The bulk modulus of pure hydraulic oil and its dependency on pressure and temperature has been studied extensively over the past years. A comprehensive review of some of the more common definitions of fluid bulk modulus is conducted and comments on some of the confusion over definitions and different methods of measuring the fluid bulk modulus are presented in this thesis. In practice, it is known that there is always some form of air present in hydraulic systems which substantially decreases the oil bulk modulus. The term effective bulk modulus is used to account for the effect of air and/or the compliance of transmission lines. A summary from the literature of the effective bulk modulus models for a mixture of hydraulic oil and air is presented. Based on the reviews, these models are divided into two groups: “compression only” models and “compression and dissolve” models. A comparison of various “compression only” models, where only the volumetric compression of air is considered, shows that the models do not match each other at the same operating conditions. The reason for this difference is explained and after applying some modifications to the models, a theoretical model of the “compression only” model is suggested. The “compression and dissolve” models, obtained from the literature review, include the effects of the volumetric compression of air and the volumetric reduction of air due to the dissolving of air into the oil. It is found that the existing “compression and dissolve” models have a discontinuity at some critical pressure and as a result do not match the experimental results very well. The reason for the discontinuity is discussed and a new “compression and dissolve” model is proposed by introducing some new parameters to the theoretical model. A new critical pressure (PC) definition is presented based on the saturation limit of oil. In the new definition, the air stops dissolving into the oil after this critical pressure is reached and any remaining air will be only compressed afterwards. An experimental procedure is successfully designed and fabricated to verify the new proposed models and to reproduce the operating conditions that underlie the model assumptions. The pressure range is 0 to 6.9 MPa and the temperature is kept constant at °C. Air is added to the oil in different forms and the amount of air varies from about 1 to 5%. Experiments are conducted in three different phases: baseline (without adding air to the oil), lumped air (air added as a pocket of air to the top of the oil column) and distributed air (air is distributed in the oil in the form of small air bubbles). The effect of different forms and amounts of air and various volume change rates are investigated experimentally and it is shown that the value of PC is strongly affected by the volume change rate, the form, and the amount of air. It is also shown that the new model can represent the experimental data with great accuracy. The new proposed “compression and dissolve” model can be considered as a general model of the effective bulk modulus of a mixture of oil and air where it is applicable to any form of a mixture of hydraulic oil and air. However, it is required to identify model parameters using experimental measurements. A method of identifying the model parameters is introduced and the modeling errors are evaluated. An attempt is also made to verify independently the value of some of the parameters. The new proposed model can be used in analyzing pressure variations and improving the accuracy of the simulations in low pressure hydraulic systems. The new method of modeling the air dissolving into the oil can be also used to improve the modeling of cavitation phenomena in hydraulic systems.

Submitted by Cláudia Bueno (claudiamoura18@gmail.com) on 2016-04-06T17:13:53Z No. of bitstreams: 2 Dissertação - Pâmella Almeida Quintino Jordan - 2015.pdf: 2688001 bytes, checksum: 877af9d2fad9e949f2e145fa570a729b (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-04-07T10:48:02Z (GMT) No. of bitstreams: 2 Dissertação - Pâmella Almeida Quintino Jordan - 2015.pdf: 2688001 bytes, checksum: 877af9d2fad9e949f2e145fa570a729b (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2016-04-07T10:48:02Z (GMT). No. of bitstreams: 2 Dissertação - Pâmella Almeida Quintino Jordan - 2015.pdf: 2688001 bytes, checksum: 877af9d2fad9e949f2e145fa570a729b (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2015-07-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / In the field of applied mathematics, the study of numerical methods has its relief importance and it shows a vast variety. In this word will be study four these methods: Bisection, Newton, Secant and Monte Carlo. The first three are methods studied in Numerical Calculus discipline, normally given in graduation from Exactn Science; their goal is the calculation of real functions roots; they work through recurrent sequence converge the exact roots. One of the applications of the fourth method is the calculation of the area under a curve, using, for this, random numbers. In each method we will study the motivation followed of their eff ectiveness. As we will see, there are many areas that need methods, as studied here, for solving problems; the engineering, Chemistry, Physics and Biology are just some of them. In order to demonstrate the importance of the four methods we will present situations that can be applied. Demonstrated the need and eff ectiveness of all methods, we can understand them as an excellent alternative to solving problems in mathematics applied area, especially when conventional resolution methods cannot play a satisfactory role. We must emphasize, also, the importance of using software and computer programs to better performance of the methods. / No campo da matemática aplicada o estudo de métodos numéricos tem sua relevada importância e apresenta uma vasta variedade. Neste trabalho serão estudados quatro destes métodos: Bissecção, Newton, Secante e Monte Carlo. Os três primeiros são métodos estudados na disciplina de Cálculo Numérico, normalmente ministrado nas graduações das Ciências Exatas; o objetivo deles é o cálculo de raízes de funções reais; eles trabalham através de sequências recorrentes que convergem para as raízes exatas. Uma das aplicações do quarto método é o cálculo da área sob uma curva, utilizando, para isso, números aleatórios. Em cada método estudaremos a motivação seguida de sua comprovada eficácia. Como veremos, são muitas as áreas que necessitam de métodos, como os aqui estudados, para resolução de problemas; as engenharias, a Química, a Física e a Biologia são apenas algumas delas. A fi m de demonstrar a importância dos quatro métodos apresentaremos situações em que podem ser aplicados. Demonstrada a necessidade e e ficiência de todos os métodos, podemos compreendê-los como uma excelente alternativa para resolução de problemas na área da matemática aplicada, principalmente quando os métodos convencionais de resolução não conseguem desempenhar papel satisfatório. Devemos enfatizar, ainda, a importância do uso de softwares e programas computacionais para melhor desempenho dos métodos.

The aim of this thesis is to investigate the tensor decomposition of structured tensors related to SL(n)-irreducible representations. Structured tensors are multilinear objects satisfying specific symmetry relations and their decompositions are of great interest in the applications. In this thesis we look for the decompositions of tensors belonging to irreducible representations of SL(n) into sum of elementary objects associated to points of SL(n)-rational hoogeneous varieties. This family includes Veronese varieties (symmetric tensors), Grassmann varieties (skew-symmetric tensors), and flag varieties. A classic tool to study the decomposition of symmetric tensors is the apolarity theory, which dates back to Sylvester. An analogous skew-symmetric apolarity theory for skew-symmetric tensors have been developed only few years ago. In this thesis we describe a global apolarity theory called Schur apolarity theory, which is suitable for tensors belonging to any irreducible representation of SL(n). Examples, properties and applications of such apolarity are studied with details and original results both in algebra and geoemtry are provided.

First in this dissertation we make a brief overview about basic tools of commutative algebra required for understanding the rest of the text. Then, we present the definition of symbolic powers and we discuss their basic properties, mainly emphasizing questions such as primary decomposition and calculation of generators. We conclude this work by showing actual results that relate the symbolic powers with other notions in commutative algebra and algebraic geometry. / Nesta dissertação fazemos inicialmente um breve apanhado sobre ferramentas básicas de álgebra comutativa úteis para o entendimento do resto do texto. Em seguida, apresentamos a definição de potências simbólicas e discutimos suas propriedades mais elementares, destacando sobretudo questões como decomposição primária e cálculo de geradores. Finalizamos o trabalho mostrando resultados atuais que relacionam as potências simbólicas com outras noções da álgebra comutativa e geometria algébrica.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The notion of symbolic power dates back to W. Krull, who used it in the proof of the famous theorem of principal ideal, this a crucial milestone in the short history of commutative algebra. Later, O. Zariski, M. Nagata, D. Rees and others have shown how this purely algebraic notion has important signi cance in algebraic geometry. In this paper we study the symbolic powers showing some of its most fundamental properties and their connections with various aspects of algebraic geometry and commutative algebra. / A no ção de potência simb ólica remonta a W. Krull, que a usou na prova do c élebre teorema do ideal principal, este um marco crucial na curta hist ória da álgebra comutativa. Mais adiante, O. Zariski, M. Nagata, D. Rees e outros mostraram como esta no ção puramente alg ébrica tem importante signi ficado em geometria alg ébrica. Neste trabalho estudaremos as potências simb ólicas evidenciando algumas de suas propriedades mais fundamentais e suas conexões com aspectos variados da geometria alg ébrica e álgebra comutativa.

Drilled shaft retaining walls are common earth retaining structures, well suited to urban environments where noise, space, and damage to adjacent structures are major considerations. The design of drilled shaft retaining walls in non-expansive soils is well established. In expansive soils, however, there is no consensus on the correct way to account for the influence of soil expansion on wall behavior. Based on the range of design assumptions currently in practice, existing walls could be substantially over- or under-designed. The goal of this research is to advance the understanding of the effects of expansive clay on drilled shaft retaining walls. The main objectives of this study are to identify the processes responsible for wall loading and deformation in expansive clay, to evaluate how these processes change with time, and to provide guidance for design practice to account for these processes and ensure adequate wall performance. The primary source of information for this research is performance data from a four-year monitoring program at the Lymon C. Reese research wall, a full-scale instrumented drilled shaft retaining wall constructed through expansive clay in Manor, Texas. The test wall was instrumented with inclinometers and fiber optic strain gauges, and performance data was recorded during construction, excavation, during natural moisture fluctuations, and during controlled inundation tests that provided the retained soil with unlimited access to water. In addition to the test wall study, a field assessment of existing TxDOT drilled shaft retaining walls was conducted. The main process influencing short-term wall deformation was found to be global response to stress relief during excavation, which causes the wall and soil to move together without the development of large earth pressures or bending stresses. Long-term wall deformations were governed by the development of drained conditions in both the retained soil and the foundation soil after approximately eight months of controlled inundation testing. To ensure adequate wall performance, the deformations and structural loads associated with short- and long-term conditions should be combined and checked against allowable values. / text

The study of quadrupolar nuclei using NMR spectroscopy in the solid state significantly increased in popularity from the end of the 20th century, with the introduction of specific methods to acquire spectra free from the effects of the quadrupolar interaction, that results in broadened lineshapes that cannot be completely removed by spinning the sample at the magic angle (MAS), unlike most of the other interactions present in the solid state. The first technique which allows, without any specific hardware, the removal of this broadening has been the Multiple-Quantum MQMAS experiment. The method quickly gained a popularity within the NMR community, with numerous successful applications published. However, the multiple-quantum filtration step in this experiment relies on severely limits sensitivity, restricting application to the most sensitive nuclei. Extending the applicability of MQMAS to less receptive nuclei requires the use of signal improvement techniques. There are multiple examples of such approaches in the literature, but most of these require additional optimisation that may be time-consuming, or simply impossible, on less receptive nuclei. This work introduces a novel signal improvement technique for MQMAS, called FAM-N. Its optimisation is solely based on density matrix simulations using SIMPSON, implying no additional experimental optimisation is required, while improving the signal in MQMAS spectra by equivalent or higher amounts than other common methods. In order to prove the applicability of this method on virtually any system, FAM-N has been investigated by simulation, and tested experimentally using a number of model samples, as well as samples known to be challenging to study by NMR. This work also explores other aspects of NMR spectroscopy on quadrupolar nuclei. Adiabatic inversion of the satellite populations can be performed to improve the central transition signal in static or MAS spectra. A range of methods has been tested and compared, with particular attention given to hyperbolic secant-shaped pulses, for which its performance have been described. Finally, cross-polarisation from a spin I = 1/2 nucleus to a quadrupolar nucleus has been investigated. After reviewing the theory for the static case, simulations have been performed under MAS in order to identify the conditions for efficient magnetisation transfer, with applications in spectral editing or for the combination with MQMAS.

The topic of the master’s thesis is the statically compliant and economical design of the ensuring of foundation pit for building Carla Brno. The calculation part will be solved through program GEO5. The part of this thesis is also to describe the technological process of implementing elements and the relevant project documentation.

Målet med rapporten är att redovisa erforderliga maskiner, personal och erfarenhetsdata för sekantpålning. Detta kan utnyttjas vid jämförelse med andra pålningsmetoder av företag.   Sekantpålning används som en stödkonstruktion, vars uppgift är att stötta jordmassor vid schakt. De positiva egenskaperna med denna är en bidragande faktor till ett ökat utnyttjande av metoden. Genom att uppnå lägre vibrationsnivåer och minimera grundvattensänkning får metoden ett ökat mervärde. Sekantpålningsmetoden används i större utsträckning utomlands och det är först nu den börjar brukas i Sverige. Genom att Trafikverket har godkänt sekantpålning som en permanent konstruktion, kan metoden bryta ny mark i Sverige. Sekantpålningsmetoden i sig påverkas ej av det svenska mark- och klimatförhållandet. Det är den teknik som man utnyttjar vid sekantpålningen, som påverkas av de geologiska och hydrogeologiska förutsättningarna. Mark som består av rikligt med stenblock eller varierande sten storlekar bör man använda CSP-tekniken med foderrörsborrning. Tekniker som inte klarar av dessa markförhållanden är CFA och CAP, som istället utnyttjar en augerborr. Dessa tekniker utnyttjas när marken består av fastlera eller friktionsjord, vilket gör arbetet för augerborren betydligt lättare än om marken består av stenblock.   Slutsatsen i rapporten visar att sekantpålning är det dyrare alternativet och att metoden inte kan konkurrera med de mer konventionella stödkonstruktionerna ur kostnadssynpunkt. För att sekantpålningen ska vara fördelaktig måste metoden ses ur ett större perspektiv och hänsyn tas till omgivningspåverkan och markförhållanden. På så sätt kan ett mervärde skapas. Metoden lämpar sig väl i innerstadsmiljö med närliggande byggnader, då buller och vibrationer är en påverkande faktor. Projekt som har utnyttjat sekantpålningsmetoden har varierande kostnader, då de har använt olika sekantpålningstekniker. Vid Norra länken 12 och 22 tillämpades CSP-tekniken som hade en kapacitet till att göra 2,5 pålar per dag till en kostnad av 11.500 kr/m². Vid Bargers plats i Malmö tillämpades CFA-tekniken till en kostnad av 2.500 kr/m². Vid Folkungagatan i Stockholm användes CAP-tekniken till en kostnad av 4.500 kr/m². Metoden har både för och nackdelar. Fördelarna är att metoden är flexibel vilket innebär att den kan anpassas efter önskad geometri. Metoden bidrar till mindre vibrationer som i sin tur minimerar risken för sättningar. Nackdelarna är att sekantpålning är dyrare än konventionella stödkonstruktioner p.g.a. att metoden är tidskrävande. Vid sekantpålning som permanent stödkonstruktion görs efterspänning av ankarstag som är tidskrävande. I rapporten presenteras byggprojekt där sekantpålning använts. Projekt som redovisas i rapporten är Odenplan station, Spjutmo kraftstation, Norra länken 12 och 22, Bagers plats och Folkungagatan. / The goal of the report is to present machines, staff and requisite experience data within secant piling. The information may be utilized in comparison with other piling methods by corporations. Secant piling is used as a support structure whose task is to keep the soil from sliding in to the pit during excavation. Its positive aspects of the environment are a contributing factor to increased use of the method. By achieving lower vibration levels and minimize the reduction in the groundwater level, the method adds value. The secant pile method is extensively used abroad and nowadays it begins to be operated in Sweden. Now when Trafikverket has approved secant piling as a permanent structure, the method can lead to more usage in Sweden. The secant pile method in itself is not affected by the Swedish soil and climatic condition. It is the technique you are utilizing when using secant piling that’s affected by the geological and hydrogeological conditions. Soil that is consisting of boulders or variable stone sizes should use CSP technology with casing drilling. Techniques that don’t work in these soil conditions is CFA and CAP, which instead uses an auger drill. These techniques are utilized when the soil consists of solid clay or friction soil, which makes the work of the auger drill much easier than if the land consists of stone blocks. The conclusion of the report indicate that secant piles are the more expensive option, and that the method cannot compete with the more conventional support structures in that regard. To understand that secant piles will be beneficial the method must be seen from a broader perspective and you have to look at the impact of the surroundings and the soil conditions. In this way, added value is created. The method is suitable in urban setting with nearby buildings, where noise and vibration is an influencing factor. Projects that have embraced the secant pile method have varying costs, since they have used different secant pile techniques. At Norra länken 12 and 22 they used the CSP technology that had a capacity to make 2.5 piles per day at a cost of 11,500 SEK/m². In Bagers Plats in Malmö they used the CFA technology at a cost of 2,500 SEK/m². At Folkungagatan in Stockholm they used the CAP technology at a cost of 4,500 SEK/m². The method has both advantages and disadvantages. The advantages are that the method is flexible which means that it can be adapted to the desired geometry. This method helps to reduce vibration, which in turn minimizes the risk of subsidence. The disadvantages are that secant piling is more expensive than conventional supporting structures because of the method is time consuming. When secant piles that are used as a permanent support structure the anchor rods have to be tightened often and that is time consuming. The report presents the construction projects where secant piling is used. Projects presented in the report are Odenplan station, Spjutmo kraftstation, Norra länken 12 and 22, Bagers plats and Folkungagatan.

Cette thèse d'algèbre commutative porte principalement sur la théorie de la profondeur. Nous nous efforçons d'en fournir une approche épurée d'hypothèse noethérienne dans l'espoir d'échapper aux idéaux premiers et ceci afin de manier des objets élémentaires et explicites. Parmi ces objets, figurent les complexes algébriques de Koszul et de Cech dont nous étudions les propriétés cohomologiques grâce à des résultats simples portant sur la cohomologie du totalisé d'un bicomplexe. Dans le cadre de la cohomologie de Cech, nous avons établi la longue suite exacte de Mayer-Vietoris avec un traitement reposant uniquement sur le maniement des éléments. Une autre notion importante est celle de dimension de Krull. Sa caractérisation en termes de monoïdes bords permet de montrer de manière expéditive le théorème d'annulation de Grothendieck en cohomologie de Cech. Nous fournissons également un algorithme permettant de compléter un polynôme homogène en un h.s.o.p.. La profondeur est intimement liée à la théorie des résolutions libres/projectives finies, en témoigne le théorème de Ferrand-Vasconcelos dont nous rapportons une généralisation due à Jouanolou. Par ailleurs, nous revenons sur des résultats faisant intervenir la profondeur des idéaux caractéristiques d'une résolution libre finie. Nous revisitons, dans un cas particulier, une construction due à Tate permettant d'expliciter une résolution projective totalement effective de l'idéal d'un point lisse d'une hypersurface. Enfin, nous abordons la théorie de la régularité en dimension 1 via l'étude des idéaux inversibles et fournissons un algorithme implémenté en Magma calculant l'anneau des entiers d'un corps de nombres. / This Commutative Algebra thesis focuses mainly on the depth theory. We try to provide an approach without noetherian hypothesis in order to escape prime ideals and to handle only basic and explicit concepts. We study the algebraic complexes of Koszul and Cech and their cohomological properties by using simple results on the cohomology of the totalization of a bicomplex. In the Cech cohomology context we established the long exact sequence of Mayer-Vietoris only with a treatment based on the elements. Another important concept is that of Krull dimension. Its characterization in terms of monoids allows us to show expeditiously the vanishing Grothendieck theorem in Cech cohomology.We also provide an algorithm to complete a omogeneous polynomial in a h.s.o.p.. The depth is closely related to the theory of finite free/projective resolutions. We report a generalization of the Ferrand-Vasconcelos theorem due to Jouanolou. In addition, we review some results involving the depth of the ideals of expected ranks in a finite free resolution.We revisit, in a particular case, a construction due to Tate. This allows us to give an effective projective resolution of the ideal of a point of a smooth hypersurface. Finally, we discuss the regularity theory in dimension 1 by studying invertible ideals and provide an algorithm implemented in Magma computing the ring of integers of a number field.