| 1. |
- Boudreau, Jonna, 1980-
(författare)
-
New methods for evaluation of tissue creping and the importance of coating, paper and adhesion
- 2013
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The creping process and the conditions on the Yankee cylinder dryer are key factors in a tissue paper mill, and they therefore need to be kept under good control in order to maintain a high and uniform quality. To this end it would be valuable to be able to make on-line measurements of Yankee coating thickness as well as the crepe structure of the tissue paper. The adhesion of paper to the cylinder affects the creping process and more information about the parameters that affect the adhesion is therefore of interest. To perform trials on a full scale or in a pilot plant is very costly and laboratory creping equipment is therefore sought after in order to be able to measure the adhesion force.The coating layer for use on the cylinder was analysed. It contained a large amount of carbohydrates and could not be considered transparent. The thickness of the coating layer was measured on a laboratory cylinder with a method based on fluorescence. An optical brightener was added to the coating chemicals and the coating layer was subjected to UV-radiation. The intensity of the light emitted by the optical brightener was measured and gave an indication of the thickness of the coating layer. The equipment has to be further investigated before it is possible to implement the new sensor on-line.New creping equipment and an adhesion method were developed for use on a laboratory scale. The equipment can operate with different creping angles and the force needed to crepe the paper can be measured. The highest creping force was obtained for papers of high grammage, low dryness at adhesion, high drainability, high fines content and high hemicellulose content.A more direct method is to analyse the structure of the produced paper. Measurements were made on a tissue paper with an optical fibre sensor while the paper was travelling at low speed. The collected signal was mathematically analysed and the characteristic wavelength was calculated for different paper samples. These values were close to the wavelengths measured with an off line method by a commercial crepe analyser.
|
|
| 2. |
- Barros, Gustavo Gil, 1976-
(författare)
-
Influence of Substrate Topography on Ink Distribution in Flexography
- 2006
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The printability of paper in flexography is largely dependent on the topographical characteristics of the substrate. Topography imaging instruments make it possible to obtain three-dimensional scans of paper surfaces that can be further used to calculate valuable quality parameters. The primary aim of the work described in this thesis has been to identify and isolate structural properties of the paper surface which significantly influence the ink distribution during printing and limit the subsequently attainable print quality.OptiTopo is an optical imaging technique which provides precise and fast topographic scans of both printed and unprinted paper surfaces. The potential and limitations of the technique have been evaluated. The optical requirements on the substrate for an accurate and precise topographic scan were determined. Detail-rendering was substantially improved using a custom-designed restoring filter, and a new enhanced spatial resolution range was established. A combination of further algorithm improvements made it possible also to obtain reflectance-factor-calibrated intensity images of scanned printed surfaces.Serious deficiencies affecting the quality of flexographic prints may appear in the form of local unprinted areas (UCA) in a full-tone print, generally caused by incomplete ink transfer. An algorithm detecting and quantifying local uncovered area was developed, tested and successfully integrated with the OptiTopo instrument. A UCA occurrence frequency distribution, indicating the percentage of the uncovered area at a certain topographical elevation, was calculated for different prints. The topographic characteristics of the uncovered areas clearly indicate that surface depressions are the primary cause of uncovered areas in flexographic printing.Four different predictive models based on topography thresholding were proposed and tested using two independent quality judgement criteria. These quality indices took into account both the amount and location of the predictions. A deeper understanding of the topographical features governing UCA occurrence was established with a proposed ink bridging effect. The total risk of non-ink-covered areas in flexography printing due to topographical features was estimated.The overall influence of paper topography on the flexography printability of full-tone areas was studied and its importance for the ink distribution assessed. The impacts of printing plate hardness, printing pressure, anilox cylinder volume and substrate roughness were quantified. Two typical flexography patterns were identified and their origin discussed: sub-millimetre elongated structures and millimetre-scale blotches.
|
|
| 3. |
- Johnson, Johanna, 1970-
(författare)
-
Aspects of Flexographic Print Quality and Relationship to some Printing Parameters
- 2008
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Flexographic printing is a common printing method in the packaging field. The printing method is characterized primarily by the flexible printing plate and the low viscosity inks which make it suitable for use on almost any substrate. The object of this study was to obtain further knowledge of the some important mechanisms of flexographic printing and how they influence the print quality. The thesis deals with printing primarily on board and liner but also on newsprint with water-borne ink using a full-scale flexographic central impression (CI) printing press. Several printing trials have been performed with a focus on the chemical interaction between the ink and substrate and the physical contact between the ink-covered printing plate and the substrate. Multicolour printing exposes the substrate to water from the water-containing ink. The emphasis was to investigate the relation between print quality and water-uptake of the paper surface with heat and water. Printing trials was carried out on substrates possessing a hydrophobic, and also a rather hydrophilic surface using a regular commercial water-borne ink. The favorable effect which water or surfactant solution had on the hydrophobic substrate with regard to print mottle could depend on its surface compressibility in combination with the hydrophobic nature of its surface that could affect the wetting properties. Conventional printing involves physical contact between plate and ink and between ink and substrate. A method for measuring the dynamic nip pressure using thin load cells is presented. Print quality was influenced by the plate material. A correction procedure taking into account the size of the sensor was developed in order to estimate the maximum dynamic pressure in the printing nip. An attempt was made to identify essential mechanical and chemical parameters, and also geometrical properties of the plate that affected print quality. Laboratory printing trials were carried out and a multivariate analysis was applied for evaluation of print quality data. The impact of the plate properties on print quality was evident. The essential properties of the plate that influence print quality were the small-scale roughness and long-scale roughness.
|
|
| 4. |
- Jonhed, Anna, 1975-
(författare)
-
Properties of modified starches and their use in the surface treatment of paper
- 2006
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The papermaking industry uses a large amount of starch each year, both as a wet-end additive and as a rheological modifier in surface sizing and coating colors. It is important to be able to reduce the amount of chemicals used in the papermaking and surface treatment process, to reduce costs and to make the process even more efficient. Interest in new high-performance starches is great. By using these new types of starches, improved recycling of barrier products may be obtained as well as a reduction in the use of synthetic sizing agents. The objectives of this work were to understand the behavior of temperature-responsive hydrophobically modified starches, where the solubility in water simply can be adjusted by temperature or by polymer charge, to improve the barrier properties, like the water vapor permeability, mechanical properties and water resistance (Cobb and contact angle) of papers surface sized by starch-containing solutions, and to investigate the potential for industrial use of these temperature-responsive starches. It was demonstrated that the temperature-responsive starches phase separate upon cooling and, depending on the charge density of the starch, a particulate precipitation or a gel-like structure was obtained. The starch with zero net charge showed a larger increase in turbidity than the starch with a cationic net charge, indicating that particulate precipitation is favored by a zero net charge and that the formation of a gel network is favored by charged starch molecules. Further, the starches formed inclusion complexes with surfactants, giving stabilization to the starches in the presence of surfactants. The net charge density of the starch and the charge of the surfactant determined whether or not an inclusion complex would form between them. Important mechanisms for the stability of the starch seemed to be formation of mixed micellar-like structures between the hydrophobic chain of the starch and the surfactant along the starch backbone in addition to formation of inclusion complexes between the starch and the surfactant. The hydrophobically modified starches showed higher hydrophobic surface character when applied to the paper surface above the critical phase separation temperature than with application at room temperature. Free films of the temperature-responsive starches showed good barrier against oxygen, but no barrier against water vapor. The mechanical properties decreased with addition of glycerol to the films.
|
|
| 5. |
- Kjellgren, Henrik, 1970-
(författare)
-
Influence of paper properties and polymer coatings on barrier properties of greaseproof paper
- 2007
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Greaseproof paper has a dense structure and therefore provides a natural barrier against materials like fat and oils. The barrier is obtained by extensive refining of the pulp. This refining is however a costly operation, not only in terms of direct costs for the refining but also in terms of indirect costs because the energy consumption for the drying of the paper is affected by the refining. A full-scale trial was performed to investigate the role of the pulp with respect to the energy demand and the barrier properties of the final papers. Paper made of 100% sulphite pulp with a low degree of refining exhibited the lowest energy consumption at a given level of air permeance. In addition, the effect of refining on the air permeance was compared with that of calendering. The calendering affected the air permeance less than the refining. The papers produced in the full-scale trial were later used as substrates for coatings and for detailed studies of the paper structure. Coating with chitosan was examined on a bench-scale and on a pilot scale. The studies showed that greaseproof paper can be upgraded with an oxygen barrier, but also that suitable coating techniques are lacking for the application of the coating in a sufficient amount. The influence of the base paper on the barrier properties of chitosan-coated paper was investigated in another study, in which it was found that greaseproof paper possesses a unique coating hold-out which cannot be met by other types of paper with a more open structure. It was also found that the coated paper had a lower oxygen permeability than the chitosan coating itself, and this indicates that the dense surface layer of greaseproof paper contributed to the oxygen permeability of the coated paper. The pore volume fraction of the greaseproof paper was found to be approximately 40% and it is therefore surprising that its air permeance is so low. To bring understanding to this question, the structure of greaseproof paper was studied using several methods. It was found that the structure was dominated by very small pores with a median diameter of <0.3 µm. The fraction of closed pores was also substantial. A porosity gradient was also found, indicating that the papers used in the study had a closed surface. The hypothesis that the surface layer of the paper contributed to the oxygen barrier was tested in an experiment in which greaseproof paper was extrusion-coated with polyethylene. The oxygen permeability was measured at 0%, 50% and 90% relative humidity, and the permeability was found to increase with increasing moisture content. Because only the cellulose layer in the paper and not the polyethylene layer in the coating is affected by moisture, this result supports the hypothesis that the surface layer of the paper contributed to the oxygen barrier properties of the coated paper.
|
|
| 6. |
- Kvarnlöf, Niklas, 1971-
(författare)
-
Activation of dissolving pulps prior to viscose preparation
- 2007
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The conventional viscose manufacturing process is a mature process that needs to be improved with respect to its environmental impact and its production cost structure. Therefore a research study has been done with the aim to improve the reactivity of the dissolving pulp used, in order to reduce the chemical demand in the viscose process and thus reduce the cost and indirectly the environmental impact.The work described in this thesis has shown that it is possible to enhance the pulp reactivity and to use less carbon disulphide in the production of viscose, while maintaining a good quality viscose dope, by two entirely different pretreatment methods, one chemical and one enzymatic.The chemical method used pressurized oxygen after the mercerisation step, which increased the reactivity of the alkali cellulose. The viscose dopes produced from the pressurized oxygen treated alkali cellulose had lower filter clogging values, Kw, compared to conventionally produced viscoses. The temperature and the oxygen treatment time of the alkali cellulose were however crucial for the viscose quality.The best performing enzyme of several tested was a cellulase of the mono component endoglucanase preparation Carezyme®. This enzymatic treatment was optimized with respect to viscose dope preparation. The study showed that the enzyme treatment could be carried out under industrially interesting conditions with respect to temperature, enzyme dose and reaction time. A re-circulation study of the enzyme showed that it was possible to re-use the spent press water from the enzymatic treatment step several times, and thus lower the production cost. Some of the viscose process stages were modified to properly fit the enzymatically treated dissolving pulp and a comparison between viscose made from enzyme-treated pulp and viscose made from conventional pulp, showed that the enzyme-treated samples had a lower filter clogging value, Kw. This indirectly indicates that the enzyme pretreatment could reduce the carbon disulphide charge in the viscose manufacturing process. An initial study of how the Carezyme® influenced different cellulosic sources was also performed.
|
|
| 7. |
- Pérez Prieto, Héctor
(författare)
-
HISTORIEN OM RÄVEN OCH ANDRA BERÄTTELSER : Om klasskamrater och skolan på en liten ort – ur ett skol- och livsberättelse perspektiv
- 2006
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Pérez Prieto, Héctor 1999: Historien om räven och andra berättelser. Om klasskamrater och skolan på en liten ort – ur ett skol- och livsberättelseperspektiv. Pedagogisk Forskning i Uppsala, nr 37, januari 2000.Berättelser om mötet med klasskamraterna och vad det innebar att växa upp och gå i skola i Åby, en liten jord- och skogsbrukspräglad ort står i fokus för rapporten. Berättelserna skapades med hjälp av livshistorie-intervjuer med fyra ungdomar, som har gått i samma klass under hela skoltiden, tio år efter att de hade avslutat skolan. De f.d. elevernas berättelser organiseras och presenteras med hjälp av både en individuell livsberättelse och en mosaik formad av samtliga ungdomars kollektiva och personliga minnen. Identitetskonstruktionen är central i berättelserna: De lyfter fram hur dessa ungdomar i interaktion med varandra hanterade de omständigheter under vilka de levde och i och med det agerandet formade sig själva och bidrog till konstruktionen av dessa omständigheter, men också om hur de i efterhand, ’med facit i handen’ väljer att framställa sig själva och den kontext i vilken de levde.Den bild av skolan som berättelserna ger grundas på elevernas agerande och erfarenheter och den lyfter fram hur klasskamraternas agerande konstruerade klassens stökighet, dess väl sammansvetsade grupperingar och dess ointresse för studierna, dvs. hur de med sitt agerande konstituerade de konkreta förutsättningar för kunskapsinhämtande, vidare studier, gemenskap och identitetsskapande.
|
|
| 8. |
- Svanholm, Erik, 1975-
(författare)
-
Printability and Ink-Coating Interactions in Inkjet Printing
- 2007
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Inkjet is a digital printing process where the ink is ejected directly onto a substrate from a jet device driven by an electronic signal. Most inkjet inks have a low viscosity and a low surface tension, which put high demands on the coating layer’s porosity and absorbency characteristics.The aim of this study has been to gain an increased knowledge of the mechanisms that control the sorption and fixation of inkjet inks on coated papers. The focus has been on printability aspects of high print quality (although not photographic quality) laboratory-coated inkjet papers for printers using aqueous-based inks.Papers coated solely with polyvinyl alcohol (PVOH) and starch presented excellent gamut values and good print sharpness over the uncoated substrate, due to good film-forming characteristics observed by light microscopy and ESCA. ESEM analyses showed the complexity and variation of PVOH surface structures, which has probably explained the wide scatter in the colour-to-colour bleed results. Pure PVOH coatings also gave a surface with high gloss variations (2-8 times greater than that of commercial inkjet papers), prolonged ink drying time, and cracked prints when using pigmented inks. When an amorphous silica gel pigment (with broad pore size distribution) was used in combination with binder, a new structure was formed with large pores in and between the pigments and a macro-roughness generated by the large particles. The inkjet ink droplets could quickly penetrate into the large pores and the time for surface wicking was reduced, which was beneficial for the blurriness. However, the macro-roughness promoted bulk spreading in the coarse surface structure, and this tended to increase the line width. Finally, when the ink ends up within the coating, the colorant is partly shielded by the particles, and this reduced the gamut area to some extent. The binder demand of the silica pigments was strongly related to their pore size distributions. Silica gel required two to three times the amount of binder compared to novel surfactant-templated mesoporous silica pigments (with small pores and narrow pore size distribution). This finding was attributed to the significant penetration of PVOH binder into the pores in the silica gel, thereby, increasing its binder demand. Furthermore, this binder penetration reduced the effective internal pore volume available for rapid drainage of the ink vehicle. Consequently, the surfactant-templated pigments required significantly lower amounts of binder, and gave improvements in print quality relative to the commercial pigment.
|
|
| 9. |
|
|
| 10. |
- Abadzhiev, Andrey, 1980-
(författare)
-
Wood We Change? : Business Model Innovation Towards Sustainability Transitions: Studying the Wood Construction Industry
- 2021
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Innovations based on sustainable technologies have been widely considered as a remedy for addressing societal and environmental problems in many industries. However, the large-scale adoption of such innovations goes beyond technology and requires organizing the business in a way that drive industrial transformations across actors and system layers, such as market structures, institutional frames, consumer behavior, and business values. The aim of this dissertation is to understand how industrial firms organize for system change towards sustainability. The study is a compilation of two papers within the same research context: the development of sustainable technology in the construction industry. The overlapping unit of analysis for both papers is business model innovation. Paper I examines how industry firms combine and complement business models with different innovation types to accelerate sustainable technology. Paper II identifies how a change in the business model and value creation logic that occur on a firm level accelerate sustainable technology and shape the socio-technical system. Together, both papers help paint a more complete picture of the business model role in transitions towards sustainability. The theoretical frame of this dissertation spans several domains: business model, innovation management, and sustainability transitions. Building on a multi-disciplinary premise, the study takes into account the organizational and the systemic parts of the change process by linking the company perspective (business models) to the wider governance of sustainability transitions. The findings underline the importance of business models that combine production efficiency with higher customer engagement and more collective value creation for driving larger-scale transitions toward sustainability. Moreover, business models in combination with different innovation types, such as product, process and positioning, act together and complement each other to achieve high sustainability and business outcomes.
|
|
| 11. |
- Abbas, Muhammad Tahir
(författare)
-
Improving the Energy Efficiency of Cellular IoT Device
- 2023
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cellular Internet of Things (CIoT) has emerged as a promising technology to support applications that generate infrequent data. One requirement on these applications, often battery-powered devices, is low energy consumption to enable extended battery life. Narrowband IoT (NB-IoT) is a promising technology for IoT due to its low power consumption, which is essential for devices that need to run on battery power for extended periods. However, the current battery life of NB-IoT devices is only a few years, which is insufficient for many applications. This thesis investigates the impact of energy-saving mechanisms standardized by 3GPP on battery life of NB-IoT devices. The main research objective is to classify and analyze existing energy-saving solutions for CIoT and examine their limitations, to study the impact of standardized energy-saving mechanisms on the battery life of NB-IoT devices, both in isolation and combined, and to provide guidelines on how to configure NB-IoT devices to reduce energy consumption efficiently. The research aims to provide a deeper understanding of the effect of energy-saving mechanisms and best practices to balance energy efficiency and performance of NB-IoT devices. Applying the proposed solutions makes it possible to achieve a battery life of 10~years or more for CIoT devices.
|
|
| 12. |
- Abelsson, Anna, 1971-
(författare)
-
Simulering som lärande inom prehospital akutsjukvård
- 2017
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Den prehospitala akutsjukvården är ett komplext kunskapsfält som innebär att vårdaren skall kunna bemöta patient och närstående, bedöma skada, sjukdom och den aktuella situationen samt avgöra vilka vårdåtgärder som skall prioriteras.Patientens lidande kan lindras genom att vårdaren tränar färdigheter i ett prehospitalt kontext. Detta främjar en god och säker vård samt stärker patientens möjligheter till överlevnad.Resultatet visar på behovet av simulering inom prehospital akutsjukvård. Med simulering lär sig vårdaren att hantera realistiska, dynamiska och komplexa vårdsituationer, vilket skapar kunskaper, färdigheter och erfarenheter av omhändertagande av patient drabbad av högenergitrauma. Simuleringens utformning och miljö skapar förutsättningar för lärandet vilket framkommer i interventionsstudien.Utifrån resultatet i föreliggande forskning utvecklas en modell för lärande med hjälp av simulering.
|
|
| 13. |
- Abrahamsen Grøndahl, Vigdis, 1964-
(författare)
-
Patients’ perceptions of actual care conditions and patient satisfaction with care quality in hospital
- 2012
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- There are theoretical and methodological difficulties in measuring the concepts of quality of care and patient satisfaction, and the conditions associated with these concepts. A theoretical framework of patient satisfaction and a theoretical model of quality of care have been used as the theoretical basis in this thesis. Aim. The overall aim was to describe and explore relationships between person-related conditions, external objective care conditions, patients’ perceptions of quality of care, and patient satisfaction with care in hospital. Methods. Quantitative and qualitative methods were used. In the quantitative study (I-III), 528 patients (83.7%) from eight medical, three surgical and one mixed medical/surgical ward in five hospitals in Norway agreed to participate (10% of total discharges). Data collection was conducted using a questionnaire comprising four instruments: Quality from Patients’ Perspective (QPP); Sense of Coherence scale (SOC); Big Five personality traits – the Single-Item Measures of Personality (SIMP); and Emotional Stress Reaction Questionnaire (ESRQ). In addition, questions regarding socio-demographic data and health conditions were asked, and data from ward statistics were included. Multivariate statistical analysis was carried out (I-III). In the qualitative study 22 informants were interviewed (IV). The interviews were analysed by conventional content analysis. Main findings. Patients’ perceptions of quality of care and patient satisfaction ranged from lower to higher depending on whether all patients or groups of patients were studied. The combination of person-related and external objective care conditions explained 55% of patients’ perceptions of quality of care (I). 54.7% of the variance in patient satisfaction was explained, and the person-related conditions had the strongest impact, explaining 51.7% (II). Three clusters of patients were identified regarding their scores on patient satisfaction and patients’ perceptions of quality of care (III). One group consisted of patients who were most satisfied and had the best perceptions of quality of care, a second group of patients who were less satisfied and had better perceptions, and a third group of patients who were less satisfied and had the worst perceptions. The qualitative study revealed four categories of importance for patients’ satisfaction: desire to regain health, need to be met in a professional way as a unique person, perspective on life, and need to have balance between privacy and companionship (IV). Conclusions. Patients’ perceptions of quality of care and patient satisfaction are two different concepts. The person-related conditions seem to be the strongest predictors of patients’ perceptions of quality of care and patient satisfaction. Registered nurses need to be aware of this when planning and conducting nursing care. There is a need of guidelines for handling over‑occupancy, and of procedures for emergency admissions on the wards. The number of registered nurses on the wards needs to be considered. Healthcare personnel must do their utmost to provide the patients with person‑centred care.
|
|
| 14. |
- Afzal, Zeeshan, 1991-
(författare)
-
Life of a Security Middlebox : Challenges with Emerging Protocols and Technologies
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Internet of today has intermediary devices known as middleboxes that perform more functions than the normal packet forwarding function of a router. Security middleboxes are a subset of these middleboxes and face an increasingly difficult task to perform their functions correctly. These middleboxes make many assumptions about the traffic that may not hold true any longer with the advent of new protocols such as MPTCP and technologies like end-to-end encryption.The work in this thesis focuses on security middleboxes and the challenges they face. We develop methods and solutions to help these security middleboxes continue to function correctly. In particular, we investigate the case of using MPTCP over traditional security infrastructure as well as the case of end-to-end encryption. We study how practical it is to evade a security middlebox by fragmenting and sending traffic across multiple paths using MPTCP. We then go on to propose possible solutions to detect such attacks and implement them. The potential MPTCP scenario where security middleboxes only have access to part of the traffic is also investigated and addressed. Moreover, the thesis contributes a machine learning based approach to help security middleboxes detect malware in encrypted traffic without decryption.
|
|
| 15. |
- Agin, Sol, 1989-
(författare)
-
Communicating climate action : Combining action repertoires and linguistic repertoires in social movement message construction
- 2022
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The climate crisis is one of the largest global challenges that humanity has ever faced. Despite the scientific consensus on the threat, action is not occurring on the pace or level needed to stave off the consequences. As climate change is made up by complex and conjoined causes and effects, the issue is also riddled with communicative challenges which those calling for action need to tackle. Climate change communication research has, however, mainly focus on how traditional news media frame the climate change issue and overlooks climate activist and movement groups. This despite these actors being key for shifting public perceptions and public opinion. Although research on other communication actors exist, it is far from extensive and the research field overlooks the publics perceptions of the sender in relation to the construction of climate messages. Through survey data and an experiment, this doctoral thesis explores the public’s inclination towards different protest action repertoires and addresses the research gap in the climate movement message construction. Herein, the actions and words of three subgroups within the larger environmental movement is considered as one part of a larger message whole. The groups chosen action repertoires are viewed as part of the activists’ performed message and the linguistic communication styles created by lexical choices related to emotional appeals are part of the activists’ verbal/textual message. The results indicate that there is much to be gained from adhering to an alignment between lexical choices and action repertoires. Alignment may be key for understanding why some movement subgroups are successful in inspiring certain actions whilst others inspire other actions. Communication-action alignment is a way to approach the interconnectedness of actions and words for complex and abstract issues that require message recipients to construct consonant mental models to break potential cognitive dissonance.
|
|
| 16. |
- Agnemyr, Helena, 1984-, et al.
(författare)
-
Gör Vågen! : Samhällsentreprenörskap med värmländska förtecken
- 2011
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Rapporten handlar om samhällsentreprenörskap med värmländska förtecken. Idén om samhällsentreprenörer ges i rapporten sammanhang och perspektiv i en diskussion om tidsandan. Rapporten handlar både om teori och praktik. Den bygger på litteraturstudier och på samtal och dialoger med forskare, regionala aktörer och inte minst värmländska samhällsentreprenörer. Rapportens rubrik har hämtas från ett återberättande av ett möte om vad regeringen tänkte göra för näringslivet. Det förlösande svaret på en avslutande fråga om vad regeringen borde göra blev ”Gör vågen!”. Anekdoten berättades vid en av de två workshopar med värmländska samhällsentreprenörer som genomfördes under arbetet med rapporten. Tankar om samhällsentreprenörskapet syfte och sammanhang eller dess själ och djupare mening kan möjligen sammanfattas i två dikter av Tage Danielsson, nämligen; För den trötta samhällskroppen, vore kanske bästa boten, ifall tankarna från toppen kom från roten Och En droppe i livets älv har ingen kraft att flyta själv. Det ställs ett krav på varenda droppe. Hjälp till att hålla de andra oppe!
|
|
| 17. |
- Alaqra, Ala Sarah
(författare)
-
The Wicked Problem of Privacy : Design Challenge for Crypto-based Solutions
- 2018
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Data privacy has been growing in importance in recent years, especially with the continuous increase of online activity. Researchers study, design, and develop solutions aimed at enhancing users’ data privacy. The wicked problem of data privacy is a continuous challenge that defies straightforward solutions. Since there are many factors involved in data privacy, such as technological, legal, and human aspects, we can only aim at mitigating rather than solving this wicked problem. Our aim was to focus on human aspects for designing usable crypto-based privacy-enhancing solutions. In this thesis, we followed a user centered design method by using empirical qualitative means for investigating user’s perceptions and opinions of our solutions. Most of our work has focused on redactable signatures in the cloud context within the eHealth use-case. Redactable signatures are a privacy enhancing scheme allowing to remove parts of a signed document by a specified party for achieving data minimization without invalidating the respective signature.We mainly used semi-structures interviews and focus groups in our investigations. Our results yielded key HCI considerations as well as guidelines of different means for supporting the design of future solutions.
|
|
| 18. |
- Alaqra, Ala Sarah
(författare)
-
Tinkering the Wicked Problem of Privacy : Design Challenges and Opportunities for Crypto-based Services
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Data privacy has been growing in importance in recent years, especially with the constant increase of online activity. Consequently, researchers study, design, and develop solutions aimed at enhancing users' data privacy. The wicked problem of data privacy is a dynamic challenge that defies straightforward solutions. Since there are many factors involved in data privacy, such as technological, legal, and human aspects, we can only aim at mitigating rather than solving this wicked problem.Our aim was to explore challenges and opportunities with a focus on human aspects for designing usable crypto-based privacy-enhancing technologies (PETs). Mainly, there were three PETs in the cloud context included in our studies: malleable signatures, secret sharing, and homomorphic encryption. Based on the three PETs, services were developed within European research projects that were the scope of our user studies. We followed a user-centered design approach by using empirical qualitative and quantitative means for collecting study data. Our results and tinkering conveyed (i) analysis of different categories of user's perspectives, mental models, and trade-offs, (ii) user requirements for PET services, and (iii) user interface design guidelines for PET services. In our contributions, we highlight considerations and guidelines for supporting the design of future solutions.
|
|
| 19. |
- Alfredsson, Stefan, 1976-
(författare)
-
A Cross-Layer Perspective on Transport Protocol Performance in Wireless Networks
- 2012
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Communication by wireless technologies has seen a tremendous growth in the last decades. Mobile phone technology and wireless broadband solutions are rapidly replacing the last-hop wireline connectivity for telephones and Internet access. Research has, however, shown that Internet traffic can experience a performance degradation over wireless compared to wired networks. The inherent properties of radio communication lead to a higher degree of unreliability, compared to communication by wire or fiber. This can result in an increased amount of transmission errors, packet loss, delay and delay variations, which in turn affect the performance of the main Internet transport protocols TCP and UDP. This dissertation examines the cross-layer relationship between wireless transmission and the resulting performance on the transport layer. To this end, experimental evaluations of TCP and UDP over a wireless 4G downlink system proposal are performed. The experiment results show, in a holistic scenario, that link-level adaptive modulation, channel prediction, fast persistent link retransmissions, and channel scheduling, enables the transport protocols TCP and UDP to perform well and utilize the wireless link efficiently. Further, a novel approach is proposed where a modified TCP receiver can choose to accept packets that are corrupted by bit errors. Results from network emulation experiments indicate that by accepting and acknowledging even small amounts of corrupted data, a much higher throughput can be maintained compared to standard TCP.
|
|
| 20. |
- Alfredsson, Stefan, 1976-
(författare)
-
TCP in Wireless Networks: Challenges, Optimizations and Evaluations
- 2005
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents research on transport layer behavior in wireless networks. As the Internet is expanding its reach to include mobile devices, it has become apparent that some of the original design assumptions for the dominant transport protocol, TCP, are approaching their limits. A key feature of TCP is the congestion control algorithm, constructed with the assumption that packet loss is normally very low, and that packet loss therefore is a sign of network congestion. This holds true for wired networks, but for mobile wireless networks non-congestion related packet loss may appear. The varying signal power inherent with mobility and handover between base-stations are two example causes of such packet loss. This thesis provides an overview of the challenges for TCP in wireless networks together with a compilation of a number of suggested TCP optimizations for these environments. A TCP modification called TCP-L is proposed. It allows an application to increase its performance, in environments where residual bit errors normally give a degraded throughput, by making a reliability tradeoff. The performance of TCP-L is experimentally evaluated with an implementation in the Linux kernel. The transport layer performance in a 4G scenario is also experimentally investigated, focusing on the impact of the link layer design and its parameterization. Further, for emulation-based protocol evaluations, controlled packet loss and bit error generation is shown to be an important aspect.
|
|
| 21. |
- Algervik, Robert, 1981-
(författare)
-
Embedding Theorems for Mixed Norm Spaces and Applications
- 2010
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is devoted to the study of mixed norm spaces that arise in connection with embeddings of Sobolev and Besov type spaces. We study different structural, integrability, and smoothness properties of functions satisfying certain mixed norm conditions. Conditions of this type are determined by the behaviour of linear sections of functions. The work in this direction originates in a paper due to Gagliardo (1958), and was further developed by Fournier (1988), by Blei and Fournier (1989), and by Kolyada (2005). Here we continue these studies. We obtain some refinements of known embeddings for certain mixed norm spaces introduced by Gagliardo, and we study general properties of these spaces. In connection with these results, we consider a scale of intermediate mixed norm spaces, and prove intrinsic embeddings in this scale. We also consider more general, fully anisotropic, mixed norm spaces. Our main theorem states an embedding of these spaces to Lorentz spaces. Applying this result, we obtain sharp embedding theorems for anisotropic Sobolev-Besov spaces, and anisotropic fractional Sobolev spaces. The methods used are based on non-increasing rearrangements, and on estimates of sections of functions and sections of sets. We also study limiting relations between embeddings of spaces of different type. More exactly, mixed norm estimates enable us to get embedding constants with sharp asymptotic behaviour. This gives an extension of the results obtained for isotropic Besov spaces by Bourgain, Brezis, and Mironescu, and for anisotropic Besov spaces by Kolyada. We study also some basic properties (in particular the approximation properties) of special weak type spaces that play an important role in the construction of mixed norm spaces, and in the description of Sobolev type embeddings. In the last chapter, we study mixed norm spaces consisting of functions that have smooth sections. We prove embeddings of these spaces to Lorentz spaces. From this result, known properties of Sobolev-Liouville spaces follow.
|
|
| 22. |
- Algervik, Robert, 1981-
(författare)
-
Embedding Theorems for Mixed Norm Spaces and Applications
- 2008
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is devoted to the study of mixed norm spaces that arise in connection with embeddings of Sobolev and Besov type spaces. The work in this direction originates in a paper due to Gagliardo (1958), and was continued by Fournier (1988) and by Kolyada (2005). We consider fully anisotropic mixed norm spaces. Our main theorem states an embedding of these spaces into Lorentz spaces. Applying this result, we obtain sharp embedding theorems for anisotropic fractional Sobolev spaces and anisotropic Sobolev-Besov spaces. The methods used are based on non-increasing rearrangements and on estimates of sections of functions and sections of sets. We also study limiting relations between embeddings of spaces of different type. More exactly, mixed norm estimates enable us to get embedding constants with sharp asymptotic behaviour. This gives an extension of the results obtained for isotropic Besov spaces $B_p^\alpha$ by Bourgain, Brezis, and Mironescu, and for Besov spaces $B^{\alpha_1,\dots,\alpha_n}_p$ by Kolyada. We study also some basic properties (in particular the approximation properties) of special weak type spaces that play an important role in the construction of mixed norm spaces and in the description of Sobolev type embeddings.
|
|
| 23. |
- Almlöf Ambjörnsson, Heléne, 1968-
(författare)
-
Mercerization and Enzymatic Pretreatment of Cellulose in Dissolving Pulps
- 2013
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis deals with the preparation of chemically and/or enzymatically modified cellulose. This modification can be either irreversible or reversible. Irreversible modification is used to prepare cellulose derivatives as end products, whereas reversible modification is used to enhance solubility in the preparation of regenerated cellulose.The irreversible modification studied here was the preparation of carboxymethyl cellulose (CMC) using extended mercerization of a spruce dissolving pulp. More specifically the parameters studied were the effect of mercerization at different proportions of cellulose I and II in the dissolving pulp, the concentration of alkali, the temperature and the reaction time. The parameters evaluated were the degree of substitution, the filterability and the amount of gel obtained when the resulting CMC was dissolved in water. Molecular structures of CMC and its gel fractions were analysed by using NIR FT Raman spectroscopy. It was found that the alkali concentration in the mercerization stage had an extensive influence on the subsequent etherification reaction. FT Raman spectra of CMC samples and their gel fractions prepared with low NaOH concentrations (9%) in the mercerization stage indicated an incomplete transformation of cellulose to Na-cellulose before carboxymethylation to CMC. Low average DS values of the CMC, i.e. between 0.42 and 0.50 were obtained. Such CMC dissolved in water resulted in very thick and semi solid gum-like gels, probably due to an uneven distribution of substituents along the cellulose backbone. FT Raman spectra of CMC samples and their gel fractions mercerized at higher alkaline concentration, i.e. 18.25 and 27.5% in the mercerization stage, indicated on the other hand a complete transformation of cellulose to Na-cellulose before carboxymethylation to CMC. Higher average DS values of the CMC, i.e. between 0.88 and 1.05 were therefore obtained. When dissolved in water such CMC caused gel formation especially when prepared from dissolving pulp with a high fraction of cellulose II.The reversible modification studied was the dissolution of cellulose in NaOH/ZnO. Here the effect of enzyme pretreatment was investigated by using two mono-component enzymes; namely xylanase and endoglucanase, used in consecutive stages. It was found that although the crystallinity and the specific surface area of the dissolving pulp sustained minimal change during the enzymatic treatment; the solubility of pulp increased in a NaOH/ZnO solution from 29% for untreated pulp up to 81% for enzymatic pretreated pulp.
|
|
| 24. |
- Almlöf, Heléne, 1968-
(författare)
-
Extended Mercerization Prior to Carboxymethyl Cellulose Preparation
- 2010
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Carboxymethyl cellulose (CMC) is produced commercially in a two-stage process consisting of a mercerization stage, where the pulp is treated with alkali in a water alcohol solution, followed by an etherification stage in which monochloroacetic acid is added to the pulp slurry. In this thesis an extended mercerization stage of a spruce ether pulp was investigated where the parameters studied were the ratio of cellulose I and II, concentration of alkali, temperature and retention time. The influence of the mercerization stage conditions on the etherification stage, were evaluated as the degree of substitution (DS) of the resulting CMC and the filterability of CMC dissolved in water at a concentration of 1%. The DS results suggested that the NaOH concentration in the mercerization stage was the most important of the parameters studied. When the NaOH concentration in the mercerization step was low (9%), a high cellulose II content in the pulp used was found to have no negative impact on the DS of the resulting CMC compared with pulps with only cellulose I. However, when the NaOH concentration was high (27.5%), pulps with high content of cellulose II showed a lower reactivity than those with only cellulose I with respect to the DS of the CMC obtained after a given charge of NaMCA. The results obtained from the filtration ability study of CMC water solutions suggested that both the amount of cellulose II in the original pulp and the temperature had a negative influence on the filtration ability whereas the NaOH concentration in the mercerization stage had a positive influence. The filtration ability was assumed to be influenced highly by the presence of poorly reacted cellulose segments. A retention time between 1-48 h in the mercerization stage had no effect on either the DS or the filtration ability of the CMC. Using NIR FT Raman spectroscopy molecular structures of CMC and its gel fraction were analyzed with respect to the conditions used in the extended mercerization stage. Here it was found that the alkaline concentration had a very strong influence on the following etherification reaction. FT Raman spectra of CMC samples and their gel fractions prepared with low NaOH concentrations (9%) in the mercerization stage indicated an incomplete transformation of cellulose to Na-cellulose before carboxymethylation to CMC. Low average DS values of the CMC, i.e. between 0.42 and 0.50, were yielded. Such CMC dissolved in water caused very thick and semi solid gum-like gels, probably due to an uneven distribution of substituting groups along the cellulose backbone. FT Raman spectra of CMC mercerized with alkaline concentrations at 18.25 and 27.5% in the mercerization stage indicated, however, that all of the cellulose molecules were totally transferred to CMC of high DS, i.e. between 0.88 and 1.05. When dissolved in water such CMC caused gels when they were prepared from ether pulp with a high fraction of cellulose II.
|
|
| 25. |
- Alriksson, Björn
(författare)
-
Ethanol from lignocellulose : Management of by-products of hydrolysis
- 2009
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Fuel ethanol can be produced from lignocellulosic materials, such as residues from agriculture and forestry. The polysaccharides of lignocellulose are converted to sugars by hydrolysis and the sugars can then be fermented to ethanol using microorganisms. However, during hydrolysis a wide range of by-products are also generated. By-product formation can affect ethanol yield and productivity. Management of by-products of hydrolysis is therefore important in the development of commercially viable production of cellulosic ethanol. Detoxification of inhibitory dilute-acid lignocellulose hydrolysates by treatment with Ca(OH)2 (overliming) efficiently improves the fermentability, but is associated with drawbacks like sugar degradation and CaSO4 precipitation. In factorial designed experiments, in which pH and temperature were varied, dilute-acid spruce hydrolysates were treated with Ca(OH)2, NH4OH or NaOH. The concentrations of sugars and inhibitory compounds were measured before and after the treatments. The fermentability was examined using the yeast Saccharomyces cerevisiae and compared with reference fermentations of synthetic medium without inhibitors. The treatment conditions were evaluated by comparing the balanced ethanol yield, which takes both the degradation of sugars and the ethanol production into account. Treatment conditions resulting in excellent fermentability and minimal sugar degradation were possible to find regardless of whether Ca(OH)2, NH4OH or NaOH was used. Balanced ethanol yields higher than those of the reference fermentations were achieved for hydrolysates treated with all three types of alkali. As expected, treatment with Ca(OH)2 gave rise to precipitated CaSO4. The NH4OH treatments gave rise to a brownish precipitate but the amounts of precipitate formed were relatively small. No precipitate was observed in treatments with NaOH. The findings presented can be used to improve the effectiveness of alkali detoxification of lignocellulose hydrolysates and to minimize problems with sugar degradation and formation of precipitates. Overexpression of different S. cerevisiae genes was investigated with the aim to engineer a biocatalyst with increased inhibitor tolerance. Overexpression of YAP1, a gene encoding a transcription factor, conveyed increased resistance to lignocellulose-derived inhibitors as well as to a dilute-acid hydrolysate of spruce. Recombinant Aspergillus niger expressing the Hypocrea jecorina endoglucanase Cel7B was cultivated on spent lignocellulose hydrolysate (stillage). The fungus simultaneously removed inhibitors present in the stillage and produced higher amounts of endoglucanase than when it was grown in a standard medium with comparable monosaccharide content. The concept can be applied for on-site production of enzymes in a cellulose-to-ethanol process and facilitate recycling of the stillage stream.
|
|
