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    Tytuł:
    Relationship between van Genuchtens parameters of the retention curve equation and physical properties of soil solid phase
    Autorzy:
    Porebska, D.
    Slawinski, C.
    Lamorski, K.
    Walczak, R.T.
    Powiązania:
    https://bibliotekanauki.pl/articles/24404.pdf
    Data publikacji:
    2006
    Wydawca:
    Polska Akademia Nauk. Instytut Agrofizyki PAN
    Tematy:
    pedotransfer function
    van Genuchten parameter
    soil water
    relationship
    retention curve equation
    physical property
    soil
    water retention curve
    water stress
    plant
    Źródło:
    International Agrophysics; 2006, 20, 2
    0236-8722
    Pojawia się w:
    International Agrophysics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Hysteresis between wetting and drying processes as affected by soil aggregate size
    Autorzy:
    Witkowska-Walczak, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/25257.pdf
    Data publikacji:
    2006
    Wydawca:
    Polska Akademia Nauk. Instytut Agrofizyki PAN
    Tematy:
    soil aggregation
    hysteresis
    soil
    water retention curve
    water retention
    drying process
    wetting process
    Źródło:
    International Agrophysics; 2006, 20, 4
    0236-8722
    Pojawia się w:
    International Agrophysics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Time of soil water thermodynamic equilibrium during retention curve establishment using gamma-ray beam attenuation
    Autorzy:
    Pires, L.
    Bacchi, O.
    Reichardt, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/148674.pdf
    Data publikacji:
    2005
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    gamma-ray attenuation
    time of equilibrium
    pressure chamber
    soil water retention curve
    Opis:
    The soil water retention curve (SWRC) represents a fundamental part of the characterization of the soil hydraulic properties. The establishment of SWRC is usually time-consuming and presents several problems such as the difficulty of a correct judgment of the time of equilibrium. This work presents a new methodology that involves gammaray beam attenuation technique associated with the traditional pressure chambers, having as objective the more precise judgment of the time to attain equilibrium. The gamma-ray source used has an activity of 3.7 GBq consisting of 241Am, with peak energy of 59.54 keV. For the determination of retention curves using the gamma-ray attenuation technique, an acrylic pressure chamber was projected and constructed to be positioned between the source and detector with the gamma-ray beam crossing the center of the chamber and the soil sample during water extraction. The proposed technique allowed, through a specifically elaborated software for data acquisition, to evaluate with precision the exact instant of the equilibrium and, consequently, to obtain the right moment to change the chamber pressure to a new desired level, leading to a reduction of the time required for the whole retention curve determination. The results obtained show that the gamma-ray attenuation technique can be very useful as an auxiliary tool to evaluate SWRC, utilizing the Richards chamber.
    Źródło:
    Nukleonika; 2005, 50, 4; 173-177
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Proposal of concept for structural modelling of hybrid beams
    Autorzy:
    Kożuch, Maciej
    Skrętkowicz, Łukasz
    Powiązania:
    https://bibliotekanauki.pl/articles/2172884.pdf
    Data publikacji:
    2022
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    sand
    mean grain size
    mean pore size model
    pore size distribution
    water retention curve
    Opis:
    Investigation on the behaviour of a hybrid beam is presented. Hybrid beam stands for an element with hybrid cross sections. This means sections that consist of steel and concrete parts, connected together with composite dowels, and both are considered for shear flow analysis. In practice, a more general solution may be used for bridges in the form of a beam in which the span sections are hybrid and the support sections are concrete. Recently such a solution has been introduced for bridge engineering in Poland and a new problem with performing a global analysis of hybrid beams was identified. The solution is new itself and requires also a new approach for internal forces determination. Discussion of this problem is made in the paper. Influences of (1) concrete cracking, (2) rheology of concrete and (3) methods of modelling on the redistribution of internal forces are highlighted. On an example of one of the real bridge girder (being currently under design) analysis is made to show how the abovementioned factors are affecting obtained results. Results are analysed and conclusions are presented. As a final step, a new concept of hybrid beam design is proposed. The proposed solution enables a quick and easy engineering approach to perform a static calculation of the considered structure.
    Źródło:
    Studia Geotechnica et Mechanica; 2022, 44, 4; 317--332
    0137-6365
    2083-831X
    Pojawia się w:
    Studia Geotechnica et Mechanica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Impact of marble powder amendment on hydraulic properties of a sandy soil
    Autorzy:
    Farhadi-Machekposhti, M.
    Valdes-Abellan, J.
    Pla, C.
    Benavente, D.
    Pachepsky, Y.
    Powiązania:
    https://bibliotekanauki.pl/articles/2082885.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Instytut Agrofizyki PAN
    Tematy:
    saturated hydraulic conductivity
    soil water
    retention curve
    field capacity
    plant available water
    pore size
    distribution
    Opis:
    Marble powder is one of carbonate rock amendments that is used to improve soil reaction. We hypothesized that the powdered marble addition can cause favorable changes in hydraulic properties of sandy soils. Six levels of marble powder addition to an aridisol soil (0%; M0; 5%; M5; 10%; M10; 15%; M15; 20%; M20 and 25%, M25; by bulk volume) were analyzed in triplicate. The saturated hydraulic conductivity and soil water retention curves were obtained. Pore space properties were investigated using soil water retention curves, mercury intrusion porosimetry and scanning electron microscopy. The saturated hydraulic conductivity significantly decreased (between 83 and 97% for M5 and M25 respectively) and parameters α and n of the van Genuchten model significantly decreased in marble-amended soils. Both field capacity and permanent wilting point increased with the addition of marble powder. Plant-available water, increased significantly until 10% of marble powder application; higher percentages of application did not provide additional significant changes in the plant-available water. Pore space distributions from soil water retention curves parameters showed an increase in the pore size range and a decrease in the average pore size; pore space distribution from the scanning electron microscopy also showed the presence of a new family of dominant pore sizes which was not detected by the soil water retention curves parameters approach. It was concluded that the addition of marble powder can improve the ability of soil to store water providing an advantage for irrigation water management in water scarce environments. Further research will have to address the impact of marble powder amendment under field semi-arid conditions.
    Źródło:
    International Agrophysics; 2020, 34, 2; 223-232
    0236-8722
    Pojawia się w:
    International Agrophysics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    An analytical model to predict water retention curves for granular materials using the grain-size distribution curve
    Autorzy:
    Bouacida, Linda
    Feia, Sadok
    Denine, Sid Ali
    Della, Noureddine
    Powiązania:
    https://bibliotekanauki.pl/articles/2172891.pdf
    Data publikacji:
    2022
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    sand
    mean grain size
    mean pore size
    density index
    model
    pore size distribution
    water retention curve
    Opis:
    The present work aims to propose a new analytical model intended to predict the water retention curves for granular materials based on data from tensiometric tests. Different analytical models have been used for the evaluation of soil water retention curves so far. It should be noted that the proposed model considers only one criterion in the selection of soils. This criterion is the physical property of particle distribution curve that can be used to determine the values of D50 and CU. In this study, the pore-access size distribution is investigated considering the effect of the coefficient of uniformity of sandy soils that were prepared with different density indexes (0.5, 0.7, and 0.9). Moreover, the proposed model equation is based on the physical properties of soil. This equation made it possible to describe the water retention curve and to estimate the pore-access size distribution without performing any experimental tests. The findings allowed asserting that the uniformity of the particle size curves corresponds to a good uniformity of the pore-access size distribution. In addition, it was revealed that the suction increased as the density index went up, which matches well with the experimental data. Moreover, it may clearly be noted that the distinctive retention properties of unsaturated soils can be observed on the above-mentioned curves. Further, it was found that the ratio of the grain size over the pore-access size increased as the uniformity coefficient augmented.
    Źródło:
    Studia Geotechnica et Mechanica; 2022, 44, 4; 354--369
    0137-6365
    2083-831X
    Pojawia się w:
    Studia Geotechnica et Mechanica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Wyznaczanie krzywej retencji wody materiałów porowatych za pomocą sond psychometrycznych i TDR
    Determination of the water retention curves for porous materials using psychrometric probes combined with TDR methodology
    Autorzy:
    Guz, Ł.
    Suchorab, Z.
    Alcobia, B.
    Sobczuk, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/126951.pdf
    Data publikacji:
    2010
    Wydawca:
    Towarzystwo Chemii i Inżynierii Ekologicznej
    Tematy:
    psychrometria
    sonda TDR
    krzywa retencji
    materiały porowate
    psychrometric probe
    TDR probe
    soil water retention curve
    porous materials
    Opis:
    Woda jest bardzo ważnym składnikiem produkcji materiałów budowlanych. Jest również jednym z najbardziej destruktywnych czynników podczas późniejszej eksploatacji obiektów z nich zbudowanych. Z tego względu niezbędna jest znajomość właściwości wilgotnościowych materiałów, takich jak: podsiąkanie kapilarne, opór dyfuzyjny czy nasiąkliwość. Właściwości materiałów porowatych związanych z wilgotnością bardzo dobrze opisuje krzywa retencji wody. Określa ona, jaką ilość wody materiał porowaty jest w stanie wchłonąć oraz z jaką siłą utrzymuje wodę w przestrzeniach porowatych. Jest to zależność pomiędzy ciśnieniem ssącym wodę a zawartością wody. W niniejszej pracy przedstawiono krzywe retencji wody wyznaczone dla gazobetonu o gęstości 450; 550 i 650 kg/m3. Krzywa została wyznaczona poprzez sprzężenie dwóch technik pomiarowych: psychrometrycznej i reflektometrycznej TDR. Ciśnienie ssące było zmierzone za pomocą sond psychrometrycznych Peltiera, a wilgotność objętościowa poprzez sondy TDR. Krzywa retencji opisana w publikacji została wyznaczona tylko w wąskim zakresie, determinowanym czułością sond psychrometrycznych, który mieścił się w granicach od 0,03 do 0,12 m3/m3 wilgotności objętościowej materiału porowatego.
    Water is an important compound of building materials production technology. On the other hand it is one of the most destructive factor during exploitation of building objects. That is why it is necessary to know the moisture parameters of the materials like porosity, maximum water content, capillary rise and water conductivity. Water parameters of the porous materials can be described by water retention curve, which valuates what amount of water can be absorbed by the material and what force remains water in air gaps. It is dependence between water potential and moisture. In this work there are presented water retention curves determined for aerated concrete with the apparent density of 450, 550 and 650 kg/m3. Determination of water retention curve was achieved by combination of two measuring techniques: Peltier psychrometric probes for water potential and TDR for water content. Water retention curve described in the paper was established only in a small range of moisture which is mainly caused by the sensitivity of the psychrometric probes, which value was varying in the frames of material moisture between 0.03 and 0.12 m3/m3.
    Źródło:
    Proceedings of ECOpole; 2010, 4, 2; 371-375
    1898-617X
    2084-4557
    Pojawia się w:
    Proceedings of ECOpole
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Wplyw geometrii probki na krzywa retencji wodnej gleby - badania modelowe
    Autorzy:
    Czachor, H
    Powiązania:
    https://bibliotekanauki.pl/articles/1401810.pdf
    Data publikacji:
    2000
    Wydawca:
    Polska Akademia Nauk. Instytut Agrofizyki PAN
    Tematy:
    gleby
    wilgotnosc gleby
    retencja wodna
    krzywa retencji wodnej
    sklad granulometryczny
    osrodki granularne
    sklad chemiczny
    potencjal wodny
    badania modelowe
    soil
    soil moisture
    water retention
    water retention curve
    granulometric composition
    granular medium
    chemical composition
    water potential
    model research
    Opis:
    Przedstawiono wyniki symulacji osuszania wirtualnego trójwymiarowego ośrodka granularnego. Wynika z nich, że zależność wilgotność - potencjał macierzysty gleby powinna zależeć od geometrii próbki rozumianej jako stosunek objętości do tej części powierzchni zewnętrznej przez którą próbka kontaktuje się z otoczeniem.
    The virtual 3D virtual grain medium was created and than divided on to a set of individual pores by means of the 3D tessellation procedure. Volumes of all pores and capillary pressure of all necks have been calculated. Simulation of drainage shows that moisture relenlion curve of virtual medium depends on soil sample geometry, i.e. the ratio of volume and surface connected with the atmosphere.
    Źródło:
    Acta Agrophysica; 2000, 38; 289-301
    1234-4125
    Pojawia się w:
    Acta Agrophysica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Wykorzystanie analizy kohortowej do badania procesów retencji zatrudnienia
    Use of Cohort Analysis in Study of Retention Processes
    Autorzy:
    Spyrka, Sandra
    Powiązania:
    https://bibliotekanauki.pl/articles/1195944.pdf
    Data publikacji:
    2012
    Wydawca:
    Szkoła Główna Handlowa w Warszawie
    Tematy:
    cohort
    cohort analysis
    retention
    employee liquidity
    survival curve
    Opis:
    This article presents a cohort analysis as a great tool to examine and to form the employees’ retention processes. The presented study confirmed that the company should pay particular attention to the processes associated with the selection of staff, i.e. to the recruitment and to the selection, but also it should examine the reasons why employees leave the organization, so that they can prevent it, especially in cases where human capital is crucial for the company.
    Źródło:
    Edukacja Ekonomistów i Menedżerów; 2012, 23, 1; 128-137
    1734-087X
    Pojawia się w:
    Edukacja Ekonomistów i Menedżerów
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Using the step linear regression at the analysis of hydrological conditions of the Frysavka drainage basin
    Autorzy:
    Masicek, T.
    Toman, F.
    Palat, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/60472.pdf
    Data publikacji:
    2011
    Wydawca:
    Polska Akademia Nauk. Stowarzyszenie Infrastruktura i Ekologia Terenów Wiejskich PAN
    Tematy:
    runoff curve number
    correlation index
    landscape cover
    DesQ–MAXQ model
    run-off
    regression analysis
    correlation analysis
    retention
    hydrological condition
    drainage
    Frysavka basin
    statistical analysis
    Opis:
    Problems of the retention capacity of the landscape and related runoff conditions are at present, at the time of the occurrence of frequent storm floods, a topical problem. Our research was aimed at the evaluation of effects of physical-geographical factors on hydrological conditions of the Fryšávka River drainage area occurring in the southern part of the Žďárské vrchy CHKO (Žďárské Hills Protected Landscape Area) depending on the current position of the landscape cover. Preparation and analyses of source data were carried out in ArcGIS 9.2 in the ArcView software product by means of the set of integrated software applications ArcMap, ArcCatalog and ArcToolbox. To determine hydrological conditions at the absence of hydrometric observations a method was used of numbers of runoff curves CN in a modification of the DesQ-MAXQ deterministic episode model. Based on hydrological characteristics, potential retention was monitored as well as the volume of flood wave, concentration time and peak discharge. Hydrological modelling was carried out on a design storm precipitation with the return period of 100 years. The significance of physical-geographical factors affecting the landscape retention capacity and runoff conditions was quantified by the statistical method of multiple regression and correlation analysis on the set of 95 partial drainage areas of the studied region. The analyses were carried out using the UNISTAT system. The method makes possible to select independent variables by gradual steps from most important down to least important. Finally, using the step linear regression, a certain number of independent variables was selected mostly affecting the size of a respective dependent variable together with the quantification of their operation through regression coefficients. Results achieved could be used at the implementation of preventive measures resulting in increasing the retention capacity of partial drainage areas, which served for the registration of major runoffs from a unit area.
    Źródło:
    Infrastruktura i Ekologia Terenów Wiejskich; 2011, 11
    1732-5587
    Pojawia się w:
    Infrastruktura i Ekologia Terenów Wiejskich
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-10 z 10

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