Academic literature on the topic 'Buoyancy program'
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Journal articles on the topic "Buoyancy program"
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Lesmana, Janice, and Jane Savitri. "Tipe Student Academic Support dan Academic Buoyancy pada Mahasiswa." Humanitas (Jurnal Psikologi) 3, no. 3 (December 22, 2019): 179–200. http://dx.doi.org/10.28932/humanitas.v3i3.2266.
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This study aims to overview the relationship between student academic support (informational, esteem, motivational and venting support) and academic buoyancy in students. 230 participants were selected used proportionate stratified random sampling technique. This study used a modified Student Academic Support Scale (SASS; Thompson & Mazer, 2009) and modified Academic buoyancy Scale (ABS; Martin & Marsh, 2008), correlated using Spearman’s correlation test. The results show that academic buoyancy has a significant positive relationship with esteem support (r = 0.168; p = 0.011), motivational support (r = 0.212; p = 0.001) and venting support (r = 0.158; p = 0.017), but doesn’t have relationship with informational support (r = 0.105; p = 0.111). Researcher suggests to do further research about contribution students' academic support to academic buoyancy. It is recommended to develop a mentoring program for students that facilitates mutual helping, care and motivating between students in the academic.
Keywords: Student Academic Support, Academic buoyancy
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Zhuang, Yizhou, Rong Fu, and Hongqing Wang. "How Do Environmental Conditions Influence Vertical Buoyancy Structure and Shallow-to-Deep Convection Transition across Different Climate Regimes?" Journal of the Atmospheric Sciences 75, no. 6 (May 23, 2018): 1909–32. http://dx.doi.org/10.1175/jas-d-17-0284.1.
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Abstract We developed an entraining parcel approach that partitions parcel buoyancy into contributions from different processes (e.g., adiabatic cooling, condensation, freezing, and entrainment). Applying this method to research-quality radiosonde profiles provided by the Atmospheric Radiation Measurement (ARM) program at six sites, we evaluated how atmospheric thermodynamic conditions and entrainment influence various physical processes that determine the vertical buoyancy structure across different climate regimes as represented by these sites. The differences of morning buoyancy profiles between the deep convection (DC)/transition cases and shallow convection (SC)/nontransition cases were used to assess preconditions important for shallow-to-deep convection transition. Our results show that for continental sites such as the U.S. Southern Great Plains (SGP) and west-central Africa, surface conditions alone are enough to account for the buoyancy difference between DC and SC cases, although entrainment further enhances the buoyancy difference at SGP. For oceanic sites in the tropical west Pacific, humidity dilution in the lower to middle free troposphere (~1–6 km) and temperature mixing in the middle to upper troposphere (>4 km) have the most important influences on the buoyancy difference between DC and SC cases. For the humid central Amazon region, entrainment in both the boundary layer and the lower free troposphere (~0–4 km) have significant contributions to the buoyancy difference; the upper-tropospheric influence seems unimportant. In addition, the integral of the condensation term, which represents the parcel’s ability to transform available water vapor into heat through condensation, provides a better discrimination between DC and SC cases than the integral of buoyancy or the convective available potential energy (CAPE).
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Suhesty, Aulia, and Zafira Noor Basuki. "Penyesuaian Diri dan Efikasi Diri Akademik terhadap Academic Buoyancy." Jurnal Basicedu 6, no. 3 (May 26, 2022): 5456–66. http://dx.doi.org/10.31004/basicedu.v6i3.2763.
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Penelitian ini bertujuan untuk mengetahui mengetahui pengaruh penyesuaian diri dan efikasi diri akademik terhadap academic buoyancy mahasiswa yang bekerja. Metode penelitian yang digunakan adalah kuantitatif. Subjek dalam penelitian ini adalah 107 mahasiswa Sekolah Tinggi X Kota Balikpapan yang bekerja kemudian dipilih dengan menggunakan teknik purposive sampling. Metode pengumpulan data yang digunakan ialah dengan skala academic buoyancy, penyesuaian diri dan efikasi diri akademik. Teknik analisis data yang digunakan ialah regresi linear berganda. Seluruh data yang telah terkumpul dianalisis menggunakan bantuan program Statistical Package for Social Science (SPSS) versi 26.0 for windows. Hasil penelitian menemukan bahwa: (1) terdapat pengaruh yang signifikan penyesuaian diri dan efikasi diri akademik terhadap academic buoyancy pada mahasiswa yang bekerja dengan nilai F hitung = 81.466 > F tabel = 3.08 dan nilai p = 0.000 serta memiliki konstribusi pengaruh (R2) sebesar 61%; (2) terdapat pengaruh yang signifikan penyesuaian diri terhadap academic buoyancy pada mahasiswa yang bekerja dengan nilai koefisien beta (β) = 0.385, t hitung = 4.142 > t tabel = 1.983 , dan nilai p = 0.000 (p < 0.05); (3) terdapat pengaruh yang signifikan efikasi diri akademik terhadap academic buoyancy pada mahasiswa yang bekerja dengan nilai koefisien beta (β) = 0.449, t hitung = 4.823 > t tabel = 1.983, dan nilai p = 0.000 (p < 0.05).
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Thompson, T. E., and J. F. Baker. "Heritability and Phenotypic Correlations of Six Pecan Nut Characteristics." Journal of the American Society for Horticultural Science 118, no. 3 (May 1993): 415–18. http://dx.doi.org/10.21273/jashs.118.3.415.
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Heritability estimates for pecan [Carya illinoinensis (Wangenh.) K. Koch] nut weight, nut buoyancy, nut volume, nut density, kernel weight, and percentage kernel were determined from 8748 nut samples representing 152 families collected during 25 years in the U.S. Dept. of Agriculture (USDA) pecan breeding program at Brownwood, Texas. Measurements were corrected for year-to-year environmental variability using least-squares constants of individual year effects. Adjusted values were then regressed on midparent means. Generally, heritability (h2) estimates were low to moderate: nut weight 0.35, nut buoyancy 0.18, nut volume 0.35, nut density 0.03, kernel weight 0.38, and percentage kernel 0.32. The low values are probably due to the extreme alternate bearing tendency of this species, since crop load affects pecan nut characteristics so directly. Phenotypic correlations among these traits showed that larger or heavier nuts had significantly higher kernel weight, buoyancy, and percentage kernel. Nut density increased with higher nut and kernel weight, but decreased with nut volume.
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Zeng, Xiping, Wei-Kuo Tao, Minghua Zhang, Christa Peters-Lidard, Stephen Lang, Joanne Simpson, Sujay Kumar, et al. "Evaluating Clouds in Long-Term Cloud-Resolving Model Simulations with Observational Data." Journal of the Atmospheric Sciences 64, no. 12 (December 1, 2007): 4153–77. http://dx.doi.org/10.1175/2007jas2170.1.
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Abstract Two 20-day, continental midlatitude cases are simulated with a three-dimensional (3D) cloud-resolving model (CRM) and are compared to Atmospheric Radiation Measurement Program (ARM) data. Surface fluxes from ARM ground stations and a land data assimilation system are used to drive the CRM. This modeling evaluation shows that the model simulates precipitation well but overpredicts clouds, especially in the upper troposphere. The evaluation also shows that the ARM surface fluxes can have noticeable errors in summertime. Theoretical analysis reveals that buoyancy damping is sensitive to spatial smoothers in two-dimensional (2D) CRMs, but not in 3D ones. With this theoretical analysis and the ARM cloud observations as background, 2D and 3D simulations are compared, showing that the 2D CRM has not only rapid fluctuations in surface precipitation but also spurious dehumidification (or a decrease in cloud amount). The present study suggests that the rapid precipitation fluctuation and spurious dehumidification be attributed to the sensitivity of buoyancy damping to dimensionality.
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Ciba, Ewelina, Paweł Dymarski, and Mirosław Grygorowicz. "Analysis of the Hydrodynamic Properties of the 3-Column Spar Platform for Offshore Wind Turbines." Polish Maritime Research 29, no. 2 (June 1, 2022): 35–42. http://dx.doi.org/10.2478/pomr-2022-0015.
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Abstract The article presents a design of a floating platform for offshore wind turbines. The concept is a modification of the Spar design and consists of three variable section columns connected to each other by a ballast tank in the lower part of the platform. This solution makes it possible to influence the position of the centre of buoyancy and the centre of mass of the structure. Compared to the classic Spar platform structure, the centre of buoyancy can be higher than mid-draft, which will provide the platform with greater stability. At the same time, this concept is better, in terms of technology, because of its modular structure and smaller bending radii.On the basis of the model testing performed, the hydrodynamic coefficients of the designed platform and its response to a given regular wave were determined (the transfer functions for heave and pitch motion were determined). Then, based on the damping coefficients, the platform was modelled in the ANSYS AQWA program and the results were very similar.
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Tagkalakis, Athanasios O. "Estimating the Elasticity of Corporate Income Tax to Output Gap in Greece." Public Finance Review 45, no. 2 (August 3, 2016): 205–31. http://dx.doi.org/10.1177/1091142115589971.
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Using quarterly data over the period 1999 to 2013, we estimate the elasticity of corporate income tax (CIT) revenue to output gap in Greece. The elasticity is estimated to be about 1.40 to 1.55 when we use the profit share in its construction, while it increases to 1.83 to 2.05 when profit is used in its construction. The high values of the new estimated elasticity imply substantial CIT buoyancy effects in the years to come, provided that the current reform program of the Greek economy remains on track.
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Ramey, Sandra L., Yelena Perkhounkova, Maria Hein, Nicole L. Bohr, and Amanda A. Anderson. "Testing a Resilience Training Program in Police Recruits: A Pilot Study." Biological Research For Nursing 19, no. 4 (March 30, 2017): 440–49. http://dx.doi.org/10.1177/1099800417699879.
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Background: Stress from multiple sources is inherent in law enforcement. However, it is possible to modify responses to stress with resilience training that includes teaching techniques to modify emotional and physical responses to stress, interface with mental health professionals, and practice sessions to improve self-regulation of responses to stress including coherence, a measure of heart rate variability. A gap exists in the research, however, regarding evaluation of the duration of effects after the initial resilience training. Method: Subjects included ( N = 34) recruits enrolled in summer 2015 at the Milwaukee Police Academy. An experimental design was used to compare recruits who received resilience training to recruits in the control group. Results: No statistically significant differences between the groups were found for self-reported measures of stress and resilience. For the treatment group ( n = 17), change in coherence was significant ( p < .001) and improvement in the Personal Organizational Quality Assessment Emotional Buoyancy subscale correlated significantly with the number of practice sessions ( r = .63, p = .01) and marginally with change in coherence ( r = .47, p = .07). Conclusion: Results confirm several significant effects of resilience training with recruits.
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Jiang, Zhong An, and Wang Yi. "Numerical Simulation of Dynamic Emergency Rescue and Regularities during Mine Fire Period." Advanced Materials Research 619 (December 2012): 336–41. http://dx.doi.org/10.4028/www.scientific.net/amr.619.336.
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Under the comprehensive consideration of “buoyancy effect” and “throttle effect” during mine fire period, the article used the geographic information system (GIS) technology, simulated the smoke pollution area, ventilation system junction temperature and state of airflow during mine fire period. Finishing a program for dynamic simulation of emergency rescue during mine fire period, which is significant for establishing fire pre-scheme and the decision-making during fire period. At the same time, the dynamic characteristic of ventilation system and selection of escaping route is also considered, which provides foundation for the rescuing the workers underground in time.
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Cooper, David, and Ingvil Gausemel. "OIL SPILL SORBENTS: TESTING PROTOCOL AND CERTIFICATION LISTING PROGRAM." International Oil Spill Conference Proceedings 1993, no. 1 (March 1, 1993): 549–51. http://dx.doi.org/10.7901/2169-3358-1993-1-549.
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ABSTRACT Environment Canada's Emergencies Engineering Division is spearheading a program in conjunction with the Canadian General Standards Board that would see the development of a certification and listing program in addition to a national standard for the testing of sorbent materials. Funding for this program is provided by Environment Canada (EC), Canadian Coast Guard (CCG), Marine Spill Response Corporation (MSRC), U.S. Coast Guard (USCG), and U.S. Minerals Management Service (MMS). The test methods are based upon those defined by the American Society for Testing and Materials and previous test methods developed by Environment Canada for our series of reports entitled Selection Criteria and Laboratory Evaluation of Oil Spill Sorbents. This series, which was started in 1975, encompasses a number of commercially available oil spill sorbents tested with different petroleum products and hydrocarbon solvents. The testing program will categorize the sorbents according to their operating characteristics. The main categories are oil spills on water, oil spills on land, and industrial use. The characteristics we will be evaluating with the new test protocols include initial and maximum sorption capacities, water pickup, buoyancy, reuse potential, retention profile, disintegration (material integrity), and ease of application and retrieval. In the near future we plan to incorporate changes to the test that would involve increasing our list of test liquids to encompass spills in an industrial setting, in addition to testing sorbent booms and addressing the disposal problem.
Dissertations / Theses on the topic "Buoyancy program"
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Jensen, Harold Franklin. "Variable buoyancy system metric." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/58193.
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Thesis (S.M.)--Joint Program in Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and the Woods Hole Oceanographic Institution), 2009.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 111-112).
Over the past 20 years, underwater vehicle technology has undergone drastic improvements, and vehicles are quickly gaining popularity as a tool for numerous oceanographic tasks. Systems used on the vehicle to alter buoyancy, or variable buoyancy (VB) systems, have seen only minor improvements during the same time period. Though current VB systems are extremely robust, their lack of performance has become a hinderance to the advancement of vehicle capabilities. This thesis first explores the current status of VB systems, then creates a model of each system to determine performance. Second, in order to quantitatively compare fundamentally different VB systems, two metrics, [beta]m and [beta]vol, are developed and applied to current systems. By determining the ratio of performance to size, these metrics give engineers a tool to aid VB system development. Finally, the fundamental challenges in developing more advanced VB systems are explored, and a couple of technologies are investigated for their potential use in new systems.
by Harold Franklin Jensen III.
S.M.
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Zhai, Ping Ph D. Massachusetts Institute of Technology. "Buoyancy-driven circulation in the Red Sea." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/95561.
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Thesis: Ph. D., Joint Program in Physical Oceanography (Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 175-180).
This thesis explores the buoyancy-driven circulation in the Red Sea, using a combination of observations, as well as numerical modeling and analytical method. The first part of the thesis investigates the formation mechanism and spreading of Red Sea Overflow Water (RSOW) in the Red Sea. The preconditions required for open-ocean convection, which is suggested to be the formation mechanism of RSOW, are examined. The RSOW is identified and tracked as a layer with minimum potential vorticity and maximum chlorofluorocarbon-12. The pathway of the RSOW is also explored using numerical simulation. If diffusivity is not considered, the production rate of the RSOW is estimated to be 0.63 Sv using Walin's method. By comparing this 0.63 Sv to the actual RSOW transport at the Strait of Bab el Mandeb, it is implied that the vertical diffusivity is about 3.4 x10-5 m 2 s-1. The second part of the thesis studies buoyancy-forced circulation in an idealized Red Sea. Buoyancy-loss driven circulation in marginal seas is usually dominated by cyclonic boundary currents on f-plane, as suggested by previous observations and numerical modeling. This thesis suggests that by including [beta]-effect and buoyancy loss that increases linearly with latitude, the resultant mean Red Sea circulation consists of an anticyclonic gyre in the south and a cyclonic gyre in the north. In mid-basin, the northward surface flow crosses from the western boundary to the eastern boundary. The observational support is also reviewed. The mechanism that controls the crossover of boundary currents is further explored using an ad hoc analytical model based on PV dynamics. This ad hoc analytical model successfully predicts the crossover latitude of boundary currents. It suggests that the competition between advection of planetary vorticity and buoyancy-loss related term determines the crossover latitude. The third part of the thesis investigates three mechanisms that might account for eddy generation in the Red Sea, by conducting a series of numerical experiments. The three mechanisms are: i) baroclinic instability; ii) meridional structure of surface buoyancy losses; iii) cross-basin wind fields.
by Ping Zhai.
Ph. D.
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Geiger, Sam R. (Sam Rayburn) 1971. "Hydrodynamic modeling of towed buoyant submarine antenna's [sic] in multidirectional seas." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/29045.
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Thesis (S.M.)--Joint Program in Oceanographic Engineering (Massachusetts Institute of Technology, Dept. of Ocean Engineering, and the and Woods Hole Oceanographic Institution), 2000.Includes bibliographical references (p. 100-101).
A finite difference computer model is developed to simulate the exposure statistics of a radio frequency buoyant antenna as it is towed in a three-dimensional random seaway. The model allows the user to prescribe antenna properties (length, diameter, density, etc.), sea conditions (significant wave height, development of sea), tow angle, and tow speed. The model then simulates the antenna-sea interaction for the desired duration to collect statistics relating to antenna performance. The model provides design engineers with a tool to predict antenna performance trends, and to conduct design tradeoff studies. The floating antenna envisioned is for use by a submarine operating at modest speed and depth.
by Sam R. Geiger.
S.M.
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Artnak, Edward Joseph. "Development and assessment of CFD models including a supplemental program code for analyzing buoyancy-driven flows through BWR fuel assemblies in SFP complete LOCA scenarios." Thesis, 2012. http://hdl.handle.net/2152/ETD-UT-2012-12-6836.
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This work seeks to illustrate the potential benefits afforded by implementing aspects of fluid dynamics, especially the latest computational fluid dynamics (CFD) modeling approach, through numerical experimentation and the traditional discipline of physical experimentation to improve the calibration of the severe reactor accident analysis code, MELCOR, in one of several spent fuel pool (SFP) complete loss-of-coolant accident (LOCA) scenarios. While the scope of experimental work performed by Sandia National Laboratories (SNL) extends well beyond that which is reasonably addressed by our allotted resources and computational time in accordance with initial project allocations to complete the report, these simulated case trials produced a significant array of supplementary high-fidelity solutions and hydraulic flow-field data in support of SNL research objectives.
Results contained herein show FLUENT CFD model representations of a 9x9 BWR fuel assembly in conditions corresponding to a complete loss-of-coolant accident scenario. In addition to the CFD model developments, a MATLAB based control-volume model was constructed to independently assess the 9x9 BWR fuel assembly under similar accident scenarios. The data produced from this work show that FLUENT CFD models are capable of resolving complex flow fields within a BWR fuel assembly in the realm of buoyancy-induced mass flow rates and that characteristic hydraulic parameters from such CFD simulations (or physical experiments) are reasonably employed in corresponding constitutive correlations for developing simplified numerical models of comparable solution accuracy.text
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Hoevekamp, Tobias B. "Buoyant flow simulation programs with interactive graphics." Thesis, 1995. http://hdl.handle.net/1957/35524.
Full textBooks on the topic "Buoyancy program"
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Hoevekamp, Tobias B. Buoyant flow simulation programs with interactive graphics. 1995.
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Rodi, Wolfgang. Turbulent Buoyant Jets and Plumes : HMT: The Science and Applications of Heat and Mass Transfer. Reports, Reviews and Computer Programs. Elsevier Science & Technology Books, 2014.
Find full textBook chapters on the topic "Buoyancy program"
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Cebeci, Tuncer, and P. Bradshaw. "Buoyant Flows." In Solutions Manual and Computer Programs for Physical and Computational Aspects of Convective Heat Transfer, 88–94. New York, NY: Springer New York, 1989. http://dx.doi.org/10.1007/978-1-4899-6710-7_9.
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Rivers, Toby, and Richard A. Volkert. "Slow cooling in the metamorphic cores of Grenvillian large metamorphic core complexes and the thermal signature of the Ottawan orogenic lid." In Laurentia: Turning Points in the Evolution of a Continent. Geological Society of America, 2022. http://dx.doi.org/10.1130/2022.1220(16).
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ABSTRACT Prolonged slow cooling (average 1–3 °C/m.y.) of Ottawan phase granulite-facies gneisses (peak temperature ≥850 °C ca. 1090–1080 Ma) through the argon closure temperatures (TC) of hornblende ca. 980–920 Ma and biotite ca. 890–820 Ma in the western Grenville Province and in an inlier in the central Appalachians is well established, but its tectonic setting has not been systematically investigated. Here, the case is made that this slow cooling occurred in the suprasolidus cores of large metamorphic core complexes that were exhumed during mid-Ottawan (ca. 1050 Ma) extensional orogenic collapse. The ductile midcrustal metamorphic cores of the large metamorphic core complexes are overlain across gently dipping extensional detachments by a brittle-ductile cover composed of upper orogenic crust, parts of which preserve evidence of relict pre-Ottawan fabrics and peak prograde Ottawan temperatures of <500 °C (TC of Ar in hornblende), collectively implying thermal, structural, and rheological decoupling across the detachments. Slow average rates of cooling of the orogenic midcrust for >150 m.y. imply an anomalously hot upper mantle and mask short periods of more rapid cooling indicated by analyses of retrograde diffusional mineral zoning patterns. It is suggested that these slow average rates of cooling, coupled with slow average rates of exhumation of ≤0.1 km/m.y. modeled for one data set, were a result of decompression melting of rising asthenosphere and emplacement of voluminous mafic intrusions within or at the base of the crust, which reduced the buoyancy of the residual thinned lithosphere. This process is compatible with either delamination of subcontinental lithospheric mantle or slab rollback. The high-strain extensional detachments of the large metamorphic core complexes are sites of amphibolite-facies retrogression, suggesting a feedback between ingress of hydrous fluid, which was likely derived from beneath the detachment during crystallization of migmatite, and strain. Extensional juxtaposition of the hot midcrust (T >850 °C) and cooler cover (T <500 °C) across the detachments led to conductive heating of the base of the cover, locally raising its temperature above 500 °C, as recorded by amphibolite-facies metamorphism and young cooling ages. The slow cooling and exhumation of Grenvillian large metamorphic core complexes contrast with much faster rates in smaller metamorphic core complexes in other settings (e.g., North American Cordillera). The slow rates of these processes in large metamorphic core complexes are attributed to the prolonged high temperature and low viscosity of their metamorphic cores due to proximity of the asthenosphere, and to the intrusion of voluminous asthenospheric mafic magmas that both advected heat and reduced lithospheric buoyancy.
Conference papers on the topic "Buoyancy program"
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Lehner, F. K., D. Marsal, L. Hermans, and A. Van Kuy. "A model of secondary oil migration as a buoyancy‐driven segregated flow." In SEG Technical Program Expanded Abstracts 1989. Society of Exploration Geophysicists, 1989. http://dx.doi.org/10.1190/1.1889890.
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Thompson, Hugh, Mehemosh B. Irani, and Lyle D. Finn. "Some Aspects of Spar Platform Buoyancy Can Loads." In ASME 2002 21st International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2002. http://dx.doi.org/10.1115/omae2002-28387.
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A finite element program is developed to analyze the dynamics of buoyancy cans within the centerwell of Spar platforms. The time domain non-linear finite element model includes the effects of the hydrodynamics of the water within the centerwell, and, the gap between the buoyancy cans and guides. The forces on the buoyancy can guide structure due to Spar motions is studied in the present paper. The theoretical results are validated with experimental and field measurements. 1:20.89 scale model tests are conducted to measure the buoyancy can motions and guide reaction forces for a range of gap sizes and specified Spar motions. A Spar platform is also instrumented to measure the guide forces in actual field conditions. The prototype field data is analyzed and compared with the numerical predictions.
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Simmonds, Gordon R., and Lance N. Thomas. "Incorporating Muskeg Soil Shear Strength Into Buoyancy Control Design." In 1998 2nd International Pipeline Conference. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/ipc1998-2093.
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For the past four years, NOVA Gas Transmission Ltd. (NGTL) has included the backfill shear strength in buoyancy control design for natural gas pipelines built and operated in muskeg soil laden terrain. Incorporation of muskeg soil shear strength has resulted in major cost reductions. In typical muskeg soil laden terrain, the weighting requirement for NPS 4 and smaller pipelines has been eliminated, while the need for weighting of larger pipelines has been significantly reduced. Traditionally, muskeg soil shear strength has not been considered due to an absence of adequate theoretical and performance data. NGTL has constructed a series of laboratory and field studies in an attempt to quantify the contribution of “muskeg soil shear strength.” The results of this research program, when combined with a rudimentary field investigation, are part of NGTL’s current buoyancy control design methodology for pipelines traversing muskeg soil laden terrain. This paper presents a practical methodology used by NGTL for buoyancy control. Design examples are provided to calculate two design components; the maximum tolerable muskeg depth and optimum weight spacing. The paper concludes with a discussion of construction and operational considerations which influence buoyancy control design.
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Wu, Jie, Halvor Lie, Yiannis Constantinides, and Rolf J. Baarholm. "NDP Riser VIV Model Test With Staggered Buoyancy Elements." In ASME 2016 35th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/omae2016-54503.
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The Norwegian Deepwater Program (NDP) has over several years working on conceptual development and design of new steel riser solutions for deep water and harsh environment. For the steel lazy wave riser (SLWR) design, the buoyancy section is a critical segment. When subjected to current, both the buoyancy elements and the riser may experience vortex induced vibrations (VIV), which can lead to fast accumulation of fatigue damage and amplified drag loads. As part of developing robust SLWR, it is crucial to understand the current induced loads and responses on various staggered buoyancy configurations. In order to investigate the interaction of bare pipe section and buoyancy elements and its effect on VIV, hydrodynamic model tests were carried out in MARINTEK’s ocean basin in 2014. The test pipe is 38 m in length and 3 cm in diameter. The length of each buoyancy element 0.15 m and its diameter is 0.15 m. The ratio between buoyancy element diameter and riser diameter is 5. VIV response may depend on the spacing ratio of the length of the buoyancy segments and the gaps between two adjacent buoyancy elements, aspect ratio of the buoyancy element, and coverage percentage of buoyancy elements. Hence these parameters were varied and 6 different staggered buoyancy configurations were tested in uniform flows. The use of strakes to suppress VIV was also evaluated. The primary objective is to determine a range for these parameters that leads to the smallest VIV curvature (and hence an optimal riser fatigue design). The shedding frequency of the bare riser section is significantly higher than the buoyancy element due to its smaller diameter. Therefore, the bare riser section will excite much higher modes. As observed from the present tests, the fatigue damage is dominated by the bare riser component for all of the test configurations. The CF displacement of cases with the highest buoyancy coverage (50%) is often dominated by the vortex shedding of the buoyancy element. The use of stakes can effectively suppress the vortex shedding and leads to lowest fatigue damage in the test. In addition, the non-dimensional frequency of the buoyancy element is low (about 0.087–0.122) due to its small aspect ratios (1/1 and 2/1) in present tests. The vortex shedding of the buoyancy element seems to be weakened when the spacing ratio is larger than 1/1, which is different than earlier tests using buoyancy element with larger aspect ratio (≥5/1). The impact on the SLWR design is evaluated based on both present and other relevant model tests results.
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Gaskill, Collin, Jie Wu, and Decao Yin. "Full-Scale Reynolds Number VIV Testing of Tri-Helically Grooved Drill Riser Buoyancy Module." In ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-78605.
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A newly developed Tri-Helically Grooved drilling riser buoyancy module design was tested in the towing tank of SINTEF Ocean in June 2017. This new design aims to reduce riser drag loading and suppress vortex-induced vibrations (VIV). Objectives of the test program were two-fold: to assess the hydrodynamic performance of the design allowing for validation of previous computational fluid dynamics (CFD) studies through empirical measurements, and, to develop a hydrodynamic force coefficient database to be used in numerical simulations to evaluate drilling riser deformation due to drag loading and fatigue lives when subjected to VIV. This paper provides the parameters of the testing program and a discussion of the results from the various testing configurations assessed. Tests were performed using large scale, rigid cylinder test models at Reynolds numbers in the super-critical flow regime, defined as starting at a Reynolds number of Re = 3.5 × 105 – 5.0 × 105 (depending on various literatures) and continuing until Re = 3 × 106. Towing tests, with fixed and freely oscillating test models, were completed with both a bare test cylinder and a test cylinder with the Tri-Helical Groove design. Additional forced motion tests were performed on the helically grooved model to calculate lift and added mass coefficients at various amplitudes and frequencies of oscillation for the generation of a hydrodynamic force coefficient database for VIV prediction software. Significant differences were observed in the hydrodynamic performance of the bare and helically grooved test models considering both in-line (IL) drag and cross-flow (CF) cylinder excitation and oscillation amplitude. For the helically grooved model, measured static drag shows a strong independence from Reynolds number and elimination of the drag crisis region with an average drag coefficient of 0.63. Effective elimination of VIV and subsequent drag amplification was observed at relatively higher reduced velocities, where the bare test model shows a significant dynamic response. A small level of expected response for the helically grooved model was seen across the lower range of reduced velocities. However, disruption of vortex correlation still occurs in this range and non-sinusoidal and highly amplitude-modulated responses were observed.
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Luk, C. H., F. Yiu, and T. Rakshit. "Pipe-in-Pipe Substructure Modeling in Deepwater Riser Design Analysis." In ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/omae2009-79217.
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Substructure modeling using pipe-in-pipe (PiP) elements in a finite element program allows representation of dynamic interaction between riser components. This modeling technique is especially useful when it comes to the design of a complex riser system in deepwater applications. In this paper, the ABAQUS finite element program was used to illustrate the substructure models and the results for dynamic analysis of a classic Spar top tension riser (TTR) system in the Gulf of Mexico subjected to a given Hurricane Rita sea state. Nonlinear contacts between the buoyancy can and compliant guides are represented by two different substructure models: compliant guide surface model with friction and frictionless compliant guide spring model. The effects of centerwell hydrodynamic forces were considered. ABAQUS dynamic results were compared between the PiP substructure model and a conventional structure model treating the buoyancy can and the riser inside as a composite beam. The PiP guide friction surface model with centerwell hydrodynamics theoretically is the most representative model for riser analysis. However, the PiP guide spring model is more computationally efficient. It generates comparable guide loads but produces lower riser fatigue damage than the PiP guide friction surface model. The composite beam model leads to guide loads comparable to the PiP model, but cannot be used to determine the spacer loads between the buoyancy can and riser. The composite model also could underestimate riser stresses and riser fatigue damage within the buoyancy can region. The riser guide loads and riser damages from the calculation models without centerwell hydrodynamics are generally higher than those by the same calculation models with such consideration. It was concluded the PiP guide spring model can be used for riser design in lieu of the PiP guide surface model. The additional fatigue damage contribution from axial tension variation due to guide surface friction could be accounted for by adding a damage factor to the total fatigue damage along the riser.
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Norrbin, Clay S., and Dara W. Childs. "Lateral Equilibrium Position Analysis Program With Applications to Electric Submersible Pumps." In ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-63459.
Full textAbstract:
The long length of sub-sea Electric Submersible Pumps (ESPs) requires a large amount of annular seals. Loading caused by gravity and housing curvature changes the Static Equilibrium Position (SEP) of the rotor in these seals. This analysis predicts the SEP due to gravity and/or well curvature loading. The analysis also interfaces displays the rotordynamics around the SEP. A static and rotordynamic analysis is presented for a previously studied ESP model. This study differs by first finding the SEP and then performing a rotordynamic analysis about the SEP. Predictions are shown in a horizontal and a vertical orientation. In these two configurations, viscosities and clearances are varied through 4 cases: 1X 1cP, 3X 1cP, 1X 30cP, and 3X 30cP. In a horizontal, straight-housing position, the model includes gravity and buoyancy on the shaft. At 1cP-1X and 1cP-3X, the horizontal statics show a moderate eccentricity ratio for the shaft with respect to the housing. With 30cP-1X, the predicted static eccentricity ratio is low at 0.08. With 30cP-3X, the predicted eccentricity ratio increases to 0.33. Predictions for a vertical case of the same model are also presented. The curvature of the housing is varied in the Y-Z plane until rub or close-to-wall rub is expected. The curvature needed for a rub with a 1X 1cP fluid is 7.5 degrees of curvature. Curvature has little impact on stability. With both 1X 30cP and 3X 30cP, the maximum curvature for a static rub are over 25 degrees of curvature. Both 1X 30cP and 3X 30cP remain unstable with increasing curvature.
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Karatas¸, Hasan, Nijat Mastanzade, and Gu¨ven Kiymaz. "Model Experiments of a Tension Leg Platform." In ASME 2003 22nd International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2003. http://dx.doi.org/10.1115/omae2003-37020.
Full textAbstract:
The present paper presents the results of an experimental program on tension leg platforms. The geometric form of the test model structure is a conical shell surface. The model structure was tested in a hydraulics laboratory. The dynamic behavior depends on the buoyancy of the main structure and tension in the legs. Dynamic characteristic values for the TLP model test were compared against the theoretical values according to the Frude law. The difference between the model test values and theoretical values was found to be 7.5% and therefore is considered to be satisfactory.
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Cheng, Yongming, Chenteh Alan Yu, Guangqiang Yang, and Manuel R. Carballo. "Life Extension of Deepwater Risers Used for a Spar Application in Gulf of Mexico." In ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/omae2019-95804.
Full textAbstract:
Abstract Deepwater development in Gulf of Mexico (GoM) started about two decades ago. It is the time to evaluate the global integrity of the offshore production unit and riser system and explore the possibility of life extension. This paper investigates life extension of deepwater risers used for a spar application in GoM. A spar in GoM has been put into service for the past 17 years since it was installed in 2000. It was expected to extend the riser design life of 20 years by 10 more years. This paper first introduces the configuration of Steel Catenary Risers (SCRs) and Top Tensioned Risers (TTRs) used for the Spar platform. It then discusses the philosophy for life extension of deepwater risers by assessing the integrity of the riser system. Latest technology and monitored data are used for the assessment. The TTRs and SCRs are modelled using latest analysis programs that were not readily available when the risers were designed. The interaction between the TTR and buoyancy can tensioning system is modelled as a pipe-in-pipe system that considers the function of centralizers with a gap size. The contact interaction between buoyancy can / stem and supporting guides of the hull platform is modelled as non-linear spring elements. The spring elements connect normally to the hull centerline and allow vertical sliding movement of the buoyancy can tension / stem system with friction. The base line inspections of the vessel, SCRs, and TTRs was carried out in the same inspection campaign with the spar hull structure. As-built information, production and operational data was also used for a continuous service assessment. Environmental condition data to the state of the art, including measured spar VIM data, was used in the assessment of VIM fatigue damage to the risers. The investigation was based on the up-to-date analytical tools including latest FEA program ABAQUS and VIV prediction Shear7. It further computes the riser global performance including dynamic strength and fatigue damage with the contributions from wave fatigue, VIV and VIM. This paper finally draws a conclusion for the life extension of the risers for the application in GoM.
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Kim, Kyung Sung, Moo Hyun Kim, and Jong-Chun Park. "Simulation of Multi-Liquid-Layer Sloshing With Vessel Motion by Using Moving Particle Simulation." In ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-23565.
Full textAbstract:
For oil/gas production/processing platforms, multiple liquid layers can exist and their respective sloshing motions can also affect platform performance. To numerically simulate those problems, a new multi-liquid MPS (Moving Particle Simulation) method is developed. In particular, to better simulate the relevant physics, robust self-buoyancy model, interface searching model, and surface-tension model are developed. The developed multi-liquid MPS method is validated by comparisons against Molin et al’s (2012) three-liquid-sloshing experiment and the corresponding linear potential theory. The verified multi-liquid MPS program is subsequently coupled with a vessel-motion program in time domain to investigate their dynamic-coupling effects. In case of multiple liquid layers, there exist more than one sloshing natural frequencies, so the relevant physics can be much more complicated compared with the single-liquid-tank case. The numerical simulations also show that liquid cargo can function as a beneficial anti-rolling device.