Overview of spatial verification methods and their application to ensemble forecasting

State-of-the-art high-resolution NWP models simulate mesoscale systems with a high degree of detail, with large amplitudes and high gradients of fields of weather variables. Higher resolution leads to the spatial and temporal error growth and to a well-known double penalty problem. To solve this problem, the spatial verification methods have been developed over the last two decades, which ignore moderate errors (especially in the position), but can still evaluate the useful skill of a high-resolution model. The paper refers to the updated classification of spatial verification methods, briefly describes the main methods, and gives an overview of the international projects for intercomparison of the methods. Special attention is given to the application of the spatial approach to ensemble forecasting. Popular software packages are considered. The Russian translation is proposed for the relevant English terms. Keywords: high-resolution models, verification, double penalty, spatial methods, ensemble forecasting, object-based methods

EVALUATION OF THE EFFECTIVENESS OF MAGNETIC SEPARATORS WITH FERROMAGNETIC BALL NOZZLE

Магнитные сепараторы с применением ферромагнитной насадки, имеющими высокие градиенты магнитного поля в рабочем пространстве, находят применение для очистки пылегазовых потоков и суспензий от магнитных примесей и являются достаточно экономичными в промышленных условиях. Исследованы полупромышленные сепараторы периодического и непрерывного действия с щаровой ферромагнитной насадкой для очистки антифрикционной присадки «Деста» от магнитных примесей. Для исключения потерь времени на промывку насадки, обеспечения постоянной производительности по суспензии и качества очистки суспензий авторами разработана конструкция и предложен метод расчета основных параметров сепаратора непрерывного действия. Проведены экспериментальные исследования работы сепараторов периодического и непрерывного действия одинаковых габаритов рабочего пространства и производительностей по очищаемой суспензии, которые показали неоспоримые преимущества сепаратора непрерывного действия. Magnetic separators with the use of a ferromagnetic nozzle, having high gradients of the magnetic field in the working space, are used for cleaning dust and gas flows and suspensions from magnetic impurities and are quite economical in industrial conditions. Semi-industrial separators of periodic and continuous action with ferromagnetic ball nozzle for cleaning the antifriction additive "Desta" from magnetic impurities are studied. To eliminate the loss of time for flushing the ferromagnetic ball nozzle, to ensure constant suspension performance and the quality of cleaning suspensions, the authors have developed a design and proposed a method for calculating the main parameters of a continuous separator. Experimental studies of the operation of separators of periodic and continuous action of the same dimensions of the working space and the performance of the cleaned suspension were carried out, which showed the undeniable advantages of a continuous separator.

A new approach to precise mapping of local temperature fields in submicrometer aqueous volumes

Nanodiamonds hosting temperature-sensing centers constitute a closed thermodynamic system. Such a system prevents direct contact of the temperature sensors with the environment making it an ideal environmental insensitive nanosized thermometer. A new design of a nanodiamond thermometer, based on a 500-nm luminescent nanodiamond embedded into the inner channel of a glass submicron pipette is reported. All-optical detection of temperature, based on spectral changes of the emission of “silicon-vacancy” centers with temperature, is used. We demonstrate the applicability of the thermometric tool to the study of temperature distribution near a local heater, placed in an aqueous medium. The calculated and experimental values of temperatures are shown to coincide within measurement error at gradients up to 20 °C/μm. Until now, temperature measurements on the submicron scale at such high gradients have not been performed. The new thermometric tool opens up unique opportunities to answer the urgent paradigm-shifting questions of cell physiology thermodynamics.

Using diffusion MRI data acquired with ultra-high gradients to improve tractography in routine-quality data

The development of scanners with ultra-high gradients, spearheaded by the Human Connectome Project, has led to dramatic improvements in the spatial, angular, and diffusion resolution that is feasible for in vivo diffusion MRI acquisitions. The improved quality of the data can be exploited to achieve higher accuracy in the inference of both microstructural and macrostructural anatomy. However, such high-quality data can only be acquired on a handful of Connectom MRI scanners worldwide, while remaining prohibitive in clinical settings because of the constraints imposed by hardware and scanning time. In this study, we first update the classical protocols for tractography-based, manual annotation of major white-matter pathways, to adapt them to the much greater volume and variability of the streamlines that can be produced from today's state-of-the-art diffusion MRI data. We then use these protocols to annotate 42 major pathways manually in data from a Connectom scanner. Finally, we show that, when we use these manually annotated pathways as training data for global probabilistic tractography with anatomical neighborhood priors, we can perform highly accurate, automated reconstruction of the same pathways in much lower-quality, more widely available diffusion MRI data. The outcomes of this work include both a new, comprehensive atlas of WM pathways from Connectom data, and an updated version of our tractography toolbox, TRActs Constrained by UnderLying Anatomy (TRACULA), which is trained on data from this atlas. Both the atlas and TRACULA are distributed publicly as part of FreeSurfer. We present the first comprehensive comparison of TRACULA to the more conventional, multi-region-of-interest approach to automated tractography, and the first demonstration of training TRACULA on high-quality, Connectom data to benefit studies that use more modest acquisition protocols.

Free Surface Effect Assessment of the Flow Around the DARPA SUBOFF-5470 Submarine Using OpenFOAM

An important parameter to submarine navigation and control is determining the hull speed relative to the surrounding sea. The object of this paper is to find possible locations for speed sensors on a submarine. The probes should be fitted to the hull areas where the water flow is free of turbulence structures, vortices, or bubble formation to obtain a reliable measurement. In this work, a rational procedure is proposed to identify the probe installation site on the hull of the DARPA SUBOFF-5470 submarine, through numerical simulations using OpenFOAM. Three different depth conditions at three different navigation speeds were considered to assess the free-surface effect. First, verification and validation procedures were completed at deep water conditions (H/D = 5.4). The results of this analysis indicate a convergence ratio of 0.49 with an uncertainty of 0.04%SC. Later, a grid convergence analysis was completed at periscope depth conditions (H/D = 1.1), within the highly nonlinear Froude range. These results show an oscillatory convergence with an uncertainty of 0.78%. Finally, the hull region between 5 and 15% from the bow of the submarine length is recommended for installing the speed probe, considering the linearity of the flow, without high gradients and vortex structures.

A comprehensive temporal patterning gene network in Drosophila medulla neuroblasts revealed by single-cell RNA sequencing

During development, neural stem cells are temporally patterned to sequentially generate a variety of neural types before exiting the cell cycle. Temporal patterning is well-studied in Drosophila, where neural stem cells called neuroblasts sequentially express cascades of Temporal Transcription Factors (TTFs) to control the birth-order dependent neural specification. However, currently known TTFs were mostly identified through candidate approaches and may not be complete. In addition, many fundamental questions remain concerning the TTF cascade initiation, progression, and termination. It is also not known why temporal progression only happens in neuroblasts but not in their differentiated progeny. In this work, we performed single-cell RNA sequencing of Drosophila medulla neuroblasts of all ages to study the temporal patterning process with single-cell resolution. Our scRNA-seq data revealed that sets of genes involved in different biological processes show high to low or low to high gradients as neuroblasts age. We also identified a list of novel TTFs, and experimentally characterized their roles in the temporal progression and neural fate specification. Our study revealed a comprehensive temporal gene network that patterns medulla neuroblasts from start to end. Furthermore, we found that the progression and termination of this temporal cascade also require transcription factors differentially expressed along the differentiation axis (neuroblasts -> -> neurons). Lola proteins function as a speed modulator of temporal progression in neuroblasts; while Nerfin-1, a factor required to suppress de-differentiation in post-mitotic neurons, acts at the final temporal stage together with the last TTF of the cascade, to promote the switch to gliogenesis and the cell cycle exit. Our comprehensive study of the medulla neuroblast temporal cascade illustrated mechanisms that might be conserved in the temporal patterning of neural stem cells.

Validation of an Experimental Procedure to Determine Bedload Transport Rates in Steep Channels with Coarse Sediment

The current study presents an experimental procedure used to determine bedload sediment transport rates in channels with high gradients and coarse sediment. With the aim to validate the procedure for further investigations, laboratory experiments were performed to calculate bedload transport rates. The experiments were performed in a laboratory tilting flume with slopes ranging from 3% to 5%. The sediment particles were uniform in shape (spheres). The experiments were divided into four cases based on sediment size. Three cases of uniform sizes of 10 mm, 15 mm and 25 mm and a case with a grain size distribution formed with the uniform particle sizes were considered. From the experimental results a mathematical bedload transport model was obtained through multiple linear regression. The experimental model was compared with equations presented in the literature obtained for gravel bed rivers. The experimental results agree with some of the models presented in the literature. The closest agreement was seen with models developed for steep slopes especially for the highest slopes considered in the present study. Therefore, it can be concluded that the methodology used can be replicated for the study of bedload transport rates of channels with high gradients and coarse sediment particles to study more general cases of this process such as sediments with non-uniform shapes and sizes. However, a simplified model is proposed to estimate bedload transport rates for slopes up to 5%.

High-Order Hybrid WCNS-CPR Scheme for Shock Capturing of Conservation Laws

By introducing hybrid technique into high-order CPR (correction procedure via reconstruction) scheme, a novel hybrid WCNS-CPR scheme is developed for efficient supersonic simulations. Firstly, a shock detector based on nonlinear weights is used to identify grid cells with high gradients or discontinuities throughout the whole flow field. Then, WCNS (weighted compact nonlinear scheme) is adopted to capture shocks in these areas, while the smooth area is calculated by CPR. A strategy to treat the interfaces of the two schemes is developed, which maintains high-order accuracy. Convergent order of accuracy and shock-capturing ability are tested in several numerical experiments; the results of which show that this hybrid scheme achieves expected high-order accuracy and high resolution, is robust in shock capturing, and has less computational cost compared to the WCNS.

Rescue blankets hamper thermal imaging in search and rescue missions

Thermal imaging for unmanned aerial vehicles is used to search for victims in poor visibility conditions. We used a gimbal-mounted camera for thermo-radiation measurements of body temperature from persons covered with rescue blankets in the hibernal wilderness setting. Long-wave infrared radiation in the spectral range between 7500 and 13,500 nm was evaluated. Parts of this research have previously been published in a review on electromagnetic radiation reflectivity of rescue blankets (https://www.mdpi.com/2079-6412/10/4/375/htm). Surface temperature measurement was diminished by clothing, namely by 72.6% for fleece, by 82.2% for an additional down jacket and by 92.3% for an additional all-weather jacket, as compared to forehead temperature. Furthermore, we detected that a single-layer rescue blanket is sufficient to render recognition of a body shape impossible. With three layers covering a clothed body infrared transmission was almost completely blocked. However, rescue blankets increase visibility for thermal cameras due to high gradients in temperature. Conspicuously low temperatures from objects of 1 to 2 m length may indicate reflections from rescue blanket surfaces in a cold environment. Ideally, rescue blankets should be removed from the body to increase the chance of being located when using thermal imaging to search for victims in search and rescue missions.