| 1. |
- Oghazi, Pejvak
(författare)
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Supply chain management : an empirical study on Swedish manufacturing firms' enterprise systems adoption, supply chain integration, competition capability and performance
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Today’s marketplace is more fiercely competitive than ever before. Globalization, continual technological advances, and an ever-changing customer demand for new products have brought about new managerial practices and business models. New management approaches and unique business models emerge and fade constantly as managers strive to help their companies succeed in this less-predictable business world. However, communication and information technologies are offering new opportunities for businesses to compete in the global arena with a variety of tools. One area that has benefited the most from new technologies is supply chain management (SCM). Today, SCM could be a single, integrated function that is responsible for all aspects of material flow, as well as financial and information exchange among business partners within the chain. For several years, pundits have observed that the very nature of competition is changing. Some experts have even claimed that the day is rapidly approaching when companies will no longer compete against other companies. Instead, they foresaw a world in which supply chains will compete with other supply chains for market supremacy. The possibilities in a supply chain are indeed astounding, but the challenges that lie along the path to achieve excellence in supply chain integration are equally formidable. Companies are investing in systems, tweaking measures, and looking to technology and people to find the key to more effective interorganizational cooperation. To help future managers achieve success in this arena, this PhD project articulates a support measure intended to underscore the importance of supply chain integration for the focal firm in terms of better competition capability and performance. A proposed research model and seven hypotheses were developed in this PhD project. A survey was conducted among Swedish manufacturing companies, which resulted in 422 complete and usable responses, with an effective response rate of 65.8%. The hypotheses were tested using Structural Equation Modeling. Additionally, the moderating and mediating effects were also tested in this study. The results obtained for this thesis suggest that a significant relationship exists between the perceived benefits of SCM integration and the adoption of different enterprise systems. With regard to the core issues of this thesis regarding the connection between supply chain integration, competition capability, and firm performance, the findings strongly indicate a positive and direct relationship between these constructs. Furthermore, the present study also determined that the competition capability of a firm mediates the relationship between supply chain integration and the performance of the firm. Consequently, firms that strive to achieve superior performance, and thus establish a strong position in the marketplace, should consider a genuine integration level with their supply chain partners. For this reason, the adoption of different enterprise systems facilitates the achievement of a high-level integration across the supply chain. It is also important to recognize that establishment of a high integration level is essential to achieving superior performance and a strong competition capability in the market today and in the future.
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| 2. |
- Rundquist, Jonas, 1964-
(författare)
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Outsourcing and knowledge integration in new product development
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis deals with two aspects of knowledge needed for new product development; theaccess to external knowledge through outsourcing of NPD and the integration of knowledgedeveloped when outsourcing activities in the NPD process. As modern products competing onincreasingly international markets call for both complex and specialized knowledge, it isbecoming more important to take an outward perspective of knowledge, searching for externalknowledge sources, in order to be competitive. But it is also important for the firm to take aninward perspective on integration of the knowledge achieved from external sources in order tosecure the knowledge gained.Outsourcing of New Product Development (NPD) refers to the outsourcing of activities fordeveloping new products (goods and/or service), where all or the innovative part of the NPDprocess is purchased externally according to a contract from organizational units separatefrom the outsourcing firm. This means that the service to develop a whole or a part of a newproduct is outsourced. This definition implies that (A) the outsourced activity shall be aninnovative (strongly contributing to the newness) part of the NPD process, (B) the outsourcedactivity was previously conducted internally, and (C) the activity shall be purchased andregulated in a contractual agreement between the organizations.Knowledge integration refers to the process of acquiring, sharing, and making use ofknowledge by combining it with previous knowledge in order to create new value. Becauseknowledge possessed in collaborating firms is often complementary, it is important tocombine it with previous knowledge in the firm. Therefore knowledge integration is chosenthroughout the thesis as the term for the overall process.Based on transaction costs theory, resource based and knowledge based perspectives twomajor issues are investigated. First, the identification of which factors are the most importantfor firms when making the decision to outsource activities in the NPD process. Second, theestablishment of the importance for knowledge integration of external knowledge in the firm,and to find what role level of involvement among staff plays for efficiently achievingknowledge integration.The thesis is a compilation thesis (with six appended papers) based on findings from threequantitative studies and a longitudinal case study (presented in two of the appended papers).Using cases from and samples of medium-sized manufacturing firms with in-house NPD itwas found that, while cost has been traditionally considered the most important factor foroutsourcing in general, search for external knowledge is found to have a greater importancewhen intangible processes as NPD is object for outsourcing. It is also found that thematicknowledge is the most important type of knowledge to efficiently integrate to achieve highinnovation performance and that a higher degree of processes and culture supportinginvolvement, increase knowledge integration when outsourcing activities in the NPD process.
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| 3. |
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| 4. |
- Abdikalikova, Zamira
(författare)
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Some new results concerning boundedness and compactness for embeddings between spaces with multiweighted derivatives
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This Doctoral Thesis consists of five chapters, which deal with a new Sobolev type function space called the space with multiweighted derivatives. This space is a generalization of the usual one dimensional Sobolev space. As basis for this space serves some differential operators containing weight functions.Chapter 1 is an introduction, where, in particular, the importance to study function spaces with weights is discussed and motivated. In Chapter 2 we prove some new estimates for each function in a Tchebychev system. In order to be able to study compactness of the embeddings from Chapter 3 such estimates are crucial.In Chapter 3 we rewrite and present some results of L. D. Kudryavtsev, where he investigated one dimensional Sobolev spaces. Moreover, in this chapter we rewrite and discuss some analogous results by B. L. Baidel'dinov for generalized Sobolev spaces. These results are not available in the Western literatures in this way and they are crucial for the proofs of the main results in Chapter 4. In Chapter 4 we prove some embedding theorems for these new generalized Sobolev spaces. The main results of Kudryavtsev and Baidel'dinov about characterization of the behavior of functions at a singularity take place in weak degeneration of the spaces. However, with the help of our new embedding theorems we can extend theseresults to the case of strong degeneration.The main aim of Chapter 5 is to establish boundedness and compactness of the embedding considered in Chapter 4.In Chapter 4 basically only sufficient conditions for boundedness of this embedding were obtained. In Chapter 5 we obtain necessary and sufficient conditions for boundedness and compactness of this embedding and the main results are proved in a different way.
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| 5. |
- Aitomäki, Yvonne
(författare)
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Online fibre property measurements : foundations for a method based on ultrasound attenuation
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents the foundations of a method for estimating fibre properties of pulp suitable for online application in the pulp and paper industry. In the pulp and paper industry, increased efficiency and greater paper quality control are two of the industry's main objectives. It is proposed that online fibre property measurements are a means of achieving progress in both of these objectives. Optical based systems that provide valuable geometric data on the fibres and other pulp characteristics are commercially available. However, measurements of the elastic properties of the fibres are not currently implemented using these systems. To fill this gap an ultrasound based system for measuring the elastic properties of the wood fibres in pulp is proposed. Ultrasound propagation depends on the elastic properties of a solid. Hence attenuation measurements from suspensions of fibres depend on their elastic properties. The method is based on solving the inverse problem where the output is known and the objective is to establish the inputs. In this case, attenuation is measured and a model of attenuation based on ultrasound scattering is developed. A search algorithm is used for finding elastic properties that minimize the error between the model and measured attenuation. The results of the search are estimates of the elastic properties of the fibres in suspension. The results show resonance peaks in the attenuation, in the frequency region tested, for fibres with radii of the order of 10 microns. These peaks are found in both the measured and modelled attenuation spectra. Further investigation of these resonances suggests that they are due to modes of vibration in the fibre where the fibre modelled as an infinitely long cylinder. These resonances are shown to aid in the identification of the elastic properties. The attenuation is found to depend heavily on the geometry of the fibres. Hence fibre geometry, which can be obtained from online optical fibre measurement system, provides the key to extracting the elastic properties from the attenuation signal. Studies are also carried out on the effect of viscosity on attenuation as well as the differences in attenuation between hollow and solid synthetic fibres in suspensions. The measurement method is also applied to hardwood and softwood Kraft pulps. The results of these studies show that using the model derived in the thesis and attenuation measurements, estimates of the elastic properties can be obtained. The elastic property estimates for synthetic fibres agree well with values from other methods. The elastic property estimates for pulps require further validation due to the difficulty in comparing between different testing methods and different types of pulp. The conclusions, based on the work so far and under three realisable conditions, are that the shear modulus and the transverse Young's modulus of pulp fibres can be measured. Once these conditions are met a system based on this method can be implemented. By doing this the industry would benefit from the increase in paper quality control and energy saving such system could provide.
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| 6. |
- Amer, Eynas
(författare)
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Pulsed laser ablation studied using digital holography
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Pulsed digital holographic interferometry has been used to study the plume and the shock wave generated in the laser ablation process on different targets under atmospheric air pressure. A pulsed Nd-YAG laser system (pulse duration 12 ns) has been used both for ablating the material (wavelength 1064 nm) and for measurement (wavelength 532 nm). Digital holograms were recorded for different time delays using collimated laser light passed through the volume along the target. Numerical data of the integrated refractive index field were calculated and presented as phase maps. The Radon inversion has been used to estimate the 3D refractive index fields measured from the projections assuming rotational symmetry. Intensity maps have been calculated from the recorded digital holograms and used to calculate the attenuation of the probing laser beam by the ablated plume. Qualitative and quantitative information have been extracted from both the phase map and the intensity map to help describing the laser ablation process. Also 3D information about the induced plume has been obtained by numerical reconstruction of the digital holograms at different planes along the plume. The amount of released energy due to laser impact on a PCBM target has been estimated using the point explosion model. The released energy is normalized by the incident laser pulse energy and the energy conversion efficiency between the laser pulse and the target has been calculated and it seems to be constant around 80 %. The 3D refractive index fields have been used to calculate the shock wave front density and the electron number density distribution within the induced plasma. The electron number densities are found to be in the order of 1018 cm-3 and decay at a rate of 3x1015 electrons/cm3ns. The effect of the laser spot diameter on the shock wave generated in the ablation process of a Zn target has been studied. The induced shock wave has an ellipsoidal shape that approaches a sphere for decreasing spot diameter. A model was developed that approaches the density distribution that facilitates the derivation of the particle velocity field. The method provides quantitative results that are discussed; in particular a comparison with the point explosion theory. The effect of the physical properties of the target on the laser ablation process has been studied. The comparison of the laser ablation of Zn and Ti shows that different laser ablation mechanisms are observed for the same laser settings and surrounding gas. At a laser fluence of 5 J/cm2, phase explosion appears to be the ablation mechanism in case of Zn, while for Ti normal vaporisation seems to be the dominant mechanism. The results show that pulsed digital holographic interferometry is a promising technique to give a physical picture and increase the understanding of the laser ablation process in a time resolved manner.
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| 7. |
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| 8. |
- Andersson, Christian
(författare)
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Biobased production of succinic acid by Escherichia coli fermentation
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The prospects of peak oil, climate change and the dependency of fossil carbon have urged research and development of production methods for the manufacture of fuels and chemicals from renewable resources (biomass). The present thesis illustrates different aspects of biobased succinic acid production by a metabolically engineered E. coli strain. The main areas of the thesis are sugar utilisation and feedstock flexibility, and fermentation inhibition, both due to toxic compound derived from the raw material and the fermentation products themselves.The first part of this thesis aimed to investigate the fermentation characteristics of AFP184 in a medium consisting of corn steep liquor, inorganic salts and different sugar sources without supplementation with high-cost nutrients such as yeast extract and peptone. The effects of different sugars, sucrose, glucose, fructose, xylose, equal mixtures of glucose-fructose and glucose-xylose, on succinic acid production kinetics and yields in an industrially relevant medium were investigated. AFP184 was able to utilise all sugars and sugar combinations except sucrose for biomass generation and succinate production. Using glucose resulted in the highest yield, 0.83 (g succinic acid per g sugar consumed anaerobically). Using a high initial sugar concentration resulted in volumetric productivities of almost 3 g L-1 h-1, which is above estimated values for economically feasible production. However, succinic acid production ceased at final concentrations greater than 40 g L-1. To further increase succinic acid concentrations, fermentations using NH4OH, NaOH, KOH, K2CO3, and Na2CO3 as neutralising agents were performed and compared. It was shown that substantial improvements could be made by using alkali bases to neutralise the fermentations. The highest concentrations and productivities were achieved when Na2CO3 was used, 77 g L-1 and 3 g L-1 h-1 respectively. A gradual decrease in succinate productivity was observed during the fermentations, which was shown to be due to succinate accumulation in the broth and not as a result of the addition of neutralising agent or the subsequent increase in osmolarity.To maintain high succinate productivity by keeping a low extracellular succinic acid concentration fermentations were interrupted and cells recovered and resuspended in fresh media. By removing the succinate it was possible to maintain high succinic acid productivity for a prolonged time. Cells subjected to high concentrations of succinate were also able to regain high productivity once transferred into a succinate-free medium.In the last part of the thesis succinic acid production from softwood dilute acid hydrolysates was demonstrated. This study involved establishing the degree of detoxification necessary for growth and fermentation using industrial hydrolysates. Detoxification by treatment with lime and/or activated carbon was investigated and the results show that it was possible to produce succinate from softwood hydrolysates in yields comparable to those for synthetic sugars.The work done in this thesis increases the understanding of succinic acid production with AFP184, illustrate its limitations, and suggests improvements in the current technology with the long term aim of increasing the economical feasibility of biochemical succinic acid production.
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| 9. |
- Andersson, Urban
(författare)
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An experimental study of the flow in a sharp-heel Kaplan draft tube
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This research project was originally part of a package (Turbine-99 Draft Tube) that had a mutual goal, to improve the understanding of draft tube flow and establish Best Practise Guidelines for simulation of draft tube flow.The draft tube is situated after the runner in a Hydropower turbine to recover as much of the remaining head and kinetic energy as possible before the water leaves the turbine. The case is fully turbulent, and because of the adverse pressure gradient with risk for separation, periodic inlet conditions from the runner with different degrees of swirl causes the draft tube flow to be difficult to predict. Therefore, unambiguous design criterions are lacking, and the slightly contradicting recommendations indicate that the standard rules give conservative, rather than optimal, designs. This thesis gives some background on draft-tube flows in general and discusses the parameters and flow conditions relevant to the Turbine-99 draft tube in some detail. The main goal of the thesis is to provide extensive experimental data on a well-defined sharp-heel draft-tube flow. The data bank has served as validation data for the simulation challenge presented by the Turbine-99 workshops in Porjus (June 1999), Älvkarleby (June 2001) and Porjus (December 2005).The experimental data and some numerical results are also available as an application challenge in the Qnet database (managed by Ercoftac), as a validation case for flow simulations.The experimental data consists of visualisations, pressure measurements and velocity measurements. These methods give a good qualitative picture of the flow pattern in the draft tube with quantitative data at selected cross section that can be used to validate the flow simulations. The first two workshops focused on mean quantities of pressure and velocities; however, phase resolved measurements have been added to add value to the experimental data.In addition to the experimental validation case, there is one paper that deals with loads on the draft tube, which affect the construction lifetime. Since the hydropower stations are expected to have a long total technical lifetime with a number of refurbishments, these questions will grow in importance over the next decades.
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| 10. |
- Beeri, Guy
(författare)
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Some mathematical, numerical and engineering aspects of composite structures and perforated solids
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this doctoral thesis in engineering mathematics we present some new modeling, numerical and engineering aspects and results concerning composite structures and perforated solids.The thesis consists of five papers, which are divided into three parts. Part A functions as an introduction where we look into some of the mathematical, numerical and engineering aspects of the effective in-plane elastic properties of periodic structures. We focus on one- and two-component composites and, in particular, we discuss locally anisotropic perforated structures. Moreover, we describe how the elastic properties of such and more general structures can be calculated. Finally, we present bounds and relations between different effective moduli.In Part B we study twelve of the simplest structures belonging to the class of one-component structures with holes and which, in addition, are three-fold rotational symmetric. We look into the effective elastic in-plane properties such as effective bulk and shear moduli and the so-called Vigdergauz constants. A comparative overview of all of these properties is given. Furthermore, we derive low-density asymptotics and present numerical data from finite element calculations. We also show that several of the studied structures have optimal elastic properties in the limit when the volume fraction of the connected material goes to zero. Finally, some remarks on the manufacturability of the structures are made.In Part C, which is divided into three papers, we continue to explore the effective properties of periodic structures. In paper [C1] we introduce a new model for estimating the elastic effective properties of regular hexagonal honeycombs. In contrast to previous cases, with this model we introduce a new formula, which match and complement the results obtained by Vigdergauz in 1999 in an essential way. Furthermore, by comparing some of the results with numerical finite element computations we find an improved formulae which enable us to estimate the effective properties with an accuracy better than one percent. In paper [C2] we study the effective elastic properties of regular triangular honeycombs. In particular, we obtain some simple approximate formulae for the corresponding Vigdergauz constants with accuracy better than one percent for all densities. In paper [C3] we study a scale of two-component composite structures of equal proportions with infinitely many microlevels. The structures are obtained recursively and we find that their effective conductivities are power means of the local conductivities.
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