Show publications from the year
-
Show all publications from the year 2025
-
Show all publications from the year 2024
-
Show all publications from the year 2023
-
Show all publications from the year 2022
-
Show all publications from the year 2021
-
Show all publications from the year 2020
-
Show all publications from the year 2019
-
Show all publications from the year 2018
-
Show all publications from the year 2017
-
Show all publications from the year 2016
-
Show all publications from the year 2015
-
Show all publications from the year 2014
-
Show all publications from the year 2013
-
Show all publications from the year 2012
-
Show all publications from the year 2011
-
Show all publications from the year 2010
-
Show all publications from the year 2009
-
Show all publications from the year 2008
-
Show all publications from the year 2007
-
Show all publications from the year 2006
-
Show all publications from the year 2005
-
Show all publications from the year 2004
-
Show all publications from the year 2003
-
Show all publications from the year 2002
-
Show all publications from the year 2001
-
Show all publications from the year 2000
-
Show all publications from the year 1999
-
Show all publications from the year 1998
-
Show all publications from the year 1988
-
Show all publications from the year 1987
-
Show all publications from the year 1980
Publications from the year 2017
Show all-
PREDICTING CORPORATE BANKRUPTCIES IN POLAND AND LITHUANIA – COMPARATIVE ANALYSIS
- Błażej Prusak
The research on predicting bankruptcies of enterprises constitutes one of the most important areas of financial management. In developed countries, the first publications on the subject appeared in the early 20th century. The situation is different in the countries of Eastern Europe, which introduced the market system already at the beginning of the 1990s, which resulted in first corporate bankruptcies. The article compares experiences in the field of forecasting corporate bankruptcies in two countries of Eastern Europe, i.e. Poland and Lithuania, comparing them with the results of research conducted in developed countries. In conclusion, the similarities and differences between the two countries are identified and the future directions of research on this issue are proposed.
-
Prediction of manoeuvring abilities of 10000 DWT pod-driven coastal tanker
- Maciej Reichel
This paper aims to present a new approach in the prediction of manoeuvring abilities of pod-driven ships. A new mathematical model of motions based on MMG methodology was developed and a new type of description of forces acting on azimuth drives is presented. Captive model tests of medium-size coastal tanker and pod open water tests were carried out in CTO S.A. (Ship Design and Research Centre S.A.) to obtain hull hydrodynamic derivatives and pod propulsor hydrodynamic coefficients. Fast-time simulations were carried out and results were compared with free running model tests. Validation shows acceptable agreement between numerical and experimental results, i.e. confirms the usability of developed mathematical model to identify the trends in performance also for course unstable ship.
-
Prediction of Ship Resonant Rolling - Related Dangerous Zones with Regard to the Equivalent Metacentric Height Governing Natural Frequency of Roll
- Przemysław Krata
- Wojciech Wawrzyński
Potentially dangerous zones corresponding to dynamical stability phenomena, possibly encountered by ships sailing in rough sea, are estimated nowadays with the use of the method recommended by IMO in the guidance coded MSC.1/Circ.1228. In this IMO method the parameter governing the natural period of roll is the initial metacentric height. Some earlier studies revealed that the initial metacentric height which is commonly in use on‐board ships for the purpose of performing the MSC.1/Circ.1228‐recommended calculations, may significantly vary from the so called equivalent metacentric height obtained for large amplitudes of ship’s roll. In the light of such ascertainment, the paper deals with resultant resonance roll zones locations with regard to the equivalent metacentric height concept remaining appropriate for large amplitudes of roll. The noteworthy transfer of the resonance zones location is disclosed which reflects the distinct configurations of potentially dangerous ship’s course and speed configurations than could be predicted on the basis the initial metacentric height.
-
Prediction of the Mechanical Properties of P91 Steel by Means of Magneto-acoustic Emission and Acoustic Birefringence
- Katarzyna Makowska
- Leszek Piotrowski
- Zbigniew Kowalewski
The paper describes an application of nondestructive volumetric magnetic and ultrasonic techniques for evaluation of the selected mechanical parameter variations of P91 steel having direct influence on its suitability for further use in critical components used in power plants. Two different types of deformation processes were carried out. First, a series of the P91 steel specimens was subjected to creep and second, one to plastic deformation in order to achieve the material with an increasing strain level up to 10%. Subsequently, non-destructive and destructive tests were performed. Magnetic methods based on measurements of magnetoacoustic emission and magnetic hysteresis loop changes as well as the ultrasonic method based on acoustic birefringence measurements, were applied. Finally, the static tensile tests were carried out in order to evaluate the mechanical parameters. It is shown that some relationships between the selected parameters coming from the non-destructive and destructive tests may be formulated.
-
Preliminary design of the last stage of supercritical steam turbine and proposition of anti-erosion coating for blades surface
- Anna Milewska
- Stanisław Głuch
- Anna Zykova
- Safonov Vladimir
In this article a preliminary design of the last stage of supercritical steam turbine has been presented. A computational model of supercritical thermal cycle has been created in order to determine steam parameters at the stage inlet and outlet. The model was based on the structure of German coal-fired power plant Datteln 4. Further steam-flow parame-ters and dimensions of stator and rotor blades have been calculated analytically. Stage geometry has been created and steam flow through designed stage upper-part has been simulated. Operating conditions of steam turbine last stages have been discussed and protective anti-erosion coating of blades surfaces has been proposed.
-
PRELIMINARY FIELD TESTS AND LONG-TERM MONITORING AS A METHOD OF DESIGN RISK MITIGATION: A CASE STUDY OF GDAŃSK DEEPWATER CONTAINER TERMINAL
- Mikołaj Miśkiewicz
- Oskar Mitrosz
- Tadeusz Brzozowski
Appropriate risk assessment plays a fundamental role in the design. . The authors propose a possible method of design risk mitigation, which follows recommendations included in Eurocode 7. The so-called “Observational Method” (OM) can produce savings in costs and programmes on engineering projects without compromising safety. The case study presented is a complex design solution that deals with the heavy foundations of a gantry crane beam as one of the elements of a Deepwater Container Terminal extension. The paper presents a detailed process of the design of the rear crane beam being a part of the brand new berth, together with its static analysis, as well as the long-term results of observations, which have revealed the real performance of the marine structure. The case presented is based on excessive preliminary field tests and technical monitoring of the structure, and is an example of a successful OM implementation and design risk mitigation.
-
PRELIMINARY RESULTS FROM APPLICATION PHOSLOCK® TO REMOVE PHOSPHORUS COMPOUNDS FROM WASTEWATER
- Magdalena Gajewska
- Magda Kasprzyk
The aim of the study is to assess the removal effectiveness of phosphorus compoundsby using lanthanum-modified bentonite. This material was produced by the Australian company Phoslock® Water Solutions Pty Ltd. According to the company, Phoslock® has substantial capacity to bound phosphate anions. The investigation was carried out in steady conditions in laboratory model with beakers. The results of the study are related to the determination of hydraulic load, time of mixing and time of sedimentation. Research with synthetic wastewater was conducted in 4 beakers which were mixing by 5, 10, 20 and 30 minutes respectively. Samples for analyzing were taken from each beaker after 30 minutes, 1, 2, 3, 4 and 24 hours of sedimentation. Studies were conducted to determine the optimal dose of Phoslock® with a known concentration of phosphate anions PO4 3- in artificial wastewater, time of mixing and time of sedimentation. All samples were taken before and after the treatment with Phoslock® and they were analyzed with following parameters: pH, total suspended solids, conductivity, turbidity, color and phosphate concentration. The carried out investigations confirmed high efficiency of phosphate anions PO43- removal (over 95%), and the final concentration as average was 0.1 mg/dm3. The application of Phoslock® for phosphate anions PO4 3- did not change the pH of final effluent.
-
Preliminary Results from the Removal of Phosphorus Compounds with Selected Sorption Material
- Magda Kasprzyk
- Ewa Wojciechowska
- Hanna Obarska-Pempkowiak
- Marta Thomas
Due to the resources of phosphorous are limited and are exhausted in the next 30 years the management of the resources is become current issue. Most of the phosphorus compounds is lost forever, because it is discharged with sewage into surface waters, causing eutrophication and in this way causing a further problem and challenge. On the other hand, there is a considerable need for phosphorus compounds, primarily in bioavailable forms. The aim of the study is to compare the capacity to retain phosphorus compounds on different sorption materials. During the experiments both synthetic and real wastewater are used. The synthetic wastewater simulates the composition of the reject water (RW) generated during the mechanical dewatering of the digested sewage sludge, and the real RW comes from WWTP in Gdansk. The research is carried out within the subtask 2.3 of the project entitled “Integrated technology for improved energy balance and reduced greenhouse gas emissions at municipal wastewater treatment plants” with the acronym “BARITECH” co-funded by the Norwegian funds, under the Polish-Norwegian Cooperation Research carried out by the National Centre for Research and Development (197025/37/2013). For the investigation in dynamic conditions (flow through the column) four kinds of material have been selected. One of the column constituting control filled with washed gravel (2-8 mm). Other columns filled with natural material: (i) calcium – silica rock subjected to heat treatment, and waste materials, from water purification plan- the substrate form the filter for iron and manganese removal: (ii) from the first stage of iron removal (Fe), and (iii) the second stage of manganese removal (Mn). Substrate (ii and iii) are covered by iron oxide or manganese oxide respectively and both of them are proven to be good in bounding of P-compounds. In steady conditions the investigation were carried out with Phoslock which is chemically lanthanum clay. The result of investigation are related to the determination of the sorption capacity with respect to the analysed content of phosphorus compounds in dynamic conditions of flow and for stable conditions the determination of hydraulic load and way and time of mixing. For the synthetic wastewater the removal efficiency of phosphorous was 99.8% while for reject water (RW) generated during the mechanical dewatering of the digested sewage sludge was lower and equal to 85%.
-
Preparation and photocatalytic activity of Nd-modified TiO2 photocatalysts: Insight into the excitation mechanism under visible light
- Patrycja Parnicka
- Paweł Mazierski
- Tomasz Grzyb
- Zhishun Wei
- Ewa Kowalska
- Bunsho Ohtani
- Wojciech Lisowski
- Tomasz Klimczuk
- Joanna Nadolna
Titanium dioxide (TiO2) nanoparticles (NPs) modified with neodymium (Nd) in the range between 0.1 and 1.0 mol% were prepared via the hydrothermal method. The samples obtained were characterized by diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), X-ray fluorescence (EDX), Brunauer–Emmett–Teller (BET) method, X-ray powder diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS) and photoluminescence spectroscopy (PL). The photocatalytic activity of the obtained samples was evaluated by photodegradation of phenol in aqueous solution under ultraviolet– visible (UV–Vis, k > 350 nm) and visible (Vis, k > 420 nm) irradiation. Experimental results showed that the photocatalysts exhibited high photocatalytic activity under Vis light. The sample showing the highest photoactivity under Vis irradiation was in the form of anatase; its surface area equalled 124 m2/g (1.16 times larger than that of pristine TiO2). The average crystal size was 10.9 nm, and it was modified with 0.1 mol% of Nd3+ (28% of phenol was degraded after 60 min of irradiation). The photocatalytic tests of phenol degradation in the presence of scavengers confirm that e and were responsible for the visible light degradation of organic compounds in the aqueous phase. Action spectra analysis revealed that although Nd-modified TiO2 could be excited under visible light in the range of 400– 480 nm, the up-conversion process is not responsible for the degradation of phenol under Vis irradiation.
-
Preparation and photocatalytic properties of BaZrO 3 and SrZrO 3 modified with Cu 2 O/Bi 2 O 3 quantum dots
- Magdalena Miodyńska
- Beata Bajorowicz
- Paweł Mazierski
- Wojciech Lisowski
- Tomasz Klimczuk
- Michał Jerzy Winiarski
- Adriana Zaleska-Medynska
- Joanna Nadolna
In this study, we report a novel method of BaZrO3 and SrZrO3 surface modification by two different types of quantum dots (QDs, Cu2O and Bi2O3), which improved the photocatalytic performance of the obtained materials under UV-Vis light irradiation. Pristine BaZrO3 and SrZrO3 were prepared by the hydrothermal method. The deposition of Cu2O- and Bi2O3-QDs was carried out by chemical reduction. The morphology of the nanoparticles was estimated based on microscopic analysis (SEM, TEM). The perovskite structure and phase composition of polycrystals were confirmed by X-ray powder diffraction analysis (XRD). The elemental surface composition and the chemical character of detected elements were identified by X-ray photoelectron spectroscopy (XPS). The absorption ability and luminescence properties of nanocomposites were investigated by UV–Vis diffuse-reflectance spectroscopy (DRS UV-Vis) and luminescence spectroscopy. The influence of Cu2O/Bi2O3-QDs modification on the photocatalytic activity of BaZrO3 and SrZrO3 was evaluated by the phenol photodegradation process in the liquid phase under UV-Vis and toluene degradation in the gas phase under Vis irradiation. The highest photoactivity under UV-Vis light was observed for BaZrO3/1% Cu2O/33% Bi2O3 and SrZrO3/1% Cu2O/33% Bi2O3 samples. Research also demonstrated that single-type QD deposition (Cu2O or Bi2O3) on the zirconate surface decreases the photoactivity in comparison with pristine zirconates. The mechanism of photocatalytic activity of the obtained nanocomposites was investigated by the formation of hydroxyl radicals under UV-Vis irradiation in the presence of terephthalic acid.
-
Preparation, characterization and anti-colitis activity of curcumin-asafoetida complex encapsulated in turmeric nanofiber
- Sreeraj Gopi
- Augustine Amalraj
- Shintu Jude
- Karthik Varma
- T.r. Sreeraj
- Józef Haponiuk
- Sabu Thomas
Ulcerative colitis (UC) is a main form of inflammatory bowel disease (IBD). Asafoetida (ASF) and turmeric have traditionally been used for the treatment of various inflammatory diseases, including UC, because ASF is rich in sulfur compounds and turmeric contains curcumin (CUR). Turmeric nanofiber (TNF), the modified cell wall component of turmeric is considered to play important role in the human diet, health and can be used as a carrier agent to encapsulate bioactive components. A novel gut health product (GHP) was formulated by encapsulation of ASF and CUR complex onto TNF. The GHP was characterized by UPLC, GC-MS, FTIR, XRD, SEM with EDS and DSC studies. GHP was evaluated for anti-colitis activity in a rat model of 5% dextran sulfate sodium (DSS) induced UC. Treatment with GHP significantly attenuated the disease activity index, colitis score, histopathological changes and myeloperoxidase activity. GHP has significant protective effects against DSS induced colitis.
-
Preparation, morphology and properties of natural rubber composites filled with untreated short jute fibres
- Janusz Datta
- Marcin Włoch
Green composites were obtained by incorporation of short jute fibres in natural rubber matrix using a laboratory two-roll mill. The influence of untreated fibre content (1, 2.5, 5, 7.5 and 10 phr) on the mechanical properties, dynamic mechanical properties, swelling properties was examined. The behaviour of prepared green composites under cyclic compression was also investigated. Fibre dispersion in rubber matrix was studied by scanning electron microscopy. The highest tensile strength (21.1 MPa) and highest tear strength (39.9 N/mm) were found for composites containing 2.5 and 5 phr of short jute fibres, respectively. The results also suggested that increasing fibrous filler content resulted in increasing of tensile moduli 100, 200 and 300 % of elongation and hardness, and decreasing of rebound resilience and abrasion resistance of prepared jute/natural rubber composites. The cyclic compression test showed that increasing the amount of short jute fibres in the rubber matrix is related to increase of the energy dissipated in the composite. The incorporation of short jute fibres into the rubber matrix improves the stiffness of the composites, and it is related to the interaction between fibre surface and rubber matrix. The application of short fibres in higher amounts leads to formation of fibre agglomerates reducing the mobility of the rubber polymer chains. The mentioned agglomerates act as defects in rubber matrix, which caused decreasing of some properties, e.g. relative elongation at break.
-
Preventing of earthquake-induced pounding between steel structures by using polymer elements – experimental study
- Barbara Sołtysik
- Tomasz Falborski
- Robert Jankowski
Pounding between two, or more, adjacent buildings during earthquakes has been identified as one of the reasons for substantial damage or even total collapse of colliding structures, so it has been the subject of numerous studies in the recent years. A major reason leading to interactions between adjacent, insufficiently separated structures results from the differences in their dynamic properties. A number of different methods have been considered to mitigate earthquake-induced structural pounding. One of the techniques is linking structures which allow the forces to be transmitted between buildings and thus eliminate interactions. The aim of the present paper is to show the results of the experimental study focused on the application of polymer elements placed between the colliding members so as to mitigate earthquake-induced pounding between adjacent steel structures in series. In the study, three steel model towers with different dynamic parameters and various in-between distances were considered. The unidirectional shaking table was used in the experimental study. Models of steel towers were prepared and mounted to the platform of the shaking table. Additional mass was added at the top of each tower so as to obtain different dynamic characteristics of the structures. The results of the study indicate that earthquake-induced pounding may have a significant influence of the structural response. Moreover, the application of polymer elements between the structures can be an effective pounding mitigation technique. It allows us to prevent damaging collisions between adjacent structures during earthquakes. It also improves the structural behaviour leading to the reduction in vibrations under different seismic excitations.
-
Prevention of resonance oscillations in gear mechanisms using non-circular gears
- Oleksii Karpov
- Pavlo Nosko
- Pavlo Fil
- Oleksii Nosko
- Ulf Olofsson
One of the main disadvantages of gear mechanisms is the occurrence of noise and vibrations. This study investigated the applicability of non-circular gears for preventing resonance oscillations in gear mechanisms. The influence of a small deviation of the gear centrodes from the nominal circles on kinematic and oscillatory characteristics was analysed. It was shown that a larger deviation results in a smaller resonance amplitude due to mesh frequency variability and simultaneously in higher additional dynamic loads on the mechanism. The shape of the gear centrodes was determined which provides a relatively small resonance amplitude with minimum additional dynamic loads. A mechanical device was developed to enable cutting of slightly non-circular gears on a hobbing machine without numerical control.
-
-
Primary degradation of antidiabetic drugs
- Marta Markiewicz
- Christian Jungnickel
- Stefan Stolte
- Anna Białk-Bielińska
- Jolanta Kumirska
- Wojciech Mrozik
Type 2 diabetes is a chronic disease affecting a large portion of the world population and is treated by orally administered drugs. Since these drugs are often taken in high doses and are excreted unchanged or partially metabolised many of them are nowadays detected in surface waters or wastewater treatment plants effluents. Unmetabolised antidiabetics or some of their transformation products retain their pharmacological activity, therefore their presence in the environment is highly undesired. One of the main routes of elimination from wastewaters or surface waters is biodegradation. Within this work we tested primary biodegradation of: metformin and its metabolite guanylurea, acarbose, glibenclamide, gliclazide and glimepiride. We also inspected what might be the extent of the degradation by examining the products formed during the degradation using liquid chromatography coupled to tandem mass spectrometry. Transformation of diabetes staple drug metformin to dead-end product guanylurea was generally confirmed. An alternative, though rather minor pathway leading to complete mineralisation was also found. Complete primary degradation was observed for acarbose, glibenclamide and glimepiride whereas gliclazide was shown to be resistant to biodegradation. These results allow a preliminary assessment of environmental persistency of a very important group of pharmaceuticals and show need for implementing monitoring programs.
-
Probe signal processing for channel estimation in underwater acoustic communication system
- Iwona Kochańska
- Jan Schmidt
Underwater acoustic communication channels are characterized by a large variety of propagation conditions. Designing a reliable communication system requires knowledge of the transmission parameters of the channel, namely multipath delay spread, Doppler spread, coherence time, and coherence bandwidth. However, the possibilities of its estimation in a realtime underwater communication system are limited, mainly due to the computational time of implementations of the digital signal processing algorithms. The article presents the results of analysis of probe signals measured during a shallow water experiment. The implementation issues of estimation algorithms are discussed, assuming floating point arithmetic, and with both single-core and multi-core digital signal processors as the target platforms.
-
Problem powodzi miejskich
- Ziemowit Suligowski
Zagadnienia związane z powtarzającym się w Polsce zjawiskiem powodzi miejskiej pochodzącej od opadu. Problemy ocen ilościowych. Zagadnienie nadmiernego wpływu przeszłości na podejmowane działania, w efekcie niewłaściwa identyfikacja problemów. Przykład działań podjętych w Gdańsku. Inicjatywa bydgoska.