Abstract:Nowadays the progress in modern technologies in area of computer science and wide understanding communication, both using computer and communication with the computer, has a direct influence on our real life, institution and individuals. Rapid growth of the Internet and the easy access to it, makes that lots of information is available on the web. On the other hand, the Internet is not only for special groups of people. Nowadays more and more disabled people, also blind people, are using computers and the Internet. The adaptive technology industry is mainly focused on computer access, through screen readers and others specialized devices which give the blind people access to the sighted world. In the article there is presented internet's bank application controlled by means of voice and keyboard, which helps disabled people in a prosaic tasks.
Abstract:Indirect measurement of fretting amplitude, as a difference of displacement between specimens, in many cases is not in accordance with the facts. And this discordance is more, than less amplitude of a tangential displacement. A complex operation of an adhesion, the elasticity of a contact layer and dynamic phenomena of a system “contact – subsurface layer – body as a whole”, do not give point significance of slip amplitude for usual method of a measurement. Our interest for friction has two main principles: the law of friction with low velocities (Stribek effect) and dynamics of a system “contact layer – body as a whole”. Thus, presented two-dimensional model consists of three bodies: one of which makes oscillatory movement, second – elastic element with a mass and third body – movement of all element. The performance of stick-slip regime is represented by ratio between a mass of an elastic layer and all elements, friction laws, stiffness and frequency of oscillations.
Abstract:A post-buckling path for a cylindrical shell under torsional moment is unstable one. It means that the loss of stability of a shell can be associated with a snap-through, which can lead to very large displacements and, finally, to destruction of the structure.The effect of modification of the post-buckling behavior in most cases has been obtained by changing of geometry of a structure. In this paper an alternative concept is applied, namely stabilization of the post-buckling path is obtained by application of an additional loading acting to the structure without changing its geometry. This additional loading is applied to a structure by imposing a certain axial displacement to the ends of the shell. It causes an axial tensional force, which can stabilize the post-buckling path. The problem was formulated as a problem of optimization, namely the minimum value of the axial load - the initial pretension u, which leads, together with the passive force, to stabilization of the post-buckling path is looked for. Calculations were performed using ANSYS code.
Abstract:Cellular Automata is mathematical idealization of a physical system in which space and time are discrete. The design domain is divided into a lattice of cells, states of which are updated synchronously in discrete time steps according to some local rules. The behavior of each cell depends on its present state and states of its neighbors. This paper presents a topology optimization for 2D elastic structures by using the concept of Cellular Automata (CA). The novel local update rule is proposed. The presented concept is illustrated by results of numerical examples.
Abstract:One of the most significant problems nowadays is an issue of vibrations suppression. Vibrations can have negative effects on proper work of industrial systems as well as on operators health. In recent years many researchers have devoted a lot of attention to smart materials, which can be implemented in vibration suppression systems. This paper presents a beam structure with piezoelectric stripes glued to the surface. The model was made in Ansys application utilizing Finite Element Method (FEM). The aim of the analysis was choosing the correct model and quality of the mesh which will ensure that the model can be used for wide spectrum of analysis. It was shown that only 3D model represents the behavior of vibrating beam in all the aspects and gives results very similar to analytical ones. Presented model may be utilized for multimodal passive damping by connecting the correct electric circuit with calculated values of inductance and resistance.
Abstract:In this paper there was proposed the trabecular bone structure analysis using fuzzy logic. Theoretical and algorithmic basis method of measurement structural parameters there was presented. Application using FDT algorithm was adapted to analysis thickness of trabecular bone. Study methodics of measurements of gray level images allows using physical relation between mechanical and structural properties of images especially for limited resolution images, with data inaccuracies, graded object compositions and for structures having similar intensities for different parts.
Abstract:In the paper the principles of calculation of powder hydrocannon are presented. For design of hydrocannon devices for given form of running part on the first step the pressure of the water on inside surface of device is calculated at different time step. The maximum value of pressure during the shot is determined and the approximated value of outer radius is calculated on the basis of the strength of materials theory. In the second stage the deformed mode is defined by ANSYS according to stationary distribution of pressure and radius which was obtained earlier. When the correction of the dimensions are done, and finally, the dynamic calculation of the deflected mode is realized by numerical method with artificial viscosity taking into account elastic and plastic deformation, the dynamic of the process, cavitation of the liquid. The experimental hydrocannon is elaborated.
Abstract:The membership function, being a fundamental measure in the fuzzy logic theory and the associated fuzzy numbers theory, is usually determined in technical applications as a'priori given crisp values i.e. mapping R®R. Given the need for empirical determination of its value, there is a question of assessing the accuracy of the designation of its value. The authors propose the use of a modified formalism of fuzzy logic (sequential-binary approach YAAFL) and the empirical cumulative probability function for the Bernoulli distribution to determine confidence intervals for the membership function and to assess the type of probability distribution.
Abstract:The existing image segmentation algorithms do not always give expected results. Very often dedicated algorithms or tools are created for specific groups of images. An alternative solution could be to introduce a manual control over the algorithm operation. The article discusses how to use watershed algorithm for fast and hierarchical separation of large objects into smaller ones. This is implemented by using appropriate markers to define initial areas of occurrence of individual objects.
Abstract:In this paper the features of mathematical model application for research of chemical technology objects are presented. The research of chemical and technological process of soft goods treatment in the environment of organic solvents has been presented. Effective universal composition for intensification of dry-cleaning of textile materials of different fiber composition has been elaborated by means of both theoretical and experimental investigations.