65 research outputs found
Ballast for Lifting: A novel lifting method for topsides of offshore platforms
No full textAmazing Grace will be needed for the removal of offshore platforms that are out of Pioneering Spirit 's reach. The base case design of Amazing Grace is an enlarged version of Pioneering Spirit (Figure 1). Amazing Grace uses mainly Quick drop Ballast tanks, releasing a lot of water at once, for lifting. Pioneering Spirit uses mainly a pneumatic-hydraulic system for fast lifting. The idea is to lift bigger platforms with a less complex system. The behaviour of the base case design of Amazing Grace when lifting the upper part of an offshore platform (topside) from its supporting structure (jacket) is studied in this work and the feasibility of the new Quick drop Ballast system is tested. To perform a feasibility study on lifting topsides with Amazing Grace , a set of design requirements is generated. Before using these design requirements, a one tank model is required to simulate the emptying of a tank. The dimensions of an existing Pioneering Spirit Quick drop Ballast tank are used. The model is validated by comparing its output to existing physical test data of emptying the same tank. To lift by means of heave only, a bigger volume is used for the one tank model. Once the Quick drop Ballast concept shows to be feasible, the next step is to introduce waves. Waves are modelled using the linear superposition method. An estimation of the time series duration is done by computing the standard deviation of the heave amplitude. For a converged standard deviation, the time series' minimum length needs to be 1200 seconds. The maximum heave amplitude, derived from another statistical analysis, is applied to the connection plateau (when Amazing Grace connects and starts lifting the topside without creating clearance). The results show that Amazing Grace 's mass, added mass, damping and stiffness (the coefficients of the equation of motion) need to be included to give a more accurate estimation of the dynamics for connecting Amazing Grace to the topside and the possible rebounce to the jacket. Although this is a conceptual study, the dynamics are included to get a better understanding of Amazing Grace 's response. To include the previously mentioned coefficients of the equation of motion, the Cummins equation is implemented. The excitation forces are the sum of the wave- and the Quick drop Ballast force. The Quick drop Ballast force is derived from the one tank model. A convergence study shows which time step is needed for this model to work accurately considering its application. The implementation of the Cummins' equation is verified by showing agreement between time- and frequency domain. A sensitivity analysis is used to show the effect of changing the model's main variables. The peak period has the biggest influence on Amazing Grace 's heave motion. By varying the coefficients of Cummins' equation in the range of 35.5 - 38 meters draught, the computed vessel motions show that the variation of the draught only has little influence. The Quick drop Ballast system is feasible for both the pretension- and fast lift phase when applying the Quick drop Ballast force at the centre of gravity. The Quick drop Ballast force vector is partly relocated at the bow for applying trim during fast lift. A comparison shows that both the required volume and the number of valves reduce by one third compared to the heave only concept. The maximum allowable trim per length of Amazing Grace is 1.5 meter. This maximum is exceeded by 0.2 meters. The 0.2 meters needs to be included for a future topside lift system (TLS) design. It is recommended to apply trim during fast lift since this simplifies the complexity of the Quick drop Ballast system by reducing the required volume of water and the number of valves.Offshore and Dredging Engineering | Floating Offshore Structur
Human Ellipse of Indian Pedestrians
No full textAbstractThe most important parameter for designing a pedestrian facility is the area required by a pedestrian to stand comfortably or make a comfortable movement. This area is referred as Body Ellipse (Human Ellipse) and depends on Shoulder Width and Body Depth of a human being (and also on the kind of activity i.e. Standing or Walking). In current practices, design of pedestrian facilities’ are according to the body ellipse of pedestrians experimented in The United States Of America (US-HCM 2010). Regional variances are marked in these physical characteristics that are dependent on human body dimensions to a greater extent, ultimately playing an important role in pedestrian’s convenience (capacity and Level of service of a facility) and design environment. This paper is an attempt to study the measurements of Body Ellipses i.e. body depth and shoulder width by carrying out videography surveys on the pedestrians in India (specifically Delhi). The analysis also includes, classifying the body dimensions according to gender and walking with/without baggage (handbag/backpack), along with the measurement of the Step length of pedestrians’ while walking which shall give out the area required for walking. These body dimensions have been compared with the standard body dimension available worldwide. The study location was a walkway in a commercial area in Delhi (India) with a sample size of 747 consisting of 132 females and 615 males. The extracted body dimension varies from 26.07 to 52.14 centimeter for body depth and 42.35 to 67.76 centimeters for shoulder width
Carbon nanotube grafted silica fibres: Characterising the interface at the single fibre level
Get PDF26/09/12 meb. Author version, OK to pub
Electronic cigarette use and perceptions during COVID-19
Get PDFThis study was designed to examine how the COVID-19 pandemic changed e-cigarette user habits and risk perceptions. A nationally distributed 52-item questionnaire assessed nicotine e-cigarette use, perceptions, COVID-19 diagnosis, demographic data, and vaping habits among respondents aged 16–96 years (n = 565). Questions were developed in-house to assess vaping habits of users and risk perceptions of nicotine containing e-cigarette users and non-users both before and during the COVID-19 pandemic. Seventy-six percent of non-users believed that e-cigarette use would lead to worse COVID-19 symptoms, compared to 40% of e-cigarette users (P < 0.001). Twenty-eight percent of non-users also believed that e-cigarette users were more likely to be infected with SARS-CoV-2, versus 11% of e-cigarette users (P < 0.001). Fifty-eight percent of e-cigarette users described themselves as making no change in their e-cigarette usage, 10% decreased e-cigarette use, and 32% increased e-cigarette use during the pandemic. Twenty-five percent of users switched to vaping non-socially during the pandemic (P < 0.001). Sixty-seven percent of e-cigarette users replied that they would decrease or stop vaping if diagnosed with COVID and 31% said they would continue (P < 0.001). These findings reveal there are large differences in risk perception of e-cigarette use between users and non-users. Additionally, our findings characterize the habits of e-cigarette users during the COVID-19 pandemic, revealing users report steady to increased use, more caution in social settings, and would reduce usage if diagnosed with COVID-19
Carbon nanotube grafted carbon fibres: A study of wetting and fibre fragmentation
Get PDF26/09/12 meb. Author version, OK to pub.Carbon nanotubes (CNTs) were grafted on IM7 carbon fibres using a chemical vapour deposition method.The overall grafting process resulted in a threefold increase of the BET surface area compared to the original primary carbon fibres (0.57 m2/g). At the same time, there was a degradation of fibre tensile strength by around 15% (depending on gauge length), due to the dissolution of iron catalyst into the carbon;
the modulus was not significantly affected. The wetting behaviour between fibres and poly(methyl
methacrylate) (PMMA) was directly quantified using contact angle measurements for drop-on-fibre systems and indicated good wettability. Single fibre fragmentation tests were conducted on hierarchical fibre/PMMA model composites, demonstrating a significant (26%) improvement of the apparent interfacial shear strength (IFSS) over the baseline composites. The result is associated with improved stress transfer between the carbon fibres and surrounding matrix, through the grafted CNT layer. The improved IFSS was found to correlate directly with a reduced contact angle between fibre and matrix
Author Correction: Mapping local patterns of childhood overweight and wasting in low- and middle-income countries between 2000 and 2017 (Nature Medicine, (2020), 26, 5, (750-759), 10.1038/s41591-020-0807-6)
Get PDFAn amendment to this paper has been published and can be accessed via a link at the top of the paper. © 2020, The Author(s)
Author Correction: Mapping local patterns of childhood overweight and wasting in low- and middle-income countries between 2000 and 2017 (Nature Medicine, (2020), 26, 5, (750-759), 10.1038/s41591-020-0807-6)
Get PDFAn amendment to this paper has been published and can be accessed via a link at the top of the paper. © 2020, The Author(s)
Author Correction: Mapping local patterns of childhood overweight and wasting in low- and middle-income countries between 2000 and 2017 (Nature Medicine, (2020), 26, 5, (750-759), 10.1038/s41591-020-0807-6)
Get PDFAn amendment to this paper has been published and can be accessed via a link at the top of the paper. © 2020, The Author(s)
Gun violence incidence during the COVID-19 pandemic is higher than before the pandemic in the United States
Get PDFDuring the coronavirus disease 2019 (COVID-19) pandemic, gun violence (GV) in the United States (U.S.) was postulated to increase strain on already taxed healthcare resources, such as blood products, intensive care beds, personal protective equipment, and even hospital staff. This report aims to estimate the relative risk of GV in the U.S. during the pandemic compared to before the pandemic. Daily police reports corresponding to gun-related injuries and deaths in the 50 states and the District of Columbia from February 1st, 2019, to March 31st, 2021 were obtained from the GV Archive. Generalized linear mixed-effects models in the form of Poisson regression analysis were utilized to estimate the state-specific rates of GV. Nationally, GV rates were 30% higher between March 01, 2020, and March 31, 2021 (during the pandemic), compared to the same period in 2019 (before the pandemic) [intensity ratio (IR) = 1.30; 95% CI 1.29, 1.32; p <0.0001]. The risk of GV was significantly higher in 28 states and significantly lower in only one state. National and state-specific rates of GV were higher during the COVID-19 pandemic compared to the same timeframe 1 year prior. State-specific steps to mitigate violence, or at a minimum adequately prepare for its toll during the COVID-19 pandemic, should be taken. © 2021, The Author(s)
The visceral screen: Between the cinemas of John Cassavetes and David Cronenberg, a Barthesian perspective
Get PDFThe thesis discusses two directors who are never considered together in academic discourse. Cassavetes’ perceived focus on events led by the dynamics of performance and his looseness of technique opposes the calculated compositions of the Cronenberg film, with its aesthetic of horrific images and its gallery of emotionally detached protagonists. Yet it is between such opposing methods of cinematic expression that the ineffable qualities of film aesthetics can be discovered. Cassavetes’ cinema achieves this by revelling in a surplus of activity that exceeds narrative, while the indescribable characteristics of the Cronenberg oeuvre is achieved through a systematic emptying of the image’s meaning through a simultaneous commitment to paring back emotion and portraying of images that are controversial and inconceivable. Taken together, the thesis identifies these aspects of film as ‘the visceral,’ a facet of the moving image that most certainly exists, but is resolutely, and disturbingly resistant to interpretation.
Roland Barthes’ writings are integral to a theory of the visceral. His re-evaluation of Saussurean semiology as a method of analyzing and undoing ideologically-imposed meanings informs readings of sequences from Cassavetes and Cronenberg’s films. Following Barthes, the thesis suggests that the existence of the visceral is realized as a resistance to ideological interpretations of the image, and so cannot be described. Ultimately, the inability of semiology to fully grasp certain aspects of the filmed image is put forward as a rejoinder to theories of the fiction film as principally a narrative medium
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