Least Squares Estimation Principle and its Geometrical Interpretation

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A comparative study of Young's modulus of single-walled carbon nanotube by CPMD, MD, and first principle simulations

Carbon nanotubes (CNTs), due to their exceptional magnetic, electrical and mechanical properties, are promising candidates for several technical applications ranging from nanoelectronic devices to composites. Young's modulus holds the special status in material properties and micro/nano-electromechanical systems (MEMS/NEMS) design. The excellently regular structures of CNTs facilitate accurate simulation of CNTs' behavior by applying a variety of theoretical methods. Here, three representative numerical methods, i.e., Car-Parrinello molecular dynamics (CPMD), density functional theory (DFT) and molecular dynamics (MD), were applied to calculate Young's modulus of single-walled carbon nanotube (SWCNT) with chirality (3,3). The comparative studies showed that the most accurate result is offered by time consuming DFT simulation. MID simulation produced a less accurate result due to neglecting electronic motions. Compared to the two preceding methods the best performance, with a balance between efficiency and precision, was deduced by CPMD.

Adsorption of formaldehyde molecule on the intrinsic and Al-doped graphene: a first principle study

To search for a high sensitivity sensor for formaldehyde (H2CO), We investigated the adsorption of H2CO on the intrinsic and Al-doped graphene sheets using density functional theory (DFT) calculations. Compared with the intrinsic graphene, the Al-doped graphene system has high binding energy value and short connecting distance, which are caused by the chemisorption of H2CO molecule. Furthermore, the density of states (DOS) results show that orbital hybridization could be seen between H2CO and Al-doped graphene sheet, while there is no evidence for hybridization between the H2CO molecule and the intrinsic graphene sheet. Therefore, Al-doped graphene is expected to be a novel chemical sensor for H2CO gas. We hope our calculations are useful for the application of graphene in chemical sensor.

Work and energy equations and the principle of generalized effective stress for unsaturated soils

The effective stress principle has been efficiently applied to saturated soils in the soil mechanics and geotechnical engineering practice; however, its applicability to unsaturated soils is still under debate. The appropriate selection of stress state variables is essential for the construction of constitutive models for unsaturated soils. Owing to the complexity of unsaturated soils, it is difficult to determine the deformation and strength behaviors of unsaturated soils uniquely with the previous single-effective-stress variable theory and two-effective-stress-variable theory in all the situations. In this paper, based on the porous media theory, the specific expression of work is proposed, and the effective stress of unsaturated soils conjugated with the displacement of the soil skeleton is further derived. In the derived work and energy balance equations, the energy dissipation in unsaturated soils is taken into account. According to the derived work and energy balance equations, all of the three generalized stresses and the conjugated strains have effects on the deformation of unsaturated soils. For considering these effects, a principle of generalized effective stress to describe the behaviors of unsaturated soils is proposed. The proposed principle of generalized effective stress may reduce to the previous effective stress theory of single-stress variable or the two-stress variables under certain conditions. This principle provides a helpful reference for the development of constitutive models for unsaturated soils.

The Equivalency Principle for Discounting the Value of Natural Assets: An Application to an Investment Project in the Basque Coast

25 p.

Smooth sets for borel equivalence relations and the covering property for σ-ideals of compact sets

This thesis is divided into three chapters. In the first chapter we study the smooth sets with respect to a Borel equivalence realtion E on a Polish space X. The collection of smooth sets forms σ-ideal. We think of smooth sets as analogs of countable sets and we show that an analog of the perfect set theorem for Σ¹₁ sets holds in the context of smooth sets. We also show that the collection of Σ¹₁ smooth sets is ∏¹₁ on the codes. The analogs of thin sets are called sparse sets. We prove that there is a largest ∏¹₁ sparse set and we give a characterization of it. We show that in L there is a ∏¹₁ sparse set which is not smooth. These results are analogs of the results known for the ideal of countable sets, but it remains open to determine if large cardinal axioms imply that ∏¹₁ sparse sets are smooth. Some more specific results are proved for the case of a countable Borel equivalence relation. We also study I(E), the σ-ideal of closed E-smooth sets. Among other things we prove that E is smooth iff I(E) is Borel.

In chapter 2 we study σ-ideals of compact sets. We are interested in the relationship between some descriptive set theoretic properties like thinness, strong calibration and the covering property. We also study products of σ-ideals from the same point of view. In chapter 3 we show that if a σ-ideal I has the covering property (which is an abstract version of the perfect set theorem for Σ¹₁ sets), then there is a largest ∏¹₁ set in I^int (i.e., every closed subset of it is in I). For σ-ideals on 2^ω we present a characterization of this set in a similar way as for C₁, the largest thin ∏¹₁ set. As a corollary we get that if there are only countable many reals in L, then the covering property holds for Σ¹₂ sets.

Optimisation of the first principle code Octopus for massive parallel architectures: application to light harvesting complexes

150 p.

Spin squeezing, macrorealism and the heisenberg uncertainty principle

169 p.

O contrato preliminar incompleto

Esta dissertação tem por objetivo analisar o contrato preliminar, a partir das diversas funções que ele cumpre no processo de formação do negócio jurídico. Em especial, examina-se a figura do contrato preliminar que é menos completo do que o contrato definitivo, estabelecendo apenas os aspectos essenciais do negócio prometido e deixando em aberto outros pontos que devem ser preenchidos no intervalo entre os dois negócios. O contrato preliminar incompleto, como se lhe designa aqui, constitui uma etapa no processo de formação progressiva do contrato, atendendo a interesses dignos de tutela conforme o ordenamento jurídico. Para tanto, o trabalho está dividido em quatro capítulos, além da introdução e da conclusão. Na primeira parte, apresentam-se os principais interesses práticos que estão por trás da cisão do negócio em duas etapas (no contrato preliminar e no contrato definitivo). Vê-se que o contrato preliminar não é uma figura inútil, um desdobramento desnecessário do processo de formação do negócio. Na segunda parte, são delineados os contornos do contrato preliminar, mediante o exame de sua causa e de seu objeto, além das figuras que se lhe assemelham. Demonstra-se que, embora não se confunda com o negócio definitivo, o contrato preliminar já deve definir a causa do negócio prometido, que serve para identificá-lo. Na terceira parte, atenta-se para o chamado princípio da equiparação, que determina que, em regra, o contrato preliminar siga a mesma disciplina prevista para o negócio definitivo. Tal princípio deve ser, todavia, excepcionado, quando a própria cisão do processo de formação do negócio no preliminar e no definitivo serve para afastar alguma regra que valerá apenas para o segundo negócio. Nesse ponto, demonstra-se que o princípio da equiparação não se aplica integralmente no que se refere ao objeto do contrato definitivo, que não precisa estar previsto, exaustivamente, no contrato preliminar. Revela-se, aí, a admissibilidade da figura do contrato preliminar incompleto. Por fim, na última parte, examina-se a execução específica do preliminar, destacando-se, em particular, o cabimento desse remédio também para o chamado contrato preliminar incompleto, quando, então, caberá ao juiz integrá-lo mediante as regras de integração previstas no ordenamento jurídico.

A prior for steepness in stock-recruitment relationships, based on an evolutionary persistence principle

Priors are existing information or beliefs that are needed in Bayesian analysis. Informative priors are important in obtaining the Bayesian posterior distributions for estimated parameters in stock assessment. In the case of the steepness parameter (h), the need for an informative prior is particularly important because it determines the stock-recruitment relationships in the model. However, specifications of the priors for the h parameter are often subjective. We used a simple population model to derive h priors based on life history considerations. The model was based on the evolutionary principle that persistence of any species, given its life history (i.e., natural mortality rate) and its exposure to recruitment variability, requires a minimum recruitment compensation that enables the species to rebound consistently from low critical abundances (Nc). Using the model, we derived the prior probability distributions of the h parameter for fish species that have a range of natural mortality, recruitment variabilities, and Nt values.