RE: Units of Measure for use in Math-ML datasets
Greetings [note that by default replies go to the poster - not the list]: In JSBSim we are addressing this in our own way (at the moment), programmatically using an STL map (indexed by STL strings) to index conversion factors like this: convert["M"]["FT"] = 3.2808399; convert["FT"]["M"] = 1.0/convert["M"]["FT"]; convert["M2"]["FT2"] = convert["M"]["FT"]*convert["M"]["FT"]; convert["FT2"]["M2"] = 1.0/convert["M2"]["FT2"]; convert["FT"]["IN"] = 12.0; convert["IN"]["FT"] = 1.0/convert["FT"]["IN"]; convert["LBS"]["KG"] = 0.45359237; convert["KG"]["LBS"] = 1.0/convert["LBS"]["KG"]; convert["SLUG*FT2"]["KG*M2"] = 1.35594; convert["KG*M2"]["SLUG*FT2"] = 1.0/convert["SLUG*FT2"]["KG*M2"]; convert["RAD"]["DEG"] = 360.0/(2.0*3.1415926); convert["DEG"]["RAD"] = 1.0/convert["RAD"]["DEG"]; convert["LBS/FT"]["N/M"] = 14.5939; convert["LBS/FT/SEC"]["N/M/SEC"] = 14.5939; convert["N/M"]["LBS/FT"] = 1.0/convert["LBS/FT"]["N/M"]; convert["N/M/SEC"]["LBS/FT/SEC"] = 1.0/convert["LBS/FT/SEC"]["N/M/SEC"]; convert["M"]["M"] = 1.00; convert["FT"]["FT"] = 1.00; convert["IN"]["IN"] = 1.00; convert["IN3"]["IN3"] = 1.00; convert["DEG"]["DEG"] = 1.00; convert["RAD"]["RAD"] = 1.00; convert["M2"]["M2"] = 1.00; convert["FT2"]["FT2"] = 1.00; convert["KG*M2"]["KG*M2"] = 1.00; convert["SLUG*FT2"]["SLUG*FT2"] = 1.00; convert["KG"]["KG"] = 1.00; convert["LBS"]["LBS"] = 1.00; convert["LBS/FT"]["LBS/FT"] = 1.00; convert["N/M"]["N/M"] = 1.00; convert["LBS/FT/SEC"]["LBS/FT/SEC"] = 1.00; convert["N/M/SEC"]["N/M/SEC"] = 1.00; convert["PSI"]["PSI"] = 1.00; convert["INHG"]["INHG"] = 1.00; convert["HP"]["HP"] = 1.00; Since this is only done at initialization time, CPU usage is not so critical for us. I'd be interested in hearing more about standard unit abbrev.s, though. Jon Berndt
Re: Units of Measure for use in Math-ML datasets
Title: Re: Units of Measure for use in Math-ML datasets At 12:14 PM +1100 12/17/04, Brian, Geoff wrote: Hi all, I noticed in the DAVE-ML reference that the issue of units-of-measure notation is still to be finalised. I have been looking at this for our flight dynamic / simulation modelling here in DSTO, and have found that a number of the proposed standards have conflicting information for units of measure, both between standards and within individual standards. As a result, I have prepared a list of units of measure for use with aircraft modelling here in DSTO (see attached). A difference I have adopted from general conventions is the use of negative powers to represent divisor units irrespective of whether the unit of measure is metric or imperial (eg. ft s-1 instead of ft/s). I have found this is simpler when defining something like ft s-2 instead of ft/s/s or ft/s2. I thought that this might be useful as a starting point for defining a units-of-measure notation for Dave-ML and welcome any comments. The references I have used for compiling the list were: "Standards for the Exchange of Simulation Modeling Data", Preliminary Draft, 9 June 1997, AIAA Modeling and Simulation Technical Committee. "SI Units Dimensional Analysis &, Chapter 8 Figure -- Conversion Tables", McMahonlines, MathTech Reference Series. http://www.unc.edu/~rowlett/units/index.html hope you are having an enjoyable lead up to the end of the year. Regards Mr Geoff Brian Aircraft Flight Dynamics and Performance Engineer. Air Vehicles Division, Defence Science and Technology Organisation. Brian, Thanks for the legwork. This may make an excellent starting point for satisfying the need to standardize units of measure abbreviations. I'd like to hear from other interested users on this important issue. Brian is suggesting writing "ft s-1" instead of "ft/s" for velocity in English units... -- Bruce P.S. Merry Christmas to those that celebrate it (like me). P.P.S. When does Australia celebrate it (*grin*)? Do you sing "Sleigh Ride" or "Dreaming of a White Christmas"? -- bjax -- Bruce Jackson <[EMAIL PROTECTED]> Guidance and Controls Branch 18C West Taylor Street MS 132 Research & Technology Directorate NASA Langley Research Center Hampton, Virginia 23681 More info about DAVE-ML: Simulation standards discussion listserv mailto:simstds@larc.nasa.gov
Units of Measure for use in Math-ML datasets
Title: Re: Use of Math-ML with DAVEfunc Version 1.7b1 Hi all, I noticed in the DAVE-ML reference that the issue of units-of-measure notation is still to be finalised. I have been looking at this for our flight dynamic / simulation modelling here in DSTO, and have found that a number of the proposed standards have conflicting information for units of measure, both between standards and within individual standards. As a result, I have prepared a list of units of measure for use with aircraft modelling here in DSTO (see attached). A difference I have adopted from general conventions is the use of negative powers to represent divisor units irrespective of whether the unit of measure is metric or imperial (eg. ft s-1 instead of ft/s). I have found this is simpler when defining something like ft s-2 instead of ft/s/s or ft/s2. I thought that this might be useful as a starting point for defining a units-of-measure notation for Dave-ML and welcome any comments. The references I have used for compiling the list were: "Standards for the Exchange of Simulation Modeling Data", Preliminary Draft, 9 June 1997, AIAA Modeling and Simulation Technical Committee. "SI Units Dimensional Analysis &, Chapter 8 Figure -- Conversion Tables", McMahonlines, MathTech Reference Series. http://www.unc.edu/~rowlett/units/index.html hope you are having an enjoyable lead up to the end of the year. Regards Mr Geoff Brian Aircraft Flight Dynamics and Performance Engineer. Air Vehicles Division, Defence Science and Technology Organisation. Ph. (03) 9626 7318, Fax (03) 9626 7085. e-mail: [EMAIL PROTECTED] Title: Flight Systems Units of Measure Guidelines Flight Systems Units of Measure Guidelines. $Revision: 1.1$ $Date: 2004/10/26$ Written by: Geoff Brian ([EMAIL PROTECTED]) Table of Contents Introduction Comments Units of Measure Abbreviations References Introduction This document, although not exhaustive, lists abbreviations for units of measure common in the Aircraft Modelling and Simulation community. Aircraft flight simulations and models compute the behaviour of the aircraft subject to stimuli such as flight control system inputs and environments influences. They also rely on a representation of the physical properties of the aircraft such as its aerodynamics, propulsion system and mass properties. Data detailing the inputs and outputs from simulations, as well as the physical properties of the aircraft, have different units of measure, and also may be mixed between Système Interantionale (SI) units and Imperial units. This guideline presents the units of measure for data utilised by aircraft simulations and models developed by Flight Systems, Air Vehicles Division, DSTO. The Flight Systems Units of Measure Guideline is based on the AIAA Modeling and Simulation Technical Committee "Standards for the Exchange of Simulation Modeling Data -- Preliminary Draft", [1]. Comments Data may have a base unit of measure, as shown in following table, or may be a combination of units; for example, metre: m or acceleration: m s-2. The prefix abbreviations are applied to the base unit of measure abbreviation, and scale the data using values in the comment box; for example, millimetre: mm = 10-3 m For data that have a combined unit of measure, they will be defined using base units elements separated by a blank space; for example, fuel flow rate: l s-1 Divisor units of measure are represented by the unit abbreviation raised to the equivalent negative power; for example, feet per second is represented as ft s-1 Velocity is generally represented using a combined unit of measure; for example, m s-1. However, the knot is a recognised measure in the aviation community and thus included. Units of Measure Abbreviations SI - Système Interantionale Measure Abbreviation Comments General non-dimensional ND Used if non-dimensional parameter Prefix 2 tera T 1012 * parameter giga G 109 * parameter mega M 106 * parameter kilo k 103 * parameter deci d 10-1 * parameter centi c 10-2 * parameter milli m 10-3 * parameter Time Solar year yr Solar day day hour h minute min second s SI Standard Length metres m SI S
