1,720,964 research outputs found
Engel condition on enveloping algebras of Lie superalgebras
No full textLet L be a Lie superalgebra over a field of characteristic p≠2 with enveloping algebra U(L) or let L be a restricted Lie superalgebra over a field of characteristic p>2 with restricted enveloping algebra u(L). In this note, we establish when u(L) or U(L) is bounded Lie Engel
Enveloping algebras that are principal ideal rings
No full textLet L be a restricted Lie algebra over a field of positive characteristic. We prove that the restricted enveloping algebra of L is a principal ideal ring if and only if L is an extension of a finite-dimensional torus by a cyclic restricted Lie algebra
Lie Properties of Restricted Enveloping Algebras
No full textLet L be a restricted Lie algebra over a field of positive characteristic. We survey the known results about the Lie structure of the restricted
enveloping algebra u(L) of L. Related results about the structure of the group of units and the symmetric and skew-symmetric elements of u(L) are also discussed. Moreover, a new theorem about an upper bound for the Lie nilpotency class of u(L) is proved
Fox-type problems in enveloping algebras
No full textAbstractLet L be a Lie algebra with the universal enveloping algebra U(L). The augmentation ideal ω(L) of U(L) is the associative ideal of U(L) generated by L. Let S be a subalgebra of L and n a positive integer. In this paper we prove that L∩ω2(L)ωn(S)=γn+2(S)+γn+1(S∩γ2(L)), where γn+2(S) is the (n+2)-th term of the lower central series of S
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
New perspectives on gas adsorption and diffusion in solid porous systems: integrating numerical modeling and machine learning
No full textThe escalating levels of atmospheric CO₂ necessitate efficient and sustainable solutions for its
capture and sequestration. This thesis investigates the theoretical and practical aspects of gas
diffusion and adsorption in KOH-treated activated carbon and Biomass Waste Derived Porous
Carbon, employing advanced mathematical modeling and machine learning techniques. The
objective is to contribute to the development of sustainable technologies to mitigate climate change
impacts. In this work, we correlate diffusivity with the uptake rate and physical properties of both
gas and solid phases, integrating these factors into the governing diffusion equations. Through
an extended Fick’s Law model, we develop a new mathematical framework that predicts gas
adsorption behaviors under diverse operational and thermodynamic conditions. This model is
validated against experimental data across various adsorbents, demonstrating excellent alignment
with real-world adsorption rates, particularly for KOH-treated activated carbons. The high
accuracy of this model underscores its robustness and reliability in predicting adsorption dynamics.
To further enhance predictive accuracy and computational efficiency, advanced machine learning
models including GBR, DNN, CNN, and DWNN are applied. Trained on extensive datasets of CO₂
adsorption characteristics, these models outperform traditional approaches and identify the critical
features influencing adsorption, such as surface area and carbon-to-pressure ratios, which are
essential for optimizing gas adsorption systems. Our findings illustrate the potential of combining
theoretical modeling with machine learning to improve the design, operation, and optimization of
gas adsorption and separation processes, such as CO2 capture and natural gas processing. This
work contributes significantly to the advancement of scalable, efficient gas separation technologies,
paving the way for sustainable solutions in climate change mitigation and resource management.Includes bibliographical references (pages 108-121
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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