The kurtosis statistic is introduced as a sensitive tool for efficient preliminary analysis of flowinduced vibration response data. The kurtosis of sequential blocks of time series data allows one to distinguish single mode lock-in events. The problem of predicting lock-in is then discussed. Instructional examples are introduced to illustrate the relative importance of flow-speed, power-in leng...

This paper presents results obtained as part of the DeepStar Phase 10 program on VIV Factors of Safety. The objective was to develop a general methodology to calibrate Factors of Safety for VIV-induced fatigue and to apply it to partially straked risers. This was achieved using reliability methods, accepted industry VIV prediction software and state-of-the-art model test experiments. Most oil c...

offshore pipelines used for oil and gas transportation are often buried to avoid damage from fishing activities and to provide thermal insulation. thermal expansion and contraction of the pipeline during operation can lead to lateral or upheaval buckling. a safe buried pipeline design must take into account a reliable evaluation of soil uplift resistance and pipe embedment depth. while the cost...

Abstract Gas-solid riser flow exhibits strong heterogeneous structure in both axial direction and radial directions. Recent experimental studies reveal that the general radial solids concentration profiles present a double ring structure and the formation of a solid core region which have a relative higher concentration than the annulus region. This paper is focused on a comprehensive modeling ...

The application of Gas-Liquid-solid circulating fluidized beds (GLSCBE) has increased recently in chemical, petrochemical and biochemical industries. Electrical Resistance Tomography (ERT) and optical fibre probe were applied to investigate local phase holdups distribution. Since ERT is applicable only to conductive phase(s), e.g. liquid phase in this study, optical fibre probe was employed sim...

Gas holdup and mixing time were characterized in a forced circulation internal loop draft-tube reactor (unaerated aspect ratio≈ 6, downcomero-riser cross-sectional area ratio = 0.493) as functions of the forced liquid superficial velocity in the riser (ULr) and the gas superficial velocity in he riser (UGr). Data were obtained in air–water system. The operation ranges were 0≤ULr ≤ 0.051 m/s and...

A gas-liquid-solid inverse  uidization airlift bioreactor was proposed by combining advantages of external-loop airlift reactors and inverse  uidized beds. This airlift bioreactor comprises a gas-liquid riser, a gas separator, a liquid-solid inverse  uidized downcomer and a bottom connector. The effects of the gas velocity and the particle loading on the gas holdup in the riser and the liqui...

This paper reports the results of an experimental study conducted to characterise the gas-liquid multiphase flows experienced within a vertical riser transporting a range of gas-liquid flow rates. The scale experiments were performed using an air/silicone oil mixture within a 6 m long riser. The superficial air velocities studied ranged from 0.047 to 2.836 m/ s, whilst maintaining a liquid supe...

In this paper, robust adaptive boundary control for a flexible marine riser with vessel dynamics is developed to suppress the riser’s vibration. To provide an accurate and concise representation of the riser’s dynamic behavior, the flexible marine riser with vessel dynamics is described by a distributed parameter system with a partial differential equation (PDE) and four ordinary differential e...

The effect of lingual surface inclination of the maxillary canine on the jaw muscle activity was investigated on five subjects. Several different metal maxillary canine risers were fabricated to change the lingual inclination. The EMG activity of the masseter and posterior temporal muscle was recorded bilaterally by means of bipolar surface electrodes simultaneously with the LED mandibular trac...