text: T-Shirtshock Polo Uomo Nero OLDENG00596 Neutron Symbol: Amazon.it: Abbigliamento Selezione delle preferenze relative ai cookie Utilizziamo cookie e altre tecnologie simili per migliorare la tua esperienza di acquisto, per fornire i nostri servizi, per capire come i nostri clienti li utilizzano in modo da poterli migliorare e per visualizzare annunci pubblicitari. This isotope has half-life of 55.6 seconds.It undergoes negative beta decay through its two main branches with emission of 2.6 MeV and 8 MeV beta particles. Neutron definition, an elementary particle having no charge, mass slightly greater than that of a proton, and spin of ½: a constituent of the nuclei of all atoms except those of hydrogen. Neutronium is an obsolete term for a theoretical element composed mainly of neutrons. The symbols D and T are sometimes used for deuterium and tritium. Pick your favorite designs on our Proton Electron Neutron Symbol Stainless Steel Flasks. Lots of different size and color combinations to choose from. Uranium is a chemical element with atomic number 92 which means there are 92 protons and 92 electrons in the atomic structure. The neutron number, symbol N, is the number of neutrons in a nuclide. Solution: A The element with 82 protons (atomic number of 82) is lead: Pb. https://www.wikihow.com/Find-the-Number-of-Protons,-Neutrons,-and-Electrons The number on the bottom left corner is the atomic number, which tells you the number of protons. How many Neutron Mass is 391 Kilograms? Find out with Milligram to Neutron Mass conversion table. Symbol: n See more. Free Returns High Quality Printing Fast Shipping The difference between the neutron number and the atomic number is known as the neutron excess : D = N - Z = A - 2 Z . Shop Proton Electron Neutron Symbol Pet Apparel from CafePress. However, some even neutron numbers also have only one stable isotope; these numbers are 2 (4He), 4 (7Li), 84 (142Ce), 86 (146Nd) and 126 (208Pb).[2]. Neutron number, N = A-Z. Previous question Next question Transcribed Image Text from this Question. The number on the upper left corner is the mass number, which is equal to the neutrons and protons added together. The term "neutronium" was coined in 1926 by Andreas von Antropoff for a conjectured form of matter made up of neutrons with no protons or electrons, which he placed as the chemical element of atomic number zero at the head of his new version of the periodic table. Nuclides that have the same neutron excess are called isodiaphers.[1]. Download Atom neutron stock photos. Neutron emission usually happens from nuclei that are in an excited state, such as the excited 87 Kr* produced from the beta decay of 87 Br. Atomic Number – Protons, Electrons and Neutrons in Chlorine. 2 H, or deuterium (D), is the other stable isotope of hydrogen. No stable nuclides have neutron number 19, 21, 35, 39, 45, 61, 89, 115, 123, and ≥ 127. Isotope notation, also known as nuclear notation, is important because it allows us to use a visual symbol to easily determine an isotope's mass number, atomic number, and to determine the number of neutrons and protons in the nucleus without having to use a lot of words. it's neutral, because 0 is neither positive nor negative. The symbol for neutron is simply n because it is neutral in charge. Beta-delayed Neutron Emission – Delayed Neutrons Precursors of Delayed Neutrons. What is the MOOD in the story of The Aged Mother? While it's common to write nuclear symbols with the atomic mass—the sum of the number of protons and neutrons—as a superscript and atomic number (the number of protons) as a subscript, there's an easier way to indicate nuclear symbols. The symbol for neutron is n with a raised 0. Experts are waiting 24/7 to provide step-by … The material on this site can not be reproduced, distributed, transmitted, cached or otherwise used, except with prior written permission of Multiply. Illustration about Symbol and electron diagram for Mercury illustration. Shop Now! Neutrons do not have any net electric charge associated with them. x) Location: Lies inside the nucleus. baryon; nucleon; Derived terms All Rights Reserved. check_circle Expert Answer. Acquista T-Shirtshock Felpa Donna Cappuccio Nero OLDENG00596 Neutron Symbol spedizione gratuita resi gratuiti su prodotti idonei Neutron was discovered by Sir James Chadwick (A British physicist) and theorized by Ernest Rutherford. -1 Check out a sample Q&A here. It has no electric charge and a rest mass equal to 1.67493 × 10−27 kg—marginally greater than that of the proton but nearly 1,839 times greater than that of the electron. Want to see the step-by-step answer? For more information see "Neutron … Milligram to Neutron Mass converter online tool to convert Milligram to Neutron Mass. Expert Answer . Mass number (symbol A) is a sum of numbers of protons and neutrons. Atomic number (proton number) plus neutron number equals mass number : Z + N = A . The symbol for neutron is simply n because it is neutral in Compra [Neutron-Star] Snap-on Series plastica caso dura Guscio Protettivo Cassa Cover Case per Apple (5.5 inches!!!) Free Returns High Quality Printing Fast Shipping They do, however, have mass which is slightly greater in magnitude than that of a proton. Want to see this answer and more? Atomic Number – Protons, Electrons and Neutrons in Phosphorus. Why don't libraries smell like bookstores? Most odd neutron numbers have at most one stable isotope (exceptions are 1 (2H and 3He), 5 (9Be and 10B), 7 (13C and 14N), 55 (97Mo and 99Ru) and 107 (179Hf and 180mTa). How many Neutron Mass is 459 Kilograms? SPEDIZIONE GRATUITA su … Shop Neutron Symbol Racerback Racerback Tank Top designed by DetourShirts. I'll give 10 points to whoever can answer..... Is the nuclear symbol for electron 1= being top and 0 = being bottom like this 0 beta? Neutron cross sections are related to the geometric cross section of the target nucleus. Chlorine is a chemical element with atomic number 17 which means there are 17 protons in its nucleus.Total number of protons in the nucleus is called the atomic number of the atom and is given the symbol Z.The total electrical charge of the nucleus is therefore +Ze, where e (elementary charge) equals to 1,602 x 10-19 coulombs. Neutron Shielding 43 D is the dose rate with the shield D0 is the dose rate without the shield t is the shield thickness Nitrogen is a chemical element with atomic number 7 which means there are 7 protons in its nucleus.Total number of protons in the nucleus is called the atomic number of the atom and is given the symbol Z.The total electrical charge of the nucleus is therefore +Ze, where e (elementary charge) equals to 1,602 x 10-19 coulombs. Why a pure metal rod half immersed vertically in water starts corroding? Baryons are massive particles which are made up of three quarks in the standard model. Neutron number is rarely written explicitly in nuclide symbol notation, but appears as a subscript to the right of the element symbol. There are 6 stable nuclides and one radioactive primordial nuclide with neutron number 82 (82 is the neutron number with the most stable nuclides, since it is a magic number): barium-138, lanthanum-139, cerium-140, praseodymium-141, neodymium-142, and samarium-144, as well as the radioactive primordial nuclide xenon-136. For example, actinides with odd neutron number are usually fissile (fissionable with slow neutrons) while actinides with even neutron number are usually not fissile (but are fissionable with fast neutrons). For example, hydrogen has three isotopes, each with a single proton. How to convert 549 Milligram to Neutron Mass? Neutron Shielding Calculations The following equation (modified from one in from NBS Handbook 63) describes the effect of shield thickness on the neutron dose rate associated with a radioactive neutron source (e.g., AmBe). It was subsequently placed in the middle of several spiral representations of the periodic system for classifying the chemical elements, such as those of Charles Janet (1928), E. I. Emerson (1944), and John D. Clark (1950). How many Neutron Mass is 549 Milligrams? The neutron cross-section is variable and depends on: Target nucleus (hydrogen, boron, uranium, etc.) In order of increasing explicitness and decreasing frequency of usage: Nuclides that have the same neutron number but different proton numbers are called isotones. The Nuclide Notation The letter (s) in the middle is the symbol of the element. Although elements have a specific number of protons, atoms of the same element may have different numbers of neutrons and are termed isotopes. Give the symbol for (a) a neutron, (b) an alpha particle, (c) gamma radiation. SPEDIZIONE GRATUITA su ordini idonei Calculate the mass number of each isotope by adding together the numbers of protons and neutrons. The cross section for a given nuclear interaction is also dependent on other factors, such as the speed of the Looking for a way to discreetly hide you drink? Shop Neutron Symbol Cap designed by DetourShirts. The symbol for neutron is n with a raised 0. To signify that it's neutral, because 0 is neither positive nor negative. Posted By Steven Pomeroy On Date November 7, 2020 (via Sixty Symbols ) Featuring Professor Mike Merrifield from the University of Nottingham talking about neutron stars and pulsars. Question: Examine The Isotope Symbol Below. The atom consist of a small but massive nucleus surrounded by a cloud of rapidly moving electrons.The nucleus is composed of protons and neutrons.The total number of neutrons in the nucleus of an atom is called the neutron number of the atom and is given the symbol N. Neutron number plus atomic number equals atomic mass number: N+Z=A. The ordinary isotope of hydrogen, with no neutrons, is sometimes called protium. Therefore, cross sections are typically expressed in cm2 or barns(b) = 10-24 cm2. In a nucleus, a neutron stays with a proton in the center. Phosphorus is a chemical element with atomic number 15 which means there are 15 protons in its nucleus.Total number of protons in the nucleus is called the atomic number of the atom and is given the symbol Z.The total electrical charge of the nucleus is therefore +Ze, where e (elementary charge) equals to 1,602 x 10-19 coulombs. Unlike protons and electrons, which are electrically charged, neutrons have no charge—they are electrically neutral. The neutron interacts with normal matter through either the nuclear force or its magnetic moment. Commonly accepted symbols as per Baryon classification is n, n0 implicating the net zero charge for a neutron. That's why the neutrons in the diagram above are labeled $$n^0$$. Illustration of neutron, molecule, fundamental - 62879102 Symbol: n: Antiparticle: Neutron: Discovered: Bruce Cork (1956) Mass: 939.565 560 (81) MeV/c 2: Electric charge: 0: Magnetic moment +1.91 µ N: Spin 1 ⁄ 2: Isospin 1 ⁄ 2 Neutron number is primarily of interest for nuclear properties. To signify that What should Stephen do to maintain standards and ensure that all the guest rooms are serviced? How long will the footprints on the moon last? vi) Mass of 1 mole of neutron is nearly 1.0087 g. vii) Disintegration: Isolated neutron is unstable and disintegrates into electron, proton and neutrino. Atomic Number – Protons, Electrons and Neutrons in Calcium. 235 „U 92 O 92 0 143 235 0 327. Kilogram to Neutron Mass converter online tool to convert Kilogram to Neutron Mass. Atomic Number – Protons, Electrons and Neutrons in Nitrogen. Neutron definition, an elementary particle having no charge, mass slightly greater than that of a proton, and spin of ½: a constituent of the nuclei of all atoms except those of hydrogen. Hydrogen-1 has the smallest neutron number, 0. ; The mass number of the atom (M) is equal to the sum of the number of protons and neutrons in the nucleus. What is plot of the story Sinigang by Marby Villaceran? They are usually denoted by the symbol n or no. What are the ratings and certificates for The Wonder Pets - 2006 Save the Nutcracker? Chemical properties are primarily determined by proton number, which determines which chemical element the nuclide is a member of; neutron number has only a slight influence. The various species of atoms whose nuclei contain particular numbers of protons and neutrons are called nuclides. Additionally, N = A− Z Neutrons and protons are collectively referred to as nucleons, since they behave in a similar manner inside the nuclei of atoms. Only two stable nuclides have fewer neutrons than protons: hydrogen-1 and helium-3. neutron (plural neutrons) A subatomic particle forming part of the nucleus of an atom and having no charge; it is a combination of an up quark and two down quarks. Neutron Number. Acquista T-Shirt Uomo Nero OLDENG00596 Neutron Symbol spedizione gratuita resi gratuiti su prodotti idonei How to convert 391 Kilogram to Neutron Mass? Protons and neutrons determine the mass of an atom. The number of protons in the nucleus of the atom is equal to the atomic number (Z).The number of electrons in a neutral atom is equal to the number of protons. Each isotop has its own set of cross-sections. A proton is a subatomic particle, symbol p or p +, with a positive electric charge of +1e elementary charge and a mass slightly less than that of a neutron.Protons and neutrons, each with masses of approximately one atomic mass unit, are collectively referred to as "nucleons" (particles present in atomic nuclei). ix) Symbol: 0n1. Atomic number (proton number) plus neutron number equals mass number: Z + N = A. Deuterium. For more information see "Neutron … The symbol for the element is as shown below: (1) Z A E An example is neon, which has the element symbol Ne, atomic number 10 and mass number 20. Affordable and search from millions of royalty free images, photos and vectors. How much power is consumed by a 12-V incandescent lamp if it draws 150mA of current when lit? Copyright © 2020 Multiply Media, LLC. The symbol Nu was given as the symbol of the predicted radioactive element. The variants of the same chemical element with a different number of neutrons are called isotopes. The zero stands for "zero charge". It has a natural abundance … Neutron cross-sections constitute a key parameters of nuclear fuel. Protium is an isotope of hydrogen with zero neutrons, deuterium has one neutron, and tritium has two neutrons. Neutron is composed of one up quark and 2 down quark. Synonyms . Atomic number (proton number) plus neutron number equals mass number: Z + N = A.The difference between the neutron number and the atomic number is known as the neutron excess: D = N - Z = A - 2Z.. Neutron number is rarely written explicitly in nuclide symbol notation, but appears as a subscript to the right of the element symbol. The total number of neutrons in the nucleus of an atom is called the neutron number of the atom and is given the symbol N.Neutron number plus atomic number equals atomic mass number: N+Z=A.The difference between the neutron number and the atomic number is known as the neutron excess: D = N – Z = A – 2Z. iPhone 6+ Plus / 6S+ Plus [Labbra Marylin film star Lady Sex Symbol nero]. The mass of a neutroncan be roughly approximated to one atomic mass unit (often ab… Neutrons and Neutronium is an obsolete term for a theoretical element composed mainly of neutrons. What is the temperature in K of 0.0420 mole of gas at 16.3 psi and that occupies 981 mL? Compra [Neutron-Star] Snap-on Series plastica caso dura Guscio Protettivo Cassa Cover Case per Motorola Moto G 1 1ST Gen [Nature Symbols Arte tradizionale positivi]. Calcium is a chemical element with atomic number 20 which means there are 20 protons in its nucleus.Total number of protons in the nucleus is called the atomic number of the atom and is given the symbol Z.The total electrical charge of the nucleus is therefore +Ze, where e (elementary charge) equals to 1,602 x 10-19 coulombs. Show transcribed image text. Learn how and when to remove this template message, "The NUBASE2016 evaluation of nuclear properties", https://en.wikipedia.org/w/index.php?title=Neutron_number&oldid=982665459, Articles needing additional references from April 2011, All articles needing additional references, Creative Commons Attribution-ShareAlike License, This page was last edited on 9 October 2020, at 15:36. Boron is a chemical element with atomic number 5 which means there are 5 protons in its nucleus.Total number of protons in the nucleus is called the atomic number of the atom and is given the symbol Z.The total electrical charge of the nucleus is therefore +Ze, where e (elementary charge) equals to 1,602 x 10-19 coulombs. Personalize or create your own custom Flask! The element was suggested by Andreas von Antropoff in 1926 (before the neutron was officially discovered). Fluorine is a chemical element with atomic number 9 which means there are 9 protons and 9 electrons in the atomic structure.The chemical symbol for Fluorine is F. Fluorine is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions. Nuclear Symbol Shorthand . The difference between the neutron number and the atomic number is known as the neutron excess: D = N - Z = A - 2Z. This question hasn't been answered yet Ask an expert. The symbol of the neutron is n, n 0, or N 0. Find out with Kilogram to Neutron Mass conversion table. The number of protons, neutrons, and electrons in an atom can be determined from a set of simple rules. The IUPAC accepts the D and T symbols, but recommends instead using standard isotopic symbols (2 H and 3 H) to avoid confusion in the alphabetic sorting of chemical formulas. Nuclides that have the same mass number are called isobars. The chemical symbol for Uranium is U. Neutron Number and Mass Number of Uranium Mass numbers of typical isotopes of Uranium are 238, 235. n (symbol) Hypernyms . The number of neutrons in a nucleus is known as the neutron number and is given the symbol N. The total number of nucleons, that is, protons and neutrons in a nucleus, is equal to Z + N = A, where A is called the mass number. The neutron number, symbol N, is the number of neutrons in a nuclide. Who is the longest reigning WWE Champion of all time? Only 58 stable nuclides have an odd neutron number, compared to 194 with an even neutron number. How Smooth Is a Neutron Star? viii) Among all the elementary particles neutron is the heaviest and least stable. Neutron radiation is a form of ionizing radiation that presents as free neutrons.Typical phenomena are nuclear fission or nuclear fusion causing the release of free neutrons, which then react with nuclei of other atoms to form new isotopes—which, in turn, may trigger further neutron radiation. The neutron magnetic moment is the intrinsic magnetic dipole moment of the neutron, symbol μ n. Protons and neutrons, both nucleons, comprise the nucleus of atoms, and both nucleons behave as small magnets whose strengths are measured by their magnetic moments. Free Returns High Quality Printing Fast Shipping Atomic Number – Protons, Electrons and Neutrons in Boron. Neutrons are subatomic particles that are one of the primary constituents of atomic nuclei. helpo!!!! The number of neutrons in a given element, however, can vary. How to convert 459 Kilogram to Neutron Mass? The symbol Nu was given as the symbol of the predicted radioactive element. Lots of different size and color combinations to choose from. What Is The Number Of Neutrons For The Isotope Shown? The mass of a neutron is slightly greater than the mass of a proton, which is 1 atomic mass unit $$\left( \text{amu} \right)$$. Symbol: n See more. Free Returns High Quality Printing Fast Shipping When we write the symbol for an atom, we can place its mass number at the top left and its atomic number at the bottom left. See Answer. Chemical Symbol for Fluorine. The element was suggested by Andreas von Antropoff in 1926 (before the neutron was officially discovered). When did organ music become associated with baseball? Find out with Kilogram to Neutron Mass conversion table. Kilogram to Neutron Mass converter online tool to convert Kilogram to Neutron Mass. No odd-neutron-number isotope is the most naturally abundant isotope in its element, except for beryllium-9 (which is the only stable beryllium isotope), nitrogen-14, and platinum-195. charge. Neutron, neutral subatomic particle that is a constituent of every atomic nucleus except ordinary hydrogen. Shop Neutron Symbol Framed Tile designed by DetourShirts. Give the symbol of each isotope with the mass number as the superscript and the number of protons as the subscript, both written to the left of the symbol of the element. Browse a huge selection of shirts for dogs of all sizes. Neutron cross-sections must be calculated for fresh fuel assemblies usually in two-Dimensional models of the fuel lattice. symbol of a neutron tags : Atom Logos Download Free Vector Art, Stock Graphics & Images , Atom Part On White Bakground. Every nuclide has a chemical element symbol (E) as well as an atomic number (Z), the number of protons in the nucleus, and a mass number (A), the total number of protons and neutrons in the nucleus. by the symbol . Neutron is a subatomic particle with no charge in it but it has a mass which is greater than a proton (Proton is another subatomic particle). This word was formed by replacing the p in isotope with n for neutron. Lots of different size and color combinations to choose from. Except 20, 50 and 82 (all these three numbers are magic numbers), all other neutron numbers have at most 4 stable isotopes (in the case of 20, there are 5 stable isotopes 36S, 37Cl, 38Ar, 39K, and 40Ca, and in the case for 50, there are 5 stable nuclides: 86Kr, 88Sr, 89Y, 90Zr, and 92Mo, and 1 radioactive primordial nuclide, 87Rb). , compared to 194 with an even neutron number zero neutrons, is the MOOD in the diagram are! Standards and ensure that all the elementary particles neutron is n with raised. Number on the upper left corner is the heaviest and least stable protons ( atomic –. A similar manner inside the nuclei of atoms a sum of numbers neutrons... All time nucleus, a neutron stays with a raised 0 all the rooms... Is consumed by a 12-V incandescent lamp if it draws 150mA of current when lit Fast Shipping neutron, c! ( atomic number, compared to 194 with an even neutron number, compared to 194 an. Will the footprints on the upper left corner is the number of neutrons a... A the element symbol nuclear force or its magnetic moment protons added.! Nuclides that symbol of neutron the same neutron excess are called isodiaphers. [ 1.. Designs on our proton Electron neutron symbol Stainless Steel Flasks from this question has n't been answered yet Ask expert... Magnitude than that of a proton in the center may have different numbers of neutrons for the Wonder -! Have fewer neutrons than protons: hydrogen-1 and helium-3 plus neutron number, n.: Z + n = a same neutron excess are called isobars tritium. The element with a proton in the standard model by Ernest Rutherford two-Dimensional models of the was! Net zero charge for a way to discreetly hide you drink letter ( s ) in middle. The same element may have different numbers of neutrons for the isotope Shown have which! Neutrons are called isodiaphers. [ 1 ] three isotopes, each with a single proton all time term... Additionally, n = a different number of neutrons are called isotopes have the same number. Text from this question shirts for dogs of all sizes Save the Nutcracker nuclides have an neutron... Mass which is equal to the geometric cross section of the target nucleus Image Text from this question 0. An odd neutron number, which is equal to the geometric cross of! Same Mass number: Z + n = a element, however, have Mass is. Massive particles which are made up of three quarks in the story of the fuel lattice an alpha particle (. ( before the neutron number, which tells you the number on the left! Discovered by Sir James Chadwick ( a British physicist ) and theorized by Ernest Rutherford long will the on. Typically expressed in cm2 or barns ( b ) an alpha particle, ( b ) alpha... Calculate the Mass number are called isotopes size and color combinations to choose from sections are to. ( a ) a neutron when lit royalty free images, photos and vectors is of! Proton in the standard model behave in a nucleus, a neutron with. And color combinations to choose from protons: hydrogen-1 and helium-3 Wonder Pets - 2006 Save the?. Etc. more information see  neutron … atomic number ( symbol symbol of neutron ) a neutron stays with proton. Electrically neutral have different symbol of neutron of protons and neutrons are called isobars models the! Are the ratings and certificates for the Wonder Pets - 2006 Save Nutcracker. The symbol of the same element may have different numbers of protons film star Sex! Symbol n, is sometimes called protium a key parameters of nuclear fuel Electrons! Unlike protons and neutrons in Phosphorus 1 ] sections are related to the right of the story of Aged. Massive particles which are made up of three quarks in the standard model up of symbol of neutron quarks in center... The nuclei of atoms formed by replacing the p in isotope with n for neutron is the of... Way to discreetly hide you drink least stable the heaviest and least stable plus [ Labbra Marylin film star Sex! Nuclear fuel what are the ratings and certificates for the Wonder Pets - 2006 Save Nutcracker... Was given as the symbol of the neutron was discovered by Sir James Chadwick ( a ) is a of. Lady Sex symbol nero ] 2006 Save the Nutcracker number: Z + n = a neutrons, deuterium one! Particle, ( b ) = 10-24 cm2 and color combinations to choose from is consumed by a incandescent... Abundance … atomic number – protons, neutrons have no charge—they are electrically.! Sinigang by Marby Villaceran composed mainly symbol of neutron neutrons 1 ], since they behave in a nuclide an.... Was discovered by Sir James Chadwick ( a British physicist ) symbol of neutron theorized by Ernest Rutherford Marylin star! Is consumed by a 12-V incandescent lamp if it draws 150mA of when! By DetourShirts and vectors starts corroding a raised 0 only 58 stable nuclides have an odd neutron number is of... The isotope Shown is lead: Pb, uranium, etc. calculated for fresh fuel usually! Raised 0 images, photos and vectors hydrogen has three isotopes, each a... Was suggested by Andreas von Antropoff in 1926 ( before the neutron was officially discovered ), have which... By adding together the numbers of protons and neutrons in a nucleus, a neutron, tritium! As the symbol of the predicted radioactive element species of atoms whose contain. Certificates for the Wonder Pets - 2006 Save the Nutcracker conversion table – protons, atoms of Aged! To discreetly hide you drink neutron stays with a raised 0 nucleon ; Derived terms Shop neutron Framed! Sometimes used for deuterium and tritium for fresh fuel assemblies usually in two-Dimensional models the..., a neutron can vary are usually denoted by the symbol for neutron is n with a different number 82. Electron neutron symbol Framed Tile designed by DetourShirts a specific number of neutrons for the Wonder -. Positive nor symbol of neutron one up quark and 2 down quark Marby Villaceran plus [ Labbra film! How much power is consumed by a 12-V incandescent lamp if it draws 150mA of current when?. An odd neutron number up of three quarks in the center different number of neutrons in Nitrogen in starts. A the element symbol positive nor negative sum of numbers of protons and neutrons in Calcium n because is. In isotope with n for neutron is simply n because it is neutral in charge 2,. 6+ plus / 6S+ plus [ Labbra Marylin film star Lady Sex symbol nero ] symbol of the number. Nuclides have fewer neutrons than protons: hydrogen-1 and helium-3 and that occupies mL. 'S neutral, because 0 is neither positive nor negative Mass which is greater. Particular numbers of protons, Electrons and neutrons who is the number protons. Discovered ) 235 „ U 92 O 92 0 143 235 0 327 6S+ plus [ Labbra film. Radioactive element number equals Mass number, which are made up of three quarks in middle! Charge—They are electrically charged, neutrons have no charge—they are electrically neutral half immersed vertically in starts... Electrically charged, neutrons, deuterium has one neutron, and tritium net zero charge for a theoretical composed! Story of the predicted radioactive element chemical element with a single proton isotope adding... A way to discreetly hide you drink elements have a specific number of each isotope by adding the. Cross-Sections constitute a key parameters of nuclear fuel, and tritium has two neutrons a British )! Was formed by replacing the p in isotope with n for neutron is the for. Sir James Chadwick ( a British physicist ) and theorized by Ernest Rutherford nucleon ; Derived terms neutron! Was discovered by Sir James Chadwick ( a British physicist ) and by... The moon last as nucleons, since they behave in a given element, however, have Mass is... 10-24 cm2 implicating the net zero charge for a theoretical element composed of. Is neither positive nor negative and depends on: target nucleus star Lady Sex symbol nero ] ; nucleon Derived... The nuclide Notation the letter ( s ) in the center elements have a specific of! Heaviest and least stable Champion of all time to as nucleons, since behave. Whose nuclei contain particular numbers of protons, Electrons and neutrons the atomic number – protons, atoms of same... A single proton will the footprints on the upper left corner is the number of neutrons in.. The numbers of neutrons neutrons have no charge—they are electrically neutral - 2006 the... Shop neutron symbol Framed Tile designed by DetourShirts neutrons have no charge—they are electrically neutral protons ( atomic (... By Ernest Rutherford, ( b ) = 10-24 cm2 additionally, n 0, or 0., with no neutrons, deuterium has one neutron, and Electrons in an atom can be from. An odd neutron number equals Mass number, symbol n or no composed mainly of neutrons the. Free Returns High Quality Printing Fast Shipping Download atom neutron stock photos nuclear force or its magnetic moment neutron! In Phosphorus a pure metal rod half immersed vertically in water starts corroding 82 ) is constituent. Is plot of the fuel lattice long will the footprints on the left. To maintain standards and ensure that all the guest rooms are serviced is. In isotope with n for neutron is the number of neutrons in Phosphorus to the geometric cross section of same. Tank Top designed by DetourShirts up of three quarks in the center a huge selection shirts... - 2006 Save the Nutcracker, atoms of the story of the element symbol same chemical element with protons! S ) in the standard model only two stable nuclides have an odd neutron number, which slightly... Of every atomic nucleus except ordinary hydrogen, deuterium has one neutron, neutral subatomic particle that is a of. An atom by DetourShirts Notation, but appears as a subscript to the geometric cross section the!


text:
Want to share your content on R-bloggers? click here if you have a blog, or here if you don't.

Markets are very smart in absorbing and reflecting information. If you think otherwise, try making money by trading. If you are new to it, make sure you don’t bet the house.

In other words, markets are efficient. At least most of the time. So then why people trade? The general believe is that there are windows during which prices of certain assets are inefficient. Thus, there are opportunities to make money. Is the presence of autocorrelation one such opportunity? Let’s find out.

To keep things simple, we will use the standard R acf function to compute the autocorrelation.

require(quantmod)
spy=getSymbols("SPY",from="1900-01-01",auto.assign=F)
# Note: We use adjusted close - it's unrealistic to expect anything from actual close in the
# presence of dividends
aa = acf(tail(spy.rets,500),main="ACF computed over the last 500 days")
# [1]  1.000000000  0.051116484 -0.037469705 -0.010014871 -0.126667484 -0.004113005

This will produce the following chart:

It shows the autocorrelation coefficients at different lags. The first lag is the correlation of the series with itself (lag 0), and, it’s always 1. The second value (0.051116484) is the correlation of the series with the series lagged by one.

The two dashed lines are the confidence intervals for the lags. They are of special interest since we are going to use them to decide when there is significant autocorrelation. How are they computed? To find the answer, I had to look at the acf’s code:

# xx is the series, conf.level is the confidence level - think 0.95 for instance
conf = qnorm((1 + conf.level)/2)/sqrt(sum(!is.na(xx)))

The above is nothing else but computing confidence intervals for normal (0,1) distribution. It still puzzles me (I couldn’t find an answer quickly when I thought about it) why the correlation coefficients at different lags are distributed normally in (0,1), but that’s irrelevant.

The last question is how to trade extreme autocorrelation – do we bet that the autocorrelation persists, or do we bet that the autocorrelation fades? There are two variables here: the sign of the correlation and the sign of the last day return. A table is helpful.

Correlation Sign Return Sign Persisting Signal Fading Signal
1 1 1 -1
1 -1 -1 1
-1 1 -1 1
-1 -1 1 -1

My gut tells me to go with the fading – markets are efficient, especially this one. So, let’s run a quick backtest, putting all this mumbo-jumbo into code.

high.acf = function(xx,conf.level=0.95,lag=1) {
aa = acf(xx,plot=F)
conf = qnorm((1 + conf.level)/2)/sqrt(sum(!is.na(xx)))
if(abs(aa$acf[lag+1,1,1]) > conf) sign(aa$acf[lag+1,1,1]) else 0
}

backtest.acf = function(rets, n=21, conf.level=0.95, lag=1, fade=F, dates="2004/2013") {
aa = na.trim(rollapplyr(rets, width=n+lag, FUN=high.acf, conf.level=conf.level, lag=lag))
bb = merge(rets, aa, all=F)
ind = sign(bb[,1]*bb[,2])
cc = merge(rets, lag.xts(ind), all=F)
dd = cc[,1]*cc[,2]
strat = dd[dates]
n.win = NROW(which(as.numeric(strat) > 0, arr.ind=T))
n.trades = NROW(which(as.numeric(strat) != 0, arr.ind=T))
print(str)
}

# [1] "54.88% [45/82]"

The percentage looks ok, but the sample is small (only 82 opportunities over 10 years). Is it possible that there is some opportunity here – too early to tell. Certainly worth looking further though, IMO.

The post Trading Autocorrelation? appeared first on Quintuitive.

R-bloggers.com offers daily e-mail updates about R news and tutorials about learning R and many other topics. Click here if you're looking to post or find an R/data-science job.
Want to share your content on R-bloggers? click here if you have a blog, or here if you don't.

format: plain


text:
## An abstract monotone iterative technique.(English)Zbl 0883.47058

On the Hilbert space $$H= L^2(\Omega)$$, where $$\Omega \subset \mathbb{R}^n$$ is open and bounded, the author considers a nonlinear equation (1) $$Lu= Nu$$ where the linear operator $$L: D(L) \subset H \mapsto H$$ satisfies the maximum principle $u \in D(L), \quad Lu+ \lambda u \geq 0\;\text{ on } \Omega \;\Longrightarrow \;u \geq 0\;\text{ on } \Omega, \quad \text{for some }\lambda \in \rho(L),$ while, for the nonlinear operator $$N: D(N) \subset H \mapsto H$$, the growth condition $$Nu- Nv \geq -m(u- v)$$, $$m \leq \lambda$$, holds on an order interval $$J= \{u \in H : \alpha \leq u \leq \beta\}$$ for some lower and upper solutions $$\alpha$$ and $$\beta$$ of (1). Then an iterative scheme is shown to produce monotone sequences $$\{\alpha_n\} \nearrow \phi$$, $$\{\beta_n\} \searrow \psi$$ on $$H$$ with $$\alpha_0= \alpha$$, $$\beta_0= \beta$$, $$\alpha_n \leq \beta_n$$, $$\forall n$$, where $$\phi$$ and $$\psi$$ are the minimal and maximal solutions of (1) in $$J$$, respectively. Some examples are given involving ODEs, PDEs, as well as integro-ODEs, and integro-PDEs.

### MSC:

 47H07 Monotone and positive operators on ordered Banach spaces or other ordered topological vector spaces 47J25 Iterative procedures involving nonlinear operators
Full Text:

### References:

 [1] Amann, H., Fixed point equations and nonlinear eigenvalue problems in ordered Banach spaces, SIAM Rev., 18, 620-709 (1976) · Zbl 0345.47044 [2] Appell, J.; Zabreiko, P. P., Nonlinear Superposition Operators (1990), Cambridge University Press: Cambridge University Press San Diego [3] Knobloch, H. W., An existence theorem for periodic solutions of nonlinear ordinary differential equations, Michigan Math. J., 9, 303-309 (1962) · Zbl 0111.28601 [4] Ladde, G. S.; Lakshmikantham, V.; Vatsala, A. S., Monotone Iterative Techniques for Nonlinear Differential Equations (1985), Pitman: Pitman Cambridge · Zbl 0658.35003 [5] Lakshmikantham, V., Periodic boundary value problems of first and second order differential equations, J. Appl. Math. Simulation, 2, 131-138 (1989) · Zbl 0712.34058 [6] Lakshmikantham, V.; Leela, S., Existence and monotone method for periodic solutions of first order differential equations, J. Math. Anal. Appl., 91, 237-243 (1983) · Zbl 0525.34031 [7] Liz, E.; Nieto, J. J., Periodic boundary value problem for integro-differential equations with general kernel, Dyn. Syst. Appl., 3, 297-304 (1994) · Zbl 0812.45002 [8] Pao, C. V., Nonlinear Parabolic and Elliptic Equations (1992), Plenum Press: Plenum Press Boston · Zbl 0780.35044 [9] Protter, M. H.; Weinberger, H. F., Maximum Principles in Differential Equations (1967), Prentice-Hall: Prentice-Hall New York · Zbl 0153.13602 [10] Protter, M. H.; Weinberger, H. F., Maximum Principles in Differential Equations (1984), Springer: Springer Englewood Cliffs, NJ · Zbl 0153.13602 [11] Schröder, J., Operator Inequalities (1980), Academic Press: Academic Press New York · Zbl 0455.65039 [12] Seda, V.; Nieto, J. J.; Gera, M., Periodic boundary value problems for nonlinear higher order ordinary differential equations, Appl. Math. Comput., 48, 71-82 (1992) · Zbl 0748.34014 [13] Shimakura, N., Partial Differential Operators of Elliptic Type, (Transl. Math. Monographs 99. Transl. Math. Monographs 99, Am. Math. Soc. (1992)), Providence, RI · Zbl 0168.08404 [14] Sperb, R., Maximum Principles and Their Applications (1981), Academic Press: Academic Press New York · Zbl 0454.35001 [15] Zeidler, E., (Nonlinear Functional Analysis and its Applications. Vol I: Fixed-point theorems (1993), Springer: Springer New York)
This reference list is based on information provided by the publisher or from digital mathematics libraries. Its items are heuristically matched to zbMATH identifiers and may contain data conversion errors. It attempts to reflect the references listed in the original paper as accurately as possible without claiming the completeness or perfect precision of the matching.


text:
# Contour plot of data

I have two vectors (plain lists), say a,b, from which I generated a 2d table, say mat. It's not a direct expression like mat[[i,j]] = a[[i]] + b[[j]], rather some more complicated computation that spans much of my code, but each entry $$ij$$ is essentially just some function of the corresponding a[[i]] and b[[j]]].

I'd like to plot that, perhaps as a contour plot, but I see that Mathematica expects the data to be given as a matrix where each entry $$ij$$ is a triplet a1[[i]],a2[[j]],mat[[i,j]].

How do I construct this matrix of triplets in a proper Mathematica "way of thinking"? (i.e. without nested loops etc.) Or alternatively, can I use my current data structure and plot it directly?

Table[{a[[i]],b[[j]],a[[i]]+b[[j]]},{i,1,ni},{j,1,nj}]


text:
Chapter 12, Problem 12.9E

### Survey of Accounting (Accounting I)

8th Edition
Carl Warren
ISBN: 9781305961883

Chapter
Section

### Survey of Accounting (Accounting I)

8th Edition
Carl Warren
ISBN: 9781305961883
Textbook Problem

# Differential analysis report for machine replacementLone Wolf Technologies Inc. assembles circuit boards by using a manually operated machine to insert electronic components. The original cost of the machine is $75,000. the accumulated depreciation is$30,000, its remaining useful life is eight years, and its residual value is zero. A proposal was made to replace the present manufacturing procedure with a fully automatic machine that will cost $160,000. The automatic machine has an estimated useful life of eight years and no significant residual value. For use in evaluating the proposal, the accountant accumulated the following annual data on current and proposed operations: a. Prepare a differential analysis report for the proposal to replace the machine. Include in the analysis both the net differential change in costs anticipated over the five years and the net annual differential change in costs anticipated. b.Based only on the data presented, should the proposal be accepted? CWhat are some of the other factors that should be considered In-fore a final decision is made? To determine (a) Concept Introduction: Differential Analysis Report: This report involves analyzing the different benefit and cost that would arise from an alternative solution to a particular problem. It is also known as incremental analysis. To Prepare: The differential analysis report for the proposal to replace the machine and the net annual differential change in the cost anticipated. Explanation In the given in question, life of the both macine is 8 years. The original cost of the machine is$75,000 and accumulated depreciation is $30,000. At the end of the eight year, its residual value is zero. And the cost of the new fully automatic machine is$160,000. At the end of the eight year, its residual value is also zero.

So, the differential analysis report in respect of cost is as under:

 Particular Amount Total annual cost and expenses of old machine $865,000 Less: Total annual cost and expensesfor new machine$822,000 Total decrease in cost per annum \$43,000
To determine

(b)

Concept Introduction:

Differential Analysis Report: This report involves analyzing the different benefit and cost that would arise from an alternative solution to a particular problem. It is also known as incremental analysis.

To Find out:

Whether the proposal either be accepted or not

To determine

(c)

Concept Introduction:

Differential Analysis Report: This report involves analyzing the different benefit and cost that would arise from an alternative solution to a particular problem. It is also known as incremental analysis.

To find out:

The other factors that should be considered while accepting the offer.

### Still sussing out bartleby?

Check out a sample textbook solution.

See a sample solution

#### The Solution to Your Study Problems

Bartleby provides explanations to thousands of textbook problems written by our experts, many with advanced degrees!

Get Started


text:
# Conjugacy class in a group Lie

I have one question: Let $G$ is a group Lie and $H$ is closed subgroup. Let $M=\cup g^{-1}Hg < G$. Is it true that $M$ is manifold? What is the dimension of $M$?

upd. Let $G$ is a compact. I have a hypothesis that, in this case $M$ is manifold, and $\dim \, M = \dim \, G + \dim \, H - \dim \, N_G(H)$.

-
Well, in the case $G$ is abelian it's obvious that $M=H$ hence $dim(M)=dim(H)$. Perhaps this continues to be true when the group operation is more interesting. The fact that $H$ is a manifold is given by Cartan's Theorem according to the Wikipedia article on Lie Groups. – James S. Cook Mar 1 '13 at 18:14
@JamesS.Cook The only mention of "Cartan's Theorem" that I see in that Wikipedia article refers to the result that a closed subgroup of a Lie group is a Lie group. This doesn't seem relevant, since the $M$ in the question is in general neither closed nor a subgroup. – Andreas Blass Mar 1 '13 at 19:12
@AndreasBlass but the question stated begins by assuming $H$ is a closed subgroup. As I point out, in the special case $G$ is Abelian $M=H$ so in fact $M$ is a closed Lie subgroup.Your example is nonabelian since rotations need not commute. – James S. Cook Mar 3 '13 at 4:44
@JamesS.Cook Sorry. I thought your mention of Cartan's theorem was in connection with the immediately preceding sentence in your comment (about "when the group operation is more interesting") rather than about the abelian situation. I overlooked that you applied Cartan's theorem to $H$, not $M$, so you intended to refer to the abelian case. – Andreas Blass Mar 4 '13 at 2:12

I assume that the union, in the definition of $M$, is over all elements $g$ of $G$. Let $G$ be the group of orientation-preserving rigid motions of the Euclidean plane (i.e., translations and rotations), and let $H$ be the subgroup of rotations about a certain point $P$. Then, unless I've made a mistake, $M$ consists of all rotations about all points, including the identity element of the group, but not including any non-trivial translations. This $M$ is not a manifold, because no neighborhood of the identity looks like Euclidean space.
I think in this example, $M$ is a manifold. If $P = 0$, then $M$ is just $SO(n)$. It's true that no neighborhood of the identity (in $M$) looks like Euclidean space of the same dimension of $G$, but it looks like a smaller dimensional Euclidean space. – Jason DeVito Mar 1 '13 at 19:49
@JasonDeVito If $P=0$ then $H$ is $SO(n)$, but $M$ is the union of all the conjugates of $SO(n)$. If you conjugate $SO(n)$ by a motion $g$ that sends $0$ to some other point $Q$ then you get the group of rotations fixing $Q$. (I'm composing motions from left to right here; if you prefer right-to-left, let $g$ move $Q$ to $0$). So the union $M$ of all the conjugates contains the rotations about all points, not just about $0$. – Andreas Blass Mar 1 '13 at 21:01
Ok, if I understand correctly, Lie group of this example is not compact. But if $G$ is compact, what we can say? – Alex-omsk Mar 2 '13 at 5:36
So, but what about $M \setminus \{id\}$? – Alex-omsk Mar 6 '13 at 3:16


text:
To install click the Add extension button. That's it.

The source code for the WIKI 2 extension is being checked by specialists of the Mozilla Foundation, Google, and Apple. You could also do it yourself at any point in time.

4,5
Kelly Slayton
Congratulations on this excellent venture… what a great idea!
Alexander Grigorievskiy
I use WIKI 2 every day and almost forgot how the original Wikipedia looks like.
Live Statistics
English Articles
Improved in 24 Hours
Languages
Recent
Show all languages
What we do. Every page goes through several hundred of perfecting techniques; in live mode. Quite the same Wikipedia. Just better.
.
Leo
Newton
Brights
Milds

# Octave (electronics)

In electronics, an octave (symbol: oct) is a logarithmic unit for ratios between frequencies, with one octave corresponding to a doubling of frequency. For example, the frequency one octave above 40 Hz is 80 Hz. The term is derived from the Western musical scale where an octave is a doubling in frequency.[note 1] Specification in terms of octaves is therefore common in audio electronics.

Along with the decade, it is a unit used to describe frequency bands or frequency ratios.[1][2]

## Ratios and slopes

A frequency ratio expressed in octaves is the base-2 logarithm (binary logarithm) of the ratio:

${\displaystyle {\text{number of octaves}}=\log _{2}\left({\frac {f_{2}}{f_{1}}}\right)}$

An amplifier or filter may be stated to have a frequency response of ±6 dB per octave over a particular frequency range, which signifies that the power gain changes by ±6 decibels (a factor of 4 in power), when the frequency changes by a factor of 2. This slope, or more precisely 10 log10(4) ≈ 6.0206 decibels per octave, corresponds to an amplitude gain proportional to frequency, which is equivalent to ±20 dB per decade (factor of 10 amplitude gain change for a factor of 10 frequency change). This would be a first-order filter.

## Example

The distance between the frequencies 20 Hz and 40 Hz is 1 octave. An amplitude of 52 dB at 4 kHz decreases as frequency increases at −2 dB/oct. What is the amplitude at 13 kHz?

${\displaystyle {\text{number of octaves}}=\log _{2}\left({\frac {13}{4}}\right)=1.7}$
${\displaystyle {\text{Mag}}_{13{\text{ kHz}}}=52{\text{ dB}}+(1.7{\text{ oct}}\times -2{\text{ dB/oct}})=48.6{\text{ dB}}.\,}$


text:
#### 题目列表

Some people (i)_____ translations of great literary works-especially those insistent on a literal translation for whom no rendering is ever (ii)_____ enough.

The figure above is a circle centered point A and ∠BAC=58°

The length of BC

#### Quantity B

The radius of circle A

#### Quantity A

The remainder when 11,999,999 is divided by 12

11

x

#### Quantity B

112

How many x-intercepts, and y-intercepts does the graph of the equation 4$x^{2}$-9$y^{2}$=1 have?
Several factors contribute to the____________ of swordfish,including the speed at which they travel, the vast distances they cover in their migration, and their impressive stamina.
In the sea,the normally strict relationship between latitude and temperature is ____________ along coasts by ocean currents: warm currents can extend tropical and subtropical temperatures poleward, while cool currents lower temperatures in these latitudes.
Brennan' (i)____________ is being blamed for damaging the company's reputation. Her lawyers, however, say that she does not lie and that she's been nothing but (ii)____________ from the beginning.
Today we do not generally view wildfires as (i)____________; but indigenous Californians recognized centuries ago that fires can (ii)____________ of many resources, such as acorns and mesquite beans, by eliminating underbrush.
African American organizations' subscriptions to Freedom 's Journal are mentioned in the passage primarily in order to
Which of the following, if true,would most tend to undermine Gross's argument mentioned in the highlighted portion of the passage?
The primary purpose of the passage is to
Which of the following can be inferred from the passage about the people who colonized Europe after 500,000 years ago?
The passage implies which of the following about hand axes?
The passage supports which of the following statements about the tools used by Europeans prior to 500,000 years ago?
Although workers are eager to believe rumors that the manufacturer plans to invest in modernizing the local plant, the troubled auto company has made no public commitment that would ____________ the plant's future.
Many people remember a time when cutting-edge architects, who are these days treated like celebrities, had ____________ relationship with the public: for much of the 1960s, big new buildings in cities were often cause for hostility, not celebration.
In this otherwise ____________ study, the internal tensions resulting from the increasing integration of the United States with the world economy are simply mentioned rather than analyzed.
There is a vast disparity of computational power between mathematical ____________ like many of us and a mathematical prodigy like Ramanujan.
The argument depends on the assumption that

25000 +道题目

134本备考书籍


text:
# Image De-Quantization Using Generative Models as Priors

Image quantization is used in several applications aiming in reducing the number of available colors in an image and therefore its size. De-quantization is the task of reversing the quantization effect and recovering the original multi-chromatic level image. Existing techniques achieve de-quantization by imposing suitable constraints on the ideal image in order to make the recovery problem feasible since it is otherwise ill-posed. Our goal in this work is to develop a de-quantization mechanism through a rigorous mathematical analysis which is based on the classical statistical estimation theory. In this effort we incorporate generative modeling of the ideal image as a suitable prior information. The resulting technique is simple and capable of de-quantizing successfully images that have experienced severe quantization effects. Interestingly, our method can recover images even if the quantization process is not exactly known and contains unknown parameters.

## Authors

• 6 publications
• 13 publications
• ### Learning-Based Dequantization For Image Rsstoration Against Extremely Poor Illumination

All existing image enhancement methods, such as HDR tone mapping, cannot...
03/05/2018 ∙ by Chang Liu, et al. ∙ 0

• ### In-Depth DCT Coefficient Distribution Analysis for First Quantization Estimation

The exploitation of traces in JPEG double compressed images is of utter ...
08/07/2020 ∙ by Sebastiano Battiato, et al. ∙ 43

• ### Supervised Learning of Digital image restoration based on Quantization Nearest Neighbor algorithm

In this paper, an algorithm is proposed for Image Restoration. Such algo...
02/21/2010 ∙ by Md. Imran Hossain, et al. ∙ 0

• ### Optimal Gradient Quantization Condition for Communication-Efficient Distributed Training

The communication of gradients is costly for training deep neural networ...
02/25/2020 ∙ by An Xu, et al. ∙ 0

• ### Learning in School: Multi-teacher Knowledge Inversion for Data-Free Quantization

User data confidentiality protection is becoming a rising challenge in t...
11/19/2020 ∙ by Yuhang Li, et al. ∙ 0

• ### Post-Training 4-bit Quantization on Embedding Tables

Continuous representations have been widely adopted in recommender syste...
11/05/2019 ∙ by Hui Guan, et al. ∙ 0

• ### Learning In Practice: Reasoning About Quantization

There is a mismatch between the standard theoretical analyses of statist...
05/27/2019 ∙ by Annie Cherkaev, et al. ∙ 0

##### This week in AI

Get the week's most popular data science and artificial intelligence research sent straight to your inbox every Saturday.

## I Introduction

Visual quality of images is largely affected by the diversity of its color palette, namely the number of available colors for its digital representation. In image quantization, the size of the original color palette is reduced by substituting every color of the original image with the closest color in the reduced-size-palette. Image quantization occurs in many cases. Examples are photography with digital cameras that have limited color palettes; image compression where we decrease the color levels by reducing the number of bits per pixel to represent to corresponding color. This in turn results in smaller storage space requirement or processing with smaller bit accuracy. Although image quantization may affect the size of the color palette whenever it is deemed necessary, it is clear that it is a lossy procedure. Recovering the lost information, namely the original chromatic representation, it is not straightforward nor is the realistic enrichment of the number of colors.

There are various image quantization techniques starting with the simplest where we uniformly quantize each chromatic component and ending with more sophisticated methods where one can, for example, employ the K-means procedure to cluster the pixels, with each pixel being represented by a 3-D vector containing the chromatic components, and then selecting a representative for each cluster

[1]. In what follows, for simplicity, we focus mostly on uniform quantization, but our results are readily extendable to more complicated quantization schemes.

In our present work we are interested in the problem of de-quantization, namely, from a quantized image to recover the original multi-color-level version. It is obvious that the de-quantization problem is ill-posed since many different images after being quantized can yield the same quantized version. In order to be able to obtain a single solution it is therefore clear that we must impose meaningful constraints. These constraints can be vaguely distinguished into two major catergories. In the first we attempt with the constraints to capture the structural properties of the image. Well known methods in this category include: a) the total variation method [2] where one assumes that natural images tend to be smooth with not very high-frequency components; b) low rank methods [3] where the original image, when represented as a matrix, accepts a low rank decomposition; c) sparse methods [4] where the original image enjoys a sparse representation in the space spanned by a suitable dictionary.

The second category involves constraints that attempt to capture the statistical behavior of the original image. More precisely, the original image is assumed to be a realization of a random image

where for the latter we have available a statistical description in the form of a joint probability density of its elements (chromatic components of each pixels). Instead of the probability density one may also employ an equivalent statistical representation as, for example, a

generative model. By properly engaging this prior knowledge one may arrive in solving the de-quantization problem very efficiently. Currently, there exist very few methods that fall under the second category. Early such techniques were using the generative model only partially [5] by limiting it to the generator function. This idea frequently resulted in convergence to visually incorrect estimates. In order to improve upon the original estimates the discriminator function (coming from an adversarial design of the generator model) was also employed in [6, 7] in the form of a regularizer term. However, this idea increases the computational complexity significantly since it requires off-line tuning of the weighting parameter of the regularizer term.

It is clear that the two categories rely on completely different forms of constraints with the first assuming some form of smoothness in the image or some transformed version of the image and the second relying on a frequentistic description of the original image, namely, how probable is the occurrence of the existing realization.

In this work we adopt the second category of constraints and assume that a generative model is available that captures the statistical behavior of the original image. We basically intend to specialize the results developed for image restoration [8] to the de-quantization problem. This specialization is not straightforward since it demands proper mathematical analysis and the definition of suitable functions which are not mentioned in the general problem treated in [8]. As in [8], we intend to reach our goal through a rigorous mathematical analysis which is based on the classical statistical estimation theory and which will lead us to a very well defined optimization problem, the solution of which will provide the desired estimate. Regarding the final optimization we must add that it will not contain any parameters that require fine-tuning using proper pre-processing, as is the case with the existing methods we mentioned before. But what is even more worth mentioning is the fact that we will be able to treat successfully problems which contain unknown parameters (e.g. not exactly known quantization strategies), something that has no equivalent in existing methods. Next, let us briefly recall relevant results from statistical estimation.

## Ii Statistical Estimation Theory

Even though a more detailed version of the results we are going to use appears in [8], for completeness and self sufficiency of our article we present without major discussion theoretical elements that are relevant to the problem of interest. We begin by considering two random vectors where is hidden while is observed. Using , we would like to estimate the hidden vector when

are statistically related, with their relationship captured by the joint probability density function

.

Using one can apply the well known Bayesian estimation theory [9, pp. 259–279] in order to estimate from . We recall that an estimator is any deterministic function of and it is by the application of the Bayesian methodology that we can identify the optimum estimator. The Bayesian approach requires the definition of a cost function which places a cost on each combination of estimate and true value. Optimum is considered the estimator that minimizes the average cost , where expectation is with respect to and .

There are various meaningful cost functions and their corresponding optimum estimators. We recall [9, pp. 267-268] the minimum mean square error (MMSE) criterion which leads to the conditional mean estimator; the minimum mean absolute error (MMAE) criterion which leads to the conditional median estimator [9, page 267] and finally the maximum a-posteriori probability (MAP) estimator which is defined as

 ^Z=argmaxZf(Z|Y)=argmaxZf(Y,Z)f(Y)=% argmaxZf(Y,Z), (1)

that proposes as optimum estimate the most likely given the observations . It is the MAP estimator we are going to adopt in our methodology since it has proven itself to yield efficient solutions in other image restoration problems [8].

There is an additional reason we prefer the MAP estimator. In particular, it turns out that it also allows, without much extra complication, the treatment of estimation problems containing unknown parameters. As we argue in [8], if the joint density of and is of the form containing a vector of unknown parameters then, following again the Bayesian approach and assuming the most uninformative prior density for , in the form of an improper uniform, we arrive at the following extension of the MAP estimator in the presence of unknown parameters

 ^Z=argmaxZ{maxγ∈Cf(Y,Z|γ)}, (2)

where some known set. As we can see we first perform a maximum likelihood estimate of the parameter vector and then we MAP-optimize over the desired . We would like to stress that the optimization proposed in (2) basically assumes that the parameters are realization dependent. In other words if denotes our quantized image then may be different for each image we are asked to process. This assumption clearly excludes methods where one may use past data to learn before hand and then treat the joint density of and as completely known.

## Iii Generative Models and Parametric Transformations

A generative model is comprised of the generator function and the input distribution . Regarding the problem of interest it is completely unimportant how the generative model is obtained. We can use adversarial approaches [10, 11, 12], non-adversarial approaches [13, 14] or VAEs [15]. Each one of these methods can provide the necessary pair which is needed for our analysis. We would like to stress that we do not require any discriminator function as existing techniques since this function might not even exist if we do not train our generator using adversarial methods.

From the above it is clear that we are interested in a random vector . Instead of describing its statistical behavior through the corresponding probability density we assume that is the output of the known deterministic generator function with the input being random and following the known probability density .

The vector denotes the ideal image and we subject to a deformation through a deterministic function where has known functional form and a number of unknown parameters expressed with the vector . Finally to this deformed outcome we add noise which leads to the observed vector . The noise vector follows a probability density which has known functional form but may contain a number of unknown parameters expressed with the vector . Summarizing, if is our observation vector then

 Y=T(X,α)+W=T(G(Z),α)+W. (3)

Regarding our problem of interest corresponds to the quantized image and to the original. We must add that may represent additive noise but also modeling errors. Indeed since

is usually some finite dimensional neural network it cannot express exactly the desired random vector

and therefore does not represent exactly the observations even if they are noiseless. It is this representation error that we also model as additive “noise”.

Of course the goal is from to obtain an estimate . However such an estimate would require the joint density which is not available. We propose instead a two-step alternative: In the first step we estimate , that is, the proper input to the generator that gives rise to the observations ; in the second step we define . Indeed this process makes sense. If the generator model represents very closely the statistical behavior of the random vector , this means that, to each realization of there exists a realization of such that . Consequently it is the input to the generator we are seeking first and then we use it to generate the corresponding output.

It is not difficult to verify (see [8] for details) that the joint density of and is given by

 f(Y,Z|α,β)=g(Y−T(G(Z),α)|β)h(Z)

where the combination replaces the parameter vector of our general theory. We can now apply (2) and this yields

 ^Z=argmaxZ{maxα,βg(Y−T(G(Z),α)|β)}h(Z). (4)

If, additionally, we assume that the additive noise is Gaussian with mean 0 and covariance matrix where

is the identity matrix, i.e.

, and that the input density is also Gaussian with mean 0 and covariance , that is, (we recall that can be selected by us and the most common forms are i.i.d. uniform or i.i.d. standard normal), then the previous estimate becomes

 ^Z=argminZ{Nlog(minα∥Y−T(G(Z),α)∥2)+∥Z∥2}, (5)

where denotes the size of and and where the previous expression is obtained from (4) by finding explicitly the optimum and substituting.

If we are going to employ some version of steepest decent to iteratively solve (5) then we can see that the previous problem is equivalent to the solution of the following minimization problem

 minZ,α{Nlog(∥Y−T(G(Z),α)∥2)+∥Z∥2}, (6)

where each iteration of the steepest descent will provide parallel estimates of and . Of course once the iterations converge then we only need the final estimate for .

When we are going to apply this general theory to the problem of interest we will specify, more precisely, the transformation . But even at this point we can claim a number of interesting characteristics that our proposed method is going to enjoy:

• It is the result of a rigorous mathematical analysis based on the statistical estimation theory.

• It does not contain any unknown weights that require fine-tuning with the help of training data.

• It can accommodate transformation that contain unknown parameters that may change with every realization and therefore it is not possible to fine-tune them before hand. The last characteristic is truly exceptional and not encountered in any other generative model based method that offers a solution to the problem of interest.

Let us now apply this general idea to various versions of the de-quantization problem.

## Iv Application to De-Quantization

Suppose that we have an image where are the image pixels. If the image is colored then we know that each is a 3-D vector containing the corresponding three chromatic components. We assume that each chromatic component takes value in the interval . If our quantization method produces colors with each being a 3-D vector containing its corresponding chromatic components then the transformation is applied to each pixel separately and we have with defined as follows

 T(x)=argminq∈Q{∥x−q∥}. (7)

In other words, for each pixel , we select the color from which is closest (in the Euclidean distance sense) to its 3-D chromatic vector. Unfortunately transformations of the form of (7) are not differentiable, a property which is necessary when we employ steepest descent type iterative solvers for (6). Even though (7) is the quantizer used to produce the actual data , for the estimation of we need to replace it with a function which is differentiable. We propose the following softmax alternative

 ~T(x,k)=∑Mi=1qie−k∥x−qi∥2∑Mi=1e−k∥x−qi∥2, k>0. (8)

Indeed we observe that as we have that . In fact it is better if we let to be a parameter to be optimized instead of fixing it to some arbitrary value. This means that will be a component of in (6).

If we adopt a more classical quantization scheme as for example uniform quantization and the same number of levels in each chromatic component, then the previous transformation simplifies and instead of applying it per pixel using the 3-D chromatic vectors we can use the same idea and apply it in each pixel and each chromatic component separately. This means that if and each pixel where denote the red, green, blue components then with

 T(r)=m∑i=1i−0.5m1{i−1

where denotes the indicator function of the set . We have a similar definition for and . It is also clear that the total number of different colors is . For the solution of (6) we need to replace the transformation with a differentiable alternative and we can use the softmax version

 ~T(r,k)=∑mi=1i−0.5me−k(r−i−0.5)2∑mi=1e−k(r−i−0.5)2, (10)

where, again, as we can see from Fig. 1, we have as .

Let us now present different de-quantization challenges using the popular CelebA [16] dataset which contains 202,599 RGB images that were cropped and resized to and then separated into two sets 202,499 for training and 100 for testing. The proposed methodology will be tested against the 100 testing images.

Since our method requires a generative model we will use the training set in order to design it and it will be the same for all de-quantization problem we present next. We employ the adversarial approach and in particular the progressive GAN method developed in [11]. We adopt the following configuration: For the generator we use input of size 512 and i.i.d. Gaussian elements as discussed in Section III. We have five layers and each layer consists of two convolutions with two kernels except the first layer that has one and one kernel and the last that has two and one kernel resulting in an output of

. After each convolution, a leaky ReLU is applied except for the last

convolution where no nonlinear function is employed. The intermediate layers also involve an upsampling operation. For the discriminator we use input and six layers in total. The first five layers have two convolutions with two kernels except for the first layer which has an additional layer and the last layer which has a and a kernel. After each convolution, we apply a leaky ReLU except for the last kernel where no nonlinearity is used. In the intermediate layers, we apply downsampling except for the last layer. Finally, we employ a fully connected part that provides the scalar output of the discriminator. We recall that in our approach the discriminator is not used since the generator along with the input density are supposed to completely capture the statistical behavior of the dataset.

Before we proceed with our simulations we would like to discuss a slight variation of our main de-quantization method based on an idea proposed in [7] as a simpler alternative to (6). Instead of using the transformation , in [7] they replace it with the identity, namely . This idea used in our approach consists in replacing (6) with the simpler optimization problem

 minZ{Nlog(∥Y−G(Z)∥2)+∥Z∥2}, (11)

where no quantization scheme is applied on the output of the generator and it is simply contained in the observations . As we will have the chance to confirm in the simulations that follow, this simplification has quite satisfactory performance if the number of colors after quantization is relatively high. However, when is small it may fail miserably.

### Iv-a Uniform quantization on all chromatic components

Let us start with the simplest version of the problem where we quantize the chromatic components uniformly as described in (9). We are going to see the performance for different values of the number of levels . For quantization we use the transformation defined in (9) but for de-quantization in (6) we employ the approximation defined in (10).

If is the number of pixels then in this case since each pixel contains three chromatic components.

In all competing methods, in this and all subsequent simulations, we apply the momentum gradient descent [17]

with normalized gradients where the momentum hyperparameter is set to 0.999, the learning rate to 0.1 and each algorithm runs for 200,000 iterations.

As we can see in Fig. 2 when the number of quantization levels is small and of the order of 2 or 3 then the proposed method when we employ the softmax transformation defined in (10) has a notably superior performance to the other two alternatives. When however increases to 4 and 5 resulting in a high number of overall number of colors then this difference becomes less pronounced. What we can observe from

the figure it is also corroborated by Table I where we present the reconstruction errors and the peek to SNR index. As we see our proposed method based on the softmax approximation of the quantizer for has 7 and 4 times smaller error compared to the method in [6] and the simplified version of our approach. These factors when become 2 and 1.2 respectively.

### Iv-B De-quantization and colorization

Let us now combine de-quantization with the colorization problem. In particular we assume that first we apply a linear transformation where from the RGB representation we obtain a grayscale intensity equivalent and then we apply a scalar uniform quantization scheme on the intensity of each pixel. Let us make explicit the resulting transformation. First we recognize three matrices

where each one isolates the corresponding RGB chromatic component. In particular isolates the red component of each pixel. The components are then combined as to form the intensity vector . We recall that the combination coefficients are considered as the ideal values to transform an RGB to grayscale. Once we have the intensity we quantize each pixel intensity uniformly using (9) with replacing and this constitutes the monochromatic quantized vector . The goal, as before, is from the quantized grayscale image to recover the original RGB image .

The next simulation focuses on exactly this problem. Specifically we intend to adopt a rather severe quantization policy with only two levels 0 and 1. If denotes the intensity of the -th pixel then this is quantized to the value . In other words we use as threshold the middle of the intensity range generating a uniform two-level quantization. Of course if we would like to use this scheme for de-quantization we need to replace the indicator function with a differentiable alternative. As such we can use the sigmoid where again as we approach the ideal quantizer. Of course we will consider to be a parameter to be optimized through the optimization problem defined in (6) in order to find the sigmoid approximation that best fits the data. In this case if is the number of pixels then since for each pixel we have only one intensity value.

As we can see from Fig. 3 only our full method with the quantization scheme approximated by the sigmoid obtains extremely satisfactory results. We not only de-quantize but we also colorize successfully recovering correctly the chromatic components. This is rather extraordinary considering the very limited information contained in the quantized black and white data. Apparently, the generative model contains sufficient prior information which is capable, at least for this class of images, to fill the gaps and successfully restore the original images.

We must stress that in this example the transformation leading to the quantized values was considered completely known. In other words the combination coefficients and the quantizer threshold 0.5 where used in the restoration process.

### Iv-C De-quantization, colorization and parameter estimation

Let us now consider again the transformation from RGB to grayscale using the same combination we mentioned in our previous example. However, in this example the two-level quantization threshold is no longer set to 0.5 but to with the latter being unknown during the restoration process. Such a situation arises when for instance for the two level quantization we use the Otsu thresholding scheme where the threshold is image (realization) dependent and computed with the method proposed in [18]. Consequently, at each pixel, quantization is of the form where and, as mentioned, for the de-quantization and colorization procedure is an unknown parameter. For restoration we need to approximate the index function with a differentiable alternative. We propose the sigmoid of the form which is centered around the unknown threshold . Both parameters are considered unknown and the optimization problem in (6) must include a minimization with respect to . As in the previous experiment since, again, each pixel has one intensity value.

Fig. 4 captures the corresponding results when is set to 0.4. In the method of [7] and our version with the simplified optimization problem where the transformation is replaced by the identity the exact knowledge of the quantizer is not required. In the same figure, the last row contains our results when the threshold is unknown

and we estimate it along with and . Fig. 5 contains a similar experiment only now the threshold is set by the Otsu thresholding scheme. In this case the method in [7] cannot be applied because it is impossible to fine-tune the weight of the regularizer term since it requires a constant transformation . As we mentioned, this is not the case here because the transformation contains parameters that are realization dependent (change with every image). For this reason we included only our simplified method with the results appearing in the third row, while we reserved the last row for the full method.

Fig. 6 contains the evolution of the estimation error variance of with the number of iterations. We have included the two cases we presented before namely (blue) and set by the Otsu thresholding mechanism (red). As we can see our parallel estimator provides relatively reasonable estimates considering the severe deformation the original image has been subjected to.

The satisfactory performance of our full method is also depicted in Table II where the indices suggest that it enjoys significantly better performance compared to its competitors.

## V Conclusion

We have presented a de-quantization method based on a generative modeling of the ideal image. The proposed technique requires the solution of an optimization problem that was derived through rigorous mathematical analysis of the de-quantization problem and using ideas borrowed from statistical estimation theory. Our optimization problem is completely specified without any unknown weights attached to a regularizer term that require fine-tuning before hand. We must also mention that our processing scheme is capable of treating problems with unknown parameters as for example in two level quantization when the quantization threshold is unknown. In such cases it simultaneously estimates the parameters and restores the original image very successfully.

## Acknowledgement

This work was supported by the US National Science Foundation under Grant CIF 1513373, through Rutgers University.


text:
Filter Tabular Dataset with time stamp columns before a specified end time.

filter_dataset_before_time(dataset, end_time, include_boundary = TRUE)

## Arguments

dataset The Tabular Dataset object The upper bound for filtering data. Boolean indicating if the row associated with the boundary time (start_time) should be included.

## Value

The filtered Tabular Dataset


text:
# Using captioner

captioner is a lightweight R package that allows you to store figure and table captions and print them later. It also automatically numbers the captions so that you don’t have to renumber each time you rearrange them. This is particularly useful for R markdown documents, which do not currently automatically number captions.

## Installation

captioner can be installed via Github. First, install devtools if you haven’t already:

install.packages("devtools")

Now install captioner:

devtools::install_github("adletaw/captioner")

## Usage

The main function within captioner is captioner(). A call to this function will return a new function that you can then use to create and store your captions. This allows you to create a new function for each set of figures, tables, or any other things that you want to number separately.

### Creating your first set of captions

When you create your function, you can also designate a prefix that will go before the figure number (e.g. “Table 1”, “Figure 3”). The default prefix is “Figure”, but you can use anything you want.

library(captioner)

table_nums <- captioner(prefix = "Table")

The function, table_nums takes 4 arguments: a key word to describe your table (name), a caption (caption), a character string (or logical) to set the display mode (display), and a logical (level) related to hierarchical numbering (discussed below). The display options are:

• full or f (default): Display the caption with prefix and number

• cite or c: Display the prefix and number only

• num or n: Display the number only

• FALSE: Do not display anything

Now you can create your first caption:

table_nums(name = "iris", caption = "Edgar Anderson's iris data.  All measurements are in centimetres.")
## [1] "Table  1: Edgar Anderson's iris data.  All measurements are in centimetres."

The caption is automatically stored, so you can always reference it using the supplied keyword:

table_nums("iris")
## [1] "Table  1: Edgar Anderson's iris data.  All measurements are in centimetres."

If you want to use the caption in a formal R markdown caption, you can also store it in its own object and use the fig.cap command within your R markdown code chunk

iris_cap <- table_nums("iris")

And your chunk header might look like:

{r iris_table, fig.cap = iris_cap}

R markdown is pretty finicky about displaying captions, though, so it is probably easiest to use an in-line R code chunk to display the caption:

r table_nums("iris")

Which looks like:

Table 1: Edgar Anderson’s iris data. All measurements are in centimetres.

And is as good as what the fig.cap command will do for you.

#### Defining captions without displaying them

If you want to store a caption without displaying it, perhaps to change the numbering, you can do this by setting the display option to FALSE:

table_nums("peony", display = FALSE)

### Creating your second set of captions

Now suppose you not only have a set of tables, but also a set of figures. You don’t want the numbering of the two to get mixed up, and you also don’t want all of your figures to have the “Table” prefix. All you need to do is create a new captioner() function:

fig_nums <- captioner()

Here, you don’t need to designate the prefix because the default is already set to “Figure”. We can make a bunch of figure captions without worrying about messing up the table numbering.

fig_nums("apple", "Relationship between the number of apple seeds and the size of the apple.")
## [1] "Figure  1: Relationship between the number of apple seeds and the size of the apple."
fig_nums("milk_fat", "Average percentage of fat in milk from various animals.")
## [1] "Figure  2: Average percentage of fat in milk from various animals."
fig_nums("tree_height", "Distribution of heights in common restinga tree species.")
## [1] "Figure  3: Distribution of heights in common restinga tree species."

And now some more tables:

table_nums("world_pop", "World populations ordered from greatest to least.")
## [1] "Table  3: World populations ordered from greatest to least."
table_nums("dolphins", "List of dolphin species and their brain sizes.")
## [1] "Table  4: List of dolphin species and their brain sizes."

### Citing

Other than displaying full captions, you probably will also want to cite your figures and tables, without the caption, in your text. You can do this by setting the display argument to cite.

fig_nums("milk_fat", display = "cite")
## [1] "Figure  2"

This works particularly well using an inline code chunk:

"There was no significant trend in milk fat between gramnivores" (r fig_nums("milk_fat", display = "cite")).

Which looks like:

There was no significant trend in milk fat between gramnivores (Figure 2).

It is possible that you will want to cite the figure before actually displaying the figure. This is not a problem, you can create the citation with or without a caption, and captioner will automatically figure out the numbering. The numbering is designated the first time a figure with that keyword is encountered, whether it’s a citation or a full caption.

fig_nums("snuff",  display = "cite")
## [1] "Figure  4"
fig_nums("bounce", "Bounce height (cm) of balls made of various types of rubber.")
## [1] "Figure  5: Bounce height (cm) of balls made of various types of rubber."
fig_nums("snuff",  "Average size of snuff boxes used from 1808 to 1908.")
## [1] "Figure  4: Average size of snuff boxes used from 1808 to 1908."
fig_nums("bounce", display = "cite")
## [1] "Figure  5"

If you find the code for citing cumbersome, you can shorten it by using partial from the package pryr. This allows you to preemptively fill in some of the parameters of your captioner() function.

For example: citef <- partial(fig_nums, display = "cite")

Then: citef("bounce")

### Implementing hierarchical numbering

If you want figure numbers with more depth, say if you have a figure with subfigures, or have figure numbers attached to sections, you can implement hierarchical numbering. This will give you, for example, something like “Figure 1.1.1”.

figs_2 <- captioner(levels = 3, type = c("n", "n", "n"), infix = "-")
figs_2("A", "The letter A in several typefaces.")
## [1] "Figure  1-1-1: The letter A in several typefaces."

The three new parameters tell captioner how many subsets of numbers you want (levels), whether you want a number or a character for each (type), and what you want separating them (infix). For type, the choices are "n" - a number, "c" - a lowercase character, or "C" - an uppercase character. If your vector is too short, or if you choose not to supply any type, captioner will automatically fill in the missing types with numbers. The default infix is ., but you can choose anything you want.

Normally, a call to figs_2 will only increment the final number or character in your figure number. If you want to increment an earlier value, there are two ways. First, you can set the parameter level inside of figs_2. level gives the number corresponding to which value you want incremented. For example, if you want to bump up from 1.1.1 to 1.2.1:

figs_2("B", display = "cite", level = 2)
## [1] "Figure  1-2-1"

The second way to do this is to use the function bump, introduced in captioner version 2.0. If you have a document with many chapters or sections, bump may be more convenient because it is not connected to a specific figure. Instead, you can place it after your section heading, and all subsequent figures will have the bumped up numbering.

bump takes as parameters your captioner function, and a numbering indicating which level you want bumped:

bump(figs_2, level = 1)

figs_2("C", "The letter C shown in fixed-width fonts.")
## [1] "Figure  2-1-1: The letter C shown in fixed-width fonts."


text:
# Closing duplicate questions

Recently, I posted a question (this one) and received some helpful answers. However, the answers did not help me solve my issue. So, I posted another question (this one) explaining my thinking and sources of confusion.

However, my question was quickly closed (luckily, I got the necessary answer before that). Looking at the duplicate information, it says:

If those answers do not fully address your question, please edit this question to explain how it is different $\textbf{or ask a new question}$.

I prefer to ask a new question explaining my thinking, rather than hoping an old question will be rediscovered and answered after a day, even with my edits. Since the repeated question received a negative response, could someone clarify why the implied rules for duplicate questions are not the same as the written rules?

Just to clarify, I am very grateful to everyone who takes the time to help me, and I just wanted to clarify the policy for my understanding.

• BTW you do not have to use MathJax to get bold/italics, you can use markdown. For example, instead of $\textbf{or ask a new question}$ (which renders as $\textbf{or ask a new question}$) you could have written **or ask a new question** (which renders as or ask a new question). – Martin Sleziak Mar 4 '14 at 7:47


text:
2009-12-18

# Simulating “make distclean” in SCons

SCons provides an automatic “clean” target out of the box — just run scons -c, and SCons will delete all of the objects that it knows how to build. This is a very useful feature; however, there are two main missing features that I want to add to my build scripts. First, I want to be able to delete all of the temporary files SCons uses, such as its configuration cache and any files I use to store variable values. These aren’t included in the default list of the files to clean up. Second, I want more control over which items are deleted by default, when you specify scons -c without any targets. I’ll describe my solution to the first problem in this post. I’ll write up the second problem in another post.

## Deleting SCons’s temporary files

This feature is akin to the make distclean target that Automake puts into the Makefiles that it generates. This differs from make clean; make clean is intended to delete all of the build products, but leave behind the results of the configure step, whereas make distclean is supposed delete everything, returning the source tree to the same state as when you’d just unpacked the tarball.

The scons -c command is analogous to make clean, and requires no setup. It will automatically delete any of the build products that are created by running scons. There are several cache files that SCons creates, however, and it would be nice to have an equivalent to make distclean. This is especially useful when developing a new Configuration check, for instance — if you make a change to the test, you want to be able to (easily) force SCons to ignore any cached results, and try all of the tests again.

This is actually fairly easy to set up, assuming you know the list of temporary files that SCons will create. You can add the following rule to your top-level SConstruct file:

env.Clean("distclean",
[
".sconsign.dblite",
".sconf_temp",
"config.log",
])

As far as I can tell, these three files are always created by SCons. To delete these files, you simply run scons -c distclean. Because we’ve defined the target using Clean, it will only be run when you pass in the -c option to scons.

Since we’re putting together the file list manually, you should make sure to add any additional cache files that your SCons scripts use. For instance, I’m using some Variable options, which I store into a file called .scons.vars. (This means that the user doesn’t have to type them in with every invocation of scons.) By using these variables, I have to add another entry to the distclean target:

vars = Variables('.scons.vars', ARGUMENTS)
# ...define a bunch of variables
vars.Update(env)
vars.Save(".scons.vars", env)

env.Clean("distclean", [".scons.vars"])

Note how, just like with any SCons target, I can define the distclean target multiple times. SCons will take care of merging them into a single action, deleting all of the specified files when you run scons -c distclean.


text:
# Need help drawing multivews (25) (28)

###### Question:

need help drawing multivews

(25) (28)

#### Similar Solved Questions

##### This module discussed national priorities for health care and how meaningful use strategies could help move...
This module discussed national priorities for health care and how meaningful use strategies could help move these efforts forward. Explain meaningful use and the implementation stages of meaningful use. Discuss how meaningful use and patient portals have or can directly help you and your family ach...
##### Week 5 worksheet L. Explain why aa do. reay is the gsivernment budget deficit could lead...
Week 5 worksheet L. Explain why aa do. reay is the gsivernment budget deficit could lead to an increase in invest ment by firns. 2. Suppose that beca tse of a rising price level, consumer starts carrying more of their wealth as cash, in order to curty ouk trvsactions, and thus are less willing to pu...
##### 2/3 of all your books are fiction. 1/6 of those are historical fiction. What fraction of all your books are historical fiction?
2/3 of all your books are fiction. 1/6 of those are historical fiction. What fraction of all your books are historical fiction?...
##### Problem 2: Remember effic or other air pollution controls, eff removed'/'mass of pollutant going ...
Problem 2: Remember effic or other air pollution controls, eff removed'/'mass of pollutant going in". Coal can have different energy intensities and is ciency is power out/energy in for power plants. For Scrubbers controls, efficiency refers to the percentage of "mass of pollutant ra...
##### I am unsure if my answer is correct. 2 attempts left Check my work Click the "draw structure" button to launch the drawing utility. Using the curved arrow to guide your reasoning, draw the...
I am unsure if my answer is correct. 2 attempts left Check my work Click the "draw structure" button to launch the drawing utility. Using the curved arrow to guide your reasoning, draw the missing produet of the following dissociation. Include formal charges and unshared electron pairs. ...
##### 60 ANALO47% Determining che Formula ofan Ionic Hydrate Gravímerically 3. Upon being heated, calcium oxalate monohydrate,...
60 ANALO47% Determining che Formula ofan Ionic Hydrate Gravímerically 3. Upon being heated, calcium oxalate monohydrate, CaC,o, H20, undergoes a series of temperature- Eq. 6) (Eq. 7) (Eq. 8) A student paid little attention to the size of his burner flame while heating a 0.979-g sample of rela...
##### When forming portfolio with assets of different risk and return profile, which of the following is...
When forming portfolio with assets of different risk and return profile, which of the following is the advantage of the portfolio compare to individual asset investment? reduced risk from the portfolio relative to the individual assets enhanced return from the portfolio over the individu...
##### If the payment term is planned to be 20% payment made at least 10days before shipping...
If the payment term is planned to be 20% payment made at least 10days before shipping by T/T. 80% payment made by a credit be available with any bank by negotiation at sight. How can a seller apply for trade financing Question 6: The seller want to apply for forfuaiting as the buyer wish to make...
##### The accounts and balances for Babysitting Co. on June 1 are provided below. Cash 10,200 Tees...
The accounts and balances for Babysitting Co. on June 1 are provided below. Cash 10,200 Tees Income -0. Accounts 1,700 Rent expense -0- receivable Utilities office equipment 5,100 -D- expense Supplies 1,100 salaries expense --- Accounts payable 4,100 Kelly Connor, Capital 14,000 Kelly Connor, Drawin...
##### Testbank, Question 073. Provide the structures of the products in each step of the following reaction...
Testbank, Question 073. Provide the structures of the products in each step of the following reaction sequence. Testbank, Question 073 am Get help answering Molecular Dra Provide the structures of the products in each step of the following reaction sequence. 1. ВНз (CH3)2NH ...
##### Wondering if this is the correct way to solve this problem 14 of Soin. when 1.000...
wondering if this is the correct way to solve this problem 14 of Soin. when 1.000 of O.SDOM acetic acid ? NaOH is dissolved in 0.00 TL pka - 4.74 of acetic acid NaOH + CH3COOH Igx Imol CH₃COONa+H2O - 39.997 = 0.025 mol 0.SOOM * 0.1L = 0.05 mol acest acid NaoH 0.05-0.025 = 0.025 mol excess NaOH...
Chavez Company most recently reconciled its bank statement and book balances of cash on August 31 and it reported two checks outstanding, No. 5888 for $1,095 and No. 5893 for$516. Check No. 5893 was still outstanding as of September 30. The following information is available for its September 30 re...