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- Eklund, Johan, et al.
(författare)
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Inflicted Damages related to Folding Procedures on Digital Prints
- 2002
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- A study has been performed with the purpose of analysing different folding techniques and its functionality in a climate optimised for digital printing. Coated papers of stock weight 160g/m2, developed for digital printing, were printed in a multifunctional copier and folded with different methods. Results show that using a creasing rule substantially improves the quality. Other factors like folding method, time from print to fold, fibre orientation and toner layer presented small variations regarding fold print quality. The performed study is the start-up of a systematic mapping of folding of digital prints. Future studies will include a wide range of papers, printers, digital presses and finishing equipment. The tests will mainly be performed in a climate- controlled laboratory, giving possibility to analyse folding performance in different air humidity. The aim is to provide new knowledge about finishing of digital prints, as well as solutions to existing problems.
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| 2. |
- Barclay, Susan A, et al.
(författare)
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The shape of the proximal isovelocity surface area varies with regurgitant orifice size and distance from orifice : computer simulation and model experiments with color M-mode technique.
- 1993
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Ingår i: Journal of the American Society of Echocardiography. - 0894-7317 .- 1097-6795. ; 6:4, s. 433-445
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Tidskriftsartikel (refereegranskat)abstract
- The hemispheric proximal isovelocity surface area method for quantification of mitral regurgitant flow (i.e., Qc = 2 pi r2v), where 2 pi r2 is the surface area and v is the velocity at radius r, was investigated as distance from the orifice was increased. Computer simulations and steady flow model experiments were performed for orifices of 4, 6, and 8 mm. Flow rates derived from the centerline velocity and hemispheric assumption were compared with true flow rates. Proximal isovelocity surface area shape varied as distance from each orifice was increased and could only be approximated from the hemispheric equation when a certain distance was exceeded: > 7, > 10, and > 12 mm for the 4, 6, and 8 mm orifices, respectively. Prediction of relative error showed that the best radial zone at which to make measurements was 5 to 9, 6 to 14 and 7 to 17 mm for the 4, 6, and 8 mm orifices, respectively. Although effects of a nonhemispheric shape could be compensated for by use of a correction factor, a radius of 8 to 9 mm can be recommended without the use of a correction factor over all orifices studied if a deviation in calculated as compared with true flow of 15% is considered acceptable. These measurements therefore have implications for the technique in clinical practice.
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| 9. |
- Eidenvall, Lars E. J., 1965-
(författare)
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Cardiovascular modelling and ultrasound heart flow quantification : aortic flow and mitral regurgitation
- 1993
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The primary objective of this thesis was to model and simulate aortic flow and mitral regurgitation and to improve quantitative ultrasound measurements. The tools used were; theoretical analysis, computer simulation, model experiments, image analysis and clinical evaluation.The flow in the aorta is known to be influenced by both cardiac function and vascular characteristics. The influence of vascular characteristics were investigated in a three parameter windkessel model. Peak aortic velocity and acceleration were studied when these parameters were changed. The results indicate that aortic peak flow velocity is related to the compliance of the arterial system while the peak flow acceleration is inversely related to the characteristic impedance of the aorta and large vessels.To obtain a correct aortic flow velocity profile from a two dimensional colour flow echocardiographic investigation, a unit which incrementally delayed the ECG signal was designed and used to control the ultrasound scanning. By combining velocity data from incrementally delayed images in a software program, a time corrected profile was obtained.In order to determine regurgitant heart valve flow volume, the intensity of the ultrasound continuous wave signal has been suggested as a potential method. Measurements in a hydraulic model showed, however, that the intensity of the signal was, in addition to volume, also related to peak velocity, measuring angle and machine settings. Hence, conclusions drawn about regurgitant grade from the intensity signal require caution.Another method for determination of valve regurgitation is to study the laminar and nondisturbed flow in the region of acceleration proximal to the valve, normally the distance from orifice to the first aliased velocity. This was tested first in a steady flow model using colour M mode and colour 2D information, and later in a pulsatile flow model. Four different methods using velocity data from the entire reconstructed 2D velocity vector field were investigated. Model experiments and error calculation showed that flow was best determined by integrating velocities along hemi-spherical lines in two perpendicular planes within an angle of ±45° from the orifice centre line at a distance of approximately 1.2 to 1.4 times the orifice diameter, corresponding to velocities between 0.15 and 0.45 m/s. By combining 2D flow and spectral velocity data, regurgitant volume could be estimated for both circular, diagonal and crescent orifices to within + 15 to -11% from true volume.
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| 12. |
- Eidenvall, Lars, et al.
(författare)
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Two-dimensional color Doppler flow velocity profiles can be time corrected with an external ECG-delay device.
- 1992
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Ingår i: Journal of the American Society of Echocardiography. - 0894-7317 .- 1097-6795. ; 5:4, s. 405-413
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Tidskriftsartikel (refereegranskat)abstract
- Although two-dimensional ultrasound color flow imaging is often considered to be a real-time technique, the acquisition time for two-dimensional color images may be up to 200 msec. Time correction is therefore necessary to obtain correct flow velocity profiles. We have developed a time-correction method in which a specially designed unit detects the QRS complex from the patient and creates a trig pulse that is delayed incrementally in relation to the QRS complex. This trig pulse controls the acquisition of the ultrasound images. A number of consecutively delayed images, with known incremental delay between the sweeps, can thus be stored in the memory of the echocardiograph and transferred digitally to a computer. The time-corrected flow velocity profile is obtained by interpolation of data from the time-delayed profiles. The system was evaluated in a Doppler string phantom test. With this technique it is possible to study time-corrected flow velocity profiles without the need to alter existing ultrasound Doppler equipment.
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| 13. |
- Norberg, Ole, et al.
(författare)
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A comparison of print quality between digital and traditional technologies
- 2001
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Ingår i: IS&T’S INTERNATIONAL CONFERENCE ON DIGITAL PRODUCTION PRINTING AND INDUSTRIAL APPLICATIONS. - Springfield : SOCIETY IMAGING SCIENCE TECHNOLOGY. - 089208233X ; , s. 380-385
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The digital print technologies are advancing both in quality and market share. Today, the print quality of digital printed material has improved and is considered to bee good enough for most purposes. However, the great advantages of digital printing are short runs and variable data printing. In this investigation the print quality of different digital printing technologies, today present on the market, are compared with the quality of traditional technologies such as offset and flexography. A wide range of digital presses, from large production presses to smaller devices for office use, was tested. The substrates used, were all chosen to fit the specific printing technology. The print quality was evaluated by subjective evaluation as well as by technical measurements. To make the comparison of prints from different presses meaningful, color management has been an essential part of the process. An ICC-profile was created for each combination of substrate and press. The results indicate that the offset print quality on fully coated paper is still ahead of what is possible to achieve with digital printing techniques today. This study shows that disturbance, like mottling and gloss variation, are the main shortcomings of the digital printing technologies. Another result, shown in this study, is the fact that digital printing is less sensitive to type of substrate.
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