Studybay is a freelance platform. You get to choose an expert you'd like to work with. Unlike with other companies, you'll be working directly with your writer Phd Thesis Ultrasonic Studies without agents or intermediaries, which results in lower prices Master thesis and projects - Ultrasound technology - Studies - Department of Circulation and Medical Imaging. (NDT), process monitoring, and condition monitoring ultrasound is an important method. for many cases ultrasonic SURF Imaging Topics SURF Imaging Topics SURF Imaging is a new method for ultrasound imaging under development at the Phd Thesis Ultrasonic Studies you do. I am planning to work with your essay writing company in the future. I do Phd Thesis Ultrasonic Studies recommend this website to everyone who wants to receive perfect papers
Ultrasonic Studies of Foods Containing Air - White Rose eTheses Online
To browse Academia. edu and the wider internet faster and more securely, please take a few phd thesis ultrasonic studies to upgrade your browser. Skip to main content. edu no longer supports Internet Explorer. Log In Sign Up. Download Free PDF. Towards a Measurement of Paper Pulp Quality: Ultrasonic Spectroscopy of Fibre Suspensions. Yvonne Aitomäki. Download PDF. Download Full PDF Package This paper. A short summary of this paper. READ PAPER. One of the ways of doing this is to introduce sensors that will provide valuable online phd thesis ultrasonic studies on the characteristics of the pulp so that adjustments can be made to optimise the manufacturing process, phd thesis ultrasonic studies.
The measurement method proposed in this thesis is based on ultrasound, since it is rapid, inexpensive, non- destructive and non-intrusive. Thus could be done online. Since ultrasound propagation and attenuation depends on the material properties through which is propagates, it has the potential to provide measurements of material properties such as pulp fibre density and elasticity.
The aim of this thesis is to investigate the possibility of using ultrasound to measure pulp fibre material properties.
The idea is to solve the inverse problem of estimating these properties from attenuation measurements and to establish the degree of accuracy to which this can be done. Firstly a model is developed and is tested with synthetic fibres to establish is validity. It is then used to solve the inverse problem of estimating mate- rial properties from attenuation measurements, again with synthetic phd thesis ultrasonic studies, to test the accuracy to which these properties can be estimated, phd thesis ultrasonic studies.
Resonance peaks in the frequency response of the attenuation were found. On closer investigation it was established that the location of these peaks in the frequency domain is sensitive to the diameter of the fibres and their material properties.
If the diameter is known, these peaks improve the accuracy of the estimation process. Phd thesis ultrasonic studies the model or the estimation procedure may lead to better results. For the method as it is to have application in the paper and pulp industry there are certain conditions that need to be fulfilled.
These are that we find peaks in the frequency response of the attenuation in pulp, know the diameter distribution of the fibres and the hollow nature of the fibres does not significantly alter the results. We can then, phd thesis ultrasonic studies, potentially, be able to establish the shear modulus of the pulp fibres. If the shear modulus is a factor in paper quality, we may be close to an online measurement of paper pulp quality using ultrasonic spectroscopy.
Improving the model may allow us to estimate further properties and take into account the fibres being hollow, phd thesis ultrasonic studies. The thesis consists of two parts.
The first part includes an overview of the pulp and paper industry and current testing methods, background theory on which the model is based and an overview of the model that is used in predicting ultrasound attenuation. Finally we discuss what needs to be done to take this further, phd thesis ultrasonic studies. The second part contains a collection of four papers describing the research.
vii Contents Chapter 1 — Introduction 1 Chapter 2 — Paper and Pulp Industry 3 2. I would also like to thank Jerker Delsing for reminding me of the big picture. I would especially like to thank Kristina Berglund, who has shown amazing flare at correcting my English and has patiently gone through version after version of this thesis and most importantly come up with the elastic band analogy. Appreciation also goes the Forskningskola för Kvinnor, for giving me the confidence to forge ahead and for the laughing therapy.
Finally my special thanks goes to my husband, Erik, without whose support I could not have done this. And my Mum and Dad for the proof-reading and phd thesis ultrasonic studies. With an annual turnover of EUR 74 billion, the pulp and paper industry is a vital part of the European paper and forest economic cluster[1]. For the paper and pulp industry phd thesis ultrasonic studies Sweden and Finland to remain competitive against countries with lower overheads, they have to constantly strive to improve the quality and the efficiency of the manufacturing process.
The high cost of energy in Europe make improvements in energy efficiency a considerable cost saving. The balance is then to reduce the energy consumption whilst maintaining quality. Hence the need for improving process control. A large number of instruments exist for measuring different aspects of pulp, such as the brightness, chemical analysis, phd thesis ultrasonic studies, consistency and fibre properties [2]. With the increase in computer processing power, rapid image analysis has allowed optical measurement techniques to become standard practice in the paper and pulp manufacturing process in Scandinavia.
Examples of devices that use optical-based image analysis are the STFI Fibremaster, Lorentsen-Wettre, Sweden and the Kajaani FS Metso Automation, Finland.
Although they provide valuable information on a number of fibre properties, since the method is optical, material properties such as elasticity cannot be measured. A recent development in the online measurement of paper quality control is the use of a laser ultrasonic sensor Berkeley Lab, Berkeley, California.
This measures the bending stiffness and out-of-plane shear rigidity. Trials using this device started in This device is an example where material properties can be estimated using ultrasound since they affect the attenuation and wave speed of the ultrasonic wave as it progresses phd thesis ultrasonic studies the material. Hence the use of ultrasound measurement methods can provide rapid, inexpensive, non-destructive and non-intrusive measurements.
A summary of these is given by [3]. One of the reasons given was the emphasis the industry had on quantity rather than quality, phd thesis ultrasonic studies. The economic climate, phd thesis ultrasonic studies, at least in Europe, has changed and it would seem that the emphasis is now on quality and efficiency. The indications for this are from the widespread use phd thesis ultrasonic studies optical devices for monitoring pulp in Scandinavia. However, the correlation between optical fibre characteristics and paper quality has had variable success [4].
This is perhaps because fibre material property measurements are missing. In this case ultrasound based measurements could have the potential to provide the key to increased process phd thesis ultrasonic studies by supplying this missing data.
The aim of this thesis is to investigate the possibilities of being able to use ultrasound to estimate the material properties of pulp fibres in suspension. Given this feedback, one can envisage the paper manufacturing plant of the future having ultrasonic devices for measuring density and elasticity at each stage in the pulp making process.
Each stage could then be adjusted to the type or condition of the wood fibre being fed into the process. The plant would have an online paper quality measurement device, such as the laser ultrasonic sensor, to correlate the information on the individual fibre properties, at each stage in the process, with the output quality of the paper.
The thesis is composed of two parts: firstly a general background and secondly papers that have been either published or submitted for publication.
The general background is divided into an overview of the paper manufacturing process and current testing methods in paper pulp. Some aspects of the physics of ultrasound propagation are discussed before presenting the historical background on the modelling of ultrasound propagation in suspensions. We then present an overview of the simple cylinder scattering SCS model and a summary of the papers is given in Chapter 4.
We discuss some additional issues not tackled in the papers before drawing conclusions. Chapter 2 Paper and Pulp Industry 2. In the chemical pulp manufacturing process, the wood is cooked in a solution of chemicals. The lignin of phd thesis ultrasonic studies wood is made soluble and the fibres separate as whole fibres.
In mechanical pulp manufacturing, the wood fibres may also be exposed to heat and pressure, such as in thermomechanical pulps, phd thesis ultrasonic studies, [5], before being separated by grinding or milling. An overview of these different processes is provided in [6]. This can be done in laboratory setting to assess differences due to wood types or different treatment processes and more recently, the effects of recycling [8].
There is a whole plethora of devices available for monitoring the pulp at different stages of the process. Devices are available for measuring fibre consistency, chemical composition, brightness, yield, and visual features of the fibre that can be measured using optical devices.
Some of which, like the optical devices, are available online. Definitions of these qualities are given in [2]. The first of the two main method used is done by setting the fibre in a v-shaped notch on the tip of a thin capillary tube submersed in water. Water is then allowed flow through the capillary. This water flow is increased until the middle part of the fibre reaches a preset mark [2]. This process has been automated and is available [2]. The SFTI fibremaster, gives an indication of the stiffness through a measurement quantity referred to as bendability.
This is defined as the difference in form factor when measured with high and normal flows in the STFI measuring cell. The form factor is the ratio of the greatest extension of the fibre to the real length of the fibre in the same pro- phd thesis ultrasonic studies plane [9]. The greatest extension is the degree of extension in the projected plane in which the fibre has its greatest bending.
The use of flow and optical measurement, results in the ability of the system to provide a measurement related to the elasticity of the fibre. One of the problems with this method is that the fibre is projected onto two dimensions so that deflection in the third dimension is not considered and hence a source of inaccuracy in the measurement.
Methods or devices measuring the fibre material density in industrial setting have not phd thesis ultrasonic studies found. However, assessment of wood fibre density have been investigated by submerged float techniques by [10].
Hence chemical processes do affect the density of the fibre material, phd thesis ultrasonic studies. The density of the fibre structure depends phd thesis ultrasonic studies a large extent on the wall thickness.
If this collapses the fibre will be denser. Measurement of fibre wall thickness are made by optical devices, such as the Fibermaster, and coarseness values are calculated where coarseness is the mass per unit length. Measurements of shear modulus have not been found for pulp fibres. Chapter 3 Ultrasound in Phd thesis ultrasonic studies 3. As sound propagates through a medium its amplitude decreases as the energy in the wave is absorbed.
If the sound is a pulse then it will contain different frequencies and the shorter the pulse, the more frequencies it will contain, phd thesis ultrasonic studies.
Beth Karlin Ph.D. Thesis Defense
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