Wyniki wyszukiwania - BazTech

1

Making glass flatness a standard

Lohrer Diana, Martinez Juan Pablo

Świat Szkła

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2024

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R. 29, nr 1

1--4

2

Impact of single-piece flow thermo-chemical treatment process conditions on hole quenching deformation

Stachurski Wojciech, Sawicki J., Zgórniak P., Wołowiec-Korecka E.

Archives of Materials Science and Engineering

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2023

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Vol. 121, nr 1

18--24

EN

Purpose: Pulsed low-pressure carburizing (LPC) and omnidirectional high-pressure gas quenching (HPGQ) are innovative methods for quenching the surface layer. The thermo-chemical treatment carried out by this method reduces quenching geometric deformations, with detailed numerical values not available in the literature due to the short existence of this method. Design/methodology/approach: Sixteen toothed elements of EN 20MnCr5 steel were subjected to pulsed low-pressure carburising with omnidirectional jet quenching in 4 groups, varying the process temperature (920°C, 960°C) and in two groups performing a tempering treatment. The elements were tested before machining by measuring their internal hole diameters, radial runout, roundness and cylindricity. These values were tested again after treatment. The direction of change and the statistical significance of the effect of treatment and its parameters, temperature and tempering were analysed. Findings: Thermo-chemical treatment significantly affects geometric changes in diameters, roundness, cylindricity and radial runout compared to elements without heat treatment due to physical transformations occurring during this treatment (p<0.05). Changing the process temperature in the value range of 920°C-960°C affects the hole diameter (makes it smaller) (p<0.05), but does not affect radial runout, cylindricity and roundness. The observed dimensional changes in diameters have numerically small values (<0.005 mm). The tempering treatment can affect the values of average diameters. Its effect on roundness, cylindricity and radial runout was not observed. Research limitations/implications: In the temperature range studied, the method of pulsed low-pressure carburising + omnidirectional high-pressure gas quenching makes it possible to raise the temperature of the process and shorten its duration without significant geometric changes in the treated elements. Practical implications: The method of pulsed low-pressure carburising and omnidirectional high-pressure gas quenching (HPGQ) ensures the maintenance of reproducible quenching deformations at a level significantly lower than conventional processing methods. Originality/value: The method of pulsed low-pressure carburising together with omnidirectional high-pressure gas quenching (HPGQ) is a method that has been used briefly in the industry, and there are few reports on it to date.

3

Distortion Analysis of Thin-Walled Investment Castings

Mandal R., Roy Soumyajit, Sarkar Subhajit, Mandal T., Pramanick A. K., Majumdar G.

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 3

59--60

EN

Dokra casting is famous for its Artistic value to the world but it is also sophisticated engineering. The technique is almost 4500 years old. It is practiced by the tribal artisans of India. It is a clay moulded wax-based thin-walled investment casting technique where liquid metal was poured into the red hot mould. Dimensional accuracy is always preferable for consumers of any product. Distortion is one of the barriers to achieving the accurate dimension for this type of casting especially for the bending parts. The cause and nature of the distortion for this type of casting must be analyzed to design a product with nominal tolerance and dimensional accuracy.

4

Identyfikacja i modelowanie zniekształceń budynku zabytkowego na podstawie chmury punktów

Pawłowicz Joanna A.

Materiały Budowlane

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2022

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nr 11

60--62

PL

Obiekty zabytkowe są często skomplikowane, co utrudnia pomiar i identyfikację zniekształceń. Z pomocą przychodzi technologia skaningu laserowego 3D, która w szybki sposób pozwala na zebranie danych geometrycznych dotyczących budynku. Efektem jest uzyskanie chmury punktów, którą poddano analizie z wykorzystaniem oprogramowania Leica Cyclone, AutoCad i ReCap. To studium przypadku pokazuje, że skaning laserowy z powodzeniem może być wykorzystywany w identyfikowaniu zniekształceń występujących w budynkach.

EN

Historic objects are often complex, which makes it difficult to measure or identify distortions. The technology of 3D laser scanning comes to the rescue, which allows you to quickly collect geometric data about the building. Its effect is to obtain a point cloud, which was analyzed using Leica Cyclone, AutoCad and ReCap software. This case study shows that laser scanning can be successfully used to identify distortions in buildings.

5

Proposed single-zone map projection system for Turkey

Yildirim Faruk, Kadi Fatih

Reports on Geodesy and Geoinformatics

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2021

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Vol. 112

35--45

EN

The coordinate base of the maps or sheets produced is the Universal Transversal Mercator (UTM) conformal projection, and it is not possible to work in a single coordinate system in Turkey. Therefore, a transition from UTM to other conformal projections is required. For the countries extending in an east–west UTM zone width like Turkey, composite projection (CP), a double standard paralleling Lambert Conformal Conic (LCC) and double map projections (DP) are used widely. However, this process causes increase in working load and processing errors by users. This study aims to determine a common projection system that can be used in the whole country. In this context, a composite projection from UTM and LCC projection has been defined for the first time. According to the results obtained, map projection CP with the least distortion values in both east–west and north–south directions has been chosen. With the CP selection, a single coordinate system has been determined for medium- and large-scale maps. Projection correction formulas, scale factor and false origin have been determined for map coordinates in CP. These distortions are obtained with a difference of less than 1 cm for 1 km long sides and less than 0.003″ for the azimuth value of this side, when the correction formulas are used.

6

Analysis of material property models on WAAM distortion using nonlinear numerical computation and experimental verification with P-GMAW

Manurung Yupiter H. P., Prajadhiana Keval P., Adenan Mohd Shahriman, Awiszus Birgit, Graf Marcel, Haelsig Andre

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 1

533--545

EN

This fundamental research deals with the investigation of material property model influences on distortion induced by multi-layered Wire Arc Additive Manufacturing (WAAM) with synergic-pulsed gas metal arc welding (P-GMAW) process which was modelled and simulated by means of non-linear numerical computation. The material property models of stainless steel SS316L component to be compared stem from three different sources namely existing database, initial wire and evolved component. The new property models were generated with advanced material modelling software JMATPRO based on chemical compositions analysed at initial wire and component using SEM–EDX. The flow curve for each material model was taken with the strain rates ranging from 0.001 to 1.0 s−1. In the numerical simulation, a coupled thermomechanical solution was adopted including phase-change phenomena defined in latent heat. Goldak’s double ellipsoid was applied as heat source model and simplified rectangular bead with hexagonal element type and meshing was developed to avoid extensive pre-processing effort and to reduce the computational time at post-processing level. Temperature behaviour due to the successive layer deposition was simulated considering heat transfer effect coupled to mechanical analysis. The adjustment of simulative transient to experimental thermal distribution lead to new fitted heat transfer coefficient. Prior to execution of numerical simulation, a sensitivity analysis was conducted to find the optimal number of elements or mesh size towards maximum reached temperature. It can be concluded based on the adjusted model, selected mesh size and experimental validation that numerical computation of substrate distortion with evolved material property of component and initial wire of SS316L yield closer average result within the relative error ranging between 11 and 16% compared to database material giving more than 22%.

7

The influence of quenching temperature on distortions during the individual quenching method

Wołowiec-Korecka E., Stachurski W., Zgórniak P., Korecki M., Brewka A., Byczkowska P.

Archives of Materials Science and Engineering

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2020

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Vol. 105, nr 2

80--85

EN

Purpose: In this paper, the impact of hardening temperature on the quenching distortions which occur during low-pressure carburizing with gas quenching - using the individual quenching method - was analysed. Design/methodology/approach: The reference elements were subjected to carburizing at 980°C, followed by gas quenching at temperatures of 860°C, 920°C and 980°C. The geometrical measurements of the elements were made before and after the chemical treatment and the size of the quenching distortions of their geometrical parameters was determined. Findings: It was demonstrated that a high temperature of quenching has an unfavourable effect on changes in cylindricity and roundness parameters but, at the same time, reduces the size of distortion of outer parameters. Low temperature quenching reduces quenching distortions of cylindricity and roundness parameters while increasing the distortion of outer dimensions. Research limitations/implications: Based on the research and analysis carried out in this work, it was found that the use of lower quenching temperature is justified in economic and quality terms. Practical implications: In the case of the aviation or automotive industry, very high quality of manufactured elements along with a simultaneous reduction of their production costs is extremely important. Maintaining the dimensions of the elements during heat treatment is extremely difficult. The tests allowed to determine the optimal hardening temperature, which brings with it acceptable deformations. Since it is easier to “repair” the outer geometrical dimensions (diameter, thickness), it seems that quenching from lower temperatures is a more favourable process. Originality/value: The conducted tests allowed to determine the most favourable conditions for hardening elements from the automotive industry, taking into account the occurring deformations and their subsequent processing

8

Finite beam element with 22 DOF for curved composite box girders considering torsion, distortion, and biaxial slip

Zhu Li, Wang Jia-Ji, Li Ming-Jie, Chen Chao, Wang Guang-Ming

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 4

16--34

EN

Experimental and numerical study on the mechanical performance of curved steel–concrete composite box girders is reported in this research. First, this research establishes a theoretical model for curved composite girders with 11° of freedoms (DOFs) for each node. The DOFs include the longitudinal displacement, transverse displacement, deflection, torsion angle, warping angle, and interface biaxial slip between steel and concrete. Based on the virtual work theorem, the equilibrium function, the stiffness matrix, the node displacement matrix and the external load matrix are proposed for the curved composite girders using the FE spatial discretization. Second, the authors conduct an experimental program on three large-scale curved composite girders with various interface shear connectors and central angles. The comparison between the developed finite beam element, the elaborate FE model and the test results indicates the developed finite beam element has an adequate level of accuracy in predicting the deflection, the torsion angle and the axial strain distribution of test specimens. Third, based on the developed finite beam element model, the effect of initial curvature, number of diaphragms, and the interface connector stiffness on the curved composite girder is examined. The simulation results showed that the initial curvature significantly contributes to the displacement and stress of composite girders. Applying more diaphragms can notably reduce the distortion angle and distortion displacement. The interface shear connector stiffness has a significant influence on the curved composite girder. With the increasing shear connector stiffness, the displacement and stress of curved composite girders decrease notably. Based on the parametric analyses, it is recommended to limit the central angle of simply supported composite girder below 45°, to apply an adequate number of diaphragms, and to design curved composite girders as fully shear connection specimens.

9

Effect of 50 Hz magnetic field on chicken embryo development and course of hatching

Lis Marcin W.

Science, Technology and Innovation

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2019

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Vol. 5, no. 2

44--49

EN

The effect of additional extremely low frequency (ELF) magnetic field (50 Hz) on the development of chick embryo was investigated. The experiment was carried out in three variants for induction values 15, 10 or 5 μT. Magnetic field (MF) in the experimental incubator was generated by a set of three Helmholtz coils. The following analyses were performed: embryopathological analysis; evaluation of the hatched chicks for quality; analysis of the course and synchronization of hatching Early embryo mortality in groups exposed to MF 10 and 15 μT compared to the control was higher by about 3 percentage points. Simultaneously, in these groups the hatching processes accelerated, but the quality of hatched chicks was much lower.

10

Cryptosystems using subgroup distortion

Chatterji I., Kahrobaei D., Lu N. Y.

Theoretical and Applied Informatics

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2017

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Vol. 29, No. 1-2

14--24

EN

In this paper we propose cryptosystems based on subgroup distortion in hyperbolic groups. We also include concrete examples of hyperbolic groups as possible platforms.

11

Pomiar wielkości poboru energii elektrycznej w warunkach znacznych zakłóceń

Bałuka G.

Wiadomości Elektrotechniczne

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2016

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R. 84, nr 9

17--20

PL

Przedstawiono efektywną metodę dokładnego pomiaru wielkości energii elektrycznej w sieciach, w warunkach znacznych zniekształceń przebiegów napięć i prądów, gdy przebiegi napięć i prądów mają charakter procesów stacjonarnych lub quasi-stacjonarnych.

EN

The paper presents the effective method of precise measurement of electric power in grids under conditions of considerable perturbations of voltage and current, when voltage and current function shape shave stationary or quasi stationary character.

12

Analysis and comparison of symmetry based lossless and perceptually lossless algorithms for volumetric compression of medical images

Chandrika B. K., Aparna P., Sumam D. S.

Journal of Medical Informatics & Technologies

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2015

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Vol. 24

147--154

EN

Modern medical imaging techniques produce huge volume of data from stack of images generated in a single examination. To compress them several volumetric compression techniques have been proposed. Performance of these compression schemes can be improved further by considering the anatomical symmetry present in medical images and incorporating the characteristics of human visual system. In this paper a volumetric medical image compression algorithm is presented in which perceptual model is integrated with a symmetry based lossless scheme. Symmetry based lossless and perceptually lossless algorithms were evaluated on a set of three dimensional medical images. Experimental results show that symmetry based perceptually lossless coder gives an average of 8.47% improvement in bit per pixel without any perceivable degradation in visual quality against the lossless scheme.

13

Accelerated image quality estimation based on the Monte Carlo approach for various types of image distortions

Okarma K.

Poznan University of Technology Academic Journals. Electrical Engineering

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2010

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No. 63

157-165

EN

In the paper the application of the Monte Carlo method for the fast estimation of image quality is investigated. Taking into account the variety of possible distortions present in the images, probably the largest publicly available database of 1700 images with 17 types of distortions has been used for the practical verification of the proposed approach. The analysis has been performed for some of the "state-of-the-art" image quality metrics as an alternative to the classical ones together with the comparison to well known Peak Signal to Noise Ratio.

14

Deformations and decrease of load-carrying capacity of welded structures due to residual welding stresses

Farkas J., Jarmai K.

Foundations of Civil and Environmental Engineering

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2006

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No. 7

117-126

EN

Residual deflection due to restrained shrinkage of longitudinal welds is calculated in the case of an asymmetric I-section crane runway girder. The residual welding compression stresses decrease the load-carrying capacity of a welded I-section compression strut in a significant measure. The effective width of a welded stiffened plate should be calculated considering residual welding stresses. The fatigue strength of welded joints is influenced by residual welding stresses significantly. These effects are illustrated by numerical examples.

15

Pulsacje napięcia wyjściowego prądnicy pokładowej prądu stałego źródłem informacji diagnostycznej o stanie układu napędowego.

Gębura A.

Zagadnienia Eksploatacji Maszyn

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2003

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Vol. 38, nr 1

187-201

PL

W pracy omówiono opracowaną przez autora i wdrożoną pod jego kierunkiem metodę diagnostyczną opartą na pomiarze i analizie parametrów składowej pulsacji prądu stałego. Zastosowanie tej metody wymagało zgłębienia fizyki zjawisk powstawania składowej przemiennej sygnału wyjściowego prądnicy komutatorowej - część niniejszego opracowania jest poświęcona pewnym zjawiskom stwierdzonym podczas badań. Przedstawiono materiał badawczy otrzymany z badań laboratoryjnych zespołu napędowego LUZES-III, w którym rolę "prądnicy-obserwatora" pełniła lotnicza prądnica GSR-ST-12000WT. Równocześnie wykazano, że zmiany częstotliwości składowej pulsacji prądnicy prądu stałego są dyskretnym odzwierciedleniem zmian prędkości kątowej badanych par kinematycznych napędów lotniczych.

EN

The author is keen on exchanging experience relating to a method described scientifically and developed in Air Force Institute of Technology. The method has been named FDM-A (F-frequency, M-modulation, D-direct current, A-level of method advance). Power transmission tracks of various aircrafts usually exhibit different degrees of wear and tear. A diagnostic method based on the measurement of D.C. generator's frequency modulation varying component pulsation has been developed at the Air Force Institute of Technology. This method makes it possible to qualify the level of usual wear-and-tear of subassemblies and locate the defects during operation of the aircraft power transmission tracks. Algorithms of a quick and effective analysis of wear-and-tear for particular kinematic couples have been worked out. Basing on this method, a few prototypes of pocket the size testers were produced six years ago. They are combined with aircraft electric network and indicate the most worn subassemblies, as well as the level of wear-and-tear. At present, the diagnostic system based on measurements taken with these testers and furnished with a suitable computer database would increase the reliability of the whole aircraft systems. Until now, a diagnostic level has been qualified only on the basis of the so-called negative standard power transmission track, with at least one extremly worn-out element, and only for one aircraft type. Theoretical and experimental works go on simultaneously, with the aim to establish a more universal method. An airborne D.C. generatoris used as a converter. Diagnostic equipment is connected to a live terminal which provides the diagnosis of elements in a few minutes.