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Number of results: 13
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Abstract

This article presents a case study of a large wedge failure. It took place during excavation of the last bench of storage cavern with an approximate dimension of 80 m long having a depth of 8 m. The adopted intervention followed a structured approach, which included immediate rock support, geotechnical and geological investigations in the failure zone and design modifications. Back analyses of the failure zone were also carried out to assess design parameters with observed geological conditions. Re assessment in the failure zone was carried out using modified design parameters, which included shorter benches, rock support installation schemes such as longer rock bolts, reinforced ribs of shotcrete and reduced construction advances. Geotechnical monitoring in and around failure zone were carried out for recording any alarming movements in the rock mass. Initially, geotechnical monitoring was carried out in the recently excavated zone of the cavern on a daily basis. Based on continuous monitoring data for at least one week, the frequency of subsequent monitoring can be decided. In most cases the deformation of rock mass was considerably less than the alarming values which were calculated based on detailed design for different rock classes. The paper discusses the failure, investigation, cause, assessment and remedial measures to complete the construction of cavern.
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Abstract

Evolution of many high technologies such as microelectronics, microsystem technology and nanotechnology involves design, application and testing of technical structures, whose size is being decreased continuously. Scanning probe microscopes (SPM) are therefore increasingly used as diagnostic and measurement instruments. Consequently the demand for standardized calibration routines for this kind of equipment rises. Up to now, there has been no in generally accepted guideline on how to perform SPM calibration procedure. In this article we discuss calibration scheme and focus on several critical aspects of SPM characterization e.g. the determination of the static and dynamic physical properties of the cantilever, the influence factors which need to be considered when plotting a scheme for the calibration of the force and displacement sensitivity.
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Abstract

Measurements of the hardening process of the selected self-setting sands are presented in the hereby paper. Moulding sands were prepared on the matrix of „Szczakowa” sand of the Sibelco Company. Two resins: phenol-formaldehyde-furfuryl (FF/AF) and urea-formaldehydefurfuryl (MF/AF) were used for making moulding sands. – Methylbenzene-sulphonic acid was applied as a hardener for the moulding sand on FF/AF resin, while paratoluene-sulphonic acid for the moulding sand on MF/AF resin. Both hardeners were used in two concentrations: low – the so-called ‘slow’ hardener and high - ‘fast’ hardener. During investigations, the courses of the hardening process were determined, more accurately changes of the velocity of the ultrasound wave passage through the moulding sand cL = f(t) and changes of the moulding sand hardening degree versus time, Sx = f(t). In addition, the kinetics of the hardening process was determined. Measurements were performed on the research stand for ultrasound investigations.
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Abstract

Measurements of the hardening process course of the selected self-hardening moulding sands with the reclaimed material additions to the matrix, are presented in the hereby paper. Moulding sands were produced on the „Szczakowa” sand (of the Sibelco Company) as the matrix of the main fraction FG 0,40/0,32/0,20, while the reclaim was added to it in amounts of 20, 50 and 70%. Regeneration was performed with a horizontal mechanical regenerator capacity of 10 t/h. In addition, two moulding sands, one on the fresh sand matrix another on the reclaimed matrix, were prepared for comparison. Highly-fluid urea-furfuryl resin was used as a binder, while paratoluensulphonic acid as a hardener. During investigations the hardening process course was determined, it means the wave velocity change in time: cL = f(t). The hardening process kinetics was also assessed (dClx/dt = f(t)). Investigations were carried out on the research stand for ultrasound tests. In addition strength tests were performed.
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Abstract

The article presents research results of physico-chemical and environmental issues for the dust generated during dedusting of the installation for the processing and preparation of moulding sand with bentonite. Particular attention was paid to the content of heavy metals and emission of gases from the BTEX group, which is one of the determinants of the moulding sands harmfulness for the environment. The analysis of heavy metals in the test samples indicate that there is an increase of the content of all metals in the dust compared to the initial mixture of bentonite. The most significant (almost double) increase observed for zinc is probably related to the adsorption of this element on the dust surface by contact with the liquid metal. The study showed, that dust contained more than 20% of the amount of montmorillonite and had a loss on ignition at a similar level. The addition of 1% of dust to the used moulding sand results in almost 30% increase in the total volume of gases generated in casting processes and nearly 30% increase of the benzene emission.
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Abstract

The paper deals with experimental investigations of a set of metal "2-delta" gaskets of different depth. The gaskets were examined under assembly conditions, i.e. placed in their seats and loaded with the compressive assembly force with no operating pressure applied to the closure. The electric resistance wire strain gauges were used to measure the circumferential and axial strains at the inner cylindrical surface of the gaskets. The plastic deformations of the contact surface of the seats were measured after disassembly of the closures. The material tests were carried out to determine real mechanical properties of materials applied for the gaskets and the seats. The results of experiment were compared with the analytical approach. The plastic deformations were taken into account in the analytical solution of the contact region between the gasket and the seats. The results of experiment and analytical approach were verified by FEM calculations, which take into account linear hardening of the material, friction and contact effects.
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Abstract

This paper presents the summary of research activities carried out in Poland in 2011–2014 in the field of Earth rotation and geodynamics by several Polish research institutions. It contains a summary of works on Earth rotation, including evaluation and prediction of its parameters and analysis of the related excitation data as well as research on associated geodynamic phenomena such as geocentre motion, global sea level change and hydrological processes. The second part of the paper deals with monitoring of geodynamic phenomena. It contains analysis of geodynamic networks of local, and regional scale using space (GNSS and SLR) techniques, Earth tides monitoring with gravimeters and water-tube hydrostatic clinometer, and the determination of secular variation of the Earth’ magnetic field.
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Abstract

Theoretical problems concerning the determination of work parameters of the two-phase sand-air stream in the cores making process by blowing methods as well as experimental methods of determination of the main and auxiliary parameters of this process decisive on the cores quality assessed by the value and distribution of their apparent density are presented in the paper. In addition the results of visualisations of the core-box filling with the sand-air stream, from the blowing chamber, obtained by the process filming by means of the quick-action camera are presented in the paper and compared with the results of simulation calculations with the application of the ProCast software.
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Abstract

The effects of filling the core box cavity and sand compaction in processes of core production by blowing methods (blowing, shooting) depend on several main factors. The most important are: geometrical parameters of cavity and complexity of its shape, number, distribution and shape of blowing holes feeding sands as well as the venting of a technological cavity. Values of individual parameters are selected according to various criteria, but mostly they should be adjusted to properties of the applied core sand. Various methods developed by several researchers, including the authors own attempts, allow to assess core sands properties on the basis of special technological tests projecting the process into a laboratory scale. The developed criteria defining a degree or a filling ability factor provide a better possibility of assessing the core sand behavior during flowing and core box filling, which indicate the value and structure of the obtained compacting decisive – after hardening – for strength and permeability. The mentioned above aspects are analyzed – on the basis of authors’ own examinations - in the hereby paper.
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Abstract

Shape memory alloys are characterised by interesting properties, i.e. shape memory effect and pseudoelasticity, which enable their increasing application. Thermomechanical aspects of martensitic and reverse transformations in TiNi shape memory alloy subjected to tension tests were investigated. The stress-strain characteristics obtained during the tests were completed by the temperature characteristics. The temperature changes were calculated on the basis of thermograms determined by an infrared camera. Taking advantages from the infrared technique, the temperature distributions on the specimen’s surface were found. Heterogeneous temperature distributions, related to the nucleation and development of the new martensite phase, were registered and analysed. A significant temperature increase, up to 30 K, was registered during the martensitic transformation. The similar effects of the heterogeneous temperature distribution were observed during unloading, while the reverse transformation, martensite into austenite took place, accompanied by significant temperature decrease.
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Abstract

The paper presents an estimation of liquefaction susceptibility of some soils from the coast of the Marmara Sea, which was heavily striken by the Kocaeli earthquake in 1999. Firstly, the results of field investigations are summarized. Then, the results of laboratory investigations of physical and mechanical properties of the soils collated from the sites investigated are presented. The mechanical properties relate to the compaction/liquefaction model of saturated soils. This model is briefly outlined, then respective experimental procedures dealing with its calibration described, and values of material parameters listed. Liquefaction potential of investigated soils is analysed using standard procedures, based on the grain size distribution curves and SPTs. Finally, the simulation of pore-pressure generation and onset of liquefaction of Turkish soils is carried out, using the compaction/liquefaction model. Discussion of some standard empirical procedures of estimation of liquefaction potential of saturated soils, conducted from the analytical point of view, is also presented.
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Abstract

The article discusses the problem of province and smaller cities/towns within general political and social changes in critical times of Communists’ Poland and the role played by smaller communities in the occuring changes. The Author states that the influence range of central changes in the Communists’ party PZPR and other state organs in Warsow had a weaker feedback on the province and their regional pendants. The same concerned vivid social workers’ and independence movements, strikes and different struggles. The neighbourhood of two big centres: Szczecin and Gdańsk, the craddle of „Solidarność”, have had a rather low-rated effect on the changes in Koszalin (mainly influenced by Szczecin) and Słupsk (mainly influenced by Gdańsk) region. The both centres were active clusters of oppositional movements. Between them, as Marciniak stated, existed in the years 1956–1981 a precipice, a ‘sociological vacuum’, conditioned mainly by a lack of strong academic, intellectual and religious circles.
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Abstract

The paper deals with experimental investigations of a set of metal wave-ring gaskets of different thickness and different assembly interference. The gaskets were examined under assembly conditions, i.e. pressed in their seats with no operating pressure applied. The electric resistance wire strain gauges were used to measure the circumferential and axial strains at the inner surface of the gaskets. The traces of contact at the working surface of the gaskets were measured after disassembly the gaskets from their seats. The material tests were carried out to determine the real mechanical properties of materials applied for the gaskets and the seats. The results of experiment were verified by FEM calculations and compared with the analytical approach based on the simplified shell model proposed for the gasket.
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