SOFTWARE DEVELOPMENT FOR RENDERING THREE-DIMENSIONAL SURFACES IN A WEB BROWSER

Представлена реализация программного обеспечения для построения трехмерных поверхностей с использованием трассировки лучей, выполняемого в веб-браузере персонального компьютера или смартфона. Подход веб-приложений стал широко применим в последние годы из-за развития сети Интернет. Современные веб-браузеры имеют достаточную вычислительную мощность для реализации сложных веб-приложений, а не ограничиваются только веб-сайтами. В процессе разработки были изучены различные методы построения поверхностей и методы визуализации, чтобы подобрать наиболее оптимальные для реализации веб-приложения. Были проанализированы и представлены базовые способы создания трехмерных поверхностей. Выделены ключевые различия каркасного и полигонального способа задания поверхности. Рассмотрен ряд моделей с процедурно вычисляемыми поверхностями. Подробно описан кинематический способ образования поверхностей, а также описан разработанный алгоритм для преобразования кинематических моделей в поверхность с использованием полигональной сетки. Подробно описан процесс визуализации и метод трассировки лучей. Продемонстрирован способ работы с видеочипом и распараллеливанию вычислений для оптимизации веб-приложения с помощью библиотеки GPU.js. Представлена структура веб-приложения с описанием главных каталогов проекта. Структура проекта основана на фреймворке Vue.js, благодаря чему функционал веб-приложения позволяет безгранично расширять. Для демонстрации работы веб-приложения представлен пример пошагового задания кинематической поверхности и визуализации на сцене с применением графических эффектов, таких как закраска и освещение, а также представлен пример с визуализацией множества объектов на сцене The article presents the implementation of software for rendering 3D-surfaces using ray tracing, running in a web browser of computers or smartphones. The web application approach has become widespread in recent years due to the development of the Internet. Modern web browsers have enough processing power to run complex web applications and are not limited to just websites. During the development process, various methods for constructing surfaces and visualization methods were analyzed to choose the most optimal solution for web applications. We analyzed and presented basic methods of creating 3D surfaces. We highlighted the key differences between wireframe and polygonal methods of surface definition. We considered several models with dynamic surface computation. We described the kinematic method of surface formation in detail and the developed algorithm for transforming kinematic models into a surface using a polygonal mesh. We described in detail the rendering process and ray tracing method. We demonstrated a way of working with a video chip and parallelizing computations to optimize a web application using the GPU.js library. We presented the structure of a web application with a description of the main project directories. The project structure is based on the Vue.js framework. The framework allows one to endlessly expand the functionality of a web application. The article presents how the web application works and example of step-by-step creation of a kinematic surface and rendering on a scene using graphic effects such as shading and lighting. Also it contains an example of rendering many objects on a scene

Monitoring Catalytic 2-Propanol Oxidation over Co3O4 Nanowires via In Situ Photoluminescence Spectroscopy

Spectroscopic methods enabling real-time monitoring of dynamic surface processes are a prerequisite for identifying how a catalyst triggers a chemical reaction. We present an in situ photoluminescence spectroscopy approach for probing the thermo-catalytic 2-propanol oxidation over mesostructured Co3O4 nanowires. Under oxidative conditions, a distinct blue emission at ~420 nm is detected that increases with temperature up to 280 °C, with an intermediate maximum at 150 °C. Catalytic data gained under comparable conditions show that this course of photoluminescence intensity precisely follows the conversion of 2-propanol and the production of acetone. The blue emission is assigned to the radiative recombination of unbound acetone molecules, the n - π* transition of which is selectively excited by a wavelength of 270 nm. These findings open a pathway for studying thermo-catalytic processes via in situ photoluminescence spectroscopy thereby gaining information about the performance of the catalyst and the formation of intermediate products.

Composite Observer-Based Adaptive Dynamic Surface Control for Fractional-Order Nonlinear Systems with Input Saturation

This article proposes an adaptive neural output feedback control scheme in combination with state and disturbance observers for uncertain fractional-order nonlinear systems containing unknown external disturbance, input saturation and immeasurable state. The radial basis function neural network (RBFNN) approximation is used to estimate unknown nonlinear function, and a state observer as well as a fractional-order disturbance observer is developed simultaneously by using the approximation output of the RBFNN to estimate immeasurable states and unknown compounded disturbances, respectively. Then, a fractional-order auxiliary system is constructed to compensate the effects caused by the saturated input. In addition, by introducing a dynamic surface control strategy, the tedious analytic computation of time derivatives of virtual control laws in the conventional backstepping method is avoided. The proposed method guarantees that the boundness of all signals in the closed loop system and the tracking errors converge to a small neighbourhood around the origin. Finally, two examples are provided to verify the effectiveness of the proposed control method.

Finite-time fuzzy dynamic surface control for permanent magnet synchronous motor stochastic systems with input constraint and load disturbance

In this paper, a finite-time adaptive fuzzy dynamic surface control (DSC) method is proposed for the position tracking control of permanent magnet synchronous motors (PMSMs) stochastic nonlinear system with input constraint and load disturbance. First, the stochastic disturbance of PMSMs is considered in operation, and the fuzzy control method is applied to cope with the stochastic nonlinear function in the motor model. Second, the DSC technique is applied to avoid the “explosion of complexity” in the backstepping design. Moreover, the finite-time control is applied to the stochastic nonlinear system of PMSMs to improve the convergence speed of the system, tracking accuracy, and anti-interference ability. Conclusive, simulation results are given to verify the method that can achieve fast tracking of the desired signal.

Robust Adaptive Neural Cooperative Control for the USV-UAV Based on the LVS-LVA Guidance Principle

Around the cooperative path-following control for the underactuated surface vessel (USV) and the unmanned aerial vehicle (UAV), a logic virtual ship-logic virtual aircraft (LVS-LVA) guidance principle is developed to generate the reference heading signals for the USV-UAV system by using the “virtual ship” and the “virtual aircraft”, which is critical to establish an effective correlation between the USV and the UAV. Taking the steerable variables (the main engine speed and the rudder angle of the USV, and the rotor angular velocities of the UAV) as the control input, a robust adaptive neural cooperative control algorithm was designed by employing the dynamic surface control (DSC), radial basic function neural networks (RBF-NNs) and the event-triggered technique. In the proposed algorithm, the reference roll angle and pitch angle for the UAV can be calculated from the position control loop by virtue of the nonlinear decouple technique. In addition, the system uncertainties were approximated through the RBF-NNs and the transmission burden from the controller to the actuators was reduced for merits of the event-triggered technique. Thus, the derived control law is superior in terms of the concise form, low transmission burden and robustness. Furthermore, the tracking errors of the USV-UAV cooperative control system can converge to a small compact set through adjusting the designed control parameters appropriately, and it can be also guaranteed that all the signals are the semi-global uniformly ultimately bounded (SGUUB). Finally, the effectiveness of the proposed algorithm has been verified via numerical simulations in the presence of the time-varying disturbances.

Increasing wear and corrosion resistance of steel products by combined laser thermomechanical treatment

A technique is presented for hardening metal products, in particular, the main tools (hammers) and cases of core drilling bits made of steel 30HGSA, using thermomechanical surface treatment according to a separate scheme. The method of combined laser thermomechanical hardening used in the study consists in the use of shot peening followed by laser heat treatment. Its use makes it possible to increase the operational properties of steel products, in particular, their wear and corrosion resistance. Based on the results of theoretical and experimental studies, the paper substantiates the features of dynamic surface plastic deformation for the analysis of impact during shot peening. The advantages of using laser hardening without surface melting are presented. Experimental research methods are proposed for determining the structural-phase composition, structure of the surface layer, hardness and microhardness of the hardened zones of steel 30HGSA. The range of rational modes of impact shot peening and thermal laser treatment has been determined. A device for testing samples for wear resistance has been developed. Methods of testing for wear and corrosion resistance of the surface of samples are proposed for assessing the tribological properties and contact interaction of materials under quasi-static and dynamic loading conditions. It is concluded that rational technological modes of hardening tools made of steel 30HGSA using combined laser thermomechanical treatment allow increasing the depth of the hardened layer by ~1.5 times compared to laser heat treatment. In addition, they provide the microhardness of the surface layer of ~5400 MPa, which is ~2.5 times higher than the microhardness of the base material

Tensiometry as a Simple Analytical Method for Quantification of Solubility and Release of Aroma Molecules in Aqueous Media

Dynamic tensiometry is shown to be a high-potential analytical tool in assessing physico-chemical characteristics of fragrance molecules, such as solubility limit, volatility as well as much rarely assessed interfacial activity of these amphiphilic molecules. Surface tension of aqueous solutions of selected essential oils has been measured as a function of time and fragrance concentration using maximum bubble pressure method. The effect of the temperature and saline solution on the rate of dissolution in water was assessed. Dynamic surface tension turned to be sensitive to the composition of fragrances, as demonstrated on examples of natural and synthetic mixtures. Furthermore, presented work reveals the possibility of maximum bubble pressure tensiometry method to quantify the amount of fragrance compositions in flavored salts, including the artificially aged carrier samples. Suggested here analytical approach can be used for the detection of the purity of essential oils, for the optimization of compositions and of the manufacturing processes of fragrances-containing products, as well as for the assessment of the release/evaporation of fragrances from carrier systems.