Advances in Science and Technology. Research Journal
The paper deals with approximations of random sums. By random sum we mean a sum of random number of independent and identically distributed random variables. Distribution of this sum is called a compound distribution. The model is especially important in non-life insurance. There are many methods for approximating compound distributions, one of the most popular one is approximation with shifted gamma...
The paper presents CFD analysis of fuel flow in the CNG injector. The issues such a pressure drop along an injector channel, mass flow through the key sections of the injector geometry, flow rates, the impact of the needle shape on the deflection of the sprayed gas cone and the impact of the wall head are analyzed in the article. The simulation was made in the transient states conditions for full...
The article presents the results of studying the effects of technological parameters of milling upon surface roughness and microhardness of C45 steel objects after laser cutting. The metallographic structure formed as an effect of cutting by laser was also analyzed. The milling was performed on a FV-580a vertical machining centre. Depth of cut and feed per tooth were changed within the following range:...
The determinants method of explanatory variables set selection to the linear model is shown in this article. This method is very useful to find such a set of variables which satisfy small relative error of the linear model as well as small relative error of parameters estimation of this model. Knowledge of the values of the parameters of this model is not necessary. An example of the use of the determinants...
This paper investigates the mechanism of origin of structural, structural and technological defects of rollers. The technique for integrated indicator of vibration working surfaces of the rings to determine the level of life of the finished part to the operation as part of the bearing and predict the vibroacoustic characteristics of rolling bearings. It was established that technological defects cause...
Recent demand for powering small sensors for wireless health monitoring triggered activities in the field of small size efficient energy harvesting devices. We examine energy harvesting in an aluminium beam with a piezoceramic patch subjected to kinematic harmonic excitation and impacts. Due to a mechanical stopper applied, inducing a hardening effect in the spring characteristic of the beam resonator,...
The study presents issues concerning technical solutions of combined systems of energy generation which can be used primarily in low-level power plants, installed in various types of public utility sites. A detailed description is given of selected ways of powering combined energy generation systems, presenting conceptual outlines of their operation and information on their advantages, disadvantages...
Mobile adhoc network is self-configurable and adaptive. Due to node mobility we cannot predict load on the network which leads to congestion, one of the widely researched area in manets. A lot of congestion control techniques and metrics have been proposed to overcome it before its occurrence or after it has occurred. In this survey we identify the currently used congestion control metrics. Through...
Steel bars are manufactured in the rolling process, whereby they are characterized by strain hardening and poor plastic properties. In many application cases such properties are improper, therefore, additional heat treatment is required. Crucial influence on the products quality after heat treatment has an appropriate selection of process parameters. In many modern technologies of heat treatment the...
The article presents studies of selected physical and mechanical properties of hybrid materials type of polymer-metal. In the frame of this work modification of PVC with the iron and copper powder in amount of 0, 1.5 and 3% and blowing agent in amount of 0, 0.5, 1% was done. Extrudates in a form of pipe were tested to determine density, porosity, maximum tensile stress, stress at break, modulus of...
Due to the problem that represents the accelerated production of waste from the consumption of polyethylene terephthalate (PET), it becomes necessary to look for alternative solutions; chemical recycling is a suitable method for conversion into a material with potential application in concrete additive, such as unsaturated polyester resins; with the above improvements and conservation of non-renewable...
A watershed-based region growing image segmentation algorithm requires a fast watershed-based dilation implementation for effective operation. This paper presents a new way for watershed image representation and uses this representation for effective implementation of dilation. Methods for improving the algorithm speed are discussed. Presented solutions may also be used for solving other problems...
In the last few years a significant growth of three-dimensional printing has been no-ticed. Although 3D printers have been around for about 30 years, they were very ex-pensive, that is why they were available in the industry only in the majority . In recent years, prices of 3D printers have fallen more than tenfold, owing to the fact they are used not only in large enterprises but also in all kinds...
Modern education opens up broad prospects for the use of the Internet and its applications. Global computer network helps us to cross all limits allowed for the development and transfer of knowledge and to stimulate and create personal skills. Time and distance are no longer an obstacle. Recently, it has also been popularized in the use of online tools for professional work and intellectual and to...
The article presents the possibility of using a computer with specialized software to support education of students with communication disorders. It also presents the results of preliminary tests based on the original program developed for students with intellectual disabilities in moderate and significant degree of disability in the field of alternative communication with using pictograms and pcs.
This work discusses computational capabilities of the programs belonging to the CAS (Computer Algebra Systems). A review of commercial and non-commercial software has been done here as well. In addition, there has been one of the programs belonging to the this group (program Mathcad) selected and its application to the chosen example has been presented. Computational capabilities and ease of handling...
Modelling and calculations of a contact layer between elements joined in a preloaded bolted connection for the operational condition are presented. The physical model of the bolted connection is based on a flexible flange element that is joined with a rigid support by means of the no-bolt model (at the assembly stage) or the rigid body bolt model (at the operational stage). The contact layer between...
Machining process nowadays could not be conducted without its inseparable element: cutting edge and frequently numerically controlled milling machines. Milling and lathe machining centres comprise standard equipment in many companies of the machinery industry, e.g. automotive or aircraft. It is for that reason that tertiary education should account for this rising demand. This entails the introduction...
In this paper we introduce a transformation group connected with Poncelet’s porism. Several open questions following from our considerations end the paper. The aim of this paper is to give a new approach to find an algebraic Fuss-type formula for all natural n>2. Developed method may be applied to investigations of Poncelet’s porism.
The article presents the issue of emotion recognition based on polish emotional speech analysis. The Polish database of emotional speech, prepared and shared by the Medical Electronics Division of the Lodz University of Technology, has been used for research. The following parameters extracted from sampled and normalised speech signal has been used for the analysis: energy of signal, speaker’s sex,...