Showing papers by "Edward Hæggström published in 2007"
TL;DR: Posturographic measurements are repeatable and have a circadian effect, which may be influenced by sleepiness, which was investigated in 30 healthy volunteers.
Abstract: OBJECTIVE: Daytime sleepiness correlates with sleep-related accidents, but convenient tests for occupational sleepiness monitoring are scarce. The effect of daytime on balance, on posturographic measurements, and on their repeatability was investigated in 30 healthy volunteers as part of our work to develop such a test. METHODS: The daytime effect was assessed by measuring balance at 8:30 am, 10:30 am, and 1:30 pm. The repeatability was assessed with morning trials once a week for 1 month. The posturographic test was performed on a static force platform, and the balance was evaluated from a fractal dimension of sway, most common sway amplitude, and time interval for open-loop stance control. RESULTS: The balance worsened during the day, and it was possible to determine whether the measurement was performed in the morning or in the afternoon. The morning balance remained unchanged during the month-long test. CONCLUSIONS: Posturographic measurements are repeatable and have a circadian effect, which may be influenced by sleepiness. Language: en
58 citations
TL;DR: The results show that the ultrasonic method is capable of monitoring the gas-solid structure of the cheese during the ripening process and can be used to detect and to characterize cheese-eyes and cracks in ripened cheese.
36 citations
TL;DR: It is shown, that the time awake in separate trials is posturographically measurable: positive predictive value 69%, sensitivity 56%, and specificity 96%.
Abstract: Although reduced sleep often underlies traffic and occupational accidents, convenient sleepiness testing is lacking. We show that posturographic balance testing addresses this issue, because balance testing predicts hours of wakefulness, which could facilitate sleepiness testing. Here, we equate balance scores from separate trials, blinded to the experimenter, with those recorded as a function of known and increasing time awake (i.e. during sustained wakefulness); we show, that the time awake in separate trials is posturographically measurable: positive predictive value 69%, sensitivity 56%, and specificity 96%. These results encourage further work developing posturographic sleepiness monitoring.
19 citations
26 Dec 2007
TL;DR: In this article, the authors proposed a model to describe the breakage mechanism during tangential US excitation at constant pressure in a wirebonder, based on theoretical estimations and experimental measurements.
Abstract: A few models have earlier been proposed to explain Al oxide breakage during US wirebonding as presented by L. Levine, but no widely accepted theory exists. We propose a model to describe the AlOx breakage mechanism during tangential US excitation at constant pressure in a wirebonder. The model is based on theoretical estimations and experimental measurements. We measure with a laser Doppler vibrometer the relative wire-base displacement and propose that stick-slip and micro-slip behavior is prevalent during ultrasonic bonding. Displacement was measured at rim of the rectangular 14 mum thick and 80 mum width Al wire and at the silicon microchip base. A rectangular shaped wire was used to have probe light good reflection. We combined displacement measurements, detailed SEM analysis of contact interfaces and FEM of the bond structure during the bonding process. We also made a synthesis of the current bonding process knowledge. As a synthesis we propose a two-step model, including early stage scrubbing and later microweld expansion. Validation of the proposed model is discussed. This work and the obtained results are steps towards a fundamental quantitative US bonding theory that is necessary to develop reliable bonding technologies towards finer-pitch and more reliable interconnections.
11 citations
05 Sep 2007
TL;DR: In this paper, a real-time re-programmable digital signal processor is used to combine steering and position detection to create a fast and versatile closed-loop feedback controlled instrument, which can be manipulated by steering the trap beam, while the object position is measured with sub-nanometer resolution.
Abstract: Optically trapped microshperes can be manipulated by steering the trap beam, while the object position is measured with
sub-nanometer resolution. A fast steering system is required to create feedback loop for measurements at a constant force
or to increase position detection precision by trap stiffening. Using a real-time re-programmable digital signal processor,
we combine steering and position detection to create a fast and versatile closed-loop feedback controlled instrument. We
describe the construction and calibration of the instrument. We show that a proportional gain position-clamp algorithm
can achieve about 10-fold increase in effective trap stiffness while higher gains lead to unwanted resonances.
6 citations
TL;DR: It was found that with increasing TA, the posturographic parameters estimated the subjects' TA more accurately, and repeating the analysis using shorter trial lengths showed that 18 s sufficed to achieve the targeted 5 h accuracy.
Abstract: Sleepiness correlates with sleep-related accidents, but convenient tests for sleepiness monitoring are scarce. The posturographic test is a method to assess balance, and this paper describes one phase of the development of a posturographic sleepiness monitoring method. We investigated the relationship between trial length and accuracy of the posturographic time-awake (TA) estimate. Twenty-one healthy adults were kept awake for 32 h and their balance was recorded, 16 times with 30 s trials, as a function of TA. The balance was analysed with regards to fractal dimension, most common sway amplitude and time interval for open-loop stance control. While a 30 s trial allows estimating the TA of individual subjects with better than 5 h accuracy, repeating the analysis using shorter trial lengths showed that 18 s sufficed to achieve the targeted 5 h accuracy. Moreover, it was found that with increasing TA, the posturographic parameters estimated the subjects' TA more accurately.
6 citations
TL;DR: In this paper, a computerized differentiation of two birch types was performed using ultrasound, and a propagation velocity of 4MHz longitudinal tone bursts, transmitted through block samples of 20×20mm2 cross section, comprising of both CB and SB woods, was determined.
Abstract: We report on computerized differentiation of two birch types. Curly birch (CB, Betula pendula var. carelica Sok) commands a higher price than a normal silver birch (SB, Betula pendula Roth). Hence it is crucial to differentiate the two wood types when the trees are young. We studied the possibility to use ultrasound for such differentiation. A propagation velocity of 4MHz longitudinal tone bursts, transmitted through block samples of 20×20mm2 cross section, comprising of both CB and SB woods, was determined. The samples originating from southern Finland were sawed so that the sound propagation direction was longitudinal or radial with respect to the trunk. One sample set comprised of seven different sample thicknesses with a range of 2–12mm. From the time-of-flight measurements of the samples (19±1%weight humidity) the wave propagation velocity under laboratory conditions (50±5%RH, 23±1°C) was determined from a least-squares fit. The results indicate a significant difference (t-test p=0.032 and velocity d...
3 citations
01 Jan 2007
2 citations
28 Mar 2007
TL;DR: In this paper, a study on structural quality control of Swiss-type cheese with ultrasound was presented, which used a longitudinal mode pulse-echo setup using 1-2MHz ultrasonic frequencies to detect cheese eyes and ripening induced cracks.
Abstract: A study on structural quality control of Swiss‐type cheese with ultrasound is presented. We used a longitudinal mode pulse‐echo setup using 1–2MHz ultrasonic frequencies to detect cheese‐eyes and ripening induced cracks. Results show that the ultrasonic method posses good potential to monitor the cheese structure during the ripening process. Preliminary results indicate that maturation stage could be monitored with ultrasonic velocity measurements. Further studies to verify the method’s on‐line potential to detect low‐structural‐quality cheeses are planned.
2 citations
22 Oct 2007
TL;DR: It was found that TA can be estimated with plusmn2.5 h accuracy using 30 s trial length, but for a fast, reliable and convenient sleepiness monitor even better TA estimation accuracy and shorter trial length is needed.
Abstract: A previous posturographic force platform study verified that human balance deteriorates as a function of time awake (TA) [1, 2]. It was found that TA can be estimated with plusmn2.5 h accuracy using 30 s trial length. For a fast, reliable and convenient sleepiness monitor even better TA estimation accuracy and shorter trial length is needed. We continued this quest by modeling the quiet stance test situation with a single-link inverted pendulum model (SLIPM). The center-of-mass (COM) trace in the AP (anterior-posterior) direction was calculated from the measured center-of-pressure (COP) trace. The sway angle thetas, ankle torque tau and the horizontal force F acting on the COM were calculated from the SLIP equations - each analyzed with 13 different sway measures, i.e. variables that correlate with TA. The effect of circadian rhythm was separated from the sway measures. Twenty subjects' sway measures were analyzed. The SLIPM-based posturographic averaged TA estimation accuracy improved to plusmn2.3 h. The trial length could be shortened to 21 s.
2 citations
11 Jan 2007-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: The FinnCRack as discussed by the authors is a tracker outer barrel (TOB) based telescope that measures tracks of cosmic particles using a silicon strip detector-based telescope that can be used for noise and cluster shape studies.
Abstract: We present a cosmic rack, the FinnCRack. This device is a silicon strip detector-based telescope that measures tracks of cosmic particles. The FinnCRack is constructed using components of the Tracker Outer Barrel (TOB) of the CMS experiment at the CERN LHC. The device is part of the TOB integration and verification effort together with its sister telescope, the CERN CRack. Both CRacks mimick a six degree slice of the TOB barrel structure. The FinnCRack is intended to (a) serve as a platform for TOB software development, both analysis and online software such as run control; (b) be used for noise and cluster shape studies; (c) act as a reference tracker in detector studies; and (d) provide a testbed for track-based alignment testing and development. The construction and setup of the FinnCRack have been documented in detail—the entire chain from connecting cables to physics data analysis—and the operation guide was tested in practice. Both these actions serve the purpose of training and attracting future HEP students. We also showed that we were able to measure cosmic muon tracks.
26 Dec 2007
TL;DR: In this article, a 9.5 MHz instrument for quantitative inclusion (manganese-sulphur) and pore characterization in immersed steel billets was developed, which is capable of quantitative foreign body classification.
Abstract: Steel fabrication suffers from inclusions and pores that are formed into steel during production. Ultrasonic characterization of unrolled steel bars is challenging due to low signal-to-noise ratio (SNR). Signal processing provides methods to characterize granular steel samples. We are developing a 9.5 MHz instrument for quantitative inclusion (manganese-sulphur) and pore characterization in immersed steel billets. The instrument is capable of quantitative foreign body classification. MnS inclusions and soft inclusions (pores) can be segregated. After the samples were characterized ultrasonically, inclusions were cut out and a scanning electron microscope (SEM) was used to validate the results. The instrumentation will allow nondestructive waste product content estimation for each waste material separately. It improves the steel fabrication quality control by giving detailed information of the inner structure and therefore allowing more precise fabrication process control.
21 Mar 2007
TL;DR: In this paper, an ultrasonic instrument capable of measuring seismic velocities (Vp and Vs) under crustal temperatures (20 −300°C) and pressures (0 −300 MPa) is built.
Abstract: An ultrasonic instrument capable of measuring seismic velocities (Vp and Vs) under crustal temperatures (20–300°C) and pressures (0–300 MPa) is built. The results obtained with the device will be used to understand recent seismic reflection (FIRE) data from the Outokumpu area in Finland. Collectively, the data will be integrated to construct a new geological model of the Outokumpu formation.
26 Dec 2007
TL;DR: In this article, a standing ultrasonic wave pattern and SAXS X-ray diffraction (CuKalpha 1.54 Aring) were combined to map the local elastic modulus.
Abstract: We continue our quest to determine localized micro- elasticity by combining a standing ultrasonic wave pattern and SAXS X-ray diffraction (CuKalpha 1.54 Aring) to map the local elastic modulus. This was done in 20times20times1.5 mm3 dry Scots pine (Pinus Sylvestris L) soft wood and high-density polyethene (HDPE), acting as homogenized wood phantom samples. An Atmel Atmega 8515 (8 bit, 16 MHz) microprocessor launches and upholds a resonant lambda/2 wave pattern in the radial wood direction using a 100 Hz feedback loop. By varying the transmitted ultrasonic power, it is possible to alter the local stress within the volume probed by the 1 mm2 X-ray beam. The local strain in unit crystals is determined from changes in the width and position of the X-ray diffraction peaks. The results indicate that the method is applicable for localized quantitative elasticity mapping.
01 Jan 2007
TL;DR: In this article, the effect of macroscopic stress on micro scale modulus of elasticity of Scots pine (Pinus Sylvestris L.) wood cell walls was measured using a measurement setup combining x-rays, and ultrasonics.
Abstract: We want to understand where wood strength comes from in order to artificially engineer the mechanical properties of wood. This study aims to measure the effect of macroscopic stress on micro scale modulus of elasticity of Scots pine (Pinus Sylvestris L.) wood cell walls. Our approach allows estimation of local elasticity as a function of stress as well as the stress-strain curve without inducing creep. We propose a measurement setup combining x-rays, and ultrasonics. A piezoceramic transducer launches continuously longitudinal waves in the longitudinal wood direction at a suitable frequency generating a λ/2 resonance into a 20x10x1.5 mm 3 cubic sample. The resonance is maintained by changing the sonic frequency with an Atmega 5815 microprocessor driven feedback loop into which an error signal obtained with a piezoceramic transducer is inserted. The diffraction pattern of the samples was measured after the resonance was achieved using CuKα radiation (1.54 A) with a beam size of 0.3x1.2mm 2 . In this paper, results from both wood and clay-polymer (PP) composites are presented.
28 Mar 2007
TL;DR: In this article, the applicability of an airborne ultrasonic pulse-reflection (UPR) method towards lower porosities was reported. But the authors used ceramic samples to evaluate the feasibility of extending the UPR range into low porosity (<35%).
Abstract: We report on efforts to extend the applicability of an airborne ultrasonic pulse‐reflection (UPR) method towards lower porosities. UPR is a method that has been used successfully to estimate porosity and tortuosity of high porosity foams. UPR measures acoustical reflectivity of a target surface at two or more incidence angles. We used ceramic samples to evaluate the feasibility of extending the UPR range into low porosities (<35%). The validity of UPR estimates depends on pore size distribution and probing frequency as predicted by the theoretical boundary conditions of the used equivalent fluid model under the high‐frequency approximation.
28 Mar 2007
TL;DR: In this paper, the authors verify simulation results indicating that carbon ion irradiation increases the stiffness of single wall carbon nanotube bucky paper (SWCNT), and the results indicated a significant increase both in the shear modulus and in the longitudinal modulus for certain irradiation doses as predicted by simulations.
Abstract: We verify simulation results indicating that carbon ion irradiation increases the stiffness of single wall carbon nanotube bucky paper (SWCNT). 4 MHz longitudinal and 15 MHz shear ultrasonic signals were transmitted by means of dry‐coupled acoustic horns through 40±4 μm thick samples and the time‐of‐flight (TOF) through the samples was measured. From the TOF the velocity of the wave was determined and the out‐of‐plane elastic and shear moduli were calculated. The nonlinearity parameter B/A for the irradiated and reference sample was measured. The results indicated a significant increase both in the shear modulus (90 %) and in the longitudinal modulus (69 %) for certain irradiation doses as predicted by simulations. In addition, a 36% increase in the acoustic nonlinearity parameter (B/A) was observed. The investigated fluence range was 1⋅1013 to 3⋅1014 cm−2.
01 Jan 2007
28 Mar 2007
TL;DR: The mechanical properties of a silicone tube blood vessel phantom (outer radius 404±004 mm and wall thickness 100±002 mm) carrying in-plane ultrasound wave propagation, was studied as function of applied axial tension as discussed by the authors.
Abstract: The mechanical properties of a silicone tube blood vessel phantom (outer radius 404±004 mm and wall thickness 100±002 mm) carrying in‐plane ultrasound wave propagation, was studied as function of applied axial tension A 23 kHz, 1‐cycle square signal was excited into the tube with a piezoceramic pickup and received with an inductive pickup The wave phase velocities in the tube were determined by measuring the time‐of‐flight (TOF) at different inter‐transducer distances The longitudinal mode sound velocity ranged from 83 m/s to 88 m/s, and from 51 m/s to 58 m/s for the shear mode respectively with tensions ranging from 31 to 364 kPa This compares with the FEM estimate A laser‐Doppler vibrometer (LDV) detected an out‐of‐plane mode propagating along the tube An increase in the sound velocity caused by artificially induced lesions was detected
28 Mar 2007
TL;DR: In this paper, the propagation velocity of 4 MHz longitudinal ultrasonic 5-cycle bursts transmitted through block samples with a cross-section of 20×20 mm2 comprising both curly and non-curly birch was determined.
Abstract: Curly birch (CB, Betula pendula var. carelica) commands a 10x higher price than silver birch. For thinning purposes it is crucial to differentiate between the two types as early as possible. We studied the possibility to use ultrasound for this differentiation. The propagation velocity of 4 MHz longitudinal ultrasonic 5‐cycle bursts transmitted through block samples with a cross‐section of 20×20 mm2 comprising both curly and noncurly birch was determined. The samples originated from southern Finland and were sawn in both longitudinal and radial directions. One sample set consisted of several different sample thicknesses ranging from 2 mm to 12 mm. From time‐of‐flight measurements (TOF) through the samples the wave velocity under laboratory conditions (RH = 50%, T = 23 C) was determined from a least‐squares‐fit. The results indicate a significant difference (t‐test 3.2%, velocity difference 24%) in longitudinal direction and a highly significant difference (t‐test 0.1%, velocity difference 22%) in the radial direction. A probability of detection (POD) test was conducted using a larger number of samples originating from both different trunks and from one single trunk from curly and noncurly sections. The results indicate that ultrasound might be useful for differentiation of curly and noncurly birch in young standing specimens.
26 Dec 2007
TL;DR: In this article, a phased array solution has been implemented to allow fast measurements, dynamic focusing and to alleviate shadowing problems for structural quality analysis of Swiss-cheese, and the results show the potential of the method.
Abstract: We develop an ultrasonic method for nondestructive structural quality analysis of Swiss-cheese. A phased array solution has been implemented to allow fast measurements, dynamic focusing and to alleviate shadowing problems. Initial results exploiting this setup are presented. The results show the potential of the method. However, high attenuation causes frequency downshift, which decreases the resolution as a function of probing depth. Structural inhomogeneity decreases the SNR of acquired signals. These issues lead to a high dynamic range demand for the system. Sophisticated imaging methods should be utilized to fully exploit the beam focusing and deflection capabilities of phased arrays, while maintaining rapid measurements. Compared to our earlier work with single transducer setup, a ten times decrease in measurement time was obtained.
01 Jan 2007
TL;DR: In this article, a combined ultrasound and resistance measurement was conducted in situ during irradiation of single wall carbon nanotube (SWCNT) mats, and the results showed that the measurement setup is ready for in situ experiments and that it produces reliable results.
Abstract: We present preliminary results from a combined ultrasound and resistance measurement to be conducted in situ during irradiation of single wall carbon nanotube (SWCNT) mats. We focused on whether it is possible to improve the mechanical properties of the SWCNT paper samples by means of C ion irradiation. Simulation work indicated that such engineering could be possible, and our earlier ex post results have shown that it is possible to modify the elastic moduli. We present results obtained with a setup for combined z-directionultrasound and conductivity probing which agree with those published earlier. In addition, we present stability test results obtained with the developed in-plane ultrasonic transducers combined with the electrical conductivity test. Our results show, that the measurement setup is ready for in situ experiments and that it produces reliable results.