Spelling suggestions: "subject:"founding"" "subject:"abounding""
31 |
Akustiks jb-sondering : En jämförelse mellan mätning på jord och asfalt / Acoustic Soil-Rock Sounding : A comparison between measurements on soil and asphaltPöder, Sofie, Tranblom, Sofie January 2020 (has links)
Soil-Rock sounding (jb-sounding) is a common method in Sweden, used to determine soil layering. An extension of this method, referred to as Acoustic Soil-Rock sounding, is currently under developement at KTH in Stockholm. This method uses the ground vibrations induced by drilling during jb-sounding. The aim is to investigate if additional information on the soil can be obtained by analysis of the vibrations, e.g. thin layers that cannot be registered by conventional jb-sounding.In this Master’s thesis, a further study of the method Acoustic Soil-Rock sounding has been undertaken to see whether the method is applicable or not. Furthemore, it is investigated whether it is possible to perform the vibration measurements on asphalt covered ground and obtain reliable results, alternatively whether it is possible to detect some systematic difference. This has been conducted as a field observation where the data has been collected during jb-sounding. The data, i.e. the vibration signal, was registered using geophones, one placed on asphalt and one on soil. Measurements from nine boreholes were performed in total; however, only eight of these have been analysed due to failing to register the depth signal properly in one case. The vibration signals have been processed using MATLAB to obtain the frequency spectra and spectrograms, to which the results of the jb-sounding and previous acoustic measurements have been compared.After analysis and comparison of the results, the conclusion was that Acoustic jb-sounding is an applicable method that ought to be developed further and the results from the measurements performed on asphalt were reliable. That is to say, no discernible difference could be deduced between measurements conducted on asphalt and soil. / Jord-bergsondering (jb-sondering) är en i Sverige vanlig metod för att undersöka jordens uppbyggnad. En påbyggnad av denna metod, kallad akustisk jb-sondering, håller för tillfället på att studeras vid KTH i Stockholm. Denna metod går ut på att mäta de vibrationer som uppstår vid markytan till följd av borrning, i samband med jb-sondering. Syftet är att undersöka huruvida kompletterande information från jordlager kan erhållas genom analys av vibrationerna, såsom tunnare lager som annars inte kan registreras av den konventionella jb-sonderingen.I det här masterarbetet har ytterligare undersökning om metoden akustisk jb-sondering genomförts för att först se huruvida metoden är applicerbar eller inte. Vidare studeras om det är möjligt att utföra mätningar även på asfalt och då erhålla tillförlitliga resultat, alternativt om det är möjligt att utläsa någon systematisk skillnad. Detta har genomförts som en fältstudie där data har samlats in i samband med jb-sonderingar. Vibrationssignalerna registrerades med geofoner placerade på jord samt asfalt. Totalt genomfördes mätningar vid 9 stycken borrhål, men endast 8 av dessa har analyserats då djupsignalen från ett borrhål inte registrerades. Vibrationssignalerna har sedan bearbetats i MATLAB för att ta fram frekvensspektrum och spektrogram som sedan har jämförts med resultat från jb-sonderingar samt tidigare studier.Efter analys och jämförelse av resultaten drogs slutsatsen att akustisk jb-sondering är en applicerbar metod som bör utvecklas vidare och att resultaten från mätningar utförda på asfalt var tillförlitliga. Det vill säga ingen större skillnad mellan mätningarna på jord respektive asfalt kan ses.
|
32 |
DYNAMIC BEHAVIOR OF MULTIPATH INTERFERENCE IN ARTM CHANNEL SOUNDING DATADavis, Adam Todd 10 1900 (has links)
International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / Data collected during July 1999 at Edwards EAFB by the Advanced Range Telemetry (ARTM) program
is examined to characterize the dynamic behavior of multipath interference in an aeronautical telemetry
channel. Multipath fade events are analyzed in the frequency domain to show how these fades appear,
evolve, and disappear from the channel. A channel model and examples from the channel sounding data
are used to show the dynamic nature of these fade events. The Doppler power spectrum is used to
quantify the exact time-varying nature of the multipath fade events. The coherence time, or the amount
of time the channel can be viewed as unchanging, is obtained from the Doppler power spectrum and is
calculated to be 100 ms in the data sets examined in this paper. This implies that adaptive multipath
mitigation techniques must have an adaptation bandwidth of 10 Hz.
|
33 |
Comparing Remote Sounding Measurements of a Variable StratosphereToohey, Matthew 23 February 2010 (has links)
The measurement of trace gases through remote sounding techniques has led to a better understanding of the processes controlling the structure and variability of the stratosphere. Differences between measurements over space and time are due to atmospheric variability and instrument errors: thus, comparison of measurements can be used to test our knowledge of both.
Comparisons of measurements over long time periods are used to identify trends. Balloon-borne infrared emission radiometer instruments have been used to make measurements of midlatitude stratospheric HNO3 spanning a period of twelve years. The timing of the measurements is notable, since they occur before and well after the eruption of Mt. Pinatubo, which significantly perturbed HNO3 levels, complicating prior trend analyses. No significant differences are found between the HNO3 retrievals, although large measurement uncertainties preclude any conclusion concerning trends.
Comparisons of measurements that are closely spaced in space and time are useful for satellite validation, where one aims to reduce the effect of atmospheric variability on the estimation of systematic and random errors. A novel technique for the estimation of systematic error, which differentiates between additive and multiplicative bias, is introduced. In a comparison of measurements by the ACE-FTS and Aura MLS instruments, significant multiplicative biases are identified and described.
In order to validate the reported random errors (RREs) of measurements, satellite validation studies often focus on measurements in the tropical stratosphere, where variability is weak. The scatter in tropical measurements can then be used as an upper limit on instrument precision. In an analysis of tropical measurements by the ACE-FTS, scatter is found to be roughly consistent with the RREs for H2O and CO. The scatter in measurements of O3, HNO3, and N2O, while larger than the reported random errors, is roughly consistent with the variability simulated in the Canadian Middle Atmosphere Model. This work implies that the random error of the ACE-FTS measurements is smaller than the weak natural variability of the tropical stratosphere.
|
34 |
Comparing Remote Sounding Measurements of a Variable StratosphereToohey, Matthew 23 February 2010 (has links)
The measurement of trace gases through remote sounding techniques has led to a better understanding of the processes controlling the structure and variability of the stratosphere. Differences between measurements over space and time are due to atmospheric variability and instrument errors: thus, comparison of measurements can be used to test our knowledge of both.
Comparisons of measurements over long time periods are used to identify trends. Balloon-borne infrared emission radiometer instruments have been used to make measurements of midlatitude stratospheric HNO3 spanning a period of twelve years. The timing of the measurements is notable, since they occur before and well after the eruption of Mt. Pinatubo, which significantly perturbed HNO3 levels, complicating prior trend analyses. No significant differences are found between the HNO3 retrievals, although large measurement uncertainties preclude any conclusion concerning trends.
Comparisons of measurements that are closely spaced in space and time are useful for satellite validation, where one aims to reduce the effect of atmospheric variability on the estimation of systematic and random errors. A novel technique for the estimation of systematic error, which differentiates between additive and multiplicative bias, is introduced. In a comparison of measurements by the ACE-FTS and Aura MLS instruments, significant multiplicative biases are identified and described.
In order to validate the reported random errors (RREs) of measurements, satellite validation studies often focus on measurements in the tropical stratosphere, where variability is weak. The scatter in tropical measurements can then be used as an upper limit on instrument precision. In an analysis of tropical measurements by the ACE-FTS, scatter is found to be roughly consistent with the RREs for H2O and CO. The scatter in measurements of O3, HNO3, and N2O, while larger than the reported random errors, is roughly consistent with the variability simulated in the Canadian Middle Atmosphere Model. This work implies that the random error of the ACE-FTS measurements is smaller than the weak natural variability of the tropical stratosphere.
|
35 |
A Sliding Correlator Channel Sounder for Ultra-Wideband MeasurementsPirkl, Ryan Jesse 29 June 2007 (has links)
This body of work forms a detailed and comprehensive guide for those interested in performing broadband wireless channel measurements. Discussion addresses the theoretical and practical aspects of designing and implementing a sliding correlator channel sounder, as well as how such a system may be used to measure and model the ultra-wideband wireless channel. The specific contributions of this work are as follows:
Developed a systematic methodology for designing optimal sliding correlator-based channel sounders.
Constructed a UWB channel sounder based upon a 17-bit LFSR that attained 1.66 ns of temporal resolution and 34 dB of dynamic range.
Performed an exemplary measurement campaign of the UWB channel from which UWB angular spreads and RMS delay spreads are reported.
The design procedure developed in Chapter 3 will allow researchers to build optimal channel sounders for investigating next-generation wireless channels. Chapter 4 s discussion addresses the real-world challenges of constructing a high performance sliding correlator channel sounder. Finally, the measurement campaign discussed in Chapter 5 outlines a procedure for investigating the spatio-temporal characteristics of the wireless channel and provides some of the first examples of UWB angular spread measurements.
|
36 |
The Sounding Investigation and Resolution of the Air Pollution of Petrochemical Industrial AreaPan, Jia-ming 03 July 2006 (has links)
Over the past 2001~2005 years, the ozone concentration of Kaohsiung county had a rising trend year by year. It¡¦s one of the main reasons that air quality was bad in Kaohsiung and Pingtung Counties. In order to reach the purpose to improve the ozone and air quality effectively, we need to make the whole investigation and of the ozone precursors VOCs and NOx. In addition, the ozone concentration is also influenced by factors, such as intensity of sunshine, temperature, humidity, rainfall, and speed of wind direction, etc. This research mainly investigated the distributing of the ozone precursors of the vertical height and the photochemical ozone formation reactivity with sounding for the 22nd ¡Vthe 25th of November in the Lin-Yuan petrochemical industrial park to discuss the relation of synoptic systems and meteorological parameterization, as the reference used in controlling ozone concentration.
It is known the comprehensive synoptic systems are Northeasterly Monsoon Winds type by the analysis of the meteorological parameterization. The station of fishers association was the downwind position and the station of sin-yuan elementary school was the upwind position. The sea-land breeze, that is normally low-latitude (under about 700 meters) regional wind or local circulation, causes the position change of upper and lower wind. The whole trend of ozone and speed of wind of the two stations had negative correlation obviously and the correlation was bad for the height under 500 meters. The whole trend of ozone and NMHC was negative correlation in range of 100m to 300m that was better than above 500 meters. The whole trend of ozone and NOx was negative correlation in the height of 100 meters and had no correlation in above 300 meters. It shows that correlation of O3 and NOx is relatived to source of NOx pollution and is decreased with the altitude height.
|
37 |
The Effects of Turbulence in an Absorbing Atmosphere on the Propagation of Microwave Signals Used in an Active Sounding SystemOtarola, Angel Custodio January 2008 (has links)
Proper and precise interpretation of radio occultation soundings of planetary atmospheres requires understanding the signal amplitude and phase variations caused by random perturbations in the complex index of refraction caused by atmospheric turbulence. This research focuses on understanding the turbulence and its impact on these soundings.From aircraft temperature, pressure and humidity measurements we obtained a parametric model for estimating the strength of the atmospheric turbulence in the troposphere. We used high-resolution balloon measurements to understand the spatial spectrum of turbulence in the vertical dimension.We also review and extend electromagnetic scintillation theory to include a complex index of refraction of the propagating medium. In contrast to when the fluctuations in only the real component of the index of refraction are considered, this work quantifies how atmospheric turbulent eddies contribute to the signal amplitude and phase fluctuations and the amplitude frequency correlation function when the index of refraction is complex. The generalized expressions developed for determining the signal's amplitude and phase fluctuations can be solved for planar, spherical or beam electromagnetic wave propagation.We then apply our mathematical model to the case of a plane wave propagating through a homogenous turbulence medium and estimate the amplitude variance for signals at various frequencies near the 22 GHz and 183 GHz water vapor absorption features. The theoretical results predict the impact of random fluctuations in the absorption coefficient along the signal propagation path on the signal's amplitude fluctuations. These results indicate that amplitude fluctuations arising from perturbations of the absorption field can be comparable to those when the medium has a purely real index of refraction. This clearly indicates that the differential optical depth approach devised by Kursinski et al. (2002) to ratio out the effects of turbulence on signals passing through a medium of a purely real index of refraction must be modified to include the effects of turbulent variations in the imaginary part of the refractivity.
|
38 |
Acoustic phase measurements from volume scatter in the oceanHuston, Robert Delmar 12 November 2014 (has links)
A primary goal of this thesis has been to demonstrate that stable, useful
measurements of the orientation of the acoustic signal vector as a function of
range and time can be obtained from ocean backscatter, and that this orientation,
or acoustic phase, can be related to the local sound speed distribution.
Such a measurement is quite distinct from the related problem of detecting the
rate of phase change, which forms the basis of Doppler technology. Doppler
measurements can be made using echoes from a single point, or a sparsely
distributed set of targets. Consistent and useful measurement of absolute phase,
is inherently more difficult, since it depends upon the positions of individual scatterers, which are normally random and sparse relative to the acoustic
wavelength. / Graduate
|
39 |
Echo sounder and sonar studies of the diel and seasonal movements of pelagic lake fishesHergenrader, Gary L. January 1967 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1967. / Typescript. Vita. "Diel activity and vertical distribution of yellow perch ... under the ice," by Gary L. Hergenrader and Arthur D. Hasler inserted between leaves 15 and 16. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.
|
40 |
Classification of fish schools from acoustic survey data /Hammond, Tim R., January 2000 (has links)
Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references.
|
Page generated in 0.0665 seconds