One of the modern methods of reducing vibrations of plates and beams is using piezoelectric materials in the form of distributed elements or patches (applied in a passive or an active system). However, for the multimodal response of a structure, there is no possibility to place the actuators in exactly the areas with maximum curvature values for each mode. Additionally, in the case of passive multimodal suppression systems – in which energy is needed to be supplied to the system – there is the necessity to create a complicated electrical circuit. The particular electrical shunts of the circuit are tuned to the specific vibration forms which require damping. The main objective of this article is to show the possibility of creating a multimodal vibration suppression system with typical resonant shunts and proposed second slightly modified.
The proposed self-adjusting mechanism consists of a carousel rotor with a vertical axis consisting of two kinematically connected flat blades. The torque of this rotor can change the position of the directing unit and additionally the position of the main propeller in order to direct the wind stream or save the main rotor when the wind is too strong. The theory, principles of operation, and the properties of the self-adjusting system were illustrated by formulas and graphs. Based on research conducted in a boundary layer wind tunnel, the values of the aerodynamic coefficients of the flat blades were determined, and then the power and propeller torque of the rotor were found as a function of the angle of wind attack. A computational procedure provides kinematical and force relations as well as the resulting torque diagrams of the rotor. An example of the use and the design structure of a self-adjusting unit in the case of a horizontal axis wind turbine is presented.
Tungsten inert gas (TIG) welding is a multi-input and multi-output variant process. The input process parameters and other factors of welding process interact in a complicated manner and influence the weld quality – directly or indirectly. Keeping this in mind, the present work has been planned to study the impact behaviour of TIG weldment through experiments, analysis and optimization. Experimental runs have been considered as per Box-Behnken design of response surface methodology (RSM). Based on the recorded data, the mathematical models have been developed to study the effect of process parameters on impact strength. ANOVA has been utilized to identify the influence of input process parameters on the response i.e. impact strength. RSM and cuckoo search optimization (CSO) algorithm have also been applied to optimize the impact strength.
This paper presents a simple-to-use system for estimating non-measurable components of crane state vector considering parameter changes. To obtain them, it is possible to use a numerical derivative, where the measurement noise causes great inaccuracies, or the Luenberger observer and Kalman filter, which require knowledge of the dynamics of the controlled system, which is constantly changing with the crane.
Contemporary architectural transparency, understood as the optical property of the construction material, is constantly being redefined and, over the last two decades, new design trends have developed. These trends are the result of: (i) dynamic technological progress; (ii) advancement in the field of materials science; (iii) changes in the attitude of clients and users. Transparency is no longer limited to specific functions (e.g. illumination of the interior) but has become a tool of formal expression itself. This paper defines most recent trends, which are divided into two main types: (i) optical-perceptual – relying on phenomenal effects, (ii) geometrical – that differentiate the large group of spatial transformations developed from what was initially flat planar façade.
The nineteenth century was a period of ground-breaking events in the history of humanity relating to the industrial revolution, scientific discoveries, knowledge development and social changes. It was also a time when new types of commercial buildings were being formed and transformations of those that had existed for centuries were taking place. The aim of this article is to present the problems of the Central Market Hall in Budapest by Samu Pecz and compare its architectural solutions with selected nineteenth-century constructions serving the same purpose elsewhere in Europe.
This article presents a method for the quick assessment of the safety of the road on an active landslide on the Just mountain at Tęgoborze using the landslide hazard ratio of landslide movements. The hazard indicator for landslide traffic has been defined as the quotient of the largest displacements obtained from measurements using a terrestrial laser scanner to the largest displacement obtained from a numerical model of the worst geotechnical conditions and an unstable landslide. The application of this indicator was presented on the example of national road No. 75 along the section of the road in km from 51 + 900 to 52 + 700 at the location of the Just mountain at Tęgoborze in the south of Poland. The road is located on an active landslide and has a lot of traffic. The measurements were conducted with the RIEGL. VZ400 terrestrial laser scanner from 2012 to 2016. As a result of the measurements performed with a terrestrial laser scanner, a cloud of 3D points was obtained. Differential models of subsequent measurements were constructed and compared to the first base measurements. The results of 3D differential models obtained from terrestrial laser scanner measurements were compared with results obtained from 3D numerical modelling. Numerical calculations were conducted assuming the worst geotechnical conditions. The model of the landslide was fully saturated. A numerical simulation computed using the finite element method (FEM) in the MIDAS GTS program was applied. A result of the safety factor F = 0.8 (i.e. an unstable landslide) was obtained. In order to estimate the hazard, the values of the landslide hazard indicator were determined for each date using the measurements conducted with the laser scanner.
In various machining processes, the vibration signals are studied for tool condition monitoring often referred as wear monitoring. It is essential to overcome unpredicted machining trouble and to improvise the efficiency of the machine. Tool wear is a vital problem in materials such as nickel based alloys as they have high hardness ranges. Though they have high hardness, a nickel based alloy Inconel 718 with varying HRC (51, 53, and 55), is opted as work material for hard turning process in this work. Uncoated carbide, coated carbide and ceramic tools are employed as cutting tools. Taguchi’s L9 orthogonal array is considered by taking hardness, speed, feed and depth of cut as four input parameters, the number of experiments and the combinations of parameters for every run is obtained. The vibration signals are recorded at various stages of cutting, till the tool failure is observed. Taking this vibration signal data as input to ANOVA and Grey relation analysis (GRA) which categorizes the optimal and utmost dominant features such as Root Mean Square (RMS), Crest Factor (CF), Skewness (Sk), Kurtosis (Ku), Absolute Deviation (AD), Mean, Standard Deviation (SD), Variance, peak, Frequency and Time in the tool wear process.
This paper is an attempt at reconstructing Stanisław Witkiewicz’s creative method on the basis of his scattered writings. The Zakopane style has become a phenomenon across a broad spectrum of Polish national styles. The inspirations for classical national styles were typically arbitrarily selected sets of forms taken from a specific historical style associated with a given nation or state. It was often an eclectic set – enriched with elements derived from other styles. Stanisław Witkiewicz consistently avoided borrowing and copying, confining himself solely to drawing inspiration from the folk art of Podhale. In the methodology of his architecture, rational elements (exposing the structure, stressing hygiene) interweaved with ornamentation, predominantly featuring floral themes and elements of a specific mythology.