27,504 research outputs found
Explicit stress integration with error control for the Barcelona basic model: part II: algorithms efficiency and accuracy
No full textThe paper compares the accuracy and efficiency of explicit stress integration schemes for elasto-plastic unsaturated soil models with automatic error control. Numerical tests are performed with reference to the Barcelona Basic Model (BBM), one of the most popular elasto-plastic models for unsaturated soils, by using eight explicit Runge–Kutta algorithms of various order as well as a novel application of the extrapolation method described in the companion paper. Initially, the results obtained from the lowest order Runge–Kutta scheme (i.e. Modified Euler) as well as the extrapolation method are checked against accurate solutions of a number of BBM paths involving changes of strains and suction. Subsequently, the efficiency and accuracy of all algorithms are assessed for generic increments of strains and suction, while the difference between two alternative error control methods is also analysed. The results presented, although strictly valid for the Barcelona Basic Model, are expected to be general and relevant to other similar unsaturated elasto-plastic models formulated in terms of two independent stress variables such as net stress and suction
Explicit stress integration with error control for the Barcelona basic model: part I: algorithms formulations
No full textThe numerical integration of the stress–strain relationship is an important part of many finite element code used in geotechnical engineering. The integration of elasto-plastic models for unsaturated soils poses additional challenges associated to the presence of suction as an extra constitutive variable with respect to traditional saturated soil models. In this contribution, a range of explicit stress integration schemes are derived with specific reference to the Barcelona Basic Model (BBM), which is one of the best known elasto-plastic constitutive models for unsaturated soils. These schemes, however, do not address possible non-convexity of the loading collapse (LC) curve and neglect yielding on the suction increase (SI) line. The paper describes eight Runge–Kutta methods of various orders with adaptive substepping as well as a novel integration scheme based on Richardson extrapolation. The algorithms presented also incorporate two alternative error control methods to ensure accuracy of the numerical integration. Extensive validation and comparison of different schemes are presented in a companion paper. Although the algorithms presented were coded for the Barcelona Basic Model, they can be easily adapted to other unsaturated elasto-plastic models formulated in terms of two independent stress variables such as net stress and suction
A constitutive framework for the chemo-mechanical behaviour of unsaturated non-expansive clays
No full textBoth osmotic and matric suction changes have a significant influence on the mechanical behaviour of clays. Despite the different types of interactions at the microstructural level, both suctions havea relevant effect on the fabric of non-expansive clays. Starting from experimental observations at the laboratory scale, it is possible to identify some common features characterizing the mechanical response of non-expansive clays to salinity and degree of saturation changes. This paper presents an elastoplasticframework to reproduce the behaviour of unsaturated clayey soils upon changes in the salt concentration of the pore fluid. In particular, it presents a strategy to include osmotic suction induced by pore fluid salinity in BBM-like models [1]. The model was implemented in the Thebes code and it was calibrated on experimental data performed on Boom clay [2] and remoulded loess [3]
Author neologisms in the novel "Rzeczy uprzyjemniające. Utopia" by T. Boldak-Janovska
No full textThe purpose of this article is an analysis of author neologisms extracted from the novel "Rzeczy uprzyjemniające. Utopia" by T. Boldak-Janovska – writer, although living in Olsztyn, belonging to the Polish-Belarusian border. The object of research was elected not by accident: for a few years the novel attracts the attention of readers and critics. For the purposes of this analysis were selected 186 neologisms, mostly nouns and verbs, most of whom are motivated formations. The most numerous are the names of animals, birds, reptile and fish, names of plants, trees, shrubs, names of everyday objects. Author neologisms constitute an indispensable component of the Polish vocabulary. They are understandable for the users through the context and through the semantic link to the radial network to which they [email protected]. Bołdak-Janowska, 2009, Rzeczy uprzyjemniające. Utopia, Olsztyn.Buttler D., 1962, Neologizm i terminy pokrewne, „Poradnik Językowy” nr 5, s. 239–244.Bołdak-Janowska T., 2012, Szkic na Trialog 2012, „Jak daleko stąd, jak blisko”, czyli gdzie?, http://issuu.com/tamarabejot/docs/jak daleko/1, online, [8.10.
2014].Chłosta-Zielonka J., 2013, Najnowsza proza olsztyńskich twórców. Rekonesans, „Prace Literaturoznawcze UniwersytetuWarmińsko-Mazurskiego” t. 1, Olsztyn, s. 229–239.Jadacka H., 2001, System słowotwórczy polszczyzny (1945–2000), Warszawa.Kwietniowa W., 1973, O neologizmach stylu artystycznego, „Polonistyka” nr 5, s. 9–17. Polska Biografia Literacka PAN, 2012, www.pbl.ibl.poznan.pl, online, [8.10.2014]Sękowska E., 2012, Neologizmy słowotwórcze we współczesnej polszczyźnie (wybrane tendencje), [w:] Eslavistica Complutense, Warszawa, s. 97–103.Skubalanka T., 1990, Problematyka gramatyczno-stylistyczna neologizmu, „Studia Linguistica Polono-Slovaca” nr 3, s. 31–37.Smółkowa T., 1997,Metodologiczne aspekty opisu współczesnych neologizmów i neosemantyzmów polskich, [w:] Leksyka słowiańska na warsztacie językoznawcy, red. H. Popowska-Taborska, Warszawa.Smółkowa T., 2001, Neologizmy we współczesnej leksyce polskiej, Kraków.Waszakowa K., 1998, Neologizmy tekstowe w świetle ram interpretacyjnych, [w:] Tekst. Analizy i interpretacje, Lublin, s. 21–33.Waszakowa K., 2007, Wariantywne postaci neologizmów w świetle adaptacyjnej funkcji słowotwórstwa, „Prace Filologiczne Uniwersytetu Warszawskiego” t. LIII, Warszawa, s. 691–700.299-31
Modelling the behaviour of unsaturated non-active clays in saline environment
No full textThe chemical composition of pore fluid and matric suction rule the mechanical behaviour of soils. In case of clays, their fabric changes in line with those variables. Since both the increase in matric suction and salinity cause a transition from an open to a close microstructure of low and medium activity clayey materials, a unique framework could tackle problems where salinity and saturation changes are expected. This paper presents a simple elasto-plastic model capable of reproducing the behaviour of unsaturated clayey soils in saline environments. Changes in the pore fluid composition are addressed through the use of osmotic suction as a variable. The proposed model extends the Barcelona Basic Model for partially saturated soils to consider the effect of osmotic suction. The model, implemented in the Thebes code, is calibrated for Boom Clay. The reproduced tests include mechanical loading at different matric and osmotic suctions in oedometric conditions, as well as more complex chemo-mechanical stress paths. Despite the simplicity of the formulation, the agreement between the experimental results and the simulations is encouraging. It seems that the modelling approach addresses the most important features of partially saturated soils with saline pore fluid which are slightly or moderately expansive
Letter to W. T. Shaw concerning W. T. Chapman
No full textLetter written to W. T. Shaw by an unknown author with W. T. Chapman as the subjec
Bishop W. T. Handy Jr., circa 1991
No full textPortrait of Bishop W. T. Handy Jr. Written on verso: Board Chair Bishop W. T. Handy Jr. April 6, 1990 - April 16, 1993.The Atlanta University Center Robert W. Woodruff Library acknowledges the generous support of the National Endowment for Humanities - Humanities Collections and Reference Resources Implementation Project Grant in supporting the processing and digitization of a number of its major archival collections as part of the project: Spreading the Word: Expanding Access to African American Religious Archival Collections at the Atlanta University Center Robert W. Woodruff Library.</em
Zagadnienia stabilności zatrudnienia na stanowisku pierwszego trenera w polskich klubach piłkarskich
No full textArtykuł dotyczy zjawiska zatrudniania i zwalniania trenerów w polskich klubach
piłkarskich. Odnosi się do wpływu tych zmian na modyfikację strategii działania klubów
i ich efektywność w podstawowych aspektach ich działalności. Autor oparł się na
wynikach badań prowadzonych w ramach pracy nad rozprawą doktorską dotyczącą
uwarunkowań efektywnego funkcjonowania zespołów sportowych. Tezy zawarte w
tekście opierają się zarówno na badaniach (wywiadach eksperckich) przeprowadzonych
wśród polskich trenerów piłkarskich pracujących w ekstraklasie, jak i obserwacjach
funkcjonowania polskich klubów piłkarskich. W tekście zawarto rozważania dotyczące
miejsca trenera w strukturze organizacyjnej klubu sportowego, jego wpływu na wyniki
organizacji. Przeprowadzono także analizę zjawiska zmian na stanowisku pierwszego
trenera w klubach polskiej ekstraklasy w rundzie jesiennej sezonu 2010/2011. W ramach
tekstu dokonano próby uchwycenia potencjalnego wpływu tych zmian na wyniki
zespołów sportowych, które są kluczowym elementem klubu sportowego wpływającym
na jego efektywność. Autor podjął także próbę ustalenia wpływu niestabilności
zatrudnienia na stanowisku pierwszego trenera na niezadowalające wyniki osiągane
przez polskie kluby na arenie międzynarodowej. Artykuł służy prezentacji wyników
badań i rozważań autora w ramach tej tematyki.The subject of the article is frequent changes of team managers in polish football clubs. The author shows the influence of team manager rotation on overall performance of sports organizations. Given the growing importance of sports in polish bussiness world, and amounts of funds invested, sports need a professional approach by managers. Team manager plays a key role in sports organization, and effectiveness of the team led by him influences the organization as a whole. The text is based on the reasearch done by the author in process of preparing doctorate thesis about effectiveness of sports teams. The reasearch was done both by interviewing polish team managers from top league, and by observations done in polish sports clubs. First part of the article focuses on placing the manager in organizational structure of a sports club, and his role in managing those organizations. Author also analyzed the changes made in polish teams in 2010/2011 season of polish ekstraklasa. The potential influence on teams performance is the subject of the last part of an article. The author tries to find connection between sport clubs policy regarding managers, and their poor performance in the european cups. The article shows the outcome of the reasearch done by the author, and gives personal conclusions on the subject, based on knowledge and experience gained during the process of preparing doctorate thesis
Letter from Secretary to W. W. Bass
No full textLetter to W. W. Bass from Carl Hayden's secretary informing him of a vote on the national park bill will not be held until December
An Elastoplastic Framework Accounting for Changes in Matric and Osmotic Suction in Unsaturated Non-expansive Clays
No full textThe mechanical behaviour of clays is significantly influenced by their salinity and degree of saturation, which are expected to change in both natural and anthropogenic environments. This influence is triggered by fabric changes. Capillary forces, related to changes in the degree of saturation, and electrochemical interactions, related to changes in salinity, affect differently the interaction between particles. However, at the continuum scale, it is possible to pinpoint some common characteristics. This paper focuses on the modelling capabilities of an elasto-plastic framework formulated to reproduce the behaviour of unsaturated non-expansive clays exposed to changes in matric and osmotic suction, by introducing osmotic suction on BBM-like models in terms of its effects on the normal compression line. The model, calibrated on experimental data on Boom clay (Mokni et al., 2014) and remoulded loess (Zhang et al., 2022), has been implemented in the Thebes code and used to predict material response under selected chemo-hydro-mechanical paths
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