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Number of results: 9
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Abstract

Field investigations concerning screw piles and columns have been carried out for the “Bearing capacity and work in the soil of screw piles” research project, financed by the Polish Ministry of Science and Higher Education – project No N N506 369234. The tests of three instrumented screw piles were conducted together with CPTU tests and measurements of pile installation parameters (especially torque). The objectives of field investigations and the entire research project include discovering how screw piles work in the soil, locating and describing the correlations between CPTU results and rotation resistance during pile auger installation and next establishing correlations between CPTU results, rotation resistance and the bearing capacity of this kind of piles. The paper describes the investigation procedure and the basic results of tests carried out in the first of a series of sites.

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Authors and Affiliations

A. Krasiński
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Abstract

Deep excavation walls can be analyzed and calculated by using classical methods (currently rarely in use due to their many simplifications) or numerical methods. Among the numerical methods we can distinguish a simplified approach, in which the interaction between soil and a wall structure is modelled by a system of elasto-plastic supports, and the finite-element method (FEM) in which the soil is modelled with mesh of elements. It is a common view that if we want to analyze only wall constructions, the first, simplified method of calculation is sufficient. The second method, FEM, is required if we want to further analyze the stress and strain states in the soil and the influence of the excavation on the surrounding area. However, as it is demonstrated in the paper, important differences may appear in the calculation results of both methods. Thus, the safety design of a deep excavation structure depends very much on the choice of calculating method.

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Authors and Affiliations

A. Krasiński
M. Urban
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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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Authors and Affiliations

Maciej Krasiński
Andrzej Trojnacki
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Abstract

The paper presents a research work on the process of emulsion separation by filtration-coalescence method in the presence of solid particles. A polyester PBT coalescence medium was used in experiments of water removal from diesel fuel. Apart from parameters representing the geometry and inherent properties of coalescence filters, the additional emulsion constituents such as surfactants and solid particles also affect the process. These constituent can cover fibres and they can also influence emulsion properties. It has been experimentally confirmed that contrary to surface active compounds, which stabilise the emulsion, the presence of specific solid particles decreased the system stability. If surface active compounds are present in the system, the influence of solid particles is different at the same concentration level depending on their type. The destabilization of emulsion due to the presence of Arizona dust was more pronounced. Although the presence of particles mitigated the effect of surfactants, their deposition in the filter media oppositely affected the coalescence process depending on solid type. Oleophilic iron oxide particles improved the separation efficiency of water from diesel fuel, while Arizona test dust had a negative impact on the separation process performance.
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Authors and Affiliations

Andrzej Krasiński
1
Łukasz Sołtan
1
Jakub Kozyrski
1

  1. Warsaw University of Technology, Faculty of Chemical and Process Engineering, Warynskiego 1, 00-645 Warsaw, Poland
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Abstract

In this study, the process of membrane cleaning by supercritical fluid extraction was investigated. Polypropylene microfiltration membranes, contaminated with oils, were treated in a batch process with a supercritical fluid (SCF). As extractant, pure supercritical carbon dioxide or supercritical carbon dioxide with admixtures of methanol, ethanol and isopropanol were used. Single-stage and multi-stage extraction was carried out and process efficiency was determined. The obtained results showed that addition of organic solvents significantly enhances the cleaning performance, which increases with increase of organic solvent concentration and decreases with increasing temperature. All three solvents showed a comparable effect of efficiency enhancement. The results confirmed that supercritical fluid extraction can be applied for polypropylene membrane cleaning.

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Authors and Affiliations

Jan Krzysztoforski
Andrzej Krasiński
Marek Henczka
Wojciech Piątkiewicz
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Abstract

In this work the esterification of diethyl tartrate was studied. The research was focused on the enhancement of reversible reaction yield, which is accomplished by dewatering of the reaction mixture. The removal of water shifts the equilibrium towards the main product. Pervaporation was applied for this purpose, and results were compared to distillation. The advantages and limitations of both processes are discussed. The experimental part consists of dewatering of mixture after the reaction had reached the equilibrium, and was subsequently fed to the test rig equipped with a single zeolite membrane purchased from Pervatech B.V. Results show a significant conversion increase as a result of water removal by pervaporation. Compared to distillation no addition of organics is necessary to efficiently remove water above the azeotrope. Nevertheless, some limitations and issues which call for optimisation are pointed out. A simple numerical model is proposed to support design and sizing of the pervaporation system. Various modes of integrated system operation are also briefly discussed.

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Authors and Affiliations

Andrzej Krasiński
Patrycja Wierzba
Agata Grudzień
Halina Hajmowicz
Krzysztof Zawada
Ludwik Synoradzki
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Abstract

The aim of this article is to present the ephemera related to Sandomierz — either by content or place of the publication — whose distinctive trait was the use of the word 'jednodniówka', or single issue, in the title, the subtitle or the contents. Chronologically, this survey ranges from 1918, the date of the first print of this kind to be published, to the last one (known to the au-thors) dated 2002 and does not cover publications in languages other than Polish. The source material gathered in accordance with these criteria comprises a total of 34 single issues, of which ten appeared in the pre-war period and twenty-four after World War II. Themati-cally, ten of them can be classified as political or concerned with social issues; eight are products of trade unions or other professional associations; twelve are aimed at the younger generation; and each of the remaining four has a focus of its own (i.e. military, historical, religious, literary-artistic). In this article all of the single issues are discussed both with regard to their in format (layout) and their content.
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Authors and Affiliations

Izabela Krasiński
1
ORCID: ORCID
Piotr Sławiński
2
ORCID: ORCID

  1. Katedra Dziennikarstwa i Komunikacji Społecznej, Uniwersytet Jana Kochanowskiego, ul. Uniwersytecka 17, PL 25-406 Kielce
  2. Archiwum Państwowe w Kielcach, Oddział w Sandomierzu, ul. Żydowska 4, PL 27-600 Sandomierz
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Abstract

Predicting the Q–s settlement characteristics of piles is an important element in the designing of pile foundations. The most reliable method in evaluating pile-soil interaction is the static load test, preferably performed with instrumentation for measuring shaft and pile base resistances. This, however, is a mostly post-implementation test. In the design phase, prediction methods are needed, in which numerical simulations play an increasingly popular role. This article proposes a procedure for numerically modeling the interaction of screw displacement piles with soil using the ZSoil 2D FEM program. The procedure takes into account technological characteristics of this type of pile, such as the process of soil expansion during the screwing-in of the auger and the pressure of concrete mix after pile concreting. They significantly affect the soil stress state, which is a key parameter for the pile load capacity. Geotechnical parameters of the subsoil were adopted from CPTU probing and laboratory tests. Due to the physical complexity, a constitutive soil model “Hardening Soil” (HS) was used in the analyses. The modeling procedure was calibrated on the basis of the static load test results of several instrumented piles, which were carried out as part of the “DPDT-Auger” research project. As a result of these calibrations, generalized recommendations were derived for an entire single pile modeling process with the axisymmetric system of ZSoil program. These can be useful in the reliable FEM prediction of the Q–s characteristics for screw displacement piles for practical engineering purposes.
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Authors and Affiliations

Paweł Wiecławski
1
ORCID: ORCID
Adam Krasinski
1
ORCID: ORCID

  1. Gdansk University of Technology, Faculty of Civil and Environmental Engineering, ul. Narutowicza 11/12, 80-233 Gdansk Wrzeszcz, Poland

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