Units of Measurement to Be Used in Air and Ground Operations
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Db Math Marco Zennaro Ermanno Pietrosemoli Goals
dB Math Marco Zennaro Ermanno Pietrosemoli Goals ‣ Electromagnetic waves carry power measured in milliwatts. ‣ Decibels (dB) use a relative logarithmic relationship to reduce multiplication to simple addition. ‣ You can simplify common radio calculations by using dBm instead of mW, and dB to represent variations of power. ‣ It is simpler to solve radio calculations in your head by using dB. 2 Power ‣ Any electromagnetic wave carries energy - we can feel that when we enjoy (or suffer from) the warmth of the sun. The amount of energy received in a certain amount of time is called power. ‣ The electric field is measured in V/m (volts per meter), the power contained within it is proportional to the square of the electric field: 2 P ~ E ‣ The unit of power is the watt (W). For wireless work, the milliwatt (mW) is usually a more convenient unit. 3 Gain and Loss ‣ If the amplitude of an electromagnetic wave increases, its power increases. This increase in power is called a gain. ‣ If the amplitude decreases, its power decreases. This decrease in power is called a loss. ‣ When designing communication links, you try to maximize the gains while minimizing any losses. 4 Intro to dB ‣ Decibels are a relative measurement unit unlike the absolute measurement of milliwatts. ‣ The decibel (dB) is 10 times the decimal logarithm of the ratio between two values of a variable. The calculation of decibels uses a logarithm to allow very large or very small relations to be represented with a conveniently small number. ‣ On the logarithmic scale, the reference cannot be zero because the log of zero does not exist! 5 Why do we use dB? ‣ Power does not fade in a linear manner, but inversely as the square of the distance. -
Appendix A: Symbols and Prefixes
Appendix A: Symbols and Prefixes (Appendix A last revised November 2020) This appendix of the Author's Kit provides recommendations on prefixes, unit symbols and abbreviations, and factors for conversion into units of the International System. Prefixes Recommended prefixes indicating decimal multiples or submultiples of units and their symbols are as follows: Multiple Prefix Abbreviation 1024 yotta Y 1021 zetta Z 1018 exa E 1015 peta P 1012 tera T 109 giga G 106 mega M 103 kilo k 102 hecto h 10 deka da 10-1 deci d 10-2 centi c 10-3 milli m 10-6 micro μ 10-9 nano n 10-12 pico p 10-15 femto f 10-18 atto a 10-21 zepto z 10-24 yocto y Avoid using compound prefixes, such as micromicro for pico and kilomega for giga. The abbreviation of a prefix is considered to be combined with the abbreviation/symbol to which it is directly attached, forming with it a new unit symbol, which can be raised to a positive or negative power and which can be combined with other unit abbreviations/symbols to form abbreviations/symbols for compound units. For example: 1 cm3 = (10-2 m)3 = 10-6 m3 1 μs-1 = (10-6 s)-1 = 106 s-1 1 mm2/s = (10-3 m)2/s = 10-6 m2/s Abbreviations and Symbols Whenever possible, avoid using abbreviations and symbols in paragraph text; however, when it is deemed necessary to use such, define all but the most common at first use. The following is a recommended list of abbreviations/symbols for some important units. -
Representation of Derived Units in Unitsml (Revised December 8, 2006)
Representation of Derived Units in UnitsML (revised December 8, 2006) Peter J. Linstrom∗ December 8, 2006 ∗phone: (301) 975-5422,DRAFT e-mail: [email protected] 1 INTRODUCTION 12/8/06 Contents 1 Introduction 1 2 Why this convention is needed 2 3 Information needed to define a unit 3 4 Proposed XML encoding 4 5 Important conventions 7 6 Potential problems 8 7 Possible alternatives 10 A Multiplicative prefixes 12 B SI units and units acceptable for use with the SI 14 C non-SI Units 19 1 Introduction This document describes a proposed convention for defining derived units in terms of their base units. This convention is intended for use in the UnitsML markup language to allow a precise definition of a wide range of units. The goal of this convention is to improve interoperability among applications and databases which use derived units based on commonly encountered base units. It is understoodDRAFT that not all units can be represented using this convention. It is, however, Representation of Derived Units in UnitsML (revised December 8, 2006) Page 1 2 WHY THIS CONVENTION IS NEEDED 12/8/06 anticipated that a wide range of scientific and engineering units of measure can be represented with this convention. The convention consists of representing the unit in terms of multiplicative combinations of base units. For example the unit centimeter per second squared would be represented in terms of the following: 1. The unit meter with the prefix centi raised to the power 1. 2. The unit second raised to the power −2. -
Astm Metric Practice Guide
National Bureau of Standards Library, E-01 Admrn. Bldg. A111DO cmfl4S - m 2 0 1967 METRIC PRACTICE GUIDE NATL INST OF STANDARDS & TECH R.I.C. All100991845 /NBS handbook QC1 .U51 V102;1967 C.1 NBS-PUB-C 1934 U. S. DEPARTMENT OF COMMERCE NATIONAL OUREAU OF STANDARDS HANDBOOK 102 THE NATIONAL BUREAU OF STANDARDS The National Bureau of Standards 1 provides measurement and technical information services essential to the efficiency and effectiveness of the work of the Nation’s scientists and engineers. The Bureau serves also as a focal point in the Federal Government for assuring maximum application of the physical and engineering sciences to the advancement of technology in industry and commerce. To accomplish this mission, the Bureau is organized into three institutes covering broad program areas of research and services: THE INSTITUTE FOR BASIC STANDARDS . provides the central basis within the United States for a complete and consistent system of physical measurements, coordinates that system with the measurement systems of other nations, and furnishes essential services leading to accurate and uniform physical measurements throughout the Nation’s scientific com¬ munity, industry, and commerce. This Institute comprises a series of divisions, each serving a classical subject matter area: —Applied Mathematics — Electricity—Metrology — Mechanics — Heat — Atomic Physics—Physical Chemistry—Radiation Physics—Laboratory Astrophysics2—Radio Standards Laboratory,2 which includes Radio Standards Physics and Radio Standards Engineering—Office of Standard Reference Data. THE INSTITUTE FOR MATERIALS RESEARCH . conducts materials research and provides associated materials services including mainly reference materials and data on the properties of materials. Beyond its direct interest to the Nation’s scientists and engineers, this Institute yields services which are essential to the advancement of technology in industry and commerce. -
Electric Units and Standards
DEPARTMENT OF COMMERCE OF THE Bureau of Standards S. W. STRATTON, Director No. 60 ELECTRIC UNITS AND STANDARDS list Edition 1 Issued September 25. 1916 WASHINGTON GOVERNMENT PRINTING OFFICE DEPARTMENT OF COMMERCE Circular OF THE Bureau of Standards S. W. STRATTON, Director No. 60 ELECTRIC UNITS AND STANDARDS [1st Edition] Issued September 25, 1916 WASHINGTON GOVERNMENT PRINTING OFFICE 1916 ADDITIONAL COPIES OF THIS PUBLICATION MAY BE PROCURED FROM THE SUPERINTENDENT OF DOCUMENTS GOVERNMENT PRINTING OFFICE WASHINGTON, D. C. AT 15 CENTS PER COPY A complete list of the Bureau’s publications may be obtained free of charge on application to the Bureau of Standards, Washington, D. C. ELECTRIC UNITS AND STANDARDS CONTENTS Page I. The systems of units 4 1. Units and standards in general 4 2. The electrostatic and electromagnetic systems 8 () The numerically different systems of units 12 () Gaussian systems, and ratios of the units 13 “ ’ (c) Practical ’ electromagnetic units 15 3. The international electric units 16 II. Evolution of present system of concrete standards 18 1. Early electric standards 18 2. Basis of present laws 22 3. Progress since 1893 24 III. Units and standards of the principal electric quantities 29 1. Resistance 29 () International ohm 29 Definition 29 Mercury standards 30 Secondary standards 31 () Resistance standards in practice 31 (c) Absolute ohm 32 2. Current 33 (a) International ampere 33 Definition 34 The silver voltameter 35 ( b ) Resistance standards used in current measurement 36 (c) Absolute ampere 37 3. Electromotive force 38 (a) International volt 38 Definition 39 Weston normal cell 39 (b) Portable Weston cells 41 (c) Absolute and semiabsolute volt 42 4. -
Decibels, Phons, and Sones
Decibels, Phons, and Sones The rate at which sound energy reaches a Table 1: deciBel Ratings of Several Sounds given cross-sectional area is known as the Sound Source Intensity deciBel sound intensity. There is an abnormally Weakest Sound Heard 1 x 10-12 W/m2 0.0 large range of intensities over which Rustling Leaves 1 x 10-11 W/m2 10.0 humans can hear. Given the large range, it Quiet Library 1 x 10-9 W/m2 30.0 is common to express the sound intensity Average Home 1 x 10-7 W/m2 50.0 using a logarithmic scale known as the Normal Conversation 1 x 10-6 W/m2 60.0 decibel scale. By measuring the intensity -4 2 level of a given sound with a meter, the Phone Dial Tone 1 x 10 W/m 80.0 -3 2 deciBel rating can be determined. Truck Traffic 1 x 10 W/m 90.0 Intensity values and decibel ratings for Chainsaw, 1 m away 1 x 10-1 W/m2 110.0 several sound sources listed in Table 1. The decibel scale and the intensity values it is based on is an objective measure of a sound. While intensities and deciBels (dB) are measurable, the loudness of a sound is subjective. Sound loudness varies from person to person. Furthermore, sounds with equal intensities but different frequencies are perceived by the same person to have unequal loudness. For instance, a 60 dB sound with a frequency of 1000 Hz sounds louder than a 60 dB sound with a frequency of 500 Hz. -
Guide for the Use of the International System of Units (SI)
Guide for the Use of the International System of Units (SI) m kg s cd SI mol K A NIST Special Publication 811 2008 Edition Ambler Thompson and Barry N. Taylor NIST Special Publication 811 2008 Edition Guide for the Use of the International System of Units (SI) Ambler Thompson Technology Services and Barry N. Taylor Physics Laboratory National Institute of Standards and Technology Gaithersburg, MD 20899 (Supersedes NIST Special Publication 811, 1995 Edition, April 1995) March 2008 U.S. Department of Commerce Carlos M. Gutierrez, Secretary National Institute of Standards and Technology James M. Turner, Acting Director National Institute of Standards and Technology Special Publication 811, 2008 Edition (Supersedes NIST Special Publication 811, April 1995 Edition) Natl. Inst. Stand. Technol. Spec. Publ. 811, 2008 Ed., 85 pages (March 2008; 2nd printing November 2008) CODEN: NSPUE3 Note on 2nd printing: This 2nd printing dated November 2008 of NIST SP811 corrects a number of minor typographical errors present in the 1st printing dated March 2008. Guide for the Use of the International System of Units (SI) Preface The International System of Units, universally abbreviated SI (from the French Le Système International d’Unités), is the modern metric system of measurement. Long the dominant measurement system used in science, the SI is becoming the dominant measurement system used in international commerce. The Omnibus Trade and Competitiveness Act of August 1988 [Public Law (PL) 100-418] changed the name of the National Bureau of Standards (NBS) to the National Institute of Standards and Technology (NIST) and gave to NIST the added task of helping U.S. -
Traffic and Road Sign Recognition
Traffic and Road Sign Recognition Hasan Fleyeh This thesis is submitted in fulfilment of the requirements of Napier University for the degree of Doctor of Philosophy July 2008 Abstract This thesis presents a system to recognise and classify road and traffic signs for the purpose of developing an inventory of them which could assist the highway engineers’ tasks of updating and maintaining them. It uses images taken by a camera from a moving vehicle. The system is based on three major stages: colour segmentation, recognition, and classification. Four colour segmentation algorithms are developed and tested. They are a shadow and highlight invariant, a dynamic threshold, a modification of de la Escalera’s algorithm and a Fuzzy colour segmentation algorithm. All algorithms are tested using hundreds of images and the shadow-highlight invariant algorithm is eventually chosen as the best performer. This is because it is immune to shadows and highlights. It is also robust as it was tested in different lighting conditions, weather conditions, and times of the day. Approximately 97% successful segmentation rate was achieved using this algorithm. Recognition of traffic signs is carried out using a fuzzy shape recogniser. Based on four shape measures - the rectangularity, triangularity, ellipticity, and octagonality, fuzzy rules were developed to determine the shape of the sign. Among these shape measures octangonality has been introduced in this research. The final decision of the recogniser is based on the combination of both the colour and shape of the sign. The recogniser was tested in a variety of testing conditions giving an overall performance of approximately 88%. -
SI and CGS Units in Electromagnetism
SI and CGS Units in Electromagnetism Jim Napolitano January 7, 2010 These notes are meant to accompany the course Electromagnetic Theory for the Spring 2010 term at RPI. The course will use CGS units, as does our textbook Classical Electro- dynamics, 2nd Ed. by Hans Ohanian. Up to this point, however, most students have used the International System of Units (SI, also known as MKSA) for mechanics, electricity and magnetism. (I believe it is easy to argue that CGS is more appropriate for teaching elec- tromagnetism to physics students.) These notes are meant to smooth the transition, and to augment the discussion in Appendix 2 of your textbook. The base units1 for mechanics in SI are the meter, kilogram, and second (i.e. \MKS") whereas in CGS they are the centimeter, gram, and second. Conversion between these base units and all the derived units are quite simply given by an appropriate power of 10. For electromagnetism, SI adds a new base unit, the Ampere (\A"). This leads to a world of complications when converting between SI and CGS. Many of these complications are philosophical, but this note does not discuss such issues. For a good, if a bit flippant, on- line discussion see http://info.ee.surrey.ac.uk/Workshop/advice/coils/unit systems/; for a more scholarly article, see \On Electric and Magnetic Units and Dimensions", by R. T. Birge, The American Physics Teacher, 2(1934)41. Electromagnetism: A Preview Electricity and magnetism are not separate phenomena. They are different manifestations of the same phenomenon, called electromagnetism. One requires the application of special relativity to see how electricity and magnetism are united. -
Appendix H: Common Units and Conversions Appendices 215
Appendix H: Common Units and Conversions Appendices 215 Appendix H: Common Units and Conversions Temperature Length Fahrenheit to Celsius: °C = (°F-32)/1.8 1 micrometer (sometimes referred centimeter (cm) meter (m) inch (in) Celsius to Fahrenheit: °F = (1.8 × °C) + 32 to as micron) = 10-6 m Fahrenheit to Kelvin: convert °F to °C, then add 273.15 centimeter (cm) 1 1.000 × 10–2 0.3937 -3 Celsius to Kelvin: add 273.15 meter (m) 100 1 39.37 1 mil = 10 in Volume inch (in) 2.540 2.540 × 10–2 1 –3 3 1 liter (l) = 1.000 × 10 cubic meters (m ) = 61.02 Area cubic inches (in3) cm2 m2 in2 circ mil Mass cm2 1 10–4 0.1550 1.974 × 105 1 kilogram (kg) = 1000 grams (g) = 2.205 pounds (lb) m2 104 1 1550 1.974 × 109 Force in2 6.452 6.452 × 10–4 1 1.273 × 106 1 newton (N) = 0.2248 pounds (lb) circ mil 5.067 × 10–6 5.067 × 10–10 7.854 × 10–7 1 Electric resistivity Pressure 1 micro-ohm-centimeter (µΩ·cm) pascal (Pa) millibar (mbar) torr (Torr) atmosphere (atm) psi (lbf/in2) = 1.000 × 10–6 ohm-centimeter (Ω·cm) –2 –3 –6 –4 = 1.000 × 10–8 ohm-meter (Ω·m) pascal (Pa) 1 1.000 × 10 7.501 × 10 9.868 × 10 1.450 × 10 = 6.015 ohm-circular mil per foot (Ω·circ mil/ft) millibar (mbar) 1.000 × 102 1 7.502 × 10–1 9.868 × 10–4 1.450 × 10–2 2 0 –3 –2 Heat flow rate torr (Torr) 1.333 × 10 1.333 × 10 1 1.316 × 10 1.934 × 10 5 3 2 1 1 watt (W) = 3.413 Btu/h atmosphere (atm) 1.013 × 10 1.013 × 10 7.600 × 10 1 1.470 × 10 1 British thermal unit per hour (Btu/h) = 0.2930 W psi (lbf/in2) 6.897 × 103 6.895 × 101 5.172 × 101 6.850 × 10–2 1 1 torr (Torr) = 133.332 pascal (Pa) 1 pascal (Pa) = 0.01 millibar (mbar) 1.33 millibar (mbar) 0.007501 torr (Torr) –6 A Note on SI 0.001316 atmosphere (atm) 9.87 × 10 atmosphere (atm) 2 –4 2 The values in this catalog are expressed in 0.01934 psi (lbf/in ) 1.45 × 10 psi (lbf/in ) International System of Units, or SI (from the Magnetic induction B French Le Système International d’Unités). -
Automatic Irrigation : Sensors and System
South Dakota State University Open PRAIRIE: Open Public Research Access Institutional Repository and Information Exchange Electronic Theses and Dissertations 1970 Automatic Irrigation : Sensors and System Herman G. Hamre Follow this and additional works at: https://openprairie.sdstate.edu/etd Recommended Citation Hamre, Herman G., "Automatic Irrigation : Sensors and System" (1970). Electronic Theses and Dissertations. 3780. https://openprairie.sdstate.edu/etd/3780 This Thesis - Open Access is brought to you for free and open access by Open PRAIRIE: Open Public Research Access Institutional Repository and Information Exchange. It has been accepted for inclusion in Electronic Theses and Dissertations by an authorized administrator of Open PRAIRIE: Open Public Research Access Institutional Repository and Information Exchange. For more information, please contact [email protected]. AUTOMATIC IRRIGATION: SENSORS AND SYSTEM BY HERMAN G. HAMRE A thesis submitted in partial fulfillment of the requirements for the degree Master of Science, Major in Electrical Engineering, South Dakota State University 1970 SOUTH DAKOTA STATE UNIVERSITY LIBRARY AUTOMATIC IRRIGATION: SENSORS AND SYSTEM This thesis is approved as a creditable and independent investi gation by a candidate for the degree, Master of Science, and is accept able as meeting the thesis requirements for this degree, but without implying that the conclusions reached by the candidate are necessarily the conclusions of the major department. �--- -"""'" _ _ -���--- - _ _ _ _____ -A>� - 7 7 T b � s/./ifjvisor ate Head, Electrical -r-oate Engineering Department ACKNOWLE GEMENTS The author wishes to express his sincere appreciation to Dr. A. J. Kurtenbach for his patient guidance and helpful suggestions, and to the Water Resources Institute for their support of this research. -
Manual of Style
Manual Of Style 1 MANUAL OF STYLE TABLE OF CONTENTS CHAPTER 1 GENERAL PROVISIONS ...............3 101.0 Scope .............................................. 3 102.0 Codes and Standards..................... 3 103.0 Code Division.................................. 3 104.0 Table of Contents ........................... 4 CHAPTER 2 ADMINISTRATION .........................6 201.0 Administration ................................. 6 202.0 Chapter 2 Definitions ...................... 6 203.0 Referenced Standards Table ......... 6 204.0 Individual Chapter Administrative Text ......................... 6 205.0 Appendices ..................................... 7 206.0 Installation Standards ..................... 7 207.0 Extract Guidelines .......................... 7 208.0 Index ............................................... 9 CHAPTER 3 TECHNICAL STYLE .................... 10 301.0 Technical Style ............................. 10 302.0 Technical Rules ............................ 10 Table 302.3 Possible Unenforceable and Vague Terms ................................ 10 303.0 Health and Safety ........................ 11 304.0 Rules for Mandatory Documents .................................... 11 305.0 Writing Mandatory Requirements ............................... 12 Table 305.0 Typical Mandatory Terms............. 12 CHAPTER 4 EDITORIAL STYLE ..................... 14 401.0 Editorial Style ................................ 14 402.0 Definitions ...................................... 14 403.0 Units of Measure ............................ 15 404.0 Punctuation