Search for dissertations about: "Attenuation measurement"

Showing result 1 - 5 of 73 swedish dissertations containing the words Attenuation measurement.

2. 1. Acoustical properties of earplugs

   Author : Per Hiselius; Teknisk akustik; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Maskinteknik; hydraulik; vakuumteknik; vibrationer; akustik; vibration and acoustic engineering; vacuum technology; hydraulics; Mechanical engineering; acoustic modelling; objective measurement; insertion loss; earplugs; HPE; HPD; hearing protectors; Two-Port; Four-Pole; attenuation; electro acoustics; acoustics;

   Abstract : In this study an experimental setup for measurements of high impedance objects in ducts, yielding the acoustical Two-Port properties of the object, is applied to earplugs. A frequently used experimental setup for measuring objective acoustical properties of earplugs is that of artificial ears. Great effort is spent on duplicating the human ear. READ MORE

4. 2. Attenuation correction in pulmonary and myocardial single photon emission computed tomography

   Author : Helén Almquist; Lund Klinisk fysiologi; []
   Keywords : MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Klinisk fysiologi; tomography; medical instrumentation; radiology; Clinical physics; downscatter; myocardial perfustion; ventilation-perfusion ratio; radiologi; pulmonary density; pulmonary perfusion; attenuation correction; SPECT; transmission measurement; tomografi; medicinsk instrumentering;

   Abstract : The objective was to develop and validate methods for single photon emission computed tomography, SPECT, allowing quantitative physiological and diagnostic studies of lung and heart. A method for correction of variable attenuation in SPECT, based on transmission measurements before administration of an isotope to the subject, was developed and evaluated. READ MORE

5. 3. Time and Frequency Domain Measurement Methods for High Frequency Characterisation of Power Cables

   Author : Ruslan Papazyan; KTH; []
   Keywords : Attenuation measurement; XLPE insulation; Power cables;

   Abstract : Time Domain Reflectometry (TDR) has been used forlocalisation of transmission line discontinuities in variousapplications. One of the challenges when applying TDR on powercables is to obtain knowledge of the high frequencycharacteristics of both the degraded and the undegradedsections of the cable. READ MORE

6. 4. Interception evaporation : processes and measurement techniques

   Author : Angela Lundberg; Luleå tekniska universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Applied Geology; Tillämpad geologi;

   Abstract : In temperate regions, evaporation of water intercepted by the vegetation represents an important part of the evapotranspiration. A review of interception evaporation studies showed that knowledge about interception evaporation processes is limited and progress is hampered by technical difficulties. READ MORE

7. 5. Determining the quality of natural gas and biomethane : Development of a correlative method and instrument prototype for measuring gas quality

   Author : Taras Koturbash; Vladimir G. Kutcherov; Andrew R. Martin; Khaled Loubar; KTH; []
   Keywords : Natural gas; biomethane; calorific value; Wobbe Index; ultrasonic measurement; sound attenuation; Energy Technology; Energiteknik;

   Abstract : The composition of natural gas highly depends on its origin: natural gas from various deposits, substitute natural gas that can be produced from fossil fuels or renewable sources. The intermixing of gases from various supply sources during pipeline transportation also leads to more complicated and unpredictable gas composition variations at the consumption site. READ MORE