Number Of Model Experiments Research Articles

Object Detection with Deep Neural Networks for Reinforcement Learning in the Task of Autonomous Vehicles Path Planning at the Intersection

Among a number of problems in the behavior planning of an unmanned vehicle the central one is movement in difficult areas. In particular, such areas are intersections at which direct interaction with other road agents takes place. In our work, we offer a new approach to train of the intelligent agent that simulates the behavior of an unmanned vehicle, based on the integration of reinforcement learning and computer vision. Using full visual information about the road intersection obtained from aerial photographs, it is studied automatic detection the relative positions of all road agents with various architectures of deep neural networks (YOLOv3, Faster R-CNN, RetinaNet, Cascade R-CNN, Mask R-CNN, Cascade Mask R-CNN). The possibilities of estimation of the vehicle orientation angle based on a convolutional neural network are also investigated. Obtained additional features are used in the modern effective reinforcement learning methods of Soft Actor Critic and Rainbow, which allows to accelerate the convergence of its learning process. To demonstrate the operation of the developed system, an intersection simulator was developed, at which a number of model experiments were carried out.

Femto-, Picosecond, and Terahertz Optoacoustics

The possibilities offered by the optoacoustic monitoring of the sea shelf are considered, based on the development of reliable laser sources of femto- and picosecond pulse duration and new ways of detecting and processing high-frequency signals. The basis of these new possibilities is a volume source of sound produced as a result of the breakdown of the medium under the action of ultrashort laser pulses. An overview of new worldwide achievements is presented. The results from a number of model experiments on the optoacoustic monitoring of low concentrations of gas impurities, and on the precise monitoring of the sea shelf, are interpreted.

Modelling snow and ice thickness in the coastal Kara Sea, Russian Arctic

AbstractSnow and ice thickness in the coastal Kara Sea, Russian Arctic, were investigated by applying the thermodynamic sea-ice model HIGHTSI. The external forcing was based on two numerical weather prediction (NWP) models: the High Resolution Limited Area Model (HIRLAM) and the European Centre for Medium-Range Weather Forecasts (ECMWF) model. A number of model experiments were carried out applying different snow parameterization schemes. The modelled ice thickness was compared with in situ measurements and the modelled snow thickness was compared with the NASA Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E) snow thickness. The HIRLAM and ECMWF model results agreed with each other on air temperature and wind. The NWP model precipitation forecasts caught up the synoptic-scale snowfall events, but the magnitude was liable to errors. The ice growth was modelled reasonably well applying HIGHTSI either with a simple parameterization for snow thickness or with the HIRLAM or ECMWF model precipitation as input. For the latter, however, an adjustment of snow accumulation in early winter was necessary to avoid excessive accumulation and consequent underestimation of ice thickness. Applying effective snow heat conductivity improved the modelled ice thickness. The HIGHTSI-modelled snow thickness had a seasonal evolution similar to that of the AMSR-E snow thickness. New field data are urgently needed to validate NWP and ice models and remote-sensing products for snow and sea ice in the Kara Sea.

Nanostructure–Biomolecule Interactions: Implications for Tissue Regeneration and Nanomedicine

Great strides are being made worldwide in our ability to synthesize and assemble nanoscale building blocks to create advanced materials with novel properties and functionalities. The novel properties of nanostructures are derived from their confined sizes and their very large surface-to-volume ratios. Nanostructured surfaces have also been shown to elicit more favorable and selective biomolecule and cellular responses than surfaces at coarser length scales. In the case of nanoscale ceramics and osteoblasts, for example, the benefit results from protein (vitronectin) unfolding at the nanostructured surface. These nanoscale attributes are enabling a variety of nanostructures to form the bases for a new field--nanomedicine. A fundamental issue in much of nanomedicine, and especially tissue regeneration, is to understand and to eventually control nanostructure-biomolecule interactions. To elucidate the fundamental bases for changes of protein conformation and function on nanostructured surfaces, and hence select responses including those of stem cells, a number of model experiments have been carried out. The results of these studies are presented and discussed in the context of the fundamental driving forces for protein conformation changes associated with nanostructures, their relationship to modified cell responses and tissue engineering, and our present knowledge regarding nanostructure properties.

A modified form of diffraction tomography to image boundary structures

Wavefield extrapolation downward from the surface, as applied in migration and associated inversion methods, is a common procedure to image subsurface reflectors. These methods require adequate (i.e., extensive and unaliased) sampling of the surface wavefield. Seismic tomography on the other hand, relates parameters of the upward propagated wavefield to the diffracting image, and sampling requirements are less severe; it is usually the only option to image deep structures from sparse data. The ordinary form of ray tomography, however, imposes a severe smoothness constraint on the boundary; in particular the “tops” and “valleys” of a relatively rough structure are not well‐resolved. We have implemented a generalized form of tomography, which uses both the ray term and the diffraction term linearized in the boundary perturbation. We introduce a generalized reflection coefficient that can be linearized in terms of the (unknown) boundary gradient, and we demonstrate the adequacy of this approximation with the help of synthetic seismograms. We compare the performance of the new inversion method with migration and ray tomography in a number of model experiments where a source and receiver array are used to image (1) a rough sea bottom and (2) a rough sedimentary layer boundary. In these experiments the new method is superior, especially in the outer part of the inversion region where migration and seismic tomography suffer seriously because of the lack of adequate surface information. Even for well‐controlled surveys there is the potential to successfully image a much larger area of the reflector than is possible with migration. Our experiments involved a single reflector in a known velocity‐density structure. The method’s applicability or modifications required when relaxing these assumptions, remains to be investigated.

Growth and activity of Shewanella putrefaciens isolated from spoiling fish

A total of 101 cultures of H 2S-producing organisms isolated from spoiling cod was studied. All cultures were identified as Shewanella putrefaciens. Two groups were distinguished on the basis of pattern of trimethylamine oxide reduction determined by conductance measurement, generation time at 25°C and salt tolerance. The S. putrefaciens cultures were further characterized in a number of model experiments in order to examine the spoilage activity under various conditions. A good correlation between bacterial counts, detection time in conductance measurements and production of trimethylamine and off-odour was found. There were no differences in spoilage potential between strains of S. putrefaciens, and neither initial level of inoculum nor batch of cod used as substrate influenced the levels of bacterial count corresponding to a certain production of trimethylamine and off-odour.

Metabolic behaviors of the core histones in proliferating Friend cells

This study examines the turnover of the core histones in proliferating Friend cells. It was calculated that these proteins turn over with half-lives of 21.6 days for H2A, 13.8 days for H2B, 43.3 days for H3, and 138.6 days for H4. The significant differences in the half-lives of the four core histones indicate that the protein moiety of the nucleosome is not replaced as one entire unit but as a “mosaic” in which each component follows its own rate of replacement. In some experiments the turnover rates of the variants of H2A, H2B, and H3 were compared. The results did not indicate any differences among these histone variants, suggesting that they are not excluded from the mechanisms controlling histone turnover. Metabolic heterogeneity was discovered, however, when the turnover rates of the acetylated and nonacetylated molecules of histone H4 were followed: it appeared that the acetylated molecules are replaced 2.5 times faster. The comparison of the rate of replacement of the histones in proliferating and differentiated cells from one site and their level of acetylation from another suggests that this postsynthetic modification might be involved in the control of histone metabolism. Such a conclusion is supported also by a number of model experiments.

Method for Simultaneous Measurement of Radioactive and Inactive CO 2 Evolved from Soil Samples During Incubation with Labeled Substrates

An apparatus is described which allows the simultaneous, continuous, and highly sensitive analysis of inactive and radioactive CO 2 evolved from 14 C-supplemented soils or other materials. The apparatus consists of a control unit, a commercially available conductometric CO 2 analyzer, and fraction collector. A number of model experiments were conducted to demonstrate the potentials of the apparatus. These included analysis of the time course of priming action, when 14 C-glucose was added to soil, separation of CO 2 respiration peaks caused by simultaneous degradation of radioactive and inactive soil supplements, and study of the effects of a fungicide, Benomyl, on degradation of 14 C-labeled glucose. In the last experiment, partial degradation of the fungicide could also be followed.

Method for Simultaneous Measurement of Radioactive and Inactive CO2 Evolved from Soil Samples During Incubation with Labeled Substrates

An apparatus is described which allows the simultaneous, continuous, and highly sensitive analysis of inactive and radioactive CO(2) evolved from C-supplemented soils or other materials. The apparatus consists of a control unit, a commercially available conductometric CO(2) analyzer, and fraction collector. A number of model experiments were conducted to demonstrate the potentials of the apparatus. These included analysis of the time course of priming action, when C-glucose was added to soil, separation of CO(2) respiration peaks caused by simultaneous degradation of radioactive and inactive soil supplements, and study of the effects of a fungicide, Benomyl, on degradation of C-labeled glucose. In the last experiment, partial degradation of the fungicide could also be followed.