FINITE ELEMENT FATIGUE ASSESSMENT OF STEEL TUBULAR JOINTS IN OFFSHORE STRUCTURES

Background: Fatigue analysis is a very complex process, which is still today not fully under-stood. This thesis numerically investigates the advantages and limitations of the employment of the Finite Element (FE) method in actual standard fatigue design procedure. Two studies are conducted to validate the SCF calculation and the application of Hot-Spot Stress (HSS) method to fatigue design. Study I: The Stress Concentration Factor is a magnification factor introduced to account for geometrical or material discontinuities in structural joints. In these locations the stress may reach values several times higher than the nominal stress and may lead to the premature collapse of the structure when subjected to fatigue loading. However, current methodologies to compute the SCF cover only a limited number of joint types and configurations. The aim of this study is to investigate the SCFs in tubular joints through the application of empirical formulas and an extensive numerical analysis campaign. SCFs are assessed for several types of tubular joints and loading conditions according to current standards and literature. Obtained results are compared together to highlights the weaknesses and strengths of each approach and to investigate their implications for the design of tubular joints. Study II: Fatigue is one of the most frequent causes of steel structures failures, particularly in offshore platforms. Thus, the fatigue life assessment is one of the most relevant procedures for the comprehensive evaluation of both the load-carrying capacity and service life of the structure. The standard fatigue procedure consists of the method of local stress, the so-called Hot-Spot Stress (HSS) applied on a global analysis model. HSS method consists in calculating the stress occurring in the cross sections of the whole elements and applying them a multiplying factor to account for the geometry of the detail. At present, the use of Finite Element makes possible looking for more accurate fatigue stress ranges calculation. This study presents fatigue assessment of representative types of tubular joints in welded offshore platform. Joint fatigue damages are calculated performing global and local FE analyses. The obtained results are com-pared together to evaluate the limits and advantages of the different approaches and model types

On the Interactions of Augmin with Microtubules and the Mechanics of the Cross-Linker PRC1

Cell division in eukaryotes requires the assembly and maintenance of a structure, the bipolar spindle, self-organized from microtubules and their associated proteins. A multitude of components have been identified to be involved in this organization, and solving the combinatorial of the conditions that lead to the specific set of configurations present in vivo remains an open question. This thesis presents reconstitutions from purified components used to study aspects of microtubule self-organization: first, the microtubule-nucleation-related augmin octameric complex was assessed at a single-molecule interaction level with microtubules; second, the cross-linker PRC1\u27s frictional response resisting motion between two microtubule filaments was analyzed to determine the dependence of the frictional force on the binding conditions of the cross-linker. For the augmin complexes studied sub-second interaction times were observed, yielding diffusive tracks on the lattice of microtubules. Microtubule bundles driven to slide showed GFP-PRC1 accumulation with a near-contant frictional force recorded. From the data, a theoretical model was produced linking the accumulation of GFP-PRC1 to the time evolution of the force trace. The observations on the reconstituted augmin complex establish constrains (diffusive and short lived) on an entity proposed to anchor newly-nucleated microtubules to pre-existing microtubules at a given branching angle. The observations on PRC1 mechanics lead to the hypothesis of a changing mechanical behavior of the cross-linker to its exchange kinetics, potentially modulated by external factors

Developing a new business model for enabling research - the case of the ACPFG in Australia

Publisher's postprint archived as permitted by publisher.The way in which companies, research centres and educational institutions are organised and structured may provide a competitive advantage for commercialisation, in particular if companies are dependent on the deployment of complementary assets and capabilities by third parties. This paper presents the case of the Australian Centre for Plant Functional Genomics (ACPFG), a private agricultural biotechnology (agbiotech) company specialising in early stage Research and Development (R&D) to produce superior adapted cereal varieties, tolerant to abiotic stress conditions such as drought, frost, salt, or mineral toxicity, all of which have a direct and negative impact on plant growth and crop productivity. The organisational structure of the company has been influenced and shaped by Government policy, shareholders expectations and trends in the agbiotech industrial organisation. It has proved attractive to potential alliance partners for collaborative R&D and commercialisation. We present the ACPFG as a new business model to fund basic research and facilitate technology transfer.Stephanie C. Agius, David Corkindale, Antonio G. Dottore, Michael Gilber

Fostering Futures in Virginia: Why Is It Needed and What Does It Add to Existing Programs?

This article addresses the large population of foster children over the age of 13 who have the same need for stable outcomes as younger foster children. Older foster children face a greater challenge in achieving a stable outcome because of their age. With this challenge comes a greater likelihood of homelessness and involvement in the criminal justice system. This article examines the various programs in Virginia designed to address the challenges faced by older foster children, and particularly, a new program called Fostering Futures, which provides greater support specifically to older foster children

Soft Legged Wheel-Based Robot with Terrestrial Locomotion Abilities

In recent years robotics has been influenced by a new approach, soft-robotics, bringing the idea that safe interaction with user and more adaptation to the environment can be achieved by exploiting easily deformable materials and flexible components in the structure of robots. In 2016, the soft-robotics community has promoted a new robotics challenge, named RoboSoft Grand Challenge, with the aim of bringing together different opinions on the usefulness and applicability of softness and compliancy in robotics. In this paper we describe the design and implementation of a terrestrial robot based on two soft legged wheels. The tasks predefined by the challenge were set as targets in the robot design, which finally succeeded to accomplish all the tasks. The wheels of the robot can passively climb over stairs and adapt to slippery grounds using two soft legs embedded in their structure. The soft legs, fabricated by integration of soft and rigid materials and mounted on the circumference of a conventional wheel, succeed to enhance its functionality and easily adapt to unknown grounds. The robot has a semi stiff tail that helps in the stabilization and climbing of stairs. An active wheel is embedded at the extremity of the tail in order to increase the robot maneuverability in narrow environments. Moreover two parallelogram linkages let the robot to reconfigure and shrink its size allowing entering inside gates smaller than its initial dimensions

Large-scale submarine landslide drives long-lasting regime shift in slope sediment deposition

Submarine landslides and associated mass-transport deposits (MTDs) modify the physiography of continental margins and influence the evolution of submarine sediment routing systems. Previous studies highlighted the control of landslides and MTDs on subsequent sedimentary processes and deposits at spatial scales ranging from tens of centimeters to few kilometers, leaving a knowledge gap on how and for how long large-scale submarine landslides (i.e., headscarps wider than 50–100 km) may affect the stratigraphic evolution of continental margins. To fill this gap, we used three-dimensional seismic reflection data tied to an exploration well to investigate the impact of one of the largest submarine landslides discovered on Earth, the Mafia mega-slide (Mms) offshore Tanzania, on slope sediment deposition. Seismic data interpretation indicates that turbidite lobes/lobe complexes and coalescent mixed turbidite-contourite systems formed the pre-Mms stratigraphy between 38 and ca. 21 Ma (age of the Mms), whereas coarser-grained sheet turbidites and debrites accumulated after the Mms for ∼15 m.y., primarily on the topographic lows generated by the emplacement of the landslide. We interpret this drastic and long-lasting regime shift in sediment deposition to be driven by the increase in seafloor gradient and the capture and focus of feeding systems within the broad failed area. We propose that the extensive evacuation zones associated with such giant landslides can generate major “conveyor belts”, trapping land-derived material or sediments transported by along-slope processes such as bottom currents. During the progressive healing of the landslide escarpments, which may last for several million years, sand-prone facies are deposited primarily in the upper slope, filling up the accommodation space generated by the landslide, while deeper-water environments likely remain sediment starved or experience accumulation of finer-grained deposits. Our study provides new insights into the long-term response of slope depositional systems to large-scale submarine landslides, with implications for the transfer of coarse-grained sediments that can be applied to continental margins worldwide

Tecniche di segmentazione di immagini di fondali marini per la mappatura della Posidonia oceanica

Implementazione di un sistema automatico di riconoscimento di immagini, per l'identificazione della presenza della Posidonia oceanica tramite la costruzione di un modello del pattern e ricerca del classificatore

Nuove sperimentazioni in vitro sulla terapia dell'oftalmopatia basedowiana

Nuove sperimentazioni in vitro sulla terapia dell'oftalmopatia basedowiana L’oftalmopatia basedowiana (OB) è una sindrome autoimmune caratteristicamente associata alle malattie autoimmuni della tiroide, in particolare al morbo di Basedow. L’OB è caratterizzata da una proliferazione incontrollata dei fibroblasti orbitari e da una aumentata produzione di glicosaminoglicani, in particolare acido ialuronico (HA). La terapia della OB grave è basata sull’uso di glucocorticoidi ad alte dosi. Nella OB lieve, invece, non ci sono terapie disponibili standardizzate e l’uso di glucocorticoidi ad alte dosi non è giustificato a causa del cattivo rapporto benefici/effetti collaterali. Per questo motivo sono in via di sperimentazione nuove terapie che prevedano l’impiego di farmaci possibilmente privi di effetti collaterali rilevanti. La presente tesi riporta i risultati di studi in vitro finalizzati a valutare l’effetto di alcuni farmaci potenzialmente candidati, su colture primarie di fibroblasti orbitari provenienti da pazienti con OB e da soggetti senza OB. I farmaci in questione sono: 1) Quercetina, un flavonoide con proprietà anti-ossidanti. A questo proposito si segnala che lo stress ossidativo è uno dei meccanismi implicati nella patogenesi dell’OB e che è stato precedentemente dimostrato un effetto anti-proliferativo della quercetina su fibroblasti di altra origine. 2) Enalapril, un farmaco anti-ipertensivo che è stato dimostrato avere un effetto anti-proliferativo su fibroblasti di altra origine, possibilmente dovuto ad una attività inbitoria del TGF- β , una citochina coinvolta nella sintesi di HA. 3) Selenio, una molecola con proprietà anti-ossidanti che è già stata dimostrata essere efficace nella terapia della OB lieve. I risultati hanno mostrato una azione anti-proliferativa sui fibroblasti orbitari da parte della quercetina e dell’enalapril, con inibizione della produzione di HA. Il trattamento con selenio dei fibroblasti ha determinato un aumento della vitalità cellulare, precedentemente ridotta da stress ossidativo, e sono in corso ulteriori studi volti a caratterizzare i meccanismi responsabili di questa osservazione. Tali risultati, sia pur preliminari, pongono le basi per un possibile impiego delle suddette sostanze nella pratica clinic

Antenna sunshield membrane

An RF-transparent sunshield membrane covers an antenna reflector such as a parabolic dish. The blanket includes a single dielectric sheet of polyimide film 1/2-mil thick. The surface of the film facing away from the reflector is coated with a transparent electrically conductive coating such as vapor-deposited indium-tin oxide. The surface of the film facing the reflector is reinforced by an adhesively attached polyester or glass mesh, which in turn is coated with a white paint. In a particular embodiment of the invention, polyurethane paint is used. In another embodiment of the invention, a layer of paint primer is applied to the mesh under a silicone paint, and the silicone paint is cured after application for several days at room temperature to enhance adhesion to the primer

SIMBA: Tendon-Driven Modular Continuum Arm with Soft Reconfigurable Gripper

In this paper, we describe the conceptual design and implementation of the Soft Compliant Manipulator for Broad Applications (SIMBA) manipulator, which is designed and developed for participating in the RoboSoft Grand Challenge 2016. In our novel design, we have proposed (1) a modular continuum arm with independent actuation units for each module, to increase maintainability; (2) a soft reconfigurable hand, for a better adaptation of the fingers to objects of different shapes and size; (3) a moving base for increasing the workspace. We used a hybrid approach in designing and manufacturing by integrating soft and hard components, in both materials and actuation, providing high lateral stiffness in the arm through flat springs, soft joints in fingers for more compliancy and tendon-motor actuation mechanism providing flexibility but at the same time precision and speed. The SIMBA manipulator has demonstrated excellent grasping and manipulation capabilities by being able to grasp objects with different fragility, geometry, and size; and by lifting objects with up to 2 kg of weight it demonstrate also to be robust and reliable. The experimental results pointed out that our design and approach can lead to the realization of robots able to act in unknown and unstructured environments in synergy with humans, for a variety of applications where compliancy is fundamental, preserving robustness and safety