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    Wyświetlanie 1-8 z 8
    Tytuł:
    Analysis of Rheological Properties of Cement Composites Based on Waste Materials
    Autorzy:
    Zakrzewski, Mateusz
    Domski, Jacek
    Powiązania:
    https://bibliotekanauki.pl/articles/27322945.pdf
    Data publikacji:
    2023
    Wydawca:
    Politechnika Koszalińska. Wydawnictwo Uczelniane
    Tematy:
    cement composites
    creep
    steel cord
    fiber-reinforcement concrete
    long-term study
    concrete beams
    waste aggregate
    waste fibers
    crack
    Opis:
    This report presents the results and analysis of long-term properties of fiber-reinforced cement composite based on waste aggregate. The long-term tests were carried out on the stand proposed by the authors for simultaneously testing three beams with dimensions of 100x200x2900 mm. A total of 8 mixtures of cement composites with aggregate from ceramic waste and waste sand were tested. Three beams were made for each mixture. One without dispersed reinforcement and two with 0.5% and 1.0% fiber reinforcement ratios. As dispersed reinforcement, steel cord and hooked steel fibers were used. The beams were subjected to a four-point bending test. The research was carried out for 1000 days. An optical system was used as an innovative solution in long-term research. Based on the measurements, the creep coefficient in the mid-span of the beams was determined, and the crackings of the beams were analysed. The results obtained using manual measuring devices and the optical system were compared. A good convergence of measurement methods was observed. During the analysis of the results, the coefficients modifying the method for calculating the crack width included in Eurocode 2 were determined.
    Źródło:
    Rocznik Ochrona Środowiska; 2023, 25; 159--173
    1506-218X
    Pojawia się w:
    Rocznik Ochrona Środowiska
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Collaborative patterns of long-term sustainability in community social enterprises: an international comparative case study
    Autorzy:
    Kovanen, Sunna
    Powiązania:
    https://bibliotekanauki.pl/articles/1050978.pdf
    Data publikacji:
    2020-12-21
    Wydawca:
    Uniwersytet im. Adama Mickiewicza w Poznaniu
    Tematy:
    community enterprise
    long-term sustainability
    community of practice
    case study
    degrowth
    Opis:
    The article presents results from a research on the relevance and challenges of collaboration for the long-term sustainability of rural community enterprises. The study relies on Communities of Practice and Degrowth theories. Methods include semi-standardised interviews and focused ethnography in two community enterprises in rural areas in Germany and Portugal. Main results confirm the relevance of collaborative relations with residents, public sector, peer organisations and within the teams for both stability and transformative power of the organisations’ work. Respectful handling of privileges and balance in participation and professionalisation support sustainability, whereas institutional stagnation and involuntary degrowth may risk it.
    Źródło:
    Quaestiones Geographicae; 2020, 39, 4; 53-63
    0137-477X
    2081-6383
    Pojawia się w:
    Quaestiones Geographicae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Struktura i dynamika wielogeneracyjnych starodrzewów sosnowych występujących w obszarach ochrony ścisłej Kaliszki i Sieraków w Kampinoskim Parku Narodowym. Część 1. Zróżnicowanie gatunkowe, zagęszczenie i pierśnicowe pole przekroju
    Structure and dynamics of uneven−aged Scots pine−dominated old−growth stands in Kaliszki and Sieraków strict protection areas in the Kampinos National Park. Part 1. Species composition, tree density and basal area
    Autorzy:
    Brzeziecki, B.
    Zajączkowski, J.
    Olszewski, A.
    Bolibok, L.
    Andrzejczyk, T.
    Bielak, K.
    Buraczyk, W.
    Drozdowski, S.
    Gawron, L.
    Jastrzębowski, S.
    Szeligowski, H.
    Żybura, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/978936.pdf
    Data publikacji:
    2020
    Wydawca:
    Polskie Towarzystwo Leśne
    Tematy:
    forest dynamics
    long−term research
    old−growth forest
    permanent study plot
    strict protection
    tree
    species composition
    Opis:
    The paper describes changes, which took place over the last 30 years in old−growth forest stands occupying two permanent research plots, established in the Kaliszki and Sieraków strict protection areas in the Kampinos National Park (central Poland). Both plots have a form of ecological transects. The Kaliszki plot is 20 m wide and 700 m long (1.40 ha), while the Sieraków plot (total area of 2.56 ha) consists of two parts: main (40×460 m) and side (40×180 m) transect. In the Kaliszki plot, the stand measurements were conducted in 1993, 2007, and 2017, while in the Sieraków plot – in 1989, 1994, 2006, and 2017. For every tree with breast height diameter (DBH) 5 cm, species identity, DBH and spatial coordinates were determined. Starting from the second census, all trees which had died (‘losses’), as well as trees which exceeded the DBH threshold (‘gains’) since the previous record were noted, as well. The major tree species occurring on sample plots are Scots pine (Pinus sylvestris), pedunculate oak (Quercus robur), silver and downy birch (Betula sp.), and black alder (Alnus glutinosa). During the study period, the overall tree density declined by ca. 50%. The diminishing trends occurred for all dominant tree species. In contrast to major, dominant tree species, the demographic status of a group of minor tree species (lime, hornbeam and maple) was much more stable. One may even speak about some expansion in this case. Particularly, hornbeam density increased rapidly in the period 2006−2017 in some areas of the main transect located in the Sieraków plot. The future studies will show if this tendency will be maintained and will include other regions of sample plots. Assuming a lack of significant disturbances, one may expect that the stands growing on research plots will rather slowly change in the nearest future. Most dynamics will have a quantitative and not qualitative character. One may anticipate, for example, a growing role of pedunculate oak at the expense of Scots pine, however, considering that the two species are rather long−living, they will probably for a long time keep their dominant roles in the stand canopies.
    Źródło:
    Sylwan; 2020, 164, 05; 392-403
    0039-7660
    Pojawia się w:
    Sylwan
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Struktura i dynamika wielogeneracyjnych starodrzewów sosnowych występujących w obszarach ochrony ścisłej Kaliszki i Sieraków w Kampinoskim Parku Narodowym. Część 2. Procesy zamierania i dorastania oraz ich wpływ na rozkład grubości drzew
    Structure and dynamics of uneven−aged, Scots pine−dominated, old−growth stands in Kaliszki and Sieraków strict reserves in Kampinos National Park. Part 2. Tree mortality and recruitment processes and their effects on tree diameter distributions
    Autorzy:
    Brzeziecki, B.
    Zajączkowski, J.
    Olszewski, A.
    Bolibok, L.
    Andrzejczyk, T.
    Bielak, K.
    Buraczyk, W.
    Drozdowski, S.
    Gawron, L.
    Jastrzębowski, S.
    Szeligowski, H.
    Żybura, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/979128.pdf
    Data publikacji:
    2020
    Wydawca:
    Polskie Towarzystwo Leśne
    Tematy:
    demographic non−equilibrium
    diameter structure
    long−term study
    old−growth forest
    permanent study
    plot
    scots pine
    strict protection
    Opis:
    Two fundamental demographic processes (tree recruitment and mortality) are analyzed for forest stands growing on permanent study plots located in strictly protected Scots pine−dominated, old−growth stands of Kampinos National Park (central Poland). The major implications of the observed demographic trends for the general shape of tree size distributions are determined, as well. During the past ca 30 years, in the stands sampled, there was a pronounced lack of balance between mortality and recruitment processes. Mortality rate was eight times higher than recruitment rate. Eventually, there was a net significant decline in population density, observed for all major tree species, including Scots pine, pedunculate oak, silver and downy birch, and black alder. As mortality processes affected mainly smaller trees, there was also a significant deterioration of the general demographic status of most important tree species. This effect was shown by the change of the overall shape of diameter distributions over the study period: from reverse J−shaped to flat curves running nearly parallel to X−axis. The values of recruitment rates were markedly lower, and the values of mortality rates – significantly higher, than analogous values characterizing comparable forests (e.g., those obtained for the natural stands of Białowieża National Park). Low recruitment rates, as obtained for Kampinos stands, suggest that presently, in the local, Scots pine−dominated, old−growth stands, the general conditions for forest regeneration and for maintaining a long−term demographic stability are unfavorable. Most probably, the regeneration of this type of forest has an episodic, ‘wave−like’ character and corresponds to the ‘catastrophic’ model, according to which the successful regeneration of current dominants (especially Scots pine, silver and downy birch, black alder) must be preceded by a stand−initiating (stand−replacing) disturbance, leading to total or partial, but heavy, destruction of the currently existing stand. At the moment, it would be difficult to predict, however, if and when such a disturbance will affect the stands under investigation. Thus, we predict that in the nearest future at least, the state of overall demographic unbalance will continue or even increase.
    Źródło:
    Sylwan; 2020, 164, 06; 443-453
    0039-7660
    Pojawia się w:
    Sylwan
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Odnowienie naturalne drzew w Puszczy Białowieskiej
    Natural regeneration of trees in the Bialowieza Forest
    Autorzy:
    Brzeziecki, B.
    Andrzejczyk, T.
    Żybura, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/985949.pdf
    Data publikacji:
    2018
    Wydawca:
    Polskie Towarzystwo Leśne
    Tematy:
    lesnictwo
    Puszcza Bialowieska
    odnowienia naturalne
    drzewa lesne
    topola osika
    Populus tremula
    brzoza brodawkowata
    Betula pendula
    brzoza omszona
    Betula pubescens
    olsza czarna
    Alnus glutinosa
    sosna zwyczajna
    Pinus sylvestris
    dab szypulkowy
    Quercus robur
    jesion wyniosly
    Fraxinus excelsior
    klon pospolity
    Acer platanoides
    wiaz gorski
    Ulmus glabra
    swierk pospolity
    Picea abies
    lipa drobnolistna
    Tilia cordata
    grab pospolity
    proces dorastania
    ekosystemy lesne
    dynamika lasu
    active approach
    deer browsing
    long−term study
    multifunctional forest management
    natural recruitment
    nature conservation
    silvicultural treatment
    strict protection
    tree competition
    tree diversity
    Opis:
    Since several years already, a massive infestation of bark beetle has taken place in the Białowieża Forest, decimating a local Norway spruce population. In consequence, many open areas appeared, practically deprived of trees and other forest vegetation. The existence of such areas has a very negative impact on multiple values of the Białowieża Forest: natural, social, economical and landscape−aesthetic values. The local forest administration prepared a strategy aimed at active restoration of diverse woodland communities typical for the Białowieża Forest in all places, where bark beetle infestation wiped up the spruce stands. Those plans were criticized by representatives of the environmental organizations who blamed the foresters for transforming the Białowieża Forest into ‘plantation’ and claiming that such measures are inconsistent with the existing forest management and protection plan. The postulate of environmentalists is that the recovery of woodland communities should proceed completely naturally. Taking into account the above mentioned controversies, in this paper we examine the issue of natural regeneration in the Białowieża Forest in detail. In particular, we try to determine to which extent this method of forest reproduction enables re−establishment of compositionally diverse woodland communities, distinguished by a high level of biological diversity and able to provide a wide range of commodities and benefits important for today’s society. Based on an extensive literature review we show that a combination of different (abiotic and biotic) factors, influencing establishment and subsequent growth of seedlings and saplings in the Białowieża Forest has long been strongly unfavorable for many tree species. In this regard, one should particularly emphasize the negative role of large herbivores, especially red deer, which is present in the Białowieża Forest since the end of 19th century, when it became a private hunting ground for Russian tzars. The devastating effect of deer browsing on natural regeneration is a well−documented phenomenon and widely recognized problem in the forestry practice. The fencing of young forest generation against game pressure is an indispensable measure, needed to secure the continuous existence of several tree species (first of all those palatable and vulnerable to browsing). Very strong arguments for an active approach to the described problem delivers also a long−term study on natural forest dynamics conducted since 1936. It shows that under conditions of strict protection the regeneration capacity of the Białowieża tree species is very variable. These differences lead to the compositional simplification and impoverishment of many tree stands, with numerous negative consequences for local biodiversity. We underline that an active management strategy is a basic prerequisite for maintaining a diverse character of the Białowieża stands and their ability to provide all important ecosystem services on a sustainable basis. Such a strategy should include, beside of the phase of establishment, also the subsequent developmental stages of new forest generations. The general goal of such a strategy should be to secure a possibly high diversity of tree composition and to enable the development of tree species representing a full range of life−history strategies and playing different successional roles: from typical pioneer species, through intermediate, to climax species.
    Źródło:
    Sylwan; 2018, 162, 11; 883-896
    0039-7660
    Pojawia się w:
    Sylwan
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Wyniki wstępnych badań nad długookresowym rozwojem krajowego systemu wytwarzania energii elektrycznej w Polsce
    Results of preliminary studies on the long-term development of the power system in Poland
    Autorzy:
    Pluta, M.
    Wyrwa, A.
    Mirowski, T.
    Zyśk, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/282363.pdf
    Data publikacji:
    2012
    Wydawca:
    Polska Akademia Nauk. Instytut Gospodarki Surowcami Mineralnymi i Energią PAN
    Tematy:
    system elektroenergetyczny
    modelowanie matematyczne
    badanie długookresowe
    prognoza do 2050
    National Power System
    mathematical modeling
    long-term study
    forecast to 2050
    Opis:
    W artykule przedstawiono wyniki wstępnych badań nad długookresowym rozwojem Krajowego Systemu Elektroenergetycznego (KSE) w Polsce. W szczególności zbadano wpływ cen uprawnień do emisji CO2 (EUA) wynikających z dwóch scenariuszy Energetycznej Mapy Drogowej 2050 na zmiany w strukturze mocy wytwórczych oraz produkcji w KSE. Głównym narzędziem analitycznym wykorzystanym w pracy był generator modeli systemów energetycznych - TIMES. W artykule zaprezentowano zbudowany i wykorzystany do analizy referencyjny model krajowego systemu wytwarzania energii elektrycznej w Polsce. Przedstawiono podstawowe założenia obliczeniowe obejmujące prognozy: cen i poda nośników energii pierwotnej, cen uprawnień do emisji CO2 zapotrzebowania na energię elektryczną oraz parametrów techniczno-ekonomicznych stosowanych technologii energetycznych. Otrzymane wyniki wskazują na istotne zmiany w strukturze paliwowej i technologicznej KSE do roku 2050 spowodowane polityką dekarbonizacyjną. Zmiany te pogłębia wzrost ceny EUA. Znacząco wzrośnie rola źródeł niskoemisyjnych: odnawialnych, głównie elektrowni wiatrowych i elektrociepłowni opalanych biomasą, elektrowni jądrowych, elektrowni opalanych węglem brunatnym wyposażonych w technologie CCS.
    This paper presents the results of preliminary studies on the long-term development of the power system in Poland. In particular, it analyzes the impact of the price of CO2 emission allowances resulting from the two scenarios of the Energy Roadmap 2050 on the change in the structure of generating capacity and production. The main analytical tool used in the examination was the TIMES model generator. The paper further describes the Reference Energy System developed and used. The main computational assumptions include predictions of the following: prices and supply of primary energy sources, prices of CO2 emission allowances (EUA), the demand for electricity, the technical and economic parameters of energy technologies. The results revealed significant changes in the structure of fuels and technologies up to 2050 caused by the decarbonization policy. These changes deepen with the increase in the EUA price. The role of low carbon technologies such as: renewables, mainly wind turbines and biomass CHPs, nuclear power plants, brown coal power plants equipped with CCS will significantly increase.
    Źródło:
    Polityka Energetyczna; 2012, 15, 4; 85-96
    1429-6675
    Pojawia się w:
    Polityka Energetyczna
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Forest Return on an Abandoned Field – Secondary Succession Under Monitored Conditions
    Autorzy:
    Adamowski, Wojciech
    Bomanowska, Anna
    Powiązania:
    https://bibliotekanauki.pl/articles/764953.pdf
    Data publikacji:
    2011
    Wydawca:
    Uniwersytet Łódzki. Wydawnictwo Uniwersytetu Łódzkiego
    Tematy:
    abandoned field
    long-term study
    permanent plots
    species turnover
    vegetation succession
    Białowieża Forest
    Polska
    Opis:
    The secondary succession pattern observed on an arable field abandoned since 1974 in Tilio-Carpinetum habitat is described and disscussed. Results obtained during 36 years of study confirm that succession on an abandoned field leads from a typical segetal community to the formation of a juvenile treestand composed of pioneer species. Our study supports the view that succession is a process which is largely dependent on the initial conditions and surrounding vegetation. The results indicate that some species can modify the course of this process, accelerating or slowing it down. Limitations of the method and prognosis of future vegetation development are also discussed.
    Źródło:
    Acta Universitatis Lodziensis. Folia Biologica et Oecologica; 2011, 7; 49-73
    1730-2366
    2083-8484
    Pojawia się w:
    Acta Universitatis Lodziensis. Folia Biologica et Oecologica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Wieloletnia dynamika drzewostanów na dawnym zrębie kulisowym w warunkach ochrony ścisłej (Łysica, Góry Świętokrzyskie)
    Long-term dynamics of forest stands on a former narrow strip clear cut under conditions of strict protection (Lysica, the Swietokrzyskie Mountains)
    Autorzy:
    Brzeziecki, B.
    Janicki, S.
    Wiech, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1008894.pdf
    Data publikacji:
    2011
    Wydawca:
    Polskie Towarzystwo Leśne
    Tematy:
    lesnictwo
    parki narodowe
    Swietokrzyski Park Narodowy
    obszary ochrony scislej
    rezerwat Lysica
    stale powierzchnie obserwacyjne
    zrab kulisowy
    drzewostany
    dynamika drzewostanu
    zmiany skladu gatunkowego
    buk zwyczajny
    Fagus sylvatica
    jodla pospolita
    Abies alba
    swierk pospolity
    Picea abies
    klon jawor
    Acer pseudoplatanus
    zageszczenie drzew
    rozwoj drzewostanu
    stand dynamics
    long−term study
    narrow strip clear cut
    european beech
    norway spruce
    silver fir
    sycamore
    strict protection
    Opis:
    Major results of the 45−year−long study on the dynamics of strictly protected forest stands, using 3 permanent study plots, 25×100 m each, located on a former narrow strip clear cut established in the beginning of the 20th century on the northern slopes of the Mt. Łysica (the Świętokrzyskie Mountains, Central Poland) are presented. The general development of forest stands is analysed, including change of overall density, tree mortality rate (general and by species), dynamics of basal area and average tree diameter, competitive ability as well as changing role of particular species (mainly European beech, silver fir, sycamore and Norway spruce) in formation of the general stand structure. The results of the study are compared with other investigations of similar type.
    Źródło:
    Sylwan; 2011, 155, 08; 518-529
    0039-7660
    Pojawia się w:
    Sylwan
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-8 z 8

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