Acoustic locationAcoustic location is the use of sound to determine the distance and direction of its source or reflector. Location can be done actively or passively, and can take place in gases (such as the atmosphere), liquids (such as water), and in solids (such as in the earth). Active acoustic location involves the creation of sound in order to produce an echo, which is then analyzed to determine the location of the object in question.
Fatigue (material)In materials science, fatigue is the initiation and propagation of cracks in a material due to cyclic loading. Once a fatigue crack has initiated, it grows a small amount with each loading cycle, typically producing striations on some parts of the fracture surface. The crack will continue to grow until it reaches a critical size, which occurs when the stress intensity factor of the crack exceeds the fracture toughness of the material, producing rapid propagation and typically complete fracture of the structure.
SonarSonar (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 the sound made by vessels; active sonar means emitting pulses of sounds and listening for echoes.
FrackingFracking (also known as hydraulic fracturing, fracing, hydrofracturing, or hydrofracking) is a well stimulation technique involving the fracturing of bedrock formations by a pressurized liquid. The process involves the high-pressure injection of "fracking fluid" (primarily water, containing sand or other proppants suspended with the aid of thickening agents) into a wellbore to create cracks in the deep-rock formations through which natural gas, petroleum, and brine will flow more freely.
Underwater acousticsUnderwater acoustics or hydroacoustics is the study of the propagation of sound in water and the interaction of the mechanical waves that constitute sound with the water, its contents and its boundaries. The water may be in the ocean, a lake, a river or a tank. Typical frequencies associated with underwater acoustics are between 10 Hz and 1 MHz. The propagation of sound in the ocean at frequencies lower than 10 Hz is usually not possible without penetrating deep into the seabed, whereas frequencies above 1 MHz are rarely used because they are absorbed very quickly.
AcousticsAcoustics is a branch of physics that deals with the study of mechanical waves in gases, liquids, and solids including topics such as vibration, sound, ultrasound and infrasound. A scientist who works in the field of acoustics is an acoustician while someone working in the field of acoustics technology may be called an acoustical engineer. The application of acoustics is present in almost all aspects of modern society with the most obvious being the audio and noise control industries.
Studio monitorStudio monitors are loudspeakers in speaker enclosures specifically designed for professional audio production applications, such as recording studios, filmmaking, television studios, radio studios and project or home studios, where accurate audio reproduction is crucial. Among audio engineers, the term monitor implies that the speaker is designed to produce relatively flat (linear) phase and frequency responses.
Shale gasShale gas is an unconventional natural gas that is found trapped within shale formations. Since the 1990s a combination of horizontal drilling and hydraulic fracturing has made large volumes of shale gas more economical to produce, and some analysts expect that shale gas will greatly expand worldwide energy supply. Shale gas has become an increasingly important source of natural gas in the United States since the start of this century, and interest has spread to potential gas shales in the rest of the world.
Active noise controlActive noise control (ANC), also known as noise cancellation (NC), or active noise reduction (ANR), is a method for reducing unwanted sound by the addition of a second sound specifically designed to cancel the first. The concept was first developed in the late 1930s; later developmental work that began in the 1950s eventually resulted in commercial airline headsets with the technology becoming available in the late 1980s. The technology is also used in road vehicles, mobile telephones, earbuds, and headphones.
Surface acoustic waveA surface acoustic wave (SAW) is an acoustic wave traveling along the surface of a material exhibiting elasticity, with an amplitude that typically decays exponentially with depth into the material, such that they are confined to a depth of about one wavelength. SAWs were first explained in 1885 by Lord Rayleigh, who described the surface acoustic mode of propagation and predicted its properties in his classic paper. Named after their discoverer, Rayleigh waves have a longitudinal and a vertical shear component that can couple with any media like additional layers in contact with the surface.
Stage monitor systemA stage monitor system is a set of performer-facing loudspeakers called monitor speakers, stage monitors, floor monitors, wedges, or foldbacks on stage during live music performances in which a sound reinforcement system is used to amplify a performance for the audience. The monitor system allows musicians to hear themselves and fellow band members clearly. The sound at popular music and rock music concerts is amplified with power amplifiers through a sound reinforcement system.
Natural gasNatural gas (also called fossil gas, methane gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbon dioxide, nitrogen, hydrogen sulfide, and helium are also usually present. Methane is colorless and odorless, and the second largest greenhouse gas contributor to global climate change after carbon dioxide.
Object co-segmentationIn computer vision, object co-segmentation is a special case of , which is defined as jointly segmenting semantically similar objects in multiple images or video frames. It is often challenging to extract segmentation masks of a target/object from a noisy collection of images or video frames, which involves object discovery coupled with . A noisy collection implies that the object/target is present sporadically in a set of images or the object/target disappears intermittently throughout the video of interest.
FractographyFractography is the study of the fracture surfaces of materials. Fractographic methods are routinely used to determine the cause of failure in engineering structures, especially in product failure and the practice of forensic engineering or failure analysis. In material science research, fractography is used to develop and evaluate theoretical models of crack growth behavior. One of the aims of fractographic examination is to determine the cause of failure by studying the characteristics of a fractured surface.
Environmental impact of frackingThe environmental impact of fracking is related to land use and water consumption, air emissions, including methane emissions, brine and fracturing fluid leakage, water contamination, noise pollution, and health. Water and air pollution are the biggest risks to human health from fracking. Research has determined that fracking negatively affects human health and drives climate change. Fracking fluids include proppants and other substances, which include chemicals known to be toxic, as well as unknown chemicals that may be toxic.
MicrophoneA microphone, colloquially called mic (maɪk), is a transducer that converts sound into an electrical signal. Microphones are used in many applications such as telephones, hearing aids, public address systems for concert halls and public events, motion picture production, live and recorded audio engineering, sound recording, two-way radios, megaphones, and radio and television broadcasting. They are also used in computers for recording voice, speech recognition, VoIP, and for other purposes such as ultrasonic sensors or knock sensors.
Acoustic signatureThe term acoustic signature is used to describe a combination of acoustic emissions of sound emitters, such as those of ships and submarines. In addition, aircraft, machinery, and living animals can be described as having their own characteristic acoustic signatures or sound attributes, which can be used to study their condition, behavior, and physical location. Acoustic homing and Acoustic torpedo The analysis of acoustic signatures is an important adjunct to passive sonar used to track naval warships and weapons.
Bone fractureA bone fracture (abbreviated FRX or Fx, Fx, or #) is a medical condition in which there is a partial or complete break in the continuity of any bone in the body. In more severe cases, the bone may be broken into several fragments, known as a comminuted fracture. A bone fracture may be the result of high force impact or stress, or a minimal trauma injury as a result of certain medical conditions that weaken the bones, such as osteoporosis, osteopenia, bone cancer, or osteogenesis imperfecta, where the fracture is then properly termed a pathologic fracture.
Hydrographic surveyHydrographic survey is the science of measurement and description of features which affect maritime navigation, marine construction, dredging, offshore oil exploration and drilling and related activities. Strong emphasis is placed on soundings, shorelines, tides, currents, seabed and submerged obstructions that relate to the previously mentioned activities. The term hydrography is used synonymously to describe maritime cartography, which in the final stages of the hydrographic process uses the raw data collected through hydrographic survey into information usable by the end user.
Blob detectionIn computer vision, blob detection methods are aimed at detecting regions in a that differ in properties, such as brightness or color, compared to surrounding regions. Informally, a blob is a region of an image in which some properties are constant or approximately constant; all the points in a blob can be considered in some sense to be similar to each other. The most common method for blob detection is convolution.
