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Publications from the year 2018
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Turán numbers for odd wheels
- Tomasz Dzido
- Andrzej Jastrzębski
The Turán number ex(n,G) is the maximum number of edges in any n-vertex graph that does not contain a subgraph isomorphic to G. A wheel W_n is a graph on n vertices obtained from a C_{n−1} by adding one vertex w and making w adjacent to all vertices of the C_{n−1}. We obtain two exact values for small wheels: ex(n,W_5)=\lfloor n^2/4+n/2\rfloor, ex(n,W_7)=\lfloor n^2/4+n/2+1 \rfloor. Given that ex(n,W_6) is already known, this paper completes the spectrum for all wheels up to 7 vertices. In addition, we present the construction which gives us the lower bound ex(n,W_{2k+1})>\lfloor n^2/4 \rfloor + \lfloor n/2 \rfloor in general case.
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Turbulence models impact on the flow and thermal analyses of jet impingement
- Tomasz Kura
- Elżbieta Fornalik-Wajs
- Jan Wajs
- Sasa Kenjeres
Accurate numerical reconstruction of heat and mass transfer processes in particular applications, such a jet impingement, is difficult to obtain even with the use of modern computational methods. In the proposed paper, the flow and thermal phenomena occurring during single minijet impingement on the flat, concave and convex, heated surfaces were considered. Problem of impingement on non-flat surface, still not common and purely described in the literature, can be of big importance in engineering applications, such as the heat exchangers. Numerical analyses, based on the mass, momentum and energy conservation laws, were conducted with the OpenFOAM software. Focus was placed on the proper model construction, in which turbulence and boundary layer modelling was crucial, due to their significance in the heat transfer processes. Analysis of results obtained by RANS models focused mostly on the comparison of turbulent and hydrodynamics parameters.
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Turmeric nanofiber-encapsulated natural product formulation act as a phytogenic feed additive—A study in broilers on growth performance, biochemical indices of blood, and E. coli in cecum
- Sreeraj Gopi
- Augustine Amalraj
- Karthik Varma
- Shintu Jude
- Prakash Reddy
- Chandradhara Divya
- Józef Haponiuk
- Sabu Thomas
A phytogenic feed additive (PFA) formulation was prepared with bioactive molecules—curcuminoids, gingerol, and carvacrol by encapsulating in nanofiber isolated from turmeric spent (turmeric nanofiber, TNF). This formulation was completely characterized by scanning electron microscope, ultra performance liquid chromatography, and gas chromatography and evaluated for its efficacy. PFA-encapsulated TNF (PFA@TNF) considerably increased mean body weight, decreased cholesterol level, mortality rate, and reduced Escherichia coli content of broilers than antibiotic growth promoter (AGP). The depth of crypts in the ileum of broilers was considerably reduced by the inclusion of PFA@TNF in diets compared with the AGP.
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Two-Dimensional Gas Chromatography Coupled With Mass Spectrometry in Food Analysis
- Tomasz Dymerski
The development of instrumental analytical techniques provided the opportunity for in-depth characterization of many food matrices. In particular, the use of gas chromatography coupled with mass spectrometry gives impressive results in terms of quality and authenticity testing, conducting food freshness evaluations and contamination assessments. A new variant of gas chromatography, namely two-dimensional gas chromatography (GC × GC), and various versions of mass spectrometry have been developed since last 15 years, and they still remain at the time of their renaissance. The present critical review is focused on the use of GC × GC coupled with mass spectrometry for qualitative and quantitative reasons in food analysis. It is explained how powerful analytical tool is above-mentioned technical solution. Special attention is devoted to the issues related to the development of this technique during last years in terms of key construction elements, such as modulators and MS detectors. Finally, the critical discussion on many various aspects including advantages and more important disadvantages, caused probable moderate interest of this solution, in food analytics is concerned.
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Two-dimensional hydrogen-like atom in a weak magnetic field
- Radosław Szmytkowski
We consider a non-relativistic two-dimensional (2D) hydrogen-like atom in a weak, static, uniform magnetic field perpendicular to the atomic plane. Within the framework of the Rayleigh-Schr¨odinger perturbation theory, using the Sturmian expansion of the generalized radial Coulomb Green function, we derive explicit analytical expressions for corrections to an arbitrary planar hydrogenic bound-state energy level, up to the fourth order in the strength of the perturbing magnetic field. In the case of the ground state, we correct an expression for the fourth-order correction to energy available in the literature.
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Two-Stage Identification of Locally Stationary Autoregressive Processes and its Application to the Parametric Spectrum Estimation
- Maciej Niedźwiecki
- Marcin Ciołek
The problem of identification of a nonstationary autoregressive process with unknown, and possibly time-varying, rate of parameter changes, is considered and solved using the parallel estimation approach. The proposed two-stage estimation scheme, which combines the local estimation approach with the basis function one, offers both quantitative and qualitative improvements compared with the currently used single-stage methods.
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Two-step Conversion of Crude Glycerol Generated by Biodiesel Production into Biopolyols: Synthesis, Structural and Physical Chemical Characterization
- Aleksander Hejna
- Paulina Kosmela
- Marek Klein
- Krzysztof Formela
- Milena Kopczyńska
- Józef Haponiuk
- Łukasz Piszczyk
In this work biopolyols were synthesized via two-step process from crude glycerol and castor oil. For better evaluation of analyzed process, the impact of its time and temperature on the structure and properties of biopolyols was determined. Obtained results fully justified conducting of synthesis in two steps. Prepared materials were characterized by hydroxyl value and water content comparable to polyols industrially applied in manufacturing of polyurethane materials. Synthesized biopolyols were characterized in terms of their chemical structure using spectroscopic techniques: Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance spectroscopy. Obtained data confirmed the influence of synthesis’ parameters on the chemical structure of prepared biopolyols and correlated with their other parameters. On both stages of reaction, collected by-products were also analyzed with FTIR spectroscopy.
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Types of Surface Impurities versus the Quality of Brazed Joints
- Jacek Tomków
- Jacek Haras
Brazing is one of the primary joining processes increasingly often applied in industry. Because of their mechanical properties, overlap joints are particularly popular when making brazed structures. The use of brazed joints in structures of critical importance requires that particular attention be paid to joint quality, e.g. by the appropriate cleaning of surfaces to be joined. The article presents results of non-destructive tests of brazed joints made in steel S235JRG2. Surfaces used in the tests were deliberately contaminated to simulate the presence of welding imperfections. Afterwards, the test specimens were subjected to non-destructive (visual and radiographic) tests aimed to determine the effect of surface impurities on the quality of brazed joints.
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UAV Design and Construction for Real Time Photogrammetry and Visual Navigation
- Paweł Burdziakowski
A unmanned aerial vehicles applications in photogrammetry have increased rapidly last years. A fast data gathering and processing in real time in some cases become crucial and desired in some application. In the paper, a real time solution is proposed. A real time photogrammetry from UAV is proposed, where image data are gathered and processed on board UAV and finally reconstructed 3D model and measurements are delivered. The paper presents the design of sUAV (small unmanned air vehicle) for real time photogrammetry, visual navigation, real-time spectral data processing. Construction is based on newly designed quadcopter frame based on the experience and previous research, using CAD/CAM. No image data are transferred out of the board and overall photogrammetry process is calculated on board. Finally three dimensional measurements are delivered to the user in the same time, as sUAV flies, or in specified time just after the sUAV has landed.
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UAV IN TODAYS PHOTOGRAMMETRY – APPLICATION AREAS AND CHALLENGES
- Paweł Burdziakowski
There a few important factors, that nowadays, unmanned aerial vehicles (UAV) are used by wider community, and for cases and applications, that cannot be performed never before. Small UAVs, as a photogrammetry measurement tool provide flexibility, reliability, are safe and easy to use, can be deployed in minutes, initial measurement can be delivered yet on the field, and final accurate measurements are calculated in a very short time, even using online services. A numerous cases was studied on Department of Geodesy at Gdansk University of Technology using popular and commercial drones. All cases was analyzed using modern methods, and the results was compared to laser scans measurements. The paper presents results, including challenges and conclusions for each studied case, especially for geodesy, architecture, heritage conservation, civil engineering, police work, forensic analysis and natural science.
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UKŁAD I PROGRAM DO WYZNACZANIA PARAMETRÓW SCHEMATU ZASTĘPCZEGO SUPERKONDENSATORA
- Karol Przybylski
- Arkadiusz Szewczyk
W pracy przedstawiono prototyp urządzenia do wyznaczania parametrów schematu zastępczego superkondensatora na podstawie jego charakterystyk ładowania i rozładowania. Urządzenie składa się ze sterowanego źródła prądowego do ładowania i rozładowywania superkondensatora, przetwornika analogowo-cyfrowego do pomiaru prądu i napięcia w trakcie eksperymentu oraz mikroprocesora do sterowania pomiarem i komunikacji z komputerem na którym uruchomiony jest program sterujący. W celu sprawdzenia poprawności działania wykonanego prototypu urządzenia przeprowadzono szereg pomiarów dla wybranych dostępnych w handlu superkondensatorów. Przeprowadzone badania potwierdziły poprawność pracy zaprojektowanego układu.
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Ulga podatkowa jako mechanizm stymulowania zachowań mikro i małych przedsiębiorstw. Prezentacja wyników badań
- Piotr Kasprzak
Cel – Celem niniejszego artykułu jest prezentacja wyników badań przeprowadzonych w okresie styczeń–kwiecień 2018 roku. Celem badania było zdefiniowanie, przedstawienie i określenie stymulacyjnej roli podatku dochodowego realizowanej za pośrednictwem ulg i zwolnień podatkowych w polskim systemie podatkowym w stosunku do przedsiębiorstw sektora MŚP. Autor za cel dodatkowy postawił wskazanie możliwości, z których mogą korzystać przedsiębiorstwa sektora MŚP w zakresie mechanizmów ulg i zwolnień oraz określenie świadomości polskich przedsiębiorstw sektora mikro i małych firm w zakresie możliwości korzystania z ulg i preferencji podatkowych, a także zidentyfikowanie przesłanek i barier stosowania mechanizmów ulg i zwolnień podatkowych. Metodologia badania – Metodyka obejmuje empiryczne badania o charakterze jakościowym zrealizowane za pośrednictwem kwestionariusza skierowanego do sektora mikro i małych przedsiębiorstw. Niniejszy artykuł uzupełniono o przeprowadzone studia literaturowe. Wynik – Wyniki przeprowadzonego badania wskazują, iż poziom wykorzystania ulg i zwolnień wśród przedsiębiorstw sektora MŚP jest niski. Najczęściej spowodowane jest to zarówno brakiem wiedzy w tym zakresie, jak i wysokim poziomem skomplikowania procedur biurokratycznych. Badani przedsiębiorcy potrafią jednak co do zasady wskazać wybrane metody obniżania zobowiązań podatkowych z wykorzystaniem ulg i zwolnień. Wyniki badania wskazują także postulowany przez przedsiębiorców kierunek i zakres zmian w omawianym obszarze. Oryginalność/wartość – Przeprowadzone przez autora badania miały charakter pilotażowy, a ich wyniki mogą stanowić bazę do dalszych, bardziej pogłębionych analiz.
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Unassisted formation of hemiaminal ether from 4-aminopyridine and o-vanillin - experimental and theoretical study
- Agnieszka Mielcarek
- Aleksandra Wiśniewska
- Anna Dołęga
The reactions between o-vanillin and three isomeric aminopyridines lead to imines of diverse spatial conformation and reactivity. The direct products of these simple reactions carried out in methanol are either imine compounds formed in the reactions of 2- amino- and 3-aminopyridine with o-vanillin or the α-aminoether formed in the reaction of o-vanillin with 4-aminopyridine. The Schiff-type derivative of 4-aminopyridine and o-vanillin, which is described in this paper for the first time, is very reactive and can only be obtained indirectly from the α-aminoether in anhydrous conditions. All compounds are characterized by X-ray diffraction and FT-IR and NMR spectroscopies. The DFT calculations at all-electron BLYP/Q4ZP level of theory are utilized to explain the differences between the reactivity of isomeric aminopyridines and their imine derivatives.
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Uncertainty of the liquid mass flow measurement using the orifice plate
- Anna Golijanek-Jędrzejczyk
- Dariusz Świsulski
- Robert Hanus
- Marcin Zych
- Leszek Petryka
The article presents an estimation of measurement uncertainty of a liquid mass flow using the orifice plate. This subject is essential because of the widespread use of this type of flow meters. Not only the quantitative estimation but also the qualitative results of those measurements are important. To achieve these results the authors of the paper propose to use the theory of uncertainty. The article shows the analysis of the measurement uncertainty using two methods: one based on the ‘Guide to the expression of uncertainty in measurement’ (GUM) of the International Organization for Standardization by means of the law of propagation of uncertainty, and the second one by means of the Monte Carlo numerical method. The paper presents a comparative analysis of the results obtained by employing both of these methods for the centric and eccentric orifice plate. In both of the examples, the resulting uncertainty of flow measurement is approximately 1%. The uncertainty determined by the analytical method was higher than what was obtained from the Monte Carlo simulations with a difference of 0.04%.
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Underwater Navigation System Based on Doppler Shifts of a Continuous Wave
- Zawisza Ostrowski
- Jacek Marszal
- Roman Salamon
The paper describes a concept of an underwater navigation system designed to determine the location and speed of its ROVs or divers. Conducted by the Department of Marine Electronic Systems at the Gdansk University of Technology for several years, research has focused on navigation systems which determine positions on the basis of Doppler shifts of echo signals reflected from a moving object. This article presents a different version of such a system. With a source of a sinusoidal acoustic wave placed on a moving object, four hydrophones, transmitting and receiving electronics and a computer, the system determines Doppler deviations of the received signals and calculates the position and speed of the moving object. Simulation studies and experiment results have shown that the system can offer an alternative solution for tracking its underwater objects.
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Uniform sampling in constrained domains for low-cost surrogate modeling of antenna input characteristics
- Sławomir Kozieł
- Ari Sigurdsson
- Stanisław Szczepański
In this letter, a design of experiments technique that permits uniform sampling in constrained domains is proposed. The discussed method is applied to generate training data for construction of fast replacement models (surrogates) of antenna input characteristics. The modeling process is design-oriented with the surrogate domain spanned by a set of reference designs optimized with respect to the performance figures and/or operating conditions that are of interest. The reference designs are triangulated and the resulting simplexes are extended in orthogonal directions. Our methodology is demonstrated using two examples: a dual-band dipole and an ultra-wideband monopole. The results indicate that the proposed sampling technique leads to considerable improvement of the surrogate model predictive power as compared to random sampling. Numerical results are supported by application studies (antenna optimization) and experimental validation.
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UN’IPERTROFIA INEVITABILE? LA MOBILITAZIONE INDUSTRIALE E LA TRASFORMAZIONE DELL’APPARATO AMMINISTRATIVO PER LO SFORZO BELLICO
- Luciano Segreto
Il capitolo esamina le trasformazioni dell'apparato amministrativo in relazione alle esigenze dello sforzo bellico
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Uniwersalna metoda obliczania wartości prądów w przewodach odgromowych linii napowietrznych
- Jacek Klucznik
W artykule przedstawiono nowatorską metodę obliczania wartości prądów płynących w przewodach odgromowych linii elektroenergetycznych w czasie zwarć. Metoda może być stosowana dla złożonych układów sieciowych, składających się z kilku stacji oraz różnych typów linii. Analizowane mogą być linie jedno- i dwutorowe z jednym bądź dwoma przewodami odgromowymi. Metoda pozwala na dobór przewodów odgromowych pod względem wytrzymałości cieplnej z mniejszym ryzykiem niepewności niż powszechnie stosowane metody. Prezentowana metoda obliczeniowa pozwala również na ocenę ochrony przeciwporażeniowej linii, poprzez wyznaczenie wartości prądów płynących w uziomach słupów.
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Unravelling the role of electron–hole pair spin in exciton dissociation in squaraine-based organic solar cells by magneto-photocurrent measurements
- Maciej Klein
- Sayani Majumdar
- Paweł Zassowski
- Waldemar Stampor
A high absorption coefficient and narrow absorption bands in squaraine (SQ) dyes have resulted in rapidly growing interest in them as a donor material in photovoltaic devices. The exciton dissociation process in organic systems proceeds via a multistep mechanism where the electron–hole pairs (charge transfer states) involved in the current generation process determine the recombination losses and subsequently limit the overall performance of organic solar cells. In this work, these basic electronic processes are investigated by magneto-photocurrent measurements (MPC, the photocurrent change induced by the external magnetic field) of SQ:PC60BM bulk-heterojunction solar cells with varying electron acceptor concentrations under magnetic fields up to 9 T and at different temperatures. Under a weak external magnetic field, the change in photocurrent is due to electron and hole (e–h) pairs that experience a modulating hyperfine interaction associated with nuclear (mainly proton) magnetic moment, while in strong magnetic fields the photocurrent is affected by the Δg mechanism with spin dephasing due to different Lande factors of the electron and hole entities (Δg ≈ 10−3). To consistently interpret the amplitudes and lineshapes of the MPC signals at various temperatures, charge carrier hopping in a disordered environment competing with the magnetic dipole spin precession is proposed. The requirements for efficient small-molecular weight organic:fullerene bulk-heterojunction solar cells are briefly discussed.