bluuebunny/crossref_metadata_2025_split huggingface dataset:
FTMC Turbine: A Marine Turbine for the Gulf Stream Current Off the Coast of Florida
Authors: Moreu Jaime , Barrett Robert , García-Morato Ricardo , Dragan Radu Stefan , Aguado Eduardo , Cooke Glynn 
Published: April 2019

Abstract
This paper describes a marine turbine concept specifically designed to harness the energy from the Gulf Stream Current. This current achieves, at some points off the East coast of Florida, a speed that ranges between 2 and 4 knots in the first 100m of water depth, for 85% of the time. A device in this region shall be at least 40m deep to avoid navigation and wave interference. Since in these fast regions the seabed is 200 to 500m deep, moored solutions are the most feasible option.
Moored turbines require buoyancy to allow the device to be located at the optimal depth quite easily. In our design the buoyancy is given by a nozzle, which does not obstruct the flow but accelerates it. Consequently the blade size is reduced and protected from shock.
The mooring consists of a tension-tether arrangement that significantly reduces the vertical displacements, minimizing the pressure variation in the air tanks. This tension-tethered mooring also reduces the footprint and can be arranged to allow the turbine to passively turn into the current direction, increasing the capacity factor. The device is installed by controlling the nozzle ballast water and air pressure, and by attaching the mooring line to a concrete block on the seabed. If maintenance is needed the operation can be reversed, helping to reduce OPEX.
The combination of a TLP (tension leg platform)-like mooring and a robust floater arranged as a nozzle makes the concept feasible. A magnetically-geared Pseudo Direct Drive (PDD®) generator ensures a robust, direct-drive, high torque, low speed and highly efficient solution that can operate in the inherently rough immersed conditions.
The design has been validated in 2018 through prototype testing at INTA-CEHIPAR model basin in Spain. Thus, the concept as an offshore alternative energy converter has been confirmed. The small-scale demonstrator is designed for 600 Nm and 6 kW, with rotational speeds of up to 100 rpm. During the tests, the generated power has been measured at different generator and current speeds with the device fixed. The levels of generated power and efficiency agree with the CFD calculations. Furthermore, the stability of the marine turbine has also been confirmed. Several configurations of mooring lines and stabilizers have been tested to ensure that not only the unit is self-steerable, but that it also minimizes Vortex-Induced Motions.
Regarding the business case, competitive values of the levelized cost of energy (LCOE) can be achieved because of the high power density available in the selected coastal locations combined with high capacity factors. This overcomes the higher capital expenditure (CAPEX) per MW of each unit, because it is fully immersed, compared to offshore wind solutions.
The project has been co-financed by the Eurostars Program.
Progressive Subsea Field Construction Benefits Projects Net Present Value
Authors: D'Huart Pierre-Emmanuel , Cocault-Duverger Vincent 
Published: April 2019

Abstract
In the "lower for longer" barrel price environment, new projects and field developments need cost effective improved approaches; amongst them, the concept of "Progressive Subsea Field Construction". In this alternative concept, construction of elements that are not critical to first oil but only here to support the assets integrity - typically subsea pipelines foundations and consolidating structures - is deferred to the operational life of the facilities, thus benefiting the cash-flow and net present value of a project. This principle is well known to field architects that strive at ensuring that the cash generated from early production is used to finance the rest of the development - "Production while drilling" is a typical example of such approach.
In the vision conveyed in this paper, part of the structural construction can be delivered as a continuous (staged) service rather than an initial investment.
The paper analyzes two real cases of pipelines in deep-water West Africa, representing the evolution of the state of the art over the past 15 years. It then benchmarks these real cases against a novel approach, to demonstrate the benefits of continuous service in staged construction and integrity management.
Results provided in this paper demonstrate that there is benefit to the economics of a project, a minimal increase of 2% of a pipeline system Net Present Value, in setting a monitoring procedure, a monitoring device (like a resident subsea inspection vehicle) and data management system to allow for continuous construction. The paper also demonstrates that economic benefit is furthermore amplified when time comes to extend the life of the asset, in such case the Net Present Value of the same system increases by 5%.
Since the case study focuses on pipeline anchoring, the paper also attempts at showing this concept could be used more extensively in full field developments.
Indeed, the novel approach proposed in this paper opens the door to a completely novel collaboration model between contractors and operators, establishing continuity of construction during the full life cycle of a field. It aims at generating discussions and new ways of thinking to help the industry evolve towards lower costs of development and more sustainable contracting models.
Optimization of Drilling in Deep-Offshore Gulf of Mexico Using Geomechanics: Example from Buckskin
Authors: Ait-Ettajer Taoufik , Giannangeli Federico , Wood Jonathan , White John , Litun Adam 
Published: April 2019

Abstract
The optimization of the field development in the deepwater Gulf of Mexico (GOM) requires the collaboaration of multiple disciplines including drilling, geophysics, geology, petrophysics and geomechanics. The latter has been on the rise for several decades (Brehm, Davis, Ward, & Bowman, 2004) (Crawford, Homburg, Freysteinson, & Amoruso, 2018) (Zaki, Li, & Clinton, 2018), and it contributed to adding value through reducing the cost and the risks of drilling and completion in geologically complex areas such as the lower tertiary Wilcox. In the case of Buckskin field (Keathely Canyon), the use of 1D and 3D geomechanics techniques was necessary for the optimization of the drilling of the first development well in 2018, due to the high geological complexity (Ait-Ettajer, et al., 2017) and the chosen drilling design that included a highly deviated section through the reservoir section, in order to ensure a maximum reservoir contact and high well deliverability.
The geomechanics study, combined with a regional and local structural geology evaluation, indicated that the optimal well azimuth for the reservoir section is along the maximum horizontal stress since the tectonic regime is strike-slip (Tiwari, 2013), and that the completion integrity will be maintained throughout the life of the well. The results of the geomechanics study were in line with the prediction and ensured the injection of more than 4 million pounds of proppant in the reservoir section.
Triaxial Test System for Gas Hydrate-Bearing Sediments with Stable Conditions
Authors: Kang Chul-Whan , Kim Ah-Ram , Cho Gye-Chun , Lee Joo Yong 
Published: April 2019

Abstract
Under the seabed, gas hydrates are buried as solid materials that consist of water and gas molecules. Dissociation of gas hydrates induce mechanical properties change because solid-phase gas hydrates transformed to gas and liquid phase. Due to dissociation of gas hydrates, the bearing sediments can be collapsed or subsided. The triaxial test is a method for evaluating the mechanical properties of soil. Confining stress is applied to the specimen for simulating in-situ condition of the soil and axial loading is applied to induce shear failure. The modulus value can be derived through the relationship between the applying load and the strain level. Also cohesion and friction angle can be obtained based on the peak strength value according to various conditions of the confining stress. In the case of gas hydrate-bearing sediments, the mechanical properties change by the cementation effect of the gas hydrates. Therefore, experimental research for mechanical properties of gas hydrate-bearing sediments are required to understand mechanical behaviors of the sediments. However, high pressure and low temperature conditions are necessary to maintain stable condition of gas hydrates during the experiments. The triaxial tests should be conducted under the gas hydrate stable environment. In this study, in order to simulate the gas hydrate-bearing sediments, we constructed a system that can perform triaxial tests under high pressure and low temperature environment. Then, triaxial tests were carried out using specimens of gas hydrate-bearing sediments. Mechanical properties that achieved from the triaxial tests can be used as input parameters for the numerical analysis, which simulate the gas hydrate dissociation process.
Submerged Prehistoric Archaeology: Confronting Issues of Scale and Context on the Gulf of Mexico Outer Continental Shelf
Authors: Evans Amanda M. , Keith Matthew E. 
Published: April 2019

Abstract
The northwestern Gulf of Mexico outer continental shelf includes approximately 38,660,700 acres of submerged land under federal permitting authority, which are in turn subject to NEPA and NHPA Section 106-compliant archaeological survey. Of those nearly 40 million acres, sea-level curve data correlating with periods of known human occupation in North America suggest that those portions of the outer continental shelf out to the 60 m depth contour could have been exposed as dry land and available for human occupation during the Late Pleistocene and early Holocene before sea-level reached current levels. After four decades of regulatory compliant survey and assessment, no definitive prehistoric archaeological sites have been identified on the outer continental shelf. Although this is a daunting statistic, it does not accurately reflect the state of submerged prehistoric research. It is necessary to assess the data as they pertain to establishing both the temporal and spatial context of submerged prehistoric archaeology.
An Enhanced Assembly for Management of Open Hole Deepwater Standalone Screen Injector Completions
Authors: Williams Mark , Okengwu Victor , Bourgneuf Patrick , Guan Modem , Roane Thomas , Chaloupka Vladimir 
Published: April 2019

Abstract
A major operator with two large projects in Africa has been using a unique subassembly design, called the dual-isolation assembly (DIA), positioned on the bottom or toe of an open hole stand-alone screen (SAS) completion. The main objective of the DIA is to enhance the circulation process for washdown capabilities and provide efficient management and removal of the filter cake for the subsequent improvement of injectivity rates by lowering formation skin values on the injector wells.
After providing high-rate washdown through the float shoe at the toe of the completion, the DIA provides a means of circulating a filter cake removal treatment for the open hole. Once the filter cake treatment has been circulated sufficiently, the service tools are retrieved from the completion to surface. For an injector well, the flow path into the formation would be through the sand-control screens and the float shoe from the inside. Since the float shoe incorporates spring-loaded valves that would normally open during injection and close when pumping stops, it is beneficial to lock the valves out of service to prevent long term spring fatigue that could cause the valves to remain open at some point during the life of the well, allowing flow back of formation material inside the screens. After treatment of the open hole, an additional function of the DIA is to close the barrier isolation valve to isolate the formation while the filter cake treatment is activating.
As a continuation of an earlier paper (Roane, et al. 2018), the DIA has met all expectations on all 19 wells where it has been implemented in Africa. Due to enhanced procedures, the mechanical skins have averaged 2.5 and injectivity indices have averaged above 140 (B/D/psi) on these wells. Installation times have continually improved during the project due to following best practices.
In addition to fulfilling the requirements of these standalone screen (SAS) completions, the DIA design addresses other potential challenges, such as the prevention of hydraulic locks and formation swabbing, which can be detrimental and problematic to open hole completions. Other characteristics of the DIA that benefit open hole management were realized during the course of the project, such as the capability of the DIA to wash through the interior of the isolation barrier valve prior to closing the valve. Once closed, the valve can be re-opened and re-closed as required.
An important aspect of the physical attributes of the DIA that benefits logistics and running speed of the completion is its compact design allowing it to be completely assembled in the shop and shipped to location, such that it is a single pickup and makeup on the rig floor. This benefit has been exhibited by continual improvement in completion installation times throughout the project.
Assessing the Pile Driving Risk Due to the Presence of Boulders
Authors: Stevens Robert F. , Westgate Zack , Kocijan Jerko 
Published: April 2019

Abstract
Boulders are known to be present within foundation zone depths at some Atlantic East Coast wind energy development areas, which can make it difficult to level a piled jacket or template and can lead to the progressive collapse of the pile toe, causing premature refusal during pile driving. Although detection and avoidance are preferred over mitigation, numerical analysis methods are available to assess the risk of pile refusal, which allows for informed decisions on whether avoidance is required and what types of mitigation to consider during construction. Detailed numerical evaluation (using one-dimensional wave equation analyses and two- and three-dimensional finite difference and finite element modeling) was performed to develop a better understanding of stresses in the pile during driving. The numerical modeling evaluated the effect of strength, thickness, inclination, shoe length, wall thickness, and lateral continuity on pile stresses. A three-dimensional model of the pile and driving shoe subjected to stress-time histories was used to evaluate the stresses at the pile toe and at the transition from the pile to the driving shoe. Example results are presented to illustrate failure mechanisms of hard layers that include boulders, and high-level guidance is provided on operational sequences and potential contingency measures.
An Ideation and Roadmapping Workshop on the Development of AUVs for Oil & Gas Subsea Applications
Authors: Ghorbel Fathi H. , Kapusta Sergio , Allen John 
Published: April 2019

Abstract
The Subsea Oil and Gas industry is quickly moving toward deeper waters, complex, challenging, and dynamic working environments, while requiring the highest level of safety. Tasks that have been historically undertaken by workers in shallow waters are now performed by Remotely Operated underwater Vehicles (ROV) at water depths that humans cannot survive. ROV's are being used for intervention (Work-class ROV's, WROV) and for surveillance on drilling and production systems and pipeline. ROVs inherently have several limitations including requirement of a large operating crew, a need of a dynamically positioned surface vessel, tether management, and high cost mobilization and demobilization. Autonomous Underwater Vehicles (AUV) are now emerging with new capabilities and technologies that could make them more efficient and more cost effective than ROVs. New paradigms in shape, autonomy, sensing and communication and physical capabilities are needed to make AUVs the tool of choice for deepwater industry. An ideation and roadmapping workshop on the Development of AUVs for Subsea Applications was held at Rice Uni-versity that (i) generated a consensus from Oil & Gas operators, service providers, technology developers and providers, academics and policy makers of the anticipated needs and wishes for AUV technology in10 years, (ii) identified gaps between current status and future needs, and (iii) developed a roadmap of specific technical needs, gaps and solutions, and identified how and when those gaps might be closed.
Tissue Inhibitor of Metalloproteinase-1 Promotes Polymorphonuclear Neutrophil (PMN) Pericellular Proteolysis by Anchoring Matrix Metalloproteinase-8 and -9 to PMN Surfaces
Authors: Wang Xiaoyun , Rojas-Quintero Joselyn , Wilder Julie , Tesfaigzi Yohannes , Zhang Duo , Owen Caroline A. 
Published: April 2019

Abstract
Matrix metalloproteinase (MMP)–8 and –9 released by degranulating polymorphonuclear cells (PMNs) promote pericellular proteolysis by binding to PMN surfaces in a catalytically active tissue inhibitor of metalloproteinases (TIMP)-resistant forms. The PMN receptor(s) to which MMP-8 and MMP-9 bind(s) is not known. Competitive binding experiments showed that Mmp-8 and Mmp-9 share binding sites on murine PMN surfaces. A novel form of TIMP-1 (an inhibitor of soluble MMPs) is rapidly expressed on PMN surfaces when human PMNs are activated. Membrane-bound TIMP-1 is the PMN receptor for pro– and active MMP-8 and -9 as shown by the following: 1) TIMP-1 is strikingly colocalized with MMP-8 and -9 on activated human PMN surfaces and in PMN extracellular traps; 2) minimal immunoreactive and active Mmp-8 or Mmp-9 are detected on the surface of activated Timp-1−/− murine PMNs; and 3) binding of exogenous Timp-1 (but not Timp-2) to Timp-1−/− murine PMNs reconstitutes the binding of exogenous pro–Mmp-8 and pro–Mmp-9 to the surface of Timp-1−/− PMNs. Unlike full-length pro–Mmp-8 and pro–Mmp-9, mutant pro-Mmp proteins lacking the COOH-terminal hemopexin domain fail to bind to Mmp-8−/−x Mmp-9−/− murine PMNs. Soluble hemopexin inhibits the binding of pro–Mmp-8 and pro–Mmp-9 to Mmp-8−/−x Mmp-9−/− murine PMNs. Thus, the COOH-terminal hemopexin domains of pro–Mmp-8 and pro–Mmp-9 are required for their binding to membrane-bound Timp-1 on murine PMNs. Exposing nonhuman primates to cigarette smoke upregulates colocalized expression of TIMP-1 with MMP-8 and MMP-9 on peripheral blood PMN surfaces. By anchoring MMP-8 and MMP-9 to PMN surfaces, membrane-bound TIMP-1 plays a counterintuitive role in promoting PMN pericellular proteolysis occurring in chronic obstructive pulmonary disease and other diseases.
Community-based rehabilitation workers’ perspectives of wheelchair provision in Uganda: A qualitative study
Authors: Seymour Nikola , Geiger Martha , Scheffler Elsje 
Published: April 2019

Background: The challenges of wheelchair provision and use in less resourced settings are the focus of global efforts to enhance wheelchair service delivery. The shortage of professional wheelchair service providers in these settings necessitates the collaboration of multiple stakeholders, including community-based rehabilitation (CBR) workers, whose role needs to be further understood.Objectives: The aim of this study was to determine what CBR workers in three areas of Uganda perceived as (1) the challenges with wheelchair provision and use, (2) the factors contributing to these challenges, (3) the role they themselves can potentially play and (4) what facilitators they need to achieve this.Method: This qualitative study in the transformative paradigm comprised focus group discussions to gather perceptions from 21 CBR workers in three areas of Uganda, each with an operational wheelchair service, participant observations and field notes. Thematic analysis of data was implemented.Results: Community-based rehabilitation workers’ perceptions of challenges were similar while perceived causes of challenges differed as influenced by location, historical and current wheelchair availability and the CBR workers’ roles. Their main responsibilities included assistance in overcoming barriers to access the service, transfer of skills and knowledge related to wheelchairs, follow-up of users for wheelchair-related problem-solving, and user and community empowerment.Conclusion: Community-based rehabilitation workers can contribute in various ways to wheelchair service delivery and inclusion of wheelchair users; however, their capabilities are not consistently applied. Considering the diversity of contextual challenges, CBR workers’ range of responsive approaches, knowledge of networks and ability to work in the community make their input valuable. However, to optimise their contribution, specific planning for their training and financial needs and effective engagement in the wheelchair services delivery system are essential.
Evaluation of terrestrial pan-Arctic carbon cycling using a data-assimilation system
Authors: López-Blanco Efrén , Exbrayat Jean-François , Lund Magnus , Christensen Torben R. , Tamstorf Mikkel P. , Slevin Darren , Hugelius Gustaf , Bloom Anthony A. , Williams Mathew 
Published: April 2019

Abstract. There is a significant knowledge gap in the current state
of the terrestrial carbon (C) budget. Recent studies have highlighted a poor
understanding particularly of C pool transit times and of whether productivity
or biomass dominate these biases. The Arctic, accounting for approximately
50 % of the global soil organic C stocks, has an important role in the
global C cycle. Here, we use the CARbon DAta MOdel (CARDAMOM) data-assimilation system to
produce pan-Arctic terrestrial C cycle analyses for 2000–2015. This approach
avoids using traditional plant functional type or steady-state assumptions.
We integrate a range of data (soil organic C, leaf area index, biomass, and
climate) to determine the most likely state of the high-latitude C cycle at
a 1∘ × 1∘ resolution and also to provide general
guidance about the controlling biases in transit times. On average, CARDAMOM
estimates regional mean rates of photosynthesis of 565 g C m−2 yr−1
(90 % confidence interval between the 5th and 95th percentiles: 428, 741),
autotrophic respiration of 270 g C m−2 yr−1 (182, 397) and
heterotrophic respiration of 219 g C m−2 yr−1 (31, 1458),
suggesting a pan-Arctic sink of −67 (−287, 1160) g Cm−2 yr−1, weaker in tundra and stronger in taiga. However, our
confidence intervals remain large (and so the region could be a source of C),
reflecting uncertainty assigned to the regional data products. We show a
clear spatial and temporal agreement between CARDAMOM analyses and different
sources of assimilated and independent data at both pan-Arctic and local
scales but also identify consistent biases between CARDAMOM and validation
data. The assimilation process requires clearer error quantification for leaf area index (LAI) and biomass products to resolve these biases. Mapping of vegetation C stocks
and change over time and soil C ages linked to soil C stocks is required
for better analytical constraint. Comparing CARDAMOM analyses to global
vegetation models (GVMs) for the same period, we conclude that transit times
of vegetation C are inconsistently simulated in GVMs due to a combination of
uncertainties from productivity and biomass calculations. Our findings
highlight that GVMs need to focus on constraining both current vegetation C
stocks and net primary production to improve a process-based understanding of
C cycle dynamics in the Arctic.