Joint inversion of magnetotelluric and seismic data for crustal characterization

Tese de doutoramento, Ciências Geofísicas e da Geoinformação (Geofisíca), Universidade de Lisboa, Faculdade de Ciências, 2014The research that has been performed in this thesis contributes to integration two different geophysical methods (magnetotellurics and seismic refraction). Pattern recognition has not been used for the cooperative inversion of these two methods before. This study demonstrates potential of soft clustering methods for integration of two data sets. Gathering information from both inversions, a multiparameter model was made. This multi-parameter model contains regions, each of which is characterized by a consistent relationship between the model parameters. Both synthetic and field data results were used to discuss an assumption that mutual exchange of information can lead to better results of inversions in both cases. The method developed in this thesis was successfully applied at experimental data collected in the Iberian Pyrite Belt.A investigação desenvolvida nesta tese é uma contribuição para a integração de dois métodos geofísicos (magneto-telúrico e sísmica de refracção). A técnica de reconhecimento de padrões não tinha sido ainda utilizada na inversão cooperativa de dados destes dois métodos. Este estudo mostra as potencialidades dos métodos de análise de “clusters” na integração dos dois conjuntos de dados.Um modelo “multi-parâmetros” foi desenvolvido para extrair informação de ambos os métodos geofísicos.Este modelo contém regiões caracterizadas por relações consistentes entre os parâmetros. Resultados obtidos com dados sintéticos e de campo foram usados para mostrar que o uso da informação contida nos dois conjuntos de dados conduz a melhores resultados. O método desenvolvido nesta tese foi aplicado, com resultados satisfatórios, a um conjunto de dados reais obtidos na Faixa Piritosa.Fundação para a Ciência e Tecnologia (FCT, SFRH/BD/66455/2009

RAINFALL INSURANCE IN WHEAT PRODUCTION WITH WEATHER DERIVATIVES

It has been long known that weather conditions are the main factor of uncertainty in plant production. For this reason, an integrated system of risk management in plant production is necessary today, in order to somewhat compensate for the loss caused by weather risks. In the past, farmers have bought insurance for protection against fluctuations in crop yields caused by weather risks. Relatively new tools for risk management in plant production are weather derivatives. Although weather derivatives show many advantages over traditional insurance the market for these products is still relatively limited. Therefore it is necessary to quantify the effect of risk reducing that can be achieved by using weather derivatives on the example of selected farm in Germany. If the field of production is close to the meteorological station, and if a high correlation between weather indices and yield is assumed, then the effect of risk reducing is significant (over 30 %)

A critical analysis of the pisa mathematics tasks

© 2019, FACTEACHEREDUCATION. All rights reserved. In this paper, the authors deal with a critical analysis of some of the problems associated with PISA testing in mathematics. First of all, the social, economic and political circumstances of the launch of the PISA project are pointed out. This is followed by an analysis of what the authors consider as very important concepts for understanding PISA philosophy, such as applicable knowledge and problem solving in a real-life situation. We compared two different ways of defining these concepts and showed what the consequences of learning and teaching mathematics are in each of the cases. The authors present the results of the research that was conducted with mathematics teachers, as well as teachers of other subjects. The research dealt with the determination of the importance and role of the mathematical tasks of the PISA test for students’ further mathematical education. The results of the research have shown that there is a significant statistical difference between the assessment provided by the teachers who do and those who do not teach mathematics. The paper also analysed some specific tasks that the students were solving in PISA tests. The authors point out some deficiencies and inaccuracies observed in the mathematics tasks on PISA tests, as well as the weaknesses of PISA testing itself

A solution to the inverse problem for the Sturm-Liouville-type equation with a delay

The paper is devoted to study of the inverse problem of the boundary spectral assignment of the Sturm-Liouville with a delay. -y″(x) + q(x)y(α · x) = λy(x); q ∈ AC[0; π];α ∈ (0, 1] (1) with separated boundary conditions: y(0) = y(π) = 0 (2) y(0) = y′(π) = 0 (3) It is argued that if the sequence of eigenvalues is given λn(1) n and λn(2) n tasks (1-2) and (1-3) respectively, then the delay factor α ∈ (0, 1) and the potential q ∈ AC[0, π] are unambiguous. The potential q is composed by means of trigonometric Fourier coefficients. The method can be easily transferred to the case of α = 1 i.e. to the classical Sturm-Liouville problem

DINAMIC OF BIOENERGETIC POTENTIAL OF SOIL IN VOJVODINA

Bioenergetic potential of the soil (expressed as total dry matter produced) does not use the same intensity. In certain periods exercised proper growth of production, while the other observes at first fatigue, then its often pronounced decline and finally a slight increase. The paper concludes dependence between the quantity of all forms of active substances (N, P2O5, K2O) that is stored in the soil and the volume of produced organic mass expressed as absolute dry substance. Is an open question whether the production could increase in the coming period to a level that is accomplished by three decades ag

Properties of Calcium Phosphate Cements With Different Tetracalcium Phosphate and Dicalcium Phosphate Anhydrous Molar Ratios

Calcium phosphate cements (CPCs) were prepared using mixtures of tetracalcium phosphate (TTCP) and dicalcium phosphate anhydrous (DCPA), with TTCP/ DCPA molar ratios of 1/1, 1/2, or 1/3,with the powder and water as the liquid. Diametral tensile strength (DTS), porosity, and phase composition (powder x-raydiffraction) were determined after the set specimens have been immersed in a physiological-like solution (PLS) for 1 d, 5 d, and 10 d. Cement dissolution rates in an acidified PLS were measured using a dual constant composition method. Setting times ((30 ± 1) min) were the same for all cements. DTS decreased with decreasing TTCP/DCPA ratio and, in some cases, also decreased with PLS immersion time. Porosity and hydroxyapatite (HA) formation increased with PLS immersion time. Cements with TTCP/DCPA ratios of 1/2 and 1/3, which formed calciumdeficient HA, dissolved more rapidly than the cement with a ratio of 1/1. In conclusion, cements may be prepared with a range of TTCP/DCPA ratios, and those with lower ratio had lower strengths but dissolved more rapidly in acidified PLS

Theories on the beginnings and structure of joint-families ("zadruga")

In this paper the author has a critical standpoint toward the most known theories on joint family communities. The works of the up-to-now called Yugoslav authors were put in the foreground. The works of foreign authors were placed after. They were classified by a general criterion, by how the authors saw the origins of this form of family. The comprehension of the basic characteristics depends, as a rule, on that, as well as the elements structure, changing processes, adjustment to new conditions and extinction of the joint family community. The first part of this article is devoted to theories about family communities as an institution of the Slavs. In this way its origin is connected with elements of a certain ethnic community. The range and consequences of such beliefs are suggested. The second part is reserved to explaining the family community as an institution which appeared in feudalism. It is a consequence of the tax system role. With its termination, the communities fell apart. This kind of social development determination and this type of family is proven to be ahistorical. It is predominantly stressed that the authors neglected that feudalism was a class society and overemphasized the force factor significance. The third part deals with theories which believe joint-family communities as an institution which arose in the transition from tribal to class society. These researchers stress that it is a general, historically determined conditioned form, which originated before class society and terminated with its development. Elements of its structure are especially important, as well as methods of its transformation in new conditions and termination processes. The essence of this belief is the following: a joint-family is a general historical form of family organization which arose in the transition from tribal to class society. The most important characteristics are: 1) blood relationship among men members; 2) common property; 3) undeveloped division of labor, and plain peoples work is the most important for its survival; 4) democratic control; and 5) it is not just mere gathering of simple families it is based on kinship, origin and precedes monogrammed families