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1.
  • Andersson, Mathias H, et al. (författare)
  • A framework for regulating underwater noise during pile driving
  • 2017
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • Pile driving is a common technique used during the construction of bridges, offshore wind power, and underwater infrastructure or shoreline structures. It is the process by which a foundation, beam or pole is hammered or vibrated down into the bottom, which can generate extremely loud noise that propagates throughout the surrounding water and sediment. The noise can reach such high levels that marine animals are at risk of disturbance, injury or even death.Sweden currently lacks established thresholds stating the level at which underwater noise potentially disturbs or injures marine animals. Hence, there are no guidance values for allowable underwater noise levels from noiseproducing activities to avoid serious environmental impacts. Several countries in Europe have defined thresholds for when underwater noise can result in severe negative environmental impacts as well as standards for measuring, analysing and reporting underwater noise levels.The purpose of this study is to review the scientific literature on underwater noise from pile driving and its effects on marine life. The study aims to define the noise levels that can cause injury and other negative effects and, on this basis, recommend noise levels that can be used to establish guidance values for regulating underwater noise for Swedish waters and species. The study presents examples of the factors that contribute to sound propagation in Swedish waters and how this influences the noise level from a pile strike as a function of distance at four study areas along the Swedish coast. Additionally, the study contains a thorough technical description of pile driving activities, basic underwater acoustics and noise effects on marine animals. These effects (injury and behavioral, e.g., flight, but not subtle effects) are demonstrated on representative species such as the harbour porpoise (Phocoena phocoena), Atlantic cod (Gadus morhua), Atlantic herring (Clupea harengus) and on fish larvae and eggs. The study’s authors look atthe original sources of information that other countries base their guidelines and thresholds on, so the recommendations follow scientifically determined levels rather than values that have been rounded off or otherwise altered.The study presents sound levels in three different units, each with different biological relevance to the effects caused by a pile driving activity. None of the sound levels have been frequency weighted for a specific species, as this method is not yet fully established. The first unit used is the sound pressure level SPL(peak), which is the maximum overpressure or underpressure of the noise pulse generated by the pile strike. This unit has a high relevance for behavioural effects. The sound exposure level, SEL, is the calculated energy level over a period of time and expresses the energy of the entire sound pulse. SEL is the unit most related to hearing impairing effects. SEL(ss) is the value for a single strike while SEL(cum) is the cumulative value of a determined number of pulses over a period of time. The review revealed that for Atlantic cod and Atlantic herring there are currently no studies that can be used to determine a species’ specific threshold value for injury, but studies show that loud noise can affect both species negatively. Because of this, the recommended noise levels for injury are based mainly on studies on other species exposed to pile driving noise in laboratory environments, supported by studies conducting large-scale experiments in tanks and oceans. The levels at which fish are at risk of death or sustaining serious injury to internal organs is SPL 207 dB re 1 μPa, SEL(ss) 174 dB re 1 μPa2s and SEL(cum) 204 dB re 1 μPa2s. Note that for injury in fish, the cumulative sound exposure level has higher relevance than the single-strike level as the cited studies found injuries after a certain time period of exposure. The thresholds for fish larvae and eggs are based on the fact that no negative effects were observed at exposures of up to SPL(peak) 217 dB re 1 μPa, SEL(ss) 187 dB re 1 μPa2s and SEL(cum) 207 dB re 1 μPa2s. However, there are relatively few studies on early life stages of fish. There are more species-specific studies on harbour porpoises regarding noise than there are for Atlantic cod and Atlantic herring. Nonetheless, only a few can be used to determine thresholds that will lead to injury or negative behavioural effects. The levels at which there is a risk of a temporary impact on hearing, i.e. temporary threshold shift (TTS), for the harbour porpoises is SPL(peak) 194 dB re 1 μPa, SEL(ss) 164 dB re 1 μPa2s and SEL(cum) 175 dB re 1 μPa2s. When it comes to TTS, the cumulative sound exposure level, SEL(cum), is of primary importance. However, this unit is dependent on a specific time and number of pulses. For permanent threshold shift (PTS), the level is set to SPL(peak) 200 dB re 1 μPa, SEL(ss) 179 dB re 1 μPa2s and SEL(cum) 190 dB re 1 μPa2s. The recommended level should be revised as new relevant studies are conducted.
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2.
  • Andersson, Mathias H., et al. (författare)
  • Underlag för reglering av undervattensljud vid pålning
  • 2016
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • Vid byggnation av broar, havsbaserad vindkraft och andra havsbaserade eller strandnära konstruktioner används det oftast någon form av pålningsteknik för att få ner konstruktionen i botten. Detta innebär att ett fundament, balk eller spont hamras eller vibreras ner i botten, vilket kan generera mycket höga ljudnivåer som sprids ut i vattnet och ner i botten. Ljudnivåerna är så höga att marina organismer kan störas, skadas eller till och med dödas. Idag saknar Sverige fastställda ljudnivåer för när undervattensbuller blir så högt att de kan skada djur i havet. Det saknas därför också vedertagna begränsningsvärden som anger vilka nivåer av undervattensbuller som kan tillåtas för bullrande aktiviteter utan att riskera allvarliga miljöeffekter. Flera länder i Europa har någon form av gränsvärden för när bullernivån under vattnet kan ge upphov till allvarlig miljöpåverkan liksom standarder för hur undervattensbuller skall mätas och rapporteras. Syftet med denna studie var att ta fram ett vetenskapligt underlag rörande ljudet från pålning i havet och dess påverkan på det marina livet. Slutmålet var att utifrån den vetenskapliga information som finns idag ge förslag på ljudnivåer för skador och negativ påverkan som sedan kan användas för att ta fram begränsningsvärden för reglering av undervattensbuller anpassade för svenska vatten och arter. Studien ger ett antal exempel på vilka faktorer som påverkar ljudutbredningen i svenska vatten och hur detta påverkar ett pålningsslags ljudnivå som funktion av avstånd i fyra typområden kring den svenska kusten. Vidare presenteras ingående både tekniska beskrivningar av pålningsaktiviteter, undervattensakustik samt påverkan på marina djur. Denna påverkan (skada och flyktbeteende men ej subtila effekter) demonstreras med hjälp av ett antal typarter som tandvalen tumlare (Phocoena phocoena) och fiskarterna torsk (Gadus morhua) och sill (Clupea clupea) samt fiskägg och fisklarver. I denna studie har författarna gått tillbaka till de originalkällor av information som andra länders gränsvärden grundas på, så att rekommendationerna bygger på vetenskapliga nivåer och inte värden som har avrundats eller på annat sätt ändrats.Studien presenterar ljudnivåer i tre olika enheter då dessa har olika biologisk relevans för påverkan från en pålningsaktivitet. Inga av dessa värden har frekvensviktats för att anpassas för en specifik art då denna metod ännu inte är helt vedertagen. Den första enheten är ljudtrycksnivå SPL(topp), d.v.s. det maximala över- eller undertryck som den av pålningsslaget genererade ljudpulsen har. Denna enhet har hög relevans för beteendepåverkan. För ljudexponeringsnivå SEL, beräknas ljudnivån över en viss tid och tar då med energin i hela ljudpulsen. SEL är den enhet som visats vara bäst relaterad till hörselskador. SEL(enkel) är värdet för en enkel puls och för det kumulativa SEL(kum) har antalet pulser under en viss tid summerats.Litteraturstudien på torsk och sill visar att det i dagsläget inte finns några studier som kan användas för att fastställa en artspecifik ljudnivå för skada men litteraturen visar tydligt på att höga bullernivåer kan påverka torsk och sill negativt. Istället baseras de föreslagna nivåerna i huvudsak på studier på andra arter som har exponerats för pålningsljud i laboratoriemiljö med stöd av studier från mer storskaliga experiment i tankar och hav. De nivåer då fisk riskerar att dödas eller få allvarliga skador på inre organ är 207 dB re 1 μPa SPL(topp), 174 dB re 1 μPa2s SEL(enkel) och 204 dB re 1 μPa2s SEL(kum). Notera att för skada på fisk har det kumulativa värdet högre relevans än enkelvärdet för SEL eftersom studier visar att skador uppkommer efter en viss tids exponering. Nivåerna för påverkan på fiskägg och larver grundas i att inga negativa effekter har observerats vid exponering för ljudtryck från pålning upp till 217 dB re 1 μPa SPL(topp), 187 dB re 1 μPa2s SEL(enkel) och 207 dB re 1 μPa2s SEL(kum). Det finns emellertid mycket få studier relaterat till pålningsljud för dessa livsstadier. För tumlare finns det fler artspecifika studier gjorda relaterat till buller än för torsk och sill. Det är dock endast ett fåtal som kan användas för att bestämma ljudnivåer som leder till skada eller negativ beteendepåverkan. De ljudnivåer som riskerar ge tillfällig hörselnedsättning (TTS) hos tumlare är 194 dB re 1 μPa SPL(topp), 164 dB re 1 μPa2s SEL(enkel) och 175 dB re 1 μPa2s SEL(kum). Det är framförallt den kumulativa ljudexponeringsnivån SEL(kum) som har stor betydelse för just TTS, dock hänger detta värde ihop med en specifik tid och antalet pulser vilket kan vara svårt att uppskatta i förväg. Vidare avseende permanent hörselskada (PTS) är ljudnivån 200 dB re 1 μPa SPL(topp), 179 dB re 1 μPa2s SEL(enkel) och 190 dB re 1 μPa2s SEL(kum). Föreslagna nivåer bör uppdateras när nya relevanta forskningsstudier tillkommer.
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4.
  • Adman, Per, et al. (författare)
  • 171 forskare: ”Vi vuxna bör också klimatprotestera”
  • 2019
  • Ingår i: Dagens nyheter (DN debatt). - Stockholm. - 1101-2447.
  • Tidskriftsartikel (populärvet., debatt m.m.)abstract
    • DN DEBATT 26/9. Vuxna bör följa uppmaningen från ungdomarna i Fridays for future-rörelsen och protestera eftersom det politiska ledarskapet är otillräckligt. Omfattande och långvariga påtryckningar från hela samhället behövs för att få de politiskt ansvariga att utöva det ledarskap som klimatkrisen kräver, skriver 171 forskare i samhällsvetenskap och humaniora.
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5.
  • Alm Fjellborg, Andreas, 1982- (författare)
  • Housing tenure and residential mobility in Stockholm 1990-2014
  • 2018
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • In this thesis the links between housing tenure, income and selective, segregation generating, residential mobility are explored. The development of these links is analysed against the background of housing regime changes in Stockholm between 1990 and 2014. Housing policy changes in Sweden, and Stockholm, promote ownership through, for instance, housing tenure conversions and the tax-system. What this development means for residential mobility trends and may mean for ethnic and economic segregation is explored in three articles. Paper 1 contrasts two time periods and provides an analysis of residential mobility and economic sorting. It is shown that the socioeconomic composition of movers is relatively stable over time while the increasingly owner dominated housing market in Stockholm contributes to stronger socio-spatial residential patterns through the strengthened economic sorting of movers across the whole income scale. Paper 2 has a focus on ethnic and socioeconomic differences in out-mobility from poor neighbourhoods. The findings indicate that foreign background residents are dependent upon housing wealth and income to be able to leave poor neighbourhoods when they move, while the Swedish background group has a variety of resources at their disposal when they move. Paper 3 analyses how housing tenure affects moving, and movers' destinations, in neighbourhoods with high concentrations of non-western foreign-born residents in Stockholm. By comparing two cohorts (1993-2000 and 2001-2008) it is analysed how this relationship develops over time. Housing tenure and income do not seem to be pivotal for who moves, but increasingly important for where movers end up. Results display ethnic differences and how the changing housing market in Stockholm reproduces ethnic segregation. Two main conclusions from the thesis are that (i) the changing housing regime in Stockholm produces stronger economic sorting of movers – this has been affected by the geographically, socioeconomically and ethnically uneven gains from the housing market transformations experienced over the last three decades. (ii) The residential mobility patterns and the economic stratification of residential mobility opportunities that the reconfiguration of Stockholm’s housing market gives rise to increases the economic, political and social marginalization of neighbourhoods characterized by low income levels and high shares of foreign-born residents. Combating ethnic segregation is today even more closely related to the socioeconomic differences between the foreign-born and native-born parts of the population.
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6.
  • Andersson, Henrik, 1968-, et al. (författare)
  • Simulation in Virtual World to Promote Communication
  • 2018
  • Ingår i: Pre-hospital care- Education and training of ambulance professionals. - Noordwijkerhout, The Netherlands.
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • Introduction Communication between ambulance professionals and patients is essential for understanding the patient's lifeworld (Wireklint Sundström & Dahlberg 2010). Simultaneously, communication is challenging to teach and learn within the framework of specific courses. However, simulation in virtual worlds can support the development of new skills such as communication (Combs, Sokolowski & Banks 2016). AimThe aim of this work was to design a simulation-based platform for communication training among ambulance nurse students (ANS). MethodsA qualitative action research approach was used (Coghlan & Casey 2001). Second Life® (SL) was selected since it was an existing virtual world. SL is a web-based flexible three-dimensional platform that allows customization. Interaction and communication with other virtual people can be done through avatars in real time (Hodge, Collins & Giordano 2011). Three ANS and five teachers participated, none of the participants had prior experience of SL. Observations and interviews were used as data and analysed using thematic analysis. Results The participants’ experiences generated three themes: Understanding the virtual worldIt was easy to interact and communicate with other virtual people. However, it took time to feel comfortable to navigate in SL. Technological challengesOne challenge was related to audio-visual problems e.g. not compatible headset, interfering echoes and that the image was distorted at times, which made it difficult to act and move the avatar. Another challenge was associated with the 3D modelling e.g. the capability to use of coordinates, positioning, object dimensioning and the fact that accidental deletions could not be restored. A third challenges that influenced the communication was the difficulty of visualizing clinically relevant care measures such as diagnostic examinations or drug treatment. Finally, there was a challenge to customize the avatars to look like ambulance professionals or a severely ill patient. Learning through avatars Learning through avatars requires that the participants take responsibility for delivering a convincing performance.  Immersion was limited since actions do not take place from a first-person viewpoint. There is a need that the scenario is based on realistic conditions e.g. interiors, equipment, clothing, avatar appearance and behaviour. Conclusion The present system is not suitable for training of medical assessment. Teachers who are considering using virtual worlds in the training for future ambulance professionals should note that an appropriate design is crucial for how the simulation is experienced.  
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7.
  • Andersson, Jan, et al. (författare)
  • Fisk- och skaldjursbestånd i hav och sötvatten 2015 : Resursöversikt
  • 2015
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • I rapporten kan du ta del av bedömningen som görs av situationen för bestånd som regleras inom ramen för EU:s gemensamma fiskeripolitik (GFP). Bedömningarna baseras på det forskningssamarbete och den rådgivning som sker inom det Internationella Havsforskningsrådet (ICES).De bestånd som förvaltas nationellt baseras på de biologiska underlagen och rådgivningen i huvudsak på den forskning och övervakning samt analys som bedrivs av Institutionen för akvatiska resurser (SLU Aqua) vid Sveriges lantbruksuniversitet (SLU) samt yrkesfiskets rapportering.Rapporten omfattar 40 fiskarter uppdelade i olika bestånd, samt sex skal-och blötdjursarter.Nytt för årets upplaga är en beskrivning av hur de provfisken som ligger till grund för analys och rådgivning utförs.Översikten är utarbetad av Sveriges lantbruksuniversitet (SLU), Institutionen för akvatiska resurser (SLU Aqua), på uppdrag av Havs- och vattenmyndigheten.
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8.
  • Hibar, Derrek P., et al. (författare)
  • Novel genetic loci associated with hippocampal volume
  • 2017
  • Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 8
  • Tidskriftsartikel (refereegranskat)abstract
    • The hippocampal formation is a brain structure integrally involved in episodic memory, spatial navigation, cognition and stress responsiveness. Structural abnormalities in hippocampal volume and shape are found in several common neuropsychiatric disorders. To identify the genetic underpinnings of hippocampal structure here we perform a genome-wide association study (GWAS) of 33,536 individuals and discover six independent loci significantly associated with hippocampal volume, four of them novel. Of the novel loci, three lie within genes (ASTN2, DPP4 and MAST4) and one is found 200 kb upstream of SHH. A hippocampal subfield analysis shows that a locus within the MSRB3 gene shows evidence of a localized effect along the dentate gyrus, subiculum, CA1 and fissure. Further, we show that genetic variants associated with decreased hippocampal volume are also associated with increased risk for Alzheimer's disease (r(g) = -0.155). Our findings suggest novel biological pathways through which human genetic variation influences hippocampal volume and risk for neuropsychiatric illness.
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10.
  • Rhedin, S. A., et al. (författare)
  • Protocol Introducing a New Algorithm for Classification of Etiology in Studies on Pediatric Pneumonia: Protocol for the Trial of Respiratory Infections in Children for Enhanced Diagnostics Study
  • 2019
  • Ingår i: Journal of Medical Internet Research. - : JMIR Publications Inc.. - 1438-8871. ; 21:4
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: There is a need to better distinguish viral infections from antibiotic-requiring bacterial infections in children presenting with clinical community-acquired pneumonia (CAP) to assist health care workers in decision making and to improve the rational use of antibiotics. Objective: The overall aim of the Trial of Respiratory infections in children for ENhanced Diagnostics (TREND) study is to improve the differential diagnosis of bacterial and viral etiologies in children aged below 5 years with clinical CAP, by evaluating myxovirus resistance protein A (MxA) as a biomarker for viral CAP and by evaluating an existing (multianalyte point-of-care antigen detection test system [mariPOC respi] ArcDia International Oy Ltd.) and a potential future point-of-care test for respiratory pathogens. Methods: Children aged 1 to 59 months with clinical CAP as well as healthy, hospital-based, asymptomatic controls will be included at a pediatric emergency hospital in Stockholm, Sweden. Blood (analyzed for MxA and C-reactive protein) and nasopharyngeal samples (analyzed with real-time polymerase chain reaction as the gold standard and antigen-based mariPOC respi test as well as saved for future analyses of a novel recombinase polymerase amplification-based point-of-care test for respiratory pathogens) will be collected. A newly developed algorithm for the classification of CAP etiology will be used as the reference standard. Results: A pilot study was performed from June to August 2017. The enrollment of study subjects started in November 2017. Results are expected by the end of 2019.Conclusions: The findings from the TREND study can be an important step to improve the management of children with clinical. © 2019 Journal of Medical Internet Research. All rights reserved.
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11.
  • Ryve, Andreas, et al. (författare)
  • Kartläggning av forskning om formativ bedömning, klassrumsundervisning och läromedel i matematik : Delrapport från skolforsk-projektet
  • 2015
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • The current project focuses on mathematics education, and is partitioned into three subprojects mapping research on formative assessment, classroom teaching, and curriculum programs in mathematics. The rationale for focusing on these three areas is that they are all highly relevant for understanding and improving Swedish mathematics education and students’ knowing of mathematics. Therefore, the aim of the project is to map research on formative assessment, classroom teaching, and curriculum programs in mathematics education.The methodology of the literature review has been inspired by Gough, Oliver, and Thomas (2013), and we have focused on the mapping on journal articles published on Web of Science (WoS).The results from the sample of articles on formative assessment show that strategies of formative assessment in mathematics are positively correlated to students’ performance in mathematics with medium and large effect sizes. However, based on the current mapping it is difficult to specify aspects of how the formative strategies are to be implemented in order to promote students’ knowing of mathematics.Despite the change in perspective of what constitutes knowledge in mathematics to also include reasoning, problem-solving and communication, the map shows that research is mainly focused on examining teaching methods and their effects on students’ skills in mathematics. A closer examination of the studies that do focus on teaching for supporting students in developing competencies like reasoning and problem-solving shows that connections between and comparison of students’ solutions, as well as teachers’ ways of asking questions to support students in explaining their solutions clearly and in detail, are important for students’ learning of these competencies.A central finding stemming from this review of curriculum programs is the complexity involved in how the programs can support teachers in establishing classroom practices. Curriculum resources and teacher resources, as well as other influencing factors, impact the quality of instruction, and studies have begun to point out how curriculum resources and teacher resources uniquely and jointly impact classroom practices. Multiple research articles have expressed the need for teacher support in implementing curriculum programs, by means of professional development, teacher education and support provided by the curriculum programs themselves. Interesting in this regard is the state of the research field concerning the design of educative curriculum programs, and how teachers make use of such support. Studies have proposed design approaches, regarding both the actual development of educative curriculum programs as well as how to use them in teacher education to support prospective teachers’ development of knowledge. Further, although research has revealed that it is important to prepare for teaching in certain ways, we found very little research that explicitly analyzed how teachers actually prepare for teaching a mathematics lesson.Limitations of the project include: (1) the lack of searching in potentially relevant databases, (2) the fact that a relatively small proportion of articles found in the search have been coded, (3) that we have not engaged in deep considerations as to whether and in what ways results from international research are relevant in the Swedish context, and (4) that we therefore have not been able to synthesize the results of the study. In relation to the Swedish context (Hemmi & Ryve, 2014; Boesen et al., 2014), international research (Hattie, 2009; Smith & Stein, 2011), and the current project’s findings, we recommend that Skolforskningsinstitutet focus on two aspects of great importance for developing students’ knowing of mathematics. First, Skolforskningsinstitutet should synthesize research that supports actors, such as teachers and principals, in acting within school practices. In the case of teachers, support is needed to engage them in actively anticipating students’ thinking, using curriculum programs effectively, introducing mathematical content, acting in group work, formatively assessing students’ learning, and orchestrating whole-class mathematical discussions. Secondly, actors within school practices need support not only in initiating and implementing developments but also in institutionalizing such developments. Skolforskningsinstitutet should specify the kind of support needed in order to ensure that material, routines, competences, and organizations become integral and permanent features of Swedish school practice. 
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12.
  • Satizabal, Claudia L., et al. (författare)
  • Genetic architecture of subcortical brain structures in 38,851 individuals
  • 2019
  • Ingår i: Nature Genetics. - : Nature Publishing Group. - 1061-4036 .- 1546-1718. ; 51:11, s. 1624-
  • Tidskriftsartikel (refereegranskat)abstract
    • Subcortical brain structures are integral to motion, consciousness, emotions and learning. We identified common genetic variation related to the volumes of the nucleus accumbens, amygdala, brainstem, caudate nucleus, globus pallidus, putamen and thalamus, using genome-wide association analyses in almost 40,000 individuals from CHARGE, ENIGMA and UK Biobank. We show that variability in subcortical volumes is heritable, and identify 48 significantly associated loci (40 novel at the time of analysis). Annotation of these loci by utilizing gene expression, methylation and neuropathological data identified 199 genes putatively implicated in neurodevelopment, synaptic signaling, axonal transport, apoptosis, inflammation/infection and susceptibility to neurological disorders. This set of genes is significantly enriched for Drosophila orthologs associated with neurodevelopmental phenotypes, suggesting evolutionarily conserved mechanisms. Our findings uncover novel biology and potential drug targets underlying brain development and disease.
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13.
  • Aggestam, Emil, 1992, et al. (författare)
  • Multi-objective design optimisation of transition zones between different railway track forms
  • 2018
  • Ingår i: Proceedings of the 11th International Conference on Contact Mechanics and Wear of Rail/wheel Systems, CM 2018. - : TU Delft. - 2590-0609. - 9789461869630 ; , s. 1-6
  • Konferensbidrag (refereegranskat)abstract
    • The vertical dynamic interaction between vehicle and railway track is simulated in the time domain using an extended state space vector approach. The track model includes a transition zone between slab track on a bridge and ballasted track on an embankment. By considering a multi-objective optimisation problem, solved using a genetic algorithm, selected vehicle and track responses are simultaneously minimised by optimising the distributions of rail pad stiffness and sleeper spacing in the transition zone. It is shown that the magnitudes of the maximum dynamic loads in the optimised transition zone can be reduced to be similar as the magnitudes far away from the transition zone.
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14.
  • Ahlberg, Erik, et al. (författare)
  • "Vi klimatforskare stödjer Greta och skolungdomarna"
  • 2019
  • Ingår i: Dagens nyheter (DN debatt). - 1101-2447.
  • Tidskriftsartikel (populärvet., debatt m.m.)abstract
    • DN DEBATT 15/3. Sedan industrialiseringens början har vi använt omkring fyra femtedelar av den mängd fossilt kol som får förbrännas för att vi ska klara Parisavtalet. Vi har bara en femtedel kvar och det är bråttom att kraftigt reducera utsläppen. Det har Greta Thunberg och de strejkande ungdomarna förstått. Därför stödjer vi deras krav, skriver 270 klimatforskare.
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15.
  • Akbari, Saaed, et al. (författare)
  • Effect of PCB cracks on thermal cycling reliability of passive microelectronic components with single-grained solder joints
  • 2019
  • Ingår i: Microelectronics and reliability. - : Elsevier BV. - 0026-2714 .- 1872-941X. ; 93, s. 61-71
  • 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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16.
  • Andell, Pontus, et al. (författare)
  • Epidemiology of valvular heart disease in a Swedish nationwide hospital-based register study
  • 2017
  • Ingår i: Heart. - : BMJ. - 1355-6037 .- 1468-201X. ; 103:21, s. 1696-1703
  • Tidskriftsartikel (refereegranskat)abstract
    • Objective: Transitions in the spectrum of valvular heart diseases (VHDs) in developed countries over the 20th century have been reported from clinical case series, but large, contemporary population-based studies are lacking.Methods: We used nationwide registers to identify all patients with a first diagnosis of VHD at Swedish hospitals between 2003 and 2010. Age-stratified and sex-stratified incidence of each VHD and adjusted comorbidity profiles were assessed.Results: In the Swedish population (n=10 164 211), the incidence of VHD was 63.9 per 100 000 person-years, with aortic stenosis (AS; 47.2%), mitral regurgitation (MR; 24.2%) and aortic regurgitation (AR; 18.0%) contributing most of the VHD diagnoses. The majority of VHDs were diagnosed in the elderly (68.9% in subjects aged ≥65 years), but pulmonary valve disease incidence peaked in newborns. Incidences of AR, AS and MR were higher in men who were also more frequently diagnosed at an earlier age. Mitral stenosis (MS) incidence was higher in women. Rheumatic fever was rare. Half of AS cases had concomitant atherosclerotic vascular disease (48.4%), whereas concomitant heart failure and atrial fibrillation were common in mitral valve disease and tricuspid regurgitation. Other common comorbidities were thoracic aortic aneurysms in AR (10.3%), autoimmune disorders in MS (24.5%) and abdominal hernias or prolapse in MR (10.7%) and TR (10.3%).Conclusions: Clinically diagnosed VHD was primarily a disease of the elderly. Rheumatic fever was rare in Sweden, but specific VHDs showed a range of different comorbidity profiles . Pronounced sex-specific patterns were observed for AR and MS, for which the mechanisms remain incompletely understood.
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17.
  • Andersson, Andreas, 1980-, et al. (författare)
  • A soil-steel bridge under high-speed railways
  • 2017
  • Ingår i: Archives of Institute of Civil Engineering. - Poznan. ; , s. 45-52
  • Konferensbidrag (refereegranskat)abstract
    • This paper presents some recent research on railway bridge dynamics with application to buried flexible structures. Based on a combination of simulations and full-scale testing, current research indicates that a rather comprehensive numerical model is required to accurately describe the response from passing trains.
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18.
  • Andersson, Andreas, 1981- (författare)
  • Air-sea exchange of O2 and CO2 : Processes controlling the transfer efficiency
  • 2017
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • World oceans cover more than 70% of the earth surface and constitutes a major sink of atmospheric CO2. Two of the most important gases in the marine carbon cycling are O2 and CO2 and hence accurate descriptions of the air-sea gas exchange of these gases are crucial. Still there is a lack of knowledge of the relative importance of processes controlling the efficiency of the air-sea gas transfer. This is especially true for Arctic and high latitude seas were studies on air-sea gas exchange are few. By studying processes causing water-side turbulence, using gases of different solubility and various measurement techniques, more knowledge on the governing processes can be obtained.Here we present the very first air-sea fluxes of O2 using atmospheric eddy covariance measurements and investigate the dependence between the gas transfer velocity of O2 and turbulence generated by the mean wind. The instrument was found to suffer from the limited precision and time response, causing significant corrections on the O2 flux. After correcting for this, the O2 fluxes displays an anti-correlation with the air-sea fluxes of CO2 in agreement with the measured air-sea gradient of O2. The transfer velocities for O2 indicates a stronger wind dependence than other commonly used parameterizations of the transfer velocity for CO2 and O2, this especially for wind speeds > 5 m s-1 where the typical onset of wave breaking occur.During two winter months eddy covariance measurements were taken over a high Arctic fjord. The data revealed a significant enhancement of the gas transfer velocity for CO2 from water-side convection, generated by cooling of surface waters. The dependence between water-side convection and gas transfer velocity were found for winds as high as 9 m s-1, but were strongest for wind speeds< 7  m s-1.  The data also showed on enhanced air-sea gas transfer of CO2 when conditions were unstable very close to neutral. This enhanced transfer were associated to increased contribution to the CO2 flux from downdraft of air with higher concentrations of CO2.  The combined effect of water-side convection and turbulence generated by wind results in a very effective transfer, thus the air-sea gas exchange at these latitudes may be significantly underestimated.
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19.
  • Andersson, Andreas, et al. (författare)
  • Air-sea gas transfer in high Arctic fjords
  • 2017
  • Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 44:5, s. 2519-2526
  • Tidskriftsartikel (refereegranskat)abstract
    • In Arctic fjords and high-latitude seas, strong surface cooling dominates during a large part of the year, generating water-side convection (w*w) and enhanced turbulence in the water. These regions are key areas for the global carbon cycle; thus, a correct description of their air-sea gas exchange is crucial. CO2-data were measured via the eddy covariance technique in marine Arctic conditions and reveal that water-side convection has a major impact on the gas transfer velocity. This is observed even at wind speeds as high as 9 m s-1, where convective motions are generally thought to be suppressed by wind-driven turbulence. The enhanced air-sea transfer of CO2 caused by water-side convection nearly doubled the CO2uptake, after scaled to open sea conditions the contribution from  to the CO2 flux remained as high as 34%; this phenomenon is expected to be highly important for the total carbon uptake in marine Arctic areas.
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20.
  • Andersson, Andreas, 1980-, et al. (författare)
  • Bärförmåga hos inklädnadssystem vid stötbelastning från fallande bergblock
  • 2015
  • Ingår i: Bergmekanikdag 2015. - Stockholm : Stiftelsen Bergteknisk forskning.
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • Inner lining system in tunnels is a method to prevent water ingress and forming of ice in the traffic area. A solution that is common in Norway is based on stretching a sealing membrane between rock anchorages that forms a gap to the primary rock strengthening. The membrane is in turn protected by a layer of shotcrete towards the traffic area. The rock strengthening is designed to resist all loads from the rock mass independent of the inner lining system. A problem is however how to perform inspections and conditional assessment of the rock strengthening, since the gap is usually small. Other topics are what loads the inner lining system should be designed for. In TRVK Tunnel 11, the load of a local falling rock of 600 kg is stipulated, assuming to act on a surface of 0.2×0.2 m. Furthermore, the inner lining system should be designed to resist what is connoted as an extreme rock load of 6 metric ton, acting on a 1×1 m area, even when a primary rock strengthening is present. Similar inner lining systems have been used in e.g. Norra länken, parts of Citybanan in Stockholm and is planned to be used for the Stockholm Bypass project.In the present paper, results from a recent research project are presented, aiming at investigating the structural manner of action of the aforementioned inner lining system. A series of concrete slabs have been tested, both until static failure and with a 600 kg drop weight from different heights. All tested slabs resulted in flexural failure and showed a significant ductility. For several of the slabs tested for impact loading, significant spalling from the soffit was obtained, at the most corresponding to a mass of 16 kg. Three of the slabs tested for impact load were manufactured with an outer layer of steel fibre reinforced shotcrete. None of these slabs showed any significant spalling, despite a free fall height up to 2 m.Several FE-analyses have also been performed, accounting for the nonlinear material properties of concrete. The results showed good agreement with the conducted experiments, both regarding static loading, cracking and impact load. A similar analysis was also done for the whole inner lining system. The results showed a larger load capacity compared to the experiments, but still with a rather localised failure.
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21.
  • Andersson, Andreas, 1980- (författare)
  • Dynamic analysis of simply supported slab bridges
  • 2019
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • This report present results from simulations of simply supported concrete slab bridges for railway traffic. The geometry follows the Swedish standard deck models according to design drawing B2447-2 and B2447-8, with span lengths ranging from 2-8 m. For each bridge four different configurations are studied; straight or skewed bridge deck and short or long edge beams. In addition, a case of higher mass due to increased ballast depth is studied. In total 78 different bridge configurations are included.According to the numerical models the first natural frequency range from about 15-80 Hz depending on span length and configuration. In all simulations the first three modes of vibration are included. The limit criteria is a peak deck acceleration of 3.5 m/s2 when loaded by the HSLM-A train model. Including a speed safety factor 1.2 according to EN 1991-2 results in an allowable speed that range from 175-350 km/h depending on the bridge configuration. The allowable speed is somewhat higher for the skewed bridges compared to straight bridges. Increased mass results in lower acceleration but also lower resonance speed. An increase in ballast depth from 0.6 to 1.2 m generally results in lower allowable speed, except for the shortestbridges in the study.It should be noted that the above conclusions are based only on simulations. Before upgrading these bridges to speeds higher than 200 km/h experimental validation is recommended. On the other hand, most existing real trains are likely to result insignificantly lower dynamic response compared to the HSLM-A trains.
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22.
  • Andersson, Andreas, 1980-, et al. (författare)
  • Dynamics of railway bridges, analysis and verification by field tests
  • 2015
  • Ingår i: EVACES'15, 6th International Conference On Experimental Vibration Analysis For Civil Engineering Structures. - : EDP Sciences.
  • Konferensbidrag (refereegranskat)abstract
    • The following paper discusses different aspects of railway bridge dynamics, comprising analysis, modelling procedures and experimental testing. The importance of realistic models is discussed, especially regarding boundary conditions, load distribution and soil-structure interaction. Two theoretical case studies are presented, involving both deterministic and probabilistic assessment of a large number of railway bridges using simplified and computationally efficient models. A total of four experimental case studies are also introduced, illustrating different aspects and phenomena in bridge dynamics. The excitation consists of both ambient vibrations, train induced vibrations, free vibrations after train passages and controlled forced excitation.
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23.
  • Andersson, Andreas, 1980-, et al. (författare)
  • Dynamisk kontroll av järnvägsbroar, inverkan av 3D-effekter
  • 2016
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • I föreliggande rapport redovisas dynamiska analyser av järnvägsbroar för höghastighetståg. En jämförelse i dynamisk respons mellan 2D- och 3D-modeller har utförts för ett mindre urval av plattbroar, balkbroar och lådbroar. Varje tvärsnitt har först optimerats att precis klara de dynamiska kraven avseende 2D-dynamik, utan beaktande av den statiska dimensioneringen. I många fall skulle tvärsnitten troligen behöva ökas för att klara den statiska bärförmågan.Plattbroar med spännvidder från 10 – 25 m och 1 – 4 fack har analyserats. I flertalet fall, främst vid kortare spännvidder, är egenfrekvensen för böjning lägre i 3D-modellen jämfört med 2D-modellen. Detta beror på mindre medverkande tvärsnitt i böjning i 3D (shear-lag). Detta resulterar i en lägre resonanshastighet och därmed ofta en större dynamisk respons för samma hastighetsintervall. I övrigt överensstämmer det dynamiska verkningssättet väl mellan 2D och 3D. Inverkan av vridning synes inte vara styrande för de studerade fallen.På motsvarande sätt har balkbroar med spännvidder från 20 – 40 m och 1 – 4 fack analyserats. På samma sätt som för plattbroar ger balkbroar lägre böjfrekvens i 3D jämfört med 2D. För dubbelspårsbroar är skillnaden i respons mellan 2D och 3D liknande som för plattbroar. För enkelspåriga balkbroar visar 3D-modellen i några fall en avsevärt lägre respons utan utpräglade resonanstoppar inom samma hastighets­intervall som 2D-modellen. Orsaken tros vara en kombination av upplagens excentricitet och brons massa, vilket vid vertikal böjning bidrar till en horisontell masströghet. Detta visas i de flesta fall kunna beskrivas med en modifierad 2D-modell.Lådbroar med spännvidd 40 – 70 m i 1 – 3 fack har analyserats. P.g.a. hög vridstyvhet är egenfrekvensen för vridning mycket högre än första böjmoden och p.g.a. mindre shear-lag är egenfrekvensen för böjning likvärdig i 2D och 3D. Detta ger små skillnader i dynamisk respons mellan 2D och 3D-modellerna.I de fall dynamiska kontroller utförs med förenklade metoder enligt (Svedholm & Andersson, 2016) föreslås att följande beaktas:Första böjfrekvensen n0 bör beakta inverkan av shear-lag och upplagens excentricitet baserat på en 3D-modell, vilket används som indata i design­diagrammen.Då första vridmoden nT < 1.2n0 bör en fullständig dynamisk kontroll utföras i 3D.I de fall en 3D-modell visar flera närliggande egenmoder för böjning med samma form bör en fullständig dynamisk kontroll utföras i 3D.
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24.
  • Andersson, Andreas, 1988 (författare)
  • Electric machine control for energy efficient electric drive systems
  • 2015
  • Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Pure electric vehicles and hybrid electric vehicles are of increasing interest in the automotive industry, much due to challenges such as emission level legislations and the environmental impact of the transportation sector. When continuously striving for better performing and more energy efficient electric powertrains, with high drivability and redundancy, there is an ever increasing need for further research and development in the areas of controls, design and system level optimization.Over the past decade, noise and vibrations from electric drives has increasingly become an area of attention for both academia and industry. The absence of the broad band noise from the internal combustion engine brings new noise, vibration and harshness (NVH) challenges for electric propulsion applications. Magnetic noise from electrical machines is of particular interest in automotive applications. It is not only related to the physical design and mounting of the electrical machine but also to the choice of control approach and voltage modulation strategy.This thesis is focused on energy efficiency enhancements in the electric drive system, primarily on the control of the three phase inverter. In addition to the energy efficiencyperspective, also the appearance of electromagnetic forces and NVH-perspectives are considered. Alternative modulation techniques are investigated, where the so called discontinuous pulse width modulation is is proven to decrease the inverter losses, substantially.The appearance of electromagnetic forces is investigated extensively, with focus on radial forces acting as attractive or repulsive forces between the rotor and the stator. Its influence on stator deformations, and consequently noise and vibrations, is investigated where also influence of machine design, modulation techniques and perceived annoyance of the radiated sound are included.The scientific contribution can be summarized with two parts. Firstly, the interdisciplinary research where energy efficiency enhancements are coupled to NVHperformance. Secondly, the cause and effect of electromagnetic forces as the link between machine design, controls and NVH-perspectives. It is proven that when using discontinuous PWM(DPWM) instead of synchronous PWM (SPWM), the inverter losses can be decreased with up to -17 percent. While complementing the modulationwith randomization of the switching frequency the increase in perceived annoyance, due to increased radiated noise when using DPWM, is significantly decreased. At rotational speeds above base speed, no difference in perceived annoyance between DPWM and SPWM could statistically be ensured when randomization is used.At a randomization level with a variance of 1000 Hz the noise is comparable with the magnitude of the harmonics themselves, hence further randomization in terms of increased variance is without any gain.
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25.
  • Andersson, Andreas, 1988 (författare)
  • Electric Machine Control for Energy Efficient Electric Drive Systems
  • 2018
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Over the past decade, electric vehicles has increasingly become an area of attention for both academia and industry, much due to challenges such as emissions legislation and the environmental impact of the transportation sector. The absence of the broadband noise from the internal combustion engine brings new acoustic challenges for electric propulsion applications. Magnetic noise from electrical machines is of particular interest in automotive applications. It is not only related to the geometrical design of the machine, but also to the selection of control approach and voltage modulation strategy. This thesis focuses primarily on software-based electric drive system energy efficiency enhancements, supported by extensive experimental testing, incorporating aspects of dynamic performance and acoustic perspectives. The scientific contribution can be summarized in three parts. Firstly, the interdisciplinary research where efficiency enhancements are coupled to acoustic performance. Secondly, the cause and effect of electromagnetic forces as the link between machine design, controls, and perceived acoustic annoyance. Lastly, the findings from the research on optimization-based inverter control and motion sensorless operation. It is proven that alternative modulation techniques can reduce the inverter losses with up to 15 % without degradation of the perceived acoustic annoyance. Moreover, research on finite control set model predictive current control and moving horizon rotor position estimation is presented. It is shown that the proposed solutions are feasible, and that the associated optimization problems at hand can be solved in real-time while exploiting their respective attractive properties. Furthermore, excellent performance is obtained in comparison to state of the art alternatives, at the expense of increased computational complexity.
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26.
  • Andersson, Andreas, et al. (författare)
  • Enhanced Air–Sea Exchange of Heat and Carbon Dioxide Over a High Arctic Fjord During Unstable Very-Close-to-Neutral Conditions
  • 2019
  • Ingår i: Boundary-layer Meteorology. - : Springer Science and Business Media LLC. - 0006-8314 .- 1573-1472. ; 170:3, s. 471-488
  • Tidskriftsartikel (refereegranskat)abstract
    • Eddy-covariance measurements made in the marine atmospheric boundary layer above a high Arctic fjord (Adventfjorden, Svalbard) are analyzed. When conditions are unstable, but close to neutral −0.1 < z/L < 0, where z is the height, and L is the Obukhov length, the exchange coefficient for sensible heat CH is significantly enhanced compared with that expected from classical surface-layer theory. Cospectra of the vertical velocity component (w) and temperature (T) reveal that a high-frequency peak develops at f ≈ 1 Hz for z/L > − 0.15. A quadrant analysis reveals that the contribution from downdrafts to the vertical heat flux increases as conditions become close to neutral. These findings are the signature of the evolving unstable very-close-to-neutral (UVCN) regime previously shown to enhance the magnitude of sensible and latent heat fluxes in the marine surface layer over the Baltic Sea. Our data reveal the significance of the UVCN regime for the vertical flux of the carbon dioxide (CO2) concentration (C). The cospectrum of w and C clearly shows how the high-frequency peak grows in magnitude for z/L > − 0.15, while the high-frequency peak dominates for z/L > − 0.02. As found for the heat flux, the quadrant analysis of the CO2 flux shows a connection between the additional small-scale turbulence and downdrafts from above. In contrast to the vertical fluxes of sensible and latent heat, which are primarily enhanced by the very different properties of the air from aloft (colder and drier) during UVCN conditions, the increase in the air–sea transfer of CO2 is possibly a result of the additional small-scale turbulence causing an increase in the water-side turbulence. The data indicate an increase in the gas-transfer velocity for CO2 for z/L > − 0.15 but with a large scatter. During the nearly 2 months of continuous measurements (March–April 2013), as much as 36% of all data are associated with the stability range −0.15 < z/L < 0, suggesting that the UVCN regime is of significance in the wintertime Arctic for the air–sea transfer of heat and possibly also CO2.
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27.
  • Andersson, Adam, 1979, et al. (författare)
  • Finite element approximation of Lyapunov equations for the computation of quadratic functionals of SPDEs
  • 2019
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • The computation of quadratic functionals of the solution to a linear stochastic partial differential equation with multiplicative noise is considered. An operator valued Lyapunov equation, whose solution admits a deterministic representation of the functional, is used for this purpose and error estimates are shown in suitable operator norms for a fully discrete approximation of this equation. Weak error rates are also derived for a fully discrete approximation of the stochastic partial differential equation, using the results obtained from the approximation of the Lyapunov equation. In the setting of finite element approximations, a computational complexity comparison reveals that approximating the Lyapunov equation allows for cheaper computation of quadratic functionals compared to applying Monte Carlo or covariance-based methods directly to the discretized stochastic partial differential equation. Numerical simulations illustrates the theoretical results.
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28.
  • Andersson, Andreas, 1980-, et al. (författare)
  • Full-Scale Dynamic Testing of a Railway Bridge Using a Hydraulic Exciter
  • 2018
  • Ingår i: EXPERIMENTAL VIBRATION ANALYSIS FOR CIVIL STRUCTURES. - Cham : SPRINGER INTERNATIONAL PUBLISHING AG. - 9783319674438 - 9783319674421 ; , s. 354-363
  • Konferensbidrag (refereegranskat)abstract
    • This paper presents a full-scale dynamic testing on a simply supported railway bridge with integrated end-shields, by using a hydraulic exciter. Experimental frequency response functions are determined based on load controlled frequency sweeps. Apart from accurate estimates of natural frequencies, damping and mode shapes, the experimental testing also gives valuable information about the dynamic characteristics at resonance and amplitude dependent nonlinearities. Numerical models are used to simulate the dynamic response from passing trains which is compared to experimental testing of similar train passages. The results show that the bridge deck is partially constrained due to the interaction between the end-shields and the wing walls with the surrounding soil. Measurements at the supports also show that the flexibility of the foundation needs to be accounted for. An updated numerical model is able to accurately predict the response from passing trains. The response is lower than that predicted from the initial simulations and the bridge will fulfil the design requirements regarding vertical deck acceleration.
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29.
  • Andersson, Andreas, et al. (författare)
  • Influence of Inverter Modulation Strategy on Electric Drive Efficiency and Perceived Sound Quality
  • 2016
  • Ingår i: IEEE Transactions on Transportation Electrification. - : IEEE. - 2332-7782. ; 2:1, s. 24-35
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper presents an evaluation of differentmodulation techniques and different levels of switching frequencyrandomization for a rear axle electrical drive unit used in auto-motive applications. Inverter and machine losses, and perceivedsound quality of high-frequency acoustic noise are investigated byfinite element calculations, experimental testing, and subjectivenoise assessment. Additionally, stator current harmonics, airgapflux density harmonics, and force density harmonics are comparedfor space vector modulation (SVM) and discontinuous pulsewidthmodulation through finite element modeling. The main conclusionis that, primarily in the field weakening region, significant energysavings can be achieved (up to 17% decrease in total inverter losseswith a switching frequency of 10 kHz). This is obtained withoutdeterioration of perceived sound quality by the use of discontinu-ous pulsewidth modulation with switching frequency randomiza-tion. Furthermore, randomization of the switching frequency doesnot improve the perceived sound quality of the acoustic noise whenusing SVM. However, for discontinuous pulsewidth modulation,improvements in perceived sound quality when randomizing theswitching frequency are observed, primarily below base speed.
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30.
  • Andersson, Andreas, 1980-, et al. (författare)
  • Load capacity of inner lining system s due to impact from falling rocks
  • 2015
  • Ingår i: SEE Tunnel. - Dubrovnik.
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • The inner lining concept is a method to prevent water leakage and the risk of icing inside tunnels and is frequently used in countries with cold climate. Blocks of falling ice may result is a severe safety risk in both road and railway tunnels. Although several established inner lining systems exist, finding the optimal solution considering function, maintenance- and investment cost is a challenging task. A new system has recently been used in Sweden and is due to its success planned to be used for the Stockholm Bypass, an 18 km road tunnel project in Stockholm.A set of design criterions has been stipulated for the inner lining system. In this paper, the case of impact loading from falling rocks is studied. The inner lining system is required to withstand the impact of a 600 kg block landing on a square surface of 0.2x0.2 m. The free fall height, i.e. the distance to the rock surface, is typically less than 0.5 m but may span up to 1.5 m in some cases. A too conservative design may result in an unnecessary thick structure and lack of knowledge of the impact phenomena may result in an unsafe design.An extensive experimental program has been performed, consisting of representative parts of the inner lining system. A mass of 600 kg is dropped onto the structure and the results are compared with numerical simulations. The experiments show that the current system is rather ductile but that local concrete fallouts may occur at extreme free fall heights.
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31.
  • Andersson, Andreas, et al. (författare)
  • Modeling and simulations of quantum phase slips in ultrathin superconducting wires
  • 2015
  • Ingår i: Physical Review B. Condensed Matter and Materials Physics. - : American Physical Society. - 1098-0121 .- 1550-235X. ; 91:13
  • Tidskriftsartikel (refereegranskat)abstract
    • We study quantum phase slips (QPS) in ultrathin superconducting wires. Starting from an effective one-dimensional microscopic model, which includes electromagnetic fluctuations, we map the problem to a (1+1)-dimensional gas of interacting instantons. We introduce a method to calculate the tunneling amplitude of quantum phase slips directly from Monte Carlo simulations. This allows us to go beyond the dilute instanton gas approximation and study the problem without any limitations of the density of QPS. We find that the tunneling amplitude shows a characteristic scaling behavior near the superconductor-insulator transition. We also calculate the voltage-charge relation of the insulating state, which is the dual of the Josephson current-phase relation in ordinary superconducting weak links. This evolves from a sinusoidal form in the regime of dilute QPS to more exotic shapes for higher QPS densities, where interactions are important.
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32.
  • Andersson, Anders, et al. (författare)
  • Parameterization procedure of a powertrain model for a driving simulator
  • 2016
  • Ingår i: Advances in Transportation Studies. - : Aracne editrice. - 1824-5463. ; 1, s. 99-112
  • Tidskriftsartikel (refereegranskat)abstract
    • The automotive industry is facing a major challenge to reduce environmental impacts. As a consequence, the increasing diversity of powertrain configurations put a demand on testing and evaluation procedures. One of the key tools for this purpose is simulators. In this paper a powertrain model and a procedure for parameterizing it, using chassis dynamometers and a developed pedal robot are presented. The parameterizing procedure uses the on-board diagnostics of the car and does not require any additional invasive sensors.Thus, the developed powertrain model and parameterization procedure provide a rapid non- invasive way of modelling powertrains of test cars. The parameterizing procedure has been used to model a front wheel drive Golf V with a 1.4L multi-fuel engine and a manual gearbox. The achieved results show a good match between simulation results and test data. The powertrain model has also been tested in real-time in a driving simulator.
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33.
  • Andersson, Anders, et al. (författare)
  • Parameterization Procedure of a Powertrain Model for a Driving Simulator
  • 2015
  • Ingår i: Proceedings  of the 2015 Road Safety &amp; Simulation International Conference.
  • Konferensbidrag (refereegranskat)abstract
    • The automotive industry is facing a major challenge to reduce environmental impacts. As a consequence, the increasing diversity of powertrain configurations put a demand on testing and evaluation procedures. One of the key tools for this purpose is simulations.In this paper a powertrain model and a procedure for parameterizing it, using chassis dynamometers and a developed pedal robot are presented. The parameterizing procedure uses the on-board diagnostics of the car and does not require any additional invasive sensors. Thus, the developed powertrain model and parameterization procedure provide a rapid non-invasive way of modelling powertrains of test cars. The parameterizing procedure has been used to model a front wheel drive Golf V with a 1.4L multi-fuel engine and a manual gearbox. The achieved results show a good match between simulation results and test data. The powertrain model has also been tested in real-time in a driving simulator.
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34.
  • Andersson, Andreas, 1980-, et al. (författare)
  • Passive and Adaptive Damping Systems for Vibration Mitigation and Increased Fatigue Service Life of a Tied Arch Railway Bridge
  • 2015
  • Ingår i: Computer-Aided Civil and Infrastructure Engineering. - : Wiley. - 1093-9687 .- 1467-8667. ; 30:9, s. 748-757
  • Tidskriftsartikel (refereegranskat)abstract
    • n this article, the use of external damping systems for vibration mitigation of railway bridge dynamics is studied. For a presented case study bridge, the performance of different tuned mass damper systems (TMDs) is studied. During train passage, the change in dynamic characteristics of the bridge may produce a significant detune to a passive TMD. Therefore, routines for a variable stiffness TMD using incremental frequency estimates are developed. Based on numerical simulations, the cumulative fatigue damage is calculated for different damper systems. Due to resonant behavior, the results are found to highly depend on the train speed. Based on an assumed probability density function for the train speed, fragility curves are produced to express the probability of fatigue failure as a function of the number of train passages.
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35.
  • Andersson, Andreas, 1980-, et al. (författare)
  • Pilot testing of a hydraulic bridge exciter
  • 2015
  • Ingår i: EVACES'15, 6th International Conference on Experimental Vibration Analysis For Civil Engineering Structures. - Zurich : EDP Sciences. ; , s. 02001-
  • Konferensbidrag (refereegranskat)abstract
    • This paper describes the development of a hydraulic bridge exciter and its first pilot testing on a full scale railway bridge in service. The exciter is based on a hydraulic load cylinder with a capacity of 50 kN and is intended for controlled dynamic loading up to at least 50 Hz. The load is applied from underneath the bridge, enabling testing while the railway line is in service. The system is shown to produce constant load amplitude even at resonance. The exciter is used to experimentally determine frequency response functions at all sensor locations, which serve as valuable input for model updating and verification. An FE-model of the case study bridge has been developed that is in good agreement with the experimental results.
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36.
  • Andersson, Andreas, 1980- (författare)
  • Simplified approach to dynamic analysis of railway bridges for high-speed trains
  • 2018
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • In this report the analysis of 278 existing railway bridges is presented. The aim is to investigate how many of these bridges that potentially can be upgraded to higher speeds, with a target of 250 km/h. Due to the vast amount of bridges and the limited resources, the analyses are performed using simplified 2D models. The analysis is afflicted with several uncertainties, both regarding input parameters as well as model uncertainties. The results should therefore be interpreted carefully and primarily serve as an indicator for which bridges that may or may not meet the requirements. Large uncertainties are especially expected for portal frame bridges due to its inherently large interaction with the surrounding embankment and 3D behaviour.The results from the analysis show that a total of 22 bridges theoretically fail to meet the dynamic requirements. A combination of refined analysis and experimental validation is recommended to better assess the dynamic response for these bridges. Among the most critical cases are several steel-concrete composite bridges, that due to a combination of low mass and low natural frequency may be prone to resonant loading. Retrofitting with external dampers may for some bridges be a viable solution.
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37.
  • Andersson, Andreas, 1980-, et al. (författare)
  • Train-Track-Bridge Interaction for non-ballasted Railway Bridges on High-Speed Lines
  • 2017
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • This report contains a comprehensive parametric study on the coupled dynamic train–track–bridge interaction (TTBI) system for non-ballasted railway bridges. The existing design limits in Eurocode EN 1990 A2 regarding vertical deck acceleration and vertical deck displacement is compared with the wheel–rail forces and car body acceleration from simulations.The simulations are based on a 2D TTBI model with linear Hertzian contact that allows for loss of contact. The model has been verified against both other numerical simulations as well as experiments, all with good agreement. The parametric study consists of a large number of theoretical bridges, all optimized to reach the limit of either vertical deck acceleration or vertical deck displacement. The study comprises both single- and double track bridges.The track irregularities are found to be of paramount importance. Two different levels are therefore studied; “higher track quality” corresponding to a well-maintained track for high-speed railways and “lower track quality” corresponding to the Alert Limit in EN 13848-5. The final conclusions are based on the “lower track quality” in order not to underestimate the risk of running safety and passenger comfort. Simulations with the bridge excluded show that the additional contribution from the bridge is low, especially for the lower track quality.The existing limit for vertical deck acceleration is set to 5 m/s2 in EN 1990 A2 and is based on a very simple assumption of the gravity acceleration reduced by a factor 2. The results in this report show that this likely is a too conservative measure of the running safety. Based on the wheel–rail forces from the simulations, the resulting wheel unloading factor and duration of contact loss does not reach critical values before the deck acceleration is beyond 30 m/s2.In EN 1990 A2, a vertical car body acceleration of 1 m/s2 is stipulated as “very good level of comfort” and is indirectly limited by the vertical deck displacement. Good agreement is generally found in the simulations between deck displacement and expected car body acceleration. In the simulations, the limit for car body acceleration is always exceeded before the running safety is compromised.
  •  
38.
  • Andersson, Andreas, et al. (författare)
  • Train-Track-Bridge Interaction for non-ballasted Railway Bridges on High-Speed Lines
  • 2018
  • Ingår i: Railways 2018.
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • This paper presents the result from a parametric study of the dynamic response of railway bridges during train passage. A 2D coupled train-track-bridge interaction (TTBI) model is used to calculate the response from both the bridge and the vehicle.To assure traffic safety and riding comfort, Eurocode EN 1990/A2 gives a set of design limits for railway bridges on high-speed lines. The vertical bridge deck acceleration and displacement are often of main interest. For bridges with non-ballasted tracks the vertical deck acceleration is limited to 5 m/s2, simply obtained as the gravity divided by a safety factor 2, under the assumption that loss of wheel-rail contact will occur at 1g. The vertical bridge deck displacement is an implicit measure to assure riding comfort, based on a limited set of simulations carried out in the 1980ies and 1990ies.The main aim of this paper is to study the relation between the vertical bridge deck acceleration and the risk of derailment as well as the relation between the vertical deck displacement to the riding comfort. The risk of derailment is estimated both as a wheel-unloading factor based on the filtered wheel-rail contact forces or as the duration of contact loss based on the unfiltered wheel-rail contact forces.A large set of theoretical bridges are studied, all optimised to reach the design limits according to EN 1990/A2 for either vertical bridge deck acceleration or displacement. The results show that there is no risk of derailment until the deck acceleration exceeds 30 m/s2. Based on the present parametric study, it appears that the current limit for vertical deck acceleration of non-ballasted railway bridges is very conservative but that the limits for vertical deck displacement is in the correct order of magnitude. It is further concluded that the magnitude of rail irregularities is of great importance, often causing larger dynamic response in the vehicle than due to the vibration of the bridge.
  •  
39.
  • Andersson, Andreas, et al. (författare)
  • Using eddy covariance to estimate air-sea gas transfer velocity for oxygen
  • 2016
  • Ingår i: Journal of Marine Systems. - : Elsevier. - 0924-7963 .- 1879-1573. ; 159, s. 67-75
  • Tidskriftsartikel (refereegranskat)abstract
    • Air-sea gas transfer velocity for O2 is calculated using directly measured fluxes with the eddy covariance technique. It is a direct method and is frequently used to determine fluxes of heat, humidity, and CO2, but has not previously been used to estimate transfer velocities for O2, using atmospheric eddy covariance data. The measured O2 fluxes are upward directed, in agreement with the measured air-sea gradient of the O-2 concentration, and opposite to the direction of the simultaneously measured CO2 fluxes. The transfer velocities estimated from measurements are compared with prominent wind speed parameterizations of the transfer velocity for CO2 and O2, previously established from various measurement techniques. Our result indicates stronger wind speed dependence for the transfer velocity of O2 compared to CO2 starting at intermediate wind speeds. This stronger wind speed dependence appears to coincide with the onset of whitecap formation in the flux footprint and the strong curvature of a cubic wind -dependent function for the transfer velocity provides the best fit to the data. Additional data using the measured O2 flux and an indirect method (based on the Photosynthetic Quotient) to estimate oxygen concentration in water, support the stronger wind dependence for the transfer velocity of O2 O-2 to CO2.
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40.
  •  
41.
  • Andersson, Christoph, 1956-, et al. (författare)
  • Nazisten som teg : Drömmen om att skapa högerextrema terrorceller i Tyskland och Sverige
  • 2017. - 3000
  • Bok (populärvet., debatt m.m.)abstract
    • Beate Zschäpe, 38, sitter i en domstol i München och tiger, iklädd en mörk businessdress och med håret utslaget. Det har hon gjort sedan 2013, åtalad för delaktighet i tio mord, flera bankrån och två bombattentat, begångna mellan 1999 och 2011. Här skulle också hennes kumpaner Uwe Mundlos och Uwe Böhnhardt ha suttit, men både hade dött under mystiska omständigheter 2011.Trion gick under namnet NSU, Nationalsozialisticher Untergrund. Målet var att bli en brun motsvarighet till RAF, Röda arméfraktionen, med Lasermannen John Ausonius som inspirationskälla. Men också svenska NRA, Nationella revolutionära armén Tony Olsson, Jackie Arklöv, Andreas Axelsson och andra militanta högerextremister i Sverige.Det här är berättelsen om trion och ett bakomliggande högerextremt nätverk, med förgreningar till Norden. Likaså om hur det indirekt stöddes av den tyska säkerhetspolisens Författningsskydd. Beate Zschäpe har goda skäl att tiga, men vill samtidigt gärna berätta om alla sina år i terrorcellen. Frågan är om hon ska våga ta bladet från munnen.
  •  
42.
  • Andersson, Charlotta, 1976- (författare)
  • Significance of Wilms’ tumor gene 1 as a biomarker in acute leukemia and solid tumors
  • 2016
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Wilms’ tumor gene 1 (WT1) is a zinc finger transcriptional regulator with crucial functions in embryonic development. Originally WT1 was described as a tumor suppressor gene, but later studies have shown oncogenic properties of WT1 in a variety of tumors. Because of its dual functions in tumorigenesis, WT1 has been described as a chameleon gene. In this thesis, the significance of WT1 as a biomarker was investigated in acute myeloid leukemia (AML), clear cell renal cell carcinoma (ccRCC), ovarian carcinoma (OC) and childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL).Previous studies have suggested that expression of WT1 is a potential marker for detection of minimal residual disease (MRD) in AML. We aimed to define expression of WT1 as an MRD marker in AML. In adult AML patients, we found that a reduction of WT1 expression in bone marrow (≥ 1-log) detected less than 1 month after diagnosis was associated with an improved overall survival (OS) and freedom from relapse (FFR). In peripheral blood, a reduction of WT1 expression (≥ 2-log) detected between 1 and 6 months after treatment initiation was associated with an improved OS and FFR.WT1 harbor pathogenic genetic variants in a considerable proportion of AML and T-lymphoblastic leukemia (T-ALL), but mutations have not been reported in BCP-ALL. We aimed to evaluate the clinical impact of WT1 mutations and single nucleotide polymorphisms (SNPs) in BCP-ALL. Pathogenic mutations in the WT1 gene were rarely seen in childhood BCP-ALL. However, five WT1 SNPs were identified. In survival analyses, WT1 SNP rs1799925 was found to be associated with worse OS, indicating that WT1 SNP rs1799925 may be a useful marker for clinical outcome in childhood BCP-ALL. We also explored whether WT1 mutations and SNPs in ccRCC could be used as biomarkers for risk and treatment stratification. We therefore examined whether SNPs or mutations in WT1 were associated with WT1 expression and clinical outcome. Sequencing analysis revealed that none of the previously reported WT1 mutations were found in ccRCC; however, we identified six different WT1 SNPs. Our data suggest that pathogenic WT1 mutations are not involved in ccRCC, and the prognostic significance of WT1 SNPs in ccRCC is considerably weak. However, a favorable OS and disease-specific survival were found in the few cases harboring the homozygous minor allele.OC has a poor prognosis, and early effective screening markers are lacking. Serous OCs are known to express the WT1 protein. Overexpressed oncogenic proteins can be considered potential candidate antigens for cancer vaccines and T-cell therapy. It was therefore of great interest to investigate whether anti-WT1 IgG antibody (Ab) measurements in plasma could serve as biomarkers of anti-OC response. We found limited prognostic impact, but the results indicated that anti-WT1 IgG Ab measurements in plasma and WT1 staining in tissue specimens could be potential biomarkers for patient outcome in the high-risk subtypes of OCs.In conclusion, the results of this thesis indicate that WT1 gene expression can provide information about MRD of patients with AML, and WT1 SNP rs1799925 may be used as a biomarker for predicting clinical outcome in childhood BCP-ALL. In ccRCC, the prognostic significance of WT1 SNPs is weak and limited to the subgroup of patients that are homozygous for the minor allele. In OCs anti-WT1 IgG Ab measurement in plasma and WT1 staining in tissue specimens could possibly be used as biomarkers for predicting patient outcome in the high-risk subtypes of OCs.
  •  
43.
  • Andersson, Dag, et al. (författare)
  • Smart access to small lot manufacturing for systems integration
  • 2018
  • Ingår i: 2018 Pan Pacific Microelectronics Symposium, Pan Pacific 2018. - 9781944543044 ; , s. 1-9
  • 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.
  •  
44.
  • Andersson, Dag, et al. (författare)
  • SMARTER-SI - Smart access to manufacturing for Systems Integration
  • 2017
  • 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.
  •  
45.
  • Andersson-Engels, Stefan, et al. (författare)
  • Deep-tissue optical imaging and photoactivation activities at biophotonics@tyndall
  • 2016
  • Ingår i: Frontiers in Optics, FiO 2016. - 2162-2701. - 9781943580194
  • Konferensbidrag (refereegranskat)abstract
    • Activities for deep tissue imaging and photoactivation will be presented. Wihin Biophotonics@Tyndall projects based on upconverting nanoparticles and ultrasound optical tomography will be pursued. Data from collaborative research will be given.
  •  
46.
  • Andersson, Fredrik, 1974-, et al. (författare)
  • Female top management in family firms and non-family firms : Evidence from total population data
  • 2018
  • Ingår i: International Journal of Entrepreneurship and Small Business. - : InderScience Publishers. - 1476-1297 .- 1741-8054. ; 35:3, s. 303-326
  • Tidskriftsartikel (refereegranskat)abstract
    • We exploit information on ownership, management and kinship to study the representation of women in top management teams in Swedish family and non-family firms among domiciled limited liability firms over the years 2004 to 2010. The share of female top managers is analysed across listed and non-listed firms as well as across industries. We then estimate the likelihood that a woman is elected into the top management team in family and non-family firms using a probit regression model where we control for firm- A nd individual-level characteristics, including the gender distribution of the firm and kinship relations to existing board members and firm owners. We find that non-listed family firms are more likely to appoint female top managers, whereas we find no differences among listed firms. Moreover, we find that the gender composition and kinship structures of firms influence the appointment of female top managers.
  •  
47.
  • Andersson, Fredrik N G, et al. (författare)
  • Sverige på väg mot en djup kris
  • 2016
  • Ingår i: Dagens Industri. - 0346-640X.
  • Tidskriftsartikel (populärvet., debatt m.m.)
  •  
48.
  • Andersson, Fredrik N G, et al. (författare)
  • Riksbanken feltolkar lagen i sin syn på inflationsmålet
  • 2016
  • Ingår i: Dagens nyheter (DN debatt). - 1101-2447. ; , s. 6-6
  • Tidskriftsartikel (populärvet., debatt m.m.)abstract
    • Mot lagens anda. Riksbanken tycks ha feltolkat sitt uppdrag. Riksbankslagen erbjuder flexibilitet, trots det håller Riksbanken fast vid 2-procentmålet till nästan vilket pris som helst. Dessutom bryter man mot lagens anda när man köper statsobligationer för mångmiljardbelopp, skriver Fredrik NG Andersson, Andreas Bergh och Anders Olshov.
  •  
49.
  • Andersson, Fredrik, 1974-, et al. (författare)
  • The Characteristics and Performance of Family Firms : Exploiting information on ownership, governance and kinship using total population data
  • 2017
  • Rapport (refereegranskat)abstract
    • Family firms are often considered characteristically different from non-family firms, and the economic implications of these differences have generated significant academic debate. However, our understanding of family firms suffers from an inability to identify them in total population data, as this requires information on owners, their kinship and involvement in firm governance, which is rarely available. We present a method for identifying domiciled family firms using register data that offers greater accuracy than previous methods. We then apply it to data from Statistics Sweden concerning firm ownership, governance and kinship over the years 2004-2010. Next, we use Swedish data to estimate these firms’ economic contribution to total employment and gross domestic product (GDP) and compare them to private domiciled non-family firms in terms of their characteristics and economic performance. We find that the family firm is the prevalent organizational form, contributing to over one-third of all employment and GDP. Family firms are common across industries and sizes, ranging from the smallest producers to the largest multinational firms. However, their characteristics differ across sizes and legal forms, thereby indicating that the seemingly contradictory findings among previous studies on family firms may be due to unobserved heterogeneity. We furthermore find that they are smaller than private non-family firms in employment and sales and carry higher solidity, although they are more profitable. These differences diminish with firm size, however. We conclude that the term ‘family firm’ contains great diversity and call for increased attention to their heterogeneity.
  •  
50.
  • Andersson, Fredrik, 1974-, et al. (författare)
  • The Characteristics of Family Firms : Exploiting Information on Ownership, Kinship and Governance Using Total Population Data
  • 2018
  • Ingår i: Small Business Economics. - : Kluwer Academic/Plenum Publishers. - 0921-898X .- 1573-0913. ; 51:3, s. 539-556
  • Tidskriftsartikel (refereegranskat)abstract
    • Family firms are often considered characteristically different from non-family firms. However, our understanding of family firms suffers from an inability to identify them in total population data; information is rarely available regarding owners, their kinship, and their involvement in firm governance. We present a method for identifying domiciled family firms using register data; this method offers greater accuracy than previous methods. We apply this method to Swedish data concerning firm ownership, governance, and kinship from 2004 to 2010. We find that the family firm is a significant organizational form, contributing over one third of all employment and gross domestic product (GDP). Family firms are common in most industries and range in size. Furthermore, we find that, compared to private non-family firms, family firms have fewer total assets, employment, and sales and carry higher solidity, although family firms are more profitable. These differences diminish with firm size. We conclude that the term “family firm” includes a large variety of firms, and we call for increased attention to their heterogeneity.
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