Wpływ laboratoryjnych metod zagęszczania na właściwości fizykomechaniczne recyklowanych mieszanek mineralno-asfaltowych z asfaltem spienionym

This study attempts to evaluate the influence of two advisable methods for compacting laboratory specimens of road base recycled mixes with foamed bitumen (MCAS) and bitumen emulsion (MCE). The obligatory regulations for this technology permit fabrication of the specimens using either an impact Marshall compactor or a static hydraulic press. The research showed that the compaction method influenced both the physical and mechanical properties of samples regardless of the type of bitumen binder. What is more, the structure of the material changed after the impact compaction process, which manifested in fact that many of the aggregate particles were crushed in its course. Better strength and resistance to moisture damage was observed in samples prepared in the hydraulic press. This was associated with lower void contents obtained in this compaction method.W referacie przedstawiono wyniki badań oceny wpływu laboratoryjnych metod zagęszczania na właściwości recyklowanych mieszanek z asfaltem spienionym (MCAS) oraz z emulsją asfaltową (MCE). Obecne wymagania opracowane i stosowane w naszym kraju przy realizacji zadań drogowych na etapie projektowania składu mieszanek oraz kontroli właściwości wykonywanej warstwy podbudowy w technologii recyklingu na zimno dopuszczają dwie metody formowania prób w warunkach laboratoryjnych: zagęszczanie statyczne prasą hydrauliczną oraz udarowe w ubijaku Marshalla. Na podstawie badań stwierdzono, iż rodzaj metody zagęszczania ma wpływ na cechy fizyczne i mechaniczne recyklowanych mieszanek. Zaobserwowano również, że sposób formowania prób wpływa na strukturę uzyskanego materiału, gdzie znaczny udział ziaren materiału mineralnego uległ rozkruszeniu podczas zagęszczania udarowego. Próbki zagęszczane w sposób statyczny uzyskały lepsze parametry wytrzymałościowe oraz charakteryzowały się wyższą odpornością na działanie wody, co ma związek z niższą zawartością wolnych przestrzeni uzyskiwaną w próbkach zagęszczanych tą metodą

15 Years of the Polish agricultural biogas plants: their history, current status, biogas potential and perspectives

Biogazownie rolnicze w Polsce

Energia odnawialna w województwie warmińsko-mazurskim, 158 s.

Energetyka odnawialna (OZE) jest szeroko rozwijana na świecie, w tym również w Polsce. W najbliższych latach przewiduje się dalszy rozwój OZE w Polsce. Stąd też zrodził się pomysł napisania niniejszej monografii. Pierwszym celem przeprowadzonych badań było wyznaczenie potencjału technicznego energii odnawialnej w Polsce. W przypadku biomasy założono, że w większym stopniu należy wykorzystać biomasę odpadową oraz zagospodarować grunty ugorowane i nieużytki. Obliczono również potencjał techniczny aeroenergetyki w Polsce z wykorzystaniem metody GIS na podstawie danych uzyskanych z IMGW. W przypadku helioenergetyki i pomp ciepła przyjęto, że panele fotowoltaiczne, kolektory słoneczne i pompy ciepła należy montować na istniejących budynkach użyteczności publicznej i obiektach nowo budowanych Drugim celem badań było przeprowadzenie ankiet socjometrycznych. W latach 2009–2018 przygotowano i wysłano ankiety do firm, właścicieli urządzeń OZE w Polsce, rolników, uczniów i nauczycieli. Trzecim celem badań było przeprowadzenie analizy SWOT i PEST energetyki odnawialnej w Polsce

Synergistic Effect of F–T Synthetic Wax and Surface-Active Agent Content on the Properties and Foaming Characteristics of Bitumen 50/70

The level of the properties of bituminous mixtures produced with water foamed bitumen relies on the optimum characteristics of the bitumen. One way to achieve the desired characteristics is to modify the bitumen with chemical additives before it is foamed. Bitumen 50/70 treated with a surface-active agent (SAA) at 0.2%, 0.4% and 0.6% and Fischer–Tropsch (F–T) synthetic wax at 1.5%, 2.0%, 2.5% and 3.0% was used in the tests. The effect of the modifiers was investigated by assessing bitumen properties (penetration, softening point, Fraass breaking point and dynamic viscosity at 60 °C, 90 °C and 135 °C) and foam parameters (maximum expansion—ER, half-life—HL). For statistical evaluation of the test results, models of the properties of bitumen 50/70 were developed as a function of the contents of F–T synthetic wax and SAA. It was found that 2.0% F–T wax and 0.6% SAA were optimum contents for achieving the desired standard properties and foam characteristics of the tested binder. The developed models allow determining the composition of the modified binder depending on the required foam characteristics for specific applications in road construction. The recommended composition of the chemical additives used to modify the binder was also established to ensure its optimum properties

Doubly Fed Induction Machine-Based DC Voltage Generator with Reduced Oscillations of Torque and Output Voltage

The doubly fed induction machine (DFIM)-based DC voltage generator is equipped with a stator-connected diode rectifier. The six-pulse diode rectifier as a nonlinear circuit introduces harmonics in the stator and rotor current and distorts the machine stator voltage, as well as the stator flux. This causes electromagnetic torque oscillations and instantaneous power components oscillations. The torque oscillations adversely impact the mechanical parts of the drive-train and oscillations of the p component of instantaneous power influence DC-bus voltage oscillations. The oscillations can be somewhat cancelled by control methods. However, cancellation of electromagnetic torque is not strictly coupled with cancellation of oscillations of the p component of instantaneous power. The paper presents an analysis of influence of the control methods aimed at a reduction of torque oscillations on the output voltage oscillations level in the stand-alone DFIM-based DC voltage generator. Field-oriented control FOC with current controllers and space vector modulation-based direct torque control DTC-SVM with flux module regulation have been compared with control in which electromagnetic torque is one of the commanded variables, whereas the second variable is the dot product of stator flux and rotor current space vectors. The contributions of this paper are the introduction of a new variable in the second control path in the DTC-SVM method instead of flux vector length and the proof that it can reduce torque and DC-bus voltage oscillations in the DFIG-DC system. Additionally, this paper reveals that for proper stator-to-rotor-turns ratio of a doubly fed machine necessary for reduction of the rotor converter power, lower DC-bus voltage can be obtained than is required for full realization rotor side voltage requested by rotor current controllers. This is the reason why, regardless of the control method, torque oscillations cannot be always fully cancelled, and a comparative study of the methods at these conditions has been conducted in simulation and in laboratory tests

Effect of Surface Active Agent (SAA) on 50/70 Bitumen Foaming Characteristics

To ensure the standard properties of half-warm asphalt (HWA) mixes produced with foamed bitumen, the binder needs to have the best possible characteristics. One way to attain this is to modify the bitumen before it is foamed. The 50/70 penetration bitumen used in this study, was modified with a surface active agent (SAA) at different rates (0.2%, 0.4%, and 0.6% by wt.). The effect of the modifier on the bitumen properties (penetration, softening point, the Fraass breaking point, dynamic viscosity at 60 °C, 90 °C, and 135 °C) and on the binder foaming parameters (expansion ratio - ER, half-life - HL, foam index - FI) was investigated and the optimum quantity of foaming water was determined. Statistical analysis of the results showed that the addition of 0.6% SAA had the most beneficial effect on the set of 50/70 bitumen standard properties and foaming characteristics

Neolityczna kopalnia krzemienia czekoladowego „Oszybka” w Pakosławiu w województwie mazowieckim w świetle badań Marcina Bednarza – nowe spojrzenie na stare materiały terenowe

Kopalnia “Oszybka” w Pakosławiu województwo mazowieckie została odkryta w 1992 roku przez Marcina Bednarza w czasie badań powierzchniowych realizowanych przez studentów z Instytutu Archeologii Uniwersytetu Warszawskiego. W kolejnych trzech sezonach badawczych pozyskano około 1750 przedmiotów krzemiennych. Ten duży zbiór zawierał nie nie tylko charakterystyczne rdzenie, ale także produkty debitażu. Wstepne analizy materiału wskazywały na chronologię związaną z późnym mezolitm lub wczesnym neolitem. Po latach zespół archeologów z Instytutu Archeologii z Uniwersytetu Kardynała Stefana Wyszyńskiego z Warszawy powrócił do studiów nad tymi materiałami. Dzięki szczegółowej dokumentacji z lat 90-tych była możliwa digitalizacja i implementacja wyników do środowiska GIS. Rezultem tej procedury była możliwość analizy przestrzennej materiałów krzemiennych połączona ze studiami technologicznymi i typologicznymi.The flint mine “Oszybka” in Pakosław, Mazowieckie voievodeship was discovered by Marcin Bednarz in 1992 during a field survey on an outcrop of chocolate flint conducted by students practice from Institute of Archaeology University of Warsaw. During the next three seasons about 1750 flint artifacts were collected from the site. This large assemblage contains not only the characteristic forms like cores but also debitage products. Initial research made it possible to determine the chronology of site as belonging to late Mesolithic and/or early Neolithic. Further studies were sadly interrupted by the premature death of Marcin Bednarz. After some years, according to Marcin wishes, team from the Institute of Archaeology Cardinal Stefan Wyszyński University in Warsaw returned to the studies of flint materials from the “Oszybka” flint mine. Thanks to very detailed documentation from the 90s of the last century has become possible to digitalize and integrate it into a GIS environment. As a result, we acquired many spatial analysis of flint materials and combined them with research in terms of technology and typology

Effects of zeolites and hydrated lime on volumetrics and moisture resistance of foamed warm mix asphalt concrete

The paper concerns the utilization of hydrated lime and zeolites as additives in warm mix asphalt produced with foamed bitumen. The mentioned additives were added to the mixtures in exchange for specific quantities of mineral filler, which amounted to 0.4% and 1.2% of hydrated lime or 0.4% of water-modified and 1.0% of air-dry zeolites in mineral mix. The study investigated warm-produced mixtures with 4.5% and 4.8% binder content and production and compaction temperatures set at 120⁰C and 100⁰C respectively. Additionally, reference hot and warm mixtures were evaluated. The testing included: air void content, indirect tensile strength in dry state and after one freeze-thaw cycle as well as the resulting resistance to moisture and frost damage index. The mixtures incorporating hydrated lime and lower bitumen content of 4.5% exhibited increased air voids and mostly unchanged mechanical performance when compared to the reference warm mix. Increased bitumen content has resulted in significantly improved performance in moisture resistance and compactability which could be compared to that of the reference hot-produced mixture. On the other hand, the incorporation of zeolites in the foamed bitumen mixtures resulted in all cases in increased air void content in the samples. This has apparently led to decreased indirect tensile strength, in both the dry state and after the freeze-thaw cycle. Based on the results it was concluded that the production temperature of the zeolite-bearing mixtures was too low for the zeolite water to significantly improve the mix’ workability and therefore positively affect its mechanical parameters