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21.
  • Oghazi, Pejvak (författare)
  • Supply chain management : an empirical study on Swedish manufacturing firms' enterprise systems adoption, supply chain integration, competition capability and performance
  • 2009
  • 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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22.
  • Pocorni, Jetro, 1988- (författare)
  • Laser cutting and piercing: Experimental and theoretical investigation
  • 2017
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • This thesis concerns experimental investigations of laser cutting and piercing, with theoretical and practical discussions of the results. The thesis is made up of an introduction to laser cutting and six scientific Papers. These Papers are linked in such a way that each of them studies a different aspect of laser cutting: process efficiency in Paper I, morphology and melt flow on the laser cut front in Papers II, III and IV and laser piercing in Papers V and VI.Paper I investigates the effect of material type, material thickness, laser wavelength, and laser power on the efficiency of the cutting process for industrial state-of-the-art CO2 and fibre laser cutting machines. Here the cutting efficiency is defined in its most fundamental terms: as the area of cut edge created per Joule of laser energy.In Paper II a new experimental technique is presented which has been developed to enable high speed imaging of laser cut fronts produced using standard, commercial parameters. The results presented here suggest that the cut front produced when cutting 10 mm thick medium section stainless steel with a fibre laser and a nitrogen assist gas is covered in humps which themselves are covered in a thin layer of liquid. Paper III presents numerical simulations of the melt flow on a fibre laser ablation-driven processing front during remote fusion cutting, RFC. The simulations were validated with high speed imaging observations of the processing front. The simulation results provide explanations of the main liquid transport mechanisms on the processing front, based on information on the temperature, velocity and pressure fields involved. The results are of fundamental relevance for any process governed by a laser ablation induced front. In Paper IV cutting fronts created by CO2 and fibre lasers in stainless steel at thicknesses between 2 mm and 10 mm have been ‘frozen’ and their geometry has been measured. The resulting three-dimensional shapes have been curve fitted as ninth order polynomials. Various features of the cutting front geometry are discussed, including the lack of correlation of the cut front inclination with either the relevant Brewster angle or the inclination of the striations on the cut edge. In this paper, mathematical descriptions of the cutting fronts are obtained, which can be used as input parameters by any researcher in the field of laser cutting simulations.Paper V investigates the subject of laser piercing. Before any cut is started the laser needs to pierce the material. In this paper the laser piercing process is investigated using a wide range of laser pulse parameters, for stainless steel using a fibre laser. The results reveal the influence of pulse parameters on pierce time and pierced hole diameter. A high speed imaging camera was used to time the penetration event and to study the laser-material interactions involved in drilling the pierced holes. In Paper VI a ‘dynamic’ or ‘moving beam’, laser piercing technique is introduced for processing 15 mm thick stainless steel. One important aspect of laser piercing is the reliability of the process because industrial laser cutting machines are programmed for the minimum reliable pierce time. In this work a comparison was made between a stationary laser and a laser which moves along a circular trajectory with varying processing speeds. High speed imaging was employed during the piercing process to understand melt behavior inside the pierce hole.Throughout this work experimental techniques, including advanced high speed imaging, have been used in conjunction with simulations and theoretical analysis, to provide new knowledge for understanding and improving laser beam cutting and its associated piercing process.
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23.
  • Rundquist, Jonas, 1964- (författare)
  • Outsourcing and knowledge integration in new product development
  • 2009
  • 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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24.
  • Sörqvist, Patrik (författare)
  • The role of working memory capacity in auditory distraction
  • 2010
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The basis of individual differences in susceptibility to auditory distraction has been a research field largely ignored. The current work presents four studies demonstrating that individual differences in working memory capacity (WMC) are related to the magnitude of auditory distraction. The first three reports showed that high WMC attenuates the effects of speech and aircraft noise on reading comprehension and prose memory. The fourth report showed that high WMC attenuates the power of unexpected sound stimulation to capture our attention, but not the interference from changing-state sound streams to seriation processes.Furthermore, the first and the second report showed that the capacity to exclude new, potentially relevant but ultimately irrelevant, materials from memory underlies the relationship between WMC and the effects of speech on reading comprehension/prose memory. Based on these results, a new perspective of WMC called the "sub-process view" was developed, according to which WMC is a compound of functionally distinct subprocesses: some of which are related to auditory distraction. Ten years ago it was not at all clear if cognitive-control processes play a role in auditory distraction, but the studies reported in this thesis strongly suggest that cognitive-control - as reflected in WMC -constitutes a fundamental basis of individual differences in susceptibility to auditory distraction.
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25.
  • Tharani, Soraya (författare)
  • Immigration, security and the public debate on US language policy : A critical discourse analysis of language attitudes in the United States of America
  • 2011
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The narrative of the United States is of a "nation of immigrants" in which the language shift patterns of earlier ethnolinguistic groups have tended towards linguistic assimilation through English. In recent years, however, changes in the demographic landscape and language maintenance by non-English speaking immigrants, particularly Hispanics, have been perceived as threats and have led to calls for an official English language policy. This thesis aims to contribute to the study of language policy making from a societal security perspective as expressed in attitudes regarding language and identity originating in the daily interaction between language groups. The focus is on the role of language and American identity in relation to immigration. The study takes an interdisciplinary approach combining language policy studies, security theory, and critical discourse analysis. The material consists of articles collected from four newspapers, namely USA Today, The New York Times, Los Angeles Times, and San Francisco Chronicle between April 2006 and December 2007. Two discourse types are evident from the analysis namely Loyalty and Efficiency. The former is mainly marked by concerns of national identity and contains speech acts of security related to language shift, choice and English for unity. Immigrants are represented as dehumanised, and harmful. Immigration is given as sovereignty-related, racial, and as war. The discourse type of Efficiency is mainly instrumental and contains speech acts of security related to cost, provision of services, health and safety, and social mobility. Immigrants are further represented as a labour resource. These discourse types reflect how the construction of the linguistic 'we' is expected to be maintained. Loyalty is triggered by arguments that the collective identity is threatened and is itself used in reproducing the collective 'we' through hegemonic expressions of monolingualism in the public space and semi-public space. The denigration of immigrants is used as a tool for enhancing societal security through solidarity and as a possible justification for the denial of minority rights. Also, although language acquisition patterns still follow the historical trend of language shift, factors indicating cultural separateness such as the appearance of speech communities or the use of minority languages in the public space and semi-public space have led to manifestations of intolerance. Examples of discrimination and prejudice towards minority groups indicate that the perception of worth of a shared language differs from the actual worth of dominant language acquisition for integration purposes. The study further indicates that the efficient working of the free market by using minority languages to sell services or buy labour is perceived as conflicting with nation-building notions since it may create separately functioning sub-communities with a new cultural capital recognised as legitimate competence. The discourse types mainly represent securitising moves constructing existential threats. The perception of threat and ideas of national belonging are primarily based on a zero-sum notion favouring monolingualism. Further, the identity of the immigrant individual is seen as dynamic and adaptable to assimilationist measures whereas the identity of the state and its members are perceived as static. Also, the study shows that debates concerning language status are linked to extra-linguistic matters. To conclude, policy makers in the US need to consider the relationship between four factors, namely societal security based on collective identity, individual/human security, human rights, and a changing linguistic demography, for proposed language intervention measures to be successful.
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26.
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27.
  • Hansson, Örjan, 1965- (författare)
  • Studying the views of preservice teachers on the concept of function
  • 2006
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • This thesis consists of an overview of the subject, where in particular five papers are put into a frame. The research conducted for the thesis concerns the views of preservice teachers on the concept of function. Preservice teachers’ conceptions of the function concept are in particular examined in relation to mathematical statements that can be related to different topics on a variety of levels in mathematics; in this research, concept mapping technique is a research tool of interest. Questions concerning preservice teachers’ conceptions of the significance of functions in mathematics, and the presence of functions in school mathematics, are also considered relevant aspects of their views of functions. The final part of the research study includes an intervention study regarding the concept of function, located to a calculus course as one of the concluding courses in mathematics on the educational programme. There is a range of findings from the study that is summarized and further discussed in the overview part of the thesis. One result, is that preservice teachers in their reasoning show signs of knowledge compartmentalization which is an issue of concern in their development of conceptual frameworks rich in meaningful connections. This might have consequences for their abilities to operate in a constructivist environment and reason with their students from different points of view. The function concepts’ large network of relations to other concepts is frequently omitted in the preservice teachers’ reasoning. One reason for this is that to preservice teachers, properties of functions seem to be results of isolated procedures, associated with operational conceptions rather than structural conceptions of functions. The findings imply that preservice teachers should encounter functions in a variety of context, to develop their views of the concept of function – including frameworks rich of meaningful relations – and realize that the concept of function is one of the underlying concepts of mathematics, and an important concept to introduce to their future students. The preservice teachers’ reflections concerning functions in school mathematics contribute to emphasize the significance of the process of transformation of subject matter knowledge to pedagogical content knowledge. Further results of the research study, and an outline of the implications, are included in the concluding discussion of the overview part of the thesis. The preservice teachers participating in the study are enrolled in a four and a half year teacher preparation program in mathematics and science, grades 4 to 9. The five papers included in the thesis, describe parts of a larger study essentially conducted until the sixth term during the concluding mathematics courses of the program.
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28.
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29.
  • Dahlén, Leon (författare)
  • Numerical and experimental study of performance of a hydraulic motor
  • 2003
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The aim of this study was to develop an understanding of the fluid properties that influence the efficiency of hydraulic systems in a steady-state, especially components in hydrostatic transmission systems under different running conditions. The aim has also been to investigate and model the sources of losses in hydraulic machines, in order to estimate the losses, taking fluid properties into account. Finally, the technique of optimization has been introduced in order to improve the efficiency of a distributor valve in a radial piston hydraulic motor, Marathon M200. From an experimental field-test, which was performed on a belt conveyer using a hydrostatic transmission system, the overall efficiency of the hydrostatic transmission was compared when using a mineral oil, Shell Tellus TX 68, a synthetic fluid, Mobil SHC 526, and a vegetable fluid, Binol Hydrap II. The experimental field-test showed that vegetable and synthetic fluids improve the efficiency compared to mineral oil. The three fluids have the same viscosity but experimental tests showed that the temperature ()- and pressure() -viscosity coefficient differs between them. It was also found that the pressure-viscosity coefficient () of mineral oil was higher compared to vegetable and synthetic fluids. The proposed steady-state model gives greater accuracy regarding overall efficiency than the Wilson model, when examining fluid properties that differ in other aspects than their viscosity. The study has focused on losses in lubricated sliding contacts within a radial piston hydraulic motor, Marathon M200, and an analysis of the losses has been made using the finite element method (FEM). A FEM software package, Solvia, which takes into account fluid properties, such as temperature- and pressure- viscosity coefficient, heat conduction and specific heat, has been used to simulate the behaviour and to estimate the losses in tribological contact. This approach of simulation has been applied to two different tribological contact within the hydraulic motor: to a journal bearing contact and to a hydrostatic annular multi-recess plane thrust bearing. By using an FEM software package linked to an optimization algorithm, the losses in the tribological contact in a distributor valve were reduced significantly. The study shows that the optimized geometry of the distributor valve in the motor can successfully be improved, with regard to losses, by small changes in the geometry. Combining an FEM software package with the optimization routine offers an effective tool for designers to simulate and improve the efficiency of a hydraulic unit.
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30.
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