Cadastral plotting by similarity transformation

CISM journal ◽  
1988 ◽  
Vol 42 (2) ◽  
pp. 121-125 ◽  
Author(s):  
Roy Gagnon
Keyword(s):  
Numerical Methods ◽  
Complex Number ◽  
Similarity Transformation ◽  
Cost Effective ◽  
Human Interface ◽  
Sources Of Error ◽  
Cadastral Maps ◽  
Numerical Transformation ◽  
Digital Methods ◽  
Many Sources

Cadastral maps generated from digitizing tabloids have too many sources of error to be reliable when plotted at large scales. To improve the 1:1000 cadastral map, three numerical methods were tested during twenty-seven mapping projects. The systems studied were: complex number similarity transformation, simultaneous similarity transformation, and iterative similarity transformation. There were several “human interface” difficulties with the computer routines but all of the programs were found to be reliable, and cost effective. All of the resulting cadastral maps are in daily use. Numerical transformation was found superior to digital methods of cadastral compilation.

scholarly journals Phase Doppler quantification of agricultural spray compared with traditional sampling materials

2017 ◽  
Vol 70 ◽  
pp. 142-151
Author(s):  
R.L. Roten ◽  
S.L. Post ◽  
A. Werner ◽  
M. Safa ◽  
A.J. Hewitt
Keyword(s):  
Fluorescent Dyes ◽  
Droplet Velocity ◽  
Field Phase ◽  
Flux Data ◽  
Sources Of Error ◽  
Close Proximity ◽  
Flux Measurements ◽  
Many Sources

The quantification of spray mass has historically been accomplished by means of fluorescent dyes and various string and ground samplers to capture the dye-laden spray. However, these methods are typically not used in close proximity to orchard sprayers and are prone to many sources of error. The objective of this study was to assess the ability of an in-field phase Doppler (pD) interferometer to quantify spray mass against two common string samplers. Measurements were taken at 0.5 m increments to 4.5 m vertically and 1.0 m increments to 5.0 m downwind from the spray. Converted flux measurements from the strings were compared with those obtained using the pD interferometer. The current pD technology was found to be incapable of collecting equivalent flux data to that obtained from the strings. However, the pD equipment did provide useful data on droplet velocity and size.

scholarly journals Fugitive Methane Emission Reduction Using Gas Turbines

1998 ◽  
Author(s):  
Todd Parker
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Cost Effective ◽  
Process Gas ◽  
Natural Gas Transmission ◽  
Air Intake ◽  
Lean Fuel ◽  
Gas Seals ◽  
Turbo Compressor ◽  
Many Sources

Natural gas transmission systems have many sources of fugitive methane emissions that have been difficult to eliminate. This paper discusses an option for dealing with one such source for operations using turbo-compressor units fitted with dry gas seals. Dry seals rely on a small leakage of process gas to maintain the differential pressure of the process against the atmosphere. The seal leakage ultimately results in waste gas that is emitted to the atmosphere through the primary vent. A simple, cost effective, emission disposal mechanism for this application is to vent the seal gas into the gas turbine’s air intake. Explosion hazards are not created by the resultant ultra-lean fuel/air mixture, and once this mixture reaches the combustion chamber, where sufficient fuel is added to create a flammable mixture, significant oxidation of the seal vent gas is realized. Background of the relevant processes is discussed as well as a review of field test data. Similar applications have been reported [1] for the more generalized purpose of Volatile Organic Compound (VOC) destruction using specialized gas turbine combustor designs. As described herein, existing production gas turbine combustors are quite effective at fugitive methane destruction without specialized combustor designs.

scholarly journals Close-range radar rainfall estimation and error analysis

2016 ◽  
Vol 9 (8) ◽  
pp. 3837-3850 ◽  
Author(s):  
C. Z. van de Beek ◽  
H. Leijnse ◽  
P. Hazenberg ◽  
R. Uijlenhoet
Keyword(s):  
Positive Impact ◽  
Rain Gauge ◽  
Minor Role ◽  
Rainfall Estimation ◽  
Radar Rainfall ◽  
Sources Of Error ◽  
Ground Clutter ◽  
Received Power ◽  
Radar Calibration ◽  
Many Sources

Abstract. Quantitative precipitation estimation (QPE) using ground-based weather radar is affected by many sources of error. The most important of these are (1) radar calibration, (2) ground clutter, (3) wet-radome attenuation, (4) rain-induced attenuation, (5) vertical variability in rain drop size distribution (DSD), (6) non-uniform beam filling and (7) variations in DSD. This study presents an attempt to separate and quantify these sources of error in flat terrain very close to the radar (1–2 km), where (4), (5) and (6) only play a minor role. Other important errors exist, like beam blockage, WLAN interferences and hail contamination and are briefly mentioned, but not considered in the analysis. A 3-day rainfall event (25–27 August 2010) that produced more than 50 mm of precipitation in De Bilt, the Netherlands, is analyzed using radar, rain gauge and disdrometer data. Without any correction, it is found that the radar severely underestimates the total rain amount (by more than 50 %). The calibration of the radar receiver is operationally monitored by analyzing the received power from the sun. This turns out to cause a 1 dB underestimation. The operational clutter filter applied by KNMI is found to incorrectly identify precipitation as clutter, especially at near-zero Doppler velocities. An alternative simple clutter removal scheme using a clear sky clutter map improves the rainfall estimation slightly. To investigate the effect of wet-radome attenuation, stable returns from buildings close to the radar are analyzed. It is shown that this may have caused an underestimation of up to 4 dB. Finally, a disdrometer is used to derive event and intra-event specific Z–R relations due to variations in the observed DSDs. Such variations may result in errors when applying the operational Marshall–Palmer Z–R relation. Correcting for all of these effects has a large positive impact on the radar-derived precipitation estimates and yields a good match between radar QPE and gauge measurements, with a difference of 5–8 %. This shows the potential of radar as a tool for rainfall estimation, especially at close ranges, but also underlines the importance of applying radar correction methods as individual errors can have a large detrimental impact on the QPE performance of the radar.

scholarly journals Global Network Access and Publication of Survey Data

1998 ◽  
Vol 179 ◽  
pp. 480-486
Author(s):  
N.E. White
Keyword(s):  
User Interfaces ◽  
Cost Effective ◽  
Global Network ◽  
The Internet ◽  
Mass Storage ◽  
Network Access ◽  
Multiple User ◽  
Astronomical Surveys ◽  
Effective Manner ◽  
Many Sources

The results of astronomical surveys include 1) catalogs containing anywhere from a few to many million objects, 2) data products used to generate the catalogs (e.g., images or spectra), 3) publications and 4) object based compilations of information from many sources. The ubiquitous growth in the Internet and the dramatic reduction in the cost of mass storage systems now allows instant global access to this information. Astrophysics on-line services have grown up with the Internet, and represent an invaluable resource whose access is a routine part of any research project. Unfortunately users are also faced with searching and accessing multiple sites with different content, access and response methods. There can also be inconsistencies amongst the various systems, which can involve extra effort to resolve. A network-integrated astrophysics system has long been sought because it would remove multiple user interfaces and allow much simpler integration of services. In an era of shrinking budgets, the issue is how to achieve this in a cost effective manner. This review gives an overview of the current situation and discusses the likely evolution towards a network-integrated astrophysics system.

scholarly journals University of Michigan Radiocarbon Dates XI

Radiocarbon ◽  
1966 ◽  
Vol 8 ◽  
pp. 256-285 ◽  
Author(s):  
H. R. Crane ◽  
James B. Griffin
Keyword(s):  
Standard Deviation ◽  
Half Life ◽  
Radiocarbon Dating ◽  
Geiger Counter ◽  
University Of Michigan ◽  
Radiocarbon Dates ◽  
Statistical Errors ◽  
Sources Of Error ◽  
The Many ◽  
Many Sources

The following is a list of dates obtained since the time of the compilation of List X in December 1964. The method is essentially the same as that used for the work described in the previous list. Two CO2-CS2Geiger counter systems are used. The equipment and counting techniques have been described elsewhere (Crane, 1961). The dates and estimates of error in this list follow the practice recommended by the International Radiocarbon Dating Conferences of 1962 and 1965, in that (a) dates are computed on the basis of the Libby half-life, 5570 yr, (b) A.D. 1950 is used as the zero of the age scale, and (c) the errors quoted are the standard deviations obtained from the numbers of counts only. In previous Michigan date lists up to and including VII we have quoted errors at least twice as great as the statistical errors of counting, in order to take account of other errors in the over-all process. If the reader wishes to obtain a standard deviation figure which will allow ample room for the many sources of error in the dating process, we suggest he double the figures that are given in this list.

scholarly journals XIII.—The Strains Produced in Iron, Steel, and Nickel Tubes in the Magnetic Field. Part I.

1897 ◽  
Vol 38 (3) ◽  
pp. 527-555 ◽  
Author(s):  
C. G. Knott
Keyword(s):  
Magnetic Field ◽  
Short Note ◽  
Interesting Phenomenon ◽  
Senior Student ◽  
Sources Of Error ◽  
Physical Laboratory ◽  
The Many ◽  
Many Sources ◽  
The Magnetic Field ◽  
Interior Volume

On July 20th, 1891, I communicated to the Society a short note on the effect of longitudinal magnetisation on the interior volume of iron and nickel tubes (see Proceedings, 1890–91, pp. 315–7). These earliest results of observation of a new and interesting phenomenon in magnetic strains were obtained during my last few months' residence in Japan. In following out the lines of research therein suggested, I have been fortunate in having had placed at my disposal by Professor Tait the resources of the Physical Laboratory of Edinburgh University. I desire here to record my great indebtedness to him for the interest he has taken in the work, and for his many helpful suggestions. In surmounting the many experimental difficulties met with at every turn, I had the invaluable co-operation of Mr A. Shand, a senior student in the Physical Laboratory. Various results obtained since 1892 have been communicated in short notes from time to time (see Proceedings, 1891–2, pp. 85–88, 249–252; 1893–4, pp. 295–7; 1894–5, pp. 334–5; see also B. A. Reports, 1892 and 1893); but it was not possible to regard these as altogether satisfactory. It was only in May of last year (1895) that the many sources of error were finally got rid of, and the apparatus perfected. The present paper deals entirely with the results obtained since then. In these later experiments I was ably assisted by Mr A. C. Smith, a student in the Physical Laboratory.

scholarly journals Close-range radar rainfall estimation and error analysis

2016 ◽  
Author(s):  
Remco van de Beek ◽  
Hidde Leijnse ◽  
Pieter Hazenberg ◽  
Remko Uijlenhoet
Keyword(s):  
Positive Impact ◽  
Rain Gauge ◽  
Minor Role ◽  
Rainfall Estimation ◽  
Radar Rainfall ◽  
Sources Of Error ◽  
Ground Clutter ◽  
Received Power ◽  
Radar Calibration ◽  
Many Sources

Abstract. Quantitative precipitation estimation (QPE) using ground-based weather radar is affected by many sources of error. The most important of these are 1) radar calibration, 2) ground clutter, 3) wet radome attenuation, 4) rain induced attenuation, 5) vertical profile of reflectivity, 6) non-uniform beam filling, and 7) variations in rain drop size distribution (DSD). This study presents an attempt to separate and quantify these sources of error in flat terrain very close to the radar (1–2 km), where 4), 5), and 6) only play a minor role. A 3-day rainfall event (25–27 August 2010) that produced more than 50 mm of precipitation in De Bilt, The Netherlands is analyzed using radar, rain gauge, and disdrometer data. Without any correction it is found that the radar severely underestimates the total rain amount (by more than 50 %). The calibration of the radar receiver is operationally monitored by analyzing the received power from the sun. This turns out to cause a 1 dB of underestimation. The operational clutter filter applied by KNMI is found to incorrectly identify precipitation as clutter, especially at near-zero Doppler velocities. An alternative simple clutter removal scheme using a clear sky clutter map improves the rainfall estimation slightly. To investigate the effect of wet radome attenuation, stable returns from buildings close to the radar are analyzed. It is shown that this may have caused an underestimation of up to 4 dB. Finally, a disdrometer is used to derive event and intra-event specific Z-R relations due to variations in the observed DSDs. Such variations may result in errors when applying the operational Marshall-Palmer Z-R relation. Correcting for all of these effects has a large positive impact on the radar derived precipitation estimates and yields a good match between radar QPE and gauge measurements, with a difference of 5 to 8 %. This shows the potential of radar as a tool for rainfall estimation, especially at close ranges, but also underlines the importance of applying radar correction methods as individual errors can have a large detrimental impact on the QPE performance of the radar.

scholarly journals University of Michigan Radiocarbon Dates XII

Radiocarbon ◽  
1968 ◽  
Vol 10 (1) ◽  
pp. 61-114 ◽  
Author(s):  
H. R. Crane ◽  
James B. Griffin
Keyword(s):  
Standard Deviation ◽  
Half Life ◽  
Radiocarbon Dating ◽  
Geiger Counter ◽  
University Of Michigan ◽  
Radiocarbon Dates ◽  
Statistical Errors ◽  
Sources Of Error ◽  
The Many ◽  
Many Sources

The following is a list of dates obtained since the compilation of List XI in December 1965. The method is essentially the same as described in that list. Two CO2-CS2Geiger counter systems were used. Equipment and counting techniques have been described elsewhere (Crane, 1961). Dates and estimates of error in this list follow the practice recommended by the International Radiocarbon Dating Conferences of 1962 and 1965, in that (a) dates are computed on the basis of the Libby half-life, 5570 yr, (b) A.D. 1950 is used as the zero of the age scale, and (c) the errors quoted are the standard deviations obtained from the numbers of counts only. In previous Michigan date lists up to and including VII, we have quoted errors at least twice as great as the statistical errors of counting, to take account of other errors in the over-all process. If the reader wishes to obtain a standard deviation figure which will allow ample room for the many sources of error in the dating process, we suggest doubling the figures that are given in this list.We wish to acknowledge the help of Patricia Dahlstrom in preparing chemical samples and David M. Griffin and Linda B. Halsey in preparing the descriptions.

XIV. The Bakerian Lecture.—inquiries concerning the elementary laws of elec­tricity.—third series

1839 ◽  
Vol 129 ◽  
pp. 215-241 ◽  
Keyword(s):  
Royal Society ◽  
Quantitative Measurement ◽  
Electrical Measurement ◽  
Delicate Balance ◽  
Sources Of Error ◽  
Series Of Experiments ◽  
Many Sources ◽  
Electricity Intensity ◽  
Inductive Power

1. There is no department of science in which the perfection of quantitative measurement, and a clear perception of what we really measure, is more called for than in that of electricity. If we except the valuable researches of Professor Robison and of Coulombe, and the more recent investigations of Dr. Faraday, we can scarcely be said to possess, in common electricity at least, any connected series of experiments carrying with them a rigid numerical value. In the various inquiries into the ele­mentary laws of electricity, which I have had the honour of submitting to the con­sideration of the Royal Society, it has been my endeavour to perfect our methods of electrical measurement, whether relating to the quantity of electricity, intensity, inductive power, or other element requiring an exact numerical value, and, by operating with large statical forces both attractive and repulsive, to avoid many sources of error inseparable from the employment of very small quantities of elec­tricity, such as those affecting the delicate balance used by Coulombe. The instruments resorted to in these further inquiries have been employed with this view; they have been already described; I have only occasion to briefly mention some recent improvements in the hydrostatic electrometer mentioned in my first paper, and represented in Plate III. fig. 1.

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