wiktionary compression compressor Compression may refer to In physical science Compression physical , the result of the subjection of a material to compressive stress Compression member , a class of structural ... of volume change resulting from pressure Gas compression , raising the pressure and reducing the volume of gases Compression ratio , a figure of merit of an internal combustion engine Compression geology , a system of forces that tend to decrease the volume of rocks In information science Data compression , the process of encoding digital information using fewer bits Audio compression data , the compression of digital audio streams and files Bandwidth compression , a reduction in either the time to transmit or in the amount of bandwidth required to transmit Compression artifact , noticeable defects in audio or video that has been compressed Image compression , the application of data compression on digital images Video compression , the compression of digital video streams and files One way compression function , a cryptographic primitive In engineering Dynamic range compression , a compression process that reduces the dynamic range of an audio signal Gain compression , in electronic ... Brain compression , a potentially fatal condition where pressure is exerted on the brain by internal bleeding Bandage Compression bandage Compression bandage , a bandage that uses compression to reduce the flow of blood Intravenous pyelogram compressionCompression in pyelography involves pressing on the lower abdominal area, resulting in distension of the upper urinary tract. In mathematics Compression functional analysis , the compression of a linear operator T on a Hilbert space to a subspace K is the operator Other Compression phonetics , running syllables together in informal speech Please ..., until this articl is created, please do not shorten the description. Compression zoology when an animal ... See also Compaction disambiguation compress Compression shorts Compressor disambiguation Decompression ... more details
Compression therapy may refer to Attachment therapy , a loosely identified category of mental health interventions Cold compression therapy , to reduce pain and swelling from a sports or activity injury disambig ... more details
Context date November 2010 Accessibility dispute date January 2011 Signaling compression , or SigComp , is a compression method designed especially for compression of text based communication data as Session Initiation Protocol SIP or RTSP . SigComp had originally been defined in RFC 3320 and was later updated with RFC 4896. A Negative Acknowledgement Mechanism for Signaling Compression is defined in RFC 4077. The SigComp work is performed in the ROHC working group in the transport area of the IETF . General architecture center Image SigComp Architecture.png center Related standards documents RFC 3320 Signaling Compression SigComp RFC 3321 Signaling Compression SigComp Extended Operations RFC 3485 The Session Initiation Protocol SIP and Session Description Protocol SDP Static Dictionary for Signaling Compression SigComp RFC 3486 Compressing the Session Initiation Protocol SIP RFC 4077 A Negative Acknowledgement Mechanism for Signaling Compression RFC 4464 Signaling Compression SigComp Users Guide RFC 4465 Signaling Compression SigComp Torture Tests RFC 4896 Signaling Compression SigComp Corrections and Clarifications RFC 5049 Applying Signaling Compression SigComp to the Session Initiation Protocol SIP RFC 5112 The Presence Specific Static Dictionary for Signaling Compression Sigcomp 3GPP TR23.979 Annex C Required SigComp performance Category Data compression Category Multimedia Category Telecommunications Category VoIP protocols Category Presentation layer protocols fr SigComp ... more details
Audio compression may refer to Audio compression data , a type of lossy compression in which the amount of data in a recorded waveform is reduced for transmission with some loss of quality, used in CD and MP3 encoding, Internet radio, and the like Dynamic range compression , also called audio level compression, in which the dynamic range, the difference between loud and quiet, of an audio waveform is reduced disambig zh ... more details
Expert subject Computing date May 2011 Adaptive compression is a type of data compression which changes compression algorithm s based on the type of data being compressed. ref name PCMag Cite web url http www.pcmag.com encyclopedia term 0,2542,t adaptive compression&i 37503,00.asp work PC Magizine Encyclopedia title Adaptive compression accessdate 21 April 2011 ref References reflist Category Data compression Computing stub ... more details
Other uses Volume disambiguation Unreferenced date December 2009 A volume is a term in data compression for a file that has been compressed and split into different parts. There are many advantages in having a compression utility with the ability for compression into volumes. First, it allows an individual to download the file in segments at his or her own pace. As well if there is a corruption only one volume is affected instead of the whole which can be corrected using parity file s. Second, it allows compression to a volume size compatible with removable media. For example, compressing a backup into 700MB chunks for easy storage on CDs. See also Compression utilities with volume support RAR ARJ 7 Zip PeaZip DEFAULTSORT Volume Compression Category Data compression ru uk ... more details
Speech compression may mean different things Speech encoding refers to compression for transmission or storage, possibly to an unintelligible state, with decompression used prior to playback. Time compressed speech refers to voice compression for immediate playback, without any decompression so that the final speech sounds faster to the listener . disambig ... more details
Cord compression may refer to Spinal cord compression Umbilical cord compression disambig Short pages monitor This long comment was added to the page to prevent it being listed on Special Shortpages. It and the accompanying monitoring template were generated via Template Longcomment. Please do not remove the monitor template without removing the comment as well. ... more details
Voice compression may mean different things Speech encoding refers to compression for transmission or storage, possibly to an unintelligible state, with decompression used prior to playback. Time compressed speech refers to voice compression for immediate playback, without any decompression so that the final speech sounds faster to the listener . Audio level compression refers to a sound recording effect which increases the perceived volume of a sound. Disambig ... more details
Texture compression is a specialized form of image compression designed for storing texture map s in 3D computer graphics rendering systems. Unlike conventional image compression algorithms, texture compression algorithms are optimized for random access . How it works In their seminal paper on http graphics.stanford.edu projects flashg papers texture compression texture compression ref Citation author Andrew Beers coauthors Maneesh Agrawala, Navin Chaddha title Rendering from Compressed Textures journal Computer Graphics, Proc. SIGGRAPH year 1996 pages 373 378 ref , Beers, Agrawala and Chaddha list four features that tend to differentiate texture compression from other image compression techniques. These features are Decoding Speed It is highly desirable to be able to render directly from the compressed texture data and so, in order not to impact rendering performance, decompression must ... , any texture compression scheme must allow fast random access to decompressed texture data. This tends to rule out image compression schemes such as JPEG or Run length encoding . Compression Rate and Visual Quality In a rendering system, lossy compression can be more tolerable than for other use cases. Encoding Speed Texture compression is more tolerant of asymmetric encoding decoding rates as the encoding ..., most texture compression algorithms involve some form of fixed rate lossy compression lossy vector ... maps, texture compression may also be used to encode other kinds of rendering map, including bump map s and normal mapping surface normal map s. Texture compression may also be used together with other ... of practical texture compression systems are S3 Texture Compression , PVRTC and Ericsson Texture Compression . OpenGL and OpenGL ES, as implemented on many video accelerator cards and mobile GPUs, can support multiple common kinds of texture compression generally through the use of vendor extensions ... Compression Category Texture compression compu graphics stub de Texturkomprimierung es Compresi n de ... more details
Unreferenced date February 2010 Silence Compression provides an excellent way to squeeze Data redundancy redundancy out of the sound files. Silence compression scheme is essential for efficient voice communication system. It allows significant reduction of transmission bandwidth during silence period. A Silence compression scheme include a voice activity detection VAD , a silence insertion descriptor SID and a comfort noise generator CNG module. Parameters used for silence compression threshold value the way to encode silence threshold for recognizing start of silence an indication of when silence is over parameter to get threshold, means there is no silence until unless there is three silence in the rows. Sound tech stub Category Data compression ... more details
In telecommunication , the term signal compression has the following meanings In analog usually audio systems, reduction of the dynamic range of a Signalling telecommunication signal by controlling it as a function of the inverse relationship of its instantaneous value relative to a specified reference level. Signal compression is usually expressed in decibel dB . Instantaneous values of the input signal that are low, relative to the reference level, are increased, and those that are high are decreased. Signal compression is usually accomplished by separate devices called compressors. It is used for many purposes, such as a improving signal to noise ratios prior to digitizing an analog signal for transmission telecommunications transmission over a digital carrier system , b preventing overload of succeeding elements of a system, or c matching the dynamic ranges of two devices. Signalling telecommunication Signal compression in dB may be a linear or nonlinear function of the signal level across the frequency band radio band of interest and may be essentially instantaneous or have fixed or variable delay times. Signal compression always introduces distortion , which is usually not objectionable, if the compression is limited to a few dB. The original dynamic range of a compressed signal may be restored by a Electronic circuit circuit called an Companding expander . FS1037C MS188 See also Companding Dynamic range compression Further reading http www.atis.org tg2k signal compression.html Definition signal compression http users.ece.gatech.edu vkm nii node36.html Signal Compression http www.ece.ucsb.edu scl Signal Compression Lab UCSB http www.stanford.edu group compression Signal Compression and Classification Group Stanford Category Electronics terms Category Signal processing Category Telecommunications terms he ... more details
nofootnotes date April 2010 The objective of image compression is to reduce irrelevance and redundancy ... technique Lossy and lossless compression Image compression may be lossy compression lossy or lossless compression lossless . Lossless compression is preferred for archival purposes and often for medical imaging, technical drawings, clip art , or comics. This is because lossy compression methods, especially when used at low bit rate s, introduce compression artifact s. Lossy methods are especially ... loss of fidelity is acceptable to achieve a substantial reduction in bit rate. The lossy compression that produces imperceptible differences may be called visually lossless compression visually lossless . Methods for lossless image compression are Run length encoding used as default method in PCX and as one ... code s Methods for lossy compression Reducing the color space encoding color space to the most ... image processing quantization and entropy coding . Fractal compression . Other properties The best image quality at a given bit rate or compression rate is the main goal of image compression, however, there are other important properties of image compression schemes Scalability generally refers ... compression . Other names for scalability are progressive coding or embedded bitstreams . Despite ..., and author or copyright information. Processing power . Compression algorithms require different amounts of processing power to encode and decode. Some high compression algorithms require high processing power. The quality of a compression method often is measured by the Peak signal to noise ratio . It measures the amount of noise introduced through a lossy compression of the image, however ...?docid 163332982698249627 MIT Linear Algebra Lecture on Image Compression at Google Video, from MIT OpenCourseWare ... Image compression A study about image compression Image compression basics and comparing different compression methods like JPEG2000, JPEG and JPEG XR HD Photo http dvd hq.info data compression.php ... more details
Orphan date February 2009 Compression , in astronomy is the deviation of a heavenly body from the spherical form, called also the ellipticity . It is numerically expressed by the ratio of the differences of the axes to the major axis of the spheroid. The compression or flattening of the earth is about 1 298, which means that the ratio of the equatorial to the polar axis is 298 297 References 1911 astronomy stub Category Astrometry ... more details
Compression shorts are underwear undergarments usually worn by athletes. They are form fitting garment s and when worn cover the athlete s waist to mid or lower thigh. These garments are often made from a spandex type material, similar to cycling shorts . A major benefit of compression shorts are that they keep the thigh muscles warm to reduce muscle strain and fatigue. In addition, there is some evidence that compression shorts may enhance athletic performance. ref cite journal doi 10.1080 0264041031000101971 author Doan BK, Kwon YH, Newton RU, et al. title Evaluation of a lower body compression garment journal J Sports Sci volume 21 issue 8 pages 601 10 year 2003 month Aug pmid 12875311 ref They are also used as a way to keep the male genitalia in place. Compression shorts also help to keep .... Another major benefit is that many compression shorts are designed to wick sweat away from the body ... things like walking or running when the thighs are adducted. There are also other types of compression garments that serve a similar function, such as compression t shirts, socks, sleeves & tights ... such as compression shorts have seen an increase in popularity, arguably because of their comparable ... all the jockstraps gone? work Slate Magazine 2005 07 22 ref Compression shorts are also popular among ..., athletes wear compression shorts under the skirt so if they fall over and their skirts ride up ... both being no contact sports in which players often wear skirts . In this situation, compression shorts are colloquially identified as spandex shorts. Women also wear compression shorts in tennis where most recently, compression shorts have been produced with ball pockets for convenience. There are also women s compression shorts for use before, during and after pregnancy. Pregnancy compression shorts ... url http www.recoveryshorts.com.au title Women s pregnancy compression shorts 2011 05 31 ref See also Compression sportswear Rugby shorts Sports clothing References reflist Men s undergarments Clothing ... more details
File Compression test.jpg right thumb 250px Compression test on a universal testing machine Physical compression is the result of the subjection of a material or structure to Stress mechanics compressive stress , which results in reduction of volume as compared to an uncompressed but otherwise identical state. The opposite of compression in a solid is tension physics tension . In any medium transmitting waves, the opposite of compression is rarefaction . In simple terms, compression is a pushing force. Explanation Compression has many implications in materials science , physics and structural engineering , for compression yields noticeable amounts of Stress physics stress and tension mechanics tension . By inducing compression, mechanical properties such as compressive strength or modulus of elasticity , can be measured. Scientist s and engineer s may utilize compression machines to measure the resistance of materials and structures to compression. Compression machines range from very small table top systems to ones with over 53 MN capacity. ref Citation last NIST title Large Scale Structure Testing Facility url http www.nist.gov bfrl facilities instruments large scale struct testing fac.cfm accessdate 04 05 2010 postscript . ref In engines Internal combustion engines In internal combustion engine s it is a necessary condition of economy to compress the explosive mixture before it is ignited in the Otto cycle , for instance, the second stroke of the piston effects the compression of the charge which has been drawn into the cylinder by the first forward stroke. Steam engines The term is applied to the arrangement by which the exhaust valve of a steam engine is made to close ... in the mechanism due to the inertia of the reciprocating parts are lessened. This compression, moreover ... stroke. See also Box compression test Buckling Compression member Longitudinal wave P wave ... f sica ru simple Physical compression ... more details
Chest compression may refer to The prevention of the expansion of the chest , see Asphyxia Compressive asphyxia Compressive asphyxia A technique used during cardiopulmonary resuscitation or for the Choking Modified chest thrusts treatment of choking disambig ... more details
unreferenced date September 2010 In the theory of 3 manifold s, a compression body is a kind of generalized handlebody . A compression body is either a handlebody or the result of the following construction Let math S math be a compact, closed surface not necessarily connected . Attach 1 handle mathematics handle s to math S times 0,1 math along math S times 1 math . Let math C math be a compression body. The negative boundary of C, denoted math partial C math , is math S times 0 math . If math C math is a handlebody then math partial C emptyset math . The positive boundary of C, denoted math partial C math , is math partial C math minus the negative boundary. There is a dual construction of compression bodies starting with a surface math S math and attaching 2 handles to math S times 0 math . In this case math partial C math is math S times 1 math , and math partial C math is math partial C math minus the positive boundary. Compression bodies often arise when manipulating Heegaard splitting s. Geometry stub Category 3 manifolds ... more details
Unreferenced date December 2009 Orphan date December 2009 A rotary compression pump works in cycles. Over each cycle a volume is created in contact with the cavity where pressure is to be lowered. By random motion, molecules from the vacuum pass into the volume created by the pump. This volume is then cut off from the cavity and compressed in contact with a one way valve. If the volume is compressed enough some of the molecules will pass through the valve. The maximum efficiency of a rotary compression pump is the ratio between the volume in contact with the vacuum and the smallest contracted volume in contact with the valve. If the ratio is 1 1000 and the pump is exhausting to atmospheric pressure, the highest achievable vacuum is 1 1000 of atmospheric pressure. This corresponds to 0.76 Torr or 101.3 Pascal pressure Pa . This limitation makes rotary compression pumps very hard to construct if lower pressures than about 1 Torr is to be achieved. The simplicity of the process makes the rotary compression pump cheap and it is widely used as a low vacuum pump or a fore pump to a diffusion pump . See also rotary vane pump DEFAULTSORT Rotary Compression Category Pumps ... more details
as a digital logic circuit, but it could also function as an analog amplifier it shows gain compression at the edges of the diagonal slope, where rounding of the line yields soft clipping. Gain compression ... large signal phenomenon of circuits. Relevance Gain compression is relevant in any system with a wide ... depends on the topology of the amplifier. Differences between clipping and compression Clipping, as a form of signal compression, differs from the operation of the typical studio audio level compression audio level compressor , in which gain compression is not instantaneous delayed in time via attack .... Compression and limiting change the shape of the entire waveform, not just the shape of the waveform ... causing distortion. Limiting or clipping Gain is a linear operation. Gain compression is not linear ... have many extra harmonics . CompressionCompression of gain is caused by non linear characteristics ... the linear range of the amplifier, gain compression will occur. A transistor s operating point may move with temperature, so higher power output may lead to compression due to collector dissipation ... in output. Thus there is compression of gain. Also, at this time because the transfer function is no longer linear, harmonic distortion will result. Intentional compression In intentional compression sometimes called automatic gain control or audio level compression as used in devices called dynamic ... be the same amplitude. Radio frequency compression Gain compression in RF amps is similar to soft clipping. However, in narrowband systems, the effect looks more like gain compression simply ... gain compression rather than distortion figures because it s easier to measure and is more important ... s picking up. Examples of RF compression A low noise linear amplifier RF amplifier if fed by a directional ... and generate mixing products. This is a typical effect of gain compression. High power loudspeakers A form of gain compression also takes place in loudspeaker voice coil s when they heat up and increase ... more details
HTTP HTTP compression is a capability that can be built into web server s and web client s to make better ... 24eb4f312e0e.mspx?mfr true title Using HTTP Compression IIS 6.0 accessdate 9 February 2010 publisher Microsoft Corporation ref HTTP data is Data compression compressed before it is sent from the server ... format browsers that do not support compliant compression method will download uncompressed data. The most common compression schemas include gzip and zlib deflate , however a full list of available ... with overcautious web browsers , where servers are misconfigured, and where browser bugs stop compression being used. Internet Explorer 6, which drops to HTTP 1.0 without features like compression ... use compression.html ref Client Server compression scheme negotiation In most cases, excluding the SDCH ... Encoding field in the HTTP request, with supported compression schema names called content coding ... gzip, deflate 2. If the server supports one or more compression schemas, the outgoing data may be compressed ... to use any compression method this depends on the internal settings of the web server and also ... its name the zlib compression RFC 1950 should be used in combination with the deflate compression ... the zlib compression and the raw deflate compression. ref cite web url http www.vervestudios.co projects compression tests title Compression Tests accessdate 23 March 2011 publisher Verve Studios ... supported as of March 2011. ref cite web url http www.vervestudios.co projects compression tests results title Compression Tests Results accessdate 23 March 2011 publisher Verve Studios, Co ref identity ... Format for Java Archives. ref SDCH sdch Google Shared Dictionary Compression for HTTP bzip2 free and open source lossless data compression algorithm PeerDist peerdist Microsoft Peer Content Caching ... PCCRPT Servers that support HTTP compression SAP NetWeaver Internet Information Services Microsoft ... only supporting gzip ref cite web url http www.vervestudios.co projects compression tests title ... more details
Compression garments are pieces of clothing such as socks, pantyhose , sleeves, etc, that provide support that is especially useful for people who have to stand for long periods, or people with poor circulation. The garments can come in varying degrees of compression. The higher degrees require a doctor s prescription. Compression garments worn on the legs can help prevent deep vein thrombosis and reduce swelling, especially while traveling. Compression tights are also worn by some athletes. Research Through testing repeat sprint and throwing performance in cricket players, it was found that there was a significant difference p 0.05 by way of higher mean skin temperature, lower 24 hour post exercise Creatine kinase CK values and lower 24 hour post exercise ratings of muscle soreness when wearing compression garments. ref cite journal pmid 17341589 year 2007 author1 Duffield first2 M title Comparison of three types of full body compression garments on throwing and repeat sprint performance in cricket players volume 41 issue 7 pages 409 14 discussion 414 doi 10.1136 bjsm.2006.033753 journal British journal of sports medicine first3 J. ref In materials testing, the compressive garment provided increased flexion and extension, which could help reduce hamstring injuries. They also reduced impact by 27 compared to American football pants alone. ref cite journal pmid 12875311 year 2003 author1 Doan first2 YH first3 RU first4 J first5 EM first6 RA first7 LR first8 M first9 WJ title Evaluation of a lower body compression garment volume 21 issue 8 pages 601 10 journal Journal of sports sciences doi 10.1080 0264041031000101971 ref br Br See also Compression stockings Pantyhose for men Compression shorts References reflist Category Medical equipment ... more details
For compression ratio in data compression data compression ratio Refimprove date May 2009 The compression ... Compression ratio url http www.britannica.com EBchecked topic 130313 compression ratio accessdate 2009 ... the head or combustion chamber has been reduced to 100 cc, then the compression ratio would be proportionally described as 1000 100, or with fractional reduction, a 10 1 compression ratio. A high compression ratio is desirable because it allows an engine to extract more mechanical energy from ... of thermal efficiency, it is because greater compression increases the internal energy ... of the compression. date April 2011 High ratios place the available oxygen and fuel molecules into a reduced space along with the adiabatic heat of compression causing better mixing and evaporation of the fuel droplets. Citation needed reason you should not say adiabatic heat of compression ... usually refers to a process. You should say along with the adiabatic tendancies of the compression process or along with the fact that the compression process is adiabatic. Also it does not really ..., as opposed to energy which is a physical property. date April 2011 Higher compression ratios will however ... of compression ignition, so that a fuel which resists autoignition will cause late ignition which ... of the compression stroke, i.e. when the piston reaches top dead center TDC . Because of the complex shape of this space, it is usually measured directly rather than calculated. Typical compression ratios Petrol gasoline engine Due to engine knocking pinging detonation , the compression ratio ... automotive engines built for high performance from 1955 1972 had compression ratios as high ... to adopt a very fast circular rotation in the cylinder during compression that provides quicker ... to delay ignition timing, it is possible to manufacture gasoline engines with compression ratios of over ..., Jaguar released a cylinder head that allowed up to 14 1 compression but settled for 12.5 1 in production ... more details
Image Lepakshi2.jpg thumb right 150px Columns A compression member is a general class of structural elements of which a column is the most common specific example. Description For a compression member, such as a column, the principal stress comes mainly from axis of rotation axial forces, that is forces that fall along one line, usually the centerline. ref name efunda cite web url http www.efunda.com formulae solid mechanics columns intro.cfm title Compression member publisher accessdate 2007 01 08 ref The loading capacity of a short column is determined by strength limit of the material. The strength of a column of intermediate size is limited by its degree of inelasticity. A long column is constrained by the elastic limit that is by amount of buckling . ref name efunda See also Arch Brown truss List of structural elements Truss Strut Notes references External links http www.digitalengineeringlibrary.com dxreader opendxreader.asp?chapterid p2000a1fb9970525001 Columns and other compression members http www.sandsmachine.com ac comp.htm Bicycle compression members http pubsindex.trb.org document view default.asp?lbid 731981 Numerical load numbers for reinforced concrete compression members Category Columns and entablature element arch stub cs Podp rn l nek ... more details
merge Compression garment discuss Talk Compression sportswear Merger proposal date February 2012 Compression sportswear is clothing usually worn by athletes. They may be shorts, tights or underwear. They are form fitting garment s and when worn cover the athlete s waist to mid or lower thigh. These garments are often made from a spandex type material. The main benefits of compression sportswear is that it keeps the muscles warm to prevent muscle strain and fatigue, and wick sweat away from the body to prevent chafing and rashes. In addition, there is some evidence that compression shorts may enhance athletic performance. ref cite journal doi 10.1080 0264041031000101971 author Doan BK, Kwon YH, Newton RU, et al. title Evaluation of a lower body compression garment journal J Sports Sci volume 21 issue 8 pages 601 10 year 2003 month Aug pmid 12875311 ref Compression sportswear also helps to keep undergarments in place, and for certain sports, like baseball and softball , come with padding at the hips to protect players from injuries due to sliding. There are many types of compression garments that serve a similar function, such as compression t shirts, socks, sleeves, and tights . Common ..., and garments such as compression shorts have seen an increase in popularity, arguably because of their comparable ... title Where have all the jockstraps gone? work Slate Magazine 2005 07 22 ref Compression shorts .... In those situations, athletes wear compression shorts under the skirt so if they fall over and their skirts .... In this situation, compression shorts are often referred to as spandex shorts, the material with which they are often manufactured. Benefits The alleged benefits of wearing compression tights are Improving ... last7 Duncan last8 Volek last9 Putukian title Influence of compression therapy on symptoms following ... to compression stockings they can be worn during long flights to reduce the risk of Deep vein ... both the duration and intensity of training and competition. See also Compression shorts Rugby ... more details
Encyclopedia
top
