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Encyclopedia results for Computational hardness assumption

Computational hardness assumption





Encyclopedia results for Computational hardness assumption

  1. Computational hardness assumption

    assumptions on the computational hardness are stronger than others. Note that if assumption A is stronger than assumption B, that means solving the problem underlying assumption B is polytime reducible to solving the problem underlying assumption A which means that if B is solvable in poly time, A definitely ... Naccache Stern cryptosystem Phi hiding assumption stronger than factorization Cachin Micali Stadler Private information retrieval PIR Discrete log problem DLP Computational Diffie Hellman assumption CDH stronger than DLP Diffie Hellman key exchange Decisional Diffie Hellman assumption DDH stronger than CDH ElGamal encryption Non cryptographic hardness assumptions As well as their cryptographic applications, hardness assumptions are used in computational complexity theory to provide evidence ... proves that the hardness assumption implies some desired complexity theoretic statement, instead of proving that the statement is itself true. The best known assumption of this type is the assumption .... Because hardness of a problem is difficult to prove, in practice certain problems are assumed to be difficult. Common cryptographic hardness assumptions There are many common cryptographic hardness ... common cryptographic hardness assumptions, and some cryptographic protocols that use them. Integer ... Goldwasser Micali cryptosystem Decisional composite residuosity assumption stronger than factorization ... contribution On the Unique Games Conjecture title Proc. 25th IEEE Conference on Computational Complexity ... . ref References reflist Category Theory of cryptography Category Computational number theory ar ...   more details



  1. Computational Diffie?Hellman assumption

    The computational Diffie Hellman CDH assumption is the assumption that a certain computational problem within a cyclic group is hard. Consider a cyclic group G of order  q . The CDH assumption states that, given math g,g a,g b , math for a randomly chosen generator g and random math a,b in 0, ldots, q 1 , , math it is computationally intractable to compute the value math g ab . , math The security of many cryptosystem s is based on the CDH assumption, including notably the Diffie Hellman key agreement scheme. Also, the confidentiality of ElGamal encryption is equivalent to the CDH assumption though the semantic security of the scheme is based on the decisional Diffie Hellman assumption . The CDH assumption is related to the discrete logarithm assumption , which holds that computing the discrete logarithm of a value base a generator math g math is hard. If taking discrete logs in math mathbb G math were easy, then the CDH assumption would be false given math g,g a,g b , , math one could efficiently compute math g ab math in the following way compute math a math by taking the discrete log of math g a math to base math g math compute math g ab math by exponentiation math g ab g b a math It is an open problem to determine whether the discrete log assumption is equivalent to CDH, though in certain special cases this can be shown to be the case. The CDH assumption is also related to the decisional Diffie Hellman assumption DDH , which holds that it is hard to distinguish tuples of the form math g,g a,g b,g ab math from random tuples. If computing math g ab math from math g,g a,g b math were easy, then one could detect DDH tuples trivially. It is believed that CDH is a weaker assumption than DDH there are groups for which detecting DDH tuples is easy, but solving CDH problems is believed to be hard. See also Diffie Hellman problem Diffie Hellman key exchange References Variations ... PDF C94 271.PDF pdf file Category Asymmetric key cryptosystems Category Computational hardness assumptions ...   more details



  1. Hardness

    About mechanical properties of materials Hard disambiguation Hard Hardness is the measure of how resistant ... hardness is generally characterized by strong intermolecular bond s, but the behavior of solid materials under force is complex therefore there are different measurements of hardness scratch hardness , indentation hardness , and rebound hardness . Hardness is dependent on ductility , Elasticity physics ... matter . Measuring hardness Image Vickers tester.png thumb A Vickers hardness tester There are three main types of hardness measurements scratch , indentation , and rebound . Within each of these classes of measurement there are individual measurement scales. For practical reasons hardness comparison conversion tables are used to convert between one scale and another. Scratch hardness Anchor Scratch hardness Scratch hardness is the measure of how resistant a sample is to fracture or permanent ... hardness main Indentation hardness Indentation hardness measures the resistance of a sample to permanent ... hardness scales are Rockwell scale Rockwell , Vickers hardness test Vickers , Shore scale Shore , and Brinell hardness test Brinell . Rebound hardness Rebound hardness, also known as dynamic hardness ... a material. This type of hardness is related to elasticity physics elasticity . The device used ... to rebound hardness and scleroscope test date 2006 12 10 url http www.articlestree.com science a guide to rebound hardness and scleroscope test tx301428.html accessdate 2008 09 08 postscript . ref Two scales that measures rebound hardness are the Leeb rebound hardness test and Bennett hardness scale ... shape when the pressure is removed. Hardness in the elastic range a small temporary change in shape ... properties of scratch and indentation hardness, as described and measured in materials science. Some ... to absorb large amounts of energy. Hardness increases with decreasing particle size . This is known as the Hall Petch relationship . However, below a critical grain size, hardness decreases with decreasing ...   more details



  1. Computational

    Wiktionary Computational may refer to Computer Computational algebra Computational Aeroacoustics Computational and Information Systems Laboratory Computational and Systems Neuroscience Computational archaeology Computational auditory scene analysis Computational biology Computational biomodeling Computational Center for Nanotechnology Innovations Computational chemical methods in solid state physics Computational chemistry Computational Chemistry Grid Computational Chemistry List Computational complexity of mathematical operations Computational complexity theory Computational creativity Computational cybernetics Computational Diffie Hellman assumption Computational Diffie Hellman problem Computational economics Computational electromagnetics Computational Engineering Computational epidemiology Computational epigenetics Computational epistemology Computational finance Computational fluid dynamics Computational forensics Computational formula for the variance Computational gene Computational genomics Computational geometry Computational Geometry Algorithms Library Computational geophysics Computational grid Computational group theory Computational hardness assumption Computational humor Computational indistinguishability Computational informatics Computational immunology Computational intelligence Computational Intelligence and Machine Learning Portal Computational Intensive Workload Computational intractability Computational irreducibility Computational journalism Computational learning theory Computational lexicology Computational linguistics Computational Linguistics journal Computational lithography Computational logic Computational magnetohydrodynamics Computational mathematics Computational matrix algebra Computational mechanics Computational Mechanics journal Computational model Computational modeling Computational Molecular Docking Computational musicology Computational neuroanatomy Computational neuroethology Computational neurogenetic modeling Computational neuroscience ...   more details



  1. Assumption

    wiktionary assumption In logic an assumption is a proposition that is taken for granted, as if it were truth true based upon presupposition without preponderance of the facts. An assumption that is considered to be self evident or otherwise fundamental is called an axiom . In religion, an assumption ... earth to heaven . Assumption of Mary , a religious account of the taking up of Mary into heaven Assumption of Moses , a Jewish apocryphal pseudepigraphical work of uncertain date and authorship Assumption may also refer to In logic, more specifically in the context of natural deduction systems, an assumption is a proposition that may be used to prove further propositions, in the expectation that the assumption ... model ling can be used to map the outcome of different assumptions on the system being modelled. Assumption ... and becomes directly liable for policy claims In real property law , an assumption is the mortgage loan mortgage transfer from the seller to the buyer In business planning and business plans, an assumption ... or plans of an organization Assumption Poker , a fictional type of poker variation, using Tarot cards. It appears in the novel Last Call by Tim Powers . Concepts Responsibility assumption , a doctrine ... responsibility for the events and circumstances that befall them in their life Locations Assumption, Alberta , Canada Assumption, Illinois , USA Assumption, Ohio , USA Assumption Cathedral disambiguation Assumption Island , Seychelles Assumption Parish , Louisiana, USA L Assomption River , Quebec, Canada Schools Assumption Antipolo , Philippines Assumption Junior Senior High School , Cold Lake, Alberta Assumption High School Indiana Assumption High School Davenport, Iowa Assumption High School Louisville, Kentucky Assumption High School Louisiana , Napoleonville, Louisiana Assumption Iloilo , Iloilo City, Philippines Assumption College , Worcester, Massachusetts Assumption Preparatory School , Worcester, Massachusetts Assumption Secondary School , Burlington, Ontario Assumption College ...   more details



  1. Hardness scales

    Hardness scales may refer to Methods of measuring mineral hardness Mohs scale of mineral hardness The Vickers hardness test The Brinell scale The Janka hardness test The Rockwell scale Hardness scales may also refer to deposits formed by hard water . Disambig ...   more details



  1. Hardness of approximation

    In computer science , hardness of approximation is a field that studies the algorithmic complexity of finding near optimal solutions to optimization problem s. It complements the study of approximation algorithm s by proving, for certain problems, a limit on the factors with which their solution can be efficiently approximated. Typically such limits show a factor of approximation beyond which a problem becomes NP hard , implying that finding a polynomial time approximation for the problem is impossible unless NP P . Some hardness of approximation results, however, are based on other hypotheses, a notable one among which is the unique games conjecture . Since the early 1970s it was known that many optimization problems could not be solved in polynomial time unless NP P , but in many of these problems the optimal solution could be efficiently approximated to a certain degree. In the early 1990s, with the development of PCP complexity PCP theory, it became clear that there is a limit to the approximability of many of these optimization problems for many optimization problems there is a threshold beyond which they are NP hard to approximate. Hardness of approximation theory deals with studying the approximation threshold of such problems. Examples For an example of an NP hard optimization problem that is hard to approximate, see set cover . See also PCP theorem Further reading http www.cs.berkeley.edu luca pubs inapprox.ps Survey, a good starter by Luca Trevisan External links http www.cs.washington.edu education courses 533 05au CSE 533 The PCP Theorem and Hardness of Approximation, Autumn 2005 , syllabus from the University of Washington , Venkatesan Guruswami and Ryan O Donnell Category Computational complexity theory Category Mathematical optimization comp sci theory stub ...   more details



  1. Indentation hardness

    Indentation hardness tests are used to determine the hardness of a material to deformation. Several such tests ... can be performed on a macroscopic or microscopic scale. When testing metals, indentation hardness correlates ... held Rockwell hardness testers. ref http www.springerlink.com content q86642448t84g267 Correlation of Yield Strength and Tensile Strength with Hardness for Steels , E.J. Pavlina and C.J. Van Tyne, Journal of Materials Engineering and Performance, Volume 17, Number 6 December, 2008 ref Material hardness ... material hardness by indenting a material with an impression have been developed to determine such properties. Hardness measurements quantify the resistance of a material to plastic deformation. Indentation hardness tests compose the majority of processes used to determine material hardness, and can ... have forces less than convert 2 N abbr on . Hardness, however, cannot be considered to be a fundamental ... , 162 168. ref As such, hardness can only offer a comparative idea of the material s resistance to plastic deformation since different hardness techniques have different scales. The main source ... experimentally determined through strainless hardness tests that the effect is minimal with smaller ... on the hardness measurement, as long as the indentation is large compared to the surface roughness. This proves to be useful when measuring the hardness of practical surfaces. It also is helpful ... is annealed it will sink in around the indentation. Both of these effects add to the error of the hardness measurement. ref Tabor, p. 15. ref The equation based definition of hardness is the pressure applied over the contact area between the indenter and the material being tested. As a result hardness ...  kgf or more. There are various macroindentation tests, including Vickers hardness test HV , which has one of the widest scales Brinell hardness test HB Knoop hardness test HK , for measurement over small areas Janka hardness test , for wood Meyer hardness test Rockwell scale Rockwell ...   more details



  1. Carbonate hardness

    Merge Carbonate alkalinity date November 2011 Wikify date October 2010 Carbonate hardness , or carbonate alkalinity is a measure of the alkalinity of water caused by the presence of carbonate CO sub 3 sub sup 2 sup and bicarbonate HCO sub 3 sub sup sup anions . It is usually expressed either as parts per million Parts per million ppm or Gram per litre mg L , or in degrees KH from the German Karbonathä rte . One German degree of carbonate hardness dKH corresponds to the carbonate and bicarbonate ions found in a solution of approximately 17.848 milligrams of calcium carbonate CaCO sub 3 sub per litre of water 17.848 ppm . Both measurements mg L or KH are usually expressed as CaCO sub 3 sub &ndash meaning the concentration of carbonate expressed as if calcium carbonate were the sole source of carbonate ions. Bicarbonate ions only contribute half as much carbonate hardness as carbonate ions, so bicarbonates that are present in the water are converted to an equivalent concentration of carbonates when determining KH. For example An aqueous solution containing 120  mg Sodium Bicarbonate NaHCO sub 3 sub baking soda per litre of water will contain 1.4285 mmol L of bicarbonate, since the molar mass of baking soda is 84.007 g mol. This is equivalent in carbonate hardness to a solution containing 0.71423  mmol L of carbonate, or 71.485  mg L of calcium carbonate molar mass 100.09 g mol . Since one degree KH 17.848  mg L CaCO sub 3 sub , this solution has a KH of 4.0052 degrees. The term carbonate hardness is also sometimes used as a synonym for Hard water Temporary hardness temporary hardness , in which case it refers to that portion of hard water that can be water softening removed by processes such as boiling or lime softening , and then separation of water from the resulting precipitate. ref cite web title Lime Softening url http water.me.vccs.edu concepts softeninglime.html ... External links http www.thekrib.com Plants CO2 hardness larryfrank.html Water Hardness definitions ...   more details



  1. The Hardness of the World

    Infobox Album Name The Hardness Of The World Type Studio Artist Slave band Slave Cover Released 1977 Recorded 1977 small at House Of Music, West Orange, New Jersey small Genre Soul music Soul Funk music Funk Length Label Cotillion Records Producer Jeff Dixon Slave band Slave Last album Slave Slave album Slave br 1977 This album The Hardness Of The World br 1977 Next album The Concept br 1978 The Hardness Of The World is the second album by United States American funk music funk band Slave band Slave . Reception Album ratings rev1 Allmusic rev1Score Rating 4 5 ref Allmusic class album id r49517 tab review label Slave The Hardness of the World Review first Craig last Lytle accessdate 30 August 2011 ref Released in 1977 the album led by the single The Party Song would chart at number twenty two on the Billboard Hot R&B Hip Hop Songs Hot Soul Singles chart. This would be the second album they would release in 1977. Track listing Life Can Be Happy 4 16 The Great American Funk Song 3 50 Can t Get Enough Of You 4 07 Baby Sinister 6 45 The World s On Hard 3 26 The Party Song 4 07 We Can Make Love 5 28 Volcano Rupture 6 23 Charts class wikitable Chart 1978 Peak br position Billboard 200 Billboard Pop Albums ref name allmusic albums Cite web url Allmusic class artist id p5452 charts awards billboard albums pure url yes title Slave US albums chart history publisher allmusic.com accessdate 2011 08 30 ref align center 67 Billboard Top R&B Hip Hop Albums Top Soul Albums ref name allmusic albums align center 31 Singles class wikitable style text align center rowspan 2 Year rowspan 2 Single colspan 3 Chart positions ref name allmusic singles Cite web url Allmusic class artist id p5452 charts awards billboard singles pure url yes title Slave US singles chart history publisher allmusic.com ... 74 References Reflist External links http www.discogs.com Slave The Hardness Of The World master 155496 Slave The Hardness Of The World at Discogs DEFAULTSORT Hardness of the World Category 1977 albums ...   more details



  1. Hardness comparison

    There are a large number of hardness testing methods available e.g. Vickers hardness test Vickers , Brinell scale Brinell , Rockwell scale Rockwell , Meyer hardness test Meyer and Leeb rebound hardness test Leeb . Although it is impossible in many cases to give an exact conversion, it is possible to give an approximate material specific comparison table e.g. for steel s. Hardness comparison table File HARDCOMP.PNG thumb 400px class wikitable Brinell HB br 10  mm Ball, 3000  kg load Vickers HV br 120  kg Rockwell C HRC br 120 degree cone 150  kg Rockwell B HRB br 1 16 ball 100  kg Leeb HLD ref H.Pollok, Umwertung der Skalen Conversion of Scales , Qualit t und Zuverl ssigkeit, Ausgabe 4 2008. ref 800 72 857 780 1220 71 850 760 1170 70 843 745 1114 68 837 725 1060 67 829 712 1021 66 824 682 940 65 812 668 905 64 806 652 867 63 799 626 803 62 787 614 775 61 782 601 746 60 776 590 727 59 770 576 694 57 763 552 649 56 751 545 639 55 748 529 606 54 739 514 587 53 120 731 502 565 52 119 724 495 551 51 119 719 477 534 49 118 709 461 502 48 117 699 451 489 47 117 693 444 474 46 116 688 427 460 45 115 677 415 435 44 115 669 401 423 43 114 660 388 401 42 114 650 375 390 41 113 640 370 385 40 112 635 362 380 39 111 630 351 361 38 111 621 346 352 37 110 617 341 344 37 110 613 331 335 36 109 605 323 320 35 109 599 311 312 34 108 588 301 305 33 107 579 293 291 32 106 572 285 285 31 105 565 276 278 30 105 557 269 272 29 104 550 261 261 28 103 542 258 258 27 102 539 249 250 ... Tables hardness.htm Hardness Conversion Table Brinell, Rockwell,Vickers Various steels http www.engineersedge.com hardness conversion.htm Rockwell to Brinell conversion chart Brinell ... 1 Struers hardness conversion table Vickers, Brinell, Rockwell B,C,D http www.westyorkssteel.com images rockwell scale conversion chart.pdf Brinell Hardness HB conversion chart N mm2, Brinell, Vickers, Rockwell C Category Hardness tests Category Comparisons ...   more details



  1. XDH assumption

    The external Diffie&ndash Hellman XDH assumption is a mathematic assumption used in elliptic curve cryptography . The XDH assumption holds that there exist certain subgroup s of elliptic curves which have useful properties for cryptography. Specifically, XDH implies the existence of two distinct Group mathematics groups math langle mathbb G 1, mathbb G 2 rangle math with the following properties The discrete logarithm problem DLP , the computational Diffie&ndash Hellman assumption computational Diffie&ndash Hellman problem CDH , and the computational co Diffie&ndash Hellman assumption computational co Diffie&ndash Hellman problem are all intractable in math mathbb G 1 math and math mathbb G 2 math . There exists an efficiently computable bilinear map pairing math e cdot, cdot mathbb G 1, mathbb G 2 rightarrow mathbb G T math . The decisional Diffie&ndash Hellman assumption decisional Diffie&ndash Hellman problem DDH is intractable in math mathbb G 1 math . The above formulation is referred to as asymmetric XDH . A stronger version of the assumption symmetric XDH , or SXDH holds if decisional Diffie&ndash Hellman assumption DDH is also intractable in math mathbb G 2 math . The XDH assumption ... for practical solutions to the decisional Diffie&ndash Hellman assumption DDH problem. These groups ... encryption Elgamal within a GDH group. Because the DDH assumption holds within at least one of a pair ... assumption may hold in certain subgroups of MNT curve MNT elliptic curves. This notion was first ... the efficiency of a signature scheme. The assumption was formally defined by Ballard, Green, de Medeiros .... Evidence for the validity of this assumption is the proof by Verheul 2001 and Galbraith and Rotger ... to solve the DDH problem in elliptic curve groups, it is believed that the DDH assumption therefore ... citation.cfm?id 647086.715689 Category Asymmetric key cryptosystems Category Computational hardness assumptions ...   more details



  1. Assumption University

    Assumption University may refer to Assumption University Windsor Assumption University Thailand University of the Assumption , Philippines schooldis Long comment to avoid being listed on short pages de Assumption University nl Assumption University ...   more details



  1. Meyer hardness test

    Image Meyer hardness test vs brinell hardness test.png thumb 400px This graph shows the differences between the Brinell hardness test and the Meyer hardness test. Notice that the Brinell test can report the same hardness value for a given specimen twice depending on the load. The Meyer hardness test is a rarely used hardness test based upon projected area of an impression. This is a more fundamental measurement of hardness than other hardness tests which are based on the surface area of an indentation. The principle behind the test is that the mean pressure required to test the material is the measurement of the hardness of the material. The mean pressure is calculated by dividing the load by the projected area of the indentation. The result is called the Meyer hardness, which has units of Pascal pressure megapascals MPa . ref name kts Citation title Hardness Testing url http www.keytometals.com page.aspx?ID CheckArticle&site kts&NM 140 accessdate 2008 10 07 . ref An advantage of the Meyer test is that it is less sensitive to the applied load, especially compared to the Brinell scale Brinell hardness test . For cold work ed materials the Meyer hardness is relatively constant and independent of load, whereas for the Brinell hardness test it decreases with higher loads. For Annealing metallurgy anneal ed materials the Meyer hardness increases continuously with load due to strain hardening. ref name kts Based on Meyer s law hardness values from this test can be converted into Brinell scale Brinell hardness values, and vice versa. ref Tabor, p. 10. ref See also multicol Brinelling Hardness comparison Knoop hardness test multicol break Leeb Rebound Hardness Test Rockwell scale Vickers hardness test multicol end References reflist Bibliography Citation last Tabor first David title The Hardness of Metals publisher Oxford University Press year 2000 url http books.google.com ?id b 9LdJ5FHXYC isbn 0198507763 . Category Hardness tests mech engineering stub ...   more details



  1. Barcol hardness test

    The Barcol hardness test characterizes the indentation hardness of materials through the depth of penetration of an indentor, loaded on a material sample and compared to the penetration in a reference material. The method is most often used for composite material s such as reinforced thermoset thermosetting resin s or to determine how much a resin or plastic has curing chemistry cured . The test complements the measurement of glass transition temperature , as an indirect measure of the degree of cure ... Colman inventor Walter Colman as a hand held, portable means of assessing the hardness of a material ... of checking the hardness of rivets due to concerns that aircraft could be sabotaged by replacing ... author Bennett, Robert B accessdate 2008 06 15 publisher Barber Colman News ref The hardness of the material ... to be read on a dial. ref name B C News Operation The Barcol hardness test is generally used on soft materials such as rigid plastics. It measures hardness based on indentation of a sharp point with a flat ... Shore hardness Shore D hardness however the Shore D indentor has a round tip. ref name Plastics ... and Processes A Concise Encyclopedia title Barcol Hardness url http books.google.com books?id oe5YJmRmxQMC&pg PA52&dq Barcol Hardness test&sig zhZZTpbsomXDcZJMIGPYTTR0Ysk accessdate 2008 02 10 publisher John Wiley and Sons ref Barcol hardness is not a valid hardness measure for curved surfaces. ref name NHML cite web url http nhml.com resources NHML Hardness Testing.php title NHML Resources Hardness ... The governing standard for the Barcol hardness test is ASTM D 2583. ref name Plastics Barcol hardness ... of 60B is roughly equivalent to a Shore hardness of 80D or a Rockwell hardness M100. ref name ... Hardness of Rigid Plastics by Means of a Barcol Impressor . ASTM International . Revision as of 2007 03 01 ref See also Brinell hardness test Knoop hardness test Rockwell scale Shore durometer Vickers hardness test Hardness comparison References Reflist Category Hardness tests ...   more details



  1. Church of the Assumption

    The Church of the Assumption may refer to tocright Bulgaria Church of the Assumption Uzundzhovo Czech Republic Church of the Assumption of the Virgin Mary Most Church of the Assumption of Our Lady and Saint John the Baptist , Kutn Hora Haiti Cathedral of Our Lady of the Assumption, Port au Prince Ireland Church of the Assumption, Booterstown Latvia Assumption of Our Lady Church, Bolder ja Malaysia Church of the Assumption Penang Mexico Cathedral of Our Lady of the Assumption, Oaxaca Poland Church of the Assumption Klodzko Slovakia Assumption of Mary Church Ro ava Slovenia Church of the Assumption of the Virgin Mary and Roch Jesenice United States Holy Assumption of the Virgin Mary Church , Kenai, Alaska St. Mary s Assumption Church New Orleans, Louisiana Saint Mary of the Assumption Church, Rectory, School and Convent , Brookline, Massachusetts Assumption of the Blessed Virgin Mary Church , Detroit, Michigan Church of the Assumption Houghton Township, Michigan Church of the Assumption Phoenix, Michigan Church of the Assumption Saint Paul, Minnesota Church of the Assumption Nashville, Tennessee St. Mary of the Assumption Church , Fort Worth, Texas St. Mary s Church of the Assumption , Praha, Texas See also Our Lady of the Assumption Church disambiguation Assumption Cathedral disambiguation Dormition Church disambiguation Disambig church bg cs Kostel Nanebevzet Panny Marie de Maria Himmelfahrt Kirche es Iglesia de la Asunci n it Chiesa di Santa Maria Assunta pt Igreja de Nossa Senhora da Assun o sk Kostol Nanebovzatia Panny M rie ...   more details



  1. Leeb rebound hardness test

    Image Application Picture Equotip.jpg thumb 300px A Leeb rebound hardness test The Leeb rebound hardness test is one of the four most used method for testing metal hardness . This portable method is mainly ... 2009 History The Leeb rebound hardness test method was developed in 1975 by Leeb and Brandestini at Proceq SA to provide a portable hardness test for metals. It was developed as an alternative to the unwieldy and sometimes intricate traditional hardness measuring equipment. The first Leeb rebound ... due to the wide circulation of the Equotip product. Traditional hardness measurements, e.g. according to Rockwell scale Rockwell , Vickers hardness test Vickers and Brinell scale Brinell , are stationary ... simplifies processes and saves costs. ref name T. Mennicke, 2008 R. T. Mennicke, Equotip Metal Hardness ... on well defined physical indentation hardness tests. Very hard indenters of defined geometries ..., such as the indentation depth in the Rockwell method, are recorded to give measures of hardness. ref name Kunststoffen 2007 K. Herrmann et. al., H rtepr fung an Metallen und Kunststoffen Hardness tests ..., the hardness value is derived from the energy loss of a defined impact body after impacting on a metal ... i sub is quoted in the Leeb rebound hardness unit HL. ref name T. Mennicke, 2008 ref M. Tietze, M. Kompatscher, Predicative Hardness Testing for Production Control and Materials Design , IMEKO TC5 2002 ... steel casting with a Leeb hardness of 600 HLD. By comparison, a Brinell indentation on the same material is 3  mm hardness value 400 HBW 10 3000 , with a standard compliant measuring time of 15 seconds ... force, diverse impact devices and hardness units are distinguished, e.g. Equotip impact device D with hardness unit HLD Equotip impact device G with hardness unit HLG Generally, impact device ... and test loads in Rockwell e.g. HRA, HRB, HRC , Brinell and Vickers. Leeb hardness results in HL are often converted to the traditional hardness scales HRC, HB and HV mainly for convention reasons ...   more details



  1. Vickers hardness test

    Image Vickers tester.png thumb A Vickers hardness tester The Vickers hardness test was developed in 1921 ... Brinell method to measure the hardness of materials. ref R.L. Smith & G.E. Sandland, An Accurate Method of Determining the Hardness of Metals, with Particular Reference to Those of a High Degree of Hardness ... test is often easier to use than other hardness tests since the required calculations are independent of the size of the indenter, and the indenter can be used for all materials irrespective of hardness. The basic principle, as with all common measures of hardness, is to observe the questioned ... for all metal s and has one of the widest scales among hardness tests. The unit of hardness given by the test is known as the Vickers Pyramid Number HV or Diamond Pyramid Hardness DPH . The hardness ..., which also has units of pascals. The hardness number is determined by the load over the surface area of the indentation and not the area normal to the force, and is therefore not a pressure. The hardness ... be seen in conjunction with the experimental methods and hardness scale used. Implementation Image Vickers path 2.svg thumb Vickers test scheme Image Case hardened steel vickers hardness test.png thumb An indentation left in case hardened steel after a Vickers hardness test. Notice the difference in length ... that the ideal size of a Brinell hardness test Brinell impression was 3 8 of the ball diameter ... that the hardness value obtained on a homogeneous piece of material remained constant, irrespective ... are applied to a flat surface, depending on the hardness of the material to be measured. The HV ... of HV are then kilograms force per square millimeter kgf mm . To calculate Vickers hardness number ... unit newtons and d is millimeters. Vickers hardness numbers are reported as xxxHVyy , e.g. 440HV30 , or xxxHVyy zz if duration of force differs from 10 s to 15 s, e.g. 440Hv30 20, where 440 is the hardness number, HV gives the hardness scale Vickers , 30 indicates the load used in kg. 20 indicates ...   more details



  1. Assumption Cathedral

    Assumption Cathedral or Dormition Cathedral Russian Cathedral of the dormition or Uspenski Cathedral may refer to a number of Cathedral Cathedral churches consecrated to the Dormition of the Theotokos in the Orthodox tradition and Assumption of Mary in the Roman Catholic tradition Mother churches of Russia and Ukraine The Dormition Cathedral, Vladimir , aka Assumption Cathedral in Vladimir 1158 89 the mother church of Russia from the 12th to the 15th century, the model for all subsequent churches of that name The Dormition Cathedral, Moscow , aka Assumption Cathedral in the Moscow Kremlin 1475 79 Other in Russia and Ukraine The Cathedral of the Dormition Pechersk Lavra , aka Assumption Cathedral in Kiev, Ukraine 1073 78, rebuilt 1640s, destroyed 1941, rebuilt 1998 The Assumption Cathedral in Rostov date of construction disputed, the early 16th century being the most likely The Assumption Cathedral in Ryazan 1693 99 The Cathedral of the Assumption, Smolensk Assumption Cathedral in Smolensk 1677 79, 1732 40 The Assumption Cathedral in Tula 1762 64 The Assumption Cathedral in Volodymyr Volynskyi 1160, collapsed 1829, rebuilt 1900 The Assumption Cathedral in Yaroslavl 1640s, rebuilt 2000s The Assumption Cathedral in Zvenigorod 1399 The Assumption Cathedral, Kharkiv Assumption Cathedral in Kharkiv 1777 The Assumption Cathedral in Pochayiv Lavra 1783 The Assumption Cathedral in Dmitrov 1509 21 The Assumption Cathedral in Omsk 1893 1935, 2000s The Assumption ... Cathedral, Varna, Bulgaria Roman Catholic churches The Assumption Cathedral, Bangkok , principal ... Tuam Cathedral , aka Cathedral Church of the Assumption of the Blessed Virgin Mary, Tuam, County Galway, Ireland Cathedral of the Assumption Louisville in Louisville, Kentucky Cathedral of Saint Mary of the Assumption in San Francisco, California Cathedral of the Assumption of the Virgin formal name ... Inventory of Cultural Property of National and Regional Significance See also Our Lady of the Assumption ...   more details



  1. Roll hardness tester

    A roll hardness tester is a device to measure the roll hardness, hardness profile and hardness variation of paper rolls. Method In the preparation phase, the plunger, guide bar and guide disk are pushed forward by the compression spring. At the end of the movement the hammer mass is hooked by the pawl. During the loading phase the hammer is pushed towards the surface in a controlled movement. The hammer mass remains locked in place by the pawl. This has the effect of stretching the impact spring to put it under tension. Impact Rebound At the very end of the movement, the pawl spring releases the hammer mass. The impact spring contracts causing the hammer mass to strike against the plunger. This is the impact. The hammer mass then rebounds back to the body of the hammer and distance travelled is recorded on the scale. The rebound distance depends directly on the hardness of the roll under test A softer roll will absorb more of the impact energy and the rebound distance will be less. A harder roll will reflect more of the impact energy and the rebound distance will increase. Standards TAPPI T 834 om 07 Determination of containerboard roll hardness TAPPI TIP 1004 01 TAPPI Roll Number for inventory tracking systems and bar codes Application Roll hardness is one of the most important parameter when deciding whether a paper roll is good or bad. A roll that is wound too softly can go out of round when handled. A roll that is wound too hard, on the other hand, can crack during transportation. ref name R.Duane Smith Black Clawson Converting Machinery, The Art of Winding Good Rolls . ref These variations are difficult to detect. Above all, it is typically the variation in hardness across a given roll that relates most directly to such converting issues with soft edges being perhaps the biggest contributor. ref name TAPPI Standard TAPPI Standard T 834 om 07 ref See also Paper mill Pulp paper References Reflist Category Measuring instruments Category Hardness tests ...   more details



  1. Knoop hardness test

    The Knoop hardness test IPA en k nu p is a microhardness test a test for mechanical hardness used particularly for very brittle materials or thin sheets, where only a small indentation may be made for testing purposes. A pyramid al diamond point is pressed into the polished surface of the test material with a known force, for a specified dwell time, and the resulting indentation is measured using a microscope . The geometry of this indenter is an extended pyramid with the length to width ratio being 7 1 and respective face angles are 172 degrees for the long edge and 130 degrees for the short edge. The depth of the indentation can be approximated as 1 30 of the long dimension. ref http www.gordonengland.co.uk hardness microhardness.htm Microhardness Test , Surface Engineering Forum ref The Knoop hardness HK or KHN is then given by the formula math HK textrm load mbox kgf over textrm impression area mbox mm 2 P over C pL 2 math where L length of indentation along its long axis C sub p sub correction factor related to the shape of the indenter, ideally 0.070279 P load HK values are typically in the range from 100 to 1000, when specified in the conventional units of g sub f sub mm sup 2 sup . The SI unit, pascal unit pascal s, are sometimes used instead 1  kg sub f sub mm sup 2 sup 9.80665 MPa. The test was developed by Frederick Knoop ref F. Knoop, C.G. Peters and W.B. Emerson, A Sensitive Pyramidal Diamond Tool for Indentation Measurements, Journal of Research of the National ... enamel 343 Quartz 820 Silicon carbide 2480 Diamond 7000 See also multicol Vickers hardness test Ceramography Microindention hardness and toughness Knoop hardness of ceramics multicol break Leeb Rebound Hardness Test Meyer hardness test multicol end References reflist External links http www.efunda.com units hardness convert hardness.cfm?cat Steel&HD HK efunda http web.archive.org web 20080113233200 http www.lib.umich.edu dentlib Dental tables Knoophard.html Dental hardness tables Category Hardness ...   more details



  1. Assumption Iloilo

    Infobox school name Assumption Iloilo image imagesize alt caption motto established 1910 opened February 27, 1912 type Catholic school type label district grades superintendent principal viceprincipal viceprincipal label enrollment faculty ceeb campus type campus size mascot newspaper colors location General Luna St., Iloilo City , country Philippines coordinates coord 10.702456 122.565582 display inline,title website Assumption Iloilo also known as AC or the Assumption Convent is a Catholic school in General Luna St., Iloilo City , Philippines . It is a Single sex education girls only high school, though it offers preschool and primary education for both sexes. It was founded by the Sisters of the Assumption in 1910. History The Nun Sisters of the Religious of the Assumption first came to the Philippines in 1892 at the request of Maria Christina of Austria Queen Maria Cristina of Spain . They established the Superior Normal School for Women Teachers in 1893, one of the first schools for women in the Philippines. However, with the end of the Spanish colonial rule over the Philippines in 1898, the school eventually closed and the Sisters returned to Spain. ref name assumption cite web url http www.assumptionphil.org beginnings.htm title Our Beginnings publisher Religious of the Assumption, Philippines Thailand Province, http www.assumptionphil.org accessdate March 13, 2011 ref In 1904 ... to Pope Pius X . ref name assumption They reestablished several schools, among them was the Assumption College Philippines Assumption College of Makati and Assumption Iloilo in 1910. ref name centennial ... title Assumption Iloilo s Centennial Free Medical & Dental Clinic author date ... later. School Program Assumption Iloilo offers Preschool education Preschool and Elementary school ... High school Philippines First to Fourth Year is exclusive for girls. See also Religious of the Assumption References reflist DEFAULTSORT Assumption Iloilo Category Roman Catholic elementary schools ...   more details



  1. Tablet hardness unit

    The units of hardness for tablets follows standards for materials testing the International System of Units SI from Le Syst me International d Unit s 1 4 . Kilogram kg The kilogram is recognized by the SI system as the primary unit of mass. Newton N The Newton is the SI unit of force the standard for tablet hardness testing. 9.807 Newtons 1 kilogram. Pound lb Technically a unit of mass but can also be used for force and should be written as pound force or lbf in this case. Sometimes used for tablet strength testing in North America, but it is not an SI unit. 1 kilogram 2.204 pounds. Historically, tablet hardness testing evolved using units derived from specific instrument readings. Kilopond kp Not to be confused with a pound. A unit of force also called a kilogram of force. Still used today in some applications, but not recognized by the SI system. 1 kilopond 1 kgf. Strong Cobb SC The Strong Cobb unit is a legacy of one the first tablet hardness testing machines. ref http www.google.com patents?id kq9MAAAAEBAJ&printsec abstract&zoom 4&source gbs overview r&cad 0 v onepage&q&f false Tablet Hardness Testing Machine , cite patent US 2645936 ref Although the SC is arbitrary, it was recognized as the international standard from the 1950s to the 1980s. 1.4 Strong Cobbs are approximately 1 kg 5 . Notes reflist Additional references Russ Rowlett, http www.unc.edu rowlett units index.html How Many? A dictionary of units and measurements http www.bipm.fr enus 3 SI The International System of Units SI , Bureau International des Poids et Mesures J.E. Rees & P. J. Rue, Work Required to Cause Failure of Tablets in Diametrical Compression , Aston University, Birmingham, UK Drug Development & Industrial Pharmacy. 4 2 131 156 1978 American Society for the Testing of Materials ASTM , Designation E4 07, Standard Practices for Force Verification of Testing Machines . www.astm.org McCallum ... tablet hardness testers. Journal of the American Pharmaceutical Association, 44 83 85. doi 10.1002 ...   more details



  1. Academy of the Assumption

    Image Stjudechurch.jpg thumb right Old Assumption Chapel , now St. Jude Melkite Catholic Church built in 1946 of Indiana Bedford stone Academy of the Assumption was a Catholic all girls school that was located on Biscayne Bay in Miami , Florida . Built in 1943 and closed in 1976, it was run by the Religious of the Assumption . The school s last principal was Sr. Therese Margaret Duross R.A. http www.assumptionsisters.org archived news 061007MiamiAlumnae.htm . After being closed, the facilities were sold. Most buildings have since been demolished, replaced by luxury high rise condominiums that dot the area s skyline. However, some buildings are still standing and in use. The Assumption Chapel remains active, now a part of St. Jude Melkite Catholic Church . Notable Alumni Cristina Saralegui 66 References http www.assumptionsisters.org news archives.html Sisters of the Assumption article The Miami News , Liquidation Sale Clears Out Academy Of The Assumption by Eliott Rodriguez , July 17, 1978, Page 4A. The Miami News, Condo To Tower 41 Stories , by Larry Birger, July 25, 1979, Page 1A The Miami Daily News , Chapel Cornerstone is Laid at Academy , May 3, 1946, Page 1B. Category Defunct Roman Catholic schools in the United States Category Roman Catholic Archdiocese of Miami Category Defunct schools in Florida Florida school stub ...   more details



  1. Cluster assumption

    Orphan date October 2011 References date November 2011 The cluster assumption is a type of data modeling used in machine learning specifically in Supervised learning and Semi supervised learning . It states that if points are in the same cluster, they are likely to be of the same class. ref O. Chapelle and B. Sch lkopf and A. Zien, Semi Supervised Learning, MIT Press, 2006 ref There may be multiple clusters forming a single class. Introduction The cluster assumption is implicitly assumed in many machine learning algorithms such as the K nearest neighbor algorithm K nearest neighbor classification algorithm and the K means clustering K means clustering algorithm . As the word likely appears in the definition, there is no clear border differentiating whether the assumption does hold or does not hold. In contrast the amount of adherence of data to this assumption can be quantitatively measured. Properties The cluster assumption is equivalent to the Low density separation assumption which states that the decision boundary should lie on a low density region. To prove this, suppose the decision boundary crosses one of the clusters. Then this cluster will contain points from two different classes, therefore it is violated on this cluster. Notes Reflist Category Data modeling ...   more details




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