bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Adaptive and Efficient Boundary Approach for Density-Based Topology Optimization
Authors: Behrou Reza , Lotfi Reza , Carstensen Josephine V. , Guest James K. 
Published: November 2019

Abstract
This paper presents an adaptive nodal boundary condition scheme to systematically enhance the computational efficiency and circumvent numerical instabilities of the finite element analysis in density-based topology optimization problems. The approach revisits the idea originally proposed by Bruns and Tortorelli to eliminate the contribution of void elements from the finite element model and extends this idea to modern projection methods to stabilize the implementation, facilitate reintroduction of material, and consider additional physics. The computational domain is discretized on a fixed finite element mesh and a threshold density is used to determine if an element is sufficiently low relative density to be “removed” from the finite element analysis. By eliminating low-density elements from the design domain, the number of free Degrees-Of-Freedom (DOFs) is reduced, thereby reducing the solution cost of the finite element equations. Perhaps more importantly, it circumvents numerical instabilities such as element distortion when considering large deformations. Unlike traditional solids-only modeling approaches, a key feature of the projection-based scheme is that the design and finite element spaces are separate, allowing the design variable sensitivities in a region to remain active (and potentially non-zero) even if the corresponding analysis elements are removed from the finite element model. This ultimately means material reintroduction is systematic and driven by the design sensitivities. The Solid Isotropic Material with Penalization (SIMP) approach is used to interpolate material properties and the Heaviside Projection Method (HPM) is used to regularize the optimization problem and facilitate material reintroduction through the gradient-based optimizer. Several benchmark examples in areas of linear and nonlinear structural mechanics are presented to demonstrate the performance of the proposed approach. The resulting optimized designs are consistent with literature and results reveal the performance and efficiency of the developed method in reducing computational costs without numerical instabilities known to be due to modeling near-void elements.
Load-Flow Based Design of Compliant Mechanisms With Embedded Soft Actuators
Authors: Patiballa Sree Kalyan , Satheeshbabu Sreeshankar , Krishnan Girish 
Published: November 2019

Abstract
Transmission members such as gears and linkages are ubiquitously used in mechatronic systems to tailor the performance of actuators. However, in most bio-inspired soft systems the actuation and transmission members are closely integrated, and sometimes indistinguishable. Embedded actuation is greatly advantageous for attaining high stroke and transferring large output forces. This paper attempts at a systematic synthesis of compliant systems with embedded contractile actuators and passive members to achieve a particular kinematic objective. The paper builds on recent understanding of a compliant mechanism topology where the constituent members can be functionally classified as load transferring transmitters and strain energy storing constraints. The functional equivalence between the transmitter members and actuators are used to replace transmitters in tension with contractile actuators, thus realizing a compliant embedded system. Once a single-input single-output compliant mechanism is designed, and its load flow behavior mapped, systematic guidelines and best practices are established for embedding actuators within the topology to increase performance without altering the kinematic behavior. Several examples, including a prototype that used soft pneumatic artificial muscles is presented to validate the synthesis framework. The initial results will form the basis for designing fully autonomous compliant systems with embedded actuators and sensors without the use of computationally expensive techniques.
A New Human Intruder Detection Scheme for Video Surveillance
Authors: Xiong Shaomin , Wu Haoyu , Hirano Toshiki 
Published: November 2019

Abstract
The demand for video surveillance has increased rapidly in recent years. Artificial intelligence (AI) algorithms are key enablers for the smart functionalities of a surveillance camera. Typical smart functionalities include human or object detection, tracking and recognition. However, many of the neural network (NN) algorithms for AI require intensive computation. At the endpoint or edge such as a home surveillance camera, the computation power is limited. The intensive computation also causes higher power consumption, which is also problematic for battery powered cameras. In this paper, we introduce a new human detection scheme that requires much less computation while the accuracy is equivalent to other existing algorithms. It obtains datasets and knowledge from a complex NN algorithm at the learning and calibration phase. These datasets are later used to train two cascading lightweight machine leaning algorithms, which will be used for further human detections. It is demonstrated that the proposed scheme can be run by the camera alone and the speed of detection is much faster than other benchmark NN algorithms.
Development of Novel Rotary Magnetic Encoder
Authors: Peng Kai-Yang , Chang Jen-Yuan (James) 
Published: November 2019

Abstract
This paper discussed the development and validation of a new rotary magnetic encoder for measurement of spindle’s axial displacements. The novelty of this work is on the design of permanent magnets as the magnetizing source to produce alternative magnetic polarities on ferromagnetic material electroplated on disk/ring-like flange that is attached to the targeted spindle shaft. Through mechatronics integration and numerical finite element parameter studies, the optimal combination of the magnetizer design parameters with consideration of the arrangement of magnetoresistive (MR) elements is reached to produce the novel encoding magnetic patterns for the axial displacement measurements. The effectiveness of the proposed method is further validated through calibrated experiments leading to the conclusion of reaching 10um accuracy performance in the measurement of the spindle’s axial elongation.
A Wearable Neck Measurement Device and Monitoring System to Improve Ergonomic Performance of Surgeons
Authors: Morris Karcher , Zhao Minghui , Lam Jenny , Jacobsen Garth , Horgan Santiago , Talke Frank E. 
Published: November 2019

Abstract
The long-term health of a surgeon is significantly affected by repetitive tasks and positions assumed during surgery. In order to evaluate neck positions throughout surgery, a novel wireless neck measurement system has been designed and developed. Extension, protraction, and rotation data of the neck are captured with accelerometers and flex sensors. Data is transmitted wirelessly and processed utilizing MATLAB. Sensor results are evaluated and compared with the goal to improve the ergonomic behavior of surgeons.
Investigation of Zinc-Silver Oxide-Thermoplastic Composite for Application in a Biofilm Retardant Urinary Catheter
Authors: Gotlib Oren , Morris Karcher , Spada Frederick E. , Alagiri Madhu , Patras Katy , Talke Frank E. 
Published: November 2019

Abstract
Catheter acquired urinary tract infection (CAUTI) is a significant problem in the medical community. Interdisciplinary teams have coordinated to address this problem, yet there is still a need for an adequate solution. In this study, we investigate an electricidal solution by adopting electrochemically active materials that can be incorporated into a urinary catheter. Zinc and silver oxide powders deposited in the form of patterned electrodes on a thermoplastic substrate are shown to illustrate electricidal properties in urine, including the ability to produce electric fields, pH increases, as well as, formation of hydrogen peroxide. The newly developed samples show promising results for killing planktonic E. coli in a controlled setting.
Frequency Domain Fatigue Analysis for a Unbonded Flexible Riser: Damage Induced by Dynamic Tension
Authors: Yuan Jiabei , Hou Yucheng , Tan Zhimin 
Published: November 2019

Abstract
Evaluation of fatigue damage of offshore flexible risers is critical in flexible riser system design. For deepwater application, irregular wave time domain approach is often adopted as the state of practice to avoid excessive conservatism due to its better representation of the stochastic offshore environment. The approach can indeed fully capture the non-linear behaviors of the system at a significant cost of computational time. For example, computational time typically takes over 3∼4 weeks for a deep water free hanging riser system with thousands of fatigue load-cases and the full 3-hour simulations. On the other hand, the same scope of simulation can be completed in frequency domain within day(s), which will enable the designer to accelerate the optimization of riser system design. This paper presents an analysis method in frequency domain for assessing the fatigue damage of tensile armour wires inside the top end fitting (EF), which is induced by dynamic tension variation and often governs the riser service life in deep water applications. A validation measurement is also implemented to ensure the accuracy and practicability of this frequency domain approach in riser system design.
Pure Collapse Behavior of Pipelines With D/t Ratio Below 10: Real Scale Experimental Tests and Numerical Studies
Authors: Vilas Bôas Ana Carolina , Jorge Gabriel , e Silva Júlio Márcio , de Souza Ana Paula F. , Solano Rafael F. 
Published: November 2019

Abstract
This work addresses pure collapse experimental tests conducted with DNVGL-450 seamless pipe samples with D/t ratio equal 7.7 and 8.6. Interesting results were achieved, showing that the pipes presented a significant plastic deformation before collapse. There is a limited amount of available technical publications addressing real scale tests with thicker pipes, D/t &lt; 20, that makes the results available quite important for the better understanding of thicker pipes. FEM was conducted and a good correlation with experimental test results were obtained. The experimental and numerical results were correlated with the DNVGL-ST-F101 pure collapse limit state equation, one of the main the rule used in the design of ultra-deep-water subsea pipelines. Conclusions and recommendations for future work based on the results achieved are presented.
A Preliminary Study on the Development of a Novel Marine Growth Cleaning Robot for Jacket Platforms
Authors: Jiang Zhe , Sun Tao , Luo Gaosheng , Wang Biao , Guo Wei 
Published: November 2019

Abstract
As the underwater structures of offshore Jacket platforms are always immersed in seawater, the marine growth, which include various forms of algae, slime, and seaweed, barnacles, mussels and other species of adhesive shellfish, will attach to steel-pipe surface and will accelerate structural corrosion and impair structural safety. Currently, routine cleaning and inspection task is undertaken by divers using cleaning jets in normally every 3∼5 years. The cleaning duration for one single platform will take up more than two months, even up to half a year, due to the constraints of weather windows and limited working hours of divers. It is a risky job for divers not only because of huge pressures that water-jets produce, but also the harsh working conditions of poor visibility, unexpected vortex and waves around platform, and etc.
Underwater robots are being developed for various applications in offshore oil industry ranging from inspection to maintenance and cleaning of submerged surfaces and constructions. This paper introduces a novel underwater robot specializing in cleaning marine growth for offshore Jackets. Since the diameter of steel-pipes varies from about 600mm to 2000mm, a self-adapted mechanism is designed. The self-adaption mechanism makes the robot travel on pipes in different directions with high mobility and clean continuous region of underwater pipes’ surface at the same time. Two key issues have been studied in this paper. The magnetic adhesion method is adopted in the robot. A sensitivity study on the distance between steel-pipes and thickness of steel pipes with the adhesion force are conducted both using finite element method and experiments. Besides, the flushing capability for various nozzles has been simulated using computational fluid dynamics method. The proposed underwater robot is needed in the inspection and maintenance of offshore Jacket platforms. Compared with traditional maintenance by divers, it is more efficient, economic and safe.
How Emulation Improves Offshore Operations
Authors: McGuire Leslie 
Published: November 2019

Abstract
Subsea 7 is supporting its offshore fleet by incorporating emulation. Virtualising the actual control system software used offshore and integrating a high resolution functional 3D “digital twin” model of its vessels and equipment. Subsea 7 can effectively test control systems under as near to live conditions as possible by also incorporating historical dynamic positioning archives of vessel sea states and other external influences such as temperatures, loads and faults into the system. Using the Subsea 7 emulation techniques means operatives can be trained on exact virtualised control system software in advance of actual construction and as a result, software faults can be highlighted, de-bugged and rectified using the emulator system. The digital twin models can also be used to facilitate efficient planning of deck operations. This paper demonstrates how technology helps improve Subsea 7’s offshore operations.
Methods, Procedures, Process: A vessel emulation room is in use for control system testing and familiarisation of construction equipment, including for instance, lay, crane or diving systems and is currently developing its library of vessel functional 3D models with full integration to the control system software. By use of physics engine feedback into the functional 3D model and control systems, projects operations can be verified.
Results, Observations, and Conclusions: It is proven using emulation from an office base, for vessels operating anywhere in the world, that Subsea 7 are able to save significant costs and time. The emulations can be re-used and expanded for the full life cycle of the equipment. Over 90% of software bugs can be ironed out prior to installation, a significant advantage for Operations.
Novel/Additive Information: This paper describes a significant step towards the digitalisation of the Subsea 7 fleet and equipment incorporating the actual control system software used to operate the equipment.
Numerical Convergence on the Hydroelasticity of a Large Containership
Authors: Lu Ye , Temarel Pandeli , Jin Qiu , Wu Yousheng , Ni Xinyun , Tian Chao 
Published: November 2019

Abstract
Nowadays, more and more 20,000 twenty-foot equivalent unit (TEU) class ultra large container ships (ULCS) have been built in service across the worldwide. It is paramount that hydroelastic specialists become paying close attention to structural responses and loads predictions due to up to a 400m length of the ships. First of all, mesh convergence by finite element analysis is necessary to determine in the numerical calculation. In this paper, based on the three-dimension linear frequency domain hydroelasticity theory, the hydrodynamic meshes convergence is discussed when modelling the hull surface of the ULCS. Ascribe to the Sunway TaihuLight, rank 3 in the current TOP500 supercomputer list, the Message Passing Interface and the multi-level parallel programming model are used aimed to the wetted panels, the wave frequencies and so on. Several sets of different global grid density and grid distribution along the ship’s length for the containership are calculated to compare the hydrodynamic coefficients such as added mass, damping, wave exciting force, ship motions and exterior loads with several typical service speeds in the head regular wave. It has been concluded that sensitivity of numerical modelling converges to a stable state with increasing the panel numbers per ship. Therefore, one set of grid division optimised, and superposed elastic modes numbers are recommended in the hydroelastic analysis of numerical hydroelastic prediction of springing and whipping.
Long-Term Extreme Response of a Straight Floating Bridge Across the Bjørnafjord
Authors: Giske Finn-Idar Grøtta , Fredriksen Arnt 
Published: November 2019

Abstract
In this paper, long-term extreme response analysis is performed for a straight floating bridge across the Bjørnafjord, using a recently developed inverse first-order reliability method (IFORM) approach. Full integration of the long-term extreme response formulation is also performed for comparison. Two different environmental models are estimated based on a scatter diagram of significant wave height and peak period for the given location. The IFORM method is seen to provide reasonable estimates of the long-term extreme response, at a significantly reduced computational effort.
Studies Toward the Development of Accurate Directional Spectrum Estimation Method Using Field Observation Data
Authors: Hashimoto Noriaki , Mitsui Masao , Kawaguchi Koji , Fujiki Takashi 
Published: November 2019

Abstract
An upgraded submerged Doppler-type directional Wave Meter (DWM) can measure 31 wave quantities related to directional wave motions, i.e., water surface elevation, 3 components of water particle velocities at each layer of 10 different water depths ranging from shallow to deep. In this study, accuracy of directional spectrum estimation is investigated for various cases where directional spectra are estimated with various sets of different number of wave quantities measured with DWM. As a result, accuracy improvement is confirmed in some wave conditions when more quantities are applied to the estimations, compared with the cases where a few wave quantities are applied to the estimations. On the other hand, it was found that when the directional spectra are estimated by adding the water particle velocity components at the deep water depths, the energy concentration of the direction function tends to be estimated higher in proportion to the number of observation layers of the deeper water particle velocity components. Since this feature should be clarified in investigating characteristics of directional spectra observed with DWM, we will continue further investigation for more accurate and reliable directional spectrum estimation.
Two-Dimensional Numerical Simulation of Vortex Shedding of Multiple Stranded Ropes
Authors: Wang Xinxin , Huang Liuyi , Tang Yanli , Zhao Fenfang , Sun Peng 
Published: November 2019

Abstract
The stranded rope is one of the important components of the fishery aquaculture equipment. We investigate the fluid flow through two-dimensional stranded rope by direct simulation of the Navier-Stokes equations. We show that for different kinds of stranded rope structures, there are significant differences in hydrodynamic performance. This paper established a numerical model of unsteady flow past the stranded rope based on the Navier-Stokes equation and Morison formulas to study the hydrodynamic characteristics of three-stranded rope, four-stranded rope, and seven-stranded rope, respectively. The turbulence flow was simulated using Standard k-ε model and Shear-Stress Transport k-ω (SST) model. The flow distribution strongly depends on the Reynolds number, a range of 3,900 and 30,000. With increasing Reynolds number, the alternate eddy formation and shedding were repeated behind the stranded ropes. Such parameters of hydrodynamic characteristics of multiple stranded ropes were calculated as the lift and drag coefficients, and vortex shedding frequencies. The numerical simulation results presented flow performances of different cross sections (a, b, c, d) at different Reynolds numbers. However, Reynolds number has no significant impact on the Strouhal number for the same attack angle of the stranded rope.
Numerical and Experimental Research on Residual Ultimate Strength of Hull Plates Under Uniaxial Cyclic Loads
Authors: Xia Tian , Yang Ping , Cui Cong , Peng Ziya , Ma Li 
Published: November 2019

Abstract
The present paper aims at obtaining insights on the strength behaviors of ship hull plates under uniaxial cyclic loads. The residual ultimate strength of ship hull plates under uniaxial cyclic load is studied by numerical analysis using nonlinear finite element method. A series of tests are also conducted for comparison and verify the reasonability of numerical results. The accumulated plastic damage and crack propagation from the low cycle fatigue damage during cyclic load are both considered in present study. From the numerical results and tests some significant conclusions are drawn to the residual ultimate strength of plates under uniaxial cyclic loads.
Cuttings Transport Simulation in Large-Diameter Inclined Borehole
Authors: Ignatenko Yaroslav , Gavrilov Andrey , Bocharov Oleg , May Roland 
Published: November 2019

Abstract
An Eulerian mixture model of the two-phase flow was used for cuttings transport simulation. The model was tested using experimental data for particles transport in pipes. Three types of problem statements were analyzed: steady-state flow, non-stationary flow in a short-length channel with periodic boundary conditions, and non-stationary flow in a long channel.
Simulation of cuttings transport by Herschel-Bulkley fluid through an inclined 21-inch borehole/–6.5-inch drillpipe annulus was performed. All problem statements showed very close results, even for unsteady flow. These results demonstrated the applicability of 2D steady-state problem formulation for cuttings transport simulation.
The unsteady flow was observed for an inclination of less than 20 degrees. Slow downward sliding of cuttings in the lower part of inclined boreholes was observed simultaneously with upstream dunes movement. Drill pipe rotation significantly decreased the cuttings concentration and pressure gradient, and shifted the maximum cuttings transport downward sliding rate from a 20- to 40-degree inclination.
Numerical Simulation for Predicting Ship Resistance and Vertical Motions in Regular Head Waves
Authors: Bekhit Adham S. , Lungu Adrian 
Published: November 2019

Abstract
The present study is concerned with predicting the resistance and vertical motions of the surface combatant DTMB5512 ship model in regular head waves. A series of numerical simulations are performed for various wave lengths, heights and different ship speeds. Computations are performed by making use of the ISIS-CFD solver of the commercial software Fine™/Marine provided by NUMECA, where the discretization in space is based on finite volume method using unstructured grid. The unsteady Reynolds-Averaged Navier-Stokes equations are numerically solved while the turbulence is modeled by making use of the k-ω SST model. The free-surface is captured through an air-water interface based on the Volume of Fluid (VOF) method. Computed results are validated through direct comparisons with the experimental data provided by IIHR test cases. For the sake of numerical results verification, a grid convergence study is performed on four computational grids and a time step convergence test is also included. Validation of the numerical results shows a reasonable agreement with the experimental data.