| 1. |
- Abdalla, Suliman A
(author)
-
Architecture and circuit design of photon counting readout for X-ray imaging sensors
- 2007
-
Licentiate thesis (other academic/artistic)abstract
- Hybrid pixel array detectors for X-ray imaging are based on different technologies for sensor and readout electronics. The readout electronics are based on standard CMOS technologies that are experiencing continuously rapid improvements by means of down-scaling the feature sizes, which in turn lead to higher transistor densities, lower power consumption, and faster circuits. For pixel-array imaging sensors the improvements in CMOS technology opens up new possibilities of integrating more functionality in the pixels for local processing of the sensor data. However, new issues related to the tight integration of both analog and digital processing circuits within the small area of a pixel must also be evaluated. The advantages of down-scaling the CMOS technology can be utilized to increase the spatial resolution by reducing the pixel sizes. Recent research indicates however that the bottleneck in reaching further spatial resolution in X-ray imaging sensors may not be limited by the circuit area occupied by the functions necessary in the pixels, but are instead related to problems associated with charge-sharing of charges generated by the sensor which are distributed over a neighbourhood of pixels and will limit the spatial resolution and lead to a distortion of the energy spectrum. In this thesis a mechanism to be implemented in the readout circuits is proposed in order to suppress the charge-sharing effects. The proposed architecture and its circuit implementation are evaluated with respect to circuit complexity (area) and power consumption. For a photon-counting pixel it is demonstrated that the complete pixel, with charge-sharing suppression mechanism, can be implemented using 300 transistors with an idle power consumption of 2.7μW in a 120nm CMOS technology operating with a 1.2V power supply. The improvements in CMOS technology can also be used for increasing the range of applications for X-ray imaging sensors. In this thesis, an architecture is proposed for multiple energy discrimination, called color X-ray imaging. The proposed solution is the result of balancing the circuit complexity and the image quality. The method is based on color sub-sampling with intensity biasing. For three-level energy discrimination, that corresponds to color imaging systems for visible light with R, G, and B color components, the increase in circuit complexity will be only 20% higher than that for the Bayer method but results in significantly better image quality. As the circuit complexity in the digital processing within each pixel is increased, the digitally induced noise may play an increasingly important role for the signal-to-noise ratio in the measurements. In this thesis an initial study is conducted regarding how the digital switching noise affects the analog amplifiers in the photon-counting pixel.
|
|
| 2. |
- Abikari, Masoome
(author)
-
Young consumers’ emotions towards emerging e-banking technology : A multi-perspective approach
- 2024
-
Licentiate thesis (other academic/artistic)abstract
- Banks appear to be interested in enhancing their effectiveness and efficiency by developing e-banking technology, i.e., the provision of banking products and services through electronic channels. However, the successful implementation of e-banking technology depends on how consumers perceive such technology and how they are probably provoked to adopt it. Considering emerging e-banking technologies, knowledge of the salient influential factors affecting consumer adoption is crucial for banks. Studies have analysed these factors from different perspectives, such as attribute- and barrier-based perspectives. Attribute-based factors pertain to the perceived or expected characteristics of e-banking technology, whereas barrier-based factors refer to factors that can hinder or delay the adoption of e-banking technology. Despite the absence of consensus on these factors, there is a predominant focus on the functional aspects of this technology, often neglecting the emotional experience of consumers. Consumers’ emotions in the e-banking context mainly refer to hedonic motivation, defined as positive emotions such as fun, pleasure, and enjoyment arising from the usage of e-banking technology. While examining hedonic motivation has provided valuable insights into the adoption of such technology, further studies are required to examine the relationship among consumers’ emotions, particularly negative ones arising from different kinds of appraisals. Accordingly, this thesis aims to examine the influence of consumers’ emotions towards emerging e-banking technology on their intention to adopt such technology, with a specific emphasis on negative emotions from attribute and barrier-based perspectives. Applying Structural equation modelling (SEM), the empirical results draw attention to the influential role of different types of negative emotions in the adoption of emerging e-banking technology. From the attribute-based perspective, the empirical results demonstrate an association between loss emotions and consumers’ behavioural intention to adopt emerging e-banking technology, through effort expectancy and performance expectancy. From a barrier-based perspective, the results indicate that deterrence emotions can be positively associated with consumers’ perceived risk. This, in turn, influences their behavioural intention to adopt emerging e-banking technology. The results also reveal the influence of deterrence emotions on consumers’ perceived risk, even in the presence of positive emotions. These results suggest the importance of considering various categories of negative emotions when examining consumers’ intention to adopt emerging e-banking technology.
|
|
| 3. |
- Ahlbeck, Bengt
(author)
-
Musikutbildningen och examination vid Kungl. Musikaliska Akademien under "Pehr Frigel-epoken", 1796-1842
- 1994
-
Licentiate thesis (other academic/artistic)abstract
- In this lecentiate disseratation music education and examination at the Royal Academy of Music (KMA) during the period 1796-1842, hear called the Frigel era, is described. The theory of culture provides a general perspective for the disign of the dissertation and the illustration of the issues. A model of analysis, which is a method of investigation rather than a finished model, forms a point ot departure in my attempt to demonstrate that education and examination had a double effect in society. It meant a cultural pluralism rather than a secularization. Education during the Frigel era starts with an Elementary Singing School, but after 1815 its professional aim becomes gradually more obvious. Subjects during the period in question are the theory of music, singing, piano and organ. The examination for a post at school, at sixth form college or senior high school and in church is extensive. During a twenty-year period 80 music teachers, 90 precentors and 600 organists are examined. Important issues discussed in this essay concern education content, education quality and examination demands related to school and church activities and also to the improtance of education in the development of society.
|
|
| 4. |
- Ahlin, Karin
(author)
-
Approaching the intangible benefits of a boundary object
- 2014
-
Licentiate thesis (other academic/artistic)abstract
- Today´s information society is constantly increasing the quantity of digital information that organisations have access to and depend on. Despite this dependency, few descriptions exist of the benefits which this digital information can provide the organisation with. Examples of what the organisation can use the information for include business intelligence or in a business process. The absence of such benefit descriptions results in missed opportunities in organisational management and a failure to cultivate the artefact. In terms of a practical operational work role, this means that the artefact just exists and that there are no decisions, communication and discussions connected to it. Earlier research about benefits in the Information Systems field is focused on describing the process of finding benefit factors from different IT investments and how these investments can be measured financially. The result of this was that it was only the measurable benefits that were taken into consideration. Later benefit management research has shown interest in the intangible benefit factors as well and added this as an activity in the evaluation process. Today´s view is that the benefit consists both of tangible and intangible benefit factors. This thesis emphasises benefit factors found by means of qualitative research in organisations producing Technical Information (TI). TI isinformation connected to goods and services and is a part of a product. The intangible benefit factors found which are connected to TI are semantic interoperability and knowledge. Semantic interoperability is beneficial both for the organisation and the individuals – in the first case exemplified by a uniform working process and in the second as efficiency in the internal communication. Knowledge also provides benefit both to the organisation and the individuals – the organisation can operate without depending on certain individuals and information gives the individuals mobility in their profession.The next part in the thesis discusses information management´simpact on benefit factors. In the case of an autocratic approach, it is the organisation that benefits most, whereas a decentralised management style provides the individual co-workers with a greater number of benefit factors. This proves that information management is an important and decisive ingredient, and that it affects benefit factors.One step in the direction of converting the intangible benefit factors into tangible ones is to visualise them. In this work the theoreticallens provided by a boundary object has been used. This lens adds a qualitative view on cross-boundary information and has efficiency approaches. These approaches are the syntactical, semantic andpragmatic. Via interpretations from the thesis´s two empirical cases, those approaches are "measured" by interpretations and visualised by the three leaves of a clover. This gives the opportunity to describewhat information efficiency, in this case connected to a positiveexpectation, can contribute to the organisation or the individuals. By this procedure, different cases or time aspects can be compared,thereby providing a basis for decision-making, communication and discussion. Future research in this area can be made in different directions – one is to investigate whether the intangible benefit factors can be turned into measurable ones. In this way, the internal organisation can be provided with better knowledge of the digital information's impact. Another research direction is to investigate how the passage of time affects the benefit factors that digital information gives the organisation.
|
|
| 5. |
- Ahmad, Jawad, 1985-
(author)
-
Screen Printed Large Area Sensors for Pressure Distribution Monitoring in Wheelchairs
- 2019
-
Licentiate thesis (other academic/artistic)abstract
- A sedentary lifestyle can induce health related problems including pressure ulcers. Prolonged sitting inadequacies constitute a risk for pressure ulcer to many individuals, in particular people with disabilities and reduced mobility. The measurement of distributed pressure and detection of irregular sitting postures are essential in prevention of the risk of developing pressure ulcers.In this thesis, a screen-printed pressure sensor for a large area is presented, with the objective of measuring the distributed pressure of a seated person in a wheelchair. The conductors and interdigital patterns are printed with silver-based ink. A blend of a non-conductive and a low resistive ink is used for customized resistance for an optimal sensing range of the pressure sensor. The effect of moisture and temperature are realized in an environment chamber. For characterization, other key performance tests such as repeatability, drift and flexibility are carried out. The surface morphology is carried out for structural analysis of printed samples. The sensor data is acquired and processed using an 8-bit ATmega-2560 microcontroller and wirelessly transmitted to a PC for post-processing, storage and analysis. For real-time data presentation of distributed pressure points, a GUI has been developed to display the values obtained from the large area sensor. The detection of four sitting postures; forward leaning, backward leaning, left leaning and right leaning along with a normal sitting posture is attained. An analysis for stretchable printed tracks has been conducted to investigate the changes in electrical resistance using elongation tests, surface morphology and EDS. The optimal curing time and temperature were investigated to manufacture stretchable conductive tracks.In summary, the contributions in this thesis provides an effective approach regarding pressure distribution measurement and recognizing irregular sitting postures for wheelchair users.
|
|
| 6. |
- Ahmad, Naeem
(author)
-
Modelling and optimization of sky surveillance visual sensor network
- 2012
-
Licentiate thesis (other academic/artistic)abstract
- A Visual Sensor Network (VSN) is a distributed system of a largenumber of camera sensor nodes. The main components of a camera sensornode are image sensor, embedded processor, wireless transceiver and energysupply. The major difference between a VSN and an ordinary sensor networkis that a VSN generates two dimensional data in the form of an image, whichcan be exploited in many useful applications. Some of the potentialapplication examples of VSNs include environment monitoring, surveillance,structural monitoring, traffic monitoring, and industrial automation.However, the VSNs also raise new challenges. They generate large amount ofdata which require higher processing powers, large bandwidth requirementsand more energy resources but the main constraint is that the VSN nodes arelimited in these resources.This research focuses on the development of a VSN model to track thelarge birds such as Golden Eagle in the sky. The model explores a number ofcamera sensors along with optics such as lens of suitable focal length whichensures a minimum required resolution of a bird, flying at the highestaltitude. The combination of a camera sensor and a lens formulate amonitoring node. The camera node model is used to optimize the placementof the nodes for full coverage of a given area above a required lower altitude.The model also presents the solution to minimize the cost (number of sensornodes) to fully cover a given area between the two required extremes, higherand lower altitudes, in terms of camera sensor, lens focal length, camera nodeplacement and actual number of nodes for sky surveillance.The area covered by a VSN can be increased by increasing the highermonitoring altitude and/or decreasing the lower monitoring altitude.However, it also increases the cost of the VSN. The desirable objective is toincrease the covered area but decrease the cost. This objective is achieved byusing optimization techniques to design a heterogeneous VSN. The core ideais to divide a given monitoring range of altitudes into a number of sub-rangesof altitudes. The sub-ranges of monitoring altitudes are covered by individualsub VSNs, the VSN1 covers the lower sub-range of altitudes, the VSN2 coversthe next higher sub-range of altitudes and so on, such that a minimum cost isused to monitor a given area.To verify the concepts, developed to design the VSN model, and theoptimization techniques to decrease the VSN cost, the measurements areperformed with actual cameras and optics. The laptop machines are used withthe camera nodes as data storage and analysis platforms. The area coverage ismeasured at the desired lower altitude limits of homogeneous as well asheterogeneous VSNs and verified for 100% coverage. Similarly, the minimumresolution is measured at the desired higher altitude limits of homogeneous aswell as heterogeneous VSNs to ensure that the models are able to track thebird at these highest altitudes.
|
|
| 7. |
- Ainegren, Mats, 1963-
(author)
-
The rolling resistances of roller skis and their effects on human performance during treadmill roller skiing
- 2010
-
Licentiate thesis (other academic/artistic)abstract
- Modern ski-treadmills allow cross-country skiers, biathletes and ski-orienteers to test their physical performance in a laboratory environment using classical and freestyle techniques on roller skis. For elite athletes the differences in performance between test occasions are quite small, thus emphasising the importance of knowing the roller skis’ rolling resistance coefficient, µR, in order to allow correct comparisons between the results, as well as providing the opportunity to study work economy between different athletes, test occasions and core techniques.Thus, one of the aims of this thesis was to evaluate how roller skis’ µR is related to warm-up, mass, velocity and inclination of the treadmill. It was also necessary to investigate the methodological variability of the rolling resistance measurement system, RRMS, specially produced for the experiments, with a reproducibility study in order to indicate the validity and reliability of the results.The aim was also to study physiological responses to different µR during roller skiing with freestyle and classical roller skis and techniques on the treadmill as a case in which all measurements were carried out in stationary and comparable conditions.Finally, the aim was also to investigate the work economy of amateurs and female and male junior and senior cross-country skiers during treadmill roller skiing, i.e. as a function of skill, age and gender, including whether differences in body mass causes significant differences in external power per kg due to differences in the roller skis’ µR.The experiments showed that during a warm-up period of 30 minutes, µR decreased to about 60-65% and 70-75% of its initial value for freestyle and classical roller skis respectively. For another 30 minutes of rolling no significant change was found. Simultaneous measurements of roller ski temperature and mR showed that stabilized mR corresponds to a certain running temperature for a given normal force on the roller ski. The study of the influence on mR of normal force, velocity and inclination produced a significant influence of normal force on mR, while different velocities and inclinations of the treadmill only resulted in small changes in mR. The reproducibility study of the RRMS showed no significant differences between paired measurements with either classical or the freestyle roller skis.The study of the effects on physiological variables of ~50% change in µR,showed that during submaximal steady state exercise, external power, oxygen uptake, heart rate and blood lactate were significantly changed, while there were non significant or only small changes to cycle rate, cycle length and ratings of perceived exertion. Incremental maximal tests showed that time to exhaustion was significantly changed and this occurred without a significantly changed maximal power, maximal oxygen uptake, maximal heart rate and blood lactate, and that the influence on ratings of perceived exertion was non significant or small.The final part of the thesis, which focused on work economy, found no significant difference between the four groups of elite competitors, i.e. between the two genders and between the junior and senior elite athletes. It was only the male amateurs who significantly differed among the five studied groups. The study also showed that the external power per kg was significantly different between the two genders due to differences in body mass and mR, i.e. the lighter female testing groups were roller skiing with a relatively heavier rolling resistance coefficient compared to the heavier testing groups of male participants.
|
|
| 8. |
|
|
| 9. |
- Alfredsson, Jon
(author)
-
Performance of Digital Floating-Gate Circuits Operating at Subthreshold Power Supply Voltages
- 2007
-
Licentiate thesis (other academic/artistic)abstract
- All who is involved in electronic design knows that one of the critical issues in today’s electronic is the power consumption. Designers are always looking for new approaches in order to reduce currents while still retain performance. Floating-gate (FGMOS) circuits have previously been shown to be a promising technique to improve speed and still keep the power consumption low when power supply is reduced below subthreshold voltage for the transistors. In this thesis, the goal is to determine how good floating-gate circuits can be compared to conventional static CMOS when the circuits are working in subthreshold. The most interesting performance parameters are speed and power consumption and specifically the Energy-Delay Product (EDP) that is a combination of those two. To get a view over how the performance varies and how good the FGMOS circuits are at their best case, the circuits have been designed and simulated for best case performance. The investigation also includes trade-offs with speed and power consumption for better performance, how to select floating-gate capacitances, how a large circuit fan-in will affect performance and also the influence of different kinds of refresh circuits. The first simulations of the FGMOS circuits in a 0.13 μm process have several interesting results. First of all, in the best case it is shown that FGMOS has potential to achieve up to 260 times in better EDP-performance compared to CMOS at 150 mV power supply. Continuing with simulations of FGMOS capacitances shows that minimum floating-gate capacitance can be as small as 400 fF and more realistic performance shows that EDP is 37 times better for FGMOS (with parasitic capacitances included). Other aspects of FGMOS design have been to look at how refresh circuits will affect performance (semi-floating-gate circuits) and how a larger fan-in will change noise margin and EDP. It turns out that refresh circuits with the same transistor size does not give a noticeable change in performance while an increase of 8 times in size will give between 5 and 10 times wors EDP. When it comes to fan-in the simulations shows that a maximum fan-in of 5 is possible at 250 mV supply and it decrease to 3 when supply voltage is reduced to 150 mV. Finally, it should be kept in mind that tuning the performance of FGMOS circuits with trade-offs and by changing the floating-gate voltages to achieve results like the ones stated above will also always affect the noise margins, NM, of the circuits. As a consequence of this, the NM will sometimes be so close to 1 that a fabricated circuit with that NM may not be as functional as simulations suggests. The probability to design functional FGMOS circuits in subthreshold does not seem to be a problem though.
|
|
| 10. |
- Ambatipudi, Radhika, 1982-
(author)
-
Multilayered Coreless Printed Circuit Board (PCB) Step-down Transformers for High Frequency Switch Mode Power Supplies (SMPS)
- 2011
-
Licentiate thesis (other academic/artistic)abstract
- The Power Supply Unit (PSU) plays a vital role in almost all electronic equipment. The continuous efforts applied to the improvement of semiconductor devices such as MOSFETS, diodes, controllers and MOSFET drivers have led to the increased switching speeds of power supplies. By increasing the switching frequency of the converter, the size of passive elements such as inductors, transformers and capacitors can be reduced. Hence, the high frequency transformer has become the backbone in isolated AC/DC and DC/DC converters. The main features of transformers are to provide isolation for safety purpose, multiple outputs such as in telecom applications, to build step down/step up converters and so on. The core based transformers, when operated at higher frequencies, do have limitations such as core losses which are proportional to the operating frequency. Even though the core materials are available in a few MHz frequency regions, because of the copper losses in the windings of the transformers those which are commercially available were limited from a few hundred kHz to 1MHz. The skin and proximity effects because of induced eddy currents act as major drawbacks while operating these transformers at higher frequencies. Therefore, it is necessary to mitigate these core losses, skin and proximity effects while operating the transformers at very high frequencies. This can be achieved by eliminating the magnetic cores of transformers and by introducing a proper winding structure.A new multi-layered coreless printed circuit board (PCB) step down transformer for power transfer applications has been designed and this maintains the advantages offered by existing core based transformers such as, high voltage gain, high coupling coefficient, sufficient input impedance and high energy efficiency with the assistance of a resonant technique. In addition, different winding structures have been studied and analysed for higher step down ratios in order to reduce copper losses in the windings and to achieve a higher coupling coefficient. The advantage of increasing the layer for the given power transfer application in terms of the coupling coefficient, resistance and energy efficiency has been reported. The maximum energy efficiency of the designed three layered transformers was found to be within the range of 90%-97% for power transfer applications operated in a few MHz frequency regions. The designed multi-layered coreless PCB transformers for given power applications of 8, 15 and 30W show that the volume reduction of approximately 40-90% is possible when compared to its existing core based counterparts. The estimation of EMI emissions from the designed transformers proves that the amount of radiated EMI from a three layered transformer is less than that of the two layered transformer because of the decreased radius for the same amount of inductance.Multi-layered coreless PCB gate drive transformers were designed for signal transfer applications and have successfully driven the double ended topologies such as the half bridge, the two switch flyback converter and resonant converters with low gate drive power consumption of about half a watt. The performance characteristics of these transformers have also been evaluated using the high frequency magnetic material made up of NiZn and operated in the 2-4MHz frequency region.These multi-layered coreless PCB power and signal transformers together with the latest semiconductor switching devices such as SiC and GaN MOSFETs and the SiC schottky diode are an excellent choice for the next generation compact SMPS.
|
|
