Anchor Chain Research Articles

基于静力学分析的系泊系统状态浅析

系泊系统分析是通过获取系泊系统的自身参数以及周围环境参数，对系泊系统的钢桶和各节钢管的倾斜角度、浮标的吃水深度、和游动区域进行求解，从而判断系泊系统的工作状态。首先，通过对系泊系统整体和各部件的力学分析建立模型，并引入悬链线方程求解锚链方程，运用递推方程求解未知参数。其次，将数学建模题目中已知参数代入，利用穷举法求解临界风速，判断系统运动状态，在不同情况下分别运用MATLAB编程求解。最后，利用穷举法求出重物球重量变化范围。从而实现系泊系统状态的判断与分析。 Through the mooring system’s own parameters and the surrounding environment parameters, mooring system analysis is to solve steel drums and sections of the steel pipe tilt angle, buoy of the draft depth, and swimming area of the mooring system, which determine the working state of the mooring system. Firstly, the model is established by static analysis of the mooring system and the components, and the catenary line equation is introduced to solve the equation of anchor chain, recurring equations to solve the unknown parameters. Secondly, we substitute the known parameters of subject into the equation, and use the exhaustive method to solve the critical wind speed and to determine the state of motion of the system. In different circumstances, we respectively use MATLAB to solve the equation. Finally, the range of heavy weight is determined by exhaustive method so as to realize the state judgment and analysis of mooring system.

Study on interaction between soil and anchor chain with finite element method

With the development of offshore engineering, deeply embedded anchors are needed to be penetrated to appreciable depth and attached at the pad-eye. The interaction between anchor chain and soil is a very complex process and has not been thoroughly understood yet. In this paper, the finite element method (FEM) was used to study the interaction of soil-chain system. Results of the analysis show that when the attachment point is at a shallow depth, the load-development characteristics of the chain from FEM are in good agreement with that from the model tests and theoretical analysis. But with the depth increment, the results are different obviously in different methods. This phenomenon is resulted from a variety of reasons, and the plastic zone around the chain was studied to try finding the mechanism behind it. It could be seen that the plastic zone extended in different modes at different depths of attachment points. The interaction between the soil and anchor chain makes the load acting on the anchor decrease, but the soil disturbed surrounding the chain increases the anchor failure possibility. When the anchor bearing capacity is evaluated, these two factors should be considered properly at the same time.

Static pullout resistance of anchor chains in cohesionless soil—laboratory testing

ABSTRACTThis paper investigates the static pullout resistance of anchor chains embedded into cohesionless soil. The anchor chains, which are made of steel, were buried into Jumunjin sand whose relative density was set to approximately 60%. The anchor chains were horizontally pulled out through a displacement of 70 mm in laboratory model tests. Three different embedment depths and seven different numbers of chain links were adopted. The pullout resistance of the anchor chains was found to increase with increasing embedment depth and the number of anchor chain links. The measured resistance was significantly higher than the calculated frictional resistance, implying that the passive resistance at the front of the anchor chain significantly contributes to the pullout resistance. The contribution of the passive resistance tends to decrease with increasing number of chain links.

Inverse catenary load attenuation along embedded ground chain of mooring lines

The present paper presents an investigation of the static load attenuation emerging from the soil frictional forces acting on the embedded part of an anchor chain. Mooring line tension makes the embedded chain segment to develop an inverse catenary shape between the deep down point (DDP) and the padeye. Both the shape of the catenary and the mobilized frictional forces have significant influence on the total loading capacity of the anchoring system. The work is based on laboratory tests using a scale reduced model, designed to evaluate the catenary development and the load attenuation in respect to the installation depth, nominal chain angle and soil mechanical properties. As the experiments comprehend both loading and unloading cycles, the results provide a substantial database for confrontation of constitutive models for soil-chain interaction. In the literature, the usual assumption to relate frictional (F) and transversal (Q) forces in a catenary segment, ds, is a direct proportionality. However, present results indicate that such a simple relation is an oversimplification of a far more complex relation that cannot be accurately used for modeling the catenary development. Besides an hysteretic behavior, the mean relation F/Q presents a dependence on the undrained soil shear strength, su, also contradicting the usual assumption that F and Q are both linearly dependent on this parameter.

Dynamics of a taut mooring line accounting for the embedded anchor chains

Mooring line responses have been widely analyzed in the past three decades. Most of these studies have assumed that the anchor point is fixed at the seabed. However, with the increasingly employment of the taut mooring system, the suction anchors are more and more often used. To achieve an appropriate hold capacity, the anchor points are embedded several meters beneath the seabed, making part of the mooring lines embedded, whereby complex soil-chain interaction occurs. The soil-chain interaction has not been incorporated in previous mooring dynamic analyses. In this study, a dynamic method using the lumped mass model was used to consider the soil-chain interaction for the embedded anchor chain. Validation has been conducted against both analytical results and those from the commercial code. To clarify the influence of the embedded chain, case studies were conducted to compare the line's dynamic response at the anchor point, touchdown point and fairlead in three different configurations. Recommendations have been given on two frequently-used in simplifying the mooring dynamic calculation.

The design and analysis of the mechanical property test platform frame for marine structures

In order to realize mechanical properties test of the emergency towing arrangements, anchor chain and other large marine components, a large-tonnage and multi-function horizontal tension test platform is put forward in this paper. The paper analyzes the disadvantages of the frame structure of the existing experimental platform and designs the composite structure of the concrete and steel. The steel has good elasticity and toughness, the concrete has good performance of high rigidity and compression resistance, so the composite structure takes the advantages of both. The sharp of the frame is like “L”, which can be used to testing different projects. The paper gives the detailed size and analysis procedure of the frame. And it finds a more reasonable structure by means of finite element to analyze and optimize. The frame structure has the advantages of low weight and cost. The platform has been installed in Zhoushan, China successfully.

The Molecular Mechanism Underlying Recruitment and Insertion of Lipid-Anchored LC3 Protein into Membranes

Lipid modification of cytoplasmic proteins initiates membrane engagement that triggers diverse cellular processes. Despite the abundance of lipidated proteins in the human proteome, the key determinants underlying membrane recognition and insertion are poorly understood. Here, we define the course of spontaneous membrane insertion of LC3 protein modified with phosphatidylethanolamine using multiple coarse-grain simulations. The partitioning of the lipid anchor chains proceeds through a concerted process, with its two acyl chains inserting one after the other. Concurrently, a conformational rearrangement involving the α-helix III of LC3, especially in the three basic residues Lys65, Arg68, and Arg69, ensures stable insertion of the phosphatidylethanolamine anchor into membranes. Mutational studies validate the crucial role of these residues, and further live-cell imaging analysis shows a substantial reduction in the formation of autophagic vesicles for the mutant proteins. Our study captures the process of water-favored LC3 protein recruitment to the membrane and thus opens, to our knowledge, new avenues to explore the cellular dynamics underlying vesicular trafficking.

Математическое моделирование взаимосвязанных электромеханических систем непрерывной подгруппы клетей прокатного стана. Часть 1. Разработка математической модели

The paper considers development of the mathematical model of the interrelated stands of the continuous sub-group belonging to the roughing train of the wide-strip hot-rolling mill. The paper substantiates the task of studies on repeated dynamic processes occurring in the electromechanical systems of the universal mill stand edging rolls at the strip gripping by rolls of the tandem horizontal roll stand. The dynamic torque is registered to be 2 to 2.5 times greater than the steady mill torque in this mode. The main reason for occurring repeated shock loads is incoordination of the speed of the strip leaving the edging stand rolls and linear speed of the horizontal stand rolls. To study the transfer of the kinetic energy to the motor shaft of the previous stand it is proved that developing the improved mathematical model of the deformation zone is reasonable. We propose to develop this model in reliance on the equation of the energy conservation at rolling. In the paper there is the structural diagram of the mathematical model of the interrelated electric drives of the edging and horizontal rolls of the three-stand 2,000 mm mill trains of OJSC Magnitogorsk Iron and Steel Works. The paper offers analytic expressions for calculation of the power supplied to the deformation zone from the roll drive motor side, the power supplied due to the metal front tension (looping) and rear looping (tension), the power consumed at gauge forming and power of the slipping friction power. In connection with it, the metal behavior in the deformation zone has been studied; mathematical expressions of the changing elementary velocities of points on the surfaces of the entrance and exit sections are provided. The paper gives dependencies of the metal sliding related to the rolls and slipping friction powers for lead and lag areas obtained with regard to the changing area of the proceeded metal and its resistance to deformation. Based on the obtained expressions, the structural diagram of the deformation zone model has been developed. Analytical and operator expressions for modeling tension and looping forces, as well as structure of the model describing elastic properties of the strip in the inter-stand space are presented. The paper delivers the structure of the mathematical model for electric drive speed control system based on the known equations of the anchor chain of the DC motor. After the comparison of the transient processes of the electric drive coordinates and rolling settings obtained at the modeling and oscillography at the mill the conformity of the developed model to the studied object has been proved. The provided mathematical model is recommended to be applied for examination of the power interaction of the electromechanical rolling mill systems, as well as for the analysis of the dynamical modes at the strip gripping by the edging and horizontal stand rolls.

A tool for ROV-based seabed friction measurement

This paper describes a new device for measuring seabed sliding resistance in situ, and provides an associated interpretation procedure. The device is designed to use a work class ROV as a testing platform to allow measurements to be obtained without use of a specialized geotechnical survey platform. The measurements are to assist pipeline design or analysis of the sliding resistance of other on-bottom infrastructure such as anchor chains. The device has been trialled using three tools: a flat plate, a cylindrical pipe section and a length of chain. The tools are dragged axially along the seabed using the ROV thrusters or a separate hydraulic actuator. An interpretation technique has been developed to estimate the passive resistance mobilized by the faces of the tools to eliminate end effects and to account for shape effects such as wedging. Onshore-trial tests were performed in a bed of dry sand. The individual tools exhibited different overall coefficients of friction, but the back-analysis method yielded equal interface friction angles acting on all three devices, indicating internal consistency. The interface friction angle also matched shear box test results. These outcomes confirm the correct operation of the device in drained seabed conditions, and yield useful information on the sliding resistance of pipes and chains. In addition, the back-analysis method allows measurements from one shape of tool to be used to estimate the response of other objects.

Membrane curvature enables N-Ras lipid anchor sorting to liquid-ordered membrane phases.

Trafficking and sorting of membrane-anchored Ras GTPases are regulated by partitioning between distinct membrane domains. Here, in vitro experiments and microscopic molecular theory reveal membrane curvature as a new modulator of N-Ras lipid anchor and palmitoyl chain partitioning. Membrane curvature was essential for enrichment in raft-like liquid-ordered phases; enrichment was driven by relief of lateral pressure upon anchor insertion and most likely affects the localization of lipidated proteins in general.

Incorporating Shank Resistance into Prediction of the Keying Behavior of Suction Embedded Plate Anchors

The suction embedded plate anchor (SEPLA) is a promising deepwater anchoring solution that uses a suction caisson to install a plate anchor vertically to a precise depth within the seabed. The plate anchor is then rotated from its vertical position toward an inclination approximately normal to the load applied by the mooring line in a process known as keying. This configuration reduces the embedment depth and, in typically increasing strength with depth soils, diminishes the installed capacity of the anchor. Therefore, an accurate prediction of the keying behavior of SEPLAs is crucial for offshore operations. Recently, plasticity approaches that combine a yield surface written directly in terms of the applied loads on the anchor with an associated flow rule have been suggested. However, the combined loading yield surface has been defined only for a flat square or rectangular plate. None of these approaches directly account for the resistance of the relatively large anchor shank used to attach the mooring line. The results described in this paper show (1) the impact of the joint plate and shank on the size and shape of the combined loading yield surface and (2) the subsequent impact on predicting the keying behavior of SEPLAs using the plasticity approach. The influence of anchor thickness and shank height on the capacity of an idealized plane-strain anchor is first defined through two-dimensional finite-element (FE) studies. Then, the yield surface parameters for a typical plate and anchor size are provided from three-dimensional FE analysis. The keying behavior of this anchor when subjected to pullout loading from an anchor chain is simulated using the plasticity approach and the results are compared with keying paths for a simple plate anchor without a shank. The predictions using parameters derived from a plate anchor with a shank significantly outperform those using parameters derived from a plate anchor without a shank.

The Method to Calculate the Length of the Catenary for Anchored Vessel

The length of the anchor chain released directly influence the holding power of anchor and holding power of anchor decides the safety of the ship in the state of anchoring. In order to calculate the length of the catenary for anchored vessel in static hydraulic condition, Parabola and catenary mathematical model has been used in this paper to the data processing. These two kinds of thoughts are both based on the infinitesimal dividing model. The parabola method is using the Taylor series expansion to calculate the results of former 3~5 terms respectively, while catenary one uses the differential solving method. Through the example analysis to compare the accuracy of results obtained by these two methods, the conclusion can be obtained that parabola method is closely related to Taylor expansion terms. For a certain range of the anchored catenary length, the more Taylor series expansion, the more accurate results we can get; the gap of the results calculated by these two methods can be neglected. The catenary method is more accurate than that of parabolic one when the length of the catenary beyond this range.

A Kind of Floating Breakwater Sheltering Deep Water Aquaculture

This paper briefly introduces the design, construction and wave attenuation effect test of a kind of floating breakwater sheltering deep water aquaculture. This novel floating breakwater structure is composed of 28 standard modules and corresponding anchoring systems, and each standard module comprises a catamaran raft and a wave-attenuating and oscillation-inhibiting device, with a length of 30 m, a width of 7 m, a depth of 2 m and a draft of 1.1 m. Each catamaran raft employs a box-shaped multi-ribbed beam-and-slab structure, and was constructed using high-performance concrete and ferrocement materials and internally filled with polystyrene foam plastics. Each wave-attenuating and oscillation-inhibiting device uses a detachable split box-shaped structure and was pre-fabricated using high-performance concrete, with a length of 2 m, a width of 1.638 m and a height of 2 m. Each standard module is anchored using 6 anchor chains, each of which has an on-floor length of about 25 m. After construction, this floating breakwater system was tested for wave attenuation effect, and the data analysis results show that the floating breakwater system has a wave attenuation effect of up to 50 %.

Yeast cell surface display for lipase whole cell catalyst and its applications

The cell surface display technique allows for the expression of target proteins or peptides on the microbial cell surface by fusing an appropriate protein as an anchoring motif. Yeast display systems, such as Pichia pastoris, Yarowia lipolytica and Saccharomyces cerevisiae, are ideal, alternative and extensive display systems with the advantage of simple genetic manipulation and post-translational modification of expressed heterologous proteins. Engineered yeasts show high performance characteristics and variant utilizations. Herein, we comprehensively summarize the variant factors affecting lipase whole cell catalyst activity and display efficiency, including the structure and size of target proteins, screening anchor proteins, type and chain length of linkers, and the appropriate matching rules among the above-mentioned display units. Furthermore, we also address novel approaches to enhance stability and activity of recombinant lipases, such as VHb gene co-expression, multi-enzyme co-display technique, and the micro-environmental interference and self-assembly techniques. Finally, we represent the variety of applications of whole cell surface displayed lipases on yeast cells in non-aqueous phases, including synthesis of esters, PUFA enrichment, resolution of chiral drugs, organic synthesis and biofuels. We demonstrate that the lipase surface display technique is a powerful tool for functionalizing yeasts to serve as whole cell catalysts, and increasing interest is providing an impetus for broad application of this technique.

A simplified method for reliability- and integrity-based design of engineering systems and its application to offshore mooring systems

This paper presents a simplified method for the reliability- and the integrity-based optimal design of engineering systems and its application to offshore mooring systems. The design of structural systems is transitioning from the conventional methods, which are based on factors of safety, to more advanced methods, which require calculation of the failure probability of the designed system for each project. Using factors of safety to account for the uncertainties in the capacity (strength) or demands can lead to systems with different reliabilities. This is because the number and arrangement of components in each system and the correlation of their responses could be different, which could affect the system reliability. The generic factors of safety that are specified at the component level do not account for such differences. Still, using factors of safety, as a measure of system safety, is preferred by many engineers because of the simplicity in their application. The aim of this paper is to provide a simplified method for design of engineering systems that directly involves the system annual failure probability as a measure of system safety, concerning system strength limit state. In this method, using results of conventional deterministic analysis, the optimality factors for an integrity-based optimal design are used instead of generic safety factors to assure the system safety. The optimality factors, which estimate the necessary change in average component capacities, are computed especially for each component and a target system annual probability of system failure using regression models that estimate the effect of short and long term extreme events on structural response. Because in practice, it is convenient to use the return period as a measure to quantify the likelihood of extreme events, the regression model in this paper is a relationship between the component demands and the annual probability density function corresponding to every return period. This method accounts for the uncertainties in the environmental loads and structural capacities, and identifies the target mean capacity of each component for maximizing its integrity and meeting the reliability requirement. In addition, because various failure modes in a structural system can lead to different consequences (including damage costs), a method is introduced to compute optimality factors for designated failure modes. By calculating the probability of system failure, this method can be used for risk-based decision-making that considers the failure costs and consequences. The proposed method can also be used on existing structures to identify the riskiest components as part of inspection and improvement planning. The proposed method is discussed and illustrated considering offshore mooring systems. However, the method is general and applicable also to other engineering systems. In the case study of this paper, the method is first used to quantify the reliability of a mooring system, then this design is revised to meet the DNV recommended annual probability of failure and for maximizing system integrity as well as for a designated failure mode in which the anchor chains are the first components to fail in the system.

Optimal design of equivalent water depth truncated mooring system based on baton pattern simulated annealing algorithm

The highest similarity degree of static characteristics including both horizontal and vertical restoring force-displacement characteristics of total mooring system, as well as the tension-displacement characteristics of the representative single mooring line between the truncated and full depth system are obtained by annealing simulation algorithm for hybrid discrete variables (ASFHDV, in short). A “baton” optimization approach is proposed by utilizing ASFHDV. After each baton of optimization, if a few dimensional variables reach the upper or lower limit, the boundary of certain dimensional variables shall be expanded. In consideration of the experimental requirements, the length of the upper mooring line should not be smaller than 8 m, and the diameter of the anchor chain on the bottom should be larger than 0.03 m. A 100000 t turret mooring FPSO in the water depth of 304 m, with the truncated water depth being 76 m, is taken as an example of equivalent water depth truncated mooring system optimal design and calculation, and is performed to obtain the conformation parameters of the truncated mooring system. The numerical results indicate that the present truncated mooring system design is successful and effective.

Force Analysis of the Anchor Chains and the Cable in the Crane-System with a Floating Base in Regular Waves

In order to analyze the force of the anchor chains and the cable in the crane-system with a floating base, firstly the system is simplified to two-rigid-body model and the anchor chains in the system are in symmetric layout; then the motion response of the system as well as the force of the anchor chains and the cable are solved by use of discrete time transfer matrix method, lastly the time history curves of motion of the system and the force of the anchor chains and the cable are obtained. The results of numerical simulation show that the roll motion has greater influences on the system comparing with sway and heave, the amplitudes of sway and heave are small. Furthermore, the force of the anchor chains are mainly caused by the roll motion while the force caused by sway and heave are relatively small.

Comparison of Neural Network Error Measures for Simulation of Slender Marine Structures

Training of an artificial neural network (ANN) adjusts the internal weights of the network in order to minimize a predefined error measure. This error measure is given by an error function. Several different error functions are suggested in the literature. However, the far most common measure for regression is the mean square error. This paper looks into the possibility of improving the performance of neural networks by selecting or defining error functions that are tailor-made for a specific objective. A neural network trained to simulate tension forces in an anchor chain on a floating offshore platform is designed and tested. The purpose of setting up the network is to reduce calculation time in a fatigue life analysis. Therefore, the networks trained on different error functions are compared with respect to accuracy of rain flow counts of stress cycles over a number of time series simulations. It is shown that adjusting the error function to perform significantly better on a specific problem is possible. On the other hand. it is also shown that weighted error functions actually can impair the performance of an ANN.

A Newly Developed Self-Contained Inclinometer for Offshore Platform Anchor Monitoring

This paper presents the research and development of a special self-contained Inclinometer based on the requirement of offshore platform monitoring. The device records the anchors inclination completely and accurately, providing information for stress analysis of the anchor chain. Laboratory calibration, platform movement simulation experiment, and real platform testing confirmed the instrument can meet the measurement requirements. The instrument is high-precision, energy-economical, mass-storage and user-friendly. Its able to work underwater continuously for up to one year. In addition, the small size minimizes the interference caused by the carriers motion. Compared with its foreign counterparts, the new instrument is inexpensive, so its suitable for extensive multi-point measurement. Now it has been installed in LH11-1 platform in the South China Sea for measurement of anchor chain inclination. Its the first time to employ measuring device with autonomous right in offshore platform monitoring in China.

Design and Experimental Research of a New Horizontal Wave and Flow Generation Device

According to the current needs of the independent power supply to the offshore marine equipment and reefs, as well as the serious status of the world's energy crisis, environmental pollution, we design a miniaturized modular turbine marine energy generation device. With turbine which is circular evenly arranged vane typed as its wave flow capturing device,and through the spindle which fixedly mounted with the turbine, transmiting the captured energy directly to the generator which is mounted at the end of the spindle,eventually the entire device achieves single-stage transmission,and overcomes the problems such as low conversion efficiency and complicated structure in comparision with the traditional multi-stage conversion power generation device.The entire device achieves offshore running by buoys floating, anchor chain mooring and data remotely controlling .With the establishment of the program, 3D modeling and simulation,prototype production and processing, performance testing of key components and prototype flume tests,the project has got a lot grades.The device can extend to the multiple complementary power supply system with offshore wind, solar and so on,and achive integrated system to islands with low-cost power supply,desalination and sewage treatment,which has a good prospect.