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Publikacje z roku 2018

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  • Pressure drop related to flow maldistribution in a model minichannel plate heat exchanger
    • Michał Klugmann
    • Paweł Dąbrowski
    • Dariusz Mikielewicz
    2018 Pełny tekst Archives of Thermodynamics

    The paper describes the issues related to the pressure drop that accompanies the phenomenon of maldistribution of working fluid between the channels of a model minichannel plate heat exchanger. The research concerns a single exchanger's plate containing 51 (in every geometry) parallel rectangular minichannels of hydraulic diameters 461 µm, 571 µm, 750 µm and 823 µm. In addition, the more complex geometry has been investigated, equipped with additional diagonal channels (so called extended geometry). The moment of the liquid phase transition through the heat exchanger was recorded at the flow rates from 0.83 g/s to 13.33 g/s in the inlet manifold. The article discusses the total pressure drop as a function of the flow rate and the characteristic dimension of minichannels, as well as the pressure drop as a function of the time of the fluid passage through the main part of the measuring section in which measurements were done. The resulting profiles correlate with the images of the flow distribution between channels recorded using the fast shutter speed camera, that allows to draw a further conclusions about the specifics of the maldistribution process. The impact of the total pressure drop on the actual range of optimum operating conditions of the heat exchanger was analyzed.

  • Pre-swirl energy saving device in marine application
    • Przemysław Król
    • Krzysztof Tesch
    2018 Pełny tekst Journal of Physics : Conference Series

    This paper covers topics of energy saving device (ESD) with application to marine propulsors. The form of ESD, considered in this paper, consists of fixed lifting foils mounted in front of the screw propeller (the pre-swirl stator/guide vanes). An algorithm for designing propulsion systems, consisting of guide vanes and screw propeller, is presented. The proposed method relies on hybrid lifting line (guide vanes)-lifting surface (screw propeller) vortex model. Additionally, an analysis method for such systems is also presented. It utilises lifting surface model for guide vanes as well as for screw propeller blades. Accuracy of the proposed method is notably lower in comparison with CFD calculations, however, the former is substantially faster and at the same time capable of providing accuracy sufficient for practical application. Further, the entire process of design and analysis is presented on the example of Nawigator XXI ship. The designed propulsion system, consisting of propeller CP753 and pre-swirl stator ST002, was manufactured and tested in model scale. Model tests revealed increased efficiency by 4% in the design point in comparison with with the Nawigator’s original propeller CP469. Finaly, model scale experimental results, conducted in Ship Hydrodynamics Division of CTO Gdansk, are compared with numerical predictions.

  • Pretreatment of Lignocellulosic Materials as Substrates for Fermentation Processes
    • Karolina Kucharska
    • Piotr Rybarczyk
    • Iwona Hołowacz
    • Rafał Łukajtis
    • Marta Glinka
    • Marian Antoni Kamiński
    2018 Pełny tekst MOLECULES

    Lignocellulosic biomass is an abundant and renewable resource that potentially contains large amounts of energy. It is an interesting alternative for fossil fuels, allowing the production of biofuels and other organic compounds. In this paper, a review devoted to the processing of lignocellulosic materials as substrates for fermentation processes is presented. The review focuses on physical, chemical, physicochemical, enzymatic, and microbiologic methods of biomass pretreatment. In addition to the evaluation of the mentioned methods, the aim of the paper is to understand the possibilities of the biomass pretreatment and their influence on the efficiency of biofuels and organic compounds production. The effects of different pretreatment methods on the lignocellulosic biomass structure are described along with a discussion of the benefits and drawbacks of each method, including the potential generation of inhibitory compounds for enzymatic hydrolysis, the effect on cellulose digestibility, the generation of compounds that are toxic for the environment, and energy and economic demand. The results of the investigations imply that only the stepwise pretreatment procedure may ensure effective fermentation of the lignocellulosic biomass. Pretreatment step is still a challenge for obtaining cost-effective and competitive technology for large-scale conversion of lignocellulosic biomass into fermentable sugars with low inhibitory concentration.

  • Prevalence Problem in the Set of Quadratic Stochastic Operators Acting on L1
    • Krzysztof Bartoszek
    • Małgorzata Pułka
    2018 Bulletin of the Malaysian Mathematical Sciences Society

    This paper is devoted to the study of the problem of prevalence in the class of quadratic stochastic operators acting on the L1 space for the uniform topology. We obtain that the set of norm quasi-mixing quadratic stochastic operators is a dense and open set in the topology induced by a very natural metric. This shows the typical long-term behaviour of iterates of quadratic stochastic operators.

  • Prezentacja akwareli pt. Miłość istnieje! Kurwa! na wystawie sztuki współczesnej
    • Patryk Różycki
    2018

  • Prezentacja działania performance pt. Wstydzę się
    • Patryk Różycki
    2018

  • Prezentacja dzieła artystycznego pt. Tęsknię za Tobą,
    • Patryk Różycki
    2018

  • Prezentacja performance pt. Pisanie listów
    • Patryk Różycki
    2018

  • Prezentacja pracy wideo pt: Turkusowy pokój
    • Patryk Różycki
    2018

  • Prezentacja zespołu prac malarskich, rysunkowych i tekstowych pt. Osobisty poradnik jak nie dostać depresji turysty
    • Patryk Różycki
    2018

  • Probabilistic Analysis of Structure Models using Target Random Sampling (TRS)
    • Magdalena Oziębło
    • Karol Winkelmann
    • Jarosław Górski
    2018

    The work presents testing methods of sensitivity and reliability of mechanical or structural systems. All computations concerned the case of Zigler column, a simple model of a compressed column involving two random variables only. A conclusion was drawn that the standard Monte Carlo method, its reduction variants and the response surface method allow to assess the sensitivity of structural response to the variation of random structural parameters. Sensitivity assessment was proposed on the basis of Sobol sensitivity indices and the analysis of limit state surface intersections.

  • Probabilistic Methods in Reliability Assessment of Engineering Lightweight Structures
    • Karol Winkelmann
    2018

    The paper considers the probability-based analysis of structural safety measures. Two different numerical examples of representative lightweight structures are considered – a submerged truss tower supporting an offshore platform, and an overhead power line support truss tower. On the basis of these examples, the importance of a motivated selection of analysis method and a proper choice of the number of important variables is shown. Moreover, formulation of the reliability index related to the response of a considered structure is presented, alongside the possibility of adjusting the random methodology to the given task. The structures under consideration are burdened with uncertainties – material and load imperfections. Additionally, the simulation is performed of the impact of chosen imperfections to the structural reliability decrement in the time of structural service. Such an applicability overview of random methodology is performed to show that even a diverse structural domain may be analysed by a versatile random approach. Moreover, proper reliability estimation is possible even for specifically simplified cases.

  • Probabilistyczna ocena wrażliwości stanów granicznych konstrukcji inżynierskich na imperfekcje geometryczne i materiałowe
    • Magdalena Oziębło
    2018 Pełny tekst

    Tematem pracy jest analiza probabilistyczna wrażliwości mechanicznej odpowiedzi konstrukcji inżynierskich na imperfekcje geometryczne oraz zmianę własności materiałów. Z tematem tym ściśle związany jest problem estymacji niezawodności konstrukcji, również szeroko opisany w rozprawie. W pracy dokonano przeglądu metod wykorzystywanych w analizie probabilistycznej oraz zaproponowano procedury wykorzystujące te metody w analizie wrażliwości niezawodnościowej. Opisane zostały kolejno: metoda Monte Carlo (MC), metody redukcyjne próbkowania warstwowego (SS) i hipersześcianu łacińskiego (LHS), metoda estymacji punktowej (PEM) oraz metoda powierzchni odpowiedzi (RSM). Najwięcej uwagi poświęcono technice próbkowania ukierunkowanego (TRS – Targeted Random Sampling), na podstawie której stworzono program komputerowy w środowisku MATLAB, umożliwiający poszukiwanie próbek w otoczeniu stanu granicznego konstrukcji. Osobny rozdział poświęcono klasyfikacji i omówieniu technik analizy wrażliwości, m.in. analizy jednoczynnikowej, projektowania przesiewowego oraz analizy wariancji. Przedstawione metody probabilistyczne wykorzystano w analizie kilku przykładów modeli prętowych: kratownicy von Misesa, kolumnie Zieglera, wieży telekomunikacyjnej i kopuły prętowej. Wskazano optymalne sposoby określania wrażliwości mechanicznej odpowiedzi układu na zmiany poszczególnych zmiennych losowych. We wnioskach podsumowano przeprowadzone obliczenia oraz określono kierunki dalszych prac, których nadrzędnym celem powinna być implementacja metod probabilistycznych w standardowym projektowaniu konstrukcji.

  • PROBABLE RAINFALL IN GDAŃSK IN VIEW OF CLIMATE CHANGE
    • Wojciech Szpakowski
    • Michał Szydłowski
    2018 Pełny tekst Acta Scientiarum Polonorum Formatio Circumiectus

    One of the manifestations of climate changes is the occurrence of a greater number of precipitation events, characterized by greater rain intensity that affects the economic stability of cities. Gdańsk is an example of a city in which such events have occurred since the beginning of the twenty-first century. Due to the altitude differences in the area of Gdańsk city (between –2 m and 180 m a.s.l.), the occurrence of extreme atmospheric precipitation almost immediately causes hydrological effects in the water network consisting of several streams of montane character, which flow eastwards from the plateau of the Kashubian Lakeland. Meteorological stations of the National Meteorological Service (IMGW-PIB) are located in the coastal zone (Port Północny/Northern Port, Świbno) and in the highest part of the city (the Rębiechowo airport). Because this is insufficient, the city of Gdańsk has been expanding the local rain monitoring network since 2001, currently having reliable 10-year observation data sequences. The said network is operated by the Gdańsk Water municipal company. Climate changes resulting in different characteristics of rainfall episodes in Gdańsk naturally influence the determination of the probability of their occurrence. According to the rainfall model developed by Bogdanowicz and Stachy at the turn of the 20th and 21st centuries, at least 4 rainfall events lasting for over 8 hours in the last 17 years should be classified as a 100-year rain event. One of these extended the parameters of a 300-year rain event; whereas we asses the rain in the year 2016, when even 170 mm of rainfall was recorded on July 14, as at least a 500-year rain event. During this period, several-minute events were also recorded, which also exceeded the parameters of a 100-year rain event. The paper presents precipitation models for the region of Gdańsk. Based on the maximum annual daily rainfall from Rębiechowo meteorological station from the years 1974–2017, an analysis of changes in precipitation values corresponding to certain probabilities of occurrence was conducted. An assessment was also made of the projected decrease in the value of precipitation in relation to hydro-technical constructions, road-engineering structures, and rainwater drainage systems in view of changing legal regulations, as well as the latest trends related to the management of rainwater.

  • Problem wód opadowych w nowym prawie wodnym
    • Ziemowit Suligowski
    2018

    Konsekwencje wprowadzenia nowej ustawy prawo wodne dla zagadnień związanych z gospodarka wodami opadowymi. Analiza porównawcza w stosunku do starszych regulacji prawnych i praktyki. Dodatkowo zamieszczony wykaz 45 aktów prawnych zmienionych w konsekwencji wprowadzenie nowej ustawy.

  • Problems and chellenges to determine pesticide residues in bumblebees
    • Żaneta Bargańska
    • Dimitra Lambropoulou
    • Jacek Namieśnik
    2018 CRITICAL REVIEWS IN ANALYTICAL CHEMISTRY

    Bumblebees play an important role in t he pollination process of many crops and flowers. Therefore, taking action to protect and assess the impact of p esticides on these insects is fully justi fied. Pesticides may cause mortality and also sub-lethal effects that are not always directly visible. Bumblebees, like honeybees, can be used as indicators for environmental monitoring contamination. Two approaches are mainly used for the determination of pesticide residues in pollinating insects: a toxicological test (to know effects) and multi-stage analytical methodologies (to know exposure). The development of new analytica l procedures that would use of sample preparation techniques meeting the requirements of green chemistry or the improvement of existing analytical methods; this is a challenge for analytical chemists. However, such activities can be helpful in developing legal norms regarding the maximum residue levels of pesticides in wild bee organisms.

  • Problems and Solutions of Software Design in Scrum Projects
    • Jakub Miler
    • Kamil Kajdy
    2018 Pełny tekst Annals of Computer Science and Information Systems

    The aim of the paper is to identify the problems and solutions of the software design in Scrum project as well as to analyze the effectiveness of the solutions. Through a series of workshops with 4 experts from IT industry and academia we have identified 52 problems and 99 unique solutions. In this paper we present a list of 10 common problems and 5 solutions for each problem selected by the number of sources. The effectiveness of the solutions to the given problems was evaluated in an opinion survey by 39 respondents with experience both in software design and in the Scrum framework. This evaluation provided for our initial recommendations on the choice of solutions to particular problems.

  • PROBLEMY EKSPLOATACYJNE W ROZJAZDACH KOLEJOWYCH
    • Sławomir Grulkowski
    • Kamil Hajduk
    2018

    W artykule zaprezentowano pojawiające się nowe charakterystyczne formy zużyć elementów rozjazdów kolejowych, związane z odmiennymi (zwiększonymi) parametrami eksploatacyjnymi. Omówiono także problemy organizacyjne napraw elementów nawierzchni kolejowej.

  • Problemy konstrukcyjne zastosowania kanalizacyjnej studzienki rewizyjnej
    • Ziemowit Suligowski
    2018 Pełny tekst Inżynier Budownictwa

    Konstrukcja kanalizacyjnej studzienki rewizyjnej. Charakterystyczne grupy obiektów. Konsekwencje, specyfika posadowienia, warunki eksploatacji. Posadowienie

  • PROBLEMY WYKONYWANIA AUDYTÓW ENERGETYCZNYCH W OBIEKTACH PRZEMYSŁOWYCH
    • Paweł Bućko
    • Izabela Sadowska
    2018 Pełny tekst Rynek Energii

    W artykule zestawiono informacje obejmujące ramy prawne wykonania audytów energetycznych w zakładach przemysłowych. Opisano główne założenia dokumentów formalnych, a także zinterpretowano kluczowe fragmenty. Odniesiono zapisy prawa do rzeczywistych możliwości ich zastosowania. Zamiarem autorów było, aby zamieszczone uwagi wskazywały najważniejsze problemy wykonywania audytów przemysłowych, z którymi spotyka się audytor. Dotyczy to zarówno procedury, metodyki, jak i możliwości ich skutecznej realizacji w typowych uwarunkowaniach krajowych.