| 1. |
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| 2. |
- Akbari, Saaed, et al.
(författare)
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Effect of PCB cracks on thermal cycling reliability of passive microelectronic components with single-grained solder joints
- 2019
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Ingår i: Microelectronics and reliability. - : Elsevier BV. - 0026-2714 .- 1872-941X. ; 93, s. 61-71
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Tidskriftsartikel (refereegranskat)abstract
- Lead-free tin-based solder joints often have a single-grained structure with random orientation and highly anisotropic properties. These alloys are typically stiffer than lead-based solders, hence transfer more stress to printed circuit boards (PCBs) during thermal cycling. This may lead to cracking of the PCB laminate close to the solder joints, which could increase the PCB flexibility, alleviate strain on the solder joints, and thereby enhance the solder fatigue life. If this happens during accelerated thermal cycling it may result in overestimating the lifetime of solder joints in field conditions. In this study, the grain structure of SAC305 solder joints connecting ceramic resistors to PCBs was studied using polarized light microscopy and was found to be mostly single-grained. After thermal cycling, cracks were observed in the PCB under the solder joints. These cracks were likely formed at the early stages of thermal cycling prior to damage initiation in the solder. A finite element model incorporating temperature-dependant anisotropic thermal and mechanical properties of single-grained solder joints is developed to study these observations in detail. The model is able to predict the location of damage initiation in the PCB and the solder joints of ceramic resistors with reasonable accuracy. It also shows that the PCB cracks of even very small lengths may significantly reduce accumulated creep strain and creep work in the solder joints. The proposed model is also able to evaluate the influence of solder anisotropy on damage evolution in the neighbouring (opposite) solder joints of a ceramic resistor.
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| 3. |
- Andersson, Dag, et al.
(författare)
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COSIVU - Compact, smart and reliable drive unit for fully electric vehicles
- 2016
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Ingår i: 2016 Pan Pacific Microelectronics Symposium (Pan Pacific). - : Institute of Electrical and Electronics Engineers Inc.. - 9780988887398
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Konferensbidrag (refereegranskat)abstract
- COSIVU is a three year collaborative research project that ended in September 2015 and which has been funded within the European Green Car Initiative (now the European Green Vehicle Initiative). COSIVU addresses one of the most critical technical parts in fully electrical vehicles (FEV) besides the energy storage system: the mechatronic drive-train unit. The COSIVU project has delivered a new system architecture for multiple wheel drive-trains by a smart, compact and durable single-wheel drive unit with integrated electric motor, full silicon carbide (SiC) power electronics (switches and diodes), a novel control and health monitoring module with wireless communication, and an advanced ultra-compact cooling solution. DfR utilizing FEM simulations ensures first time right solutions. This paper presents the main results including the architecture of the drive train solution as well as the modular design of the inverter based on Inverter Building Blocks, one per phase. Performance tests are presented here for the first time for both the heavy duty commercial vehicle solution performed in a test rig by Volvo, and the tests of the COSIVU solution adapted to a passenger car done by Elaphe.
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| 4. |
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| 5. |
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| 6. |
- Andersson, Dag, et al.
(författare)
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Smart access to small lot manufacturing for systems integration
- 2018
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Ingår i: 2018 Pan Pacific Microelectronics Symposium, Pan Pacific 2018. - 9781944543044 ; , s. 1-9
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Konferensbidrag (refereegranskat)abstract
- The three year EU project SMARTER-SI that ends in January 2018 has tested a new concept for small lot manufacturing for SMEs which we call the Cooperative Foundry Model (CFM). During previous research, all RTOs have completed building blocks, i.e. components or parts of systems which are readily available and characterized by their high Technology Readiness Level (TRL). These building blocks are combined and integrated in so-called Application Experiments (AEs), thereby creating innovative Smart Systems that serve the SMEs' needs. Four pre defined AEs have been presented before [1] and in this paper, six additional AEs will be presented: i) a smart sensor for pneumatic combined clutch and brakes, ii) smart well plates for tissue engineering integrating continuous, non-invasive TEER iii) microclimate sensor for moisture applications, iv) LTCC-Si-Pressure Sensor, v) miniaturized capillary electrophoresis system for bio analysis, and vi) a MEMS sensor module for respiratory applications. Finally, a brief description of ongoing standardization efforts is presented.
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| 7. |
- Andersson, Dag, et al.
(författare)
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SMARTER-SI - Smart access to manufacturing for Systems Integration
- 2017
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Konferensbidrag (refereegranskat)abstract
- The three year EU project SMARTER-SI that started in February 2015 has developed and tested a new production platform for smart systems that offer SMEs and “mid-cap” companies help to manufacture small and medium volumes. The ultimate goal of this project is to test a new concept for small lot production, which we call the Cooperative Foundry Model (CFM). The CFM is tested by combining components or parts of systems (building blocks) already developed by the RTOs involved in the project in so-called Application Experiments (AEs), thereby creating innovative Smart Systems which serve SMEs' product needs. During the first two years, four predefined AEs have been developed that consist of i) a multi-parametric point of care testing (POCT) device, ii) a dew-point measurement system, iii) a CO2 measurement system, and iv) a portable device that can be used to screen water quality.
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| 8. |
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| 9. |
- Andersson, Eric, 1992, et al.
(författare)
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Nondestructive cleaning of the LaAlO3/SrTiO3 surface with ultraviolet light and ozone
- 2016
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Ingår i: Journal of Vacuum Science and Technology B: Nanotechnology and Microelectronics. - : American Vacuum Society. - 2166-2746 .- 2166-2754. ; 34:4
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Tidskriftsartikel (refereegranskat)abstract
- The effect of ultraviolet light produced ozone and irradiation (UV/ozone) cleaning on the surface properties and interface electrical properties of 4 unit cell (uc) LaAlO3/SrTiO3 samples is examined. A standard photolithography process is used to contaminate the samples which are then cleaned in UV/ozone. Atomic force microscopy measurements show that the photoresist contaminated samples can be cleaned efficiently using this method. The surface roughness of the cleaned samples is comparable to that of the as-grown samples. Furthermore, electrical transport measurements show that the mobility decreases and the sheet carrier density increases for the contaminated samples, which also display indications of an onset to the Kondo effect. By removing the contaminants with UV/ozone cleaning, the mobility and sheet carrier density can be partially restored toward the as-grown values. The mobility is increased by about two times from approximate to 1000 cm(2) V-1 s(-1) for the contaminated samples to approximate to 2000 cm(2) V-1 s(-1) for the ozone cleaned ones. (C) 2016 American Vacuum Society.
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| 10. |
- Andersson, Susanne, et al.
(författare)
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Moving with(in) normative firewalls : a dynamic approach to study gendered careers and innovation processes in the truck industry
- 2018
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Konferensbidrag (refereegranskat)abstract
- In this paper we explore how existing work place culture and gendered norms impact on the possibilities to work with so called ”norm-critical” innovation processes in an organisation. Norm-critical reflexivity in the context of innovation processes implies to pay attention to invisible and implicit norms that may result in that certain privileged perspectives is being prevailed (over others) (Balkmar & Lykke 2015). The empirical findings emanates from a two year interactive research project, in which gender researchers in collaboration with participants at Volvo Group, Sweden, have explored the ways that the company can increase its capacity to work with norm-critical perspectives in the innovation process. Volvo is a highly gender segregated organisation. At the same time the trucking industry in itself is highly masculinized in terms of different professions; ranging from truck drivers to sales personnel to technical engineers involved in the design and manufacturing of trucks. In later years the shortage of truck drivers, in combination with more women drivers entering trucking academies and haulage contractors, has led to a questioning of male norms in the transport business. This includes reports of difficult working conditions for female truckers, including how the design of the truck itself takes the male body as the implicit norm, to the assumption that it is a man that is the presumed driver of trucks.This paper focus on the part of the project that seeks to better understand how existing work-place culture and norms structure who is considered the ideal employee (Acker 1992) and its implications for innovation. This includes studying its impacts on both the possibility for different categories of employees to take part in the innovation work on equal terms, and the ability to reflect upon the impact of implicit norms in the innovation process itself. In total, 17 semi-structured interviews were conducted with co-workers and managers (13 women and 5 men). The main questions concerned whether there existed ideals that formed implicit ”codes” (Bendl and Schmidt 2010) in the organization and its impact on ideas of preferred professional qualifications, behaviors, personal qualities and its links to career possibilities and innovation. The underlying theoretical assumption is that gender is a fundamental element of organisational structure and work life; “present in [its] processes, practices, images and ideologies, and distribution of power” (Acker 1992, p. 567). The way that gender plays out in the daily life in a workplace is understood as not being a static barrier prohibiting women in general, rather, it is considered fluid, relational and may vary depending on the context (Meyerson & Fletcher 2001, Bendl and Schmidt 2010). It is argued that the concept ”fire wall” (Bendl and Schmidt 2010 ), offers a fruitful way to highlight the elasticity and permeability that we believe characterize the forms of discrimination, inclusion and exclusion that takes place in these processes.ReferencesAcker, J. 1992. Gendering Organisational Theory. In Mills, A. and Tancered, P. (eds.). Gendering Organisational Analysis. London: SAGE.Acker, J. 2006. Inequality Regimes: Gender, Class, and Race in Organisations. Gender and Society 20(4):441-464.Balkmar, D. & Lykke, N. 2015. Developing disruptive norm-critical innovation at Volvo: FINAL REPORT. Linköping: Tema Genus Report Series No. 23: 2015.Bendl, R. & Schmidt. 2012. From 'Glass Ceilings' to 'Firewalls' - Different Metaphors for Describing Discrimination. Gender, Work and Organization. Vol. 17. No 5:612-635.Meyerson, D. & Fletcher J.K. 2001. A Modest Manifesto for Shattering the Glass Ceiling. Boston: Harvard Business Review.
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| 11. |
- Andersson, Åsa, et al.
(författare)
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Översyn av förordning om miljökvalitetsnormer för fisk- och musselvatten : Redovisning av regeringsuppdrag med Havs- och vattenmyndighetens analys av normerna och förslag till ändrad lagstiftning
- 2016
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Regeringen gav genom ett beslut den 22 oktober 2015 Havs- och vattenmyndigheten i uppdrag att göra en översyn av förordningen (2001:554) om miljökvalitetsnormer för fisk- och musselvatten (fisk- och musselvattenförordningen). Behovet av att göra denna översyn har framförts av Havs- och vattenmyndigheten, Naturvårdsverket och Länsstyrelsen i Västra Götalands län. I rapporten görs en översyn av miljökvalitetsnormerna i förordningen (2001:554) om miljökvalitetsnormer för fisk- och musselvatten och en bedömning av om det finns normer som bör ändras, tas bort eller om samma skyddsnivå kan uppnås på annat sätt. Havs- och vattenmyndigheten föreslår att fisk- och musselvattenförordningen upphävs. Som en följd av detta behöver ett antal föreskrifter upphävas eller ändras. Därutöver behöver viss vägledning tas fram för att täcka återstående skyddsbehov.Det är svårt att få en överblick av i vilken utsträckning fisk- och musselvattenförordningen har påverkat den övervakning som bedrivs och hur mycket övervakning som bedrivs enbart utifrån förordningens krav. Havs- och vattenmyndighetens bedömning är dock att ett upphävande av förordningen inte kommer att påverka den övervakning som utförs på ett betydande sätt. Konsekvensutredningen visar att fisk- och musselvattenförordningen kan upphävas och att detta medför i huvudsak positiva effekter för såväl miljön som berörda myndigheter och verksamhetsutövare.
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| 12. |
- Bremer, Hanna, et al.
(författare)
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ILF2 and ILF3 are autoantigens in canine systemic autoimmune disease
- 2018
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Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Dogs can spontaneously develop complex systemic autoimmune disorders, with similarities to human autoimmune disease. Autoantibodies directed at self-antigens are a key feature of these autoimmune diseases. Here we report the identification of interleukin enhancer-binding factors 2 and 3 (ILF2 and ILF3) as autoantigens in canine immune-mediated rheumatic disease. The ILF2 autoantibodies were discovered in a small, selected canine cohort through the use of human protein arrays; a method not previously described in dogs. Subsequently, ILF3 autoantibodies were also identified in the same cohort. The results were validated with an independent method in a larger cohort of dogs. ILF2 and ILF3 autoantibodies were found exclusively, and at a high frequency, in dogs that showed a speckled pattern of antinuclear antibodies on immunofluorescence. ILF2 and ILF3 autoantibodies were also found at low frequency in human patients with SLE and Sjogren's syndrome. These autoantibodies have the potential to be used as diagnostic biomarkers for canine, and possibly also human, autoimmune disease.
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| 13. |
- Brinkfeldt, Klas, et al.
(författare)
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Design and Fabrication of a SiC-Based Power Module with Double-Sided Cooling for Automotive Applications
- 2016
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Ingår i: Lecture Notes in Mobility. - Cham : Springer International Publishing. - 2196-5544 .- 2196-5552. ; , s. 157-171, s. 157-172
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The electrification of drive trains combined with special requirements of the automotive and heavy construction equipment applications drives the development of small, highly integrated and reliable power inverters. To minimize the volume and increase the reliability of the power switching devices a module consisting of SiC devices with double sided cooling capability has been developed. There are several benefits related to cooling the power devices on both sides. The major improvement is the ability to increase the power density, and thereby reduce the number of active switching devices required which in turn reduces costs. Other expected benefits of more efficient cooling are reductions in volume and mass per power ratio. Alternatively, improved reliability margins due to lower temperature swings during operation are can be expected. Removing the wire bonds on the top side of the devices is expected to improve the reliability regardless, since wire bonds are known to be one of the main limitations in power switching devices. In addition, it is possible to design the package with substantially lower inductance, which can allow faster switching of the devices. In this paper the design, simulations and fabrication process of a double sided SiC-based power module are presented.
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| 14. |
- Brinkfeldt, Klas, et al.
(författare)
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Failure mechanism assessment of TO-247 packaged SiC power devices
- 2018
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Ingår i: ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems, InterPACK 2018. - 9780791851920
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Konferensbidrag (refereegranskat)abstract
- As the automotive industry shifts towards the electrification of drive trains, the efficiency of power electronics becomes more important. The use of silicon carbide (SiC) devices in power electronics has shown several benefits in efficiency, blocking voltage and high temperature operation. In addition, the ability of SiC to operate at higher frequencies due to lower switching losses can result in reduced weight and volume of the system, which also are important factors in vehicles. However, the reliability of packaged SiC devices is not yet fully assessed. Previous work has predicted that the different material properties of SiC compared to Si could have a large influence on the failure mechanisms and reliability. For example, the much higher elastic modulus of SiC compared to Si could increase strain on neighboring materials during power cycling. In this work, the failure mechanisms of packaged Si- and SiC-based power devices have been investigated following power cycling tests. The packaged devices were actively cycled in 4.5 s heating and 20 s cooling at ΔT = 60 - 80 K. A failure analysis using micro-focus X-ray and scanning acoustic microscopy (SAM) was carried out in order to determine the most important failure mechanisms. The results of the analysis indicate that the dominant failure mechanism is wire bond liftoff at the device chip for all of the SiC-based devices. Further analysis is required to determine the exact failure mechanisms of the analyzed Si-based devices. In addition, the SiC-based devices failed before the Si-based devices, which could be a result of the different properties of the SiC material.
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| 15. |
- Brinkfeldt, Klas, et al.
(författare)
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Feasibility of PCB-integrated vibration sensors for condition monitoring of electronic systems
- 2018
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Ingår i: ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems, InterPACK 2018. - 9780791851920
-
Konferensbidrag (refereegranskat)abstract
- The increasing complexity of electronics in systems used in safety critical applications, such as for example self-driving vehicles requires new methods to assure the hardware reliability of the electronic assemblies. Prognostics and Health Management (PHM) that uses a combination of data-driven and Physics-of-Failure models is a promising approach to avoid unexpected failures in the field. However, to enable PHM based partly on Physics-of-Failure models, sensor data that measures the relevant environment loads to which the electronics is subjected during its mission life are required. In this work, the feasibility to manufacture and use integrated sensors in the inner layers of a printed circuit board (PCB) as mission load indicators measuring impacts and vibrations has been investigated. A four-layered PCB was designed in which piezoelectric sensors based on polyvinylidenefluoride-co-trifluoroethylene (PVDF-TrFE) were printed on one of the laminate layers before the lamination process. Manufacturing of the PCB was followed by the assembly of components consisting of BGAs and QFN packages in a standard production reflow soldering process. Tests to ensure that the functionality of the sensor material was unaffected by the soldering process were performed. Results showed a yield of approximately 30 % of the sensors after the reflow soldering process. The yield was also dependent on sensor placement and possibly shape. Optimization of the sensor design and placement is expected to bring the yield to 50 % or better. The sensors responded as expected to impact tests. Delamination areas were present in the test PCBs, which requires further investigation. The delamination does not seem to be due to the presence of embedded sensors alone but rather the result of a combination of several factors. The conclusion of this work is that it is feasible to embed piezoelectric sensors in the layers of a PCB.
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| 16. |
- Brinkfeldt, Klas, et al.
(författare)
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Feasibility of Printed Circuit Board-Integrated Vibration Sensors for Condition Monitoring of Electronic Systems
- 2019
-
Ingår i: Journal of Electronic Packaging. - : American Society of Mechanical Engineers (ASME). - 1043-7398 .- 1528-9044. ; 141:3
-
Tidskriftsartikel (refereegranskat)abstract
- The increasing complexity of electronics in systems used in safety critical applications, such as self-driving vehicles, requires new methods to assure the hardware reliability of the electronic assemblies. Prognostics and health management (PHM) that uses a combination of data-driven and physics-of-failure models is a promising approach to avoid unexpected failures in the field. However, to enable PHM based partly on physics-of-failure models, sensor data that measure the relevant environment loads to which the electronics are subjected during its mission life are required. In this work, the feasibility to manufacture and use integrated sensors in the inner layers of a printed circuit board (PCB) as mission load indicators measuring impacts and vibrations has been investigated. A four-layered PCB was designed in which piezoelectric sensors based on polyvinylidenefluoride-co-trifluoroethylene (PVDF-TrFE) were printed on one of the laminate layers before the lamination process. Manufacturing of the PCB was followed by the assembly of components consisting of ball grid arrays (BGAs) and quad flat no-leads (QFN) packages in a standard production reflow soldering process. Tests to ensure that the functionality of the sensor material was unaffected by the soldering process were performed. Results showed a yield of approximately 30% of the sensors after the reflow soldering process. The yield was also dependent on sensor placement and possibly shape. Optimization of the sensor design and placement is expected to bring the yield to 50% or better. The sensors responded as expected to impact tests. Delamination areas were present in the test PCBs, which requires further investigation. The delamination does not seem to be due to the presence of embedded sensors alone but rather the result of a combination of several factors. The conclusion of this work is that it is feasible to embed piezoelectric sensors in the layers of a PCB.
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| 17. |
- Brinkfeldt, Klas, et al.
(författare)
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Model verification of heat exchangers in a flow test rig
- 2015
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Ingår i: 2015 16th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems, EuroSimE 2015. - : Institute of Electrical and Electronics Engineers Inc.. - 9781479999507 ; , s. 7103135-
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Konferensbidrag (refereegranskat)abstract
- In power electronics, more efficient removal of heat from the junction of power devices leads to a higher power rating per die, which in turn leads to fewer die and reduced system volume. Since temperature is a main driver in expected failure modes an increase in cooling capability can also enhance margins of the device reliability. Previously, CFD simulations of two novel heat exchanger designs that will be used in a power module with double sided cooling have been reported on. The heat exchangers are fabricated by direct 3D manufacturing of copper structures, which allows almost complete freedom in geometric design. Two novel geometries of heat exchanger cooling structures have previously been modeled in terms of thermal performance and expected pressure drop. A flow rig has been designed and calibrated to measure thermal performance and pressure drops of these heat sinks. For calibration purposes, measurements of the thermal response of wave structured and unstructured heat sinks are reported here. The results show that, as expected, the heat sink temperatures are lower for all flow rates in the wavestructured geometry. A thermal CFO model accurately predicts the behavior of the temperature difference between inlet and outlet versus flow rate, but predicts higher absolute temperature values. It was also found that the model underestimates the pressure drop over the tested heat sillies. The pressure drop across a novel pine cone geometry heat sink fabricated by additive manufacturing methods was also measured. Comparisons to a reduced model, which neglects everything before the inlet and after the outlet of the tested device, showed that the behavior of this pine structured heat sink was not predicted correctly. The pressure drop increased more rapidly with flow rates in the model than in the measurements. The main source of error in the measurements and simulations comes from a lack of thermal loading. Future work to improve the flow rig includes possibilities to increase the temperature loading at the bottom of the heat sink under test.
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| 18. |
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| 19. |
- Brinkfeldt, Klas, et al.
(författare)
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Thermal Simulations and Experimental Verification of Power Modules Designed for Double Sided Cooling
- 2016
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Ingår i: Electronic Components and Technology. - : Institute of Electrical and Electronics Engineers Inc.. - 0569-5503. ; , s. 1415-1422
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Tidskriftsartikel (refereegranskat)abstract
- Cooling power modules on both sides of the active switching devices reduces the operational junction temperature compared to conventional single sided cooling. In this work, thermal simulations of power modules based on single sided cooling concepts are compared with double sided cooling counterparts. Expected junction temperatures, maximum temperatures and maximum current capability is analyzed. In addition, experimental verification in the form of comparisons with thermal characterization tests for both single-And double sided power modules based on SiC bipolar junction transistors is presented. Results from simulations show that cooling of both sides of the active switching devices can reduce the thermal resistance by more than 40 percent. This number depends on the heat transfer coefficient. From one example, simulating a worst case stall condition of the electric machine, the use of double sided cooling reduces the maximum junction temperature from 167 °C to 106 °C at a load current of 300 A using a heat transfer coefficient of 4 kW/m2K and 4 kHz switching frequency. Furthermore, the temperature decreases to 97°C if AlN-based DBC substrates are used instead of alumina DBCs. Results from the experimental comparison between double-And single sided cooling showed that the maximum temperature for a load current range of 15 A to 50 A was reduced by 18 percent to 55 percent by using double sided cooling. At a device temperature of 60 °C, the increased thermal capability of the double sided version allowed for a 20 A higher load current, which corresponded to operation under 50 percent higher power losses. Double sided cooling also increased the maximum current capability through a single SiC BJT by more than 20 percent beyond the maximum current capability through the single sided cooling version.
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| 20. |
- Brinkfeldt, Klas, et al.
(författare)
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Thermo-Mechanical Simulations of SiC Power Modules with Single and Double Sided Cooling
- 2015
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Ingår i: 16th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems (EuroSimE), 2015. - : Institute of Electrical and Electronics Engineers Inc.. - 9781479999491 - 9781479999507 ; , s. 1 - 7
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Konferensbidrag (refereegranskat)abstract
- Effectively removing dissipated heat from the switching devices enables a higher current carrying capability per chip area ratio, thus leading to smaller or fewer devices for a given power requirement specification. Further, the use of SiC based devices has proven to increase the efficiency of the system thereby reducing the dissipated heat. Thermal models have been used to compare SiC power modules. Single and double sided cooling have been simulated. The simulated maximum temperatures were 141 °C for the single sided version and 119.7 °C for the double sided version. In addition, the reliability of a single sided module and thermally induced plastic strains of a double sided module have been investigated. A local model of the wire bond interface to the transistor metallization shows a 30/00 maximum increase in plastic strain during the power cycle. Simulations of the creep strain rates in the die attach solder layer for a power cycling loads also shows a 30/00 increase in creep strain per cycle.
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| 21. |
- Creed, Irena F., et al.
(författare)
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Global change-driven effects on dissolved organic matter composition : Implications for food webs of northern lakes
- 2018
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 24:8, s. 3692-3714
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Forskningsöversikt (refereegranskat)abstract
- Northern ecosystems are experiencing some of the most dramatic impacts of global change on Earth. Rising temperatures, hydrological intensification, changes in atmospheric acid deposition and associated acidification recovery, and changes in vegetative cover are resulting in fundamental changes in terrestrial-aquatic biogeochemical linkages. The effects of global change are readily observed in alterations in the supply of dissolved organic matter (DOM)-the messenger between terrestrial and lake ecosystems-with potentially profound effects on the structure and function of lakes. Northern terrestrial ecosystems contain substantial stores of organic matter and filter or funnel DOM, affecting the timing and magnitude of DOM delivery to surface waters. This terrestrial DOM is processed in streams, rivers, and lakes, ultimately shifting its composition, stoichiometry, and bioavailability. Here, we explore the potential consequences of these global change-driven effects for lake food webs at northern latitudes. Notably, we provide evidence that increased allochthonous DOM supply to lakes is overwhelming increased autochthonous DOM supply that potentially results from earlier ice-out and a longer growing season. Furthermore, we assess the potential implications of this shift for the nutritional quality of autotrophs in terms of their stoichiometry, fatty acid composition, toxin production, and methylmercury concentration, and therefore, contaminant transfer through the food web. We conclude that global change in northern regions leads not only to reduced primary productivity but also to nutritionally poorer lake food webs, with discernible consequences for the trophic web to fish and humans.
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| 22. |
- Edwards, Michael, 1986, et al.
(författare)
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The shear strength of nano-Ag sintered joints and the use of Ag interconnects in the design and manufacture of SiGe-based thermo-electric modules
- 2015
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Ingår i: Microelectronics and Reliability. - : Elsevier BV. - 0026-2714 .- 1872-941X. ; 55:5, s. 722-732
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Tidskriftsartikel (refereegranskat)abstract
- Thermo-electric modules (TEMs) can be used to convert heat into electricity by utilizing the Seeback effect. It is now possible to buy BiTe thermo-electric modules that can operate up to temperatures of around 300 °C. However, many applications, such as the harvesting of excess gas turbine heat, may occur at higher temperatures. Therefore, new materials and manufacturing processes need to be developed to produce packaged TEMs that can operate at a maximum operating temperature of 650 °C. Two critical areas in the manufacture of a SiGe TEM are the choice and strength of materials used to both sintered joint the TE material to the rest of the module and the metal used for the interconnects. The interconnection material needs to be sufficiently strong to withstand large temperature fluctuations while maintaining a low contact resistance, as well as being compatible with the nano-Ag sintered joint. Shear force tests of the sintered thermo electrical leg material showed that the joints are brittle when sintered to W metallized AlN substrates are used and ductile fracture behavior when sintered to Cu metallized AlN substrates using the NanoTach K nano silver paste. Almost all of the joints were found to be brittle when using the NachTach X nano silver paste. Shear testing of the sintered joints showed that the X paste joints were variable in strength and stiffness, having a typical Young's modulus between 10 and 100 MPa at room temperature. The K paste joints were stiffer, but had a similar strength as compared to the X paste joints.
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| 23. |
- Farias, Fabiana H. G., et al.
(författare)
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A rare regulatory variant in the MEF2D gene affects gene regulation and splicing and is associated with a SLE sub-phenotype in Swedish cohorts
- 2019
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Ingår i: European Journal of Human Genetics. - : Springer Science and Business Media LLC. - 1018-4813 .- 1476-5438. ; 27, s. 432-441
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Tidskriftsartikel (refereegranskat)abstract
- Systemic lupus erythematosus (SLE) is an autoimmune disorder with heterogeneous clinical presentation and complex etiology involving the interplay between genetic, epigenetic, environmental and hormonal factors. Many common SNPs identified by genome wide-association studies (GWAS) explain only a small part of the disease heritability suggesting the contribution from rare genetic variants, undetectable in GWAS, and complex epistatic interactions. Using targeted re-sequencing of coding and conserved regulatory regions within and around 215 candidate genes selected on the basis of their known role in autoimmunity and genes associated with canine immune-mediated diseases, we identified a rare regulatory variant rs200395694:G > T located in intron 4 of the MEF2D gene encoding the myocyte-specific enhancer factor 2D transcription factor and associated with SLE in Swedish cohorts (504 SLE patients and 839 healthy controls, p = 0.014, CI = 1.1-10). Fisher's exact test revealed an association between the genetic variant and a triad of disease manifestations including Raynaud, anti-U1-ribonucleoprotein (anti-RNP), and anti-Smith (anti-Sm) antibodies (p = 0.00037) among the patients. The DNA-binding activity of the allele was further studied by EMSA, reporter assays, and minigenes. The region has properties of an active cell-specific enhancer, differentially affected by the alleles of rs200395694:G > T. In addition, the risk allele exerts an inhibitory effect on the splicing of the alternative tissue-specific isoform, and thus may modify the target gene set regulated by this isoform. These findings emphasize the potential of dissecting traits of complex diseases and correlating them with rare risk alleles with strong biological effects.
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| 24. |
- Forstner, O., et al.
(författare)
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The ILIAS project for selective isobar suppression by laser photodetachment
- 2015
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Ingår i: Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms. - : Elsevier BV. - 0168-583X. ; 361, s. 217-221
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Tidskriftsartikel (refereegranskat)abstract
- Laser photodetachment is the process when the extra electron of a negative ion is removed by means of laser radiation. This can happen only if the photon energy is larger than the electron affinity of the ion. The process can be used in mass spectrometry to selectively suppress unwanted isobars, provided that the electron affinity of the unwanted isobar is lower than that of the isobar under investigation.At the Ion Laser InterAction Setup (ILIAS) at the University of Vienna laser photodetachment of negative atomic and molecular ions is studied and its applicability for selective isobar suppression in accelerator mass spectrometry (AMS) is evaluated. The setup provides mass separated beams of negative ions with energies up to 30 keV. Negative ions are produced in a Middleton type cesium sputter ion source, mass selected and overlapped with a strong continuous wave laser beam. In order to extend the interaction time of ions and laser, the ion beam is decelerated to thermal energies in a gas-filled radio frequency quadrupole cooler. For an appropriate choice of the photon energy, unwanted isobars are neutralized while the isobar of interest is unaffected and remains negatively charged.A description of the ILIAS setup and results from the commissioning phase of the RFQ cooler are presented. Up to 8% ion beam transmission could be achieved after a recent redesign of the extraction system. Furthermore first results of photodetachment experiments of 63Cu− within the RFQ cooler are presented.
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| 25. |
- Ivansen, Lars, 1965, et al.
(författare)
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Identifying Barriers to Agile Technology Roadmapping
- 2018
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Ingår i: Systems Engineering in Context. - Cham : Springer International Publishing. ; , s. 371-382
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Konferensbidrag (refereegranskat)abstract
- This paper presents findings from two case studies relating to technology development and barriers identified. The purpose of the paper is to identify a solid baseline from which a combined technology and product roadmap can be defined, as such the first step is to rigorously describe and analyze the underlying barriers and challenges through exploring two historic cases. The project has in part been carried out as a master thesis project by the main author and later on as a PhD student project. The project identifies several issues relating to technology maturity assessments, (internal and external readiness) as well as problems relating to technology complexity.
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| 26. |
- Karlsson, Helene, et al.
(författare)
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Quality assurance of encapsulation architecture, including subsequent washing process for permanently mounted wearable sensors
- 2018
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Ingår i: 2018 IMAPS Nordic Conference on Microelectronics Packaging (NordPac). - 9789526815053 ; , s. 14-23
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Konferensbidrag (refereegranskat)abstract
- The overall objective of the project wearITmed, Wearable sensors in smart textiles, is to develop a novel wearable sensor system demonstrator. This sensor system aims to monitor symptoms of neurological disorders such as epilepsy, Parkinson’s disease and stroke. The wearable sensor system demonstrator, including both integrated gyros/accelerometers and textile sensors, is useful for the evaluation of clinically relevant movement patterns and other physiological parameters, and further to establish disease discriminating and treatment responsive objective variables. The work presented in this paper is focused on ensuring that the wearable sensor system can be cleaned and washed without first removing the electronics. The work includes three main areas; the adhesion and architecture, the molding and finally the washing test performance. Standard wettability and peel tests (Volvo Standard STD 185–0001) were performed on standard test board IPC-B-5 and IPC-9202 test vehicle for selecting the best adhesive and encapsulation materials in form of an epoxy (Epotek 302–3M) and a medical approved silicone (Nusil MED-6019). The molded components were washtested (Standard SS-EN ISO 6330:2012) followed by testing of the electrical resistance (Standard IPC-9202). As a result a total of 22 garments were produced with four individually mounted boards in each garment. The tests showed that the wearable sensors passed the washing tests and were still functional after 10 repeated washing cycles without any change or degradation in resistance or sign of electrical failure. The wearable electronics therefore meets the requirements of being simultaneously resistant to; water, temperature (40 °C), chemical detergents and dynamic forces.
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| 27. |
- Kroupa, A., et al.
(författare)
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Lead-Free Soldering : Environmentally Friendly Electronics
- 2015
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Ingår i: Green and Sustainable Manufacturing of Advanced Materials. - : Elsevier. - 9780124114975 ; , s. 101-134
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The substitution of lead in the electronics industry is one of the key issues in the current drive toward ecological manufacturing. This chapter is aimed at giving an overview of requirements, current situation, problems, and possible development of lead-free soldering and other environmentally friendly joining technologies. It starts with the overview of existing EU regulations and directives. The current situation in the lead-free soldering field is mapped here and a review of the literature, including a patent search, reveals systems and technologies that are at the focus of research effort. New approaches that employ the use of theoretical modeling in the development of new materials is briefly discussed in this chapter.The final part shows the difficulties that the industry faces when implementing new materials into production. The task of this part is to summarize the likely impacts of the phasing out of lead-containing solders for industry, especially small- and medium-sized enterprises.
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| 28. |
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| 29. |
- Lövberg, Andreas, et al.
(författare)
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On the formation and propagation of laminate cracks and their influence on the fatigue lives of solder joints
- 2018
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Ingår i: 2018 19th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems, EuroSimE 2018. - 9781538623596 ; , s. 1-13
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Konferensbidrag (refereegranskat)abstract
- Lead-free solder joints have been shown to increase the risk for crack formation in the PCB laminate under the solder pads. As such cracks propagate during thermal cycling, they decrease the strain imposed on the solderjoint by acting as strain relief. In accelerated thermal cycling, these joints have been found to remain virtually undamaged even after a very high number of cycles. If these cracks do not form or propagate to the same extent under milder cycling conditions, typical of service conditions, it may lead to an overestimation of the fatigue life of the solder joints in accelerated testing. In this work, the extent of strain relief and the influence of grain orientations on the initiation and propagation of these cracks are investigated through FE-modelling and compared to what has been experimentally observed for cross-sections of solder joints moulded in epoxy resin with added fluorescent agent and inspected using UV-light and electron backscatter diffraction. Due to the strong anisotropy of lead-free solder joints, the stress transferred to the laminate will vary significantly depending on grain orientation. The presence of these laminate cracks adds another layer of uncertainty to the already complex SnAgCu system, where the strong effects of anisotropy, the continuously evolving secondary precipitate coarsening and its interaction with the recrystallisation process govern the damage evolution. If these effects are not properly accounted for, the interpretation of thermal cycling or modelling and simulation results may be strongly misleading.
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| 30. |
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| 31. |
- Martschini, M., et al.
(författare)
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Selective laser photodetachment of intense atomic and molecular negative ion beams with the ILIAS RFQ ion beam cooler
- 2017
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Ingår i: International Journal of Mass Spectrometry. - : Elsevier BV. - 1387-3806. ; 415, s. 9-17
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Tidskriftsartikel (refereegranskat)abstract
- The Ion Laser InterAction Setup (ILIAS) project at the University of Vienna aims at the exploration of negative ion beam filtering by selective laser photodetachment for applications in accelerator mass spectrometry (AMS). A gas-filled radio frequency quadrupole (RFQ) is used to decelerate and cool negative atomic and molecular ion beams with intensities of up to several-hundred nA, and overlap them collinearly with a continuous wave (cw) laser beam. Ion-laser interaction times ranging from 500 mu s to several ms allow for highly efficient, selective photodetachment depletion of disturbing ion species within these beams. The elemental selectivity of this technique is based on the differences in electron affinities, and therefore does not depend on relative differences in atomic numbers. It may therefore provide sufficient isobar suppression for new trace isotopes, which are not accessible with existing AMS techniques. The ILIAS RFQ cooler was characterized at a purpose-built test bench with respect to ion beam transmission, ion cooling capabilities and ion residence times as a function of injected ion current to assess its suitability for future AMS use. A Cu-63(-) test beam of 600 nA was photodetached with more than 99.999% efficiency with a 532 nm laser at 10.8 W power. At the same time, ions of interest having electron affinities higher than the photon energy passed the cooler unaffected. Total ion losses were thus found to be below 50% of the sputter source output. Finally, first photodetachment experiments in connection with Al-26 detection demonstrated selective isobar suppression of MgO- vs. AlO- by more than 4 orders of magnitude. Currently, the RFQ cooler is moved to a new injector beamline at the Vienna Environmental Research Accelerator (VERA) for first applications of this novel technique at a state-of-the-art AMS facility. (C) 2016 Elsevier B.V. All rights reserved.
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| 32. |
- Mjörnstedt, Lars, 1956, et al.
(författare)
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Renal function three years after early conversion from a calcineurin inhibitor to everolimus : results from a randomized trial in kidney transplantation
- 2015
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Ingår i: Transplant International. - : Frontiers Media SA. - 0934-0874 .- 1432-2277. ; 28:1, s. 42-51
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Tidskriftsartikel (refereegranskat)abstract
- In a 36-month, open-label, multicenter trial, 202 kidney transplant recipients were randomized at week 7 post-transplant to convert to everolimus or remain on cyclosporine: 182 were analyzed to month 36 (92 everolimus, 90 controls). Mean (SD) change in measured GFR (mGFR) from randomization to month 36 was 1.3 (14.0)ml/min with everolimus versus -1.7 (15.4)ml/min in controls (P=0.210). In patients who remained on treatment, mean mGFR improved from randomization to month 36 by 7.9 (11.5)ml/min with everolimus (n=37) but decreased by 1.4 (14.7)ml/min in controls (n=62) (P=0.001). During months 12-36, death-censored graft survival was 100%, patient survival was 98.9% and 96.7% in the everolimus and control groups, respectively, and 13.0% and 11.1% of everolimus and control patients, respectively, experienced mild biopsy-proven acute rejection (BPAR). Protocol biopsies in a limited number of on-treatment patients showed similar interstitial fibrosis progression. Donor-specific antibodies were present at month 36 in 6.3% (2/32) and 18.0% (9/50) of on-treatment everolimus and control patients with available data (P=0.281). During months 12-36, adverse events were comparable, but discontinuation was more frequent with everolimus (33.7% vs. 10.0%). Conversion from cyclosporine to everolimus at 7weeks post-transplant was associated with a significant benefit in renal function at 3years when everolimus was continued.
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| 33. |
- Nilsson, Charlotta, et al.
(författare)
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Outcomes of women with gestational diabetes mellitus in Sweden.
- 2015
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Ingår i: European Journal of Obstetrics, Gynecology, and Reproductive Biology. - : Elsevier BV. - 0301-2115. ; 193, s. 132-135
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Tidskriftsartikel (refereegranskat)abstract
- The number of women with gestational diabetes mellitus (GDM) during pregnancy is increasing around the world and in our region in the south Sweden 1.2% of all pregnant women received the GDM diagnosis in the 90s and now it is about 2.2%. The aim of this study was to compare women with GDM 1995-99 against women with GDM 2012-13 regarding eventual differences in demographics and pregnancy outcome.
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| 34. |
- Tersmeden, Fredrik, et al.
(författare)
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350 näsor under 350 år
- 2018
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Bok (populärvet., debatt m.m.)abstract
- Lättsamt biografiskt översiktsverk med korta personbeskrivningar i ord och bild av dels de 190 personer som t o m 2017 införlivats i Akademiska Föreningens Nasotek, dels ytterligare 160 lundaanknutna historiska personer.
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| 35. |
- Trabaldo, Edoardo, 1990, et al.
(författare)
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Grooved Dayem Nanobridges as Building Blocks of High-Performance YBa2Cu3O7−δ SQUID Magnetometers
- 2019
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 19:3, s. 1902-1907
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Tidskriftsartikel (refereegranskat)abstract
- We present noise measurements performed on a YBa 2 Cu 3 O 7-δ nanoscale weak-link-based magnetometer consisting of a superconducting quantum interference device (SQUID) galvanically coupled to a 3.5 × 3.5 mm 2 pick-up loop, reaching white flux noise levels and magnetic noise levels as low as 6μÎ0/Hz and 100 fT/Hz at T = 77 K, respectively. The low noise is achieved by introducing grooved Dayem bridges (GDBs), a new concept of a weak link. A fabrication technique has been developed for the realization of nanoscale grooved bridges, which substitutes standard Dayem bridge weak links. The introduction of these novel key blocks reduces the parasitic inductance of the weak links and increases the differential resistance of the SQUIDs. This greatly improves the device performance, thus resulting in a reduction of the white noise.
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| 36. |
- Trabaldo, Edoardo, 1990, et al.
(författare)
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SQUID magnetometer based on Grooved Dayem nanobridges and a flux transformer
- 2019
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Ingår i: ISEC 2019 - International Superconductive Electronics Conference.
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Konferensbidrag (refereegranskat)abstract
- We report noise measurements performed on a SQUID magnetometer implementing Grooved Dayem nanobridge of YBCO as weak-links. The SQUID shows magnetic flux noise as low as 10μΦ 0}/Hz0.5. The magnetometer is realized by coupling the SQUID to a flux transformer with a two-level coupling scheme using a flip-chip approach. This improves the effective area of the SQUID and result in a magnetic field noise of 50fT/Hz0.5atT=77K.
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| 37. |
- Wedelin, Dag, 1964, et al.
(författare)
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Investigating and developing engineering students’ mathematical modelling and problem-solving skills
- 2015
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Ingår i: European Journal of Engineering Education. - : Informa UK Limited. - 0304-3797 .- 1469-5898. ; 40:5, s. 557-572
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Tidskriftsartikel (refereegranskat)abstract
- How do engineering students approach mathematical modelling problems and how can they learn to deal with such problems? In the context of a course in mathematical modelling and problem solving, and using a qualitative case study approach, we found that the students had little prior experience of mathematical modelling. They were also inexperienced problem solvers, unaware of the importance of understanding the problem and exploring alternatives, and impeded by inappropriate beliefs, attitudes and expectations. Important impacts of the course belong to the metacognitive domain. The nature of the problems, the supervision and the follow-up lectures were emphasised as contributing to the impacts of the course, where students show major development. We discuss these empirical results in relation to a framework for mathematical thinking and the notion of cognitive apprenticeship. Based on the results, we argue that this kind of teaching should be considered in the education of all engineers.
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| 38. |
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| 39. |
- Ågerstrand, Marlene, et al.
(författare)
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A call for action : Improve reporting of research studies to increase the scientific basis for regulatory decision-making
- 2018
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Ingår i: Journal of Applied Toxicology. - : Wiley. - 0260-437X .- 1099-1263. ; 38:5, s. 783-785
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Tidskriftsartikel (refereegranskat)abstract
- This is a call for action to scientific journals to introduce reporting requirements for toxicity and ecotoxicity studies. Such reporting requirements will support the use of peer-reviewed research studies in regulatory decision-making. Moreover, this could improve the reliability and reproducibility of published studies in general and make better use of the resources spent in research.
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