bluuebunny/crossref_metadata_2025 huggingface dataset:
A Synthesis Model for FLNG Design
Authors: Vieira Daniel Prata , Lavieri Rodrigo Sauri , Rocha Thiago Peternella , Dotta Raul , Rampazzo Fabiano , Nishimoto Kazuo
Published: October 2016

The increasing demand for natural gas is encouraging the development of novel floating units’ designs, capable of processing large quantities of hydrocarbon. These units called FLNG (Floating Liquefied Natural Gas) are facilities that produce, process and store liquefied natural gas (LNG) offshore. Once the topside and tanks of a FLNG are larger and more complex than the regular FPSO vessels, a design process considering these particularities must be used.

Once just few FLNG units are under construction and under design and not yet in operation, the information on the design first stages is poor. It is difficult to obtain a first hull sizing without taking in account the complexity mentioned above.

Thus, a set-based approach that works with sets of possible solutions that are analyzed and compared using a merit function in order to select the best and feasible solutions was used.

However, to produce a sufficiently large family of solutions, which includes most of the solution space, either the solution descriptions or the models must be simplified. From the computational point of view, the analyses of a family of design solutions basically relies on an initial parameterization of the object and a set of mathematical models that, as a group, will be referred as synthesis model. Additionally, some restrains are also applied to eliminate unfeasible solutions. The output of the synthesis model is a set of performance quantities that will be used to rank the solutions.

This design approach is particularly useful to deal with project trade-offs and to optimize multiple characteristics. Optimal solutions belongs to a surface (or a hyper surface) called Pareto boundary. This paper aims to achieve a platform design capable of producing, storing and offloading liquefied natural gas. It must safely survive under environmental conditions of Santos Basin in São Paulo, Brazil. In the same way, the design should guarantee the shortest downtime as well as keep costs, of acquisition and operation, as low as possible. Each of these characteristics must be quantified to allow a ranking of the generated solutions through an objective function.

Capacities, production rates, equipments, load distribution, environmental actions, stability, sea keeping and structural design estimates are the major areas to consider and will be related to one or more mathematical models, constraint and objective functions. The work will present a general overview of each model separately and how they work together, as well as examples of solutions and analyses depending on the input values.

It must be clear that this approach is applicable just in the early stages of design to obtain the first hull sizing. After that it is necessary to fall back on the traditional iteration process to rely in a feasible design.
On the Effects of Turbulence Modeling on the Fluid-Structure Interaction of a Rigid Cylinder
Authors: Rosetti Guilherme Feitosa , Vaz Guilherme , Fujarra André Luís Condino
Published: October 2016

The cylinder flow is a canonical problem for Computational Fluid Dynamics (CFD), as it can display several of the most relevant issues for a wide class of flows, such as boundary layer separation, vortex shedding, flow instabilities, laminar-turbulent transition and others. Several applications also display these features justifying the amount of energy invested in studying this problem in a wide range of Reynolds numbers. The Unsteady Reynolds Averaged Navier Stokes (URANS) equations combined with simplifying assumptions for turbulence have been shown inappropriate for the captive cylinder flow in an important range of Reynolds numbers. For that reason, recent improvements in turbulence modeling has been one of the most important lines of research within that issue, aiming at better prediction of flow and loads, mainly targeting the three-dimensional effects and laminar-turbulent transition, which are so important for blunt bodies. In contrast, a much smaller amount of work is observed concerning the investigation of turbulent effects when the cylinder moves with driven or free motions. Evidently, larger understanding of the contribution of turbulence in those situations can lead to more precise mathematical and numerical modeling of the flow around a moving cylinder. In this paper, we present CFD calculations in a range of moderate Reynolds numbers with different turbulence models and considering a cylinder in captive condition, in driven and in free motions. The results corroborate an intuitive notion that the inertial effects indeed play very important role in determining loads and motions. The flow also seems to adapt to the motions in such a way that vortices are more correlated and less influenced by turbulence effects. Due to good comparison of the numerical and experimental results for the moving-cylinder cases, it is observed that the choice of turbulence model for driven and free motions calculations is markedly less decisive than for the captive cylinder case.
Vortex-Induced Vibrations of a Riser With Design Variations
Authors: Zueck Robert F.
Published: October 2016

As meta-stable motions transverse to fluid flow in slender bluff-bodied structures, Vortex-Induced Vibrations (VIV) are mostly determined by three-dimensional (3D) geometric and relativistic changes that evolve in the structure. Simplistic models of the structure ignore these key physical principles.

In a 2014 OMAE paper, we introduced the key physical concepts for simulating VIV in a horizontal-oriented slender structure (pipeline). In a 2015 OMAE paper, we re-oriented the same structure vertically to simulate VIV in a vertical riser.

In this paper, one or more of the following variations in the vertically-oriented riser will be made, in order to judge the physical effect each variation has on the character and distribution of VIV along the riser:

• Cyclically move the upper end of the vertical riser

• Change into an S-shaped riser by adding weight/buoyancy

• Disconnect the lower end of the S-shaped riser

The simulations help show and reinforce the following mechanical concepts of VIV

• How gravity and fluid drag evolves a 3D shape in the riser

• How this shape creates specific structural flexibilities

• How these flexibilities set the stage for specific VIV

• How tension and end conditions are vital to VIV behavior
A 3D Higher Order Time Domain Rankine Panel Method for Wave-Current Interaction
Authors: Ruggeri Felipe , Watai Rafael A. , Simos Alexandre N.
Published: October 2016

The wave-current effects are very important in several offshore applications, for instance, the wave-drift-damping of a Turret moored FPSO. This papers presents the incorporation of current effects in the higher order time domain Rankine Panel Method on development in the Numerical Offshore Tank (TPN) at the University of São Paulo (USP) already introduced in [1]. The method is based on a perturbation theory to study first and second order effects, considering the geometry described using NURBS (Non Uniform Rational Basis Spline) and the potential function, free surface elevation, pressure etc by B-splines of arbitrary degree. The study is performed for a simplified geometry (sphere) and the results regarding a fixed hemisphere compared to other numerical methods considering both first and second order quantities are presented.
Comparative Study of Wave Run-Up and Slamming Occurrence for Multi-Unit Floating Offshore Wind Turbine Platform: Numerical Simulation vs. Model Test
Authors: Kang H. Y. , Jang H. K. , Kim M. H. , Kim K. H. , Hong K. Y.
Published: October 2016

A hybrid offshore renewable energy platform with multiple wind turbines and wave energy converters in a square-type host structure is proposed by Korea Research Institute of Ships and Ocean Engineering (KRISO). In this paper, we conduct a comparative study of wave run-up and slamming occurrence for the numerical simulations and physical 1:50 experiments. This hybrid renewable energy platform comprises a square frame structure with slender support structures as well as spread mooring system. Considering relative kinematics of the three-dimensional structure to waves especially for random seas, it may undergo not only vertical but also horizontal slamming impacts. Following the investigation of the wave run-up (airgap), the three-dimensional slamming occurrence is examined. Both regular waves and random waves are considered. The system identification of the numerical model is checked against the measured data from static-offset and free-decay tests. Following the systematic comparison between the experimental and numerical data, maximum wave run-up and the worst slamming occurrence in terms of the relative velocities are identified.
Axial Cyclic Behavior of a Bellow Joint for Pipelines
Authors: Wang Ning , Lu Guoxing , Lv Yang
Published: October 2016

Bellow joints are the critical part of pipelines systems buried undergrounds, which can undergo severe damage such as breaking, crushing, and bending, under strong earthquake actions. In our research work, a refined numerical analysis model of the bellow joint is studied using LS-DYNA program. Axial force and deformation of the single-wave bellow joint, under different ways of loading, such as axial compression, axial tension, one cyclic loading and cyclic loadings are investigated. The low cycle fatigue of the single-wave bellow joint is also researched. Moreover, the axial force and deformation characteristic of the multi-wave bellow joint are also studied. It shows that for the multi-wave bellow joint each wave deforms non-uniformly under axial compression, while distributed in each wave under axial tension. Through detailed numerical analysis, it turns out bellow joints have a good seismic performance.
Comparisons of DES and LES Turbulent Model for Simulation of Surface Ship Airwake
Authors: Li Congmin , Jiang Weijian , Cheng Jie , Yu Zongxin , Zhang Zhiguo
Published: October 2016

Due to the combination of the forward speed and the prevailing wind for surface ship traveling in the ocean, the airflow passing over the ship’s superstructure causes the formation of a disturbed flow region and the large speed gradients of the mean wind over the flight deck, known as the ship airwake. This airwake would cause significant influence on the performance of the helicopter rotor during its taking off or landing, increase the operation workload of the pilot and even cause safe-landing issues, especially when the wind sweeps over the deck. This paper presents a numerical simulation of flow across the ship superstructure using DES and LES turbulent model. The ship model used for simulation is the standard SF2 surface ship model with experimental measurement data which could be used for the CFD code validation. The simulation results are compared with the experimental measurement data, and the comparison with experimental results shows good match for both DES and LES turbulent models. Simulation results show that a series of vortex had been generated after the flow separation with asymmetric characteristics. From upstream to downstream, the vortex intensity decreases, but suddenly increases after encountering the chimney. The comparison between DES and LES turbulent models shows the similar flow field and vortex structure around the ship superstructure with same grid sets. Both DES and LES are superior to RANS in solving ship airwake. The comparisons of DES and LES turbulent models show that DES can reflect the separated flow with limited computational resource and LES simulation could get higher resolution of the fluid flow structure with enough computational resources.
The Principle of a Three-DOF Mechanism for Wave Energy Absorption
Authors: Chen Weixing , Meng Xiangdun , Gao Feng
Published: October 2016

As we all know, oceans have great wave power, and many types of wave energy converters (WECs) have been invented so far. Oscillating body systems are a major class of WECs which almost only have one degree of freedom (DOF). This paper presents a three-DOF mechanism which can extract the wave power from any wave directions. The three-DOF mechanism mainly consists of a four-bar linkage and a spherical joint, which are used to capture the heave motion and the pitch and roll motions of the oscillating body respectively. The power conversion principle of the WEC is proposed and the kinematics of the mechanism is derived. Hydraulic power take-off (PTO) systems are used, which are simplified as constant torques in this study. In the end, the power absorption performance of the WEC is presented based on the system dynamics. The results show that the rated power output of the WEC is 4.3MW, and the power output of the WEC is dependent on the wave directions.
Influence of the Lateral Pressure on the Collapse Strength of Continuous Stiffened Panels Under In-Plane Compression
Authors: Xu Ming Cai , Song Zhao Jun , Chen Si Xuan
Published: October 2016

It is vital to investigate the situations of ship bottom under longitudinal compressive load that results from the longitudinal bending of the hull girder, and at the same time considering the effect of lateral pressure. The periodical boundary conditions for two spans model are adopted to analyse the collapse behaviours of stiffened panels under combined axial thrust and lateral pressure. The material and geometric nonlinearities are considered in the simulation. The lateral pressure affect significantly on the collapse behaviours of the stiffened panels, which relate with the dimensions of stiffeners and plates.
Sheltering the Shore via Nearshore Oblique Seabed Bars
Authors: Couston Louis-Alexandre , Jalali Mir Abbas , Alam Mohammad-Reza
Published: October 2016

Periodic seabed undulations, such as nearshore sandbars, are known to reflect incoming surface waves of twice the wavelength by the so-called Bragg resonance mechanism. In view of this property, longshore seabed-mounted bars were proposed long ago as a means of coastal protection against the high momentum of incident oceanic waves. Many theoretical, computational, experimental and field measurements were conducted to understand their effectiveness in shielding the shore. The idea, nevertheless, proved impractical when Yu and Mei (JFM 2000, [1]) showed that due to an inevitable finite reflection from the shoreline, energy can get trapped in the area between the shoreline and the patch of bars eventually resulting in a much higher wave energy flux impinging the shoreline. Here we propose an arrangement of oblique bars that shelters the shore by diverting, rather than reflecting, shore-normal incident waves to the shore-parallel direction. A protected buffer zone is thus created at the shoreline. We show that this novel arrangement can very efficiently shelter the shore, is almost insensitive to the distance between the bottom corrugations and the shoreline, is relatively robust against frequency detuning, and will discuss that it can be designed to protect the shore against almost the entire broadband spectrum of incident waves.
Experimental Investigation of Cavity Patterns and Noise Characteristics
Authors: Ahn Byoung-Kwon , Jeong So-won , Kim Ji-Hye
Published: October 2016

When a marine propeller with the wing shape rotates at high speed underwater, local pressure on the blade decreases and various types of cavitation inevitably occur in where the local pressure falls below the vapor pressure. Cavity reduces the efficiency, erodes the propeller surface, and generate vibration and serious noise. Especially, underwater noise caused by cavitation is directly connected to the comfort of commercial ships and also the survivability of naval vessels. In order to reduce the occurrence of the cavitation and to design low noise propeller, it is demanded to figure out the correlation of noise characteristics with growth patterns of the cavity. In this paper, we observed global behavior of partial cavities generated on two-dimensional hydrofoils and made a map of cavity patterns. We also measured pressure fluctuations and investigated noise characteristics directly connected with the process of occurrence of the cavity.
Re-Evaluation of Suction Anchor Holding Capacity Based on Back Analysis of Undrained Shear Strength
Authors: Shin Yunsup , Langford Thomas , De Sordi Jerome
Published: October 2016

Suction anchors are used within mooring systems for a range of deep water floating structures. The number of suction anchor systems has increased rapidly over the last two decades due to ease of installation and a well-defined design approach. As with other offshore installations, anchor systems may be subjected to re-assessment during their operational lifetime, due to changes in loading, codes or other issues. Such assessment was performed recently for a floating storage unit (FSU) presently in service in the Norwegian Sea, where the geotechnical design of the anchors was re-evaluated.

The re-assessment of this storage unit allowed for a number of changes compared to the original design, including updated loads and load histories as well as changes to the safety factors. The geotechnical aspects of the design were also updated, including more refined analyses and a detailed review of the design soil profiles based on back-analysis of installation data.

This paper presents the work done related to the geotechnical holding capacity of the anchors during the assessment project. The work performed highlights the benefit of efficient FE analysis and a thorough evaluation of the soil properties and engineering behaviour.
Cofferdam and Hyperbaric “Live” Repair of Gas Pipeline Leaks
Authors: Tronskar Jens P. , Lee Chon Gee
Published: October 2016

Offshore pipelines may face many threats. Apart from internal and external corrosion third party threats represent major hazards to submarine pipelines. Recent pipeline leaks caused by third party as well as construction and installation have been repaired online in a two-step process involving installation of a leak clamp followed by a permanent repair by installation of a welded stand-off sleeve. The welding has depending on the water depth been executed in a hyperbaric habitat or in shallow water using purpose built cofferdams. A concept proposed by DNV GL has been successfully applied to repair of leaking submarine pipelines. To ensure the safety of the repair crew the concepts involves using a gas containment barrier installed over a traditional mechanical leak clamp. The gas containment barrier is either purged with inert gas or nitrogen or it is maintained with a constant inert gas pressure that is monitored continuously during the repair. In the event of a sudden gas leak into the gas containment barrier a pre-set pressure relief valve will open and dump the gas leak outside the habitat. This paper describes the details of a few cases of leaking submarine gas pipelines and the immediate causes of the leak, the repair method selection, the repair method details, cofferdam or hyperbaric welding qualification and execution. The paper also describes the various steps in the process to ensure that the pipeline damage is stable and that the repairs can be safely undertaken to restore the pipelines to their original design condition without reduction of pressure or flow rate. The paper describes the method of global and local finite element analyses as well as fracture mechanics assessment by FEA to assess the stability of the flaws causing the gas leaks. The pipelines in question have all been gas transmission lines carrying gas to gas fired power plants for which gas pressure reduction or shutdown were completely unacceptable. Future development is expected to involve development of remotely controlled repairs using similar concepts at water depths where diver/welders cannot be employed due to the various country regulations or simply because the water depths are too deep for saturation divers. Methodology according to DNV RP-A203 [1] is described for qualification of new technology for underwater pipeline repairs. Further references are made to the recent updates to the DNV RP-F113 Pipeline Subsea Repair [2] with regards to requirements for “live” pipeline repairs. The DNV RP-F113 refers to the PRCI Weld Thermal analyses [3] and requirements to perform full scale mock-up tests of the repair as part of the repair method qualification based on DNV OS-F101 Submarine Pipelines [4].
The Effect of Welding Residual Stress Distribution in Thickness Direction With Thick Steel Plate to Identification of Fracture Toughness
Authors: An Gyubaek , Woo Wanchuck , Park Jeongung
Published: October 2016

Along with the rapid increase in the size of welding structures, the steel plate used for structure has been increased in thickness. Especially, the growing capacity of large scale ships such as container ships has led to an increase in the thickness and the strength of steel plates for shipbuilding. The toughness and the resistance to brittle fractures of the steel plate tend to decrease for thick plates, which is a result of the so-called thickness effect. Steel plates with 80mm thickness were used and two welding processes, which are flux cored arc welding (FCAW) process and electron gas welding process (EGW), were used to produce full thickness weld joints. To evaluate of brittle crack propagation path, measurement of welding residual stress in both welded joint. In this study, it was aimed to investigate the effect of welding variables on the crack arrest toughness and crack propagation path of thick steel plate welds. Quantitative analysis by temperature gradient ESSO test was conducted to clarify the effect of welding variables for flux cored arc welding (FCAW) and electro gas welding (EGW) joint of thick steel plates with the thickness of 50 and 80mm. Also, welding residual stress was measured for evaluate of welding residual stress effect in both welding process in brittle crack propagation path using neutron science analysis.
Optimization of a Parametric FLNG in Finite Water Depth
Authors: Guha Amitava , Falzarano Jeffrey
Published: October 2016

Ultra large vessels such as recently engineered FPSOs and FLNG terminals require careful consideration of the effect of water depth in determining their motion characteristics. An efficient numerical implementation of the finite depth Green function, utilizing a series and integral form, has been developed. This is then incorporated in a three dimensional frequency domain panel method program capable of considering forward speed effects. The effect of water depth on the first and second order wave exciting forces and induced motions are studied.

An optimization framework is then developed combining an automated parametric FLNG hull form, the aforementioned in-house developed hydrodynamic analysis tool and an evolutionary optimization solver. In this paper, the principal methodologies used in the development of the finite depth Green function, solving the boundary value problem and key learning from the FLNG optimizations will be discussed.
Application of the Incorporated Meshing Technique to Non-Linear FE Analysis of Hull Girder Ultimate Strength
Authors: Li Chenfeng , Zhu Zhiyao , Ren Huilong , Zhou Xueqian
Published: October 2016

In the use of non-linear FE analyses for investigating the mechanical behavior and assessing the ultimate strength characteristics of ship hull structures, fine meshes can ensure the accuracy of results they are also, however, computationally expensive in terms of efficiency. Although the incorporated meshing technique, which can effectively reduce the computation time at almost no cost of accuracy, is a promising solution, it has not been systematically investigated. In this paper, the incorporated meshing technique is applied to the nonlinear FE analysis of hull girder ultimate strength based on the assumption of a certain stress distribution of ship section in the ultimate limit state. The computations are carried out with a variety of localized mesh refinements in the compressed zones. The results of ultimate strength analysis for a typical cargo hold shows that, compared to meshing with global refinement, the incorporated meshing technique can effectively improve the computational efficiency without sacrificing the numerical accuracy.
Verification of Riser Load Stacked on Stanchion Induced by Self Weight and Hull Acceleration
Authors: Kim So-Yoon , Choi Ki-Sub , Kim Myung-Hyun
Published: October 2016

Recently offshore installations for the development of gas and oil resources have moved toward the deeper sea and harsher environment. In this regard, there are increasing operational demands for offshore structures performing in depth with long distance transportation. Drill ships are one of the representative structures commonly employed for the development of energy resources in deep sea. However, these drilling systems are exposed to the various loadings and harsh environment. Therefore, current design code and standards are very conservative to take account of such conditions. The riser stanchions for the staking the riser are one of the structure that installed on the riser deck platform of drill ship. In transit or operating conditions, the riser load is applied to the stanchion. Therefore, the required strength of stanchion enough to withstand the riser loads and should be designed to meet owner and classification requirements. However, the currently practice design loads, which has been widely used in the shipyard and manufacture industries are too conservative resulting in excessive structural weight. In this regard, the purpose of this study is to propose a rational calculation procedure for the design of cost effective and lightweight stanchion structures.

This study used a pyramid stacking type of arrangement for the investigation of the effects of stanchion by riser self-weight and hull acceleration. First, the riser loads based on the current conventional design practice is compared with the results obtained by non-linear finite element analysis. In the finite element simulation, contact and damping conditions of stacked risers are explicitly considered. Second, the calculation of riser loads in transverse direction is not easy due to the difficulty associated with considering transverse hull acceleration. Therefore, a new design guideline is presented in a strength calculation of the stanchion structure against to the estimated design loads.
Methodology for Definition of New Sectors for DP Assisted Offloading Operations in Spread Moored Platforms
Authors: de Barros Orsolini Ana Luisa , Tannuri Eduardo Aoun , Santana Castelpoggi Felipe , Takashi Yuba Douglas Gustavo
Published: October 2016

This project defines a methodology for analyzing the proposition of expanding the operational sector of DP shuttle tankers in offloading operations in Spread Moored Platforms and still guaranteeing the operations’ safety.

The methodology consists at first in an evaluation of the reduction of the operation’s downtime as a function of sector angle increase by performing static analysis. These simulations are calibrated and validated by performing fast time dynamic simulations. Then, a Preliminary Risk Analysis is made to assess the potential hazards associated with the operation on the new expanded sector and, if necessary, some quantitative analyses take place. Finally, the methodology proposes that real time simulations are performed so that most critical conditions are recreated in the presence of an experienced Captain so he can give his opinion on how safe the operation would be.
Baseline Development of Rock Anisotropy Investigation Utilizing Empirical Relationships Between Oriented Physical and Mechanical Measurements and Drilling Performance
Authors: Abugharara Abdelsalam N. , Alwaar Abourawi M. , Butt Stephen D. , Hurich Charles A.
Published: October 2016

This paper describes a baseline investigation to confirm the isotropy of rocks material through physical and mechanical measurements followed by oriented drilling. This baseline is intended to evaluate drilling experiments in anisotropic rock materials to determine the significance of the anisotropy on drilling performance. The conducted tests include oriented measurements of compressional and shear wave velocities (Vp and Vs, respectively), density, Elastic Moduli, Point Load Strength Index (PLI), Indirect Tensile (IT) strength, and Unconfined Compressive Strength (UCS). The oriented laboratory drilling experiments were conducted under various pump flow rates and several weights on bit (WOB). In this work, an isotropic rock like material (RLM) was developed using Portland cement and fine-grained aggregate. The tested RLM specimens were of medium strength of ∼50 MPa. The RLM samples were cored in different orientations and then, tested and drilled according to these orientations. (e.g. 0°, 45° and 90°, representing horizontal, diagonal and vertical directions, respectively). Two main sets of lab tests were performed including pre-drilling and drilling tests. For the pre-drilling lab experiments, two main sets of tests were conducted to determine the physical and mechanical properties of samples (as outlined above) including PLI, IT, UCS, Vp, Vs, density and corresponding isotropic Dynamic Elastic Moduli. For the drilling tests, a vertical lab scale drilling rig was used with a 35 mm dual-cutter Polycrystalline Diamond Compact “PDC” bit. The drilling parameters involved were flow rates, nominal rotary speed of 300 rpm, and various WOB under atmospheric pressure. The relationships between the drilling data were analyzed including drilling rate of penetration (ROP), depth of cut (DOC), and corresponding effective WOB. The results of all mechanical, physical and drilling measurements and tests show consistent values indicating the isotropy of the tested rock material. This consistency verifies that the drilling tests are free of bias associated with drilling orientation.
Starting System for Darrieus Water Turbine of Tidal Stream Electricity Generation
Authors: Shimizu Seiji , Fujii Masayuki , Sumida Tetsuya , Sasa Kenji , Kimura Yasuhiro , Koga Eishi , Motogi Hisaya
Published: October 2016

Darrieus type vertical axis water turbine in a cylindrical shape which consists of some straight blades is simple, efficient and easy to install a generator upward. However, it has difficulty in starting revolution. As a method to cope with such a problem, a starting revolution assist mechanism was fabricated and set on a prototype of the turbine. Assist experiment was carried out. It resulted helping well the starting revolution. The improved prototype of tidal stream turbine can generate 1.4 W under a water flow of 1 m/s where impossible to self-start. Besides that, Darrieus water turbine’s generating torque property was investigated by the famous original experimental data of lift coefficient Cl and drag coefficient Cd for straight blades of NACA63 3-018 cross section. It was found that setting two or four blades in a turbine would help to improve the difficulty of starting revolution.
Multi-Objective Shape Optimization Design for LNG Cryogenic Helical Corrugated Steel Pipe
Authors: Yang Zhixun , Yan Jun , Lu Qingzhen , Chen Jinlong , Wu Shanghua , Wang Lidong , Yue Qianjin
Published: October 2016

The flexible cryogenic hose has been a favored alternative for offshore liquefied natural gas (LNG) exploitation recently, of which helical corrugated steel pipe is the crucial component with C shaped corrugation. Parametric finite-element models of LNG cryogenic helical corrugated pipe are presented based on 3D shell element in this paper. Taking account of nonlinearity such as cryogenic material and large geometric structural deformation, mechanical behavior characteristics results are obtained under axial tensional, bending and inner pressure loads. Meanwhile, the design parameters are determined for the shape optimization of structures of the flexible cryogenic hose through sectional dimension analysis, and sensitivity analysis is performed with changing geometric parameters. A multi-objective optimization with the object of minimizing stiffness and strength stress is formulated based on operation condition. Full factorial experiment and radial basis function (RBF) neural network are applied to establish the approximated model for the analysis of the structure. The Pareto optimal solution set and value range of parameters are obtained through NSGA-II GA algorithm under manufacturing and stiffness constraints. It provides a feasible optimal approach for the structural design of LNG cryogenic corrugated hose.
An evaluation of the perceptual quality of phase-aware single-channel speech enhancement
Authors: Krawczyk-Becker Martin , Gerkmann Timo
Published: October 2016

For the enhancement of single-channel speech corrupted by acoustic noise, recently short-time Fourier transform domain clean speech estimators were proposed that incorporate prior information about the clean speech spectral phase. Instrumental measures predict quality improvements for the phase-aware estimators over their conventional phase-blind counterparts. In this letter, these predictions are verified by means of listening experiments. The phase-aware amplitude estimator on average achieves a stronger noise reduction and is significantly preferred over its phase-blind counterpart in a pairwise comparison even if the clean spectral phase is estimated blindly on the noisy signal.
A cyclic di-GMP–binding adaptor protein interacts with a chemotaxis methyltransferase to control flagellar motor switching
Authors: Xu Linghui , Xin Lingyi , Zeng Yukai , Yam Joey Kuok Hoong , Ding Yichen , Venkataramani Prabhadevi , Cheang Qing Wei , Yang Xiaobei , Tang Xuhua , Zhang Lian-Hui , Chiam Keng-Hwee , Yang Liang , Liang Zhao-Xun
Published: October 2016

Binding of a bacterial second messenger to an adaptor protein directs the movement of a human pathogenic bacterium.
A short loop at the heart of a long RNA
Authors: Mushegian Alexandra A.
Published: October 2016

A specific structural motif in a long noncoding RNA mediates the interaction with a transcription factor to drive cardiac cell differentiation.
Signaling when to fill up
Authors: Gough Nancy R.
Published: October 2016

Enzymatic reduction by ERdj5 activates Ca
2+
-ATPase activity to replenish endoplasmic reticular calcium stores.
Evaluation of the Carba NP Test in Oregon, 2013
Authors: Morey Karim E. , Vega Robert , Cassidy P. Maureen , Buser Genevieve L. , Rayar Jaipreet K. , Myers Jeffrey A. , Weissman Scott J. , Beldavs Zintars G. , Pfeiffer Christopher D.
Published: October 2016

Carbapenem-resistant
Enterobacteriaceae
(CRE) are an urgent public health threat. We evaluated the capacity of the Carba NP test to detect carbapenemase production in 206 isolates: 143
Enterobacteriaceae
identified by Oregon's CRE surveillance program in 2013 and 63 known carbapenemase-positive organisms. Overall, test sensitivity and specificity were 89% (59/66 isolates; 95% confidence interval [CI], 81 to 97%) and 100% (140/140 isolates; 95% CI, 98 to 100%), respectively. All KPC, NDM-1, VIM, and IMP producers but no (0/7 isolates) OXA-48-like strains were Carba NP positive prior to a
post hoc
protocol modification. We subsequently incorporated Carba NP into Oregon's CRE screening algorithm.
Mitogen-Activated Protein Kinase 2 Signaling Shapes Macrophage Plasticity in Aggregatibacter actinomycetemcomitans-Induced Bone Loss
Authors: Herbert Bethany A. , Steinkamp Heidi M. , Gaestel Matthias , Kirkwood Keith L.
Published: October 2016

Aggregatibacter actinomycetemcomitans
is associated with aggressive periodontal disease, which is characterized by inflammation-driven alveolar bone loss.
A. actinomycetemcomitans
activates the p38 mitogen-activated protein kinase (MAPK) and MAPK-activated protein kinase 2 (MK2) stress pathways in macrophages that are involved in host responses. During the inflammatory process in periodontal disease, chemokines are upregulated to promote recruitment of inflammatory cells. The objective of this study was to determine the role of MK2 signaling in chemokine regulation during
A. actinomycetemcomitans
pathogenesis. Utilizing a murine calvarial model,
Mk2

+/+

and
Mk2
−/−
mice were treated with live
A. actinomycetemcomitans
bacteria at the midsagittal suture. MK2 positively regulated the following macrophage RNA:
Emr1
(F4/80),
Itgam
(CD11b),
Csf1r
(M-CSF Receptor),
Itgal
(CD11a),
Tnf
, and
Nos2
. Additionally, RNA analysis revealed that MK2 signaling regulated chemokines CCL3 and CCL4 in murine calvarial tissue. Utilizing the chimeric murine air pouch model, MK2 signaling differentially regulated CCL3 and CCL4 in the hematopoietic and nonhematopoietic compartments. Bone resorption pits in calvaria, observed by micro-computed tomography, and osteoclast formation were decreased in
Mk2
−/−
mice compared to
Mk2

+/+

mice after
A. actinomycetemcomitans
treatment. In conclusion, these data suggest that MK2 in macrophages contributes to regulation of chemokine signaling during
A. actinomycetemcomitans
-induced inflammation and bone loss.
Serine-Aspartate Repeat Protein D Increases Staphylococcus aureus Virulence and Survival in Blood
Authors: Askarian Fatemeh , Uchiyama Satoshi , Valderrama J. Andrés , Ajayi Clement , Sollid Johanna U. E. , van Sorge Nina M. , Nizet Victor , van Strijp Jos A. G. , Johannessen Mona
Published: October 2016

Staphylococcus aureus
expresses a panel of cell wall-anchored adhesins, including proteins belonging to the microbial surface components recognizing adhesive matrix molecule (MSCRAMM) family, exemplified by the serine-aspartate repeat protein D (SdrD), which serve key roles in colonization and infection. Deletion of
sdrD
from
S. aureus
subsp.
aureus
strain NCTC8325-4 attenuated bacterial survival in human whole blood
ex vivo
, which was associated with increased killing by human neutrophils. Remarkably, SdrD was able to inhibit innate immune-mediated bacterial killing independently of other
S. aureus
proteins, since addition of recombinant SdrD protein and heterologous expression of SdrD in
Lactococcus lactis
promoted bacterial survival in human blood. SdrD contributes to bacterial virulence
in vivo
, since fewer
S. aureus
subsp.
aureus
NCTC8325-4 Δ
sdrD
bacteria than bacteria of the parent strain were recovered from blood and several organs using a murine intravenous infection model. Collectively, our findings reveal a new property of SdrD as an important key contributor to
S. aureus
survival and the ability to escape the innate immune system in blood.
An Intracellular Peptidyl-Prolyl
cis
/
trans
Isomerase Is Required for Folding and Activity of the Staphylococcus aureus Secreted Virulence Factor Nuclease
Authors: Wiemels Richard E. , Cech Stephanie M. , Meyer Nikki M. , Burke Caleb A. , Weiss Andy , Parks Anastacia R. , Shaw Lindsey N. , Carroll Ronan K.
Published: October 2016

Staphylococcus aureus
is an important human pathogen that relies on a large repertoire of secreted and cell wall-associated proteins for pathogenesis. Consequently, the ability of the organism to cause disease is absolutely dependent on its ability to synthesize and successfully secrete these proteins. In this study, we investigate the role of peptidyl-prolyl
cis/trans
isomerases (PPIases) on the activity of the
S. aureus
secreted virulence factor nuclease (Nuc). We identify a staphylococcal cyclophilin-type PPIase (PpiB) that is required for optimal activity of Nuc. Disruption of
ppiB
results in decreased nuclease activity in culture supernatants; however, the levels of Nuc protein are not altered, suggesting that the decrease in activity results from misfolding of Nuc in the absence of PpiB. We go on to demonstrate that PpiB exhibits PPIase activity
in vitro
, is localized to the bacterial cytosol, and directly interacts with Nuc
in vitro
to accelerate the rate of Nuc refolding. Finally, we demonstrate an additional role for PpiB in
S. aureus
hemolysis and demonstrate that the
S. aureus
parvulin-type PPIase PrsA also plays a role in the activity of secreted virulence factors. The deletion of
prsA
leads to a decrease in secreted protease and phospholipase activity, similar to that observed in other Gram-positive pathogens. Together, these results demonstrate, for the first time to our knowledge, that PPIases play an important role in the secretion of virulence factors in
S. aureus
.

IMPORTANCE
Staphylococcus aureus
is a highly dangerous bacterial pathogen capable of causing a variety of infections throughout the human body. The ability of
S. aureus
to cause disease is largely due to an extensive repertoire of secreted and cell wall-associated proteins, including adhesins, toxins, exoenzymes, and superantigens. These virulence factors, once produced, are typically transported across the cell membrane by the secretory (Sec) system in a denatured state. Consequently, once outside the cell, they must refold into their active form. This step often requires the assistance of bacterial folding proteins, such as PPIases. In this work, we investigate the role of PPIases in
S. aureus
and uncover a cyclophilin-type enzyme that assists in the folding/refolding of staphylococcal nuclease.
SecA Cotranslationally Interacts with Nascent Substrate Proteins
In Vivo
Authors: Huber Damon , Jamshad Mohammed , Hanmer Ruby , Schibich Daniela , Döring Kristina , Marcomini Isabella , Kramer Günter , Bukau Bernd
Published: October 2016

SecA is an essential component of the Sec machinery in bacteria, which is responsible for transporting proteins across the cytoplasmic membrane. Recent work from our laboratory indicates that SecA binds to ribosomes. Here, we used two different approaches to demonstrate that SecA also interacts with nascent polypeptides
in vivo
and that these polypeptides are Sec substrates. First, we photo-cross-linked SecA to ribosomes
in vivo
and identified mRNAs that copurify with SecA. Microarray analysis of the copurifying mRNAs indicated a strong enrichment for proteins containing Sec-targeting sequences. Second, we used a 2-dimensional (2-D) gel approach to analyze radioactively labeled nascent polypeptides that copurify with SecA, including maltose binding protein, a well-characterized SecA substrate. The interaction of SecA with nascent chains was not strongly affected in cells lacking SecB or trigger factor, both of which also interact with nascent Sec substrates. Indeed, the ability of SecB to interact with nascent chains was disrupted in strains in which the interaction between SecA and the ribosome was defective. Analysis of the interaction of SecA with purified ribosomes containing arrested nascent chains
in vitro
indicates that SecA can begin to interact with a variety of nascent chains when they reach a length of ∼110 amino acids, which is considerably shorter than the length required for interaction with SecB. Our results suggest that SecA cotranslationally recognizes nascent Sec substrates and that this recognition could be required for the efficient delivery of these proteins to the membrane-embedded Sec machinery.

IMPORTANCE
SecA is an ATPase that provides the energy for the translocation of proteins across the cytoplasmic membrane by the Sec machinery in bacteria. The translocation of most of these proteins is uncoupled from protein synthesis and is frequently described as “posttranslational.” Here, we show that SecA interacts with nascent Sec substrates. This interaction is not dependent on SecB or trigger factor, which also interact with nascent Sec substrates. Moreover, the interaction of SecB with nascent polypeptides is dependent on the interaction of SecA with the ribosome, suggesting that interaction of the nascent chain with SecA precedes interaction with SecB. Our results suggest that SecA could recognize substrate proteins cotranslationally in order to efficiently target them for uncoupled protein translocation.
Retinal microvascular network geometry and cognitive abilities in community-dwelling older people: The Lothian Birth Cohort 1936 study
Authors: McGrory Sarah , Taylor Adele M , Kirin Mirna , Corley Janie , Pattie Alison , Cox Simon R , Dhillon Baljean , Wardlaw Joanna M , Doubal Fergus N , Starr John M , Trucco Emanuele , MacGillivray Thomas J , Deary Ian J
Published: October 2016

Aim

To examine the relationship between retinal vascular morphology and cognitive abilities in a narrow-age cohort of community-dwelling older people.

Methods

Digital retinal images taken at age ∼73 years from 683 participants of the Lothian Birth Cohort 1936 (LBC1936) were analysed with Singapore I Vessel Assessment (SIVA) software. Multiple regression models were applied to determine cross-sectional associations between retinal vascular parameters and general cognitive ability (g), memory, processing speed, visuospatial ability, crystallised cognitive ability and change in IQ from childhood to older age.

Results

After adjustment for cognitive ability at age 11 years and cardiovascular risk factors, venular length-to-diameter ratio was nominally significantly associated with processing speed (β=−0.116, p=0.01) andg(β=−0.079, p=0.04). Arteriolar length-to-diameter ratio was associated with visuospatial ability (β=0.092, p=0.04). Decreased arteriolar junctional exponent deviation and increased arteriolar branching coefficient values were associated with less relative decline in IQ between childhood and older age (arteriolar junctional exponent deviation: β=−0.101, p=0.02; arteriolar branching coefficient: β=0.089, p=0.04). Data are presented as standardised β coefficients (β) reflecting change in cognitive domain score associated with an increase of 1 SD unit in retinal parameter. None of these nominally significant associations remained significant after correction for multiple statistical testing.

Conclusions

Retinal parameters contributed <1% of the variance in the majority of associations observed. Whereas retinal analysis may have potential for early detection of some types of age-related cognitive decline and dementia, our results present little evidence that retinal vascular features are associated with non-pathological cognitive ageing.
ULTRASOUND MEASUREMENT OF CHEST WALL THICKNESS IN ELITE RUGBY PLAYERS; A COMPARISON BETWEEN THE NEEDLE THORACOCENTESIS SITES
Authors: Jones C , Adejuwon A
Published: October 2016

Aims

There are no known published studies to support current pitch side guidelines for the management of a tension pneumothorax in a sporting population (1). Temporary management of this condition involves needle thoracocentesis (NT) at the 2nd intercostal space mid clavicular line (2MCL). The 5th intercostal space anterior axillary line (5AAL) has been suggested as an alternative site.1 The aim of the study was to compare chest wall thickness (CWT) at the 2MCL and the 5AAL of an elite rugby union team. The secondary aim was to calculate potential NT failure between player positions; Forwards and Backs.

Methods

Potential failure was calculated by comparing CWT in relation to both a standard cannula length of 4.5 cm and the advised needle length of 5.0 cm. Ultrasound recorded three measurements of CWT at the 2MCL and 5AAL on both sides of the thorax.

Results

Forty-three male players with a mean age of 25.7 years participated. Forwards demonstrated a thicker CWT than Backs at both sites. The mean CWT at 2MCL was 3.78 cm in Forwards and 3.30 cm in Backs. The mean CWT at the 5AAL site was uniformly thinner and measured 3.16 cm in Forwards and 2.40 cm in Backs. 22.2% (n=6) of Forwards had a CWT greater then 4.5 cm. 11.1% (n=3) of Forwards had a CWT greater then 5.0 cm at 2MCL. For all player positions the CWT at the 5AAL was less than 5.0 cm.

Conclusions

Forward position rugby players had a greater CWT than Back players. One in ten Forward players had the potential to fail NT in accordance to suggested guidelines. CWT at the 5AAL was significantly thinner (p<0.05) than at the 2MCL for all players and may be a more suitable NT site for Forward players.