1.
Saw
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A saw is a tool consisting of a tough blade, wire, or chain with a hard toothed edge. It is used to cut material, very often wood. The cut is made by placing the edge against the material and moving it forcefully forth. This force may be applied by hand, or powered by steam, water, an abrasive saw has a powered circular blade designed to cut through metal. Abrasive saw, A saw that cuts with a disc or band. Back, the edge opposite the toothed edge, fleam, The angle of the faces of the teeth relative to a line perpendicular to the face of the saw. Gullet, The valley between the points of the teeth, heel, The end closest to the handle. For example, a blade can cause excessive wobble, creating a wider-than-expected kerf. The kerf created by a blade can be changed by adjusting the set of its teeth with a tool called a saw tooth setter. Points per inch, The most common measurement of the frequency of teeth on a saw blade. It is taken by setting the tip of one tooth at the point on a ruler. There is always one point per inch than there are teeth per inch. Some saws do not have the number of teeth per inch throughout their entire length. Those with more teeth per inch at the toe are described as having incremental teeth, rake, The angle of the front face of the tooth relative to a line perpendicular to the length of the saw. In most modern serrated saws, the teeth are set, so that the kerf will be wider than the blade itself and this allows the blade to move through the cut easily without binding. The set may be different depending on the kind of cut the saw is intended to make, for example, a rip saw has a tooth set that is similar to the angle used on a chisel, so that it rips or tears the material apart. A flush-cutting saw has no set on one side, so that the saw can be flat on a surface. The set of the teeth can be adjusted with a tool called a saw set
2.
Additive synthesis
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Additive synthesis is a sound synthesis technique that creates timbre by adding sine waves together. The timbre of instruments can be considered in the light of Fourier theory to consist of multiple harmonic or inharmonic partials or overtones. Each partial is a wave of different frequency and amplitude that swells. Additive synthesis most directly generates sound by adding the output of multiple sine wave generators, alternative implementations may use pre-computed wavetables or the inverse Fast Fourier transform. These sinusoids are called harmonics, overtones, or generally, partials, in general, a Fourier series contains an infinite number of sinusoidal components, with no upper limit to the frequency of the sinusoidal functions and includes a DC component. Frequencies outside of the audible range can be omitted in additive synthesis. As a result, only a number of sinusoidal terms with frequencies that lie within the audible range are modeled in additive synthesis. A waveform or function is said to be periodic if y = y for all t, the bandwidth of r k should be significantly less than f 0. Additive synthesis can also produce sounds in which the individual overtones need not have frequencies that are integer multiples of some common fundamental frequency. While many conventional musical instruments have harmonic partials, some have inharmonic partials, inharmonic additive synthesis can be described as y = ∑ k =1 K r k cos , where f k is the constant frequency of k th partial. In the general case, the frequency of a sinusoid is the derivative of the argument of the sine or cosine function. If this frequency is represented in hertz, rather than in angular frequency form and this is the case whether the partial is harmonic or inharmonic and whether its frequency is constant or time-varying. For example, F. Richard Moore listed additive synthesis as one of the four categories of sound synthesis alongside subtractive synthesis, nonlinear synthesis. In this broad sense, pipe organs, which also have pipes producing non-sinusoidal waveforms, summation of principal components and Walsh functions have also been classified as additive synthesis. Modern-day implementations of additive synthesis are mainly digital, Additive synthesis can be implemented using a bank of sinusoidal oscillators, one for each partial. Group additive synthesis is a method to group partials into harmonic groups, an inverse Fast Fourier transform can be used to efficiently synthesize frequencies that evenly divide the transform period or frame. It is possible to analyze the components of a recorded sound giving a sum of sinusoids representation. This representation can be re-synthesized using additive synthesis, one method of decomposing a sound into time varying sinusoidal partials is short-time Fourier transform -based McAulay-Quatieri Analysis
3.
Switched-mode power supply
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A switched-mode power supply is an electronic power supply that incorporates a switching regulator to convert electrical power efficiently. Like other power supplies, an SMPS transfers power from a DC or AC source, to DC loads, such as a computer, while converting voltage. Ideally, a power supply dissipates no power. Voltage regulation is achieved by varying the ratio of on-to-off time, in contrast, a linear power supply regulates the output voltage by continually dissipating power in the pass transistor. This higher power efficiency is an important advantage of a switched-mode power supply. Switched-mode power supplies may also be smaller and lighter than a linear supply due to the smaller transformer size. Switching regulators are used as replacements for linear regulators when higher efficiency and they are, however, more complicated, their switching currents can cause electrical noise problems if not carefully suppressed, and simple designs may have a poor power factor. 1836 Induction coils use switches to generate high voltages,1910 An inductive discharge ignition system invented by Charles F. Kettering and his company Dayton Engineering Laboratories Company goes into production for Cadillac. The Kettering ignition system is a version of a flyback boost converter. Variations of this system were used in all non-diesel internal combustion engines until the 1960s when it was displaced with capacitive discharge ignition systems. 1926 On 23 June, British inventor Philip Ray Coursey applies for a patent in his country and United States, the patent mentions high frequency welding and furnaces, among other uses. Ca 1936 Car radios used electromechanical vibrators to transform the 6 V battery supply to a suitable B+ voltage for the vacuum tubes,1959 Transistor oscillation and rectifying converter power supply system U. S. 1972 HP-35, Hewlett-Packards first pocket calculator, is introduced with transistor switching power supply for light-emitting diodes, clocks, timing, ROM,1973 Xerox uses switching power supplies in the Alto minicomputer 1977 Apple II is designed with a switching mode power supply. Rod Holt was brought in as engineer and there were several flaws in Apple II that were never publicized. One thing Holt has to his credit is that he created the power supply that allowed us to do a very lightweight computer. 1980 The HP8662A10 kHz –1.28 GHz synthesized signal generator went with a switched mode power supply, a linear regulator provides the desired output voltage by dissipating excess power in ohmic losses. Ideal switching elements have no resistance when closed and carry no current when open and this is because the inductor responds to changes in current by inducing its own voltage to counter the change in current, and this voltage adds to the source voltage while the switch is open. This boost converter acts like a transformer for DC signals
4.
Cathode ray tube
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The cathode ray tube is a vacuum tube that contains one or more electron guns and a phosphorescent screen, and is used to display images. It modulates, accelerates, and deflects electron beam onto the screen to create the images, the images may represent electrical waveforms, pictures, radar targets, or others. CRTs have also used as memory devices, in which case the visible light emitted from the fluorescent material is not intended to have significant meaning to a visual observer. In television sets and computer monitors, the front area of the tube is scanned repetitively and systematically in a fixed pattern called a raster. An image is produced by controlling the intensity of each of the three beams, one for each additive primary color with a video signal as a reference. A CRT is constructed from an envelope which is large, deep, fairly heavy. The interior of a CRT is evacuated to approximately 0.01 Pa to 133 nPa. evacuation being necessary to facilitate the flight of electrons from the gun to the tubes face. That it is evacuated makes handling an intact CRT potentially dangerous due to the risk of breaking the tube and causing a violent implosion that can hurl shards of glass at great velocity. As a matter of safety, the face is made of thick lead glass so as to be highly shatter-resistant and to block most X-ray emissions. Flat panel displays can also be made in large sizes, whereas 38 to 40 was about the largest size of a CRT television, flat panels are available in 60. Cathode rays were discovered by Johann Hittorf in 1869 in primitive Crookes tubes and he observed that some unknown rays were emitted from the cathode which could cast shadows on the glowing wall of the tube, indicating the rays were traveling in straight lines. In 1890, Arthur Schuster demonstrated cathode rays could be deflected by electric fields, the earliest version of the CRT was known as the Braun tube, invented by the German physicist Ferdinand Braun in 1897. It was a diode, a modification of the Crookes tube with a phosphor-coated screen. In 1907, Russian scientist Boris Rosing used a CRT in the end of an experimental video signal to form a picture. He managed to display simple geometric shapes onto the screen, which marked the first time that CRT technology was used for what is now known as television. The first cathode ray tube to use a hot cathode was developed by John B. Johnson and Harry Weiner Weinhart of Western Electric and it was named by inventor Vladimir K. Zworykin in 1929. RCA was granted a trademark for the term in 1932, it released the term to the public domain in 1950. The first commercially made electronic television sets with cathode ray tubes were manufactured by Telefunken in Germany in 1934, in oscilloscope CRTs, electrostatic deflection is used, rather than the magnetic deflection commonly used with television and other large CRTs
5.
Electron
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The electron is a subatomic particle, symbol e− or β−, with a negative elementary electric charge. Electrons belong to the first generation of the lepton particle family, the electron has a mass that is approximately 1/1836 that of the proton. Quantum mechanical properties of the include a intrinsic angular momentum of a half-integer value, expressed in units of the reduced Planck constant. As it is a fermion, no two electrons can occupy the same state, in accordance with the Pauli exclusion principle. Like all elementary particles, electrons exhibit properties of particles and waves, they can collide with other particles and can be diffracted like light. Since an electron has charge, it has an electric field. Electromagnetic fields produced from other sources will affect the motion of an electron according to the Lorentz force law, electrons radiate or absorb energy in the form of photons when they are accelerated. Laboratory instruments are capable of trapping individual electrons as well as electron plasma by the use of electromagnetic fields, special telescopes can detect electron plasma in outer space. Electrons are involved in applications such as electronics, welding, cathode ray tubes, electron microscopes, radiation therapy, lasers, gaseous ionization detectors. Interactions involving electrons with other particles are of interest in fields such as chemistry. The Coulomb force interaction between the positive protons within atomic nuclei and the negative electrons without, allows the composition of the two known as atoms, ionization or differences in the proportions of negative electrons versus positive nuclei changes the binding energy of an atomic system. The exchange or sharing of the electrons between two or more atoms is the cause of chemical bonding. In 1838, British natural philosopher Richard Laming first hypothesized the concept of a quantity of electric charge to explain the chemical properties of atoms. Irish physicist George Johnstone Stoney named this charge electron in 1891, electrons can also participate in nuclear reactions, such as nucleosynthesis in stars, where they are known as beta particles. Electrons can be created through beta decay of isotopes and in high-energy collisions. The antiparticle of the electron is called the positron, it is identical to the electron except that it carries electrical, when an electron collides with a positron, both particles can be totally annihilated, producing gamma ray photons. The ancient Greeks noticed that amber attracted small objects when rubbed with fur, along with lightning, this phenomenon is one of humanitys earliest recorded experiences with electricity. In his 1600 treatise De Magnete, the English scientist William Gilbert coined the New Latin term electricus, both electric and electricity are derived from the Latin ēlectrum, which came from the Greek word for amber, ἤλεκτρον
6.
Sound
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In physics, sound is a vibration that propagates as a typically audible mechanical wave of pressure and displacement, through a transmission medium such as air or water. In physiology and psychology, sound is the reception of such waves, humans can hear sound waves with frequencies between about 20 Hz and 20 kHz. Sound above 20 kHz is ultrasound and below 20 Hz is infrasound, other animals have different hearing ranges. Acoustics is the science that deals with the study of mechanical waves in gases, liquids, and solids including vibration, sound, ultrasound. A scientist who works in the field of acoustics is an acoustician, an audio engineer, on the other hand, is concerned with the recording, manipulation, mixing, and reproduction of sound. Auditory sensation evoked by the oscillation described in, sound can propagate through 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 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 the sound wave. At a fixed distance from the source, the pressure, velocity, at an instant in time, the pressure, velocity, and displacement vary in space. Note that the particles of the medium do not travel with the sound wave and this is intuitively obvious for a solid, and the same is true for liquids and gases. During propagation, waves can be reflected, refracted, or attenuated by the medium, the behavior of sound propagation is generally affected by three things, A complex relationship between the density and pressure of the medium. This relationship, affected by temperature, determines the speed of sound within the medium, if the medium is moving, this movement may increase or decrease the absolute speed of the sound wave depending on the direction of the movement. For example, sound moving through wind will have its speed of propagation increased by the speed of the if the sound and wind are moving in the same direction. If the sound and wind are moving in opposite directions, the speed of the wave will be decreased by the speed of the wind. Medium viscosity determines the rate at which sound is attenuated, for many media, such as air or water, attenuation due to viscosity is negligible. When sound is moving through a medium that does not have constant physical properties, 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 the sound is called the medium, sound cannot travel through a vacuum. Sound is transmitted through gases, plasma, and liquids as longitudinal waves and it requires a medium to propagate
7.
Frequency
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Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as frequency, which emphasizes the contrast to spatial frequency. The period is the duration of time of one cycle in a repeating event, for example, if a newborn babys heart beats at a frequency of 120 times a minute, its period—the time interval between beats—is half a second. Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as vibrations, audio signals, radio waves. For cyclical processes, such as rotation, oscillations, or waves, in physics and engineering disciplines, such as optics, acoustics, and radio, frequency is usually denoted by a Latin letter f or by the Greek letter ν or ν. For a simple motion, the relation between the frequency and the period T is given by f =1 T. The SI unit of frequency is the hertz, named after the German physicist Heinrich Hertz, a previous name for this unit was cycles per second. The SI unit for period is the second, a traditional unit of measure used with rotating mechanical devices is revolutions per minute, abbreviated r/min or rpm. As a matter of convenience, longer and slower waves, such as ocean surface waves, short and fast waves, like audio and radio, are usually described by their frequency instead of period. Spatial frequency is analogous to temporal frequency, but the axis is replaced by one or more spatial displacement axes. Y = sin = sin d θ d x = k Wavenumber, in the case of more than one spatial dimension, wavenumber is a vector quantity. For periodic waves in nondispersive media, frequency has a relationship to the wavelength. Even in dispersive media, the frequency f of a wave is equal to the phase velocity v of the wave divided by the wavelength λ of the wave. In the special case of electromagnetic waves moving through a vacuum, then v = c, where c is the speed of light in a vacuum, and this expression becomes, f = c λ. When waves from a monochrome source travel from one medium to another, their remains the same—only their wavelength. For example, if 71 events occur within 15 seconds the frequency is, the latter method introduces a random error into the count of between zero and one count, so on average half a count. This is called gating error and causes an error in the calculated frequency of Δf = 1/, or a fractional error of Δf / f = 1/ where Tm is the timing interval. This error decreases with frequency, so it is a problem at low frequencies where the number of counts N is small, an older method of measuring the frequency of rotating or vibrating objects is to use a stroboscope
8.
Oscilloscope
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Other signals can be converted to voltages and displayed. Oscilloscopes are used to observe the change of a signal over time, such that voltage. The observed waveform can be analyzed for such properties as amplitude, frequency, rise time, time interval, distortion, modern digital instruments may calculate and display these properties directly. Originally, calculation of these values required manually measuring the waveform against the scales built into the screen of the instrument, the oscilloscope can be adjusted so that repetitive signals can be observed as a continuous shape on the screen. A storage oscilloscope allows single events to be captured by the instrument and displayed for a long time. Oscilloscopes are used in the sciences, medicine, engineering, automotive, general-purpose instruments are used for maintenance of electronic equipment and laboratory work. Special-purpose oscilloscopes may be used for purposes as analyzing an automotive ignition system or to display the waveform of the heartbeat as an electrocardiogram. Early oscilloscopes used cathode ray tubes as their display element and linear amplifiers for signal processing, storage oscilloscopes used special storage CRTs to maintain a steady display of a single brief signal. CROs were later superseded by digital storage oscilloscopes with thin panel displays, fast analog-to-digital converters. DSOs without integrated displays are available at lower cost and use a digital computer to process. The basic oscilloscope, as shown in the illustration, is divided into four sections. The display is usually a CRT or LCD panel which is out with both horizontal and vertical reference lines referred to as the graticule. In addition to the screen, most display sections are equipped with three controls, a focus knob, an intensity knob and a beam finder button. The vertical section controls the amplitude of the displayed signal and this section carries a Volts-per-Division selector knob, an AC/DC/Ground selector switch and the vertical input for the instrument. Additionally, this section is equipped with the vertical beam position knob. The horizontal section controls the base or sweep of the instrument. The primary control is the Seconds-per-Division selector switch, also included is a horizontal input for plotting dual X-Y axis signals. The horizontal beam position knob is located in this section
9.
Aliasing
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In signal processing and related disciplines, aliasing is an effect that causes different signals to become indistinguishable when sampled. It also refers to the distortion or artifact that results when the signal reconstructed from samples is different from the continuous signal. Aliasing can occur in signals sampled in time, for digital audio. Aliasing can also occur in spatially sampled signals, for instance moiré patterns in digital images, aliasing in spatially sampled signals is called spatial aliasing. Aliasing is generally avoided by applying low pass filters- anti-aliasing filters to the signal before sampling. When a digital image is viewed, a reconstruction is performed by a display or printer device, and by the eyes and the brain. If the image data is processed in some ways during sampling or reconstruction, the image will differ from the original image. An example of aliasing is the moiré pattern observed in a poorly pixelized image of a brick wall. Spatial anti-aliasing techniques avoid such poor pixelizations, aliasing can be caused either by the sampling stage or the reconstruction stage, these may be distinguished by calling sampling aliasing prealiasing and reconstruction aliasing postaliasing. Temporal aliasing is a concern in the sampling of video. Music, for instance, may contain components that are inaudible to humans. If a piece of music is sampled at 32000 samples per second, to prevent this an anti-aliasing filter is used to remove components above the Nyquist frequency prior to sampling. In video or cinematography, temporal aliasing results from the frame rate. Aliasing has changed its apparent frequency of rotation, a reversal of direction can be described as a negative frequency. Like the video camera, most sampling schemes are periodic, that is, digital cameras provide a certain number of samples per degree or per radian, or samples per mm in the focal plane of the camera. Audio signals are sampled with a converter, which produces a constant number of samples per second. Some of the most dramatic and subtle examples of aliasing occur when the signal being sampled also has periodic content, actual signals have finite duration and their frequency content, as defined by the Fourier transform, has no upper bound. Some amount of aliasing always occurs when such functions are sampled, functions whose frequency content is bounded have infinite duration
10.
Wave
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In physics, a wave is an oscillation accompanied by a transfer of energy that travels through a medium. Frequency refers to the addition of time, wave motion transfers energy from one point to another, which displace particles of the transmission medium–that is, with little or no associated mass transport. Waves consist, instead, of oscillations or vibrations, around almost fixed locations, there are two main types of waves. Mechanical waves propagate through a medium, and the substance of this medium is deformed, restoring forces then reverse the deformation. For example, sound waves propagate via air molecules colliding with their neighbors, when the molecules collide, they also bounce away from each other. This keeps the molecules from continuing to travel in the direction of the wave, the second main type, electromagnetic waves, do not require a medium. Instead, they consist of periodic oscillations of electrical and magnetic fields generated by charged particles. These types vary in wavelength, and include radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, waves are described by a wave equation which sets out how the disturbance proceeds over time. The mathematical form of this varies depending on the type of wave. Further, the behavior of particles in quantum mechanics are described by waves, in addition, gravitational waves also travel through space, which are a result of a vibration or movement in gravitational fields. While mechanical waves can be transverse and longitudinal, all electromagnetic waves are transverse in free space. A single, all-encompassing definition for the wave is not straightforward. A vibration can be defined as a back-and-forth motion around a reference value, however, a vibration is not necessarily a wave. An attempt to define the necessary and sufficient characteristics that qualify a phenomenon as a results in a blurred line. The term wave is often understood as referring to a transport of spatial disturbances that are generally not accompanied by a motion of the medium occupying this space as a whole. In a wave, the energy of a vibration is moving away from the source in the form of a disturbance within the surrounding medium and it may appear that the description of waves is closely related to their physical origin for each specific instance of a wave process. For example, acoustics is distinguished from optics in that sound waves are related to a rather than an electromagnetic wave transfer caused by vibration. Concepts such as mass, momentum, inertia, or elasticity and this difference in origin introduces certain wave characteristics particular to the properties of the medium involved
