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

Numerical simulation of an air-supported structure in the air flow

Wind load is often the critical load for air-supported structures. For example, high wind demolished an air-supported tennis court roof in Zhulebino district of Moscow on May 29, 2017. Aerodynamic instability (buffeting, flutter, etc.) can produce excessive slack regions and extremely large deflections. That is why the coupled analysis should be carried out to understanding aeroelastic behavior of air-supported structures under wind loads. The technique of the nonlinear numerical analysis of air-supported structures including fluidstructural interaction (FSI) has been described in the present paper. Numerical simulation of the tunnel test of large-scale air-supported model has been carried out as an example of using this technique. Wind tunnel study is described in the papers1, 2. Experimental deformed shape, pressure coefficients and aerodynamic forces were compared with the results of presented numerical simulation. Computations were carried out with using of commercial code ANSYS 15.0. Some difficulties appeared during simulation process are discussed. An applicability of the proposed technique to the considered problem was confirmed by a good agreement of the experimental and numerical results. Both methods showed that surface wind loads can increase due to deformation of a structure. These conclusions emphasize the importance of researches on wind interaction with air-supported structures

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

Designing of phantom head used in optical diagnostics of brain injury

This article shows the results of an experimental research on properties of the materials chosen for designing of a phantom head, which is to be used in testing of a brain hematoma diagnostics device. We have conducted a comparative research of the optical properties of model materials and real head tissue

Study of the first paramagnetic to ferromagnetic transition in as prepared samples of Mn-Fe-P-Si magnetocaloric compounds prepared by different synthesis routes

International audienceMagnetocaloric materials with composition of Mn 1.3 Fe 0.65 P 0.5 Si 0.5 have been prepared by ball milling and solid-state reaction methods and consolidated using powder annealing, and conventional and spark plasma sintering. Magnetic and calorimetric measurements show remarkable differences upon first cooling, and slight differences on second and further coolings between the samples prepared by different synthesis routes. Further measurements using Hall probe imaging in high magnetic field have been also carried out. As-prepared samples have been cooled down just above the critical temperature, and the first phase transition has been induced by application of a magnetic field. Bulk samples show staircase isothermal magnetization curves whereas powders show smoother transition curves