大気中エアロゾルの水抽出画分およびガスの水溶性画分におけるヒドロキシルラジカルの光化学的生成速度に関する研究

広島大学(Hiroshima University)博士(学術)Doctor of Philosophydoctora

Rain rendering for evaluating and improving robustness to bad weather

Rain fills the atmosphere with water particles, which breaks the common assumption that light travels unaltered from the scene to the camera. While it is well-known that rain affects computer vision algorithms, quantifying its impact is difficult. In this context, we present a rain rendering pipeline that enables the systematic evaluation of common computer vision algorithms to controlled amounts of rain. We present three different ways to add synthetic rain to existing images datasets: completely physic-based; completely data-driven; and a combination of both. The physic-based rain augmentation combines a physical particle simulator and accurate rain photometric modeling. We validate our rendering methods with a user study, demonstrating our rain is judged as much as 73% more realistic than the state-of-theart. Using our generated rain-augmented KITTI, Cityscapes, and nuScenes datasets, we conduct a thorough evaluation of object detection, semantic segmentation, and depth estimation algorithms and show that their performance decreases in degraded weather, on the order of 15% for object detection, 60% for semantic segmentation, and 6-fold increase in depth estimation error. Finetuning on our augmented synthetic data results in improvements of 21% on object detection, 37% on semantic segmentation, and 8% on depth estimation.Comment: 19 pages, 19 figures, IJCV 2020 preprint. arXiv admin note: text overlap with arXiv:1908.1033

Helicopter flights with night-vision goggles: Human factors aspects

Night-vision goggles (NVGs) and, in particular, the advanced, helmet-mounted Aviators Night-Vision-Imaging System (ANVIS) allows helicopter pilots to perform low-level flight at night. It consists of light intensifier tubes which amplify low-intensity ambient illumination (star and moon light) and an optical system which together produce a bright image of the scene. However, these NVGs do not turn night into day, and, while they may often provide significant advantages over unaided night flight, they may also result in visual fatigue, high workload, and safety hazards. These problems reflect both system limitations and human-factors issues. A brief description of the technical characteristics of NVGs and of human night-vision capabilities is followed by a description and analysis of specific perceptual problems which occur with the use of NVGs in flight. Some of the issues addressed include: limitations imposed by a restricted field of view; problems related to binocular rivalry; the consequences of inappropriate focusing of the eye; the effects of ambient illumination levels and of various types of terrain on image quality; difficulties in distance and slope estimation; effects of dazzling; and visual fatigue and superimposed symbology. These issues are described and analyzed in terms of their possible consequences on helicopter pilot performance. The additional influence of individual differences among pilots is emphasized. Thermal imaging systems (forward looking infrared (FLIR)) are described briefly and compared to light intensifier systems (NVGs). Many of the phenomena which are described are not readily understood. More research is required to better understand the human-factors problems created by the use of NVGs and other night-vision aids, to enhance system design, and to improve training methods and simulation techniques

Vision for Scene Understanding

This manuscript covers my recent research on vision algorithms for scene understanding, articulated in 3 research axes: 3D Vision, Weakly supervised vision, and Vision and physics. At the core of the most recent works is weakly-supervised learning and physics-embodied vision, which address short comings of supervised learning that requires large amount of data. The use of more physically grounded algorithms appears evidently beneficial as both robots and humans naturally evolve in a 3D physical world. On the other hand, accounting for physics knowledge reflects important cue about lighting and weather conditions of the scene central in my work. Physics-informed machine learning is not only beneficial for increased interpretability but also to compensate labels and data scarcity

Effekten av frysing og tining på vanntransport og utlekking av plantevernmidler i delvis frossen jord – Kolonnestudier og modellutvikling

Increased pesticide concentrations have often been detected in soil leachate, drain discharge and surface runoff during freeze/thaw periods in late winter and early spring, both in Norway and Sweden. Limited knowledge and experimental data exist however on pesticide leaching through partially frozen soil, partly because of the complexity of the processes involved. Climate changes can add to this complexity and influence the use and the fate and behaviour of pesticides. Models that can capture this complexity may help us improve our understanding of the systems and enable more reliable predictions of the transport of pesticides in partially frozen soil and of the potential impacts climate changes may have on water quality. One of the objectives of this PhD project has been to generate new knowledge and hence be able to increase the understanding of the complex processes of freezing and thawing and the effects these processes have on water flow and on the transport of bromide and pesticides. A second objective has been to develop and evaluate a dual-permeability approach for water flow and heat transport in macroporous soils undergoing freezing and thawing. To achieve these objectives we have conducted a soil column irrigation experiment to quantify the transport of a non-reactive tracer (bromide) and five pesticides (MCPA, clomazone, boscalid, propiconazole, diflufenican) in partially frozen soil. Intact topsoil and subsoil columns (i.d. 9.2 cm, h 20 cm) from two agricultural soils (silt and loam) in South-East Norway were sampled and bromide and pesticides were applied on top of all columns. Half the columns were then frozen (-3 °C) while the other half were left unfrozen (+4 C). Columns were subjected to repeated irrigation events which were followed by periods of freezing or refrigeration. Leachate from the columns was collected and analysed for pesticides and bromide. Parallel to this, physically based equations for soil freezing and thawing was included in the MACRO model. We tested the new model for water flow in the micropore domain against available measured data on the redistribution of water during freezing and illustrative scenario simulations were performed to demonstrate the effects of soil macropores on water flow and heat transport in partially frozen soils. The column study generated a substantial dataset which showed that pesticide leaching was up to five orders of magnitude larger from frozen than unfrozen columns. Leaching patterns of bromide and pesticides were very similar in most frozen columns with early breakthrough of high concentrations indicating preferential transport of the pesticides. Only very small amounts of pesticides leached from unfrozen topsoil columns. In the unfrozen columns, bromide showed a more uniform advective-dispersive transport process without clear concentration peaks. The rank order in pesticide leaching observed corresponded to the rank order of mean Kf values for the pesticides suggesting that sorption plays a role in determining leaching losses even in frozen soil. There were indications though that this was most important for pesticides of intermediate mobility. In the modelling part of the project, several test cases were performed to test the model. Compared to the limited number of existing models and datasets, the new version of MACRO simulated the redistribution of water in the micropore domain during freezing equally well. When comparing the First Order Energy Transfer (FOET) approach with the heat flow equation, energy exchange and average temperatures were reproduced well when running without the freezing model. When running the simulation with the freezing model, similarly good fits was not observed but as the FOET approach is an approximation, a perfect fit was not expected. When looking at the water flow in macropores during freezing, the results of the simulations were in line with both our perception of the processes as well as the limited data that exists on water flow through macropores. In the last test case, the complete model was evaluated by simulating thawing from the soil surface of an initially frozen soil column (h 20 cm) during a constant rainfall of 1.5 mm h-1. This test showed that the model simulated the processes according to our expectations and the theory with regards to the energy transfer between the pore domains and how this affected the freezing and melting of water in macropores and micropores and the infiltration and percolation of water. In several respects the model results were similar to observations made in the soil column studies.  Høye konsentrasjoner av plantevernmidler er observert i sigevann, drensvann og overflateavrenning fra jord i perioder med frysing/tining sent om vinteren eller tidlig om våren i områder med kaldt klima. Det er begrenset med kunnskap og lite eksperimentelle data på dette med transport av plantevernmidler gjennom frossen jord, noe som bl.a. skyldes at de aktuelle prosessene og mekanismene er veldig komplekse. Klimaendringene kan øke denne kompleksiteten ytterligere og påvirke både bruken av og skjebnen til plantevernmidlene. Datamodeller kan beskrive denne kompleksiteten og hjelpe oss med å forstå det som skjer på en bedre måte slik at vi kan forutsi hvordan plantevernmidler vil transporteres i frossen jord og hvordan klimaendringer kan virke inn på vannkvaliteten. En av målsetningene med dette PhD-prosjektet har vært å fremskaffe ny kunnskap slik at vi kan forstå mer av de kompliserte fryse-tine prosessene i jord og effektene disse prosessene har på transporten av vann og plantevernmidler. En annen målsetning har vært å utvikle og evaluere en modell for utveksling og transport av vann og varmeenergi i og mellom makro og mikroporer i jord som utsettes for frysing og tining. For å kunne nå disse målsetningene satte vi i gang et søyleforsøk for å kvantifisere transporten av et ikke-reaktivt sporstoff (bromid) og fem ulike plantevernmidler (MCPA, clomazone, boscalid, propiconazole og diflufenican) i delvis frossen jord. Vi samlet inn intakte jordsøyler av toppjord og undergrunnsjord fra to ulike typer landbruksjord (silt og lettleire) i Sørøst-Norge. Bromid og plantevernmidler ble så tilsatt på overflaten av alle søylene. Halvparten av søylene ble frosset (-3 °C), mens de resterende ble satt på kjølerom (+4 °C). Søylene ble så utsatt for gjentagende vanninger som ble etterfulgt av frysing/kjøling. Sigevann fra søylene ble samlet opp og analysert for bromid og plantevernmidler. Parallelt med dette er matematiske funksjoner for frysing og tining lagt inn i modellen MACRO. Vi har testet og evaluert den nye modellen og undersøkt hvordan den modellerer vanntransporten i mikroporene og sammenlignet dette med tilgjengelige målte data på omfordelingen av vann i jord som fryser. I tillegg har vi utført simuleringer som illustrerer hvordan tilstedeværelsen av makroporer påvirker vann- og varmeenergitransporten i delvis frossen jord. Resultatene av søyleforsøket viste at opptil 5000 ganger mer plantevernmidler ble transportert ut av de frosne søylene enn fra de ikke-frosne søylene. Transportmønsteret for bromid og plantevernmidler var ganske likt i de frosne søylene, med høye konsentrasjoner som lekket ut av søylene relativt kort tid etter at vanning ble igangsatt og lite vann hadde gått gjennom søylene. Dette indikerte at transporten foregikk gjennom større kanaler i jorda. Kun små mengder plantevernmidler ble transportert ut av de søylene som ikke var fryste, mens bromid viste en mer enhetlig transport, dvs at transporten skjedde gjennom hele jordprofilet uten å gi de samme konsentrasjonstoppene man så i sigevann fra de fryste søylene. Rekkefølgen mellom de ulike plantevernmidlene i forhold til mengden som lekket ut falt sammen med bindingsegenskapene de enkelte stoffene har i jord. Dette viste at bindingsegenskapene også har en betydning i frossen jord, selv om det var tegn som tydet på at dette betydde mer for plantevernmidler med medium bindingsegenskaper enn for mer mobile stoffer eller stoffer som vanligvis binder seg sterkere i jord. I modell-delen av prosjektet ble det utført flere tester av den nye modellen. Sammenlignet med det begrensede antall eksisterende modeller og datasett, simulerte den nye versjonen av MACRO omfordeling av vann i mikropore-domenet under frysing veldig bra. Ved sammenligning av FOET-modellen ble energiutveksling og gjennomsnittstemperaturer gjengitt godt når modellen kjørte uten frysing. Ved simulering med frysing var ikke tilpasningen like god, men da FOET-modellen er en tilnærming, var det heller ikke forventet at tilnærmingen skulle bli perfekt. Når vi så på vannstrømmen i makroporene under frysing, var resultatene av simuleringene i tråd med både vår oppfatning av prosessene og de begrensede dataene som eksisterer på området. I den siste testen ble den komplette modellen evaluert ved å simulere tining fra jordoverflaten av en opprinnelig frosset jordkolonne (h 20 cm) med konstant nedbør på 1,5 mm h-1. Denne testen viste at modellen simulerte prosessene i stor grad i henhold til våre forventninger og den generelle teorien, spesielt med hensyn til energioverføringen mellom poredomenene og hvordan dette påvirket frysing og tining av vann i makro- og mikroporer samt infiltrasjon og utlekking av vann. Modellresultatene stemte i flere tilfeller overens med observasjoner gjort i kolonnestudiene og teorien rundt observasjonene