Na prática de fundações por estacas helicoidais submetidas a esforços de tração (também conhecidas como ancoragens helicoidais) frequentemente são observadas discrepâncias entre valores de capacidade de carga previstos por métodos teóricos e medidos em provas de carga. Entre outros fatores, estas diferenças ocorrem pelo fato de nenhum dos métodos teóricos existentes considerarem adequadamente o efeito da instalação no comportamento deste tipo de ancoragem. Durante a penetração por rotação das hélices da estaca/ancoragem no terreno, os parâmetros de resistência e de rigidez do solo penetrado, e as tensões radiais em torno da estaca são modificados. O nível de degradação do solo que suportará as cargas aplicadas na ancoragem é dependente do tipo e características do solo, e do número e geometria das hélices. Diante deste cenário de incertezas provenientes do efeito da instalação, duas distintas abordagens probabilísticas são apresentadas nesta dissertação. A primeira abordagem tem o intuito de verificar o efeito da variabilidade de distintas variáveis influentes no comportamento de ancoragens helicoidais. Para este fim, foi utilizado o método de expansão em Polinômio de Caos, baseado na modelagem numérica de ancoragens helicoidais em areia, calibrada com os resultados medidos em modelos testados em centrifuga. Foi verificado nesta parte o nível de influência de cada parâmetro de entrada do solo no comportamento carga x deslocamento da ancoragem. No segundo enfoque, foi proposto e avaliado um modelo probabilístico para simular a curva carga x deslocamento, obtida em provas de carga. Nesta parte, foi realizada uma análise de confiabilidade para verificação do estado limite de serviço de ancoragens helicoidais baseada em resultados de provas de carga executadas no Brasil. São também apresentadas nesta análise as incertezas provenientes da variabilidade do fator de torque utilizado na verificação da capacidade de carga durante a instalação da ancoragem. / Discrepancies between predicted and measured results of uplift capacity of helical piles (or helical anchors) have been commonly observed in the practical experience. Among other factors, these differences occur because the existing theoretical methods do not consider adequately the installation effect on the behavior of this type of anchor. During the anchor installation, the penetration by rotation of the helical plates into the ground modifies the soil strength and stiffness parameters, and the radial stresses around the pile. The degradation degree of the soil penetrated is dependent on the type and characteristics of the soil, and also on the number and geometry of helices. Against this background of uncertainty due to the installation effect, two different probabilistic approaches are presented in this dissertation. The first approach is used to verify the effect of the variability of different influential variables on the behavior of helical anchors. For this purpose, the probabilistic method named Sparse Polynomial Chaos Expansion was used, based on the numerical modeling of helical anchors in sand, calibrated with measured results obtained from reduced models tested in centrifuge. As a result, the level of influence of each soil input parameter on the anchor load-displacement behavior is presented. In the second approach, a probabilistic model to simulate the load-displacement curve obtained in load tests was proposed and evaluated. For this part, a reliability analysis was performed to check the serviceability limit state of helical anchors, based on the results of field load tests performed in Brazil. In addition, the uncertainties arising from the variability of the torque factor were evaluated. The torque factor is frequently used to verify the uplift capacity of helical anchors during installation.

Membrane proteins roughly constitute 30% of open reading frames in a genome and form 70% of current drug targets. They are classified as integral, peripheral membrane proteins and polypeptide toxins. α-helices and β -strands are the principal secondary structures observed in integral membrane proteins. This thesis presents the results of studies on analysis and correlation of sequence and structure of helices constituting integral helical membrane proteins. The aim of this work is to understand the helix stabilization, distortion as well as packing in terms of amino acid sequences and the correlated structures they adopt. To this end, analyses of datasets of X-ray crystal structures of integral helical membrane proteins and their comparison with a dataset of representative folds of globular proteins was carried out. Initial analysis was carried out using a non-redundant dataset of 75 membrane proteins to understand sequence and structural preferences for stabilization of helix termini. The subsequent analysis of helix distortions in membrane proteins was carried out using an updated dataset of 90 membrane proteins. Chapter 1 of the thesis reviews experimental as well as theoretical studies that have provided insights into understanding the structure of helical membrane proteins. Chapter 2 details the methods used during the course of the present investigations. These include the protocol used for creation of the non-redundant database of membrane and globular proteins. Various statistical methods used to test significance of the position-wise representation of amino acids in helical regions and the differences in globular and membrane protein datasets have been listed. Based on the tests of significance, a methodology to identify differences in propensity values that are statistically significant among two datasets has been devised. Programs used for secondary structure identification of membrane proteins namely Structure Identification (STRIDE) and Assignment of Secondary Structure in Proteins (ASSP) as well as those used for characterization of helical geometry (Helanal-Plus) have also been enlisted. In Chapter 3, datasets of 865 α-helices in 75 membrane proteins and 2680 α- helices from 626 representative folds in globular proteins defined by the STRIDE program have been analyzed to study the sequence determinants at fifteen positions within and around the α-helix. The amino acid propensities have been studied for positions that are important for the process of helix initiation, propagation, stabilization and termination. Each of the 15 positions has unique sequence characteristics reflecting their role and contribution towards the stability of the α-helix. A comparison of the sequence preferences in membrane and globular proteins revealed common residue preferences in both these datasets confirming the importance of these positions and the strict residue preferences therein. However, short/medium length α-helices that initiated/terminated within the membrane showed distinct amino acid preferences at the N-terminus (Ncap, N1, N2) as well as the C-terminus ( Ccap, Ct) when compared to α-helices belonging to membrane and globular proteins. The sequence preferences in membrane proteins were governed by the helix initiating and terminating property of the amino acids as well as the external environment of the helix. Results from our analysis also conformed well with experimentally tested amino acid preferences in a position-specific amino acid preference library of the rat neurotensin receptor (Schlinkmann et al (2012) Proc Natl Acad Sci USA 109(25):1890-5) as well as crystal structures of GPCR proteins. In the light of the environment dependent amino acid preferences found at α- helix termini, a survey was carried out to find various helix capping motifs adopted at both termini of α-helices in globular and membrane proteins to stabilize these helix termini. The results from these findings have been reported in Chapter 4. A sequence dependent structural preference is found for capping motifs at helix termini embedded inside and protruding outside the membrane. The N-terminus of α-helices was capped by hydrogen bonds involving free main chain amide groups of the first helical turn as donors and amino acid side chains as acceptors, as against the C-terminus which showed position-dependent characteristic backbone conformations to cap the helix. Overall helix termini inside the membrane did not show a very high number of capping motifs; instead these termini were stabilized by helix- helix interactions contributed by the neighboring helices of the helical bundle. In Chapter 5, we examine transmembrane helical (TMH) regions to identify as well as characterize the various types of helix perturbations in membrane proteins using ASSP and Helanal-Plus. A survey of literature shows that the term ‘helix kink’ has been used rather loosely when in fact helical regions show significant amounts of variation and transitions in helical parameters. Hence a systematic analysis of TMH regions was undertaken to quantify different types of helix perturbations, based on geometric parameters such as helical twist, rise per residue and local bending angle. Results from this analysis indicated that helices are not only kinked but undergo transitions to form interspersed stretches of 310 helices and π-bulges within the bilayer. These interspersed 310 and π-helices showed unique sequence preferences within and around their helical body, and also assisted in main- taining the helical structure within the bilayer. We found that Proline not only kinked the helical regions in a characteristic manner but also caused a tightening or unwinding in a helical region to form 310 and π-helix fragments respectively. The helix distortions also resulted in backbone hydrogen bonds to be missed which were stabilized by hydrogen bonds from neighboring residues mediated by their side chain atoms. Furthermore, a packing analysis showed that helical regions with distortions were able to establish inter-helical interactions with more number of transmembrane segments in the helical bundle. The study on helix perturbations presented in the previous chapter, brought to light a previously unreported 19 amino acid π-helix fragment interspersed between α-helices in the functionally important transmembrane helix 2 (TM2) belonging to Mitochondrial cytochrome-c-oxidase (1v55). Chapter 6 describes a case study of the structurally similar but functionally different members within the Heme-Copper- Superoxidases (HCO) superfamily that were considered for a comparative analysis of TM2. An analysis of 7 family members revealed that the π-helix shortens, fragments in two shorter π-helices or was even absent in some family members. The long π-helix significantly decreased the total twist and rise of the entire helical fragment thus accommodating more hydrophobic amino acids within the bilayer to avoid hydrophobic mismatch with the bilayer. The increased radius of the TM2 helical fragment also assisted in helix packing interactions by increasing the number of residues involved in helix-helix interactions and hydrogen bonds. Chapter 7 documents the conclusions from the different analyses presented in each of the above chapters. Overall, it is found that membrane proteins optimize the biophysical and chemical constraints of the external environment to strategically place select amino acids at helix termini to ‘start’ and ‘stop’ α-helices. The stabilization of these helix termini is a consequence of sequence dependent structural preferences to form helix capping motifs. The studies on helix transitions and distortions highlight that membrane proteins are not only packed as α-helices but also accomodate 310- and π-helical fragments. These transitions and distortions help in harboring more hydrophobic amino acids and aiding inter-helical interactions important for maintaining the fold of the membrane protein. Appendix A describes a comparison of α-helix assignments in globular and membrane proteins by two algorithms, one based on Cα trace (ASSP) and the other using a combination of hydrogen bond pattern along with backbone torsion angles φ and ψ (STRIDE).

Helical tube bundles are usually used in the steam generator (SG) of High-Temperature Gas-Cooled Reactors (HTGRs) as the heat transfer area. The helical tube bundle is composed of multiple-layer helically coiled tubes, which are fixed by multiple sets of supporting structures. There are ideal flow paths separated by different layers of helical tubes. The velocity non-uniformity for different flow paths will affect the heat transfer tube temperature and the outlet steam temperature uniformity of different tube layers. In the shell side of the SG, turbulent cross flow over helical tube bundles are complicated and difficult to predict due to reverse pressure gradient and boundary layer separation. Due to the huge amount of computation resources consumption, there are few numerical simulation studies on the non-uniformity of cross flow over large-volume helical tube bundles.Two cases, namely the flow past a circular cylinder and cross flow over in-line tube bundles, are simulated to validate if Partially-Averaged Navier-Stokes (PANS) model is suitable for simulations of cross flow over helical tube bundles. The simulation results of k-ω SST PANS model are well agree with the average and local experimental data. Therefore, k-ω SST PANS model is used to investigate the influences of the supporting structure and helical diameter on the non-uniformity of cross flow over ideal helical tube bundles. The helix angle of helical tube bundle is neglected. The computational domain consists of 5 rows of helically coiled tubes in the streamwise direction. Periodic boundary conditions are used for the inlet and outlet to reduce the consumption of computing resources.For cross flow over helical tube bundles, there exists significant circumferential and radial velocities, which means there are secondary flows in the plane perpendicular to the streamwise direction. The radial velocity is about 16% of the streamwise velocity. Due to the presence of secondary flow, cross flow over individual tube is inclined, and the inclination direction changes at different circumferential positions. At the same circumferential position, the flow inclination direction is the same along the streamwise direction and radial direction. For helical tube bundles, the ratio of the blocking area to the flow area (blocking area ratio) of the inner, outer and middle flow paths are different. The blocking area ratio of the inner flow path is large, and the blocking area ratio of the outer flow path is small, resulting in non-uniform velocity distribution in different flow paths.Cross flow over helical tube bundles with three helical diameters (inner wall radius Ri is 0.02 m, 0.14 m and 0.26 m, respectively) are simulated. For small helical diameter tube bundle (Ri = 0.02 m), the maximum streamwise velocity non-uniformity is 16.6%. For tube bundles with middle and large helical diameters (Ri = 0.14 m and 0.26 m), the maximum streamwise velocity non-uniformity is 6.7% and 5.8%, respectively. The results show that the flow non-uniformity becomes more obvious for small helical diameter.The supporting structures results in more complex secondary flows. The secondary flows far from the supporting structures are larger than those in the region near the supporting structures. The supporting structures causes the blocking area ratio of inner, outer and middle flow paths vary with the helical diameter, and the blocking area ratio non-uniformity is larger than that without supporting structures. In the presence of supporting structures, the maximum streamwise velocity non-uniformities of small, middle and large helical diameter tube bundles are 22.0%, 8.8% and 6.3%, respectively. The effect of supporting structures on the flow non-uniformity increases as the helical diameter decreases. / Spiralformade rörknippen används vanligtvis i ånggeneratorn (SG) i gaskylda högtemperaturreaktorer (HTGR) som värmeöverföringsområde. Det spiralformade rörknippet består av flerskikts spiralformade rör, som är fixerade av flera uppsättningar stödkonstruktioner. Det finns idealiska flödesvägar åtskilda av olika lager av spiralformade rör. Hastighetsojämnheten för olika flödesvägar kommer att påverka värmeöverföringsrörets temperatur och utloppsångans temperaturlikformighet för olika rörskikt. På skalsidan av SG är turbulent tvärflöde över spiralformade rörknippen komplicerade och svåra att förutsäga på grund av omvänd tryckgradient och gränsskiktsseparation. På grund av den enorma förbrukningen av beräkningsresurser finns det få numeriska simuleringsstudier om ojämnheten i tvärflödet över spiralformade rörknippen med stora volymer.Två fall, nämligen flödet förbi en cirkulär cylinder och korsflödet över in-line rörknippen, simuleras för att validera om PANS-modellen (Partially-Averaged Navier-Stokes) är lämplig för simuleringar av tvärflöde över spiralformade rörknippen. Simuleringsresultaten för k-ω SST PANS-modellen stämmer väl överens med genomsnittliga och lokala experimentella data. Därför används k-ω SST PANS-modellen för att undersöka påverkan av stödstrukturen och spiraldiametern på ojämnheten i tvärflödet över ideala spiralformade rörknippen. Helixvinkeln för spiralformad rörbunt försummas. Beräkningsdomänen består av 5 rader spiralformade rör i strömriktningen. Periodiska randvillkor används för inlopp och utlopp för att minska förbrukningen av datorresurser.För tvärflöde över spiralformade rörknippen finns det signifikanta perifera och radiella hastigheter, vilket innebär att det finns sekundära flöden i planet vinkelrätt mot strömriktningen. Den radiella hastigheten är cirka 16 % av den strömvisa hastigheten. På grund av närvaron av sekundärt flöde lutar tvärflödet över enskilda rör och lutningsriktningen ändras vid olika omkretspositioner. Vid samma perifera position är flödesinklinationsriktningen densamma längs strömriktningen och radiell riktning. För spiralformade rörknippen är förhållandet mellan blockeringsarean och flödesarean (blockeringsareaförhållandet) för de inre, yttre och mellersta flödesvägarna olika. Blockeringsareaförhållandet för den inre flödesvägen är stort och blockeringsareaförhållandet för den yttre flödesvägen är litet, vilket resulterar i ojämn hastighetsfördelning i olika flödesvägar.Tvärflöde över spiralformade rörknippen med tre spiralformade diametrar (innerväggsradien Ri är 0,02 m, 0,14 m respektive 0,26 m) simuleras. För rörknippe med liten spiraldiameter (Ri = 0,02 m) är den maximala strömhastighetsolikformigheten 16,6 %. För rörknippen med mellersta och stora spiralformade diametrar (Ri = 0,14 m och 0,26 m) är den maximala strömhastighetsolikformigheten 6,7 % respektive 5,8 %. Resultaten visar att flödesojämnheten blir mer uppenbar för små spiralformade diametrar.De bärande strukturerna resulterar i mer komplexa sekundärflöden. Sekundärflödena långt från stödkonstruktionerna är större än de i området nära stödkonstruktionerna. De bärande strukturerna gör att blockeringsareaförhållandet för inre, yttre och mellersta flödesvägar varierar med den spiralformade diametern, och blockeringsareaförhållandets ojämnhet är större än utan stödkonstruktioner. I närvaro av stödkonstruktioner är de maximala strömhastighetsojämnheterna för små, mellersta och stora spiralformade rörknippen 22,0 %, 8,8 % respektive 6,3 %. Effekten av stödkonstruktioner på flödesojämnheten ökar när den spiralformade diametern minskar.

International Telemetering Conference Proceedings / October 26-29, 1992 / Town and Country Hotel and Convention Center, San Diego, California / In recent years, many designers have turned to digital techniques as a means of improving the fidelity of instrumentation data recorders. However, single and multi-channel recorders based on professional VHS transports are now available which use innovative methods for achieving near-perfect timebase accuracy, inter-channel timing and group delay specifications for long-duration wideband analog recording applications. This paper discusses some of the interesting technical problems involved and demonstrates that VHS cassette recorders are now a convenient and low cost proposition for high precision multi-channel wideband data recording.

Thesis (PhD)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Hierarchical information transfer is investigated as a tool to prepare well‐defined nanostructures with high aspect ratios, via the self‐assembly of helically folding poly(paraaryltriazole) (P(p‐AT)) foldamers. A novel ‘helicity codon’ based on the 1,4‐linkage geometry in 1,4‐aryl‐disubstituted‐1,2,3‐ triazoles is developed. Helical folding is induced exclusively by directing all triazole moieties into a cisoid configuration. By linking the triazole rings in a para fashion about the aryl moiety, this helicity codon codes for a helix with a large internal cavity of ~ 3 nm. One turn of the putative helical conformation requires 14 repeat units and the helical pitch is ~ 0.38 nm. The aryltriazole backbone is appended with amphiphilic oligo(ethylene glycol) (oEG) units which have the dual roles of imparting solubility as well as instigating a solvophobic helical folding in solvents which poorly solvate the hydrophobic arytriazole backbone but, solvate the side chains fully. The helix interior is hydrophobic and the exterior is amphiphilic. A true polymer synthesis approach to the foldamer synthesis, based on the copper catalysed azide‐alkyne cycloaddition (CuAAC) AB step growth polymerization system, is developed. This is preceded by a facile synthetic protocol for the AB monomers. The subsequent P(p‐ AT)s have high molecular weights ensuring several turns in the helical foldamer. A DMF/H2O good solvent/bad solvent system is established. Twist sense bias in the helical foldamers is successfully imparted by installing enantiopure chiral oEG side chains. Spectroscopic signatures for the solvent dependent coil to helix transition are established enabling the tracking of the conformational transitions from primary to secondary and finally tertiary structure. Conclusive evidence for the formation of stable, long stacked helical columns, in the solution state, is provided via cryo‐TEM. The helical stacks are several microns long, but of random lengths and do not intertwine but rather run parallel to each other. The helical stacks, however, have indeterminate lengths. Control over the length and chirality of the self‐assembled helical stacks is successfully imparted by using a template which mimics the role of ribonucleic acid (RNA) in tobacco mosaic virus (TMV). The template used is the hydrophobic α‐helical polypeptide poly(γ‐ benzyl‐L‐glutamate) (PBLG). Self‐assembly is driven by solvophobicity in a DMF/H2O system, the PBLG template being encapsulated inside the hydrophobic cavities of the stacked/selfassembled helical foldamers. Information from the template, i.e. length and chirality, is used to control the length and the chirality of the stacked/self‐assembled construct. The templated self‐assembly process is solvent dependent. When carried out in the solvent regime at the coil to helix transition mid‐point of the foldamer host, system operates under a dynamic equilibrium. Under these conditions, the self‐assembly process is shown to take place between two distinct states, the foldamer helices and the helical template, the template threading through the foldamer helices. The resulting self‐assembled construct has a pseudo‐rotaxane architecture. Under dynamic equilibrium conditions, temperature induced dis‐assembly of the templated assembled construct, is shown to be a cooperative process, whilst re‐assembly is characterized by a large hysteresis. By increasing the volume fraction of water, the solvophobic character of the system is increased and template assembled construct is better stabilised. The assembly system, however, loses its dynamic equilibrium character and falls into kinetic traps. Temperature induced de‐threading, of the foldamer helices, becomes less favourable and loses its cooperative character although the hysteresis loop is reduced. / AFRIKAANSE OPSOMMING: Hiërargiese inligtingsoordrag is bestudeer as ‘n hulpmiddel om goed gedefinieerde nanostrukture met ‘n goeie beeldverhouding voor te berei. Die nanostrukture word voorberei deur middel van self‐samestelling van heliese vouing van poli(para‐arieltriasool) (P(p‐AT)) ‘foldamers’. ‘n Nuwe heliese‐kodon gebaseer op die 1,4 koppelingsgeometrie in 1,4 arieldigesubstitueerde‐ 1,2,3‐triasool is ontwikkel. Heliese vouing word uitsluitlik geïnduseer as al die triasole in die sis konfigurasie is. Deur die triasole in ‘n para konfigurasie te bind, kodeer die heliese kodon vir ‘n heliks met ‘n groot interne kanaal van ~ 3 nm. Een draai van die heliks benodig 14 herhalende eenhede en die heliese gradiënt ~ 0.38 nm. Amfifiliese oligo(etileen glikol) (oEG) eenhede is aan die arieltriasoolruggraat aangeheg. Hierdie aanhegting van oEG eenhede bevorder oplosbaarheid en dit induseer ‘n solvofobiese heliese vouing in oplosmiddels wat nie die hidrofobiese arieltriasoolruggraat oplos nie, maar wel die sy‐kettings volledig oplos. Die binnekant van die heliks is hidrofobies en die buitekant is amfifilies. ‘n Polimeersintese benadering tot die ‘foldamer’ sintese (gebaseer op die koper gekataliseerde siklo‐addisie reaksie tussen ‘n asied en ‘n alkyn) AB stapsgewyse groei polimerisasiestelsel, is ontwikkel. Dit is voorafgegaan deur ‘n geskikte sintetiese protokol vir die AB monomere. Die daaropvolgende P(p‐AT) het ‘n hoë molekulêre massa wat verseker dat daar ‘n hele paar draaie in die heliese ‘foldamer’ is. ‘n DMF/H2O goeie oplosmiddel/ swak oplosmiddel sisteem is vasgestel. Draaiing van die heliks na ‘n spesifieke kant alleenlik is suksesvol geïnduseer deur die toevoeging van suiwer enantiomere van die chirale oEG sykettings. Spektroskopiese handtekeninge van die oplosmiddel‐afhanklike ketting tot heliks transformasie word vasgestel sodat die oorgangstoestande gevolg kan word vanaf primêre tot sekondêre en uiteindelik tesiêre struktuur. Beslissende bewyse vir die formasie van stabiele, lang gestapelde heliese kolomme in die opgeloste toestand is bewys met cryo‐TEM. Die heliese stapels is verskeie mikron lank, maar het verskillende lengtes. Die heliese stapels is parallel aan mekaar en oorvleuel nie. Die lengte van die heliese stapels is egter onbepaalbaar. Beheer oor die lengte en chiraliteit van die self‐samestellende heliese stapels is verkry deur gebruik te maak van ‘n templaat wat die rol van ribonukleïensuur (RNS) in die tabakmosaïekvirus (TMV) naboots. Hidrofobiese α‐heliese polipeptied poli(γ‐bensiel‐Lglutamaat) (PBLG) is gebruik as die templaat. Self‐samestelling word gedryf deur solvofobisiteit in ‘n DMF/H2O stelsel, met die PBLG templaat wat dan geënkapsuleer word binne die hidrofobiese holtes van die gestapelde/ self‐saamgestelde heliese ‘foldamers’. Die lengte en die chiraliteit van die templaat word gebruik om die lengte en chiraliteit van die gestapelde helikse te beheer. Die templaatbemiddelde self‐samestellende proses is afhanklik van die oplosmiddel. Die stelsel is by ‘n dinamiese ewewig wanneer, uitgevoer in ‘n oplosmiddel, die ketting na heliks oorgang die middelpunt van die ‘foldamer’ gasheer bereik het. By hierdie omstandighede vind die self‐samestellende proses plaas tussen twee afsonderlike toestande nl. die ‘foldamer’ helikse en die heliese templaat, en die templaat wat vleg deur die ‘foldamer’ helikse vleg. Die gevolglike struktuur het ‘n pseudo‐rotaxane argitektuur. By dinamiese ewewigstoestande veroorsaak temperatuur dat die self‐samestellende templaatstrukture weer disintegreer. Hierdie is ‘n koöperatiewe proses terwyl die hersamestelling gekarakteriseer word deur ‘n sloerende proses. Deur die waterfraksie te vermeerder, word die solvofobiese karakter van die sisteem verhoog en die templaat selfsamestellende struktuur beter gestabiliseer. Die samestellingsproses verloor egter sy dinamiese ewewigkarakter en val in kinetiese slaggate. Temperatuur geïnduseerde disintegrasie van die foldamer helikse word minder gunstig en dit verloor die koöperatiewe karakter alhoewel die sloering verminder is.

As estacas helicoidais têm sido empregadas em diversos tipos de obras no Brasil e no mundo, principalmente em casos em que a fundação é submetida a carregamentos simultâneos de tração e de compressão ou que necessitam de rápida e facilitada instalação. O maior uso nacional é em fundações de torres de linhas de transmissão de energia, no entanto, são escassos os estudos do comportamento deste tipo de estaca em solos tropicais brasileiros. Considerando-se o crescimento do uso de estacas helicoidais no Brasil, e a necessidade de um melhor entendimento do comportamento deste tipo de fundação em nossos solos, o presente trabalho foi realizado para verificar a influência do arranjo das hélices, tanto do diâmetro quanto da quantidade, na capacidade de carga à tração das estacas helicoidais multi-hélices, instaladas em solo tropical da região de São Carlos, na cidade de Itirapina próxima a lagoa do Broa. A campanha de investigações geotécnicas foi composta por sondagens de simples reconhecimento (SPT) e ensaios de cone (CPT). Foram ensaiadas nove estacas, com diferentes configurações de diâmetro e de número de hélices, instaladas com a ponta em mesma profundidade, mesmo espaçamento entre hélices (igual a três vezes o maior diâmetro) e mesmo diâmetro de haste. Nesta investigação foram medidos os torques de instalação, e realizadas provas de cargas à tração do tipo estática com carregamento rápido. Como conclusões, o atrito lateral obtido com o ensaio CPT foi útil para verificar o efeito de perda de resistência do solo com a instalação da estaca; o método de capacidades de carga individuais obteve estimativas mais próximas as medidas em prova de carga; o efeito da configuração (cônicas ou cilíndricas) influencia no torque de instalação, mas não na capacidade de carga das estacas; o acréscimo de diâmetro médio das estacas é interessante para acréscimos na capacidade de carga, no entanto o acréscimo do número de hélices, a hélice superior sempre absorve menores cargas do que a hélice da ponta da estaca. / The helical piles have been used in different types of constructions, especially in cases where the foundation is subjected to tension and compression loads. In Brazil, this type of pile is normally used as the foundation of towers of power transmission lines, as guyed masts and self-supporting towers. However, there are few studies about the behavior of helical piles in Brazilian tropical soils. Considering the growing use of helical piles in Brazil, and the need of a better understanding of the behavior of this type of foundation in our soils, this study was conducted to evaluate the influence of the arrangement of the helices on the uplift capacity of helical piles installed in the tropical soil of São Carlos zone of São Paulo State. For this study, geotechnical investigations were carried out: standard penetration tests (SPT) and cone tests (CPT). Nine piles with different configurations (diameter and number of blades) were tested after being installed with the tip at the same final depth into the ground, and the same relative helix spacing (S/D>3). For this investigation, the torque necessary to install the piles were recorded, and subsequently static tensile loads tests were performed on all piles. As results: the lateral friction obtained with the CPT test was useful to check the effect of losing soil strength with the installation of the screw pile, the individual bearing method obtained estimates closer measurements in load test then cylindrical shear method; the effect of configuration (conical or cylindrical) influences on the torque installation, but not the uplift capacity of the screw piles, increases in the size of average diameter of helix in screw piles make increases in uplift capacity, however the increase in the number of helix did not appear as good as increases in the average diameter of the helix.

A técnica da fotoelasticidade pode ser particularmente útil na análise de tensões em sistemas com geometrias complexas. Em um equipamento chamado polariscópio, um feixe de luz polarizada atravessa o modelo fotoelástico que representa o protótipo. Ao submeter este modelo a um carregamento, faixas de diferentes cores poderão ser visualizadas. Cada cor é associada a um nível de tensão. As tensões observadas no modelo fotoelástico podem ser comparadas com as tensões determinadas nos modelos numéricos ou analíticos. Em casos específicos, o problema da distribuição de tensões em uma fundação pode ser analisado com emprego da fotoelasticidade. A análise do comportamento de estacas helicoidais através da técnica da fotoelasticidade pode ser então de grande valia para estudos mais aprofundados deste sistema. O principal objetivo desta pesquisa foi viabilizar este método experimental para ser aplicado no Departamento de Geotecnia da EESC em análises de tensões em sistemas geotécnicos. Para validar as análises experimentais, tensões observadas em modelos de geometria simples foram comparadas com as tensões determinadas por meio de modelagem numérica com o método dos elementos finitos. O comportamento da fundação por estaca helicoidal observado pela técnica da fotoelasticidade mostrou semelhança ao observado na modelagem numérica. Por meio da distribuição de tensões, foi possível avaliar a influência da geometria helicoidal da lâmina e da profundidade de instalação da ancoragem no terreno. / The photoelastic method can be particularly useful for stress analysis with complex geometry systems. In equipment called polariscope, a polarized light beam crosses the photoelastic model that represents the prototype. Submitting this model to a load, fringes of different colors can be visualized. Each color is associated to a stress level. The stresses corresponding to the observed fringes on the photoelastic model can be compared to the stresses obtained through analytical or numerical models. In specific cases, the stress distribution problem can be analyzed with the use of photoelasticity. The photoelastic analysis of the helical pile behavior can then be valuable for further studies of this system. The main objective of this research was enabling this experimental method to be applied in the Department of Geotechnical Engineering of EESC in geotechnical systems stress analysis. To validate the experimental analysis, stresses observed in simple geometry models have been compared to those stresses determined by numerical modeling with the finite element method. The observed behavior of the helical pile foundation by photoelastic method showed similarity to that one observed through numerical modeling. Stress distribution analyses allowed evaluating the influence of helical blade geometry and the depth of installation.

Algumas serpentes necessitam obrigatoriamente estocar espermatozoides nos ovidutos para que os oócitos sejam fecundados, isso porque nessas espécies o período de cópula é distinto do período de ovulação. Em geral essa estocagem ocorre em receptáculos de estocagem encontrados na região infundibular. Em Crotalíneos a estocagem tem sido descrita como ocorrendo na região caudal dos ovidutos (junção útero-vaginal) em uma estrutura chamada de Uterine Muscular Twisting (UMT). Essa estrutura tem sido descrita como um twisting que se forma após a cópula e permanece presente até o momento da ovulação. Aqui demonstramos que a UMT não é formado por uma torção (twist) do oviduto e sim por uma helicoide formada pelas camadas internas da junção útero-vaginal. A UMT está presente em fêmeas ao longo de todo o ano, e não somente no período pós-cópula. Nós observamos que a UMT tem diferentes graus de formação, podendo ser forte, fraca ou ausente. A UMT forte é encontrada no periodo reprodutivo da fêmea (outono e inverno austrais) e está presente independentemente de haver espermatozoides nessa região. A UMT fraca é encontrada em todas as fêmeas maduras fora do período reprodutivo. Já a ausencia de UMT é encontrada nas fêmeas prenhes e nas imaturas. Nossos resultados mostram que a UMT é formada mesmo em fêmeas ovariectomizadas com níveis basais de estradiol e que a progesterona é responsável pelo relaxamento da musculatura lisa do oviduto tornando a UMT ausente nas fêmeas / Some snakes need must store sperm in the oviduct so that the oocytes are fertilized, that because these species the mating period is distinct from ovulation period. Usually this occurs in receptacles found in the infundibular region. In pitvipers the storage has been described as occurring in the caudal region of oviduct (uterus-vaginal junction) in a structure named Uterine Muscular Twisting (UMT). This structure has been described as a twisting formed after mating and remains present until the time of ovulation. Here we demonstrate that the UMT is not formed by a twist (rotation around its own axis) of the oviduct but by a helicoid formed by the inner layers of the uterus-vaginal junction. The UMT is present in females throughout the whole year, not only in the post-copulation period. We note that the UMT has different degrees of shaping, can be strong, weak or absent. Strong UMT is found in the female reproductive period (austral autumn and winter) and is present regardless of whether sperm cells in this region. Weak UMT is found in all mature females outside the breeding season. Already the absence of UMT is found in pregnant females and the immature ones. Our results show that the UMT is formed even in ovariectomized with basal levels of estradiol and progesterone is responsible for relaxation of smooth muscle of the oviduct making UMT absent in females

O trajeto do canal da mandíbula é oblíquo com sentido póstero-anterior, apresenta-se próximo da cortical óssea alveolar medial, até atingir a face mesial do primeiro molar inferior, a partir desta região aproxima-se da lâmina óssea alveolar lateral até alcançar o forame mentual. Radiograficamente, o canal da mandíbula se apresenta, como uma linha radiolúcida delimitada por duas linhas radiopacas. Existem diversos métodos de exames radiográficos que possibilitem a avaliação do complexo maxilo-mandibular. Estudos mostram que a Tomografia Computadorizada (TC) foi considerado o melhor método para a avaliação do trajeto no sentido vestíbulo-lingual do canal da mandíbula. Foi proposto analisar a morfologia no sentido vestíbulo-lingual das variações do trajeto do canal da mandíbula em imagens de TC utilizando o software Dental Slice®. Com a ferramenta mensuração deste software , avaliou-se 100 TC bilateralmente, criando-se três retas. Uma horizontal (vestíbulo-lingual), dividindo o canal ao meio, e duas retas verticais, tangenciando a face externa lingual e vestibular da cortical do canal. Para análise dos dados utilizou os testes de normalidade, teste de hipótese (teste t e ANOVA) e teste de aderência Anderson Darling. Concluiu-se que existe uma tendência da presença de pouca variabilidade, entre os lados direito e esquerdo; a porção do canal mais próxima ao forame mentual apresenta-se vestibularizado, e na região posterior lingualizado; há necessidade da avaliação topográfica do canal da mandíbula por meio da Tomografia Computadorizada. / The course of the mandibles canal is oblique with posterior-anterior direction, it comes close to the medial cortical alveolar bony, until reaching the mesial face of the first inferior molar, starting from this area, it approaches of the lateral cortical alveolar bony until reaching the forame mentual. Radiographically, the manbible´s canal comes, as a radiolucent line defined by two radiopaque lines. Several methods of exams radiographyc that facilitate the evaluation of the complex maxilo-mandibular. Studies show that the Computerized Tomography (TC) is the best method for consider the evaluation of the course in the vestibule-lingual direction of the mandibles canal. It was intended to analyze the morphology in the vestibule-lingual direction of the variations of the course the mandibles canal in images of TC using the Dental Slice® software. With the mensuration tool of this software, 100 TC was evaluated bilaterally, being created three straight line. A horizontal one (vestibule-lingual), dividing the canal in the middle, and two vertical straight line, being tangent to the lingual external face and vestibular of the canals cortical. For analysis of the data it used the normality tests, hypothesis test (tests t and ANOVA) and test of adherence Anderson Darling. It conclude that a tendency exists the presence of little variability, among the sides right and left. The canal close to the forame mentual presents vestibular direction, and in the posterior area on lingual direction. And Confirm the need of the use of TC in the topographical evaluation of the mandibles canal.

Na prática brasileira, usualmente a previsão da capacidade de carga de fundações por estacas é baseada em métodos semi-empíricos, por meio de correlações diretas da resistência de ponta e por atrito lateral ao longo da estaca com os valores de NSPT. Entretanto, no caso de fundações por estacas helicoidais, ainda utilizam-se métodos teóricos que necessitam de valores de parâmetros geotécnicos obtidos indiretamente a partir de correlações com os valores de NSPT (coesão, peso específico, ângulo de atrito, coeficiente de empuxo). Portanto, nesta dissertação foi desenvolvido um método semi-empírico para estimar a capacidade de carga à tração de fundações por estacas helicoidais profundas por meio de correlações diretas com o valor de NSPT do solo de instalação da estaca. Além disso, são apresentados no presente trabalho valores de fator de torque KT, obtidos por análise estatística, para a verificação da capacidade de carga à tração da estaca usando-se medidas do torque necessário para instalá-la no terreno. Nesta pesquisa dois diferentes modelos para estimativa da capacidade de carga foram desenvolvidos e analisados estatisticamente. O estudo das características das amostras de fundações por estacas helicoidais usadas nesta pesquisa permitiu a subdivisão em grupos (tipo de solo e quantidade de hélices) de modo a se obter modelos mais precisos. Com os resultados deste trabalho, foi possível elaborar recomendações para projeto e execução de estacas helicoidais, bem como desenvolver um modelo para estimar a capacidade de carga à tração de estacas helicoidais instaladas em solos similares aos das estacas usadas neste estudo. / The pile capacity in Brazil is usually predicted by semi-empirical methods based on direct correlations between SPT-N values and pile shaft and pile base resistance. However, the uplift capacity of helical piles is still calculated using theoretical methods based on soil parameters, as: cohesion, unit weight, friction angle, and lateral earth pressure coefficient. In this case, these parameters are obtained indirectly from correlations with values of SPT-N. This dissertation was inspired by the need of a more appropriate method to calculate the uplift capacity of helical piles, by correlating the capacity of the bearing plates directly with the soil type and SPT-N values. In this work, it was developed a semi-empirical method for estimating the pullout capacity of deep helical piles by using SPT test results, similarly to the other methods used for conventional piles. Also, this work presents some results of torque factor, obtained by statistical analysis, to the verification of the pile capacity by using the torque recorded at the end of pile installation. In this research, it was performed several statistical analysis to obtain appropriate models to estimate the uplift capacity of helical piles. The cases of helical piles used in this investigation are classified into groups according to the soil type and the number of helices. As a result, detailed evaluations and recommendations for improvement of helical pile design are presented. The proposed model is recommended to calculate the uplift capacity of helical piles installed in similar soils to that used in this study.