Particle-based likelihood inference in partially observed diffusion processes using generalised Poisson estimators

This paper concerns the use of the expectation-maximisation (EM) algorithm for inference in partially observed diffusion processes. In this context, a well known problem is that all except a few diffusion processes lack closed-form expressions of the transition densities. Thus, in order to estimate efficiently the EM intermediate quantity we construct, using novel techniques for unbiased estimation of diffusion transition densities, a random weight fixed-lag auxiliary particle smoother, which avoids the well known problem of particle trajectory degeneracy in the smoothing mode. The estimator is justified theoretically and demonstrated on a simulated example

multi scale urban flood forecasting muffin

A flooding event may be generally divided into the following three temporal stages, during which different users require different types of information.(1) Before the flood: The main components in this stage are the rainfall and flood forecasts, signaling when and where problems may occur. (2) During the flood: Frequent real-time observations are required to follow how the event develops and maximize situation awareness. (3) After the flood: Properly quality controlled, stored and documented observations, forecasts and other relevant information are needed to facilitate post-event analyses. However, this division is not straight-forward. For example, real-time observations (during the flood) can be important before the flood and forecasts (before the flood) can be important during the flood. Further, flood-related information (observations, forecasts) is available from systems operating over three different spatial domains. (1)The city: A city may operate its own flood forecasting system or be included in a small regional system.(2)The region/country: Several regions and countries operate forecasting systems.(3) The continent (Europe): A range of hydrological modelling systems have been set up for flood forecasting at the Pan-European level. Generally, local systems and information provide the highest value for the end-users in all flood phases. These systems may be based on highly detailed data on catchment characteristics (surface and sub-surface) and use hydraulic equations to describe local water fluxes. However, local systems are lacking in many cities which are thus dependent on purely hydrological information from national or even continental level. Today, this information is often too coarse in both time and space for being of real use in an urban context but this may change as the resolution, quality and availability of both meteorological and geographical data are rapidly increasing. In MUFFIN, the aim was to increase the end-user value of information related to urban floods by research and development at all scales as well as adaptation and promotion of existing material. The research and development have been performed in two cities: Aalborg (DK) and Helsinki (FI). During the first phase of the project, local forecasting systems were developed and optimized for selected sub-basins in these cities. In parallel, the hydrological model HYPE (http://hypeweb.smhi.se/) was developed for high-resolution modelling and set up for the same sub-basins. In the second phase of the project, coordinated forecasting experiments was carried out in order to explore the benefits and limitations of each type of model system as well as the prospect of combining them

Characterization of a Zeeman Slower Designed for a 87 Sr Optical Clock

Optical clocks will potentially become the new frequency standard for the SI-definition of the second. Many national metrology institutes around the world have already implemented different versions of such clocks and others are in process of doing so. At SP Technical Research Institute of Sweden, this process has recently begun. This thesis investigates the properties of the Zeeman slower that is to be used as part of the clock. A simple Gaussmeter was constructed from a semiconductor Hall sensor and used to measure the magnetic field profile of the slower. This report also contains the design for an electronic control circuit based on the Arduino platform, which can be used to control the magnetic field. The results showed that the particular slower investigated here will likely not need a control circuit. However, the control circuit can be used in other optical clocks or even in other applications.Mot ökad tidsnoggrannhet i Sverige Atomur baserade på mikrovågor är i dag den teknik som används för tidshållning. Snart kan detta komma att förändras i och med optiska klockor. Dessa klockor har bland annat potential att kunna förbättra satellitbaserade navigeringssystem som GPS och har en så hög noggrannhet att det öppnar upp nya möjligheter för forskning kring gravitation. En klocka är fundamental för tidsmätning. I sitt enklaste utförande är en klocka ett periodiskt fenomen, kombinerat med en enhet som räknar varje gång perioden upprepas från en given startpunkt. Det första kallas ofta för resonator och det andra helt enkelt för räknare. Denna enkla uppsättning kan dela in tid i mindre delar baserat på periodtiden hos resonatorn. Genom att öka dess frekvens så kan tiden delas i mindre delar. Det första atomuret som var noggrannare än andra klocktekniker byggdes 1955 vid National Physics Laboratory i Storbritannien. Denna klocka var baserad på mikrovågsstrålning från cesium. Den nuvarande definitionen av sekunden baseras på 9192631770 (ungefär 9,2 GHz) svängningar av den här strålningen. Om man kunde resa tillbaka fem miljoner år, till tiden då människan började separeras från aporna, och starta en cesiumklocka så skulle den endast visa en sekund fel idag. De senaste 30 åren har flera stora tekniska framsteg skett som har lett till nya tekniker för att ytterligare förbättra noggrannheten hos atomuren. De två viktigaste framgångarna kom med laserkylning av atomer och den så kallade frekvenskammen. Laserkylning har gjort det möjligt att kyla atomer, i princip, till absoluta nollpunkten. Detta medför att atomerna knappt rör sig och deras frekvens kan bestämmas ännu noggrannare. Frekvenskammen har öppnat upp för en helt ny typ av optiska atomur. De nya optiska klockorna baseras på atomernas optiska strålning istället för mikrovågsstrålningen, och "tickar" således flera storleksordningar snabbare (typiskt kring 500 THz) än dagens cesiumklockor. Skulle en optisk klocka startas samtidigt som big bang för 14 miljarder år sedan skulle den inte ens visa en sekund fel idag. Den optiska klocka som skall byggas vid SP Sveriges Tekniska Forskningsinstitut kommer vara baserad på strontium. Det arbete som har dokumenterats i den här uppsaten rör utvärdering av prestandan hos den del av laserkylningssystemet som kallas för "Zeeman slower". Denna del fungerar som ett första steg i nedkylningen av atomerna innan tidsmätningen kan på börjas. Projektet innehöll även design och konstruktion av en prototypkrets för elektronisk styrning av Zeeman slowern. Resultaten visade att utrustningen var väl anpassad för uppgiften och att styrkretsen troligtvis inte kommer behövas för god prestanda

Species-specific forest variable estimation using non-parametric modeling of multi-spectral photogrammetric point cloud data

The recent development in software for automatic photogrammetric processing of multispectral aerial imagery, and the growing nation-wide availability of Digital Elevation Model (DEM) data, are about to revolutionize data capture for forest management planning in Scandinavia. Using only already available aerial imagery and ALS-assessed DEM data, raster estimates of the forest variables mean tree height, basal area, total stem volume, and species-specific stem volumes were produced and evaluated. The study was conducted at a coniferous hemi-boreal test site in southern Sweden (lat. 58° N, long. 13° E). Digital aerial images from the Zeiss/Intergraph Digital Mapping Camera system were used to produce 3D point-cloud data with spectral information. Metrics were calculated for 696 field plots (10 m radius) from point-cloud data and used in k-MSN to estimate forest variables. For these stands, the tree height ranged from 1.4 to 33.0 m (18.1 m mean), stem volume from 0 to 829 m3 ha-1 (249 m3 ha-1 mean) and basal area from 0 to 62.2 m2 ha-1 (26.1 m2 ha-1 mean), with mean stand size of 2.8 ha. Estimates made using digital aerial images corresponding to the standard acquisition of the Swedish National Land Survey (Lantmäteriet) showed RMSEs (in percent of the surveyed stand mean) of 7.5% for tree height, 11.4% for basal area, 13.2% for total stem volume, 90.6% for pine stem volume, 26.4 for spruce stem volume, and 72.6% for deciduous stem volume. The results imply that photogrammetric matching of digital aerial images has significant potential for operational use in forestry

‘One of the most important questions that human beings have to understand’: Salafism as Islamic deferentialist fundamentalism

In the present article, the authors argue that the study of Salafism as a contemporary Islamic new religious movement could benefit from an analytical perspective separating fundamentalism into the modes of inferentialism and deferentialism. The basics of these concepts are outlined and discussed in relation to different aspects of contemporary Salafism as well as in relation to previous tendencies in Islamic history. As a case study, the authors employ the concept in an analysis of a contemporary Swedish Salafi discourse on the ‘wiping of the (leather) socks’ in the context of ritual purity. The authors argue that the concept of ‘deferential fundamentalism’ has a potential in the study of Salafism in that it allows for comparative analysis, both cross-religiously and diachronically, in contextualising Salafism historically. It also allows for an analysis of Salafi thought and practice in relation to theories of how human beings in general process social information

Real-time Implementation of a Novel Safety Function for Prevention of Loss of Vehicle Control

We present a novel safety function for prevention of vehicle control loss. The safety function overcomes some of the limitations of conventional Electronic Stability Control (ESC) systems. Based on sensor information about the host vehicle's state and the road ahead, a threat assessment algorithm predicts the future evolution of the vehicle's state. If the vehicle motion, predicted over a finite time horizon violates safety constraints, autonomous deceleration is activated in order to prevent vehicle loss of control. The safety function has been implemented in real-time. Experimental results indicate that the safety function relies less on the driver's skills than conventional ESC systems and that a more controllable and comfortable vehicle motion can be acquired when the function is active

Solanaceae in medicine and folklore : a literature review of the historical and contemporary uses

I växtfamiljen Solanaceae ingår en rad giftiga växter. Några av dessa arter har spelat viktiga historiska roller, som berusningsmedel, läkemedel och heliga växter. I denna rapport behandlas alruna (Mandragora officinarum), belladonna (Atropa belladonna), bolmört (Hyoscyamus niger) och spikklubbor (Datura spp.). Dessa växter har mycket liknande ämnessammansättning, vilket har lett till liknande användning runt om i världen. Många kunniga farmaceuter har hittat relevanta medicinska användningsområden för växterna genom historien, främst som smärt- och spasm-dämpande medel. Andra har hittat religiösa användningsområden för dem, som hallucinogener och religiösa symboler. De så kallade häxorna, sägs ha använt vissa av dessa växter, bland annat till de beryktade flygsalvorna. Det medicinska användandet av de aktiva ämnen växterna innehåller, fortsätter än idag. Dagens läkare använder i många fall ämnena på samma sätt man gjorde för ca 2000 år sedan.The plant family Solanaceae contain several poisonous plants. Some of these species has played a major role in history, as hallucinogens, medicinal plants and holy plants. This paper examines the species mandrake (Mandragora officinarum), belladonna (Atropa belladonna), henbane (Hyoscyamus niger) and thornapples (Datura spp.). The chemical constituents of these plants are very much the same, which has led to similar uses troughout the world. Many historical pharmacists have found use for these plants in medicine, mostly as pain and spasm relievers. Some people have found religious uses for the plants, as hallucinogens and religious symbols. The so-called witches may have used some of the species in flying ointments. The medicinal properties of the active constituents of these plants are still used in modern medicine. Modern pharmacists often use the constituents the same way as the historical pharmacists did around 2000 years ago

The significance of the stubble height for the mechanical spillage during forage harvesting

Vall odlas vanligtvis antingen i renbestånd eller i blandbestånd med fleråriga baljväxter och gräsarter vilka nyttjas till slåtter eller bete. Vid skörd av vall till foder för nötkreatur är den näringsmässiga sammansättningen av stor vikt. Ett högre näringsvärde kan uppnås genom en tidigarelagd skörd, ett ökat antal skördetillfällen samt en väl anpassad gödslingsstrategi. Under senare år har försök genomförts för att undersöka om en anpassning av stubbhöjden och fraktionering av grödan kan vara ett alternativ för att uppnå önskad näringssammansättning vid skörd med lovande resultat. Det är dessa undersökningar (Eriksson 2020) som har gett oss frågeställningen om en anpassning i stubbhöjd har någon påverkan på mängden mekaniska förluster. De mekaniska förluster som uppstår beror på grödans behandling med olika typer av maskiner vid slåtter, vändning, strängläggning och lastning. Syftet med studien var att studera stubbhöjdens påverkan på det mekaniska spillet vid skörd av vall samt att undersöka möjligheterna för att variera stubbhöjden på de maskiner som finns på marknaden. I litteraturstudien presenteras en genomgång om vallodling och dess förluster, stubbhöjdens betydelse, skördeteknik vid vallskörd samt vilka inställningsmöjligheter det finns på vallmaskiner. Ett fältförsök har genomförts för att studera skillnaderna i totalskörd och mängden mekaniskt spill vid fyra olika stubbhöjder. Fältförsöket genomfördes den 31 maj till den 1 juni 2022 i Hulterstad på Öland på en äldre vall (år 5). Försöket var ett helt randomiserat blockförsök med fyra block och fyra led i varje block, de stubbhöjder som mättes var 7, 12, 17 samt 22 cm. Slutsatsen av denna studie är: Vid högre stubbhöjd minskade totalskörden från 5 700 kg torrsubstans per hektar vid 7 cm stubbhöjd till 3 400 kg torrsubstans per hektar vid 22 cm stubbhöjd. Mekaniskt spill vid låg stubbhöjd (7 cm) visade sig vara högst med 107 kg ts per hektar. För stubbhöjderna 12, 17 och 22 cm var spillet mellan 60 och 70 kg ts per hektar. Enligt Tukey´s metod är det en statistisk säkerställd skillnad mellan 7 cm och övriga stubbhöjder. Burna slåttermaskiner kan hantera stubbhöjder från 5 till 12 cm. Vid högre stubbhöjder krävs det att maskinen utrustas med justerbara släpskor. Med bogserade slåttermaskiner kan en högre stubbhöjd uppnås med hjälp av lyftkolvarna.Grassland for fodder production is usually grown either with one species or in a mixture with perennial legumes and grass species, the crop is used for mowing or grazing. When harvesting forage for cattle the nutritional content of energy and protein is important. A higher nutritional value can be achieved through an earlier harvest, an increased number of harvest occasions and a well-adapted fertilization strategy. In recent years, trials have been carried out to investigate whether an adaptation of the stubble height and fractionation of the crop can be an alternative to achieve the desired nutrient composition at harvest with promising results. It is these studies (Eriksson 2020) that have given us the question of whether an adaptation in stubble height has any effect on the amount of mechanical losses. The mechanical losses that occur are due to the treatment of the crop with different types of machines during mowing, tedding, swathing and loading. The purpose of the study was to study the impact of the stubble height on the mechanical losses when harvesting ley and to investigate the possibilities for varying the stubble height on the machines available on the market. The literature study is an overview about ley cultivation and its losses, the importance of stubble height, harvesting techniques for ley harvesting and the adjusting posibilities available on machines for ley production. A field trial has been carried out to study the differences in total yield and the amount of mechanical spillage at four different stubble heights. The field trial was implemented from 31 May to 1 June 2022 in Hulterstad at Öland on an older leyland (year 5). The experiment was a randomized complete block, split-plot design experiment with four blocks and four plots in each block, the stubble heights that were measured were 7, 12, 17 and 22 cm. The conclusion of this study is: At a higher stubble height the total yield decreased from 5 700 kg drymatter per hectare at 7 cm stubble height to 3 400 kg drymatter per hectare at 22 cm stubble height. Mechanical losses at low stubble height (7 cm) was found to be the highest with 107 kg drymatter per hectare. For the stubble heights of 12, 17 and 22 cm, the loss was between 60 and 70 kg drymatter per hectare. There is a statistically significant difference between 7 cm and the other stubble heights, according to Tukey's method. Mounted mowers can handle stubble heights from 5 to 12 cm. For higher stubble heights, the machine must be equipped with adjustable skidshoes. With trailed mowers a higher stubble height can be achieved using the lifting pistons