The Stability of Fluid Production From a Flexible Riser

2002 ◽  
Vol 124 (2) ◽  
pp. 83-89 ◽  
Author(s):  
Jonathan A. Montgomery ◽  
Hoi C. Yeung
Keyword(s):  
Direct Consequence ◽  
Flow Assurance ◽  
Direct Impact ◽  
Flexible Riser ◽  
Unstable Flow ◽  
Flow Management ◽  
Fluid Production ◽  
Large Production ◽  
The Stability ◽  
Transition Type

The prediction of slug formation and slug size has a direct impact on the design of topsides separation facilities and flow assurance to the process. The characteristics and stability of liquid production from an S-shaped riser have been studied over a range of pressures, focusing on the implications for flow management. Severe slugging in an S-shaped riser gives a period of no liquid production, followed by a period of steady production and finally a large production spike, many times larger than the steady production. In contrast with classical severe slugging in a vertical or catenary riser, the transient spike is broken into two parts as a direct consequence of the bend in the line. Little attention has been paid to transition-type flows (between stable and unstable flow) previously. Data collected to date has shown transition flows have production peaks that are larger than those of classical severe slugging.

scholarly journals Poly Traditional Chinese Medicine formulation prepared with skin moisturizing properties

2020 ◽  
Author(s):  
Hong Meng ◽  
Jia-Rui Li ◽  
Yin-Mao Dong ◽  
Li Li ◽  
Yi-Fan He ◽  
...  
Keyword(s):  
Chinese Medicine ◽  
Traditional Chinese Medicine ◽  
Aloe Vera ◽  
Skin Barrier ◽  
Echinacea Purpurea ◽  
Raw Material ◽  
Extraction Temperature ◽  
Lycium Barbarum ◽  
Fluid Production ◽  
The Stability

Abstract Background Many traditional Chinese medicine compositions can moisturize the skin and utilize in cosmetics. Using a combination of Chinese Medicine Materials and guided by Traditional Chinese Medicine principles, this study selected Echinacea purpurea to protect the skin barrier, Dendrobium nobile to clear heat and promote fluid production, Sophora flavescens to clear heat for diminished inflammation, and Aloe vera combined Lycium barbarum to nourish yin, to together form a "poly TCM moisturizing formulation". Methods These poly plant extracts were investigated and optimized for the stability, safety and moisturizing ability. The combination moisturizing effect was determined by measuring the expression of FLG mRNA, CLDN-1 mRNA and AQP3 protein. Toxicological analysis included a red blood cell hemolysis test and a 3T3 phototoxicity test . Results It has been observed that by using polysaccharide yield as the evaluation criterion showed optimal extraction at a material-to-liquid ratio of 1:100, an extraction temperature of 100 °C, and an extraction time of 3 h. Moisturizing effect experiments showed that the expression of FLG mRNA, CLDN-1 mRNA and AQP3 protein was significantly increased. Toxicological tests showed that the composition was safe and caused no irritating effects. Conclusion Based on these results, this poly TCM moisturizing formulation is safe within moisturizing effects and can be used as a moisturizing raw material in cosmetics.

scholarly journals Upper and lower limits on the stability of calving glaciers from the yield strength envelope of ice

2011 ◽  
Vol 468 (2140) ◽  
pp. 913-931 ◽  
Author(s):  
J. N. Bassis ◽  
C. C. Walker
Keyword(s):  
Yield Strength ◽  
Water Depth ◽  
Shear Failure ◽  
Ice Sheets ◽  
Direct Consequence ◽  
Ice Thickness ◽  
Tightly Coupled ◽  
The Stability ◽  
Induced Changes ◽  
Lower Limits

Observations indicate that substantial changes in the dynamics of marine-terminating ice sheets and glaciers are tightly coupled to calving-induced changes in the terminus position. However, the calving process itself remains poorly understood and is not well parametrized in current numerical ice sheet models. In this study, we address this uncertainty by deriving plausible upper and lower limits for the maximum stable ice thickness at the calving face of marine-terminating glaciers, using two complementary models. The first model assumes that a combination of tensile and shear failure can render the ice cliff near the terminus unstable and/or enable pre-existing crevasses to intersect. A direct consequence of this model is that thick glaciers must terminate in deep water to stabilize the calving front, yielding a predicted maximum ice cliff height that increases with increasing water depth, consistent with observations culled from glaciers in West Greenland, Antarctica, Svalbard and Alaska. The second model considers an analogous lower limit derived by assuming that the ice is already fractured and fractures are lubricated by pore pressure. In this model, a floating ice tongue can only form when the ice entering the terminus region is relatively intact with few pre-existing, deeply penetrating crevasses.

Research Trends of the Labour Market in 2016

2016 ◽  
Vol 5 (4) ◽  
pp. 71-77
Author(s):  
Захаров ◽  
Dmitriy Zakharov
Keyword(s):  
Labor Market ◽  
Staff Development ◽  
Professional Growth ◽  
Human Resources Management ◽  
Direct Consequence ◽  
Market Participants ◽  
Top Managers ◽  
Market Situation ◽  
The Stability ◽  
The One

This article discusses the current trends, analysis and forecasts of the labor market situation in Russia. Results the effect of the global economic crisis on the labor market. It was revealed that the crisis has forced workers significantly revise their professional requirements. In particular, today the Russian top managers and key specialists emphasize employment is the stability of the company in the market, even the prospects for career and professional growth overshadowed. The recommendations on the adjustment of human resources management strategy of the organization, taking into account trends and forecasts of the labor market. The new targets have to work with the company personnel are performance evaluation and staff development. These strategic priorities, on the one hand — a direct consequence of the difficulties in the economy, dictating the most balanced market participants to expend resources, on the other hand — an attempt to control service personnel to reach a new level of business.

scholarly journals Stiffness in vortex—like structures due to chirality-domains within a coupled helical rare-earth superlattice

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Amitesh Paul
Keyword(s):  
Rare Earth ◽  
Domain Walls ◽  
Topological Defects ◽  
Magnetic Ordering ◽  
Direct Consequence ◽  
Magnetic Vortex ◽  
Range Magnetic Order ◽  
Wide Range ◽  
Out Of Plane ◽  
The Stability

Abstract Vortex domain walls poses chirality or ‘handedness’ which can be exploited to act as memory units by changing their polarity with electric field or driving/manupulating the vortex itself by electric currents in multiferroics. Recently, domain walls formed by one dimensional array of vortex—like structures have been theoretically predicted to exist in disordered rare-earth helical magnets with topological defects. Here, in this report, we have used a combination of two rare-earth metals, e.g."Equation missing" superlattice that leads to long range magnetic order despite their competing anisotropies along the out-of-plane (Er) and in-plane (Tb) directions. Probing the vertically correlated magnetic structures by off-specular polarized neutron scattering we confirm the existence of such magnetic vortex—like domains associated with magnetic helical ordering within the Er layers. The vortex—like structures are predicted to have opposite chirality, side—by—side and are fairly unaffected by the introduction of magnetic ordering between the interfacial Tb layers and also with the increase in magnetic field which is a direct consequence of screening of the vorticity in the system due to a helical background. Overall, the stability of these vortices over a wide range of temperatures, fields and interfacial coupling, opens up the opportunity for fundamental chiral spintronics in unconventional systems.

scholarly journals Dynamic Characteristics and Stability of Flexible Riser Under Consideration of Non-Uniform Tension and Internal Flow

2020 ◽  
Author(s):  
Dingbang Yan ◽  
Shuangxi Guo ◽  
Yilun Li ◽  
Jixiang Song ◽  
Min Li ◽  
...  
Keyword(s):  
Dynamic Characteristics ◽  
Oil And Gas ◽  
Internal Flow ◽  
Oil And Gas Industry ◽  
Travelling Wave ◽  
Flexible Riser ◽  
Modal Shape ◽  
Gas Industry ◽  
Uniform Tension ◽  
The Stability

Abstract As oil and gas industry is developing towards deeper ocean area, the length and flexibility of ocean risers become larger, which may induce larger-amplitude displacement of flexible riser response due to lower structural stiffness against environmental and operational loads. Moreover, suffering not only the external fluid loads coming from environmental ocean wave and current, these risers also convey internal flow. In other words, the dynamic characteristics and response of the flow-conveying riser face great challenge, such as bucking, divergence and flutter, because of the fluid-solid coupling of the internal hydrodynamics and riser structural dynamics. In this study the dynamic characteristics and stability of a flexible riser, under consideration of its internal flow and, particularly, non-uniform axial tension, are examined through our FEM numerical simulations. First, the governing equations and FEM models of a flexible riser with axially-varying tension and internal flow are developed. Then the dynamic characteristics, including the coupled frequency and modal shape, are presented, as considering the speed of internal speed changes. At last, the dynamic response and corresponding stability behaviors are discussed and compared with the cases of riser with uniform tension. Our FEM results show that the stability and response are quite different from riser with uniform tension. And, the time-spatial evolution of riser displacement exhibit a strong wave propagation phenomenon where travelling wave are observed.

Study of the Tip Leakage Flow in a Compressor Cascade With Incidence Exceeding the Stability Limit

2019 ◽  
Author(s):  
Markus W. Leitner ◽  
Stephan Staudacher ◽  
Martin G. Rose
Keyword(s):  
Water Table ◽  
Vortex Breakdown ◽  
Stability Limit ◽  
Leakage Flow ◽  
Angle Of Incidence ◽  
Compressor Cascade ◽  
Tip Leakage Flow ◽  
Unstable Flow ◽  
Tip Leakage ◽  
The Stability

Abstract In axial compressors, tip leakage flow is disadvantageous to efficiency and mass flow stability. We analyzed the tip leakage flow in a compressor cascade on a water table at various angles of incidence. When the angle of incidence is systematically increased, the flow rate is decreased and, finally, the stability limit is exceeded. To study the flow structures and vortex behavior, we installed Particle Tracking Velocimetry (PTV) on the water table. 3D-trajectories of the stable and unstable flow reveal significant effects. Increasing incidence generates a significant change in the nature of the flow. The tip leakage flow fluctuates and features unstable flow phenomena. A large blockage of the flow passage occurs, probably due vortex breakdown. Such a serious disturbance of the incoming flow may induce stall.

Building Trust in Politics

2016 ◽  
pp. 127-157
Author(s):  
Michele Lobina ◽  
Marco Bottone
Keyword(s):  
Latin America ◽  
Latin American ◽  
Public Support ◽  
Large Data ◽  
Direct Impact ◽  
Data Set ◽  
Political Behaviour ◽  
The Public ◽  
Trust In Institutions ◽  
The Stability

This chapter studies the process of trust building in politics by using large data set on political behaviour in Latin America. The results yielded by developed models indicate specific elements as the most influential on the popular trust in institutions. These observed determinants were enclosed in five macro classes: cohesion of society; economic factors; electoral transparency; efficiency of judicial organs; and crime diffusion. The analysis of the public support in governments and parliaments revealed that certain variables have a direct impact on the stability of the Latin American democracies, while other factors merely determine the likelihood of a government's reappointment.

Ideal magnetohydrodynamic stability in stellarators with subsonic equilibrium flow

2021 ◽  
Author(s):  
Carolin Nuehrenberg
Keyword(s):  
Mathematical Formulation ◽  
Radial Electric Field ◽  
Weak Form ◽  
Unstable Flow ◽  
Magnetic Surfaces ◽  
Ideal Mhd ◽  
Mhd Stability ◽  
Ideal Magnetohydrodynamic ◽  
The Stability ◽  
The Ideal

Abstract The effect of a subsonic flow, inherent to most stellarators because of a radial electric field, on their ideal magnetohydrodynamic (MHD) stability properties is studied employing the quasi-Lagrangian picture developed by Frieman and Rotenberg [1960 Rev. Mod. Phys. 32, 898]. The Mach number of the perpendicular ExB flow in stellarators is of order 0.01 and, therefore, admits the usage of a subsonic approximation in form of a static equilibrium. A mathematical formulation of the weak form of the stability equation with flow has been implemented in the ideal-MHD stability code CAS3D. This formulation uses magnetic coordinates and does not involve any derivatives across magnetic surfaces. In addition to the expected Doppler shift of frequencies, properties of the spectrum of the ideal MHD force operator, which are already known for tokamaks, but now also shown in the stellarator case, are: firstly, the appearance of unstable flow-induced continua stemming from the coupling of sound and Alfven continuum branches with equal mode numbers; and, secondly, the existence of flow-induced, global, stable modes near extrema of sound continuum branches, the extrema, in turn, being generated by the influence of a sheared flow on the static sound continua.

Influence of Pretreatment on the Free CaO in Steel Slag

2017 ◽  
Vol 904 ◽  
pp. 162-166
Author(s):  
Long Hua Wei ◽  
Xian Jin Qi ◽  
Xing Zhu ◽  
Hua Wang ◽  
Bin Hu ◽  
...  
Keyword(s):  
Steel Slag ◽  
Raw Material ◽  
Research Progress ◽  
Experimental Program ◽  
X Ray Diffraction ◽  
Cooking Temperature ◽  
Large Production ◽  
The Stability ◽  
Free Cao ◽  
Physical And Chemical

An experimental program was carried out to investigate how to improve the characteristics of steel slag. Mainly the pretreatment methods of cooking and autoclave were used to detect such as free CaO content in the steel slag. The physical and chemical characteristics of steel slag were measured by X-ray diffraction (XRD) and fluorescence (XRF) analysis. The aim of improving the slag utilization is an important way to resolve large production problem, and then the research progress of steel slag utilization at home and abroad are recycled as raw material to be applied. By means of those ways to manage steel slag we have received the following conclusions: With the increase of cooking temperature the content of free CaO is gradually reduced. When temperature higher than 90oC the means could greatly reduce the free CaO content from about 7% wt. to less than 2.5% wt. in 3 h. By means of autoclave pressure upto 1.5MPa could greatly reduce the free CaO content from about 7% wt. to less than 3.2% wt. in 3 h. Through the study of the relevant of steel slag after pretreatment can effectively reduce the free CaO content in the steel slag, improving the stability of the steel slag is advantageous to the seven used in the construction field.

Sign in / Sign up

Export Citation Format

Share Document