Influence of Grain Shape in Grinding Wheels on the Machining Quality of Bearing Rings

The quality of grinding of bearing races is related to their performance and durability. The aim of this work is to establish how the machining quality of bearing rings depends on the characteristics of grinding wheels, in particular, on such a parameter as the shape of abrasive grains. Several batches of experimental grinding wheels were made, containing grains of different shapes (from isometric to lamellar varieties). Quantitatively, the shape of the grains was estimated by the shape factor parameter (SF), which is equal to the ratio of the diameters of inscribed and circumscribed circles in the contours of the used grains. The shape factor was determined using a scanner or a digital microscope and a special computer program. The tests were carried out on circular, plunge, and finishing grinding, using coolant, on a SIW 4E machine in a bearing factory. The machining quality of the bearing rings was assessed by studying the microstructure, microhardness and roughness of their bearing races. The durability of grinding wheels was determined by the number of machined rings before maximum tool wear. It has been established that by a differentiated approach to the choice of grain shapes in the wheel, it is possible to significantly increase its operational capabilities: increase the microhardness of the ground surfaces, reduce the roughness of processing, and increase the durability of grinding wheels.

Patterns of coloring with ionic dyes of the base glass matrix and enamel coatings in the system R2O–ВаО–ZnO–Al2O3–В2О3–TiO2–SiO2

The paper presents the study on the identification of patterns of coloring of a basic glass matrix and enamel coatings based on it in the system R2O–ВаО–ZnO–Al2O3–В2О3–TiO2–SiO2 by a number of ionic dyes. Regardless of the dye content, ionic dyes give the same color tone to both glasses and coatings based on these glasses as follows: CuO (1.0–3.0 wt.%) =489–494 nm (blue-green), Fe2O3 (0.5–2.0 wt.%) =575–585 nm (yellow), K2Cr2O7 (0.5–2.0 wt.%) =570–576 nm (yellow-green), CoO (0.5–1.0 wt.%) =441–463 nm (blue-violet), and NiO (0.5–1.0 wt.%) glass=559'–571' nm, coatings=598–629 nm (brown). It is shown that according to the degree of color intensity of glasses and coatings based on them, the dyes are arranged in the following sequence: CoO>NiO>CuO>K2Cr2O7>Fe2O3.. The research was conducted using a special computer program COLOR GLASS. The established patterns are used in the development of lead-free glass enamels for jewelry and decorative products.

Strengthening and performance assessing historical cinema hall balcony according to new Turkish Earthquake Code

Strengthening historical buildings and evaluating their performances make great contributions to both the history of the country and the tourism of the country. In this study, performance analysis and evaluations of the historical cinema hall balcony, which was built in 1933 by a French company and served to Zonguldak province for a long time, are presented in detail. This cinema hall was frequently used by local people between 1933 and 1999 and hosted many Yeşilçam movies. Firstly, examinations were performed in the historical cinema hall and the areas (columns, beams and floors) that were damaged in time were identified. According to the obtained information, it was determined that there were significant damages in the carrier system of the building and there were visible cracks and damages in the columns of the cinema hall. It was also observed that explosions occurred in one of the main carrier columns of the balcony. After the core samples taken from the balcony were tested in the laboratory, the current status of the carrier elements and reinforcements were determined with the help of an x-ray rebar scanner. After all these processes, the structure was modeled as three dimensional (3D) using a special computer program and performance evaluations were performed regarding the current state of the structure. As a result of the performance evaluation, it was determined that the balcony of the historical cinema hall could not survive anymore and would collapse over time. It was concluded that there were great damages especially on the balcony columns and a reinforcement should be made on a total of 6 columns. Strengthening was made to 4 different main columns and a performance analysis was performed again in strengthened structure. After strengthening, it was understood that the columns of the balcony of the cinema hall could survive for a long time.

Effective Gap Size Index for Determination of Optimum Separation Distance Preventing Pounding between Buildings during Earthquakes

Seismic excitations may lead to collisions between adjacent civil engineering structures, causing major damage. In this paper, an effective equation for calculating the gap size index is proposed so as to provide the optimum separation distance preventing structural pounding during different earthquakes. Evaluation of the best prediction of the required separation distance between two adjacent buildings was carried out by using the lumped mass multi-degrees of freedom models of structures. A special computer program was used to perform dynamic analyses in order to confirm the accuracy of the proposed formula. For this purpose, several different models of buildings with various properties under different earthquake excitations were analyzed. The results of the study clearly show that the proposed formula for the gap size index (based on vibration periods and damping ratios of buildings) is effective and it allows us to calculate the optimum separation between adjacent structures preventing their pounding during different earthquakes.

The Complexity Assessment Method of Logical Reasonings

The development of methods for assessing the various didactic characteristics of teaching texts and teacher messages is an urgent problem of modern teaching theory. Its solution allows to rank texts (descriptions, proofs, explanations, etc.) according to the degree of complexity, and this helps to optimize the learning process and increase the objectivity of assessing students' knowledge. In general, educational texts contain a descriptive-narrative and logical component; the share of the latter can be defined as the ratio of informative content of logical reasonings to the overall informative content of the text. The complexity (informativity) of the text can be found as a sum of the com-plexities of its constituent scientific terms and ordinary words. The semantic complexity of the term relative to the Z0 thesaurus is equal to the number of words that need to be spoken to explain the term to a student with the thesaurus Z0. It should be noted that each new mention of the term reduces its contribution to the overall complexity of the text. The proposed method for assessing the complexity of logical reasonings involves: 1) identifying all facts and logical rules used, the complexity of which exceeds the cho-sen level of knowledge; 2) expanding the text by adding all the statements necessary for conducting reasonings; 3) creation of text file text.txt containing verbal part of educa-tional text and verbally encoded formulas and figures; 4) creation of a dictionary (slo-var.txt file) containing the scientific terms used with indication of their level of com-plexity; 5) analysis of the text.txt file using the special computer program addressing to the dictionary which allows to determine the overall semantic complexity of the eva-luated text; 6) isolating logical reasonings from the text and determining their total complexity; 7) finding the share of logical reasoning in the text. The complexity of four text fragments was estimated, for which the share of logical reasonings and the average coefficient of information folding were calculated.

Didactic Complexity Evaluation of Theorems Proofs of the School Geometry Course

In the study of geometry, the student’s assimilation of the reasonings carried out in the theorems proofs has great importance. The diffi culty of understanding reasonings depends on the number of logical links, terms diversity and semantic complexity of mathematical statements. The article proposes the method for determining the didactic complexity of the theorems proofs and the results of its application. The essence of the method consists in “measuring” the amount of semantic information in theorem formulation, picture, reasonings and multiplication of the received volume with the diversity indicator of the terms used. For this, the theorem statement, the picture and the actual proof should be presented in text form, and the resulting file should be analyzed using a special computer program which calculates the number of diff erent terms in this text, takes into account their complexity, and fi nds the diversity indicator. The expert estimates complexity of terms by counting the words included in its defi nition and by the method of paired comparisons. An assessment of 12 frequently used theorems was carried out; this allowed them to be ordered by complexity. For each theorem the proof volume, the total amount of semantic information in it, the terms diversity indicator, the logical reasoning number, the information folding coeffi cient and the didactic complexity were determined.

3D VISUALIZATION TECHNOLOGY

Three-dimensional (3D) visualization is the process of creating the three-dimensional object using a special computer program. Today computer graphics technologies such as 3D visualization technology are becoming more and more in demand. The technology has earned popularity among designers because it allows creating three-dimensional objects of any shape. It is widely used throughout the world to create the interiors of houses, offices, hotels, etc. This paper provides a brief introduction to 3D visualization.

Non-linear non-radial oscillations of the self-gravitating disk taking into account halo

In this work, we have studied by numerical methods the evolution of non-radial oscillations of an unsteady disk, which is surrounded by a passive ellipsoidal halo with a uniform density. For this purpose, we have developed a special computer program. Numerical calculations are performed for various values of the system parameters, such as the initial perturbation, the circular speed of rotation of the disk, and the ratio of the halo mass to the disk mass. For each of the possible cases, a statistical amplitude is determined that characterizes the degree of deformation of the system. The critical values of the system parameters are found at which the halo stabilizes the non-linearly non-radial oscillations of the disk subsystem of galaxies at an early stage of their evolution.

Archaeological methods and innovations in the post-Soviet area through eyes of archaeologists

The history of archaeological method and innovation during the post-war and contemporary periods has been studied not enough in the post-Soviet area. But this topic is actual because at that time achievements of the scientific-technical revolution have been implemented into archaeology. The aim of the article is to study the method of primary data processing (information collection at the time of excavation, an office study of artifacts and preparation of a report on the archaeological excavation) and innovation to this process in the Soviet and post-Soviet archaeology. The research is based on 7 interviews with archaeologists from Kyiv, Moscow and St. Petersburg which have been recorded by the author. On the respondents’ opinion for the last 15 years modern digital technique as digital cameras, GPS and laser tacheometers has been used in the post-Soviet area and non-invasive methods of archaeological research have spread at the last time. In the USSR field lists of artifacts were filled manually at the beginning then it was made by personal computers. An approach to anthropological materials selection has been changed since the Soviet time and cooperation with natural scientists has been widespread in the field. Since 1970s Soviet archaeologists have made attempts to create data bases. Initially matrix tables were used for this then it was realized by computers. These works were provided in Moscow and Kyiv but the progress was made only after appearance of modern PC. A special computer program has been developed for burial sites of the Bronze Age which is in use till now. In the Soviet time the quality of reports on the archaeological excavation depended on funding and other sources of researchers and research establishments. And the most difficult work was preparation of field drawings for final reports. PCs were in use for working with texts at the beginning and after some time for processing of graphic materials. It made the archaeologists’ work simpler. Today modern technologies help to fix artifacts better in the field and to process primary data. But there are problems with comparison of results because of different equipment status of scholars. Moreover, one respondent expresses an idea that computers have made work easier but they have not led to a revolutionary breakthrough directly in archaeology.

The Dynamics of Surface Forest Fire and Forest Fuel Ignition Under the Heat Radiation From the Fire Line

The chapter presents the results of experimental-analytical modeling of the surface forest fire dynamics and the process of forest fuel ignition when exposed to thermal radiation from the fire line. The regularities are established for the occurrence and spread of fires in natural ecosystems of the temperate climatic zone. Analytical solutions have been obtained that make it possible to predict the level of heat load on the soil cover of coniferous stands. The special computer program has been developed to calculate the heat load during fires. The methods of field and laboratory modeling revealed patterns of forest fuel heating and ignition depending on moisture content. A practice-oriented method is proposed to calculate the width of fire barriers that limit the spread of forest fires. The methods for creating fire barriers are proposed.