Academic literature on the topic 'Plan tension'

This study case comes from a large-scale comprehensive gymnasium that is under construction. It is a frame structure, and the total height is 23.5m, and the main beam in 2nd and 4th floor are post-tensioned bonded pre-stressed concrete structure with a longs span to 27m. As the thickness and the ration of steel bars of the bottom slab could not bear the load caused by construction and besides, before the terminal tension, the bracing to support the template could not be demolished to turnover; so, the plan that needs to tense from the upper floor to lower floor recurrently has not been adopted. Another construction process that proposes to tense the beams in one floor as soon as they are casted .However, Due to construction time limit and cost, this plan was not carried out. At last, we combining the two plans. In our plan, pre-stress tension and building construction were carried out simultaneously. According to accurate analysis of construction propose and flow, with careful check on main components, security, economics and building functions are uniformed together optimally.

In order to improve the characteristic and control strategy in transmission lines, a tension stringing mathematical model was established which analyzed the multiple disturbance factors of tension. According to the tension control principle of hydraulic system and the influence of different factors, a control method of constant tension adapted to the system was proposed based on pressure regulating plan. By simulation, the modified tension control system enhanced the dynamic response characteristic and stability effectively, which can realize the ideal constant tension control.

Dance therapy, after numerous researches, has proven to be a very beneficial exercise. We are considering reducing stress by applying an intervention plan based on a succession of specific dance steps, artistic program, made by entirely for this purpose. Our results show that the initial measurement, after the intervention program, students were able to greatly reduce mental tensions by further discharged their muscle tension. Certain indicators of stress can be improved by practicing a moment of sport dance with art therapy effect.

Da Lian gym is a typical elliptical inclined mega-grid suspend-dome structure. Its complex structure form makes the prestressing construction more difficulty, and it is necessary to make a reasonable choice of construction scheme. In the paper, the summary about traditional prestressing construction schemes is made, and the construction schemes of radial cable tension and strut lifting were compared with construction simulation technology and tensile test. the results indicates that both methods can achieve the prestress construction of the structure, while more difficulties were contained in strut lifting method, therefore construction schemes of radial cable tension was suggested in actual construction. The research can provide theoretical basis for the structure’s prestressed construction plan, and also provide reference for similar projects.

Critical construction process parameters and necessity of experimental study concerning tension stringing of large-section conductor are elaborated in this paper and in addition, test details related to critical process parameters of tension stringing construction is researched by citing the example of 1250mm2 large-section conductor, according to which test plan is worked out and test rack is designed.

Background. The impact of choice on consumer decision making is controversial in US health policy. Objective. The authors’ objective was to determine how choice set size influences decision making among Medicare beneficiaries choosing prescription drug plans. Methods. The authors randomly assigned members of an Internet-enabled panel age 65 and older to sets of prescription drug plans of varying sizes (2, 5, 10, and 16) and asked them to choose a plan. Respondents answered questions about the plan they chose, the choice set, and the decision process. The authors used ordered probit models to estimate the effect of choice set size on the study outcomes. Results. Both the benefits of choice, measured by whether the chosen plan is close to the ideal plan, and the costs, measured by whether the respondent found decision making difficult, increased with choice set size. Choice set size was not associated with the probability of enrolling in any plan. Conclusions. Medicare beneficiaries face a tension between not wanting to choose from too many options and feeling happier with an outcome when they have more alternatives. Interventions that reduce cognitive costs when choice sets are large may make this program more attractive to beneficiaries.

This article uses ethnographic and interview data to explore how halfway house and community corrections staff in a women’s halfway house in the northeastern region of the U.S. police women’s sexuality and the ensuing complications of being queer and under supervision. In this setting, women are required to create a Reentry Home Plan that is approved by Community Corrections Officers, putting into tension some women’s newly emerging queer identity and/or nonnormative relationship schema that they see as “healthier” and more stable than heterosexual relationships, with Probation or Parole Officers’ heteronormative ideals that disapprove nontraditional home plans. This study shows how these women negotiate a marginalized sexual identity and resist biased forms of heteronormative surveillance that extend beyond the legislative parameters of community corrections supervision. It also illustrates the tensions between correctional staff, who view residents’ nonnormative relationships as potential sources of risk, and the supervised women, as they develop community release plans.

This work presents the mathematical method to design complex trajectories for three-dimensional (3D) wells using spline in tension as coordinate functions. 3D spline-in-tension trajectories are obtained for various end conditions: free end, set end, free inclination/set azimuth, and set inclination/free azimuth. The resulting trajectories are smooth continuous functions which better suit the expected performance of modern rotary steerable deviation tools, in particular, point-the-bit and push-the-bit systems. A continuous and gradual change in path curvature and tool face results in the smoothest trajectory for 3D wells, which, in turn, results in lower torque, drag, and equipment wear. The degree of freedom and the associated parameters of the 3D curves express the commitment between the average curvature to the final length of the path that can be adjusted to fit the design requirements and to optimize the trajectory. Several numerical examples illustrate the various end conditions. This paper also presents the full mathematical expressions for the 3D path for four end conditions. The method is directly applicable to the well planning cycle as well as to automatic and manual hole steering’s. Spline-in-tension functions differ from the cubic functions in the extent that an additional parameter, which represent the “tension” of the curve, can be controlled. A totally “relaxed” curve is identical to a cubic curve, and as the tension increases a shorter curve length is obtained with a consequent effect in the curvature profile along the curve. In the limit, as the tension increases to infinite, the spline-in-tension approaches to a straight line. The tension offers an additional degree of freedom, which can be used to further optimize the final trajectory. The 3D spline-in-tension model provides the most versatile model to plan a 3D well trajectory to date. Suitable manipulation of the curve parameters, namely, L0, L1, and the three tensions, allows to give to the planned trajectory any desired behavior.

Au cours des dernières années, de nombreux concepts de structures spatiales dépliables ou gonflables constituées de membranes de grande dimension ont vu le jour. Cependant, les films minces de faible épaisseur utilisés dans ces réalisations se plissent lorsqu’ils sont soumis à des contraintes de compression. L’existence de plis sur ces surfaces peut affecter la performance de certains dispositifs jusqu’à les rendre totalement inutilisables. C’est la raison pour laquelle la prédiction de l’apparition des zones plissées et de leur géométrie est un axe de recherche important pour les acteurs de l’industrie spatiale. L’objectif de ces travaux est de proposer un ensemble d’outils permettant la simulation du plissement des films minces avec la méthode des éléments finis. La robustesse de nos procédures de calcul devra être évaluée en confrontant nos résultats numériques avec des données d’essai. La première partie de l’étude est consacrée à la constitution d’une base de données expérimentale en procédant au relevé de la forme des ondulations sur des éprouvettes bi-axiales soumises à des trajets de chargement variés. Ces mesures sont destinées à l’évaluation des procédures de prédiction des plis par la méthode des éléments finis. La faible épaisseur des films utilisés engendre des difficultés numériques qui nous ont amené à discrétiser ces structures avec des éléments finis coque sans degrés de liberté en rotation. Pour la résolution du problème de lambement de ces films minces, deux techniques ont été testées : la méthode d’analyse post-bifurcatoire et la minimisation de l’énergie potentielle totale avec l’algorithme de gradient conjugué<br>Over the past years there has been a large number of new structural concepts for large spacecraft applications involving stretched membranes. However, the membranes used in gossamer structures cannot undergo compressive stress because of their small bending stiffness. The result of compressive stress is that buckling occurs leading to membrane wrinkling. This may affect the performance and the reliability of the flexible gossamer structures. Thus, the prediction of wrinkle patterns in membrane surfaces is one of the many current technological interests in the aerospace industry. The main purpose of this work is to propose a method able to predict wrinkling of thin structures. The ability of the wrinkling procedures to do it has to be compared to experimental results. Firstly we present an experimental study of the wrinkle patterns that appear on flat membranes. Experiments were carried out on cruciform specimens stretched under in-plane uncoupled biaxial loads. Experimental data are used as validation cases for numerical procedures of wrinkling simulation with the finite element method. Because of the small thickness of membranes, the shell element behavior can present numerical locking mechanism. To avoid it, thin structures are discretized with rotation free shell elements. Then, to predict films wrinkling, two numerical methods were tested : post buckling analysis and minimization of the total potential energy using the conjugate gradient algorithm

This master’s research is a phenomenological inquiry into the pedagogical moment in teacher education. This phenomenon is explored through a conceptual lens that draws from the phenomenological pedagogical ideals that are intrinsic to the work of both Ted Aoki and Max van Manen. Following a comprehensive outline of the phenomenological methodology that guides this thesis, the pedagogical moment is described in terms of three phases: tension, opening and pulse. The phenomenon is further explored through several sub themes relating to the lifeworld existentials (time, body, space, relation to other). This research intertwines several phenomenological concepts (such as intentionality, embodiment, consciousness, pedagogy, and motion sensitive phenomenology), within the context of one “living” phenomenon as a way of shedding light on what it is like to experience a pedagogical moment from within the tensions of practicum teaching.

Ce travail est lié au système de protection des réseaux de distribution. Les réseaux radiaux dedistribution peuvent être protégés simplement par une protection placée en tête du départ. Maisl'exploitation future des réseaux de distribution, qui se transforment en réseaux intelligents,flexibles et adaptatifs, va sûrement nécessiter une protégeabilité plus complexe. Parconséquent, un nouveau plan de protection pourrait être nécessaire afin d'augmenter la fiabilitédu réseau de distribution et le taux de productions décentralisées. Il pourrait inclure plusieursprotections déployées sur un départ. Le but principal de ce travail est d'étudier comment lesprotections pourraient agir (sur quel genre de grandeurs les protections reposeront, quellecoordination faut-il choisir) et d'analyser les limites de ces nouvelles protections. En déployantplusieurs protections qui divisent le départ en des zones plus petites, le plan de protectionproposé, reposant sur une formulation modifié et optimisée, proche de celle des protections dedistance classiques, déconnectera ainsi moins de consommateurs et de producteurs lors del'apparition de défauts. Cela devrait réduire le temps de coupures brèves et de diminuerl'énergie non fournie. Ce manuscrit présente une solution pour les réseaux HTA radiaux faceaux défauts monophasés.

Pour de tres nombreux liquides, il existe une relation etroite entre la forme du streamer, sa vitesse de propagation, les courants et la lumiere emise quelque soit la polarite. Les vitesses augmentent par addition de composes capteurs d'electrons ou a bas potentiel d'ionisation. Pour des pressions et des pentes de rampe de tension elevees, les champs harmoniques de generation des streamers sont suffisants pour produire une emission ou ionisation de champ. On montre que les processus gazeux interviennent dans les deux polarites. L'analyse du bilan energetique indique que les mecanismes dominants sont la vaporisation pour les streamers lents et la dissociation et l'ionisation pour les streamers rapides, ce qui est confirme par chromatographie et spectroscopie d'emission

Apres avoir rappele le principe de la technique de croissance d'epitaxie par jets moleculaires, presentation d'un ensemble de caracterisations magneto-electriques (effet hall a bas champ magnetique, magneto-resistance et effet a fort champ magnetique), mais aussi des resultats purement electriques de c(v). Analyses par spectroscopie de masse d'ions secondes et mesures de double diffraction x. Tres bon accord entre ces resultats experimentaux et les investigations theoriques sur ces structures. Application de la technique a l'elaboration de dopages intenses, de contact ohmiques non allies et de transistors a effet de champ dont le canal est constitue par un dopage plan. Les performances presentees montrent les potentialites des dopages plan dans l'application a des structures de plus en plus sophistiquees

Ce travail concerne la modélisation de propriétés interfaciales d’alcanes linéaires confinés dans des pores plan/plan, telles que la quantité adsorbée ou la tension interfaciale par la simulation moléculaire de type Monte Carlo. Les calculs ont été réalisés dans les conditions thermodynamiques variées allant de pressions et températures très faibles jusqu’à des valeurs élevées rencontrées typiquement dans les réservoirs. Nous avons mené une étude de sensibilité concernant trois potentiels d’interaction classiquement utilisés, regardé l’influence du confinement géométrique et des conditions thermodynamiques sur le méthane confiné, calculé la chaleur isostérique d’adsorption et mis en évidence le phénomène de condensation capillaire. Les résultats d’isotherme d’adsorption obtenus par simulation ont été confrontés avec succès à des résultats expérimentaux. Cette comparaison a également permis de mettre en évidence l’importance de la caractérisation du milieu poreux lors de l’estimation de l’isotherme d’adsorption. Le comportement d’alcanes linéaires de plus longue chaine a également été étudié<br>This work concerns the modelling of interfacial properties of linear alkanes confined in slit pores, such as adsorbed quantities or interfacial tension by the Monte Carlo molecular simulation. The simulations were performed at various thermodynamic conditions ranging from very low pressures and temperatures to higher values typical of reservoirs. We have studied the influence of three classical interaction potentials, the effect of confinement and thermodynamic conditions on confined methane, the isosteric heat of adsorption and the phenomenon of capillary condensation. Adsorption isotherms obtained with Monte Carlo simulation were successfully compared with experimental results. This study has also underlined the impact of the porous media characterization on the estimation of adsorption. The behavior of alkanes with longer chains was also determined

Depuis le développement des composants d'électronique de puissance qui ont permis la fabrication d'onduleurs fiables et efficaces, les entraînements à vitesse variable utilisant des moteurs asynchrones sont devenus de plus en plus populaires. La technique MLI s'est avérée être une méthode très efficace de contrôle de la vitesse de rotation. Cependant, les impulsions de tension, avec des pentes très raides (de l'ordre de quelques kV/µs), ont apporté de nouveaux risques pour le système d'isolation électrique des moteurs. La richesse harmonique de la tension MLI entraînera une surtension significative due à une différence d'impédance entre le câble et le moteur. En effet, la tension observée par certaines parties du système d'isolation peut dépasser la tension d'apparition des décharges partielles (ang. PDIV); ce qui amorcera une activité de décharges partielles localisée. Le système d'isolation des machines basse tension (appelé type I) est basé presque entièrement sur des matériaux polymères qui ne sont pas conçus pour supporter des décharges partielles tout au long de leur vie. En raison de l'utilisation de variateurs de fréquence, l'isolation primaire du fil émaillée est en danger par rapport aux machines alimentées par réseau. En conséquence, c'est souvent le point le plus faible du système d'isolation qui conduira à la panne prématurée d'une machine. Le but de cette thèse est d'étudier et d'analyser le processus de vieillissement du fil émaillé exposé aux différents facteurs et de proposer une méthode permettant de prédire les durées de vie dans des conditions fixées. Cette étude introduit une prédiction basée sur la méthode des plans d'expériences et la distribution statistique de Weibull. Grâce au modèle obtenu avec des tests de vieillissement courts multicontraintes (température, tension, fréquence) il est possible de prédire les résultats de tests significativement plus longs. De plus, la méthodologie proposée permet de prédire la dispersion des essais longs en se basant sur la dispersion des résultats à court terme. Les prédictions sont comparées avec les données expérimentales afin de prouver la précision du modèle<br>Since the development of power electronic components, which allowed the manufacturing of reliable and efficient inverters, variable speed drives using inductive motors have become more and more popular. The PWM technique has proven to be a very effective method of rotational speed control. However, the fast changing voltage pulses, with very steep slopes (in the order of a few kV/µs), has brought new hazards for the electrical insulation system of such motors. Very high frequency harmonic components of PWM voltage will result in significant overvoltage due to an impedance mismatch between the cable and the motor. As an effect, the voltage seen by some parts of the insulation system may exceed the Partial Discharge Inception Voltage (PDIV) stating localized partial discharges activity. The insulation system in low-voltage machines (called type I) is based almost entirely on polymer materials, which are not able to support partial discharge activity throughout their lives. Due to the use of frequency inverters especially the primary insulation of the magnet wire is endangered in comparison with system-powered machines. As a result this is often the weakest link of the insulation system leading to a premature breakdown of the machine. The aim of this thesis is to investigate and analyze the aging process of the enameled wire exposed to different factors and to propose a method allowing to predict their lifespans in given conditions. This study introduces a prediction based on the Design of Experiments method and the statistical Weibull distribution. Thanks to the model obtained with short multi-stress (temperature, voltage, frequency) aging tests, it is possible to predict the results of significantly longer ones. Moreover, the adapted methodology is proposed that allows to predict the scatter of the long tests basing on the short-time results dispersion. The predictions are compared with the experimental data in order to prove the model accuracy

Confronté à un contexte de stagnation globale de la consommation d'électricité mais avec un potentiel important de développement de nouveaux usages, ainsi qu'à l'apparition d'unités de production dispersée sur le territoire, le principal gestionnaire de réseau de distribution français a besoin d'expliciter ce que sont ses grands choix de structure et de règles d'exploitation, et de les comparer avec les distributeurs étrangers. Les principes de construction du réseau ont un impact sur la capacité à intégrer les nouvelles installations de consommation ou de production à moindre cout, et à assurer les exigences sociétales,notamment pour ce qui concerne la continuité de fourniture. Cette thèse permet de comparer ces choix techniques majeurs avec les pratiques rencontrées à l'étranger, pour situer le réseau français et ses spécificités dans un environnement technique international.Après avoir arrêté une perspective de développement des usages et des productions en France sur la base notamment des textes législatifs, l'architecture du réseau de distribution français est décrite. Les différences fonctionnelles de choix de structure dans le monde sont alors analysés, en soulignant les conséquences dans le dimensionnement par rapport au cas français. Puis l'équilibre entre niveaux de tension est questionné, ainsi que les effet des caractéristiques du territoire sur le réseau. Enfin, des choix techniques nouveaux sont proposés après analyse des points forts et des points faibles des variantes existant dans le monde<br>Faced to a context of a global lack of growth in electricity consumption, but with many potential development of new uses, added with the appearance of more and more dispersed generation, the main French distribution grid utility needs to question and compare its choicesconcerning grid structure and exploitation practices. Grid building principles have a greatimpact over its capacity to integrate at low cost consumption and production facilities, whilemeeting society needs, mainly continuity of supply. This work allows to compare thosetechnical choices between France and other countries, to determine where French utilitystands and what are its specific features in a worldwide technical environment.After setting a perspective about uses and production development, mainly on the basis of French legislation, the overall distribution grid architecture is described. Functional differences in structure choices in the world are then analysed, their consequences in thesizing of equipments is underlined. Then the equilibrium between voltage levels is questioned,as the effect of territorial features on the grid. Finally, new technical choices are proposed after advantages and drawbacks analysis of existing world grids

Orientador: Fernando de Azevedo Silva<br>Banca: Edson Cocchieri Botelho<br>Banca: Antonio Carlos Ancelotti Filho<br>Resumo: Neste trabalho é apresentado um estudo analítico e numérico a respeito das tensões superficiais entre dois elementos. Quando uma força externa é aplicada a dois corpos em contato, verifica-se a existência de uma pequena deformação entre os elementos, causando um achatamento no plano de contato e criando uma zona de altas tensões de formato elíptico. Com a repetição cíclica destes carregamentos, pode ocorrer a perda progressiva de material superficial dos elementos envolvidos. De forma a investigar este fenômeno, esta dissertação realizou a análise detalhada de dois casos específicos encontrados na mecânica: o contato existente entra a esfera e a pista interna de um rolamento (contato esfera/plano), e o contato entre uma roda e um trilho ferroviário (contato cilindro/plano). Este estudo é essencial para a compreensão de como a aplicação de um carregamento externo pode influenciarna superfície de dois elementos. A análise foi realizada através de duas abordagens: uma analítica, através das equações oriundas da Teoria de Hertz, e outra numérica, através de programas computacionais de elementos finitos. Com os resultados verificados, foi feito uma série de gráficos que ilustram o comportamento das tensões ao longo dos eixos, além da análise da área afetada pela ação das tensões superficiais. Por fim, verificou-se a existência de tensões normais compressivas máximas encontradas no plano de contato entre os elementos, sendo a maior tensão localizada na direção do eixo de aplicação ... (Resumo completo, clicar acesso eletrônico abaixo)<br>Abstract: An analytical and numerical study regarding contact stresses between two elements is presented in this work. When an external force is applied to two bodies in contact, a small deformation between the elements appears, flattening the contact plane and creating high elliptical stresses. The cyclical repetition of these stresses can cause the progressive loss of surface material from the bodies. To verify this phenomenon, this work developed a detailed analysis of two specific cases found in many mechanical applications: the contact between a sphere and an inner ring of a bearing (sphere/plane contact) and the contact between a wheel and a rail track (cylinder/plane contact). This study is essential to the understanding of the influence in the surface of these two elements caused by an external load. The analysis was performed using two different approaches: one analytical, using Hertz equations, and one numerical, using computational simulations and finite element software. After the results were validated, a number of graphics were developed using the Hertz Equations for contact stresses to illustrate how the stresses behave along the axis, as well as the analysis of the area affected by the contact stresses. It was found that the maximum compressive stresses are located at the contact plane between the bodies, and the highest stress is found along the axis where the load was applied. When the depth is increased, all normal stresses tend to decrease until they became null. At... (Complete abstract click electronic access below)<br>Mestre

AbstractThis chapter examines the policy context and administrative systems associated with the resumption of assisted child migration from the United Kingdom to Australia in 1947. During the Second World War, the Australian Commonwealth Government came to see child migration as an increasingly important element in its wider plans for post-war population growth. Whilst initially developing a plan to receive up to 50,000 ‘war orphans’ shortly after the war in new government-run cottage homes, the Commonwealth Government subsequently abandoned this, partly for financial reasons. A more cost-effective strategy of working with voluntary societies, and their residential institutions, was adopted instead. Monitoring systems of these initial migration parties by the UK Government were weak. Whilst the Home Office began to formulate policies about appropriate standards of care for child migrants overseas, this work was hampered by tensions between the Home Office and the Commonwealth Relations Office about the extent to control over organisations in Australia was possible.

Riser recoil analysis for drilling at a harsh environment, deepwater site is particularly challenging. Recoil analysis results are used in conjunction with results of other riser analysis to develop a practical and safe riser management plan for drilling with a dynamically-positioned drillship at a site where rapidly-developing, high seastates occur frequently. Details of the recoil analysis are discussed along with brief references to other riser analyses that were carried out. The recoil analysis showed that criteria to avoid contact between the LMRP and BOP stack after disconnect and to limit slack in the riser tensioner ropes governed the selection of top tension settings. These recoil criteria also governed the maximum sea state in which the riser could remain connected. Recoil analysis was an important part of the effort to develop a practical and safe drilling riser management plan for a challenging location.

This paper studies the optimal plan for inspection and maintenance of steel structural components in tension by uniform corrosion, considering the following: A deteriorating model uncertain in time is considered, the probability to detect damage during the inspections is modeled, if damage is detected, the structural component is repaired, the failure probability of the component over time is considered supposing that the demands and capacities are random in time, the optimal plan will be the one in which the expected costs (costs of inspection, repair and failure) are minimum in the life cycle of the component, allowing to detect the number of inspections that minimize the expected costs; to determine the optimal plan, all the possibilities that are given of the tree diagram are studied, where each inspection has two existent possibilities: repair or not to repair, the occurrence possibility of each branch in the resulting tree diagram is calculated. In addition, the influence of the variables and parameters are calculated as: the net discount rate of money (r), uniform corrosion rate (ν), the mean load (μS), failure costs (Cf), repair cost (Crep) inspection cost (Cins) and quality of a nondestructive inspection (η0.5). The results indicate that the optimal number of inspections in the life-cycle of the component is sensible to each of the parameters involved, therefore every value of the variables that intervene in an optimization study must be fully justified.

The Tension Leg Semisubmersible (TLS) floater is the second generation of the Free-Hanging Solid Ballast Semisubmersible (FHSB Semi) design. The FHSB Semi is the state-of-the-art design that maintains the advantages of the conventional Semisubmersibles and provides the motions of Spars. The FHSB Semi design is a conventional semisubmersible with an added feature of a Free-Hanging Solid Ballast tank (SBT) located deep below the hull keel level and connected through four groups of chains (on its four corners) to the semisubmersible hull. During the pre-service conditions, the chains are used to retract the SBT and maintain it at a close proximity to the hull keel to facilitate the transportation and installation operations. Once the semisubmersible is moored in-place, the chain system is operated to lower the SBT to its desired elevation below the hull keel and maintain it permanently connected to the semisubmersible hull during the in-service condition. The SBT provides substantial in-water weight and added mass that significantly reduce the platform response and maintains the chains in tension. In this paper, detailed description of the Tension Leg Semisubmersible (TLS) design as the second generation of the FHSB Semi is presented. The paper also includes discussions on the proposed project execution plan for the TLS covering the fabrication, transportation and installation as well as the added risks and risk mitigations associated with the new semisubmersible design and execution. A case study is introduced where a TLS is used as a dry tree host for a field located at 6,000 ft of water in the central Gulf of Mexico (GoM) harsh environment.

As a typical floating platform, TLP (Tension leg platform) is widely used around the world of the water depth from 140m to 1400m due to its significant advantages over other deep-water production systems. This paper describes a conventional TLP type application for relatively shallow water depth of 410m, it was studied for a potential development plan in China south sea. Considering the safety and efficiency in the construction, installation and operation, a comprehensive sensitivity study of the simulation results against various analysis/environment parameters (including column form, wind coefficients, tendon pretension, etc.) was carried out and the role of each critical parameter was analyzed deeply. The numerical simulations were conducted for 1000-yr Hurricane condition with collinear wind, wave, and current directions. The results based on this study show that the change of the column pattern (from round column to square column) does not have much difference on the TLP hydrodynamic performance without other conditions changed; the variation of pre-tension has limited influence to the TLP hydrodynamic performance as this relatively shallow water.

This paper proposes a trajectory generation technique for three-dof planar cable-suspended parallel robots. Based on the kinematic and dynamic modelling of the robot, positive constant ratios between cable tensions and cable lengths are assumed. This assumption allows the transformation of the dynamic equations into linear differential equations with constant coefficients for the positioning part, while the orientation equation becomes a pendulum-like differential equation for which accurate solutions can be found in the literature. The integration of the differential equations is shown to yield families of translational trajectories and associated special frequencies. This result generalizes the special cases previously identified in the literature. Combining the results obtained with translational trajectories and rotational trajectories, more general combined motions are analysed. Examples are given in order to demonstrate the results. Because of the initial assumption on which the proposed method is based, the ratio between cable forces and cable lengths is constant and hence always positive, which ensures that all cables remain under tension. Therefore, the acceleration vector remains in the column space of the Jacobian matrix, which means that the mechanism can smoothly pass through kinematic singularities. The proposed trajectory planning approach can be used to plan dynamic trajectories that extend beyond the static workspace of the mechanism.

Abstract The Mississippi Canyon 280-A platform, also known as Lena Guyed Tower located in 1,000 ft water depth in the Gulf of Mexico (GoM), was successfully decommissioned and reefed in-place in 2020. To meet the regulatory requirements on offshore platform decommissioning, i.e. BSEE decommissioning requirements and the LDWF artificial reef program, an environmental study and an engineering study were performed to ensure that the platform decommissioning satisfies these critical requirements on environmental protection and operational safety. The environmental study revealed the abundance of marine lives residing on the tower and rare coral species only observed in deepwater region. This justified the environmental benefit of turning the tower into an on-site artificial reef and functioning as a vibrant marine life habitat at the end of its production service life. The engineering study on Lena decommissioning, as addressed in this paper, involved three (3) stages of engineering work: tower decommissioning concepts and feasibility study; selected concept definition; and detailed tower reef-in-place laydown (toppling) plan and design. High-level tower reef-in-place criteria were set up in the early engineering stage as guidelines to the detailed laydown design, including specific project requirements on minimal environmental impact and safe offshore field operations. This engineering study relied heavily on multiple expert brainstorm sessions on various decommissioning concepts and options, and advanced structural modeling and computer simulations for assessment and design. A large number of tower structural models were developed to verify the plan and check various factors and risk scenarios that may affect the tower performance in different stages of the decommissioning operation. Advanced analytical techniques were developed and applied, which feature the driving mechanisms of the problem such as soil-structure-interaction, guyline tension, structural member contact and sliding, large displacement simulation, structural collapse, and hydrodynamics. Stringent quality assurance and testing procedures were followed to ensure the credibility of developed analytical techniques and engineering technologies. The most challenging part that differentiates the decommissioning engineering from typical structural design is how to properly estimate the platform in-situ "as-is" condition and carry out the assessment as such to make a regulatory compliant, feasible, reliable, and efficient plan. Therefore, engineering judgment had to go beyond the scope covered by existing industry codes and standards, and rely on the most recent advances in industry research and technology. This engineering study resulted in a clearly defined tower decommissioning plan and procedure, backed up with contingency plans for various risk scenarios and potential deviations in field operation due to limitations and/or uncertainties. The decommissioning plan minimized the offshore field construction scope and risk, and kept the required tower laydown pull loads within the capacity range of typical GoM offshore tugboats. As a result, the Lena tower was successfully laid down on seafloor in an anticipated reefing position, with no major deviations from the plan. Lena Guyed Tower is the first deepwater compliant structure decommissioned. This decommissioning effort may provide the most valuable information and lessons learned to the industry for similar decommissioning and abandonment operations in the future.

Abstract Polyester based mooring systems offer unique challenges from design, analysis and installation perspective. Non-linear elongation behavior of the fiber is key to these challenges. A good understanding of the fiber elongation characteristics is critical to the design of a robust and efficient mooring system. Mooring systems are one of the primary contributors to the CAPEX of the Floating Production Units (FPU) and the drive to develop cost effective systems has led to improvements/changes to mooring systems. Off-vessel tensioning has been in use for several years, but the option has recently received more in-depth consideration. Off-vessel tensioning is becoming the standard for floating systems with the elimination of on-vessel tensioning systems. The elimination of on-vessel tensioning system brings upon new challenges in terms of mooring line installation and tensioning. A key driver for these systems is the polyester rope pre-load criteria primarily used to remove construction stretch and jump the creep curve that the system may experience. The challenges to each project are unique, however, understanding and assessing the key design impacts will be beneficial to the industry. This paper focuses on the design of a polyester based mooring system with focus on polyester fiber elongation characteristics and its impact on the design and installation. A polyester test program is established to understand the rope elongation behavior and impact of various pre-load levels. Installation assessment is also performed to understand the installation vessel requirements to achieve various pre-loads. Based on the studies, design updates are made to the mooring system and a novel two tension regime mooring system is proposed. Design impact of the two pre-tension system on various design criterions are evaluated and presented in this paper. The paper also makes recommendations on target pre-load and elongation to be considered in systems that do not plan to re-tension their system post installation. Authors appreciate that recommendations and observations reported may not be applicable for all types of floaters and mooring system.

New structural materials that are light and durable are anticipated to reduce the running and maintenance costs of structures exposed to harsh marine environments, such as offshore oil production facilities, thereby reducing their life-cycle cost. This study aims to investigate the applicability of new materials to marine structures, focusing on their durability. To this end, a 5-year exposure test has been conducted from 1999 on 3 types of specimens (for corrosion observation, tension testing, and joint strength testing) made of 21 selected materials (6 nonferrous metals, 8 steels, 4 composite materials, and 3 rope materials). The specimens are exposed at 3 sites: Okinotori-shima and Miyako-jima, corrosive environments with high temperature and humidity, and a thermo-hygrostatic room in a laboratory. In 2003, the fourth year of the ongoing exposure testing, the results of the observation and experiments of specimens recovered in 2002 after exposure for 3 years are subjected to analysis. The authors have already reported the detailed plan of the exposure test, initial performance of the specimens, and results of investigation on specimens exposed for 1 year. This paper reports on the results of appearance observation of specimens at Okinotori-shima and Miyako-jima carried out mostly in 2001, as well as the findings from observation and experiments on specimens exposed for 2 years at Miyako-jima. The state of corrosion at each site was grasped during the appearance observation. Observation and tension tests on jointed and unjointed specimens at Miyako-jima also revealed the state of corrosion of each material during the 2nd year of exposure.

This paper proposes a trajectory planning technique for planar three-degree-of-freedom cable-suspended parallel robots. Based on the kinematic and dynamic modelling of the architecture, force constraints that can guarantee that cables remain under tension are obtained. Periodic parametric trajectories that extend beyond the static workspace are designed. The trajectories involve combined translations and rotations. Substituting the trajectories into the force constraints, interval arithmetics is used to search for global conditions on the trajectory parameters which ensure that the trajectories are feasible. Special frequencies related to combined rotational and translational motions are exposed which can be used to better exploit cable-suspended robots. Moreover, it is observed that the special frequencies related to the translation are akin to the natural frequency of pendulum-like systems. The proposed trajectory planning approach can be used to plan combined rotational and translational dynamic trajectories that can extend beyond the static workspace of the mechanism, thereby opening novel applications and possibilities for cable-suspended robots.

The impact of mainsail sheet tension and traveler position on performance has been investigated, particularly under conditions when it is necessary to reduce power. Photographs of the mainsail on a Beneteau First 36.7 under various trim conditions were taken and analyzed to determine sail shape. The resulting shapes were used to create a CFD model, and the aerodynamics forces on the sail plan were determined. The results strongly suggest that for this boat it is more efficient to reduce power by keeping the main sheeted hard and lowering the traveler than by keeping the traveler up and easing the sheet, although a small amount of sheet easing is beneficial. The lift distributions for all sail trim combinations investigated are underloaded near the masthead relative to an elliptic distribution, which means that any additional twist in the main increases the induced drag. The difference in performance is almost entirely attributable to differences in the induced drag.

This study investigated the causes for premature, transverse cracking on urban jointed plain concrete pavements in Illinois. A field survey of 67 sections throughout Illinois coupled with ultrasonic evaluation was completed to synthesize the extent of premature cracking on urban JPCP. The visual survey showed some transverse and longitudinal cracks were a result of improper slab geometry (excessive slab length and width). Ultrasonic tests over the contraction joints determined some notched joints had not activated and adjacent transverse cracks were likely formed as a result. Three-dimensional finite-element analyses confirmed that cracking would not develop as a result of normal environmental factors and slab-base frictional restraint. The concrete mixture also did not appear to be a contributing factor to the premature cracks. Finally, the lack of lubrication on dowel bars was determined to potentially be a primary mechanism that could restrain the transverse contraction joints, produce excessive tensile stresses in the slab, and cause premature transverse cracks to develop.

1.1 Macroeconomic summary Economic recovery has consistently outperformed the technical staff’s expectations following a steep decline in activity in the second quarter of 2020. At the same time, total and core inflation rates have fallen and remain at low levels, suggesting that a significant element of the reactivation of Colombia’s economy has been related to recovery in potential GDP. This would support the technical staff’s diagnosis of weak aggregate demand and ample excess capacity. The most recently available data on 2020 growth suggests a contraction in economic activity of 6.8%, lower than estimates from January’s Monetary Policy Report (-7.2%). High-frequency indicators suggest that economic performance was significantly more dynamic than expected in January, despite mobility restrictions and quarantine measures. This has also come amid declines in total and core inflation, the latter of which was below January projections if controlling for certain relative price changes. This suggests that the unexpected strength of recent growth contains elements of demand, and that excess capacity, while significant, could be lower than previously estimated. Nevertheless, uncertainty over the measurement of excess capacity continues to be unusually high and marked both by variations in the way different economic sectors and spending components have been affected by the pandemic, and by uneven price behavior. The size of excess capacity, and in particular the evolution of the pandemic in forthcoming quarters, constitute substantial risks to the macroeconomic forecast presented in this report. Despite the unexpected strength of the recovery, the technical staff continues to project ample excess capacity that is expected to remain on the forecast horizon, alongside core inflation that will likely remain below the target. Domestic demand remains below 2019 levels amid unusually significant uncertainty over the size of excess capacity in the economy. High national unemployment (14.6% for February 2021) reflects a loose labor market, while observed total and core inflation continue to be below 2%. Inflationary pressures from the exchange rate are expected to continue to be low, with relatively little pass-through on inflation. This would be compatible with a negative output gap. Excess productive capacity and the expectation of core inflation below the 3% target on the forecast horizon provide a basis for an expansive monetary policy posture. The technical staff’s assessment of certain shocks and their expected effects on the economy, as well as the presence of several sources of uncertainty and related assumptions about their potential macroeconomic impacts, remain a feature of this report. The coronavirus pandemic, in particular, continues to affect the public health environment, and the reopening of Colombia’s economy remains incomplete. The technical staff’s assessment is that the COVID-19 shock has affected both aggregate demand and supply, but that the impact on demand has been deeper and more persistent. Given this persistence, the central forecast accounts for a gradual tightening of the output gap in the absence of new waves of contagion, and as vaccination campaigns progress. The central forecast continues to include an expected increase of total and core inflation rates in the second quarter of 2021, alongside the lapse of the temporary price relief measures put in place in 2020. Additional COVID-19 outbreaks (of uncertain duration and intensity) represent a significant risk factor that could affect these projections. Additionally, the forecast continues to include an upward trend in sovereign risk premiums, reflected by higher levels of public debt that in the wake of the pandemic are likely to persist on the forecast horizon, even in the context of a fiscal adjustment. At the same time, the projection accounts for the shortterm effects on private domestic demand from a fiscal adjustment along the lines of the one currently being proposed by the national government. This would be compatible with a gradual recovery of private domestic demand in 2022. The size and characteristics of the fiscal adjustment that is ultimately implemented, as well as the corresponding market response, represent another source of forecast uncertainty. Newly available information offers evidence of the potential for significant changes to the macroeconomic scenario, though without altering the general diagnosis described above. The most recent data on inflation, growth, fiscal policy, and international financial conditions suggests a more dynamic economy than previously expected. However, a third wave of the pandemic has delayed the re-opening of Colombia’s economy and brought with it a deceleration in economic activity. Detailed descriptions of these considerations and subsequent changes to the macroeconomic forecast are presented below. The expected annual decline in GDP (-0.3%) in the first quarter of 2021 appears to have been less pronounced than projected in January (-4.8%). Partial closures in January to address a second wave of COVID-19 appear to have had a less significant negative impact on the economy than previously estimated. This is reflected in figures related to mobility, energy demand, industry and retail sales, foreign trade, commercial transactions from selected banks, and the national statistics agency’s (DANE) economic tracking indicator (ISE). Output is now expected to have declined annually in the first quarter by 0.3%. Private consumption likely continued to recover, registering levels somewhat above those from the previous year, while public consumption likely increased significantly. While a recovery in investment in both housing and in other buildings and structures is expected, overall investment levels in this case likely continued to be low, and gross fixed capital formation is expected to continue to show significant annual declines. Imports likely recovered to again outpace exports, though both are expected to register significant annual declines. Economic activity that outpaced projections, an increase in oil prices and other export products, and an expected increase in public spending this year account for the upward revision to the 2021 growth forecast (from 4.6% with a range between 2% and 6% in January, to 6.0% with a range between 3% and 7% in April). As a result, the output gap is expected to be smaller and to tighten more rapidly than projected in the previous report, though it is still expected to remain in negative territory on the forecast horizon. Wide forecast intervals reflect the fact that the future evolution of the COVID-19 pandemic remains a significant source of uncertainty on these projections. The delay in the recovery of economic activity as a result of the resurgence of COVID-19 in the first quarter appears to have been less significant than projected in the January report. The central forecast scenario expects this improved performance to continue in 2021 alongside increased consumer and business confidence. Low real interest rates and an active credit supply would also support this dynamic, and the overall conditions would be expected to spur a recovery in consumption and investment. Increased growth in public spending and public works based on the national government’s spending plan (Plan Financiero del Gobierno) are other factors to consider. Additionally, an expected recovery in global demand and higher projected prices for oil and coffee would further contribute to improved external revenues and would favor investment, in particular in the oil sector. Given the above, the technical staff’s 2021 growth forecast has been revised upward from 4.6% in January (range from 2% to 6%) to 6.0% in April (range from 3% to 7%). These projections account for the potential for the third wave of COVID-19 to have a larger and more persistent effect on the economy than the previous wave, while also supposing that there will not be any additional significant waves of the pandemic and that mobility restrictions will be relaxed as a result. Economic growth in 2022 is expected to be 3%, with a range between 1% and 5%. This figure would be lower than projected in the January report (3.6% with a range between 2% and 6%), due to a higher base of comparison given the upward revision to expected GDP in 2021. This forecast also takes into account the likely effects on private demand of a fiscal adjustment of the size currently being proposed by the national government, and which would come into effect in 2022. Excess in productive capacity is now expected to be lower than estimated in January but continues to be significant and affected by high levels of uncertainty, as reflected in the wide forecast intervals. The possibility of new waves of the virus (of uncertain intensity and duration) represents a significant downward risk to projected GDP growth, and is signaled by the lower limits of the ranges provided in this report. Inflation (1.51%) and inflation excluding food and regulated items (0.94%) declined in March compared to December, continuing below the 3% target. The decline in inflation in this period was below projections, explained in large part by unanticipated increases in the costs of certain foods (3.92%) and regulated items (1.52%). An increase in international food and shipping prices, increased foreign demand for beef, and specific upward pressures on perishable food supplies appear to explain a lower-than-expected deceleration in the consumer price index (CPI) for foods. An unexpected increase in regulated items prices came amid unanticipated increases in international fuel prices, on some utilities rates, and for regulated education prices. The decline in annual inflation excluding food and regulated items between December and March was in line with projections from January, though this included downward pressure from a significant reduction in telecommunications rates due to the imminent entry of a new operator. When controlling for the effects of this relative price change, inflation excluding food and regulated items exceeds levels forecast in the previous report. Within this indicator of core inflation, the CPI for goods (1.05%) accelerated due to a reversion of the effects of the VAT-free day in November, which was largely accounted for in February, and possibly by the transmission of a recent depreciation of the peso on domestic prices for certain items (electric and household appliances). For their part, services prices decelerated and showed the lowest rate of annual growth (0.89%) among the large consumer baskets in the CPI. Within the services basket, the annual change in rental prices continued to decline, while those services that continue to experience the most significant restrictions on returning to normal operations (tourism, cinemas, nightlife, etc.) continued to register significant price declines. As previously mentioned, telephone rates also fell significantly due to increased competition in the market. Total inflation is expected to continue to be affected by ample excesses in productive capacity for the remainder of 2021 and 2022, though less so than projected in January. As a result, convergence to the inflation target is now expected to be somewhat faster than estimated in the previous report, assuming the absence of significant additional outbreaks of COVID-19. The technical staff’s year-end inflation projections for 2021 and 2022 have increased, suggesting figures around 3% due largely to variation in food and regulated items prices. The projection for inflation excluding food and regulated items also increased, but remains below 3%. Price relief measures on indirect taxes implemented in 2020 are expected to lapse in the second quarter of 2021, generating a one-off effect on prices and temporarily affecting inflation excluding food and regulated items. However, indexation to low levels of past inflation, weak demand, and ample excess productive capacity are expected to keep core inflation below the target, near 2.3% at the end of 2021 (previously 2.1%). The reversion in 2021 of the effects of some price relief measures on utility rates from 2020 should lead to an increase in the CPI for regulated items in the second half of this year. Annual price changes are now expected to be higher than estimated in the January report due to an increased expected path for fuel prices and unanticipated increases in regulated education prices. The projection for the CPI for foods has increased compared to the previous report, taking into account certain factors that were not anticipated in January (a less favorable agricultural cycle, increased pressure from international prices, and transport costs). Given the above, year-end annual inflation for 2021 and 2022 is now expected to be 3% and 2.8%, respectively, which would be above projections from January (2.3% and 2,7%). For its part, expected inflation based on analyst surveys suggests year-end inflation in 2021 and 2022 of 2.8% and 3.1%, respectively. There remains significant uncertainty surrounding the inflation forecasts included in this report due to several factors: 1) the evolution of the pandemic; 2) the difficulty in evaluating the size and persistence of excess productive capacity; 3) the timing and manner in which price relief measures will lapse; and 4) the future behavior of food prices. Projected 2021 growth in foreign demand (4.4% to 5.2%) and the supposed average oil price (USD 53 to USD 61 per Brent benchmark barrel) were both revised upward. An increase in long-term international interest rates has been reflected in a depreciation of the peso and could result in relatively tighter external financial conditions for emerging market economies, including Colombia. Average growth among Colombia’s trade partners was greater than expected in the fourth quarter of 2020. This, together with a sizable fiscal stimulus approved in the United States and the onset of a massive global vaccination campaign, largely explains the projected increase in foreign demand growth in 2021. The resilience of the goods market in the face of global crisis and an expected normalization in international trade are additional factors. These considerations and the expected continuation of a gradual reduction of mobility restrictions abroad suggest that Colombia’s trade partners could grow on average by 5.2% in 2021 and around 3.4% in 2022. The improved prospects for global economic growth have led to an increase in current and expected oil prices. Production interruptions due to a heavy winter, reduced inventories, and increased supply restrictions instituted by producing countries have also contributed to the increase. Meanwhile, market forecasts and recent Federal Reserve pronouncements suggest that the benchmark interest rate in the U.S. will remain stable for the next two years. Nevertheless, a significant increase in public spending in the country has fostered expectations for greater growth and inflation, as well as increased uncertainty over the moment in which a normalization of monetary policy might begin. This has been reflected in an increase in long-term interest rates. In this context, emerging market economies in the region, including Colombia, have registered increases in sovereign risk premiums and long-term domestic interest rates, and a depreciation of local currencies against the dollar. Recent outbreaks of COVID-19 in several of these economies; limits on vaccine supply and the slow pace of immunization campaigns in some countries; a significant increase in public debt; and tensions between the United States and China, among other factors, all add to a high level of uncertainty surrounding interest rate spreads, external financing conditions, and the future performance of risk premiums. The impact that this environment could have on the exchange rate and on domestic financing conditions represent risks to the macroeconomic and monetary policy forecasts. Domestic financial conditions continue to favor recovery in economic activity. The transmission of reductions to the policy interest rate on credit rates has been significant. The banking portfolio continues to recover amid circumstances that have affected both the supply and demand for loans, and in which some credit risks have materialized. Preferential and ordinary commercial interest rates have fallen to a similar degree as the benchmark interest rate. As is generally the case, this transmission has come at a slower pace for consumer credit rates, and has been further delayed in the case of mortgage rates. Commercial credit levels stabilized above pre-pandemic levels in March, following an increase resulting from significant liquidity requirements for businesses in the second quarter of 2020. The consumer credit portfolio continued to recover and has now surpassed February 2020 levels, though overall growth in the portfolio remains low. At the same time, portfolio projections and default indicators have increased, and credit establishment earnings have come down. Despite this, credit disbursements continue to recover and solvency indicators remain well above regulatory minimums. 1.2 Monetary policy decision In its meetings in March and April the BDBR left the benchmark interest rate unchanged at 1.75%.

To investigate the mechanical behavior and catenary action of restrained steel beam under fire, experiments were performed on five H-section restrained steel beams exposed to ISO-834 standard fire. At first, mechanical property tensile tests were performed on 3 room-temperature specimens and 8 high-temperature specimens, and variation laws of the material properties of steel materials with temperature rising were investigated by the high-temperature steady-state tests. Through the fire experiments, the temperature data, mid-span deflections and failure modes of all specimens were obtained. The experimental results show that: (1) a restrained steel beam is prone to in-plane buckling failure under fire; (2) the loading ratio n and axial restraint stiffness Kx have great influences on the catenary action of restrained steel beam under fire; (3) when the loading ratio n is constant, the greater the axial restraint stiffness Kx, the later the catenary action occurs; when the axial restraint stiffness Kx is constant, the greater the loading ratio n, the earlier the catenary action occurs.