On a safety criterion for column-like structure

The practical exploitation of engineering structures needs very much a simple criterion for checking safety of structures instead of reliability index that is very difficult to be computed within the probabilistic theory. This paper deals with establishment of a simple criterion for checking safety of column-like structure based on deterministic analysis. The criterion consists of bound of the flexural displacement at the top of column that is conducted from the displacement analysis combined with ultimate state for the structure

Damage detection of beam by natural frequencies: General theory and procedure

The frequency equation of single damaged beam has been established for arbitrary boundary conditions that is the main tool for analysis as well as identification of damaged beam by using measured natural frequencies. A procedure for damage detection problem presented in this paper consists of three steps. First, the modelling error is reduced by a model updating procedure, in which the material, geometrical parameters and boundary conditions are updated. Then, measurement data are corrected based on the updated model. Finally, the damage parameters are identified using updated model and corrected measurement data. Theoretical investigation is illustrated by an example

A closed-form solution for free vibration of multiple cracked Timoshenko beam and application

A closed-form solution for free vibration is constructed and used for obtaining explicit frequency equation and mode shapes of  Timoshenko beams with arbitrary number of cracks. The cracks are represented by the rotational springs of stiffness calculated from the crack depth.  Using the obtained frequency equation, the sensitivity of natural frequencies to crack of the beams is examined in comparison with the  Euler-Bernoulli beams. Numerical results demonstrate that the Timoshenko beam theory is efficiently applicable not only for short or fat beams but also for the long or slender ones. Nevertheless, both the theories are equivalent in sensitivity analysis of fundamental frequency to cracks and they get to be different for higher frequencies

FREQUENCY ANALYSIS OF CRACKED FUNCTIONALLY GRADED CANTILEVER BEAM

In this paper, a functionally graded cantilever beam with an open crack is investigated on the base of Timoshenko beam theory; power law of functionally graded material (FGM) and taking into account actual position of neutral axis instead of the central one. The open and edge crack is modeled by coupled translational and rotational springs stiffness of which is calculated by the formulas conducted accordingly to fracture mechanics. Using the frequency equation obtained in the framework of the theory natural frequencies of the beam are examined along the crack parameters and material properties. This analysis demonstrates that sensitivity of natural frequencies of FGM beam to crack is strongly dependent on the material constants of FG

Modal analysis of functionally graded Timoshenko beam

Dynamic analysis of FGM Timoshenko beam is formulated in the frequency domain taking into account the actual position of neutral plane. The problem formulation enables to obtain explicit expressions for frequency equation, natural modes and frequency response of the beam subjected to external load. The representations are straightforward not only to modal analysis and modal testing of FGM Timoshenko beam with general end conditions but also to study coupling of axial and flexural vibration modes. Numerical study is carried out to investigate effect of true neutral axis position and material properties on the modal parameters

Natural frequency analysis of cracked beam

The model of cracked one-dimensional structure has been treated as two uniform beams connected by an equivalent rotation spring at the crack location. The frequency equation in bending vibration of the system is obtained in general form for arbitrary boundary conditions at both ends used for analysing the natural frequencies as function of crack position and magnitude. This investigation allows to carry out general procedure for identification of position as well as magnitude of the crack by natural frequencies measured experimentally

Improvement of the Membrane - less Electrolysis Technology for Hydrogen and Oxygen Generation

To provide the most efficient electrolysis process of hydrogen and oxygen generation and the electrode twain design there were studied the following:-    The process of high pressure hydrogen and oxygen cyclic generation in the membrane less electrolysis systems.-          The permissible ranges of voltage variation on the electrodes were determined depending on the electrochemical reactions taking place on the active electrode.-          There was studied the process of hydrolysis and oxidation of the active electrode hypoferrite at the corresponding half-cycles of hydrogen and oxygen release.-          There was studied the effect of variation of the distance between the active and passive electrodes onto the electrolysis process efficiency

Rayleigh's quotient for multiple cracked beam and application

Rayleigh's quotient for Euler-Bernoulli multiple cracked beam with different boundary conditions has been derived from the governed equation of free vibration. An appropriate choosing of approximate shape function in terms of mode shape of uncracked beam and specific functions satisfying conditions at cracks and boundaries leads to an explicit expression of natural frequencies through crack parameters that can simplify not only the analysis of natural frequencies of cracked beam but also the crack detection problem. Numerical analysis of natural frequencies of the cracked beam by using the obtained expression in comparison with the well-known methods such as the characteristic equation and finite element method shows their good agreement. The analytical expression of natural frequencies applied to the crack detection problem allows the result of detection to be improved

Replay detection and multi-stream synchronization in CS:GO game streams using content-based Image retrieval and Image signature matching

In GameStory: The 2019 Video Game Analytics Challenge, two main tasks are nominated to solve in the challenge, which are replay detection - multi-stream synchronization, and game story summarization. In this paper, we propose a data-driven based approach to solve the first task: replay detection - multi-stream synchronization. Our solution aims to determine the replays which lie between two logo-transitional endpoints and synchronize them with their sources by extracting frames from videos, then applying image processing and retrieval remedies. In detail, we use the Bag of Visual Words approach to detect the logo-transitional endpoints, which contains multiple replays in between, then employ an Image Signature Matching algorithm for multi-stream synchronization and replay boundaries refinement. The best configuration of our proposed solution manages to achieve the second-highest scores in all evaluation metrics of the challenge

Change in mode shape nodes of multiple cracked bar: I. The theoretical study

In present paper change in position of mode shape nodes induced by multiple cracks in bar is studied with purpose to use for the multiple crack detection from measured mode shape nodes. First, there is derived an explicit expression for natural modes in axial vibration of multiple cracked bar that allows obtaining exact positions of the node in the case of single and double crack. The change in mode shape nodes induced by multiple cracks provides an important indicator for crack localization in bar. Finally, a procedure for multiple crack detection by using mode shape nodes has been proposed and examined in an example of application