FPGA Implementation of Convolutional Neural Networks with Fixed-Point Calculations

Neural network-based methods for image processing are becoming widely used in practical applications. Modern neural networks are computationally expensive and require specialized hardware, such as graphics processing units. Since such hardware is not always available in real life applications, there is a compelling need for the design of neural networks for mobile devices. Mobile neural networks typically have reduced number of parameters and require a relatively small number of arithmetic operations. However, they usually still are executed at the software level and use floating-point calculations. The use of mobile networks without further optimization may not provide sufficient performance when high processing speed is required, for example, in real-time video processing (30 frames per second). In this study, we suggest optimizations to speed up computations in order to efficiently use already trained neural networks on a mobile device. Specifically, we propose an approach for speeding up neural networks by moving computation from software to hardware and by using fixed-point calculations instead of floating-point. We propose a number of methods for neural network architecture design to improve the performance with fixed-point calculations. We also show an example of how existing datasets can be modified and adapted for the recognition task in hand. Finally, we present the design and the implementation of a floating-point gate array-based device to solve the practical problem of real-time handwritten digit classification from mobile camera video feed

Mechanical properties of technical coated fabrics under axial and off-axial tensile tests

In the paper, laboratory tests carried out by the authors with axial (0° - warp, 90° - weft) and off-axial (15°, 30°, 45°, 60°, 75°) tensile and also with biaxial tensile with shear with different load ratios are described. The purpose of the research was to determine the mechanical properties of material used at numerical simulations of membrane structures. Two different types of a technical coated fabrics used in the experiments - with and without Precontraint® technology. To measure the displacement and strain fields on the surface of specimens, the method of digital image correlation has been used. Numerical simulation of technical coated fabrics, imitating carried-out laboratory tests, has been executed with using of software program Ansys Workbench. It is revealed owing to analysis of results of numerical simulations that shear stresses make a significant contribution to the stress-strain state of material in off-axial and biaxial tensile with shear. The possibility of applying several classical criteria for fracture strength of composite materials in order to predict and evaluate the behavior of technical coated fabrics under load is shown

КОНВЕКЦИЯ ВОЗДУХА В СНЕЖНОМ ПОКРОВЕ МОРСКОГО ЛЬДА (AIR CONVECTION IN SNOW COVER OF SEA ICE)

For the first time, data on stability of stationary convective filtration within infinite horizontal layer of snow covering the flat surface of floating ice is presented in this article. An analytical solution of the linearized problem was obtained with the use of the Galerkin method, and the parametric analysis of the problem was performed. It was found that the stability criteria (Rayleigh filtration numbers) obtained with consideration for the heat exchange of snow cover with the atmosphere did not exceed the known value of 4π2 for a horizontal porous layer with impermeable isothermal boundaries. As expected, the interaction with the atmosphere has the most significant impact on the critical Rayleigh numbers, while influence of variations in snow density and ice thickness and the thickness of the underlying layer of ice are small. Based on data of ice and meteorological observations made in the winter of 2015/16 in the Western part of the Laptev Sea together with calculations of the fast ice evolution, the values and temporal variability of temperature gradients and the Rayleigh numbers in the snow cover were obtained using a thermodynamic model. It was found that both, the model and observed magnitudes, exceeded their critical values determined by solving the stability problem. The conclusion is made that the convective regime of the heat transfer does really exist in the snow cover, and thus its contribution to the thermal and mass balance of sea ice during winter period should be taken into account

Карстоопасность территории архитектурно-этнографического музея «Хохловка»

Exogenous geologic processes (EGP) on the territory of Perm Krai have a wide development. In this list, karst occupies a special position, as this process is widespread and, in addition, can serve as a catalyst for associated hazardous geological processes. At the request of the management of the State Regional Budgetary Cultural Institution "Perm Regional Museum of History" the authors conducted a reconnaissance survey of karst occurrences in the territory of the architectural and ethnographic museum "Khokhlovka" to assess the geological risks and to ensure the safe operation of cultural heritage object, non-capital structures and engineering facilities. This article presents the results of preliminary assessment of karst hazard of the territory, based on the analysis of stock materials, remote sensing data and field reconnaissance survey.Экзогенные геологические процессы (ЭГП) на территории Пермского края имеют широкое развитие. В этом перечне карст занимает особое положение, так как этот процесс имеет широкое распространение и, кроме того, может служить катализатором сопутствующих опасных геологических процессов. По просьбе руководства Государственного краевого бюджетного учреждения культуры «Пермский краеведческий музей» авторами проведено рекогносцировочное обследование карстопроявлений территории архитектурно-этнографического музея «Хохловка» для оценки геологических рисков и обеспечения безопасной эксплуатации объектов культурного наследия, некапитальных сооружений и инженерных объектов. В данной статье приводятся результаты предварительной оценки карстоопасности территории, выполненные на основе анализа фондовых материалов, данных дистанционного зондирования Земли и полевого рекогносцировочного обследования

Growth of the fast ice and its influence on the freezing of bottom sediments in the Buor-Khaya Bay coastal zone, Laptev Sea (in Russian)

Results of the ice and hydrological measurements carried out in the winter of 2014/15 in theTiksiGulf(Buor-KhayaBay) are described. These data served a basis for development of a conceptual thermodynamic model of seasonal freezing of the sea water layers and underlying bottom sediments in the sea-shore zone. The model uses two methods of localization of the phase transition zones: a classical (frontal) one is used for water, while another one within the range of temperatures – for the bottom. For real atmospheric conditions, we investigated specific features of the water freezing through in the shallow coastal zone of theLaptev Sea. The quantitative characteristics of the process were obtained. The calculations demonstrated that the distinguishing feature of the process is a stabilization of the ice thickness, taking place due to essential increasing of a salinity of the sea water. As a result of this, a shallow water body does not frozen through down to the bottom at even the very low air temperatures. Cooled salt waters does not allow liquid to be frozen in pores of the bottom ground. Salinization of the under-ice water layer can cause the melting of fast ice in the shallow water with its simultaneous increase away from the coast. Ice formation in water layers and bottom sediments begins at the same time, although it proceeds differently at different depths. Due to salinization of the bottom ground a continuous frozen zone is not formed, and the whole layer of freezing precipitation is a two-phase (partially frozen) area. As a whole, the model estimates of the process parameters including the motions of the phase fronts agree with known data of direct measurements. Despite such conformity, the model data should be considered as only evaluative ones. If a bottom is flat, the horizontal mixing and advection, which are not reproduced by a one-dimensional model in principle, the actual salinity parameters will most likely not reach the calculated values. However, for small values of the tides in theBuor-KhayaBayand insignificant reverse flows of salt, effect of the last ones does not apparently exert significant influence on the intensity of cooling of the under-ice water layer as well as on the ice formation in upper layers of the bottom within such time scales as a season

Elastic Spin Relaxation Processes in Semiconductor Quantum Dots

Electron spin decoherence caused by elastic spin-phonon processes is investigated comprehensively in a zero-dimensional environment. Specifically, a theoretical treatment is developed for the processes associated with the fluctuations in the phonon potential as well as in the electron procession frequency through the spin-orbit and hyperfine interactions in the semiconductor quantum dots. The analysis identifies the conditions (magnetic field, temperature, etc.) in which the elastic spin-phonon processes can dominate over the inelastic counterparts with the electron spin-flip transitions. Particularly, the calculation results illustrate the potential significance of an elastic decoherence mechanism originating from the intervalley transitions in semiconductor quantum dots with multiple equivalent energy minima (e.g., the X valleys in SiGe). The role of lattice anharmonicity and phonon decay in spin relaxation is also examined along with that of the local effective field fluctuations caused by the stochastic electronic transitions between the orbital states. Numerical estimations are provided for typical GaAs and Si-based quantum dots.Comment: 57 pages, 14 figure