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QC 20201012

Background: The Arctic and subarctic area are likely to be highly affected by climate change, with possible impacts on human health due to effects on food security and infectious diseases. Objectives: To investigate the evidence for an association between climatic factors and infectious diseases, and to identify the most climate-sensitive diseases and vulnerable populations in the Arctic and subarctic region. Methods: A systematic review was conducted. A search was made in PubMed, with the last update in May 2013. Inclusion criteria included human cases of infectious disease as outcome, climate or weather factor as exposure, and Arctic or subarctic areas as study origin. Narrative reviews, case reports, and projection studies were excluded. Abstracts and selected full texts were read and evaluated by two independent readers. A data collection sheet and an adjusted version of the SIGN methodology checklist were used to assess the quality grade of each article. Results: In total, 1953 abstracts were initially found, of which finally 29 articles were included. Almost half of the studies were carried out in Canada (n = 14), the rest from Sweden (n = 6), Finland (n = 4), Norway (n = 2), Russia (n = 2), and Alaska, US (n = 1). Articles were analyzed by disease group: food-and waterborne diseases, vector-borne diseases, airborne viral-and airborne bacterial diseases. Strong evidence was found in our review for an association between climatic factors and food-and waterborne diseases. The scientific evidence for a link between climate and specific vector-and rodent-borne diseases was weak due to that only a few diseases being addressed in more than one publication, although several articles were of very high quality. Air temperature and humidity seem to be important climatic factors to investigate further for viral-and bacterial airborne diseases, but from our results no conclusion about a causal relationship could be drawn. Conclusions: More studies of high quality are needed to investigate the adverse health impacts of weather and climatic factors in the Arctic and subarctic region. No studies from Greenland or Iceland were found, and only a few from Siberia and Alaska. Disease and syndromic surveillance should be part of climate change adaptation measures in the Arctic and subarctic regions, with monitoring of extreme weather events known to pose a risk for certain infectious diseases implemented at the community level.

Run-of-mine ore is usually too large to be useful for construction or metallurgy. Large particles must be reduced to specific sizes to either comply with aggregate sizing regulations, or facilitate mineral liberation; therefore, in the aggregates and mineral processing industries, run-of-mine ore is broken in crushing circuits by cone crushers. Here, we review the cone crusher literature, focusing on the modeling and control of crushing circuits. A total of 61 works published in the primary literature, ranging from 1972 to 2020, are classified and discussed with respect to the model formulation—i.e., population balance models, empirical models, or data-driven models—and control strategy—i.e., proportional-integral-derivative, model predictive control, expert system, or model-free control. The data are summarized in a table that makes locating a particular formulation or strategy quick and easy. The discussion of the current state of the art of crushing circuit modeling and control technologies consolidates the results available in the literature, as well as the challenges that we must overcome to increase crushing performance through control and optimization. The discussion of future trends brings attention to the discrete element method, model based control, plant-wide and mine-to-mill optimization, and machine learning applications for data acquisition and process optimization. Validerad;2021;Nivå 2;2021-06-28 (beamah);Forskningsfinansiärer: Conselho Nacional de Desenvolvimento Científico e Tecnológico (Grant Nos. 402759/2018-4 and 444425/2018-7); Instituto Tecnológico Vale, Ouro Preto, Brazil; SAG Conference Award Foundation

This report is about a novel approach to attenuation of fan noise in aerial vehicles, by way of implementing a ducted fan in the chassis of a four meter blended wing body plane. Three different one meter PVC pipes were used and their performances as silencers were tested by measuring the sound power level and calculating the insulation loss compared to a fan by itself. The ducts were either empty or lined with acoustic absorbents and micro perforated panels. Experiments were carried out in the reverberation room at KTH Marcus Wallenberg laboratory for sound and vibration research using the guidelines in ISO 3741 (2010). The results showed that the empty duct lead to a 15.3 dB(A) insulation loss with no decrease in thrust from the fan. The absorbent and micro perforated panel, however, lead to a 22.7 dB(A) insulation loss while giving a major decrease in thrust of more than one order of magnitude. The results show the failure of implementation of the latter two silencers due to choking, but also the success of the empty duct. This shows that there is room for improvement and perhaps even a future possibility of a successful implementation in a real vehicle.

In der vorliegenden Arbeit wird die Berechnung der Festig-keit von dickwandigen Lochleibungslaminaten im Faserver-bundwerksto˙en unter dreidimensionalen Spannungszustän-den untersucht. Nichtlineare Materialverhalten von Hybrid-laminaten in CFK und GFK werden für Unidirektionalfa-serlagen und Gewebelagen berücksichtigt.Der Schwerpunkt liegt auf der Entwicklung von progressi-ven Versagensmodellen unter der Berüsichtigung von Rest-festigkeit und Reststeifigkeit des Materials. Zwei Modelli-erungsmethoden nach Puck-Kriterium zur Vorhersage des Versagens in UD-Lagen werden vorgeschlagen: eine Degra-dierungstechnik für ebene Spannungszustände und ein me-hrachsiges Modell.Numerische Simulationen mit der Finite-Elemente-Methode werden in Statik- und Ermüdungsanalyse an dickwandigen Lochleibungslaminaten unter einachsiger Belastung durch-geführt. Beschädigungen, Festigkeiten und Ermüdungsle-bensdauer werden dann mit experimentiellen Daten ver-glichen, um die numerischen Methoden zu validieren. The thesis deals with quasi-static and fatigue simulations of thick composite lugs subjected to three-dimensional stress states. This includes damage prediction of hybrid laminates made of GRFP and CRFP containing unidirectional and woven fabric plies.Focus lies on the development of a progressive damage model in fatigue which accounts for sti˙ness and strength degra-dations. Two methods based on Puck’s failure criterion are proposed to predict failure of unidirectional plies: one for plane stress analysis and and the other which takes out-of-plane damage into account.Virtual testing in FEM is conducted in quasi-static and fatigue analysis on thick composite lugs subjected to uni-axial loading. Damage, strength and life predictions are then compared with experimental results to validate the numerical models under investigations.

The monitoring of ammonium ion concentration has gained the attention of researchers from multiple fields since it is a crucial parameter with respect to environmental and biomedical applications. For example, ammonium is considered to be a quality indicator of natural waters as well as a potential biomarker of an enzymatic byproduct in key physiological reactions. Among the classical analytical methods used for the detection of ammonium ions, potentiometric ion-selective electrodes (ISEs) have attracted special attention in the scientific community because of their advantages such as cost-effectiveness, user-friendly features, and miniaturization ability, which facilitate easy portable measurements. Regarding the analytical performance, the key component of ISEs is the selective receptor, labelled as an ionophore in ISE jargon. Indeed, the preference of an ionophore for ammonium amongst other ions (i.e., selectivity) is a factor that primarily dictates the limit of detection of the electrode when performing measurements in real samples. A careful assessment of the literature for the last 20 years reveals that nonactin is by far the most employed ammonium ionophore to date. Despite the remarkable cross-interference of potassium over the ammonium response of nonactin-based ISEs, analytical applications comprising water quality assessment, clinical tests in biological fluids, and sweat monitoring during sports practice have been successfully researched. Nevertheless, there is evident difficulty in the determination of close-to-micromolar levels of ammonium in real samples with a significant potassium background level (i.e., millimolar concentration). This fact has fostered the search for a large variety of ammonium ionophores over the years, which are critically inspected herein. Overall, we provide an easily readable state of the art accompanied by a comprehensive description of other types of ammonium electrodes, including commercially available units. We conclude that newer breakthroughs are still required in the field to reach the desired analytical applications. QC 20211129

At the time of writing, in early May 2020, most architecture educators have passed through all five stages of the Kübler-Ross model of grief: denial, anger, depression, bargaining, acceptance (Kübler-Ross, 1969). We spent the first two months of the year in a politically-sanctioned period of denial. When it became apparent that the virus was not contained to a specific geographic region or demographic, our governments instigated restrictions and our universities closed. At that point, we entered the phase of anger. Some made it to bargaining and then depression. Those who made it out the other side are emerging with a lukewarm glow of acceptance: we are all distance educators now.

Programmering har en central roll i datavetenskapliga utbildningar. Många anser att programmering är svårt att lära sig. Ett stort antal studier har undersökt vad som orsakar dessa svårigheter och hur det är möjligt att övervinna dem. Denna avhandling är en del av denna forskning. Artiklarna i avhandlingen undersöker vilka problem som studenterna stöter på under sina programmeringsstudier. Artikel 1 beskriver hur studenter använder sig av annoteringar vid problemlösning. Resultaten visar att studenter som gör många annoteringar tenderar att prestera bättre. Resultaten antyder också att det kan finnas kulturella skillnader i hur ofta annoteringar används. Studenter har inte bara problem vid programmering, de har också problem med att utforma programvarusystem. Även sistaårsstudenter misslyckas till stor del att utforma lösningar för relativt enkla system. Resultaten i Artikel II visar att majoriteten av studenterna inte kommer längre än en omformulering av problemet. Att inte förstå ett koncept eller en specifik detalj är något som alla studenter stöter på då och då. I Artikel III undersöker vi hur framgångsrika studenter hanterar en sådan situation. Resultaten visar att studenterna använder sig av ett stort antal olika strategier för att få en förståelse för konceptet/detaljen. Många av de redovisade strategierna bygger på en social interaktion med andra. Artiklarna IV, V och VI utforskar vad studenterna uppfattar som nyckelkoncept inom datavetenskap och hur förståelsen av dessa koncept påverkar dem. Resultaten visar att förståelsen av vissa specifika koncept kan göra att studenterna ändrar hur de ser på datavetenskap, kollegor och sig själva. I artiklarna VII och VIII undersöker vi hur forskare, lärare och studenter ser på de problem studenter har vid jämlöpande programmering. De flesta forskare och lärare hävdar att studenterna har problem med att förstå icke-determinism, synkronisering, etc. Våra resultat visar dock att studenterna inte själva tycks anse att jämlöpande programmering är signifikant svårare än andra ämnen. Tvärtom, de flesta anser att jämlöpande programmering är både lätt att förstå och roligt. Programming is a core subject within Computer Science curricula and many also consider it a particularly difficult subject to learn. There have been many studies and suggestions on what causes these difficulties and what can be done to improve the situation. This thesis builds on previous work, trying to understand what difficulties students have when learning to program. The included papers cover several areas encountered when trying to learn programming. In Paper I we study how students use annotations during problem solving. The results show that students who annotate more also tend to be more successful. However, the results also indicate that there might be a cultural bias towards the use of annotations. Not only do students have problems with programming, they also have problems with designing software. Even graduating students fail to a large extent on simple design tasks. Our results in Paper II show that the majority of the students do not go beyond restating the problem when asked to design a system. Getting stuck is something that most learners experience at one time or another. In Paper III we investigate how successful students handle these situations. The results show that the students use a large number of different strategies to get unstuck and continue their learning. Many of the strategies involve social interaction with peers and others. In Papers IV, V, and VI we study what students experience as being key and threshold concepts in Computer Science. The results show that understanding particular concepts indeed affect the students greatly, changing the way they look at Computer Science, their peers, and themselves. The two last papers, Papers VII and VIII, investigate how researchers, teachers and students view concurrency. Most researchers/teachers claim that students have difficulties because of non-determinism, not understanding synchronization, etc. According to our results the students themselves do not seem to think that concurrency is significantly more difficult than any other subject. Actually most of them find concurrency to be both easy to understand and fun.

Autonomous driving technology is continuously evolving at an accelerated pace. The road environment is always uncertain, which requires an evasive manoeuvre that an autonomous vehicle can take. This evasive behaviour to avoid accidents in a critical situation is analogous to autonomous racing that operates at the limits of stable vehicle handling. In autonomous racing, the vehicle must operate in highly nonlinear operating conditions such as high-speed manoeuvre on sharp turns, avoiding obstacles and slippery road conditions. These dynamically changing racing situations require advanced path planning systems with obstacle avoidance executed in real-time. Therefore, the motion planning problem for autonomous racing is analogous to safe and reliable autonomous vehicle operation in critical situations. This thesis project evaluates the application of traction adaptive motion planning to autonomous racing on different road surfaces for a small-scale test vehicle in real-time. The evaluation is based on a state-of-the-art algorithm that uses a combination of optimization, trajectory rollout, and constraint adaption framework called "Sampling Augmented Real-Time Iteration (SAARTI)". SAARTI allows motion planning and control with respect to time-varying vehicle actuation capabilities while taking locally adaptive traction into account for different parts of the track as a constraint. Initially, the SAARTI framework is adapted to work with the SmallVehicles-for-Autonomy (SVEA) system; then, the whole system is simulated in a ROS (Robot Operating System) based SVEA simulator with a Hardware-in-the-loop setup. Later, the same setup is used for the real time experiments that are carried out using the SVEA vehicles, and the different critical scenarios are tested on the SVEA vehicle. The emphasis was given to the experimental results; therefore, the results also consider computationally intensive localization inputs while the motion planner was implemented in real-time instead of a simulation setup. The experimental results showed the impact of planning motions according to an approximately correct friction estimate when the friction parameter was close to the actual value. The results indicated that the traction variation had indeed affected the lap time and trajectory taken by the test vehicle. The lap time is affected significantly when the coefficient of friction value is far away from the real friction coefficient. It is observed that the lap time increased significantly at higher values of friction coefficient, when involving more excessive over-estimation of the traction, leading to the oscillatory motion and lane exits. Furthermore, the non-adaptive case scenario result shows that the test vehicle performed better when given friction parameter inputs to the algorithm approximately equal to the real friction value.  Teknik för autonom körning har utvecklats i snabb takt de senaste åren. Trafikmiljön innehåller många källor till osäkerhet, vilket ibland kräver undanmanövrar av det autonoma fordonet. Undanmanövrar i kritiska situationer är analoga med autonom racing i det avseendet att fordonet opererar nära gränsen av dess fysiska förmåga. I autonom racing måste fordonet fungera i hög grad olinjära driftsförhållanden som höghastighetsmanöver i skarpa svängar, undvika hinder och halt väglag. Dessa dynamiska föränderliga racingsituationer kräver avancerad vägplaneringssystem med undvikande av hinder exekveras i realtid. Därför är rörelseplaneringsproblemet för autonom racing är analogt med det för säkra undanmanövrer i kritiska situationer. Detta examensarbete utvärderar tillämpningen av dragkraft adaptiv till autonom racing på olika väglag för ett småskaligt testfordon i realtid. Utvärderingen baseras på en algoritm som kallas "Sampling Augmented Real Time Iteration (SAARTI)" som tillåter rörelse planering och kontroll med avseende på tidsvarierande fordonsdynamik, på så vis tar algoritmen hänsyn till lokalt varierande väglag. Arbetet började med att integrera SAARTI-ramverket med testplattformen Small-Vehicles-for-Autonomy (SVEA). Därefter utfördes hardware-in-the-loop simuleringar i ROS (Robot Operating System), och därefter utfördes fysiska tester med SVEA plattformen. Under experimenten kördes SAARTI-algoritmen parallellt med en beräkningsintensiv SLAM-algoritm för lokalisering. De experimentella resultaten visade att adaptiv rörelseplanering kan avhjälpa problemet med lokalt varierande väglag, givet att den uppskattade friktionsparametern är approximativt korrekt. Varvtiden påverkas negativt när friktionsskattningen avviker från den verkliga friktionskoefficienten. Vidare observerades att varvtiden ökade vid höga värden på den skattade friktionsparametern, vilket gav upphov till mer aggressiva manövrer, vilket i sin tur gav upphov till oscillerande rörelser och avåkningar. 

Over the past quarter century, environmental DNA (eDNA) has been ascendant as a tool to detect, measure, and monitor biodiversity (species and communities), as a means of elucidating biological interaction networks, and as a window into understanding past patterns of biodiversity. However, only recently has the potential of eDNA been realized in the botanical world. Here we synthesize the state of eDNA applications in botanical systems with emphases on aquatic, ancient, contemporary sediment, and airborne systems, and focusing on both single-species approaches and multispecies community metabarcoding. Further, we describe how abiotic and biotic factors, taxonomic resolution, primer choice, spatiotemporal scales, and relative abundance influence the utilization and interpretation of airborne eDNA results. Lastly, we explore several areas and opportunities for further development of eDNA tools for plants, advancing our knowledge and understanding of the efficacy, utility, and cost-effectiveness, and ultimately facilitating increased adoption of eDNA analyses in botanical systems.