The problem of influence of mechanical vibrations on a measurement is well known and analyzed for ground conditions. However, the problem becomes quite essential and difficult to solve in space conditions. The influence of vibrations on accuracy of the measurement was observed on MIPAS – ENVISAT and in PFS Mars Express.
This paper presents an experimental and theoretical investigation on sensitivity to mechanical disturbances of the Fourier-transform infrared spectrometer PFS.
A theoretical analysis has been performed in order to highlight the expected effect of the vibration, then laboratory tests have been designed and carried out for instrument characterization.
The theoretical investigation has been confirmed by experimental tests.
The data were distorted by errors that reflect the influence of vibrations on the instrument and temperature instability of the reference source.
The considerations are a perfect example presenting the scale of vibrations problem and the instability of the reference source in assessing accuracy of the measurement in space.
The results presented in this article are part of the research on fatigue life of various foundry alloys carried out in recent years in the Lukasiewicz Research Network – Institute of Precision Mechanics and AGH University of Science and Technology, Faculty of Foundry Engineering. The article discusses the test results obtained for the EN-GJS-600-3 cast iron in an original modified low-cycle fatigue test (MLCF), which seems to be a beneficial research tool allowing its users to evaluate the mechanical properties of materials with microstructural heterogeneities under both static and dynamic loads. For a comprehensive analysis of the mechanical behaviour with a focus on fatigue life of alloys, an original modified low cycle fatigue method (MLCF) adapted to the actually available test machine was used. The results of metallographic examinations carried out by light microscopy were also presented. From the analysis of the results of the conducted mechanical tests and structural examinations it follows that the MLCF method is fully applicable in a quick and economically justified assessment of the quality of ductile iron after normalizing treatment.
This paper presents the results of research regarding measurements of the values of pressure drops during horizontal flow of gas-liquid and gas-liquid-liquid mixture through 180o pipe bends. The conducted insightful analysis and assessment during multi-phase flow in pipe bends has enabled to develop a new method for determination of their values. This new method for determining pressure drops ensures higher precision of calculation in comparison to other methods presented in literature and can be applied for calculation of these parameters during multi-phase flows in pipe bends with various geometries.
The paper presents the results of comparative tests of the fatigue properties conducted on two non-ferrous alloys designated as Al 6082 and
Al 7075 which, due to the satisfactory functional characteristics, are widely used as engineering materials. The fatigue tests were carried
out using a proprietary, modified low cycle test (MLCF). Particular attention was paid to the fatigue strength exponent b and fatigue
ductility exponent c. Based on the tests carried out, the results comprised within the range defined by the literature were obtained. These
results prove a satisfactory sensitivity of the method applied, its efficiency, the possibility of conducting tests in a fully economical way
and above all the reliability of the obtained results of the measurements. Thus, the thesis has been justified that the modified low cycle
fatigue test (MLCF) can be recommended as a tool used in the development of alloy characteristics within the range of low-cycle variable
loads
This study discloses the characteristic features of the modified low-cycle fatigue test used for the determination of the mechanical
properties of two types of cast iron, i.e. EN-GJL-250 and EN-GJS-600-3. For selected materials, metallographic studies were also
conducted in the range of light microscopy and scanning microscopy.
The purpose of the article is to systematize the main issues related to the encounter of Christianity with Latin American cultures. The study is based on both Latin American theological publications and various documents of the Roman Catholic Church. In the first part the problem of Christianity’s encounter with cultures of this region from historic perspective is discussed by pointing out to its negative, ambiguous and positive aspects. The second part is devoted to classification of culture circles, significant from the point of view of evangelization and inculturation (cultures of urban agglomeration, rural regions, Indian and Afro-Latin American cultures, poverty, elites, cyber culture and popular culture). In the final section we paid attention to the issue of up-coming culture and its trends (modernism and postmodernism, secularism, socio-political ideologies, the role of mass media, the tensions between globalization process and appreciation of local traditions).
This paper presents results of numerical investigation on a controllable airfoil flow separation phenomena practically applied in Formula One racing by a device called the F-duct. Separation is forced by air jets from slots located at different positions on the profile of the dual element wing and is intended to reduce aerodynamic drag. Slot position and the air jet velocity are the main parameters controlling the flow separation. The flow structure, surface pressure distribution, and the generated downwards lift and drag forces were investigated in this study. Two different flow separation structures have been recognised. Typically, wing stall is correlated with an increase in aerodynamic drag force. However, in the case of the finite wing with low aspect ratio, the induced drag is dominant and is proportional to the downforce. Therefore, flow separation on the wing increases the profile drag while simultaneously reducing the induced drag, resulting in a decrease in the total aerodynamic drag.