bluuebunny/crossref_metadata_2025 huggingface dataset:
Prediction of Stress Correction Factor for Welded Joints Using Response Surface Models
Authors: Keprate Arvind , Donthi Nikhil
Published: October 2021

While performing fatigue reliability analysis of the butt-welded joints it is vital to estimate the Stress Concentration Factor (SCF) at these joints. A common approach adopted by industry to estimate the SCF at weld toes is to perform Finite Element Analysis (FEA) of the welded joints for different pipe sizes, flanges, valves etc. The SCF are calculated for each size by separately when required and are very time consuming. Although FEA is known for its accurate SCF calculation, but due to its high computational expense and time-consumption, SCF evaluation for different parameters makes the aforementioned method quite laborious. As an alternative response surface models (RSM) may be used for accurate estimation of SCF. The two basic steps in constructing a RSM are training and testing. The first corresponds to fitting a model to the intelligently chosen training points, while the second step involves comparing the predictions of the RSM to the actual response. This paper examines the applicability of 12 different RSMs for estimating SCF. The training and testing data is generated using FEA in ANSYS. In order to compare the accuracy of the RSMs, three metrics, namely, Root Mean Square Error (RMSE), Maximum Absolute Error (AAE), and Explained Variance Score (EVS) are used. A case study illustrating the applicability of the proposed approach is also presented.
A Method for Identifying Compatible Locations for Wave Energy Exploration With Different WECs
Authors: Ramos Sara , Gonçalves Marta , Guedes Soares Carlos
Published: October 2021

This paper aims to assess the marine space availability for the nearshore and offshore wave energy exploration while avoiding conflict with any technical, environmental, legal or other use restriction. Within the available areas retrieved in a GIS environment, it is presented a method to evaluate the performance of various state-of-the-art Wave Energy Converter technologies in terms of the expected Power Output Capacity Factor and Capture Width, when potentially working in the characteristic sea states found on the selected areas. The method is applied to a case study in the Archipelago of Azores. The data of the wave resource utilized comes from a hindcast model refined down to a spatial resolution of 0.05° that makes possible the detailed analysis and spatial comparison of results at insular local scales. The results intend to provide stakeholders and decision-makers with meaningful information about the suitable locations for the wave energy exploration and about the most efficient converter devices in such locations for the potential deployment of a wave energy exploration facility.
Coupled Time-Domain Hydro-Elastic Simulation for Submerged Floating Tunnel Under Wave Excitations
Authors: Jin Chungkuk , Kim Sung-Jae , Kim MooHyun
Published: October 2021

We develop a fully-coupled time-domain hydro-elasticity model for the Submerged Floating Tunnel (SFT) based on the Discrete-Module-Beam (DMB) method. Frequency-domain simulation based on 3D potential theory results in multibody’s hydrodynamic coefficients and excitation forces for tunnel sections. Subsequently, we build the time-domain model with the multibody Cummins equation and external stiffness matrix from the Euler-Bernoulli and Saint-Venant torsion theories. We establish the mooring line model with rod theory and couple components with translational springs at their respective connection locations. We then compare the dynamic motions, wave forces, and mooring tensions between the present and Morison-equation-based elastic models under regular wave excitations at different submergence depths. The present model is especially important for the shallowly submerged tunnel in which the Morison model shows exaggerated motions, especially at high-frequency range.
Prediction of the Financial Losses of Subsea Pipeline Failure
Authors: Aljaroudi Alireda A.
Published: October 2021

The consequences of subsea crude pipeline failure drastically affect the continuity of oil supply and the ability of operating companies to meet market demand. Moreover, it reduces clients’ confidence and reliance on operating companies. There are mainly two types of failures that severely affect the integrity and operability of a pipeline. These are the leakage caused by gradual thinning of the pipeline due to corrosion and the leakage caused by a rupture pressure. The first form of failure results in a constant slow leakage that go over time without being noticed. While the second form of failure takes place without warning which makes the restoration effort extremely difficult and time consuming. Both forms of failure result in delayed production, environmental damage, legal claims as well as financial losses that operating companies could incur. Moreover, leaked oil products adversely impact other industries which bring these industries into a halt. Such industries may include fishery, maritime transportation, and tourism industries. This paper presents a method for predicting the financial losses that a company could incur in the event a corroded pipeline undergoes the abovementioned failures. Basically, this method can be used as a standard estimating tool for predicting the financial losses if such events occur.
Early Engagement of ECA in Offshore Deepwater Pipeline Design
Authors: Zhou Daowu , Cao Lingjun , Sriskandarajah T. , Lewis Mark , Manso Daniel
Published: October 2021

Welding acceptance criteria derived through ECA is typically performed after the detailed design. The design loads, together with pipeline and girth weld material testing data, are inputs to ECA and used to evaluate the pipeline girth weld integrity for determining the criticality of potential weld flaws.

With ever increasing challenging environment (deepwater, HP/HT, aggressive fluid composition etc) in the oil and gas field, the fatigue damage and fracture failure may become a serious concern, consequently limiting the productivity of the pipeline fabrication. It is therefore essential to integrate ECA into the design loop to remove the uncertainty and risk to achieve a practically workable fabrication solution.

In this paper, a strategy to integrate early ECA into pipeline detailed design phase is presented. A case study in a deepwater subsea channel crossing demonstrates that an early ECA engagement effectively mitigates the significant fatigue and fracture risk and obtains workable welding acceptance criteria for fabrication.
Drift Motion of Floating Bodies Under the Action of Green Water
Authors: Tavakoli Sasan , Huang Luofeng , Babanin Alexander V.
Published: October 2021

Numerical simulations are peformed to model the dynamic motions of a free floating body exposed to water waves. The solid body has low freeboard and draft, and its upper deck can be washed by the steep waves. Thus, the green water phenomenon occurs as large waves interact with the floating body. The aim of the research is to improve the understanding of the green water emerging above the upper deck of a floating plate. A thin floating body with barriers is also modeled. For the case of the body equipped with barriers, no green water occurs. Green water has been seen to affect the wave field and the dynamic motions of the plate. It is observed that when water can wash the upper surface of the floating object, drift speed is slightly decreased as a proportion of the energy of waves is dissipated above the body. Water waves are seen to impact the upper surface of the thin floating body as the green water flows over its upper deck. Furthermore, water is seen to impact the plate as its front edge re-enters the water. The first water impact only occurs when the floating body is not equipped with any barrier. By sampling the numerical simulations, it is observed that the non-dimensional value of the impact pressure, resulting from the green water, is larger for the case of smaller wavelength.
Flow Field Inside and Around a Square Fish Cage Considering Fish School Swimming Pattern
Authors: Dong Shuchuang , Park Sang-gyu , Zhou Jinxin , Li Qiao , Yoshida Takero , Kitazawa Daisuke
Published: October 2021

The interaction between fluid and fish cage with stocked fish is extremely complex, including fluid and structure, as well as fluid and fish swimming behavior. The on-current swimming pattern of fish schools was found toward the incoming flow in the previous laboratory studies, which is different from the circular swimming pattern commonly observed in the farming site. In this study, a pseudo fish school structure model (PFS) was proposed to reproduce the five circular swimming patterns of farmed yellowtail, and to investigate the influence of fish school behaviors on the flow field inside and around a model square fish cage in laboratory experiments.

The results showed that the drag force acting on the square fish cage increased with the increase of the current speed for all fish school swimming patterns, but no clear difference was observed between the fish school swimming behavior patterns. Overall, the drag force of the square fish cage considering the farmed fish behavior decreased by 11.8%, compared to the drag force of the fish cage without PFS. The current speeds inside and downstream of the fish cage increased almost linearly with increasing current velocities. Compared with the case of the fish cage without PFS, the current speed inside the cage under motionless closely PFS (C0), revolving closely PFS (CR), motionless loosely PFS (L0) and revolving loosely PFS (LR) conditions changed by 10.8%, 9.4%, 65.8% and 39.7%, respectively. In addition, compared to the case of the fish cage without PFS, the current speeds under C0, CR, L0 and LR conditions decreased by 89.8%, 16.3%, 58.2%, and 31.9%, respectively, at 16.0cm downstream from the fish cage, and decreased by 69.2%, 19.4%, 62.7% and 26.3%, respectively, at 63.6cm downstream from the fish cage. Furthermore, the current speed distribution and relative horizontal turbulence intensity distribution inside and around the fish cage under different fish school swimming pattern was discussed. In the future, we will use live fish to conduct experiments to evaluate fish school models.
What Is Tsunami Earthquake?
Authors: Ebisuzaki Toshikazu
Published: October 2021

A tsunami earthquake is defined as an earthquake which induces abnormally strong tsunami waves compared with its seismic magnitude (Kanamori 1972; Kanamori and Anderson 1975; Tanioka and Seno 2001). We investigate the possibility that the surface waves (Rayleigh, Love, and tsunami waves) in tsunami earthquakes are amplified by secondly submarine landslides, induced by the liquefaction of the sea floor due to the strong vibrations of the earthquakes. As pointed by Kanamori (2004), tsunami earthquakes are significantly stronger in longer waves than 100 s and low in radiation efficiencies of seismic waves by one or two order of magnitudes. These natures are in favor of a significant contribution of landslides. The landslides can generate seismic waves with longer period with lower efficiency than the tectonic fault motions (Kanamori et al 1980; Eissler and Kanamori 1987; Hasegawa and Kanamori 1987). We further investigate the distribution of the tsunami earthquakes and found that most of their epicenters are located at the steep slopes in the landward side of the trenches or around volcanic islands, where the soft sediments layers from the landmass are nearly critical against slope failures. This distribution suggests that the secondly landslides may contribute to the tsunami earthquakes. In the present paper, we will investigate the rapture processes determined by the inversion analysis of seismic surface waves of tsunami earthquakes can be explained by massive landslides, simultaneously triggered by earthquakes in the tsunami earthquakes which took place near the trenches.
Pipe-in-Pipe Thermal Management System With Adjustable U-Value During Field Life
Authors: Jamieson Harvey , Stanning Alex , Legge Matthew , Sathananthan Ratnam
Published: October 2021

This paper details a new flowline thermal performance control system in which the overall heat transfer coefficient (U-value) of a pipe-in-pipe system can be varied. Large scale physical testing was carried out as part of the technology qualification to verify the system and design models developed. The solution is ideally suited for the increasing numbers of High Pressure High Temperature (HPHT) field developments being made; where the fluid temperature, pressure and flowrates will change significantly over the field life. It allows a new approach to flowline thermal design and operation to be taken for various types of field development.

A qualification program has been performed with independent verification body assessment of the work and results and confirms the predicted performance. This paper describes the qualification method to DNVGL-RP-A203 and associated Technology Readiness Level (TRL) assessment of the components.

The physical design of the system is presented along with examples of how benefits can be realised through its use.
A Study on the Main Parameters That Affects the Reliability of Fatigue Failure in a Marine Drilling Riser
Authors: das Chagas Bruno Luiz Barbosa , Kazuyuki Morooka Celso
Published: October 2021

Advances in subsea exploration in the oceans to discover new petroleum reservoirs and sometimes different kind of minerals at the seabed in ultra deepwater, continuously introduce new challenges in offshore drilling operations. This motivates the development of increasingly safe maritime operations.

In offshore petroleum, a marine drilling riser is the pipe that connects a wellhead at the sea bottom to a drillship at the sea surface, as an access to the wellbore. It serves as a guide for the drilling column with the drill bit and conductor to carry cuttings of rock coming from the wellbore drilling and its construction. Drilling riser is constantly exposed to adversity from the environment, such as waves, sea currents and platform motions induced by waves. These elements of the environment are prevailing factors that can cause a riser failure during deepwater drilling operations with undesirable consequences for the environment.

In the present work, key parameters that influence the probability of fatigue failure in a marine drilling riser are identified, and a parametric evaluation with those parameters are carried out. Dynamic behavior of a riser is previously calculated and fatigue damage is estimated. Afterwards, the First Order Reliability Method (FORM) is applied to determine the probability of fatigue failure on the riser. Fundamentals of the procedure are described, and results are illustrated through the analysis for a typical riser in deepwater drilling operation. Parametric evaluations are done observing points considered as critical along the riser length, and looking to the sensitivity of key parameters in the process. For this study, the SN curve from API guidelines is applied and accumulated fatigue damage is estimated from simulations of the stress time series and applying the Palmgren-Miner’s rule. Finally, the influence of each parameter in the reliability of fatigue failure is verified and discussions given.
Experimental Research on Vibration Characteristics of Laminated Composite Cantilever Beam
Authors: Yang Rui , Li Xiaobin , Li Hongxi
Published: October 2021

In this paper, the vibration characteristics of laminated composite cantilever beam is taken as the research object. Firstly, a vibration formula specific for laminated composite cantilever beam is derived, from which the low order natural frequency of laminated composite cantilever beam is calculated; Secondly, two experimental methods, electrical and optical measurement, are used to study the vibration characteristics of laminated composite cantilever beam, and the influence of different test methods, sensor types, number of measuring points and excitation methods on the test results are analyzed. Through the combination of theory and experiment, a test method that can be applied to the vibration test of composite material laminated structure cantilever beam is obtained. Based on the laser vibration measurement method in the optical method, the results show that the deviation between the experimental data and the theoretical solution is the smallest when the distance between the probe and the specimen is 0.5m and the sampling time is 5s by using the optical fiber vibrometer. The research content of this article can provide a reasonable reference for related vibration test research.
Full Scale Axial, Bending and Torsion Stiffness Tests of a Three Core HVAC Submarine Cable
Authors: Delizisis Panagiotis , Dolianitis Ioannis , Chatzipetros Dimitrios , Kanas Vasileios , Georgallis Georgios , Tastavridis Konstantinos , Stamelos Antonios , Angelis Efstratios
Published: October 2021

Submarine, export cables behave, to some point, as long, flexible cylindrical bodies. Their mechanical performance is crucial during laying and operating processes, which depends to a large extent on their stiffness. Although theoretical methods, used to estimate cable stiffness, are currently available, it is difficult to account for the various physical mechanisms involved, such as internal friction, residual torsion and ‘relaxation’ effects. These mechanisms are expected to affect cable stiffness and should be included some way. To represent more realistically cable stiffness, full-scale tests are performed in this paper. The deviation between theoretical and experimental values appears to be significant in certain cases: hence, non-realistic values for cable stiffness would occur if the stiffness estimation relied only on the theoretical methods. Interesting results, affording an in more depth insight and allowing for a better understanding of the cable mechanical performance, are presented in this paper.
Individual Blade Pitch Control for Alleviation of Vibratory Loads on Floating Offshore Wind Turbines
Authors: Pustina Luca , Pasquali Claudio , Serafini Jacopo , Lugni Claudio , Gennaretti Massimo
Published: October 2021

Among the renewable energy technologies, offshore wind energy is expected to provide a significant contribution for the achievement of the European Renewable Energy (RE) targets for the next future. In this framework, the increase of generated power combined with the alleviation of vibratory loads achieved by application of suitable advanced control systems can lead to a beneficial LCOE (Levelized Cost Of Energy) reduction. This paper defines a control strategy for increasing floating offshore wind turbine lifetime through the reduction of vibratory blade and hub loads. To this purpose a Proportional-Integral (PI) controller based on measured blade-root bending moment feedback provides the blade cyclic pitch to be actuated. The proportional and integral gain matrices are determined by an optimization procedure whose objective is the alleviation of the vibratory loads due to a wind distributed linearly on the rotor disc. This control synthesis process relies on a linear, state-space, reduced-order model of the floating offshore wind turbine derived from aero-hydroelastic simulations provided by the open-source tool OpenFAST. In addition to the validation of the proposed controller, the numerical investigation based on OpenFAST predictions examines also the corresponding control effort, influence on platform dynamics and expected blade lifetime extension. The outcomes show that, as a by-product of the alleviation of the vibratory out-of-plane bending moment at the blade root, significant reductions of both cumulative blade lifetime damage and sway and roll platform motion are achieved, as well. The maximum required control power is less than 1% of the generated power.
Predicting Wind Loads on the Topside of a Self-Propelled Wind Turbine Installation Jack-Up Using CFD
Authors: Sulaiman Zana
Published: October 2021

This paper presents the results of wind load computational fluid dynamics (CFD) calculations performed on the topside structures of a self-propelled wind turbine installation jack-up. The CFD calculations were performed for the jack-up topside structures with and without the deck load. An atmospheric boundary layer profile was applied for the model-scale calculations. The full range of heading angles was considered. The CFD results were validated through comparison with the wind tunnel tests which were carried out at the German-Dutch wind tunnels (DNW) in Marknesse, The Netherlands. Moreover, a comparison is presented between the applied boundary layer profiles throughout the CFD computational domain with those profiles measured in the wind tunnel. The CFD results were found to be in good agreement with the wind tunnel tests for the considered cases, verifying the feasibility of the CFD method as an important design tool for the prediction of wind loads during the design processes of these types of jack-ups.
Managing Pipeline Integrity and Dynamic Free Spans on Mobile Seabed in the Southern North Sea
Authors: Sequeiros Octavio , Ang Sze Yu , Clavin Craig , Upton Jon , Ho Cliff , van der Werf Auke
Published: October 2021

This paper describes the continuous improvement efforts to manage the integrity status of the Southern North Sea subsea pipeline system in the context of free spanning. The dynamic free-spanning threat is typically attributed to a mobile seabed. Current and wave action are constantly moving and eroding sediment by means of sand wave migration and scouring. It can lead to a fluctuation in span characteristics with respect to span length, span height and location over time. It makes pipeline integrity demonstration and spans remediation challenges. Focus areas include (1) identifying regions where operational pipelines are susceptible to critical span formation (2) understanding the broader context of seabed mobility, supported by several years of multibeam echo sound and met ocean data (3) risk-ranking & criticality of span formation (4) developing simplified calculation tool that allows fatigue damage to be estimated and accumulated for every location along the pipeline, conservatively (5) optimising and incorporating risk/event-based survey requirements (6) identification of suitable remediation solutions and developing a decision flow chart to facilitate selection of fit for purpose remediation solutions, with respect to span configuration and the surrounding seabed features. The outcome has improved the robustness of span management, reduced “reactive” span remediation activities, and allowed application of sound technical theory to allocate pipeline traffic light integrity status regarding the observed free spans.
Cementing Irregular Horizontal Wellbores
Authors: Renteria Alondra , Sarmadi Parisa , Frigaard Ian
Published: October 2021

In this work, we study the effect of borehole irregularities during primary cementing of a horizontal section of well. We use a simplified 2D gap-averaged model to compute the displacement of a drilling mud by a spacer within an elliptical annulus that represents an oval irregularity. We also present a series of 3D numerical simulations using a Volume of Fluid method to capture the interface between the fluids. The 3D model allows us to study the effects of more local irregularities such as wall roughness that can be imported from a caliper log.

The dynamics of the displacement of two fluids in a horizontal uniform circular annulus is governed by buoyancy, eccentricity and the rheology of the fluids. A positive density difference combined with a slow mean pumping speed promotes slumping of the second fluid towards the bottom of the annulus. Nevertheless, high eccentricity values (e = 1-standoff) are common due to the weight of the casing pulling downwards, opposing the buoyancy force. Finally, the rheology of the fluids is relevant to determine the presence of un-displaced layers of mud, e.g. at the walls.

The same competition described above holds true in the elliptical annulus. Results from the 2D gap-averaged model suggest that the elliptical shape incorporates an additional way of altering the velocity field around it. The effect is more evident when orienting the largest radius of the elliptical annulus at different angles. Results from 3D simulations show that the interface follows irregularities and the local roughness can improve the displacement by inducing secondary flows. However, enlargements result in poor displacement.
Topology Optimization Design of Filling Bodies in an Umbilical Based on Moving Morphable Components Theory
Authors: Wang Lifu , Yang Zhixun , Yan Jun , Shi Dongyan , Mao Yandong , Zhu Pengcheng
Published: October 2021

Umbilical is an indispensable link of offshore oil & gas resource development equipment for underwater production system, which are mainly composed of functional components such as steel tubes, electric cables and optical cables are in a helically wound structure. Filling bodies are required to support these functional components for improving anti-crushing capacity and fatigue life. Filling bodies have a significant impact on the mechanical and physical properties, which triggers the optimization design of filling bodies. However, the complexity of filling body space brings challenge to the optimization design. Moving Morphable Components (MMC) theory is introduced to topological optimization method in complicated filling body space with the objective of mechanical properties. The results show that the optimized filling bodies can effectively reduce structural weight with the same mechanical properties. Numerical models of cross-sections of umbilicals with the optimized filling bodies are constructed, the cross-sectional mechanical properties are compared with that under the initial filling body form, which can fully verify the feasibility and correctness of this optimization design strategy.
The Potential for Combining Floating Wind Turbines With Point Absorbing Wave Energy Converters
Authors: Skene David M. , Sergiienko Nataliia , Ding Boyin , Cazzolato Benjamin
Published: October 2021

The potential for coupling a cylindrical point absorber type wave energy converter (WEC) to a 5MW spar type floating offshore wind turbine is investigated. The wind and WEC system is modelled in the frequency domain and in two dimensions under the simplifying assumption that wind and waves propagate in the same direction. Coupling of the bodies is considered with respect to all theoretical combinations that might be achieved rather than a single specific design. Results are analysed with respect to the maximum power that the WEC coupling can achieve. It is shown that for mild waves the WEC can theoretically produce power in the range of 0.2 to 0.6 MW, its optimal dimensions are such that the draft and radius are approximately 18.8 m, and that obtaining this power tends to marginally amplify the pitch of the spar.
Optimization of a Torus-Shaped Wave Energy Converter Attached to a Hinged Arm
Authors: Kamarlouei Mojtaba , Hallak Thiago S. , Gaspar Jose F. , Calvário Miguel , Guedes Soares C.
Published: October 2021

This paper presents the adaptation of a torus wave energy converter prime mover to an onshore or nearshore fixed platform, by a hinged arm. An optimization code is developed to obtain the best torus and arm geometry, as well as the power take-off parameters, taking as objective function the maximization of total wave absorbed power. In this paper, the power take-off system is modelled as a simplified damper and spring system, where the parameters are optimized for the phase control of the wave energy converter in each sea state, whereas the optimization process is performed with a genetic algorithm. Finally, the optimal result for the productive sea state indicates that the absorbed power is relatively considerable while a better survivability performance is expected from a torus wave energy converter compared to a conventional truncated prime mover.
Experimental Study on Ultimate Strength of Novel Aluminum Alloy Stiffened Panel With Floating Girder
Authors: Sun Kun , Zhang Genglin , Zhu Ling , Xu Liang , Guo Kailing , Chen Haitao , Zhang Ping
Published: October 2021

With the rapid development of high-speed craft, the novel aluminum alloy stiffened panel with floating girder is widely used to achieve light weight ship hull for economic and high performance. While the mechanical properties of this novel structure are rarely studied. In order to investigate the differences of ultimate strength and collapse behavior between the novel aluminum stiffened panel with floating girder and fixed girder, the uniaxial compression experiments of novel aluminum stiffened panel with floating girder and fixed girder were conducted. Test apparatus were designed to accomplish simply supported boundary condition, then the uniaxial compression experiments were performed, eventually the ultimate strength and collapse behavior of different panels were analyzed. The results of the experiments show that the ultimate strength of novel aluminum stiffened panel with floating girder is higher than the panel with fixed girder under uniaxial compression, which means this type of novel aluminum alloy stiffened panel with floating girder applied on the high-speed craft can improve the ultimate strength of the vessel. Furthermore, it was witnessed that the collapse mode of stiffened panel with fixed girder is tripping of web while that of floating panel is bucking of girder.
Head Wave Simulation of a KCS Model Using OpenFOAM for the Assessment of Sea-Margin
Authors: Islam Hafizul , Guedes Soares C.
Published: October 2021

The paper presents calm water and head wave simulation results for a KRISO Container Ship (KCS) model. All simulations have been performed using the open source CFD toolkit, OpenFOAM. Initially, a systematic verification study has been performed using the ITTC guideline to assess the simulation associated uncertainties. After that, a validation study has been performed to assess the accuracy of the results. Next, calm water simulations have been performed with sinkage and trim free condition at varying speeds. Later, head wave simulations have been performed with heave and pitch free motion. Simulations were repeated for varying wave lengths to assess the encountered added resistance by the ship in design speed. The results have been validated against available experimental data. Finally, power predictions have been made for both calm water and head wave cases to assess the required propulsion power. The paper tries to assess the validity of using 25% addition as sea margin over calm water prediction to consider wave encounters.
Numerical Simulation Study on the Recovery Process of Autonomous Underwater Vehicle
Authors: Huang Weigang , Zhang Donglei , Yu Jiawei , He Tao , Wang Xianzhou
Published: October 2021

AUV (Autonomous Underwater Vehicle) recovery is considerably influenced by the nearby flow field and simulations of AUV in different motion paths in the wake of a submarine with a propeller are presented in this paper. A commercial CFD solver STAR CCM+ has been used to research the motion and flow characteristics of AUV, which using the advanced computational continuum mechanics algorithms. The DARPA (Defense Advanced Research Projects Agency) SUBOFF Submarine (L1 = 4.356m) propelled with INSEAN (Italian Ship Model Basin) E1619 propeller is used in this study, and the self-propulsion characteristics of the propeller at an incoming flow velocity of 2.75m/s are obtained through numerical simulation and results are compared with the available experimental data to prove the accuracy of the chosen investigation methodology. A grid/time-step convergence test is performed for verification study. AUV (L2 = 0.4356m) is a smaller-scale SUBOFF without a sail, which approaches the submarine in different motion paths in the submarine wake at a relative speed combined with the dynamic overlapping grid technology. The hydrodynamic performance of the AUV when approaching the submarine and the velocity distribution of the surrounding flow field are analyzed, which provides a useful reference for underwater recovery of the AUV.
Numerical Reproduction of the DeRisk Physical Model Tests on a Bottom-Fixed Foundation Exposed to Uni- and Multi-Directional Storm Sea States
Authors: Pierella Fabio , Bredmose Henrik , Dixen Martin , Ghadirian Amin
Published: October 2021

In this work, we compare the wave and loads statistics for two different sea states with a TP = 15.0[s] on a h = 33.0[m] depth, one with a 10-year return period (HS = 7.5[m]) and one with a 100-year (HS = 9.5[m]). For each sea state, a unidirectional and a multi-directional wave realization was measured experimentally and then reproduced numerically via a fully-nonlinear potential solver. The computed wave kinematics were used to calculate loads on a stiff cylinder with a diameter of D = 7.0[m], and compared with experiments. To perform a quantitative analysis, we extracted 30-minute maxima of the free surface elevation and in-line force, and fitted a Gumbel distribution via a Bayesian methodology. The analysis of the experiments showed that the extreme forcing on a stiff cylinder was larger in the 2D sea state than in the 3D sea state. As for the crest statistics, the 2D were higher than the 3D for the milder storm, while they were quite similar for the stronger storm, likely a consequence of the increased wave breaking, limiting the maximum achievable wave crests. The reproduction of the sea states and associated loads via a fully-nonlinear potential solver was overall able to predict the main trends. However, the 3D wave crests were overestimated for the milder sea state, probably due to a too soft breaking filter. The 2D forces for the larger sea state were on the other hand underestimated, likely due to the lack of a slamming load model. The analysis of the average wave shape leading to the extreme load events showed that in the experiments the extreme events are dominated by physics linked with the particle velocity, and hence in phase with the wave elevation signal, as drag loads, slamming loads and velocity-dependent free-surface intersection loads. On the other hand, in the simulations they are more inertia dominated, hence in phase with the kinematic acceleration signal.
Numerical Simulations of Flows Around Subsea Cover
Authors: Wan Jingyuan , Yin Guang , Liu Shengnan , Ong Muk Chen , Moen Petter
Published: October 2021

Glass reinforced plastic (GRP) subsea protection covers are often used to protect offshore pipelines, umbilicals and other important subsea structures from dropped objects released from offshore oil and gas and fishing activities. These covers are often subjected to waves. In the present study, flows around an oscillating GRP subsea cover and oscillatory flows around a stationary subsea cover are investigated using numerical simulations at three different KC numbers of 5, 11 and 20, which are representative for low, medium and large KC number regions. The simulations of flows around an oscillating subsea cover are used to compare with the experiments done by SINTEF Ocean (formerly MARINTEK) and validate the present numerical model. Two-dimensional (2D) simulations are carried out by solving the Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations combined with the k-ω Shear Stress Transport (SST) turbulence model. It is found that the hydrodynamic forces for the two cases (flows around the oscillating cover and oscillatory flows around the stationary cover) are almost the same, which verifies that the experimental tests of subsea covers with forced motions can be used to study hydrodynamic forces on the stationary cover subjected to waves. The horizontal and vertical force coefficients and the surrounding flow fields around the covers are discussed.
iPS cell therapy reported safe
Authors: Normile Dennis
Published: October 2021

Researchers no longer envision replacement tissues tailor-made from each patient's cells.
Impact of Erg11 Amino Acid Substitutions Identified in Candida auris Clade III Isolates on Triazole Drug Susceptibility
Authors: Williamson Benjamin , Wilk Adam , Guerrero Kevin D. , Mikulski Timothy D. , Elias Tony N. , Sawh Indira , Cancino-Prado Geselle , Gardam Dianne , Heath Christopher H. , Govender Nelesh P. , Perlin David S. , Kordalewska Milena , Healey Kelley R.
Published: October 2021

ERG11
sequencing of 28
Candida auris
clade III isolates revealed the presence of concomitant V125A and F126L substitutions. Heterologous expression of Erg11-V125A/F126L in
Saccharomyces cerevisiae
led to reduced fluconazole and voriconazole susceptibilities.
Face-to-face versus online clinically integrated EBM teaching in an undergraduate medical school: a pilot study
Authors: Kumaravel Bharathy , Stewart C , Ilic Dragan
Published: October 2021

Objectives

The aim of this study was to test the feasibility and effectiveness of two models (face-to-face vs online teaching) of clinically integrating evidence-based medicine (EBM) teaching in an undergraduate medical school.

Design and setting

A pilot study of face-to-face versus online EBM teaching.

Participants

This study focused on undergraduate medical students who entered the University of Buckingham Medical School MBChB course in 2016 (n=65). Of the 65 students, 45 received face-to-face teaching, while 20 received online teaching.

Main outcome measures

Feasibility was assessed by the ability to deliver the content, students’ engagement during teaching and their completion rates in formative assessments—Assessing Competency in EBM (ACE) tool, and educational prescriptions (EPs). Effectiveness of teaching for the two models was compared by evaluating students’ performance in the formative assessments and in the summative final professional examination and final year EBM objective structured clinical examination (OSCE).

Results

We had similar students’ engagement and completion rates in formative assessments in both models. Students receiving face-to-face teaching performed better in EPs (mean difference=−2.28, 95% CI: −4.31 to –0.26). There was no significant difference in performances in the ACE tool (mean difference=−1.02, 95% CI: −2.20 to 0.16); the written final professional exams (mean difference=−0.11, 95% CI: −0.65 to 0.44) and the EBM OSCE station (mean difference=−0.81, 95% CI: −2.38 to 0.74).

Conclusions

It was feasible to deliver both models of clinically integrated EBM teaching. While students in the face-to-face model scored higher in EPs; there was no significant difference between the two models of teaching as measured by performances in the ACE tool or the summative assessments.
‘Pneumonia has gone’: exploring perceptions of health in a cookstove intervention trial in rural Malawi
Authors: Ardrey Jane , Jehan Kate , Kumbuyo Caroline , Ndamala Chifundo , Mortimer Kevin , Tolhurst Rachel
Published: October 2021

Introduction

Air pollution through cooking on open fires or inefficient cookstoves using biomass fuels has been linked with impaired lung health and with over 4 million premature deaths per annum. However, use of cleaner cookstoves is often sporadic and there are indications that longer-term health benefits are not prioritised by users. There is also limited information about how recipients of cookstoves perceive the health benefits of clean cooking interventions. We therefore conducted a qualitative study alongside the Cooking and Pneumonia Study (CAPS).

Methods

Qualitative methods and the participatory methodology Photovoice were used in an in-depth examination of health perceptions and understandings of CAPS trial participants. Fifty participants in five CAPS intervention villages collected images about cooking. These were discussed in village-level focus groups and in interviews with 12 representative participants. Village community representatives were also interviewed. Four female and eight male CAPS fieldworkers took part in gender-specific focus groups and two female and two male fieldworkers were interviewed. A thematic content approach was used for data analysis.

Results

We found a disconnect between locally situated perceptions of health and the biomedically focused trial model. This included the development of potentially harmful understandings such as that pneumonia was no longer a threat and potential confusion between the symptoms of pneumonia and malaria. Study participants perceived health and well-being benefits including: cookstoves saved bodily energy; quick cooking helped maintain family harmony.

Conclusion

A deeper understanding of narratives of health within CAPS showed how context-specific perceptions of the health benefits of cookstoves were developed. This highlighted the conflicting priorities of cookstove intervention researchers and participants, and unintended and potentially harmful health understandings. The study also emphasises the importance of including qualitative explorations in similar complex interventions where potential pathways to beneficial (and harmful) effects, cannot be completely explicated through biomedical models alone.
The influence of the urban food environment on diet, nutrition and health outcomes in low-income and middle-income countries: a systematic review
Authors: Westbury Susannah , Ghosh Iman , Jones Helen Margaret , Mensah Daniel , Samuel Folake , Irache Ana , Azhar Nida , Al-Khudairy Lena , Iqbal Romaina , Oyebode Oyinlola
Published: October 2021

Introduction

Diet and nutrition are leading causes of global morbidity and mortality. Our study aimed to identify and synthesise evidence on the association between food environment characteristics and diet, nutrition and health outcomes in low-income and middle-income countries (LMICs), relevant to urban settings, to support development and implementation of appropriate interventions.

Methods

We conducted a comprehensive search of 9 databases from 1 January 2000 to 16 September 2020 with no language restrictions. We included original peer-reviewed observational studies, intervention studies or natural experiments conducted in at least one urban LMIC setting and reporting a quantitative association between a characteristic of the food environment and a diet, nutrition or health outcome. Study selection was done independently in duplicate. Data extraction and quality appraisal using the National Heart Lung and Blood Institute checklists were completed based on published reports using a prepiloted form on Covidence. Data were synthesised narratively.

Results

74 studies met eligibility criteria. Consistent evidence reported an association between availability characteristics in the neighbourhood food environment and dietary behaviour (14 studies, 10 rated as good quality), while the balance of evidence suggested an association with health or nutrition outcomes (17 of 24 relevant studies). We also found a balance of evidence that accessibility to food in the neighbourhood environment was associated with diet (10 of 11 studies) although evidence of an association with health outcomes was contradictory. Evidence on other neighbourhood food environment characteristics was sparse and mixed. Availability in the school food environment was also found to be associated with relevant outcomes. Studies investigating our other primary outcomes in observational studies of the school food environment were sparse, but most interventional studies were situated in schools. We found very little evidence on how workplace and home food environments are associated with relevant outcomes. This is a substantial evidence gap.

Conclusion

‘Zoning’ or ‘healthy food cart’ interventions to alter food availability may be appropriate in urban LMIC.

PROSPERO registration number

CRD42020207475.
Unilateral vocal cord adductor weakness: an atypical manifestation of motor neurone disease
Authors: Yogakanthi Saiumaeswar , Wools Christine , Mathers Susan
Published: October 2021

Background

Bulbar involvement is a recognised feature of motor neuron disease/amyotrophic lateral sclerosis (MND/ALS), both as a presenting complaint and as a consequence of advancing disease. Hoarseness and dysphonia have been associated with vocal cord abductor weakness. This is usually bilateral and has also been reported as the presenting clinical feature in a handful of patients with superoxide dismutase 1 (SOD1) gene mutations. Presentation with an isolated, unilateral vocal cord adductor weakness, however, is atypical and rare.

Case

In this report, we detail the case of a 38-year-old woman with dysphonia and a family history of an SOD1 mutation. Neurological features remained confined to the territory of the left vagus nerve for the next 12 months, before a more rapid rate of disease dissemination and progression.

Conclusions

This case highlights the importance of recognition of vocal cord palsy as an early manifestation of MND/ALS and the critical need for monitoring to recognise potential disease progression.
Characteristics of pharmacist’s interventions triggered by prescribing errors related to computerised physician order entry in French hospitals: a cross-sectional observational study
Authors: Videau Manon , Charpiat Bruno , Vermorel Céline , Bosson Jean-Luc , Conort Ornella , Bedouch Pierrick
Published: October 2021

Objectives

Computerised physician order entry (CPOE) systems facilitate the review of medication orders by pharmacists. Reports have emerged that show conception flaws or the misuse of CPOE systems generate prescribing errors. We aimed to characterise pharmacist interventions (PIs) triggered by prescribing errors identified as system-related errors (PISREs) in French hospitals.

Design

This was a cross-sectional observational study based on PIs prospectively documented in the Act-IP observatory database from January 2014 to December 2018.

Setting

PISREs from 319 French computerised healthcare facilities were analysed.

Participants

Among the 319 French hospitals, 232 (72.7%) performed SRE interventions, involving 652 (51%) pharmacists.

Results

Among the 331 678 PIs recorded, 27 058 were qualified as due to SREs (8.2%). The main drug-related problems associated with PISREs were supratherapeutic (27.5%) and subtherapeutic dosage (17.2%), non-conformity with guidelines/contraindications (22.4%) and improper administration (17.9%). The PI prescriber acceptation rate was 78.9% for SREs vs 67.6% for other types of errors. The PISRE ratio was estimated relative to the total number of PIs. Concerning the certification status of CPOE systems, the PISRE ratio was 9.4% for non-certified systems vs 5.5% for certified systems (p<0.001). The PISRE ratio for senior pharmacists was 9.2% and that for pharmacy residents 5.4% (p<0.001). Concerning prescriptions made by graduate prescribers and those made by residents, the PISRE ratio was 8.4% and 7.8%, respectively (p<0.001).

Conclusion

Computer-related prescribing errors are common. The PI acceptance rate by prescribers was higher than that observed for PIs that were not CPOE related. This suggests that physicians consider the potential clinical consequences of SREs for patients to be more frequently serious than interventions unrelated to CPOE. CPOE medication review requires continual pharmacist diligence to catch these errors. The significantly lower PISRE ratio for certified software should prompt patient safety agencies to undertake studies to identify the safest software and discard software that is potentially dangerous.