DEVELOPMENT OF A PROCEDURE FOR INCREASING THE ACCURACY OF THE RECONSTRUCTION AND TRIANGULATION PROCESS OF THE CRANIAL VAULT GEOMETRY FOR ADDITIVE MANUFACTURING

CT scanners installed in clinics used different slice thicknesses, which usually produce data with an anisotropic structure of voxels. The low visual quality results are due to the discontinuous interpolation between neighboring voxels, resulting in a very “blocky” appearance of the reconstructed surfaces (stair-step artifact). This structure can also directly affect the volume, geometry, and linear accuracy of digital and physical 3D models. The article presents a method that improves the design of cranial vault models for additive manufacturing after the staircase artifact has occurred. The research was performed on 14 different patients (seven males and seven females). Changing the slice thickness from 2.4 mm to 4.8 mm generated over 90% errors in reconstructing the cranial vault area in the range of 0.830 mm +/- 1.364 mm (mean deviation +/- expanded uncertainty) for males and 0.780 mm +/- 1.338 mm for females. To increase the spatial resolution of the digital imaging data, an interpolation process was performed on 2D radiographic images. After using the data interpolation procedure (Lanczos filter), deviations were mainly in the range of 0.465 mm +/- 1.038 mm for males and 0.328 mm +/- 0.842 mm for females. The last stage of the improved process involved mesh optimization. Utilizing Laplacian smoothing surface and isotropic polygonal remesh, this procedure decreased global error, especially in regions with high curvatures. Over 90% of the analyzed points after using the Lanczos filter and optimization mesh procedure are within the range of 0.338 mm +/- 1.014 mm for males and 0.301 mm +/- 0.806 mm for females

Determining the Assumptions for the Selection of Measurement Methods for Products Manufactured with Incremental Methods

The article presents the method of determining the assumptions for the selection of measurement methods for products manufactured with the use of incremental processes. In the research area, an analysis of 3D printing methods was carried out in terms of the specificity of the additive process, the materials used, the possibility of process deformations, and the accuracy of technological machines. With regard to the measurement methods, the analysis covered the accuracy of the method, the speed of the measurements, the costs of the measurements and the applicability to additive manufactured products. As a result of the analysis, assumptions were made for the criteria for selecting measurement methods for incrementally manufactured objects. The accuracy of prototyping in incremental processes largely depends on the accuracy of their numerical models. Taking this into account, simulations and studies of program processing of data were also carried out, starting from the development of a 3D-CAD model, through the export of numerical models and the preparation of data for manufacturing and control-measurement processes

Snow distribution patterns on Svalbard glaciers derived from radio-echo soundings

The spatial distribution of snow thickness on glaciers is driven by a set of clima− tological, meteorological, topographical and orographic conditions. This work presents re− sults of snow accumulation studies carried out from 2006 to 2009 on glaciers of different types: valley glacier, ice plateau and ice cap. In order to determine snow depth, a shallow ra− dio echo−sounding method was used. Based on the results, the following snow distribution patterns on Svalbard glaciers have been distinguished: precipitation pattern, precipita− tion−redistribution pattern, redistribution pattern and complex pattern. The precipitation pattern assumes that the snow distribution on glaciers follows the altitudinal gradient. If the accumulation gradient is significantly modified by local factors like wind erosion and redeposition, or local variability of precipitation, the accumulation pattern turns into the precipitation−redistribution pattern. In the redistribution pattern, local factors play a crucial role in the spatial variability of snow depth. The complex pattern, however, demonstrates the co−existence of different snow distribution patterns on a single glacial object (glacier/ice cap/ice field)

The Place of 3D Printing in the Manufacturing and Operational Process Based on the Industry 4.0 Structure

The article presents the place of 3D printing in the manufacturing and operational process. It analyzes selected incremental technologies in the product life cycle. It describes selected processes for testing the properties of materials used in 3D printing, including accelerated aging tests and simulation of operating conditions. Areas of application of 3D printing were defined, starting from design and prototype development through manufacturing of technological tools and finally finished products. Design criteria of additivelymanufactured elements in relation to the exploitation process are discussed. A methodology for the development of 3D-CAD models of manufactured elements, software processing of data and data storage format for manufacturing products and spare parts is presented. The assumptions of repair procedures based on the production of spare parts by means of 3D printing in relation to data circulation compatible with the idea of Industry 4.0 structure have been adopted

Modelling of the injection and combustion processes in the gasoline direct injection engine

Rad prikazuje modeliranje procesa ubrizgavanja pomoću KIVA programa. Složeni matematički modeli koji se koriste u izračunima i koji opisuju procese koji se odvijaju unutar cilindra motora omogućuju generiranje kompliciranih virtualnih modela koji odražavaju stvarne uvjete na zadovoljavajući način. Točnost rezultata proračuna određena je kvalitetom ulaznih podataka, koji se mogu dobiti na temelju ispitivanja s modelom. Na temelju modeliranja procesa ubrizgavanja i izgaranja u GDI motoru, predstavljenih u radu, dobivena je osnova za širu analizu plinsko-dinamičkih pojava.The paper presents modelling of the injection process by means of KIVA program. The elaborate mathematical models used in calculations describing the processes occurring inside the engine cylinder make it possible to create complicated virtual models reflecting real conditions in a satisfactory way. The accuracy of calculation results is determined by the quality of input data, which can be obtained based on model investigations. Based on the modeling of injection and combustion processes in the GDI engine, presented in the work, the basis for a broader analysis of the gas-dynamic phenomena was obtained

Numerical analysis of the engine with spark ignition and compression ignition

U radu se prikazuju istraživanja simulacije izgaranja u testiranom motoru s četiri cilindra, na osnovu motora Toyote Yaris 1,3 dm3 s paljenjem iskrom i opremljenim s dva sustava napajanja energijom: osnovnim i paljenjem. Primijenjene su dvije metode pokretanja postupka izgaranja: paljenje iskrom i ponovo, poslije isključenja, ubrizgavanje zapaljive doze. Cilj je istraživanja bilo utvrđivanje razlika u postupku izgaranja i radu motora, prije svega promjena tlaka do kojih je došlo u cilindru te vrste motora s dva sustava napajanja energijom. Zapaljiva doza uštrcana u cilindar bila je jednaka otprilike 5 ÷ 8 % ukupne mase goriva u motoru. Gorivo je direktno ubrizgavano tijekom nekoliko desetaka stupnjeva rotacije koljenaste osovine prije dostizanja gornje mrtve točke. Pripremljena je prostorna mreža modela motora (predprocesor), a napravljena je i modifikacija izvornog KIVA 3V programa kako bi se uzela u obzir dva sustava ubrizgavanja. Treba spomenuti da standardni KIVA 3V program ima, po defaultu, samo jedan izvor ubrizgavanja goriva.The article presents simulation researches on the combustion process in the four-cylinder testing engine, based on the spark ignition engine Toyota Yaris 1,3 dm3 which was equipped with two systems of power supply i.e.: fundamental and ignition. Two methods of initiating the combustion process were applied: by spark ignition and, after it was turned off, by means of the ignition dose injection. The researches aimed at revealing the differences in the combustion process and engine performance, above all the changes in pressure that occurred in the cylinder for that kind of two-fuel power supply of the engine. The ignition dose injected into the cylinder was equal to about 5 ÷ 8 % of the general mass of the fuel supplied to the engine. The mass of the fuel injected into the approach collector determined the remaining part, and the direct injection of the fuel took place over several dozen of rotation degrees of the crankshaft before TDC (Top Dead Centre). A spatial grid of the engine’s model (pre-processor) was prepared, and also a modification to the source KIVA 3V program was made consisting in taking into account of two systems of injection. It is necessary to mention that the standard KIVA 3V program contains, as a default, only one source of fuel injection

Spatial distribution of air temperature on Svalbard during 1 year with campaign measurements

In this article, the results of an investigation into the air temperature conditions on Svalbard in the period 1 September 2010 to 31 August 2011 are presented. For this period, parallel temperature measurements have been made as many as in 30 sites. On the basis of this unique set of data it was possible to study, in detail, the spatial distribution of different thermal characteristics [mean temperature, diurnal temperature range (DTR), day-to-day variability, degree of climate continentality, etc.] in Svalbard. Such knowledge of the whole of Svalbard was not previously available with sufficient accuracy for all areas. High resolution maps showing the spatial distribution of all studied thermal characteristics were also produced and analysed. Analysis of surface temperature data shows that the markedly coldest area throughout the whole year was northern Svalbard, and in particular its eastern side (Nordaustlandet). On the other hand, the highest temperatures were recorded in western part of Spitsbergen. The greatest spatial decreasing rate of temperature in Svalbard throughout the whole year was observed in a southwest (SW)–northeast (NE) direction. The distribution of mean seasonal and annual temperature reduced to sea level on Svalbard differs from the distribution based on surface temperatures. Spring, and in particular winter, saw the greatest DTRs (4–7 and 6–9 °C, respectively), while the lowest were observed in summer (3.0–3.5 °C). In all seasons, the highest DTR were mainly noted in the NE part of Svalbard, while the lowest were in its SW part. The lowest continentality of climate (30%) is clearly seen in the south-western part of Svalbard, while the highest values (above 43%) stretch from the western part of Nordaustlandet to the area of Sveagruva in the central-eastern part of Spitsbergen. The NORA10 hindcast temperature data differ significantly from measured data for some seasons and areas and need bias corrections when used in climatology

Opportunities for the Application of 3D Printing in the Critical Infrastructure System

The present article presents an analysis of the potential application of 3D printing in the critical infrastructure system. An attempt has been made to develop case studies for selected critical infrastructure areas, particularly with reference to the area of energy supply. The need for 3D printing applications is identified based on expert research in the energy industry. It identifies the application schemes determined by the technical and logistical possibilities associated with 3D printing in its broadest sense. A review of additive technologies with a view to their application in selected phases of critical infrastructure operation, including in crisis situations, is also carried out. Furthermore, a methodology for incorporating 3D printing into the existing critical infrastructure system is proposed. As a result, the following research hypothesis is adopted: the use of 3D printing can be an important part of measures to ensure the full functionality and efficiency of critical infrastructures, particularly in crisis situations

MODELLING AND TESTING OF DYNAMIC PROPERTIES OF C0-45 TURBOCHARGERS

The paper presents modelling process and results of the bench tests of the C0-45, which is a turbocharger for heavy-duty diesel engines. For turbochargers like this, it is necessary to measure the level of vibration. This paper presents the test results for 115 turbochargers. Rotor speed during the tests varied between 25,000 and 42,000 rpm. Rotor speed during the tests on a C0-45 turbocharger varied within three ranges, i.e., Range I: n=25,000-32,000 rpm and a=0.5g; Range II: n=33,000-38,000 rpm and a=1.0g; Range III: n=39,000-42,000 rpm and a=1.5g; (g=9.81m/s2). Measurement of vibrations was realized by a sensor located on the body of the turbocharger. Bench tests also included measurement of key charge parameters such as the amount of mass trapped, mean flow velocities, turbulence level, gas pressure, temperature and oil flow. The results are presented in the form of diagrams showing the amplitude of the acceleration function with regard to the rotor’s RPM. Research shows that using the correct parameters in construction and technological processes of assembly are very important for the effective functioning turbochargers