| 1. |
- Bygde, Stefan, 1980-
(författare)
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Static WCET Analysis Based on Abstract Interpretation and Counting of Elements
- 2010
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In a real-time system, it is crucial to ensure that all tasks of the system holdtheir deadlines. A missed deadline in a real-time system means that the systemhas not been able to function correctly. If the system is safety critical, this canlead to disaster. To ensure that all tasks keep their deadlines, the Worst-CaseExecution Time (WCET) of these tasks has to be known. This can be done bymeasuring the execution times of a task, however, this is inflexible, time consumingand in general not safe (i.e., the worst-casemight not be found). Unlessthe task is measured with all possible input combinations and configurations,which is in most cases out of the question, there is no way to guarantee that thelongest measured time actually corresponds to the real worst case.Static analysis analyses a safe model of the hardware together with thesource or object code of a program to derive an estimate of theWCET. This estimateis guaranteed to be equal to or greater than the real WCET. This is doneby making calculations which in all steps make sure that the time is exactlyor conservatively estimated. In many cases, however, the execution time of atask or a program is highly dependent on the given input. Thus, the estimatedworst case may correspond to some input or configuration which is rarely (ornever) used in practice. For such systems, where execution time is highly inputdependent, a more accurate timing analysis which take input into considerationis desired.In this thesis we present a framework based on abstract interpretation andcounting of possible semantic states of a program. This is a general methodof WCET analysis, which is language independent and platform independent.The two main applications of this framework are a loop bound analysis and aparametric analysis. The loop bound analysis can be used to quickly find upperbounds for loops in a program while the parametric framework provides aninput-dependent estimation of theWCET. The input-dependent estimation cangive much more accurate estimates if the input is known at run-time.
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| 2. |
- Grip, Björn, 1947-
(författare)
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Samhällsförändring och det ömtåliga hjärtat : En analys av samhälle, ohälsa och hjärtdödlighet i Linköping och Norrköping från 1950-tal till 2000-tal
- 2012
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The study Social Change and the Fragile Heart is an analysis of contemporary history in two neighboring Swedish cities, Linköping and Norrköping. The analysis has been made from a special perspective: the changes in deaths due to heart disease in the age group 50-74 years.The differences in mortality between the two cities is a measurable way to study how well a society functions and is governed. These cities in the county of Östergötland differ historically and socially. This has led to clear differences in socio-economic conditions and even variations in health and mortality that have been to Norrköping’s disadvantage.There is an exception, the 1970’s, when the rise in the numbers of deaths due to heart disease was broken in Norrköping, while the figures continued to increase in the neighboring city, especially among men. Uneasiness about the future and opportunities to make a living grew. This may have influenced health negatively, especially among middle-aged men who feared their jobs were threatened. In Norrköping the textile industry had definitely died in the beginning of the 1970’s. The closing of this industry meant at the same time that poor working conditions and low-paid work were phased out. The earlier rising trend in deaths due to heart diseases was broken, and instead a noticeable decline occurred that was especially clear among women.Deaths due to heart disease in ages 50–74 began to decline generally in the 1980’s and sank significantly in the following decade. The difference between the cities, however, grew from the relatively equal situation of the 1970’s. These are the years during which economic and political power shifted from Norrköping to Linköping. As the regional center and a relatively new university town, Linköping survived the recession of the 1990’s rather well. Simultaneously, Norrköping suffered from what might be called a “social exhaustion depression.” During the last decade of the 20th century long-term unemployment and illness affected far more people than in Linköping. The great transformation from an industrial to a post-industrial society left its mark on Norrköping in the form of increased differences between the cities in the case of premature deaths due to heart disease.
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| 3. |
- Gustafsson Gillbrand, Patrik
(författare)
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Stenbruk : Stenartefakter, råmaterial och mobilitet i östra Mellansverige under tidig- och mellanmesolitikum
- 2018
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis examines artefacts, raw materials and lithic technology between c. 9200–6200 cal BC in Eastern Central Sweden. The overall purpose of this study is to investigate when people first came to Eastern Central Sweden and where they came from. More precisely, it provides a typological, geographical and chronological survey of artefacts and the use of different raw materials. The study deals with assemblages with artefacts from more than thirty archaeologically excavated sites and loose finds in Eastern Central Sweden. The objects consist of chubby pecked axes, core axes, flake axes, shaft hole picks, microliths and micro burins, points, burins, rulers, unifacial blade core, conical cores, micro blade cores, blades, drills, retouched blades and micro blades. The artefacts have been compared with established typologies and chronologies for the rest of the Nordic countries and to some extent Russia and the Baltic States. An analysis of different raw materials present at Early and Middle Mesolithic sites in Eastern Central Sweden was also carried out. The materials are put into a chronological and geographical context. The raw materials included in the study are the non-local rocks flint and Cambrian flint, as well as local raw materials such as quartz, greenstone, local vulcanite, mylonite and red porphyry. From 9200 cal BC there is evidence of the first groups of people in the area, just shortly after that the Weichselian ice cap had withdrawn. Throughout the period studied the artefacts as well as the non-local raw materials exhibit great similarities to those found in the western part of Sweden. The study also shows, regarding the use of different raw materials and presence of certain artefacts, that some major events took place, suggesting a new chronological time frame for the Early- and Middle Mesolithic periods. In addition, a discussion regarding mobility and migration in Eastern Central Sweden during Early Post Glacial time is carried out.
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| 4. |
- Hailesilassie, Biruk Wobeshet
(författare)
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Mechanisms of Blister Formation on Concrete Bridge Decks with Waterprooving Asphalt Pavement Systems
- 2013
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Bridge decks are commonly subjected to harsh environmental conditions that often lead to serious corrosion problems triggered by blisters under the hot mix asphalt bridge deck surfacing and secretly evolving during weather exposure until damage is often detected too late. Blisters may form under both the waterproofing dense mastic asphalt layer or under the waterproofing membrane which is often applied as additional water protection under the mastic asphalt (MA). One of the main technical issues is the formation of blisters under the membrane and asphalt-covered concrete structures caused by a complex mechanism governed by bottom-up pressure and loss of adhesion.A linear viscoelastic finite-element model was developed to simulate time-dependent blister growth in a dense mastic asphalt layer under uniformly applied pressure with and without temperature and pressure fluctuation. A finite element model was developed using ABAQUS with linear viscoelastic properties and validated with a closed form solution from first-order shear-deformation theory for thick plates. In addition, the blister test was conducted on different samples of MA in the laboratory and digital image correlation measurement technique was used to capture the three-dimensional vertical deflection of the MA over time. It was found that the blister may grow continuously under repeated loading conditions over subsequent days.With respect to blistering under waterproofing membranes, mechanical elastic modeling and experimental investigations were performed for three different types of membranes under in-plane stress state. The orthotropic mechanical behavior of a polymer modified bitumen membrane (PBM) was determined from biaxial test data. Finally, blister tests by applying controlled pressure between orthotropic PBMs and concrete plates were performed for studying the elliptical adhesive blister propagation using digital 3D image correlation. The energy calculated from elliptical blister propagation was found comparable to the adhesive fracture energy from standard peeling tests for similar types of PBMs. This indicates that the peeling test assists to evaluate and rank the adhesive properties of different types of membranes with respect to blister formation at room temperature without conducting time consuming and complicated pressurized blister propagation tests using digital 3D image correlation.
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| 5. |
- Henriksson, Mikael
(författare)
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Arkeologiska förväntningar i mötet med ett landskap : Stenålderns Blekinge ur ett kunskapsperspektiv
- 2019
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This study is about archaeological knowledge production. It is also about what kind of impact such knowledge may have on an antiquarian/archaeological practice as well as on society as a whole. The work focuses broadly on Stone Age archaeology and specifically on the middle-Mesolithic Age in the county of Blekinge in the South East of Sweden.Until the late 1990’s, large-scale archaeological excavations in this region were rare. In particular, there were significant gaps in early- and middle-Mesolithic archaeology of other regions. In particular, the study brings up the relationship with the defined Kongemose culture's settlements in Southern Scandinavia. From a knowledge perspective the study discusses how different kinds of methodological practices are important for both archaeology and society, to be able to see and understand a more complete historical picture. Based on this, the focus shifts the role of museums within regional archaeology. The study here argues for a more strategically executed dissemination and presentation of archaeological knowledge towards different stakeholders.
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| 6. |
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| 7. |
- Nilsson, Björn, 1965-
(författare)
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Towards energy efficient protocols for active RFID
- 2007
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The absence of a global standard is a bottleneck when using Radio Frequency Identification (RFID) technology. This thesis explores data communication protocols for Active-RFID regarding their energy efficiency and how they can be suited to fit a large variety of applications.The use of Radio Frequency Identification systems (RFID) is growing rapidly. Today mostly "passive" RFID systems are used because no onboard energy source is needed on the transponders. However, "active" RFID technology, with onboard power sources in the transponders, gives a range of opportunities not possible with passive systems. Besides that Active RFID offers longer working distance between RFID-reader and tag than passive RFID, this also enables the tags to do sensor measurements, calculations and storage even when no RFID-reader is in the vicinity of the tags.To obtain energy efficiency in an Active RFID system the data communication protocol to be used should be carefully designed with energy optimization in mind. This thesis describes how energy consumption can be calculated, to be used in protocol definition, and how evaluation of protocols in this respect can be made. The performance of such a new protocol, in terms of energy efficiency, aggregated throughput, delay, and number of air collisions is evaluated and compared to an existing, commercially available protocol for Active RFID, as well as the IEEE standard 802.15.4 (used e.g. in the Zigbee medium-access layer). Simulations show that, by acknowledging the payload and using deep sleep mode on the tag, the lifetime of a tag is increased.For all types of protocols using an air channel for transmitting and receiving information it is obvious that the utilization of the channel is maximized when no collisions occur. To avoid and minimize collisions in the air interface it is possible to listen to the channel (carrier sense) and know its status. Knowing that the channel is occupied should result in a back-off and a later retry, instead of persistently listening to the channel which would require constant energy consumption. We further study the effect on tag energy cost and packet delay incurred by some typical back-off algorithms (constant, linear, and exponential) used in a contention based CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance) protocols for Active RFID communication. The study shows that by selecting the proper back-off algorithm coefficients (based on the number of tags), i.e. the initial contention window size and back-off interval coefficient, the tag energy consumption and read-out delays can be significantly lowered.
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| 8. |
- Nilsson, Lars R.
(författare)
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Svensk vattenkraft ur ett europeiskt perspektiv : några exempel
- 2005
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The deregulation and integration of the Nordic electricity market into the European Union's internal electricity market will have a major impact on the current Swedish energy system. In particular, Swedish hydropower, the mainstay of Swedish energy, will have a significantly different role under these new conditions. The price of electricity can logically be expected to rise and to fluctuate more on a daily basis, leading to a considerable increase in profits for suppliers as they adapt their operations.The primary purpose of this study, which forms a basis for further research, is to investigate the fundamental operational changes that will occur when profits are maximised along with their economical effects. It contains, in particular, optimisation calculations which show how hydropower plants must be operated to achieve maximum profit under these new constraints. The larger of the two main models, which have been developed to perform this analysis, represents a vital area in Indalsälven, which contains plants owned by Jämtkraft AB in Östersund, while the smaller is of Stångån with plants owned by Tekniska Verken AB in Linköping.The results show that revenue will generally double when hydropower operations are altered from the traditional yearly based focus to a more day to day focus as the border of the energy system expands and the electricity markets of today are integrated into a homogeneous deregulated European one.
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| 9. |
- Sjöstrand, Björn, 1987-
(författare)
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Dewatering aspects at the forming section of the paper machine : Rewetting and forming fabric structure
- 2017
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The underlying motives of the research undertaken here are twofold: to obtain a deeper understanding of the dewatering mechanisms at the forming section of a papermaking machine and to develop numerical models that describe the flow through forming fabrics. More comprehensive knowledge of dewatering in the forming section allows suggestions to be made for improvements that reduce the amount of energy used in the process without affecting the quality of the end product. The objective of this thesis is to answer the following questions:How and why does rewetting occur at the high vacuum suction boxes?How does the structure of the forming fabric affect dewatering at the forming section?Is it possible to create accurate numerical models for forming fabrics, and can these be used to predict the dewatering behaviour of new types of fabrics? Laboratory and pilot studies simulating high vacuum suction boxes were performed together with numerical modelling of the flow of air and water through both the forming fabric and the paper sheet. The conclusion drawn from the pilot study is that rewetting significantly lowers the dryness of the paper sheet exiting the suction boxes. The phenomenon is extremely rapid and is most likely driven by capillary forces. The high speed at which this rewetting occurs makes it difficult to impede by placing the suction boxes closer to the couch pick-up: the solution is more likely to be the use of new and improved designs of the forming fabric. The structure of the forming fabric has been shown to affect the dewatering rate at certain conditions of vacuum dewatering, and can possibly be connected partly to the fact that fibres penetrate the surface of the fabric to varying degrees and partly to the flow resistance of the different fabric structures. Numerical models of high accuracy can be constructed and used to predetermine how new fabric designs would affect dewatering at the forming section. This thesis quantifies aspects of dewatering such as rewetting and the influence of the forming fabric. Understanding these dewatering aspects further provides for the potential enhancement of energy efficiency in the forming section, and thereby the entire papermaking process. The forming fabric can play an important role in improving energy efficiency: rewetting after the high vacuum suction boxes occurs more rapidly than was previously known, so its design might be the only possible way of impeding it. The forming fabric can also improve the rate of dewatering: it is therefore likely that its design will be important in the next stage of developing energy efficiency and thereby play a part in achieving a more sustainable future.
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