about attenuation in physics other uses Attenuation disambiguation Image B&W girl portrait with sunglasses.jpg ... component In physics , attenuation in some contexts also called extinction is the gradual ... engineering and telecommunications , attenuation affects the propagation of waves and signals in electrical circuits, in optical fibers, as well as in air radio waves . Background In many cases, attenuation ..., this is known as the Beer Lambert law . In engineering, attenuation is usually measured in units of decibels per unit length of medium dB cm, dB km, etc. and is represented by the attenuation coefficient ..., Mosby Inc., 1996. ref Image Micrwavattrp.png thumb Frequency dependent attenuation of electromagnetic radiation in standard atmosphere. Attenuation also occurs in earthquakes when the seismic waves ... . Ultrasound One area of research in which attenuation figures strongly is in ultrasound physics. Attenuation ... through the imaging medium. Accounting for attenuation effects in ultrasound is important because a reduced signal amplitude can affect the quality of the image produced. By knowing the attenuation ... Ultrasound, Stewart C. Bushong and Benjamin R. Archer, Mosby Inc., 1991. ref Ultrasound attenuation ... of particles by acoustic methods ref Ultrasound attenuation can be used for extensional ... viscosity and volume viscosity . Attenuation coefficient Attenuation coefficient s are used ... as a function of frequency. The attenuation coefficient math alpha math can be used to determine total attenuation in dB in the medium using the following formula math text Attenuation alpha text dB ... length and attenuation coefficient, attenuation is also linearly dependent on the frequency of the incident ultrasound beam. Attenuation coefficients vary widely for different media. In biomedical ultrasound imaging however, biological materials and water are the most commonly used media. The attenuation ... . The attenuation in the signal of ground motion intensity plays an important role in the assessment ... more details
Attenuation is the gradual loss in intensity of any kind of flux through a medium. Attenuation may also refer to Attenuation brewing , the percent of sugar converted to alcohol and carbon dioxide by the yeast in brewing Attenuation coefficient , a basic quantity used in calculations of the penetration of materials by quantum particles or other energy beams Mass attenuation coefficient , a measurement of how strongly a chemical species or substance absorbs or scatters light at a given wavelength, per unit mass Regression dilution , a cause of statistical bias The process of producing an attenuated vaccine by reducing the virulence of a pathogen Attenuation constant, the real part of the propagation constant See also Attenuator disambiguation disambig ... more details
Attenuation distortion ref Rowe, Standord H. II, Network Technology & Service Integration 5th Edition , 2002, Prentice Hall, Inc., 2002 ref is the distortion of an analog signal that occurs during Transmission telecommunications transmission when the transmission medium does not have a flat frequency response across the Bandwidth signal processing bandwidth of the medium or the frequency spectrum of the signal. Attenuation distortion occurs when some frequencies are attenuate d more than other frequencies. When an analog signal of constant amplitude across its frequency spectrum suffers attenuation distortion, some frequencies of the received signal arrive being greater in amplitude louder , relative to other frequencies. To overcome the effects of attenuation distortion, communications circuit s have special equalization equipment attached at the ends of the circuit or in between, designed to attenuate the signal evenly across the frequency spectrum, or to allow the signal to be received at equal amplitude for all frequencies. Attenuation distortion can still occur in a properly equipped circuit if this equalization filter is not properly maintained or adjusted. In DSL circuits, reflection electrical echoes due to Impedance matching impedance mismatch often cause attenuation distortion so severe that some frequencies must be automatically mapped out and not used. References references Category Audio effects ... more details
In brewing attenuation is the percentage that measures the conversion of sugar s into ethanol alcohol and carbon dioxide by the Ethanol fermentation fermentation process. The percentage is calculated by comparing weight or specific gravity of the extract before and after fermentation. Attenuation 100 starting extract current extract starting extract This formula works with extract given in weight percentages or degree Plato. Extract refers to all the non water substances sugars, dextrins, proteins, vitamins, minerals, etc. that are present in the wort. The percent extract or Plato scale is a measure in percent of how much of the wort s weight is extract. Since, at least in the wort and beer gravities that most brewers work with, an almost linear relationship between specific gravity 1 and extract percentages exists, the above formula can also be expressed as Attenuation 100 starting gravity current gravity starting gravity 1 for brewers who prefer to work with specific gravity. Sources div class references small braukaiser.com http braukaiser.com wiki index.php?title Understanding Attenuation Understanding Attenuation div DEFAULTSORT Attenuation Category Brewing drink stub ... more details
For attenuation coefficient as it applies to electromagnetic theory and telecommunications see Propagation constant Attenuation constant propagation constant . For the mass attenuation coefficient , see the article mass attenuation coefficient . The attenuation coefficient is a quantity that characterizes ... , particle s, or other energy or matter . A large attenuation coefficient means that the beam is quickly attenuated weakened as it passes through the medium, and a small attenuation coefficient means that the medium is relatively transparent to the beam. Attenuation coefficient is measured using units of reciprocal length . The attenuation coefficient is also called linear attenuation coefficient , pencil beam narrow beam attenuation coefficient , or absorption coefficient . Although all four ... Attenuation versus absorption below . Overview The attenuation coefficient describes the extent to which ... . In the case of Attenuation Ultrasound ultrasound attenuation it is usually denoted as math alpha ... colloids , Elsevier, 2002 ref The attenuation coefficient is widely used in acoustics for characterizing ... ref Note that the sabin is not a unit of attenuation coefficient rather, it is the unit of a related quantity. A small linear attenuation coefficient indicates that the material in question is relatively ... opacity . The linear attenuation coefficient is dependent upon the type of material and the energy ... photons and the less dense the material in question, the lower the corresponding linear attenuation ... I I 0 , e alpha , x , math where math x math denotes the path length. The attenuation coefficient or linear attenuation coefficient is math alpha math . The Half Value Layer HVL signifies the thickness ... from potentially harmful radiation. The attenuation factor of a material is obtained by the ratio of the emergent and incident radiation intensities math I I 0 math . The linear attenuation coefficient and mass attenuation coefficient are related such that the mass attenuation coefficient is simply ... more details
No footnotes date January 2010 In physics , the attenuation length or absorption length is the distance math lambda math into a material when the probability has dropped to math 1 e math that a Elementary particle particle has not been Absorption electromagnetic radiation absorbed . Alternatively, if there is a beam of particles incident on the material, the attenuation length is the distance where the intensity physics intensity of the beam has dropped to math 1 e math , or about 63 of the particles have been stopped. Mathematically, the probability of finding a particle at depth x into the material is calculated by Beer Lambert law math P x e x lambda , math . In general math lambda math is material dependent. See also Beer s Law Mean free path Attenuation coefficient Attenuation electromagnetic radiation Radiation length References S. Eidelman et al. Particle Data Group , Review of particle physics , Phys. Lett. B 592 2004 http pdg.lbl.gov http www.ct.infn.it rivel Glossario node2.html External links http henke.lbl.gov optical constants atten2.html Category Particle physics Category Experimental particle physics particle stub de Absorptionsl nge it Lunghezza di attenuazione ... more details
Growth attenuation is an elective medical treatment which involves administering estrogen to cause closure of the epiphysis epiphyses of the bone s Epiphyseal plate s , resulting in a reduced adult height. Since the 1960s this treatment has been performed primarily on children growing toward an adult height considered unacceptably excessive by their parents and doctors. The cultural consensus of what is considered an excessive height justifying treatment has differed in Europe and North America and has risen over the last 4 decades. ref Joyce M. Lee and Joel D. Howell. http archpedi.ama assn.org cgi content abstract 160 10 1035 Tall Girls The Social Shaping of a Medical Therapy Archives of Pediatrics & Adolescent Medicine , Vol. 160 No. 10, October 2006. ref Most of the children treated have been girls, with larger numbers treated in Europe than in North America. The height considered unacceptable by parents and doctors has become substantially taller over the last few decades. Very few boys have ever been treated for excessive tallness in North America, but this also has been done more often in Europe. More recently, growth attenuation treatment has been in the news as part of the controversial Ashley Treatment administered to a developmentally disabled girl. References references DEFAULTSORT Growth Attenuation Category Medical ethics Category Medical treatments Category Pediatrics medical stub ... more details
Correction for attenuation is a statistical procedure, due to Charles Spearman Spearman 1904 , to rid a correlation coefficient from the weakening effect of measurement error Jensen, 1998 , a phenomenon also known as regression dilution . In measurement and statistics , it is also called disattenuation . The correlation between two sets of parameters or measurements is the estimated a manner that accounts for measurement error contained within the estimator estimates of those parameters. Background Correlations between parameters are diluted or weakened by measurement error. Disattenuation provides for a more accurate estimate of the correlation between the parameters by accounting for this effect. Derivation of the formula Let math beta math and math theta math be the true values of two attributes of some person or statistical unit . These values are regarded as random variables by virtue of the statistical unit being selected randomly from some statistical population population . Let math hat beta math and math hat theta math be estimates of math beta math and math theta math derived either directly by observation with error or from application of a measurement model, such as the Rasch model . Also, let math hat beta beta epsilon beta , quad quad hat theta theta epsilon theta, math where math epsilon beta math and math epsilon theta math are the measurement errors associated with the estimates math hat beta math and math hat theta math . The correlation between two sets of estimates is math operatorname corr hat beta , hat theta frac operatorname cov hat beta , hat theta sqrt operatorname var hat beta operatorname var hat theta math math frac operatorname cov beta epsilon ... for attenuation is math r x y frac r xy sqrt r xx r yy math . How well the variables are measured affects the correlation of X and Y . The correction for attenuation tells you what the correlation ... and regression coefficients Jason W. Osborne DEFAULTSORT Correction For Attenuation Category ... more details
Unreferenced auto yes date December 2009 In telecommunications , the Propagation constant Attenuation constant attenuation to Crosstalk electronics crosstalk ratio is the ratio of the attenuated signal information theory signal to near end crosstalk NEXT . It s a factor in determining how far a signal can be transmitted in any given medium. DEFAULTSORT Attenuation To Crosstalk Ratio Category Telecommunications terms Telecomm term stub de Attenuation To Crosstalk Ratio fr Attenuation to crosstalk ratio ... more details
The mass attenuation coefficient is a measurement of how strongly a chemical species or substance absorbance ... light, mass attenuation coefficients can be defined for other electromagnetic radiation such as X ray s , sound , or any other beam that attenuates. The mass attenuation coefficient is also called ... used interchangeably, they can occasionally have a subtle distinction, as explained Attenuation versus ... Beer Lambert law The defining equation for the mass attenuation coefficient is essentially a different ..., math mu math is the attenuation coefficient . When discussing the mass attenuation coefficient, this equation ... mu rho math is the mass attenuation coefficient and math rho ell math is the area density known also as mass thickness. In accordance with the above, the mass attenuation coefficient is equal to the attenuation coefficient divided by the density. In solutions In chemistry, mass attenuation coefficients are often used for a chemical species dissolved in a solution . In that case, the mass attenuation ... chemical species, and the attenuation is the attenuation due to only that one chemical species. The actual attenuation coefficient is computed by math mu mu rho 1 rho 1 mu rho 2 rho 2 cdots math where each term in the sum is the mass attenuation coefficient and density of a different component of the solution the solvent must also be included . This is a convenient concept because the mass attenuation ... . They are quantitatively related by Mass attenuation coefficient Molar mass Molar absorptivity . Units The attenuation coefficient has units of inverse length , while density has units of mass per volume. Since the mass attenuation coefficient is the ratio of these two, we find that it has ... cm sup 2 sup g sup 1 sup the most common unit for X ray mass attenuation coefficients and mL g sup 1 sup cm sup 1 sup sometimes used in solution chemistry . Mass attenuation coefficients for X rays Image Attenuation Coefficient Iron.svg thumb right 400px Mass Attenuation Coefficient of Iron with contributing ... more details
Ultrasound attenuation spectroscopy is a method for characterizing properties of fluids and dispersed particles . It is also known as acoustic spectroscopy There is an international standard for this method. ref ISO 20998 1 2006 Measurement and characterization of particles by acoustic methods ref ref Dukhin, A.S. and Goetz, P.J. Ultrasound for characterizing colloids , Elsevier, 2002 ref Measurement of attenuation coefficient versus ultrasound frequency yields raw data for further calculation of various system properties. Such raw data are often used in the calculation of the particle size distribution in heterogeneous systems such as emulsion s and colloid s. In the case of acoustic rheometer s, the raw data are converted into extensional viscosity or volume viscosity . Instruments that employ ultrasound attenuation spectroscopy are referred to as Acoustic spectrometers. References references External links http www.iop.org EJ abstract 0957 0233 1 6 008 Ultrasonic Spectrometer DEFAULTSORT Ultrasound Attenuation Spectroscopy Category Acoustics Category Colloidal chemistry Category Spectroscopy chem stub de Ultraschalld mpfungsspektroskopie ... more details
About sound attenuation in fluids Stokes disambiguation Stokes Stokes derived a law for the attenuation of sound in a Newtonian fluid ref Stokes, G.G. On the theories of the internal friction in fluids in motion, and of the equilibrium and motion of elastic solids , Transaction of the Cambridge Philosophical Society , vol.8, 22, pp. 287 342 1845 ref . According to this law attenuation of sound is proportional to the dynamic viscosity , square of the sound frequency , and reciprocally proportional to the fluid density and cubic power of sound speed V math alpha frac 2 eta omega 2 3 rho V 3 math Attenuation is expressed in neper per meter in this equation. The author of this law is the same famous George Gabriel Stokes who derived well known Stokes law for the friction force in fluids. It is 160 years old. This remarkable law does not contain unknown or un measurable parameters. It is convenient to convert attenuation into other units, by normalizing attenuation with respect to frequency, because the attenuation typically increases rapidly with frequency. These new units make more adequate presentation of attenuation within a wide frequency range. It is seen that attenuation of the Newtonian fluid, presented in these units, becomes a linear function of frequency. There has been substantial theoretical development in this field since Stokes pioneering work. It has brought one important correction to the Stokes law. It turns out that in addition to the dynamic viscosity the parameter of volume viscosity sup v sup also affects the total attenuation according to the following relationship math alpha frac 2 eta eta v omega 2 3 rho V 3 math The parameter volume viscosity is surprisingly little known despite its fundamental role for fluid dynamics at high frequencies . This parameter ... sound attenuation at very high frequencies math 2 left frac alpha V omega right 2 frac 1 sqrt 1 omega ... practical purposes of describing sound attenuation in Newtonian fluids Stokes law is clearly sufficient ... more details
Multiple issues notability October 2010 original research October 2010 One of the causes of attenuation of radio propagation is the absorption by the atmosphere . There are many well known facts on the phenomenon and qualitative treatments in textbook s ref name ReferenceA Antennas and radiowave propagation . R. E. Collin. Mc Graw Hill, 1985 ref . A document published by the International Telecommunication Union ITU ref name ReferenceC ITU recommendation ITU R pp. 676 8, 2009 ref provides some basis for a quantitative assessment of the attenuation. That document describes a simplified model along with semi empirical formulas based on data fitting . It also recommended an algorithm to compute the attenuation of radiowave propagation in the atmosphere. NASA also published a study on a related subject ref name ReferenceD http trs new.jpl.nasa.gov dspace handle 2014 41145 . NASA progress report ref . Free software based on ITU R recommendations of the French Spatial Reasearches Institute http logiciels.cnes.fr PROPA fr logiciel.htm CNES for download is also available to the public. The model ... attenuation coefficient g expressed in dB km. All the increments g dL are added to provide the total attenuation. Note that the algorithm does not guaranty that the target is actually reached ... up, the attenuation is negligible. The paths of the three are plotted File The3methods.png The linear ... is at 30 km altitude the attenuation found by the boundary value method is 11.33 dB. The previous point of view of worst case leads to an elevation angle of 1.87 degree and an attenuation of 170.77 dB. With this kind of attenuation, every system would be unusable It was found also for this case ... List of numerical analysis software and it offers a higher precision order. The attenuation mechanism ... Use dmy dates date October 2010 External links http pediaview.com openpedia AttenuationAttenuation ... Radiowave Attenuation In The Atmosphere, Computation Of Category Applied mathematics Category Communication ... more details
The ITU Indoor Propagation Model , also known as ITU Model for Indoor Attenuation , is a radio propagation model that estimates the path loss inside a room or a closed area inside a building delimited by walls of any form. Suitable for appliances designed for indoor use, this model approximates the total path loss an indoor link may experience. Applicable to under conditions This model is applicable to only the indoor environments. Typically, such appliances use the lower microwave bands around 2.4 GHz. However, the model applies to a much wider range. Coverage Frequency 900 MHz to 5.2 GHz Floors 1 to 3 Mathematical formulations The model The ITU indoor path loss model is formally expressed as math L 20 log f N log d P f n 28 math where, L the total path loss . Unit decibel dB . f Frequency of transmission. Unit megahertz MHz . d Distance. Unit metre m . N The distance power loss coefficient. n Number of floors between the transmitter and receiver. P sub f sub n the floor loss penetration factor. Calculation of distance power loss coefficient The distance power loss coefficient, N is the quantity that expresses the loss of signal power with distance. This coefficient is an empirical one. Some values are provided in Table 1. ref name ITU 2 Propagation data and prediction methods for the planning of indoor radio communication systems and the radio local area networks in the frequency range 900 MHz to 100 GHz, ITU R Recommendations, Geneva, 2001 ref class wikitable Frequency Band Residential Area Office Area Commercial Area 900 MHz N A 33 20 1.2 GHz N A 32 22 1.3 GHz N A 32 22 1.8 GHz 28 30 22 4 GHz N A 28 22 5.2 GHz N A 31 N A Calculation of floor penetration loss factor The floor penetration loss factor is an empirical constant dependent on the number of floors the waves need to penetrate. Some values are tabulated in Table 2. ref name ITU 2 class wikitable Frequency Band Number of Floors Residential Area Office Area Commercial Area ... more details
Stokes law can refer to Stokes law for friction force Stokes law sound attenuation law describing attenuation of sound in Newtonian liquids For integration, see Stokes theorem . dab ... more details
Acoustic spectroscopy may refer to Spectrogram metry plotting the energy versus frequency over time Ultrasound attenuation spectroscopy , instead of energy, the attenuation coefficient is measured versus frequency disambig ... more details
Stokes formula can refer to Stokes law for friction force in a viscous fluid. Stokes law sound attenuation law describing attenuation of sound in Newtonian liquids. Stokes theorem on the integration of differential forms. dab ... more details
seealso AttenuationAttenuation disambiguation An attenuator could mean Attenuator electronics , an electronic device that reduces the amplitude of a signal Optical attenuator , a device or instrument to reduce light power Attenuator genetics , a specific regulatory sequence transcribed into RNA Impact attenuator , used on highways as a crumple zone in case of a car crash disambig es Atenuador ... more details
Summary Representation of speeds obtainable for different ADSL technologies with respect to line attenuation. Original template image can be found at http whatismyspeed.sourceforge.net demo images myimage.gif Licensing PD ineligible ... more details
ND2 can mean several things Neutral density filter ND with an attenuation factor of 2, or simply ND2 MT ND2 , NADH dehydrogenase subunit 2, or simply ND2 China Railways ND2 diesel electric locomotive dab ... more details
ND4 can mean several things Neutral density filter ND with an attenuation factor of 4, or simply ND4 MT ND4 , NADH dehydrogenase subunit 4, or simply ND4 dab ... more details
The D region is the portion of the ionosphere that exists approximately 50 to 95 km above the surface of the Earth. Note Attenuation of radio waves, caused by ionospheric free electron density generated by solar radiation, is pronounced during daylight hours. Because solar radiation is not present at night, ionization ceases, and hence attenuation of radio waves ceases. References FS1037C MS188 Category Atmosphere et D kiht es Regi n D pt Camada D ... more details
In telecommunication , the term shadow loss has the following meanings The attenuation electromagnetic radiation attenuation caused to a radio signal by obstructions in the propagation path . In a reflector antenna reflector antenna , the relative reduction in the effective aperture antenna aperture of the antenna caused by the masking effect of other antenna parts, such as a feed horn or a secondary reflector, which parts obstruct the radiation path. References FS1037C MS188 Category Radio frequency propagation telecomm term stub ... more details
Multiple issues orphan January 2011 date January 2011 ITU R P.525 is the International Telecommunications Union radiocommunication s standard for the calculation of free space attenuation . DEFAULTSORT Itu R P.525 Category ITU R recommendations Category Standards Wireless stub ... more details
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