This article puts a perspective to the health risks of smoke from lithium-ion battery (LIB) fires by retrospect simulations of the large-scale event in a warehouse in Morris, IL, USA where about 60 metric tonnes of LIB set on fire on of June 29, 2021. Possible scenarios are sketched where ground concentration maps of PM 2.5 reveal large areas of tens of square kilometres exceeding the action levels set up by the authorities for the event. Besides high concentration in the close vicinity, the plume touchdown is found to be located 5–10 km away from the source. In contrast, irritant gases including HF did not exceed the action levels. The reconstruction of the event was conducted using details from interviews with the owner and first-responders on site, which subsequently was used as input data to a Lagrangian atmospheric transport model. Plume rise due to buoyant flux in a Lagrangian dispersion model was accomplished by adding a vertical speed component derived from discretization of the well-known Briggs formulation. Emission factors were collected from the published scientific literature and implemented in combination with warehouse inventory and visual observations. The importance of this work becomes apparent in view of the rapid increase of LIB’s in, e.g., transportation and energy storage with accompanied fire accidents. These findings support precautions in infrastructure handling LIBs and particularly in large amounts.

A new method for constructing absolutely continuous two-dimensional copulas by differential equations is presented. The copulas are symmetric with respect to reflection in the opposite diagonal. The support of the copula density may be prescribed to arbitrary opposite symmetric hypographs of invertible functions, containing the diagonal. The method is applied to toxicological probit modeling, where new compatibility conditions for the probit parameters are derived.

In this study, calculation of decision threshold and detection limit expressed in counts for low-level radioactivity measurements were evaluated and compared to a Monte Carlo method for the case of paired Poisson-distributed observations, i.e. for discrete variables. The calculated characteristic limits obtained from Monte Carlo calculations were compared with analytical expressions given in literature. The results in this study show that the equations given by Currie are in good agreement with the results from the Monte Carlo calculations simulating nuclear counting applications with a low number of observed counts. An exception is observed for a background corresponding to zero counts. This study also shows that at a low number of counts, the specific boundary conditions of the interval that represents counts corresponding to the presence of the analyte (>or ≥), have an impact on the false positives and negatives rates as defined by the parameters α and β.

Calculation of the decision threshold and detection limit of a measurement, or measurement method, are crucial in order to decide if an analyte is present or not and with what confidence it can be quantified. That decision is important in view of possible actions if something would be detected. In this work, a method for calculating these limits using a Monte Carlo method is presented. In the Monte Carlo method any a priori distribution (e.g. normal distribution, rectangular distribution, triangular distribution) of an input quantity can be selected. Differences between the Monte Carlo calculated characteristic limits and the ones calculated according to ISO 11929:2010 is presented. Moreover, suggestions how to calculate the detection limit when it can not be calculated according to the ISO 11929:2010 are given.

The potential of b-value variations as a medium-term (months, years) precursor was investigated by focusing on the eight largest earthquakes, M-w >= 7.0, occurring between January 2000 and April 2010 in the shallow subduction zones of Cocos and Nazca plates. The available ISC and NEIC lists of events are complete for threshold magnitudes 4.3 (4569 events) and 4.6 (2742 events), respectively. Spatial and temporal perturbations of b were investigated in six regions surrounding the eight largest shocks. A technique of moving spatial- and temporal-windows was applied. Deduced b-values reveal large variations between 0.6 and 2.2. All eight earthquakes took place within regions of low b and were all preceded by significant drops in b-values. Observed correspondence between low b and the occurrence of large earthquakes suggests that b(t) has a potential to be employed in medium-term earthquake predictions in subduction zones of Central and South America. (C) 2018 Elsevier Ltd. All rights reserved.

Atmospheric dispersion modelling is always encumbered by errors and uncertainties originating from different aspects of the weather description as well as the source and dispersion models. Even so, the typical results from these kinds of studies are limited to one realization with no measure of uncertainties in either the temporal or spatial dimensions. This result is then to be interpreted as the most probable outcome given the current information. However, in many situations this limited result and the presentation thereof are far from satisfying and in the worst case even dangerously misleading. To address this shortcoming, this work presents a well‐established method for uncertainty investigation in simulations called Latin hypercube sampling in combination with a weather ensemble which results in an alternative way of estimating the resulting risk area as a function of weather forecast time from a statistical perspective. The main idea with this approach is to use the entire probability distribution of the simulation parameters instead of only one value as is the case in traditional methodology. This is a useful concept that provides additional and valuable information for decision makers.

Funding information Swedish Ministry of Defence Atmospheric dispersion modelling is always encumbered by errors and uncertainties originating from different aspects of the weather description as well as the source and dispersion models. Even so, the typical results from these kinds of studies are limited to one realization with no measure of uncertainties in either the temporal or spatial dimensions. This result is then to be interpreted as the most probable outcome given the current information. However, in many situations this limited result and the presentation thereof are far from satisfying and in the worst case even dangerously misleading. To address this shortcoming, this work presents a well-established method for uncertainty investigation in simulations called Latin hypercube sampling in combination with a weather ensemble which results in an alternative way of estimating the resulting risk area as a function of weather forecast time from a statistical perspective. The main idea with this approach is to use the entire probability distribution of the simulation parameters instead of only one value as is the case in traditional methodology. This is a useful concept that provides additional and valuable information for decision makers.

In situ gamma-ray spectrometry has since the introduction of portable germanium detectors been a widely used method for the assessment of radionuclide ground deposition activity levels. It is, however, a method that is most often associated with fairly large and, more important, poorly known combined measurement uncertainties. In this work an uncertainty analysis of in situ gamma ray spectrometry in accordance with the Guide to the Expression of Uncertainty in Measurements is presented. The uncertainty analysis takes into account uncertainty contributions from the calibration of the detector system, the assumed activity distribution in soil, soil density, detector height and air density. As a result, measurement results from in situ gamma spectrometry will serve as a better basis for decision-making in e.g. radiological emergencies.

Vid byggnation av broar, havsbaserad vindkraft och andra havsbaserade eller strandnara konstruktioner anvands det oftast nagon form av palningsteknik for att fa ner konstruktionen i botten. Detta i ...

The main objective of the MODITIC project is to enhance our fundamental understanding of modelling the dispersion of non-neutral gasses in built-up environments. The project goal is to lay the ground for future improvements of dispersion models used in emergency situations by military personnel as well as civilian emergency services, thereby improving emergency preparedness and response. Atmospheric wind tunnel experiments have been systematically applied and novel experimental data sets for a number of carefully chosen dispersion scenarios have been provided. The same set of configurations has also been subject to computational modelling efforts using both advanced Computational Fluid Dynamics (CFD) and simpler Gaussian models. Experimental data for the release of toxic chemicals from pressurized vessels in order to provide realistic source characterisations in the case of an event have also been made available to the project. Accompanying computations using the conditions of the release experiments has been conducted in order to validate computational models. The project has generated a large database comprising experimental and numerical results for release and dispersion of neutral and dense gasses in configurations ranging from simple to complex geometries. This database will be a valuable addition to the body of reference data needed to advance the fundamental understanding of dispersion in urban environments and its modelling. The database may be used for development, improvement and validation of dispersion models for hazardous materials in urban environments.

We show that the lower and upper Frechét-Hoeffding copulas, which are singular, can be regularized to absolutely continuous copulas. The method, which is constructive and explicit, states sufficient conditions for when an absolutely continuous copula can be achieved by averaging. A higher degree of regularisation cannot be achieved with the proposed method.

When a bioaerosol is introduced to the atmosphere, the concentration will decrease when the aerosol is transported and diluted by wind and turbulence. Other processes, like deposition and biological decay will also act to diminish the concentration. Many important aspects of this take place in the turbulent atmospheric boundary layer i.e. basically within the lowest km the atmosphere. After a brief review of the subdivision of the atmospheric into different layers, we demonstrate by using results from a relatively simple dispersion model for the boundary layer, how different processes affect the resulting concentration. Finally we discuss the implications of sparse and highly fluctuating observed data on the meteorological modeling process. We discuss phenomenological and behavioral models, and we classify errors into model error, input data error and numerical error. We discuss the payoff between the explanatory power and the difficulties of estimating parameters for a detailed model.

Fifteen largest earthquakes, M-w >= 7, occurring between 2000 and 2010 in the Andaman-Sumatra region are studied. The available USGS list of events used is complete for a threshold magnitude M-c = 4.5 and contains 6973 shocks. Spatial and temporal variation of b-values, in the Gutenberg-Richter formula log N = a - bM, was investigated in six selected epicentral regions. The technique of moving spatial- and time-windows was applied. Deduced b-values show large variations from 0.55 to 2.40. The 15 largest events all took place within regions of low b and were preceded by significant drops in b-values. Observed correspondence between low b and the occurrence of large earthquakes suggests that b(t) has a potential which could be employed in a medium term (months, years) earthquake prediction. (C) 2012 Elsevier Ltd. All rights reserved.

In this note we consider radially symmetric plurisubharmonic functions and the complex Monge-Ampere operator. We prove among other things a complete characterization of unitary invariant measures for which there exists a solution of the complex Monge-Ampere equation in the set of radially symmetric plurisubharmonic functions. Furthermore, we prove in contrast to the general case that the complex Monge-Ampere operator is continuous on the set of radially symmetric plurisubharmonic functions. Finally we characterize radially symmetric plurisubharmonic functions among the subharmonic ones using merely the laplacian.

We study the possibility of improved tracking of underwater targets based on sensor data from a network of underwater sensors. The improvement by fusion implicitly assumes that the tracking can be assessed in a reliable and objective way. How tracking performance can be assessed is the main issue in this paper. We introduce two categories of performance metrics. The first set, the On-line metrics, have been defined to be independent of a priori knowledge of the target positions. The On-line metrics are intended to be usable in real-time. The second set, the Off-line metrics, is based on comparisons between the estimated tracks and the a, priori known positions (e.g. GPS-positions) of the target. The Off-line metrics are intended for evaluation purposes of the On-line metrics only. The key question is whether the On-line metrics correlate well with the Off-line metrics. In this paper we use experimental data from underwater sensors to assess the tracking performance of underwater targets. Data from acoustic and electric sensor arrays are used either standalone or fused using a Kalman filter. The evaluation is done based on sea-trial data from both sensor-types. The results from applying the On-line and Off-line metrics are discussed. We demonstrate a high correlation between the On-line and Offline metrics estimated from real data. Our conclusion is that the suggested On-line metrics are possible to use as tools for evaluation of tracking performance in real time.

Two aftershock series following the December 26, 2004 (M-w = 9.0) and the March 28, 2005 (M-w = 8.6) earthquakes off coast of NW Sumatra are studied. Deduced space heterogeneity of b-values, in the Gutenberg-Richter formula, and p-values, in the Omori law, show significant variations. General agreement is found between areas of high b and areas of significant slip predicted by different source models presented by other workers. Correlation with high p-values does exist, however, is less pronounced. The largest aftershocks occur during or near time periods when b-values reach their local minima. To examine the stability of results, two global earthquake catalogues (ISC and NEIC), different threshold magnitudes, moving-window lengths and moving steps were employed. The presented b- and p-distributions exhibit high confidence levels. (C) 2012 Elsevier Ltd. All rights reserved.

Underwater surveillance against small and low signature targets is challenging, especially in disturbed and shallow water areas such as harbors. Today the most frequently used system for surveillance in harbors is active sonar. However, the detection range of an active system can rapidly degrade due to changes in the sound propagation conditions and in the ambient noise. We focus our research on how passive underwater sensors can be used as a complement to active acoustic systems. We have previously reported on diver detectors for passive acoustic and electric field data, with promising results. The use of the two sensor systems together is mainly motivated by the fact that the acoustic and electric background noise often are uncorrelated. In this paper we test different data fusion methods in order to combine the decisions from the two detectors into one unified decision. The performance of the detectors and the data fusion methods is evaluated using data from a sea trial conducted in the port of Gothenburg in 2009. We present an approach to fusion that will result in a robust system solution for harbor security.

We report on the photoinduced decomposition of acetone on Zr- and Nb-doped anatase TiO2 nanoparticles prepared by the sol-gel method in oxygen-free environment (N-2) and synthetic air, respectively. Physical properties of the nanoparticles were determined by TEM, SEM, AFM, XRD, and UV-vis spectroscopy. Photoinduced surface reactions were monitored by in situ Fourier transform infrared (FTIR) spectroscopy. Acetone photo-oxidation occurs in the absence Of O-2 in the reaction gas and is proposed to be due to reactions with photoactivated surface oxygen. In N-2 atmosphere a new parallel reaction pathway is found that stimulates surface carbonate formation. A coupled diffusion-reaction model was developed to quantitatively determine the role of O diffusion. The results yield quantitative support to an oxygen surface diffusion mechanism, which depletes the surface from oxygen and gradually deactivates the particles in the absence of external oxygen supply. The diffusion reaction pathway is significant on the doped TiO2 particles. The contribution of this reaction pathway amounts to up to 65% of the total PID rate on Nb- and Zr-doped TiO2 in synthetic air environment, while it gives only a minor contribution on pure TiO2,