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This work aims to validate numerical modelling of water sprays against experiments carried out in this project. The focus has been on the influence of ventilation on water distributions on the tunnel floor, the influence of water sprays on control of smoke flow, and the modelling of pool fires and crib fires. Besides, full scale tunnel fires with FFFS in tunnels using longitudinal ventilation and point extraction ventilation systems are simulated and compared, as well recommendations for numerical modelling of such scenarios., The work is a part of the project “Mechanisms and performance of different fixed fire fighting systems (FFFS) in tunnels” funded by Swedish Research Council FORMAS (2019-00521), which is gratefully acknowledged.

There is a vast literature evaluating the empirical association between stay-at-home policies and crime during the COVID-19 pandemic. However, these academic efforts have primarily focused on the effects within specific cities or regions rather than adopting a cross-national comparative approach. Moreover, this body of literature not only generally lacks causal estimates but also has overlooked possible heterogeneities across different levels of stringency in mobility restrictions. This paper exploits the spatial and temporal variation of government responses to the pandemic in 45 cities across five continents to identify the causal impact of strict lockdown policies on the number of offenses reported to local police. We find that cities that implemented strict lockdowns experienced larger declines in some crime types (robbery, burglary, vehicle theft) but not others (assault, theft, homicide). This decline in crime rates attributed to more stringent policy responses represents only a small proportion of the effects documented in the literature.

The study examines whether school-level immigrant concentration is related to students' involvement in violence, and whether students' moral values moderate the relationship between immigrant concentration and violence. The study is based on six nationally representative school surveys conducted by the Swedish National Council for Crime Prevention between 1999 and 2011, with a combined sample of 38,711 adolescents. We have combined different surveys to create one large pooled data set to evaluate segregation effects at the school level. Multilevel linear probability models are used to examine cross-level interaction effects. This study shows that contextual effects impact students differently, and that the relationship between immigrant concentration and violence is considerably stronger for adolescents with weak personal moral values. The paper provides empirical support for the differential vulnerability hypothesis. Policy and practice would benefit from a focus on the further development of programs and interventions that target personal moral values, not least in schools.

This study examines whether unstructured and structured activities interact in their association with delinquency and cannabis use. We hypothesize that unstructured activities are more strongly associated with delinquency and cannabis use for those who are less engaged in structured activities. Data are drawn from three nationally representative self-report studies conducted between 2005 and 2011 in Sweden, and include 19,644 adolescents. The results support the hypothesis that unstructured activities interact with structured activities in the association with delinquency and cannabis use. The association between unstructured activities and these outcomes is stronger for those with lower levels of structured activities. Sporting activities constitute the structured activity that most clearly interacts with unstructured activities in the association with delinquency and cannabis use.

OBJECTIVES: This study examines the associations between ten family structure types and delinquency, including four groups of symmetrical and asymmetrical living arrangements. We also adjust for attachment to parents and parental monitoring. METHODS: Data are drawn from four cross-sectional surveys conducted between 2016 and 2019 in southern Sweden. The sample consists of 3,838 adolescents, aged 14-15. Negative binomial models were used to calculate the associations between family structure and delinquency. RESULTS: The results show that those living in single-father, single-mother, father-stepmother, mother-stepfather families report significantly more delinquency than adolescents living with both their parents. Adolescents living in "symmetrical" family arrangements, i.e. both parents are single or have a new partner, reported lower levels of delinquency, whereas adolescents living in "asymmetrical" family arrangements, i.e. where either the mother or the father, but not both, have a new partner, reported higher levels of delinquency. Most of the associations between family structure and delinquency decline when adjusted for attachment to parents and parental monitoring. DISCUSSION: This study shows that it is important to move on to the use of more detailed categorisations of family structure in relation to delinquency. We need to increase our knowledge about the group of adolescents that moves between parents and especially about the different constellations of asymmetrical and symmetrical living arrangements.

Syftet med denna kvalitativa studie har varit att utveckla kunskaper om hur filosofiska frågor i det naturvetenskapliga klassrummet påverkar elevers kommunikativa förmåga att argumentera och ta ställning. Frågeställningarna som använts för att möjliggöra studien är: På vilka sätt argumenterar elever i mötet med filosofiska frågor av naturvetenskaplig karaktär? Hur kan filosofiska frågor användas som resurs i det naturvetenskapliga klassrummet för att gynna elevers kommunikativa förmåga att argumentera och ta ställning inom naturvetenskap? Studien genomfördes vid en skola i norra Sverige och bestod av 13 deltagare från årskurserna 3-6 som deltog vid fyra undervisningstillfällen. Undervisningstillfällena bestod av utredning av filosofiska frågor med naturvetenskaplig karaktär i samtalsgrupper där en filosofisk samtalsstruktur följdes. Tillfällena observerades och data samlades in med hjälp av video– och ljudinspelning samt loggboksanteckningar. Resultatet visade att eleverna argumenterade utifrån följande kategorier i mötet med lektionsinnehållet: Nyttoargument, etiska argument, estetiska argument, hållbarhetsargument och relevansargument. Vidare visade studiens resultat att faktorer som struktur, lärarstöd, elevstöd och metaforer var viktiga för eleverna i mötet med filosofiska frågor av naturvetenskaplig karaktär. Sammanfattningsvis visade denna studie att elevernas argumentationer och ställningstagande kan påverkas i positiv bemärkelse vid arbete med filosofiska frågor av naturvetenskaplig karaktär., The purpose of this qualitative study was to develop knowledge about how philosophical questions in the science classroom affects students' communicative ability to argue and to take positioning in a dilemma. The issues this study used to enable the study was: In what ways do students argue in the encounter with philosophical questions of a scientific nature? How can philosophical questions be used as a resource in the science classroom to benefit students' communicative ability to argue and take positioning in science? The study was implemented at a school in northern Sweden and consisted of 13 participants from the grades 3-6 who participated in four teaching opportunities. The teaching opportunities consisted of a philosophical inquiry of science questions in conversation groups where a philosophical conversation structure was followed. The teaching opportunities were observed and data was collected with the aid of video– and sound recording and logbook notes. Results show that students argued from the following categories: Utility argument, ethical arguments, aesthetic arguments, sustain arguments and relevance arguments. The result further showed that factors like: structure, teacher support, student support and metaphors were of importance to the students in their meeting with philosophical questions of a scientific nature. In summary, this study showed that students' arguments and positioning can be affected in positive meaning by using philosophical questions with scientific nature.

BAE Systems Hägglunds in Ornsköldsvik is an engineering company that producesoff-road and combat vehicles for military and civilian purposes and sees a need fordigital transformation and streamlining of production in order to maintain contractualdelivery times and be an employer of the future. The purpose of this thesis was to investigate a way to facilitate and streamline theorder card handling of a laser machine at the manufacturing site in Örnsköldsvik,where the reporting of orders is expected to become a bottleneck in production.The company’s believe in the future importance of digital transformation also wasa significant factor leading to the current work. As of today, order card handling in production is performed manually with physicaldocuments and drawings that follow through the production lines, from article toarticle, from cut-out raw material to finished detail. In this work, a concept hasbeen created, which simplifies the documentation of the production. The final concept meets the requirement for simpler reporting by (1) using a QuickResponse (QR) code and (2) by inserting an image of the article produced on theproduction card, thereby providing an overview of the articles that are simultaneouslycut in the laser machine. The QR-code is linked to additional reporting in thebusiness system for each work center, which, thus, constitutes a first step towardsdigital order cards in production., BAE Systems AB i Örnsköldsvik är ett verkstadsföretag som producerar terräng och stridsfordon för militära och civila ändamål och ser behov av digitalisering och effektivisering av produktionen för att bättre hålla avtalsbunda leveranstider och vara en arbetsgivare för framtiden. Syftet med examensarbetet var att undersöka ett sätt att underlätta och effektivisera orderkortshanteringen för en lasermaskin på tillverkningscite i Örnsköldsvik, där avrapporteringen av order väntas bli en flaskhals i produktionen. Företagets tro på digitalisering är även den en betydande faktor för examensarbetets uppkomst. Orderkortshanteringen i produktionen sker idag manuellt med fysiska dokument och ritningar som följer med genom produktionslinorna, från artikeln till artikel, från utskuret råmaterial till färdig detalj. Genom en strukturerad processutveckling, där beprövade metoder har använts för att identifiera krav och generera utkast, har ett koncept skapats för en förenkling av produktionsdokumentationen. Det slutliga konceptet uppfyller kravet om enklare avrapportering genom en Quick Response (QR) kod, och ger en snabb överblick över artiklarna som skärs i lasermaskinen samtidigt genom att visa en bild på en färdig artikel på produktionskortet. QR-koden är kopplad till avrapportering i affärssystemet för varje workcenter, vilket är ett första steg mot digitalisering av orderkorten i produktionen.

The ignition of natural fuels by sparks from strikes between metals and hard rock is far from understood and the ignition potential of sparks from rock strikes during heavy machinery operations is disputed in the scientific literature. This study utilises a spectrally resolved technique to study the temperature evolution of metal sparks from rock strikes. The study shows that initial temperature after collision can easily reach 1500 °C and this temperature can increase additionally by several hundred degrees as rapid oxidation processes are initiated, often leading to further disintegration of the fragment. The average temperature of fragments from such collisions is here measured to 1400 – 2000 °C and the combination of temperature, size and exothermic processes makes them viable for forest litter igniting. However, ignition on forest lands is always an unlikely, although possible outcome of heavy machinery operations and should be considered in risk assessment of the activity.