Transient Hydrodynamic Forces on a Disconnectable Turret Buoy

2014 ◽  
Author(s):  
Z. J. Huang ◽  
K. M. Walker ◽  
S. Lee ◽  
W. Thanyamanta ◽  
D. Spencer
Keyword(s):  
Hydrodynamic Forces ◽  
Analytical Models ◽  
Hydrodynamic Analysis ◽  
Simplified Approach ◽  
Large Size ◽  
High Production Rate ◽  
Calm Water ◽  
Computational Fluid Dynamics Cfd ◽  
High Production ◽  
True Time

For disconnectable turret-moored FPSOs, accurate prediction of turret buoy and FPSO motions during the buoy disconnection process is essential for safe operations. For deepwater high production rate systems, large size buoys are required to accommodate the large number of risers and heavy mooring legs. Analytical models of hydrodynamic forces on large size buoys must be verified before they are applied to motion predictions. To gain a better understanding of the transient hydrodynamic loads on the buoy and hydrodynamic interactions between the buoy and the hull during disconnection, we conducted a specially designed model test in a tow tank. In the model tests, both the buoy and the FPSO models were forced to oscillate by two independent actuators in calm water and in waves. Summary of test results, computed transient hydrodynamic forces from a simplified approach, a true time-domain transient hydrodynamic analysis based on instantaneous buoy positions, and computational fluid dynamics (CFD) results are presented in this paper.

Investigation on Optimization Strategies for the Hydrodynamic Design of DTMB 5415

2012 ◽  
Vol 479-481 ◽  
pp. 1950-1954 ◽  
Author(s):  
Jing Feng Huang ◽  
Bai Wei Feng
Keyword(s):  
Geometric Modeling ◽  
Water Resistance ◽  
Parametric Modeling ◽  
Hydrodynamic Performance ◽  
Shape Variation ◽  
Hydrodynamic Analysis ◽  
Form Generation ◽  
Calm Water ◽  
Computational Fluid Dynamics Cfd ◽  
Analysis Design

The paper contributes to the field of ship design by investigating the applicability of formal strategies to the optimization of a ship’s hydrodynamic performance. A study on the geometric modeling, hydrodynamic analysis, design evaluation and shape variation of a DTMB5415 is presented. Optimization Algorithm is utilized to explore the design space and to improve the hull shape. The hydrodynamic design process is implemented: An advanced parametric modeling kernel is applied for efficient form generation and variation. The hydrodynamic performance is analyzed by state-of-the-art Computational Fluid Dynamics (CFD) codes for calm water resistance. A commercial optimization system is used to integrate the various CAD and CFD tools and to carry out the optimization.

scholarly journals Characterization and optimization of extracellular enzymes production by Aspergillus niger strains isolated from date by-products

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Reda Bellaouchi ◽  
Houssam Abouloifa ◽  
Yahya Rokni ◽  
Amina Hasnaoui ◽  
Nabil Ghabbour ◽  
...  
Keyword(s):  
Aspergillus Niger ◽  
Culture Medium ◽  
Extracellular Enzymes ◽  
Enzyme Expression ◽  
Specific Enzyme ◽  
Enzymatic Production ◽  
High Production Rate ◽  
High Production ◽  
Incubation Temperatures ◽  
By Products

Abstract Background This work aims to study the optimal conditions of the fermentation culture medium used for the production of extracellular enzymes (amylase, cellulase, lipase, and protease) from previously isolated Aspergillus niger strains in date by-products. Results The five most powerful isolates selected based on the zone of degradation formed on Petri plates by the substrate were subjected to the quantitative evaluation of their enzymatic production. All five strains showed almost similar API-ZYM profiles, with minor variations observed at the level of some specific enzyme expression. The production of cellulase and amylase was depending on pH and incubation temperatures. ASP2 strain demonstrated the high production rate of amylase (at pH 5 and 30 °C) and cellulase (at pH 6 and 30 °C) for 96 h of incubation. Conclusion The A. niger showed the ability to produce several extracellular enzymes and can be used in the valorization of different agroindustrial residues.

scholarly journals Isotope separation of 176Lu a precursor to 177Lu medical isotope using broadband lasers

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
M. V. Suryanarayana
Keyword(s):  
Production Rate ◽  
Isotope Separation ◽  
Medical Applications ◽  
Optimum Conditions ◽  
High Production Rate ◽  
Laser Isotope Separation ◽  
High Production ◽  
System Requirements ◽  
Medical Isotope ◽  
Rhodamine Dye

AbstractA new photoionization scheme accessible by Rhodamine dye lasers is proposed for the isotope separation of 176Lu.$$5d6s^{2}\,{^{2}D_{{3/2}}} (0.0\, {\text{cm}}^{{ - 1}} )\mathop{\longrightarrow}\limits^{{573.8130\, {\text{nm}}}}5d6s6p\,{^{4}F_{{3/2}}^{o}} \left( {17427.28\, {\text{cm}}^{{ - 1}} } \right)\mathop{\longrightarrow}\limits^{{560.3114\, {\text{nm}}}}$$ 5 d 6 s 2 2 D 3 / 2 ( 0.0 cm - 1 ) ⟶ 573.8130 nm 5 d 6 s 6 p 4 F 3 / 2 o 17427.28 cm - 1 ⟶ 560.3114 nm $$6s{6p}^{2}\,{^{4}{P}_{5/2}}\left(35274.5 \,{\text{cm}}^{-1}\right){\to } Autoionization\, State {\to }{Lu}^{+}$$ 6 s 6 p 2 4 P 5 / 2 35274.5 cm - 1 → A u t o i o n i z a t i o n S t a t e → Lu + Optimum conditions for the laser isotope separation have been theoretically computed and compared with the previously reported work. The enrichment of ~ 63% can be obtained with > 22 mg/h production rate even when broadband lasers with bandwidth of 500 MHz are employed for the two step excitation. The simplified system requirements for the photoionization scheme combined with a high production rate of 176Lu than previously reported is expected to reduce the global shortage of 176Lu isotope for medical applications.

scholarly journals Can Frequency Account for the Grammatical Choices of Children and Adults in Nominal Modification Contexts? Evidence from Elicited Production and Child-Directed Speech

Languages ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. 35
Author(s):  
Emanuela Sanfelici ◽  
Petra Schulz
Keyword(s):  
Language Acquisition ◽  
Production Rate ◽  
Relative Clauses ◽  
Language Use ◽  
Spontaneous Speech ◽  
Production Task ◽  
Specific Context ◽  
High Production Rate ◽  
High Production ◽  
Acquisition Order

There is consensus that languages possess several grammatical variants satisfying the same conversational function. Nevertheless, it is a matter of debate which principles guide the adult speaker’s choice and the child’s acquisition order of these variants. Various proposals have suggested that frequency shapes adult language use and language acquisition. Taking the domain of nominal modification as its testing ground, this paper explores in two studies the role that frequency of structures plays for adults’ and children’s structural choices in German. In Study 1, 133 three- to six-year-old children and 21 adults were tested with an elicited production task prompting participants to identify an agent or a patient referent among a set of alternatives. Study 2 analyzed a corpus of child-directed speech to examine the frequency of passive relative clauses, which children, similar to adults, produced very often in Study 1. Importantly, passive relatives were found to be infrequent in the child input. These two results show that the high production rate of rare structures, such as passive relatives, is difficult to account for with frequency. We claim that the relation between frequency in natural speech and use of a given variant in a specific context is indirect: speakers may opt for the less grammatically complex computation rather than for the variant most frequently used in spontaneous speech.

Computational Fluid Dynamic Using Parallel Loop of Multi-Cores Processor

2014 ◽  
Vol 493 ◽  
pp. 80-85 ◽  
Author(s):  
C.L Siow ◽  
Jaswar ◽  
Efi Afrizal
Keyword(s):  
Fluid Flow ◽  
Early Stage ◽  
Fluid Dynamic ◽  
Visual Basic ◽  
Computer Hardware ◽  
Navier Stokes ◽  
Computer Memory ◽  
Large Size ◽  
Computational Fluid Dynamics Cfd ◽  
Reynolds Average

Computational Fluid Dynamics (CFD) software is often used to study fluid flow and structures motion in fluids. The CFD normally requires large size of arrays and computer memory and then caused long execution time. However, Innovation of computer hardware such as multi-cores processor provides an alternative solution to improve this programming performance. This paper discussed loop parallelize multi-cores processor for optimization of sequential looping CFD code. This loop parallelize CFD was achieved by applying multi-tasking or multi-threading code into the original CFD code which was developed by one of the authors. The CFD code was developed based on Reynolds Average Navier-Stokes (RANS) method. The new CFD code program was developed using Microsoft Visual Basic (VB) programming language. In the early stage, the whole CFD code was constructed in a sequential flow before it is modified to parallel flow by using VBs multi-threading library. In the comparison, fluid flow around the hull of round-shaped FPSO was selected to compare the performance of both the programming codes. Besides, executed results of this self-developed code such as pressure distribution around the hull were also presented in this paper.

Experimental Study of DRA for Vertical Two-Phase Annular Flow

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
R. L. J. Fernandes ◽  
B. A. Fleck ◽  
T. R. Heidrick ◽  
L. Torres ◽  
M. G. Rodriguez
Keyword(s):  
Pressure Gradient ◽  
Drag Reduction ◽  
Production Rate ◽  
Annular Flow ◽  
Liquid Holdup ◽  
Two Phase ◽  
High Production Rate ◽  
High Production ◽  
Feasibility Test ◽  
Main Effects

Experimental investigation of drag reduction in vertical two-phase annular flow is presented. The work is a feasibility test for applying drag reducing additives (DRAs) in high production-rate gas-condensate wells where friction in the production tubing limits the production rate. The DRAs are intended to reduce the overall pressure gradient and thereby increase the production rate. Since such wells typically operate in the annular-entrained flow regime, the gas and liquid velocities were chosen such that the experiments were in a vertical two-phase annular flow. The drag reducers had two main effects on the flow. As expected, they reduced the frictional component of the pressure gradient by up to 74%. However, they also resulted in a significant increase in the liquid holdup by up to 27%. This phenomenon is identified as “DRA-induced flooding.” Since the flow was vertical, the increase in the liquid holdup increased the hydrostatic component of the pressure gradient by up to 25%, offsetting some of reduction in the frictional component of the pressure gradient. The DRA-induced flooding was most pronounced at the lowest gas velocities. However, the results show that in the annular flow the net effect will generally be a reduction in the overall pressure gradient by up to 82%. The findings here help to establish an envelope of operations for the application of multiphase drag reduction in vertical flows and indicate the conditions where a significant net reduction of the pressure gradient may be expected.

scholarly journals Hydrodynamic Analysis for the Morphing Median Fins of Tuna during Yaw Motions

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Xiaohu Li
Keyword(s):  
Numerical Method ◽  
Hydrodynamic Forces ◽  
The Body ◽  
Robotic Fish ◽  
Hydrodynamic Performance ◽  
Hydrodynamic Analysis ◽  
Dorsal Fin ◽  
The Stability ◽  
Median Fins

Tuna can change the area and shape of the median fins, including the first dorsal, second dorsal, and anal fins. The morphing median fins have the ability of adjusting the hydrodynamic forces, thereby affecting the yaw mobility of tuna to a certain extent. In this paper, the hydrodynamic analysis of the median fins under different morphing states is carried out by the numerical method, so as to clarify the influence of the erected median fins on the yaw maneuvers. By comparing the two morphing states of erected and depressed, it can be concluded that the erected median fins can increase their own hydrodynamic forces during the yaw movement. However, the second dorsal and anal fins have limited influence on the yaw maneuverability, and they tend to maintain the stability of tuna. The first dorsal fin has more lift increment in the erection state, which can obviously affect the hydrodynamic performance of tuna. Moreover, as the median fins are erected, the hydrodynamic forces of the tuna’s body increase synchronously due to the interaction between the body and the median fins, which is also very beneficial to the yaw motion. This study indicates that tuna can use the morphing median fins to adjust its mobility and stability, which provides a new idea for the design of robotic fish.

scholarly journals Rapid Turnover and High Production Rate of Myeloid Cells in Adult Rhesus Macaques with Compensations during Aging

2018 ◽  
Vol 200 (12) ◽  
pp. 4059-4067 ◽  
Author(s):  
Ziyuan He ◽  
Carolina Allers ◽  
Chie Sugimoto ◽  
Nursarat Ahmed ◽  
Hideki Fujioka ◽  
...  
Keyword(s):  
Production Rate ◽  
Rhesus Macaques ◽  
Myeloid Cells ◽  
Rapid Turnover ◽  
High Production Rate ◽  
High Production

Booming Then, Sputtering Now

2021 ◽  
Vol 103 (3) ◽  
pp. 281-308
Author(s):  
Michael Woo
Keyword(s):  
World War Ii ◽  
Los Angeles ◽  
Low Income ◽  
Home Ownership ◽  
Homeless Population ◽  
World War ◽  
Housing Shortage ◽  
High Production Rate ◽  
Racial Barriers ◽  
High Production

This article reviews the post-World War II mass production of houses in Los Angeles and the roots of today’s housing shortage. Even with a high production rate, minorities and low-income Angelenos have experienced racial barriers and displacement. Today, L.A.’s homeless population is disproportionally Black, while home ownership is disproportionally white. The article concludes with four proposals for responding to today’s shortage of affordable and racially equitable housing.

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