Lohne, Kjetil Daae

Environmental Observations

CMR contribute to observe our environment through research, technology and product development. We work for effective environmental monitoring in real-time.

Investigating the Polar Regions

Reliable technologies for long term operation in extreme environments

ICEX - Automatic weather station

CMR delivers automatic observation stations that can be deployed on the ice for environmental and ice drift monitoring.

Bathymetry Buoy

The Bathymetry Bouy is designed for water depth measurement and satellite data communication of data in harsh arctic environments.

ES300 - Upward Looking Sonar

The ES300 instrument is an upward looking sonar used in the arctic/antarctic for measuring ice thickness. It has an battery lifetime of 1-5 years. The first versions were made in 1989 continuously developed since.

Seisdrift

An autonomous drifting seismic buoy for acquisition of single channel seismic reflection data from drifting sea ice in the Arctic Ocean and real-time data transmission to shore via Iridium

Beam Diffraction Effects in the Backward Wave Regions of Viscoelastic Leaky Lamb Modes for Plate Transmission at Normal Incidence

Aanes, Magne; Lohne, Kjetil Daae; Lunde, Per; Magne Vestrheim

Dispersion properties of Lamb and leaky Lamb modes in elastic and viscoelastic plates

Aanes, Magne; Lohne, Kjetil Daae; Lunde, Per; Vestrheim, Magne

Finite aperture effects in the backward wave propagation region of a leaky Lamb mode at normal beam incidence

Lohne, Kjetil Daae; Lunde, Per; Aanes, Magne, Vestrheim, Magne

Time-of-flight dependency on transducer separation distance in a reflective-path guided-wave ultrasonic flow meter at zero flow conditions

Aanes, Magne; Frøysa, Kjell-Eivind; Kippersund, Remi Andre; Lohne, Kjetil Daae; Lunde, Per;

http://dx.doi.org/10.1121/1.4996851

Beam diffraction effects in sound transmission of a fluid-embedded viscoelastic plate at normal incidence

Aanes, Magne; Lohne, Kjetil Daae; Lunde, Per; Vestrheim, Magne

Finite aperture influence on energy concentration, frequency shift, and signal enhancement, for acoustic transmission in the negative group velocity region of the S1 leaky Lamb mode

Aanes, Magne; Lohne, Kjetil Daae; Lunde, Per; Vestrheim, Magne

Transducer finite aperture effects in sound transmission near leaky Lamb modes in elastic plates at normal incidence

Aanes, Magne; Lohne, Kjetil Daae; Lunde, Per; Vestrheim, Magne

The interaction of ultrasonic waves with fluid-embedded viscoelastic plates, pipes, and shells, have been subject to extensive theoretical and experimental studies over several decades. In normal-incidence through-transmission measurements of a water-embedded solid plate using ultrasonic piezoelectric transducer sound fields, significant deviations from plane wave theory have recently been observed.

Beam transmission of water-embedded steel plate at normal incidence. Diffraction effects in the S1 to A3 region

Aanes, Magne; Lohne, Kjetil Daae; Lunde, Per; Vestrheim, Magne;

Measurement of the sound transmission through a fluid­?embedded viscoelastic plate at normal incidence can show significant deviations to the plane­?wave theory, experiencing both frequency shift and signal level variation in relation to the plane­?wave theory.

Transducer beam diffraction effects in sound transmission near leaky Lamb modes in elastic plates at normal incidence

Aanes, Magne; Lohne, Kjetil Daae; Lunde, Per; Vestrheim, Magne;

The plane wave theory of fluid-embedded viscoelastic plates is often used in waveguide applications, and to estimate wall thickness and sound velocities in plates and pipe walls. In normal-incidence through-transmission measurements, downward frequency shift, signal amplification, and distorted beam patterns, as compared to plane-wave theory, have been observed  for resonant peaks in frequency bands near certain Lamb modes.

Normal incident ultrasonic beam transmission through a water-immersed plate using a piezoelectric transducer. Finite element modelling, angular spectrum method and measurement

Aanes, Magne; Lohne, Kjetil Daae; Lunde, Per; Vestrheim, Magne;

Accurate time of flight (TOF) measurements in non-invasive ultrasonic applications for media contained by plane walls or pipes, demand a precise understanding and control of the generation, transmission and reception of sound beams through solid layers (plane walls or pipes) and the surrounding fluids.

Ultrasonic beam transmission through a water-immersed plate at oblique incidence using a piezoelectric source transducer. Finite element - angular spectrum modeling and measurements

Aanes, Magne; Lohne, Kjetil Daae; Lunde, Per; Vestrheim, Magne;

A measurement system consisting of a piezoelectric transducer and a water-immersed steel plate is studied.

Finite element analysis of acoustic beam interactions with plate at normal incidence. Comparison with a 3D angular spectrum method and measurements

Aanes, Magne; Lohne, Kjetil Daae; Lunde, Per; Vestrheim, Magne;

The use of the finite element method (FEM) for studying the interactions of an acoustic beam with an elastic steel plate is discussed, in comparison with a 3D angular spectrum method (ASM) and measurements.

Measurements and 3D simulation of ultrasonic directive beam transmission through a water-immersed steel plate

Lohne, Kjetil Daae; Lunde, Per; Vestrheim, Magne;

A 3D full-wave angular spectrum simulation model for reflection and transmission of ultrasonic directive circular piston sound fields, from and through a fluid-immersed isotropic solid plate has been implemented.

Ultrasonic signal transmission in plates – Study of a steel plate immersed in water

Lohne, Kjetil Daae; Lunde, Per; Magne Vestrheim

In the present work, a theory for the description of the propagation of plane ultrasonic waves through a fluid loaded plate is described. The theory assumes different fluid loading at the two interfaces, but the special case with the same fluid loading is also treated.