, or the type of weapon released and the most effective countermeasures to employ), and even particular ships. Sound In physics , sound is a vibration that propagates as an acoustic wave through a transmission medium such as

17464-528: The sound is called the medium . Sound cannot travel through a vacuum . Studies has shown that sound waves are able to carry a tiny amount of mass and is surrounded by a weak gravitational field. Sound is transmitted through gases, plasma, and liquids as longitudinal waves , also called compression waves. It requires a medium to propagate. Through solids, however, it can be transmitted as both longitudinal waves and transverse waves . Longitudinal sound waves are waves of alternating pressure deviations from

17612-441: The sound made by vessels; active sonar means emitting pulses of sounds and listening for echoes. Sonar may be used as a means of acoustic location and of measurement of the echo characteristics of "targets" in the water. Acoustic location in air was used before the introduction of radar . Sonar may also be used for robot navigation, and sodar (an upward-looking in-air sonar) is used for atmospheric investigations. The term sonar

17760-420: The sound wave. At a fixed distance from the source, the pressure , velocity , and displacement of the medium vary in time. At an instant in time, the pressure, velocity, and displacement vary in space. The particles of the medium do not travel with the sound wave. This is intuitively obvious for a solid, and the same is true for liquids and gases (that is, the vibrations of particles in the gas or liquid transport

17908-417: The speed of sound in gases depends on temperature. In 20 °C (68 °F) air at sea level, the speed of sound is approximately 343 m/s (1,230 km/h; 767 mph) using the formula v  [m/s] = 331 + 0.6  T  [°C] . The speed of sound is also slightly sensitive, being subject to a second-order anharmonic effect, to the sound amplitude, which means there are non-linear propagation effects, such as

18056-448: The strongest piezoelectricity is observed are those commonly found in the wurtzite structure, i.e. GaN , InN , AlN and ZnO (see piezotronics ). Since 2006, there have also been a number of reports of strong non linear piezoelectric effects in polar semiconductors . Such effects are generally recognized to be at least important if not of the same order of magnitude as the first order approximation. The piezo-response of polymers

18204-436: The surfaces of gaps, and moving coil (or electrodynamic) transducers, similar to conventional speakers; the latter are used in underwater sound calibration, due to their very low resonance frequencies and flat broadband characteristics above them. Active sonar uses a sound transmitter (or projector) and a receiver. When the two are in the same place it is monostatic operation . When the transmitter and receiver are separated it

18352-600: The target and localise it, as well as measuring its velocity. The pulse may be at constant frequency or a chirp of changing frequency (to allow pulse compression on reception). Simple sonars generally use the former with a filter wide enough to cover possible Doppler changes due to target movement, while more complex ones generally include the latter technique. Since digital processing became available pulse compression has usually been implemented using digital correlation techniques. Military sonars often have multiple beams to provide all-round cover while simple ones only cover

18500-405: The target submarine on ASDIC from a position about 1500 to 2000 yards behind the submarine. The second ship, with her ASDIC turned off and running at 5 knots, started an attack from a position between the directing ship and the target. This attack was controlled by radio telephone from the directing ship, based on their ASDIC and the range (by rangefinder) and bearing of the attacking ship. As soon as

18648-458: The torpedo went after the noisier fizzy decoy. The counter-countermeasure was a torpedo with active sonar – a transducer was added to the torpedo nose, and the microphones were listening for its reflected periodic tone bursts. The transducers comprised identical rectangular crystal plates arranged to diamond-shaped areas in staggered rows. Passive sonar arrays for submarines were developed from ADP crystals. Several crystal assemblies were arranged in

18796-409: The two platforms. This technique, when used with multiple transducers/hydrophones/projectors, can calculate the relative positions of static and moving objects in water. In combat situations, an active pulse can be detected by an enemy and will reveal a submarine's position at twice the maximum distance that the submarine can itself detect a contact and give clues as to the submarine's identity based on

18944-430: The ultrasonic transducer allowed for easy measurement of viscosity and elasticity in fluids and solids, resulting in huge advances in materials research. Ultrasonic time-domain reflectometers (which send an ultrasonic pulse through a material and measure reflections from discontinuities) could find flaws inside cast metal and stone objects, improving structural safety. During World War II , independent research groups in

19092-446: The use of aviation radio. Development of piezoelectric devices and materials in the United States was kept within the companies doing the development, mostly due to the wartime beginnings of the field, and in the interests of securing profitable patents. New materials were the first to be developed—quartz crystals were the first commercially exploited piezoelectric material, but scientists searched for higher-performance materials. Despite

19240-422: The value of the corresponding tensor shear, such as S 6  = 2 S 12 and so on. This also means that s 66  =  ⁠ 1 / G 12 ⁠ , where G 12 is the shear modulus. In total, there are four piezoelectric coefficients, d ij , e ij , g ij , and h ij defined as follows: where the first set of four terms corresponds to the direct piezoelectric effect and

19388-481: The very broadest usage, this term can encompass virtually any analytical technique involving remotely generated sound, though it is usually restricted to techniques applied in an aquatic environment. Passive sonar has a wide variety of techniques for identifying the source of a detected sound. For example, U.S. vessels usually operate 60 Hertz (Hz) alternating current power systems. If transformers or generators are mounted without proper vibration insulation from

19536-566: The vibrations, while the average position of the particles over time does not change). During propagation, waves can be reflected , refracted , or attenuated by the medium. The behavior of sound propagation is generally affected by three things: When sound is moving through a medium that does not have constant physical properties, it may be refracted (either dispersed or focused). The mechanical vibrations that can be interpreted as sound can travel through all forms of matter : gases, liquids, solids, and plasmas . The matter that supports

19684-434: The water was initially recorded by Leonardo da Vinci in 1490: a tube inserted into the water was said to be used to detect vessels by placing an ear to the tube. In the late 19th century, an underwater bell was used as an ancillary to lighthouses or lightships to provide warning of hazards. The use of sound to "echo-locate" underwater in the same way as bats use sound for aerial navigation seems to have been prompted by

19832-430: The whir of a drill, the tone of a musical instrument or the quality of a voice) and represents the pre-conscious allocation of a sonic identity to a sound (e.g. "it's an oboe!"). This identity is based on information gained from frequency transients, noisiness, unsteadiness, perceived pitch and the spread and intensity of overtones in the sound over an extended time frame. The way a sound changes over time provides most of

19980-484: The width of the crystal, this width can be changed with better-than- μm precision, making piezo crystals the most important tool for positioning objects with extreme accuracy—thus their use in actuators . Multilayer ceramics, using layers thinner than 100 μm , allow reaching high electric fields with voltage lower than 150 V . These ceramics are used within two kinds of actuators: direct piezo actuators and amplified piezoelectric actuators . While direct actuator's stroke

20128-465: Was a large array of 432 individual transducers. At first, the transducers were unreliable, showing mechanical and electrical failures and deteriorating soon after installation; they were also produced by several vendors, had different designs, and their characteristics were different enough to impair the array's performance. The policy to allow repair of individual transducers was then sacrificed, and "expendable modular design", sealed non-repairable modules,

20276-559: Was a replacement of the 24 kHz Rochelle-salt transducers. Within nine months, Rochelle salt was obsolete. The ADP manufacturing facility grew from few dozen personnel in early 1940 to several thousands in 1942. One of the earliest application of ADP crystals were hydrophones for acoustic mines ; the crystals were specified for low-frequency cutoff at 5 Hz, withstanding mechanical shock for deployment from aircraft from 3,000 m (10,000 ft), and ability to survive neighbouring mine explosions. One of key features of ADP reliability

20424-543: Was being loaded on the cable-laying vessel, World War I ended and Horton returned home. During World War II, he continued to develop sonar systems that could detect submarines, mines, and torpedoes. He published Fundamentals of Sonar in 1957 as chief research consultant at the US Navy Underwater Sound Laboratory . He held this position until 1959 when he became technical director, a position he held until mandatory retirement in 1963. There

20572-668: Was chosen instead, eliminating the problem with seals and other extraneous mechanical parts. The Imperial Japanese Navy at the onset of World War II used projectors based on quartz . These were big and heavy, especially if designed for lower frequencies; the one for Type 91 set, operating at 9 kHz, had a diameter of 30 inches (760 mm) and was driven by an oscillator with 5 kW power and 7 kV of output amplitude. The Type 93 projectors consisted of solid sandwiches of quartz, assembled into spherical cast iron bodies. The Type 93 sonars were later replaced with Type 3, which followed German design and used magnetostrictive projectors;

20720-441: Was developed by Bell Telephone Laboratories . Following World War I, Frederick R. Lack, working in radio telephony in the engineering department, developed the "AT cut" crystal, a crystal that operated through a wide range of temperatures. Lack's crystal did not need the heavy accessories previous crystal used, facilitating its use on the aircraft. This development allowed Allied air forces to engage in coordinated mass attacks through

20868-516: Was developed by Issac Koga . Japanese efforts in materials research created piezoceramic materials competitive to the United States materials but free of expensive patent restrictions. Major Japanese piezoelectric developments included new designs of piezoceramic filters for radios and televisions, piezo buzzers and audio transducers that can connect directly to electronic circuits, and the piezoelectric igniter , which generates sparks for small engine ignition systems and gas-grill lighters, by compressing

21016-434: Was developed during World War I to counter the growing threat of submarine warfare , with an operational passive sonar system in use by 1918. Modern active sonar systems use an acoustic transducer to generate a sound wave which is reflected from target objects. Although some animals ( dolphins , bats , some shrews , and others) have used sound for communication and object detection for millions of years, use by humans in

21164-432: Was in 1880 by the brothers Pierre Curie and Jacques Curie . They combined their knowledge of pyroelectricity with their understanding of the underlying crystal structures that gave rise to pyroelectricity to predict crystal behavior, and demonstrated the effect using crystals of tourmaline , quartz , topaz , cane sugar , and Rochelle salt (sodium potassium tartrate tetrahydrate). Quartz and Rochelle salt exhibited

21312-426: Was little progress in US sonar from 1915 to 1940. In 1940, US sonars typically consisted of a magnetostrictive transducer and an array of nickel tubes connected to a 1-foot-diameter steel plate attached back-to-back to a Rochelle salt crystal in a spherical housing. This assembly penetrated the ship hull and was manually rotated to the desired angle. The piezoelectric Rochelle salt crystal had better parameters, but

21460-608: Was made – the word used to describe the early work ("supersonics") was changed to "ASD"ics, and the quartz material to "ASD"ivite: "ASD" for "Anti-Submarine Division", hence the British acronym ASDIC . In 1939, in response to a question from the Oxford English Dictionary , the Admiralty made up the story that it stood for "Allied Submarine Detection Investigation Committee", and this is still widely believed, though no committee bearing this name has been found in

21608-576: Was provided from a 2 kW at 3.8 kV, with polarization from a 20 V, 8 A DC source. The passive hydrophones of the Imperial Japanese Navy were based on moving-coil design, Rochelle salt piezo transducers, and carbon microphones . Magnetostrictive transducers were pursued after World War II as an alternative to piezoelectric ones. Nickel scroll-wound ring transducers were used for high-power low-frequency operations, with size up to 13 feet (4.0 m) in diameter, probably

21756-512: Was replaced by the precursor of the modern hydrophone . Also during this period, he experimented with methods for towing detection. This was due to the increased sensitivity of his device. The principles are still used in modern towed sonar systems. To meet the defense needs of Great Britain, he was sent to England to install in the Irish Sea bottom-mounted hydrophones connected to a shore listening post by submarine cable. While this equipment

21904-1082: Was reported by Zhu et al. that a piezoelectric response of about 17 pC/N could be obtained from PDMS/PZT nanocomposite at 60% porosity. Another PDMS nanocomposite was reported in 2017, in which BaTiO 3 was integrated into PDMS to make a stretchable, transparent nanogenerator for self-powered physiological monitoring. In 2016, polar molecules were introduced into a polyurethane foam in which high responses of up to 244 pC/N were reported. Most materials exhibit at least weak piezoelectric responses. Trivial examples include sucrose (table sugar), DNA , viral proteins, including those from bacteriophage . An actuator based on wood fibers, called cellulose fibers , has been reported. D33 responses for cellular polypropylene are around 200 pC/N. Some applications of cellular polypropylene are musical key pads, microphones, and ultrasound-based echolocation systems. Recently, single amino acid such as β-glycine also displayed high piezoelectric (178 pmV ) as compared to other biological materials. Ionic liquids were recently identified as

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