bluuebunny/crossref_metadata_2025 huggingface dataset:
A Lubrication Model of Elliptical Point Contact for Spiral Bevel Gears With Asymmetric Varying Velocity
Authors: Gopalakrishnan Srikumar C. , Lim Teik C. , Wang Yawen
Published: November 2019

In this work, elliptical contact is modeled in spiral bevel gear with a suitable ellipticity ratio. The elliptical point contact is modeled using constant velocity and varying velocity with side leakage. A loaded tooth contact analysis was carried out to determine the kinematic and gear mesh force developed during one mesh cycle. The kinematic parameters of the meshing gear pair, namely the contact cells, rolling velocity, sliding velocity and the load distribution in one mesh cycle are used in the elliptical point contact calculation to calculate the pressure and film thickness distribution. The effect of elliptical point contact and varying velocity on the pressure and film thickness distribution are studied. The time-varying contact parameters which are obtained from the tooth contact analysis are used in the tribological calculations. The effect of shaft misalignments on the elastohydrodynamic pressure distribution is also studied in this work.
A Systematic Rapid Creative Design Framework for Complex Mechanical Systems From Conceptual Design to 3D Virtual Simulation
Authors: Yu-Tong Li , Yu-Xin Wang
Published: November 2019

This paper presents a systematic rapid creative design framework for complex mechanisms to support creative conceptual design schemes’ generation and 3D virtual simulation. In conceptual design stage, a rule-based creative conceptual design system is constructed to expand conceptual design solution space through operating design rules related to functional requirements of design problems with graphic carriers. Compared with FBS models or catalogue-based matching approaches, the rule-based system can dig out more innovative conceptual design schemes including generalized mechanisms. Then a great number of conceptual design schemes generated in conceptual design are represented with symbolic schemes and identified into constituent basic mechanisms and their connections. To the constituent basic mechanisms, the object-oriented (OO) technology is applied to set up their 3D virtual solid models with encapsulated key feature parameters, which can be automatically modified by system’s database with the aid of the new defined classes. According to the OO solid models of constituent basic mechanisms and their connections, a 3D space layout algorithm considering the connections among the solid models is developed to determine the position of each constituent solid basic mechanism. Finally, an object-oriented based kinematic analysis method is pro-posed to carry out automatic kinematic analysis of the complex mechanisms related to the symbolic schemes. By means of the virtual-assembly approach and the kinematic data, all constituent components in the complex mechanisms are put onto the proper positions as they are assembled manually. In this way, the systematic design processes for complex mechanisms from creative conceptual design schemes’ generation, to 3D virtual solid design, layout de-sign, kinematic analysis, and virtual assembly and simulation are realized automatically. Based on the framework presented in this paper, rapid generating and evaluating innovative, excellent-performance schemes of complex mechanisms in 3D virtual prototype form are possible.
Control Strategy for Vehicle Lateral Dynamics Combining Torque Vectoring With Four Wheel Steering
Authors: Vignati Michele , Bravin Mauro , Sabbioni Edoardo
Published: November 2019

This paper presents a control strategy for multi-actuated vehicle for controlling the vehicle lateral dynamics. The controller tries to couple torque vectoring control, which is possible thanks to independent electric motors, with four wheels steering system by analyzing the vehicle behavior in the phase plane. A performance index is then defined to weight the two actuators intervention. The controller is tested in simulation environment where several typical maneuvers were simulated.
Performance Comparison of Inertial Measurement Units Fused With Odometry in Extended Kalman Filter for Dead-Reckoning Navigation
Authors: Carey Kevin , Abruzzo Benjamin , Harvie David P. , Korpela Christopher
Published: November 2019

This paper aims to aid robot and autonomous vehicle designers by providing a comparison between four different inertial measurement units (IMUs) which could be used to aid in vehicle navigation in a GPS-denied or inertial-only scenario. A differential-drive ground vehicle was designed to carry the multiple different IMUs, mounted coaxially, to enable direct comparison of performance in a planar environment. The experiments focused on the growth of pose error of the ground vehicle originating from the odometry senors and the IMUs. An extended Kalman Filter was developed to fuse the odometry and inertial measurements for this comparison. The four specific IMUs evaluated were: CNS 5000, Xsens 300, Microstrain GX5-35, and Phidgets 1044 and the ground truth for experiments was provided by an Optitrack motion capture system (MCS). Finally, metrics for choosing IMUs, merging cost and performance considerations, are proposed and discussed. While the CNS 5000 has the best objective error specifications, based on these metrics the Xsens 300 exhibits the best absolute performance while the Phidgets 1044 provides the best performance-per-dollar.
Computational Creativity via Assisted Variational Synthesis of Mechanisms Using Deep Generative Models
Authors: Deshpande Shrinath , Purwar Anurag
Published: November 2019

Computational methods for kinematic synthesis of mechanisms for motion generation problems require input in the form of precision positions. Given the highly non-linear nature of the problem, solutions to these methods are overly sensitive to the input — a small perturbation to even a single position of a given motion can change the topology and dimensions of the synthesized mechanisms drastically. Thus, the synthesis becomes a blind iterative process of maneuvering precision positions in the hope of finding good solutions. In this paper, we present a deep-learning based framework which manages the uncertain user input and provides the user with a higher level control of the design process. The framework also imputes the input with missing information required by the computational algorithms. The approach starts by learning the probability distribution of possible linkage parameters with a deep generative modeling technique, called Variational Auto Encoder (VAE). This facilitates capturing salient features of the user input and relating them with possible linkage parameters. Then, input samples resembling the inferred salient features are generated and fed to the computational methods of kinematic synthesis. The framework post-processes the solutions and presents the concepts to the user along with a handle to visualize the variants of each concept. We define this approach as Variational Synthesis of Mechanisms. In addition, we also present an alternate End-to-End deep neural network architecture for Variational Synthesis of linkages. This End-to-End architecture is a Conditional-VAE (C-VAE), which approximates the conditional distribution of linkage parameters with respect to coupler trajectory distribution. The outcome is a probability distribution of kinematic linkages for an unknown coupler path or motion. This framework functions as a bridge between the current state of the art theoretical and computational kinematic methods and machine learning to enable designers to create practical mechanism design solutions.
Prediction of Design Team Performance on a Conceptual Design Task Using an Automatable, Topic-Independent Analysis of Language Use
Authors: Cannon David M. , Edelman Jonathan
Published: November 2019

In this research, starting with an established metric called the Language Style Matching (LSM) measure [1] we show that some new LSM-based measures can predict team performance on an open-ended design task. We call these Style Entrainment Signal (SES) measures. Using them, two conversational patterns are newly identified, which we call “dwelling” and “forward-moving.” We show that a forward-moving pattern is associated with better-rated results produced by teams in 30-minute long conceptual design meetings with significant brainstorming activity. Through this, we gain insight into some of the interpersonal dynamics that contribute to a design team’s success. These results are founded on previous work in psycholinguistics, where it has been shown that analysis of language use can be used in several ways to predict a team’s performance on short, well-defined tasks. By expanding the research to more open-ended design tasks, and identifying two newly-measurable conversational patterns, we contribute back to psycholinguistic theory. The analysis developed for this work is automatable and topic-independent, and so it has potential to be applied widely.
Design of Non-Periodic Lattice Structures by Allocating Pre-Optimized Building Blocks
Authors: Choi Haejoon , Chung Baek Adrian Matias , Kim Namhum
Published: November 2019

The development of lattice design approaches using topology optimization to create complex lattice structures is the focus of ongoing research as the lattice structures show great potential throughout a wider range of research fields. Unfortunately, many of the methods suggested are often very difficult to industrialize due to their complexity and excessive computational costs in the design process. This paper proposes a novel framework of generating non-periodic lattice structures using topologically pre-optimized building blocks to improve the computational efficiency of the optimization process while maintaining the performance of the target structure and to make the process of obtaining optimal design more accessible for people with limited knowledge of topology optimization. The proposed method is comprised of two phases: the generation of a library holding optimized building blocks that can endure various loading conditions and the allocation of these building blocks at the proper location in the design space based on stress information obtained from the finite element analysis. Numerical examples are presented to show that the method is feasible and able to achieve reasonable performances, demonstrating its efficacy.
Synthesizing Mechanical Chains for Morphing Between Spatial Curves
Authors: Li Yucheng , Murray Andrew P. , Myszka David H.
Published: November 2019

This work investigates the kinematic synthesis methodology for designing a chain of three-dimensional bodies to match a set of arbitrary spatial curves. The bodies synthesized can be one of three types: a rigid segment, a helical segment with constant curvature and torsion but varying length, and a growth segment that maintains its geometry but may be scaled to become larger or smaller. To realize mechanical chains, only rigid and helical segments are used. After designing the segments, they may be aligned with the original spatial curves with their ends connected via an optimization. For two curves, these connections may be made with revolute joints to obtain high accuracy. For three or more curves, spherical joint connections allow for the best accuracy. To compare curves as is useful in morphometry, all three segment types may be employed. In this case, an accurate description of the changes between curves is important, and optimizing to connect the segments is not needed. The procedure for redefining the curves in a way that the techniques in this paper may be applied, as well as the methodologies for synthesizing the three segment types are presented. Examples include a continuum robot problem and the morphometric analyses of chochlear curves and the lambdoidal suture. This work extends the established planar techniques for synthesizing mechanisms and addressing morphometric issues that are motivated with curves in two-dimensions.
Field Test and Characteristic Analysis of Railroad Track Vibration Energy Harvester
Authors: Zuo Jianyong , Yu Jie , Liu Cheng , Gu Yihao , Zuo Lei , Pan Yu , Lin Teng
Published: November 2019

Railroad vibration energy harvester has been researched and developed to harness the energy from the vibration of railway track when the trains pass. The vibrational energy could be transformed into electrical energy using mechanical motion rectification (MMR) mechanism and then further be used to power trackside equipment including sensors and some smart electrical devices. In order to test the performance of the MMR railroad energy harvesting system, a series of infield tests were conducted with a self-developed distributed measurement system in Railroad Test Lab at Tongji University. A 10V peak voltage was achieved with 8 Ohms external resistive load at the train speed of 30 km/h, which was consistent with the result of in-lab bench tests. In addition, some experience of design and installation for the motioned based energy harvesting system was gained, which can provide some references for the future improvement of railroad energy harvesting systems.
Informing Design Defixation Using Interventions for Psychiatric Disorders
Authors: Pedret K. , Shu L. H.
Published: November 2019

Design fixation has been extensively studied in the context of engineering design, leading to several interventions to reduce its negative effects. The concept of mental fixation has roots in diverse psychological contexts from Freudian psychoanalysis to Gestaltism and eating disorders. Although the underlying concepts are similar, the phenomenon has different names, including mental set, rumination, functional fixedness, obsession, etc. Mental fixation in its various forms is always a barrier to problem solving, whether the problem is a psychological disorder or an engineering-design task.

The present paper explores the applicability to design fixation of cognitive therapy, a form of psychotherapy that relies on questioning to identify and modify inaccurate perceptions. Originally developed to treat depression, it is now used to treat a variety of psychiatric disorders. Specific interventions used in cognitive therapy are described in detail towards developing new means of overcoming design fixation. These interventions include cognitive restructuring and exposure response prevention. Also explored are links to other research results from psychology and cognitive science, including focused distraction, and the effects of music and physical exercise. In addition to developing new interventions, existing design-fixation interventions can also be supplemented using insights from these research results.
A Lie Group Approach to the Modular Modeling of Kinematically Non-Redundant Parallel Mechanisms
Authors: Müller Andreas
Published: November 2019

Parallel kinematics manupulators (PKM) are established robotic systems. Yet there is no established modeling approach that takes into account the special kinematics of the (usually structurally identical) limbs. In this paper a modeling approach is proposed that accounts for the special kinematics and topology of PKM. It makes use of modern Lie group formulations for rigid body systems that admits efficient description independent of modeling conventions. A task space formulation is presented that can be directly used for model-based control purposes.
Development of an Assist-As-Need Controller for an Upper-Limb Exoskeleton With Voluntary Torque Estimate
Authors: Chatfield Logan T. , Fortune Benjamin C. , McKenzie Lachlan R. , Pretty Christopher G.
Published: November 2019

This study considers the development of an assist-as-need torque controller for an exoskeleton for stroke rehabilitation. Studies have shown that active patient participation improves the patient’s recovery from stroke. Assist-as-need control, providing the patient with the assistance they need to complete a task, is desirable, as the assistance can be varied to maximise patient participation. However, research is limited, and current methods cannot guarantee optimal assistance as non-zero assistive forces are still provided to subjects that are capable of completing the task unassisted. This study proposes a control system to vary and optimise the assistance for a subject based on their capabilities. A particle filter developed from previous research is used to estimate the subject’s voluntary effort. The assistive torque is determined from a target torque and the voluntary effort. The controller is shown to be effective, as zero assistance is provided to a subject capable of completing the task unassisted. Additionally, the assistance will increase if the subject fatigues. Using the estimate of the subject’s strength, the assistive torque can be accurately set to maximise a patient’s participation, and therefore, the assist-as-need controller can lead to improved therapeutic results.
Frequency Response Analysis of Macro-Micro Stages With Active Disturbance Reject Controller
Authors: Zeng Danping , Huang Ruirui , Yang Zhijun , Xue Wenchao
Published: November 2019

Under the disturbance of friction and the elastic deformation of motion stage, the positioning accuracy of traditional mechanical bearing high speed direct-drive motion stage can only reach the micron level, which is difficult to meet the requirement of higher speed precision positioning. Therefore, the macro-micro stages utilize the flexure hinges to compensate for displacement in the friction dead zone. However, due to the nonlinear elastic vibration of the flexure hinge during the action, the settling time of micro-platform is different with stiffnesses. Effect analysis of different stiffness on the settling time of the micro-platform is significant for the platform design. According to the motion characteristics of the macro-micro stages, this paper designs the cascade extended state observer (ESO) to estimate and compensate for the disturbance and combine the proportional–derivative (PD) controller as the active disturbance rejection control (ADRC) strategy of the micro-platform position loop. Through the frequency response analysis of the control system, the influence of different stiffness on the settling time of micro-platform is explored. The simulation results show that the ADRC strategy based on cascade ESO has better robustness, and the macro-micro stages have a shorter settling time when the flexure hinge have smaller stiffness during the positioning phase.
Developing an Interview Protocol for an Engineering Capstone Design Course
Authors: Clark McKenzie , Shah Devanshi , Kames Elisabeth , Morkos Beshoy
Published: November 2019

In a multifaceted course such as senior capstone design, it is integral to ensure students are receiving a value adding experience. In most universities across the United States, senior capstone design is a multiple semester sequence where design is heavily emphasized and students are encouraged to test their skills, both technical and nontechnical, by solving and implementing solutions to real industry problems. Given the nature of design courses, the takeaways are not things that can be measured solely through the use of a letter grade. Rather, an in-depth reflective interview must be performed to fully comprehend what students received from the course. In this study, an In-Depth Interview Protocol was developed to understand the effectiveness of engineering design courses and improve design education as a whole.

This paper outlines the phases that contribute towards the development of an effective interview protocol for implementation in senior capstone design curriculum. The formulation and considerations are outlined with respect to design curriculum and student success. This protocol will be utilized to perform a Reflection Interview for each senior design project team at the end of the spring 2019 semester. The assignment is not graded and is inquisitive on the students’ perceptions of motivation during their time at Florida Tech. The qualitative data gathered will be eligible for further studies and analysis.
Agent-Based Modeling of Decisions and Developer Actions in Wind Farm Landowner Contract Acceptance
Authors: Syal Sita M. , Ding Yiqing , MacDonald Erin F.
Published: November 2019

This paper presents an agent-based model to investigate interactions between wind farm developers and landowners. Wind farms require hundreds of square miles of land for development and developers typically interact with landowners to lease land for construction and operations. Landowners sign land lease contracts without knowing the turbine layout, which affects aesthetics of property as well as value of the lease contract. Having a turbine placed on one’s land is much more lucrative than not, but landowners have to sign over the use of their land without knowing if they will receive this financial benefit or not. The timing of this process, typically referred to as “Landowner Acquisition,” introduces high uncertainty for both stakeholders and represents a major pain point of the industry — a source stated up to 50% of wind projects fail due to landowner acquisition issues. We present an agent-based model that models the land lease contract period with unique decision-making characteristics for a set of landowners and a wind farm developer. Citizen participation is an integral part of community acceptance of wind farms, thus we use principles from past studies to quantify three actions a developer can take to influence landowner decisions: (1) community engagement meetings; (2) preliminary environmental studies; and (3) sharing the wind turbine layout with the landowner. The results show how landowner acceptance rates can potentially change over time based on what actions the developer takes. Overall, developers can use this model to better understand interactions with landowners and determine what actions may help positively influence landowner acceptance rates.
A Strategy for Adaptive Sampling of Multi-Fidelity Gaussian Processes to Reduce Predictive Uncertainty
Authors: Ghosh Sayan , Kristensen Jesper , Zhang Yiming , Subber Waad , Wang Liping
Published: November 2019

Multi-fidelity Gaussian process (GP) modeling is a common approach to employ in resource-expensive computationally demanding algorithms such as optimization, calibration and uncertainty quantification where multiple datasets of varying fidelities are encountered. Briefly, in its simplest form, a multi-fidelity GP is trained on two separate sources of datasets each with its own fidelity level, e.g., a software code/simulator for the low-fidelity source and real-world experiments for the high-fidelity source. Adaptive sampling for multi-fidelity Gaussian processes is a challenging task since we not only seek to estimate the next sampling location of the design variable, but also account for the data fidelities. This issue is often addressed by including the cost of the data sources as an another element in the search criterion in conjunction with an uncertainty reduction metric. In this work, we extent the traditional design of experiment framework for multi-fidelity GPs by partitioning the prediction uncertainty based on the fidelity level and the associated cost of execution. In addition, we utilize the concept of a meta-model believer which quantifies the effect of adding an exploratory design point on the GP uncertainty prediction. We demonstrate the framework using academic examples as well as an industrial application of a steady-state thermodynamic operation point of a fluidized bed process.
Direct Solid Element Slicing in Topology Optimization for Additive Manufacturing
Authors: Bender Dylan , Barari Ahmad
Published: November 2019

The traditional input to almost all commercially available Additive Manufacturing (AM) systems is in STL (Standard Tessellation Language) format, which represents a solid model by its tessellated surfaces. This does not allow transferring the entire information of a solid model to the additive manufacturing preprocessing system. However, in some recent applications such as additive manufacturing preprocessing simulation, closed-loop of topology optimization and additive manufacturing process planning, and AM-based design optimization the full access to the solid model information is necessary. Slicing of the finite element model directly is introduced in this paper. The presented approach enables access to the entire solid model information during the AM preprocessing tasks with a focus on coupling the topology optimization in the design process with the actual manufacturing constraints.
Computational Cognition for Mission Command and Control Decisions Facing Risk in Unknown Environments
Authors: Short Ada-Rhodes , DuPont Bryony L.
Published: November 2019

Systems operating in hazardous and remote environments is both desirable from a scientific perspective and incredibly difficult from an engineering and logistical perspective. This paper develops a novel two-system top-down computational-cognition-based agent and investigates its ability to respond to unanticipated situations in a hazardous environment. A simulated space mission is performed in which a Martian settlement site is constructed by a team of robots. In order to evaluate the agent’s ability to respond to unanticipated mission scenarios, “black swan” events are added to the simulation. We found that the agent was able to respond well to black swan events that changed the mission conditions in a detectable way, but black swans that were either undetectable or gave the agent inaccurate mission information increased the likelihood of failure. This work presents an interesting first step towards autonomous systems that are more resilient when facing hazardous or unknown environments. Additionally, the techniques presented here can handle large, complex problems with very minimal computational resources.
Key Issues on Flextensional Piezoelectric Energy Harvester Developments
Authors: Xu Tian-Bing , Zuo Lei
Published: November 2019

A “33” mode (mechanical stress being in parallel to the electric dipole moment direction) piezoelectric lead zirconate titanate (PZT) multilayer stack-based piezoelectric flextensional energy harvester (PZT-Stacked-FEH) has been developed. Interdisciplinary approaches had been taken to increase the performance of the PZT-Stacked-FEH. First, an elastic flextensional frame for force amplification has been optimally designed to capture more mechanical energy with high energy transition efficiency into the PZT-Stacked-FEH. Second, a “33” mode piezoelectric PZT multilayer stack (PZT-Stack) was employed instead of “31” mode (stress being in perpendicular to the dipole moment direction) single layer piezoelectric component to increase mechanical to electrical energy conversion efficiency and to generate more electrical charges in order to improve energy storage efficiency. With these approaches, the PZT-Stacked-FEH demonstrates excellent performance: 1) a 19% of overall mechanical to electrical energy conversion efficiency was achieved, 2) 48.6 times more mechanical energy was transited into PZT-Stacked-FEH and 26.5 times more electrical power was generated than directly applying force to the PZT-stack, and 3) energy storage efficiency was significantly improved. In this paper, we are focusing on the investigations for the off-resonance mode performance of the PZT-Stacked-FEH through theoretical modeling, prototype development, and experimental studies. A prototype PZT-Stacked-FEH of weight 18 grams was able to generate 666 mW electrical power under 52 Nrms force at 250 Hz, which is much lower than the resonant frequency (936 Hz). At this condition, a 6,600 μF super-capacitor was charged from 0 to 7 V in 1.6 second, at an average rate of 100 mW. Furthermore, 70% of generated appear electrical powers were delivered to matched resistive loads in the investigated regime of frequencies. Finally, the experimental results matched well with theoretical predictions which verified the developed theoretical models.
Deposition of Highly Transparent and Conductive Films on Tilted Substrates by Atmospheric Pressure Plasma Jet
Authors: Chen Yu-Chen , Chen Wen-Kai , Huang Jing-Chi , Juang Jia-Yang
Published: November 2019

We study the influence of the substrate tilt angle on the microstructure and optoelectronic properties of gallium-doped zinc oxide (GZO) thin films deposited by the atmosphere pressure plasma jet (APPJ) method. The nozzle trajectories play a key role in oblique angle deposition. In the process of oblique angle deposition, if the nozzle scanned from the upstream side to the downstream side, the electrical properties such as resistivity, carrier concentration and mobility deteriorate considerably. The optical properties also worsen — specular transmittance goes down and diffuse transmittance increase to a significant amount. This degradation can be attributed to the “pre-deposition” of the GZO adsorbed particles (ad-particles) on the downstream side of the raw glass where the nozzle has not scanned. These GZO ad-particles serve as nuclei on which the incoming vapor particles deposit preferentially. Scanning electron microscopy (SEM), and grazing incidence X-ray diffraction (GIXRD confirmed that the film near the downstream is thicker, less smooth, and porous than that near the upstream. The undesirable situation can be mitigated or even completely removed via proper nozzle scanning trajectories — reversing the scanning trajectory of the nozzle. If the nozzle scans from the downstream side to the upstream side, no pre-deposition of the GZO ad-particles to deteriorate the film properties and therefore the obliquely deposited films perform as well as the films deposited without tilt, i.e. flat substrate. This work presents a solution to the challenge of depositing TCO on tilted and curved surfaces.
Platform Design for Characterizing Shear Force Produced by Magnetized Magnetorheological Fluid
Authors: Lee Ping-Hsun , Chang Jen-Yuan (James)
Published: November 2019

In this paper we proposed a platform for measuring shear force of magnetorheological (MR) fluid by which the relationship of yield stress and magnetic flux density of specific material can be determined. The device consisted of a rotatable center tube in a frame body and the magnetic field was provided by two blocks of permanent magnets placed oppositely outside the frame body. The magnitude and direction of the magnetic field were manipulated by changing the distance of the two permanent magnets from the frame body and rotating the center tube, respectively. For determining the magnetic field of the device, we adopted an effective method by fitting the FEM (finite element method) result to the measured one and then rebuilt the absent components to approximate the magnetic field, which was hardly to be measured simultaneously as different device setup were required. With the proposed platform and analytical methods, the drawing shear force and the corresponding yield stress contributed by MR fluid could be evaluated in respect to the magnitude and direction of given magnetic flux density with acceptable accuracy for specific designing purposes without a large, complex, and expensive instrument.
Development of a Portable Reader for an Optical Intraocular Pressure Sensor
Authors: Truong Phuong , Phan Alex , Williams Nicolas , Talke Frank E.
Published: November 2019

This paper presents various designs of a handheld reader for an interferometric intraocular pressure measurement system. Reflected lights from the implanted sensor form interference fringes which can be captured using a camera. Image processing software was used to analyze the fringe pattern and determine the eye pressure. Various light sources were considered and the LED with a laser line filter was selected for its ability to generate quality fringe patterns and portability. Three generations of handheld readers have been developed and tested. Interference patterns acquired from each reader were compared to assess the limiting and promising features related to measurement time, form factor, working distance, ease of use, and quality of fringes. Results show that the DSLR-based reader has the highest quality images with the largest form factor while the smartphone-based reader offers the smallest form factor with ease of use and accessibility for the patient.
Application of Code Division Multiple Access Technology in Readout Circuit and System Design for an Ultra-Thin On-Cell Flexible Capacitive Touch Panel
Authors: Lin Ying-Jia , Su Ying-Cheng , Chao Paul C.-P. , Zhang Jia-Yu , Pribadi Eka Fitrah
Published: November 2019

A capacitive sensing circuit including electrodes for a 7-inch ultra-thin flexible on-cell touch panel has been designed. Implementing code-division multiple sensing (CDMS) with Walsh transform to scan Tx electrodes is chosen to improve the signal-to-noise ratio (SNR). The algorithm applies to field programmable logic array (FPGA). The sensing readout algorithm is applied to work on 4 Tx transmitter electrodes and 4 Rx sensing electrodes. The switched-capacitor (SC) circuit is applied to avoid disturbing sample signal from parasitic capacitance and enlarge the voltage difference from capacitance changes of the touch panel. 12-bit ADC to transfer the front-end analog signal to digital code. The digital part adopts a correction algorithm to eliminate the background value of the panel, the moving average algorithm has an adjustable signal-to-noise ratio function, and the Walsh conversion demodulation algorithm improves the touch report rate to achieve high SNR with up-to 34 dB.
Behaviour of a Suspended Wellbay Module and Flare Tower in Waves During Transit to Shore
Authors: Chan Hoi-Sang , Armaoğlu Evren , Thomson Matthew , Garner Alistair
Published: November 2019

The extended lift operation to deliver the Wellbay module (M5) combined with the Flare Tower (M8) from the Miller Platform in the North Sea to the shore using the Semi-Submersible Crane Vessel S7000 was restricted by the clearances between M5/M8 and the vessel crane booms. A method to calculate the clearances of the M5/M8 normal to the vessel crane booms has been developed and used in a frequency-domain response analysis to define operability limits. Investigations based on a series of scale model tests in regular waves and irregular short-crested waves including motion decay tests in calm water, conducted by the Maritime Research Institute (MARIN) in the Netherlands, were also made to further evaluate the behaviour of the suspended M5/M8 on S7000’s main hooks during transit. The time series of decay motions of the suspended M5/M8 obtained from the decay motion tests and a time domain analysis are compared and used to derive rigging damping. The numerical results of the frequency-domain analysis are validated with the experimental data for response amplitude operators (RAOs) found in regular waves and pink noise waves, significant and 3 hour most probable maximum/minimum (MPM) responses of interest in irregular waves.
Thorough Verification and Validation of CFD Prediction of FPSO Wind Load for Confident Applications
Authors: Xu Wei , Huang Zhenjia (Jerry) , Kim Hyunjoe
Published: November 2019

This paper presents our verification work on CFD modeling practice for the prediction of FPSO wind loads. The modeling practice was developed from the TESK CFD JDP [1]. In the verification, the measured data from a benchmark model test were used to check CFD simulation results. The exact physical model of the model test was used in the numerical modeling (model-of-the-model). To establish high confidence in the CFD modeling and simulations, the modeling practice was thoroughly verified, which covered the following critical elements: mesh resolution, domain size, outlet boundary condition, turbulence model, Reynolds effect, wind profile, prism layer effect on total wind forces, effects of the gap between wind tunnel floor and model bottom, blockage effect due to tunnel side walls and ceiling, and effects of geometry details (small size pipes). The verification results show that CFD can be used as an alternative tool for predicting wind loads and moments on a FPSO for engineering purposes following the modeling practice, and careful QA and QC.
Section Translational Movement Imposition for Macroelements
Authors: Provasi Rodrigo , de Arruda Martins Clóvis
Published: November 2019

Boundary conditions play a very important role in any mathematical model. They heavily influence the response near the region they are, but the farther the interest region is, the less important the boundary condition influence becomes. Also, the response depends of which movements are constrained or imposed and which are not. This influence can be seen in all type of problems, ranging from simple beams to complicated structures.

For tubular structures, such as flexible pipes and umbilical cables, the boundary conditions are usually given in terms of imposed movements in sections, which are commonly assumed, by hypothesis, as rigid bodies. To deal with this type of structures, the authors presented in previous works the macroelements. They are finite elements that incorporate geometrical characteristics in the formulation, leading to well behaved contact models with a smaller number of degrees of freedom.

One major feature of the model is the orthotropic cylindrical layer that uses Fourier series for the displacements. This led to specific contact models and bring the difficulty in the representation of boundary conditions in terminal sections, since different nature displacements (one the aforementioned Fourier and other one standard description) must be dealt with.

This paper address how to impose translational movement for sections using macroelements. All the description of how the coupling is made and the constraint enforcement done by using a penalty-based formulation. This work also highlights the implementation, finalizing with comparison with a conventional finite element program.
Application for Improved Awareness of Cable Geometry During Seismic Survey Operation
Authors: Grindheim Jan Vidar , Welker Ken E. , Revhaug Inge
Published: November 2019

Seismic surveys for petroleum exploration employ a number of towed cable streamers of lengths in the order of 3∼12 km. Accurate positioning is important both for navigation and control of the streamer spread and for seismic data processing. In the present study, a numerical streamer model based on a Finite Element Method is implemented both as an Extended Kalman filter and an Ensemble Kalman filter. The streamer model includes features such as tailbuoy, locally estimated sea current introduced at each node, control bird inputs, cable stretch and tension. The filter implementations are intended to blend the streamer model with observations such as acoustic range measurements and satellite navigation positioning. The implementations have been compared and validated employing full scale data for two line changes. The purpose is to investigate the filters’ performance during periods with poor or missing observations.
Path Following and Collision Avoidance of Underactuated Marine Vessels Based on MPC Design
Authors: Zheng Guoping , Liu Cheng , Li Cheng
Published: November 2019

Path following of underactuated marine vessels is a fundamental marine practice in shipping industry. However, the collision avoidance, which is frequently encountered during the process of path following of ships sailing in seaways, is neglected in traditional studies of path following. In this paper, a novel control design for path following with auxiliary system for collision avoidance is presented. Taking advantage of the capability of dealing with multi-variable system with the constraints, the model predictive control (MPC) method is employed to deal with the input saturation (rudder) and underactuated problem. Furthermore, the parallel computational nature of projection neural network (PNN) is included to reduce the computational burden of traditional MPC technique and make the control design more efficient. Simulations are conducted to validate the effectiveness and efficiency of the proposed control design.
Designing Coastal Structures for Tsunami Loads per ASCE 7-16
Authors: Robertson Ian N. , McKamey Jacob
Published: November 2019

The 2016 edition of ASCE 7, Minimum Loads and Associated Criteria for Buildings and Other Structures, contains a brand new Chapter 6 on Tsunami Loads and Effects. This new chapter applies to the tsunami design of all Risk Category III (high occupancy) and IV (essential) buildings, and potentially many taller Risk Category II (regular) buildings, in coastal communities in Alaska, Washington, Oregon, California and Hawaii. These provisions can also be applied to other communities exposed to tsunami hazard, including Guam, American Samoa, Puerto Rico, and communities outside the US.

This paper shows an example of how the new tsunami design provisions would apply to the design of prototypical multi-story coastal reinforced concrete buildings at different locations on the US Pacific Coast. The prototypical Risk Category II buildings are located in Seaside OR, Monterey CA, Waikiki HI and Hilo HI. Economic consequences of including tsunami design for mid- to high-rise Risk Category II buildings are discussed.
Fracture Mechanics Based Mooring Fatigue Analysis for a Semi-Submersible Subjected to Triple Narrow-Band Loading Processes
Authors: Xue Xutian , Chen Nian-Zhong , Pu Yongchang
Published: November 2019

In the general offshore operating locations, mooring systems are normally considered to be primarily affected by environmental loadings induced by waves, wind and current. WF motion induced by first-order waves, LF motion induced by second-order waves and wind would make the most contribution to the fatigue damage of mooring lines. However, it was reported recently that in the Gulf of Mexico (GoM), the fatigue life of mooring lines can be significantly affected by the vortex induced motion (VIM) induced by loop current. The aim of this presented paper is to address the influence of VIM on fatigue life of the mooring system operating at the central of the GoM through performing a fracture mechanics (FM) based fatigue analysis for an offshore mooring system.

A frequency-domain mooring analysis for the semi-submersible is conducted where WF motion induced by first-order waves, LF motion induced by second-order waves and wind, and VIM induced by loop current are taken into account. WF motion, LF motion and VIM are treated as three independent loading processes. A wide-band loading combination method is then used for predicting the loading processes acting on the mooring system combining WF motion, LF motion and VIM. A fracture mechanics based analysis is performed to examine the fatigue life of mooring system, in which initial surface cracks in previous existence are assumed to grow from the surfaces of mooring chain links connecting to the fairleads. The stress intensity factor ranges to estimate the crack growth in the FM based analysis are obtained from a finite element (FE) analysis.
Quantitative Evaluation of Ship Operational Effect in Actually Encountered Sea States
Authors: Miratsu Rei , Fukui Tsutomu , Matsumoto Toshiyuki , Zhu Tingyao
Published: November 2019

Since ships are being operated under consideration of the safety for lives and properties, economical reasons and so on, the sea states in natural phenomena and those actually encountered by ships are thought to be different, the latter has some effects of human operational factors (called as “ship operational effect”). Evaluating the ship operational effect in detail is important to consider rational wave design loads for hull structure strength.

The purpose of this study is to evaluate the ship operational effect in actually encountered sea states quantitatively. As the first report, comparison was made between IACS Rec.34 (a kind of the observed sea states in natural phenomena) and forecasted sea states corresponding to AIS data of ships (a kind of the sea states data actually encountered by ships) on the North Atlantic. Comparisons among the encountered significant wave heights by merchant ships such as bulk carriers, oil tankers and container ships and those specified in IACS Rec. 34 were carried out. Furthermore, the wave headings regarding the encountered waves were investigated. Finally, the relationships between encountered significant wave heights and ship speeds were derived to confirm the ship operational effect.

It was confirmed from the results that the actually encountered wave heights were smaller than those in IACS Rec. 34, through comparing the exceedance probability of the significant wave heights for each type of ships and IACS Rec. 34. The exceedance probability in the encountered beam seas is relatively lower compared with those in the encountered head and following seas. The results also show that ship speeds decrease when the encountered wave heights become larger.
Slamming Force Contribution due to Plunging Breakers on Circular, Square and Diamond Cylinders
Authors: Wang Xin , Dev Arun Kr , Tao Longbin , Chia De Wang , Zhang Yali
Published: November 2019

Plunging breakers, unlike non-breaking waves, impose additional slamming load on the offshore structures. This additional slamming load is considered an extreme event and is one of the most devastating forces that an offshore structure could encounter during its operational lifecycle.

Whilst there are design guidelines for offshore structures pertaining to breaking waves, however it is limited to only cylindrical shape. The amount of slamming load contribution by the plunging jet is also dependent on the cross section geometries of the offshore structures. Different geometries would give rise to different air entrainment phenomenon during wave breaking and therefore affecting the slamming load contributions.

In this research, JONSWAP spectrum was used to create plunging breakers via the focusing method at Newcastle University’s Wind Wave and Current tank. The crux of this research is to investigate the wave-breaking impact load on cylindrical structures with different cross section geometries commonly used in the offshore industry.
A Fast 3D Model for Annular Flows of Wellbore Completion Fluids
Authors: Tardy Philippe M. J.
Published: November 2019

This paper presents a novel approach to solving the 3D flow and displacement of completion fluids in the annulus formed by the gap between the outer wall of the casing and the wellbore rock face. Completion fluids displace each-other and follow a complex path promoted by rheology and density contrasts, casing movement and by the shape and orientation of the annulus. Muds and cement slurries often exhibit a yield stress, an additional challenge for optimal mud removal and cement coverage. This work extends previously published 2D models, to now capture fluid distribution and velocity profiles across the gap width in the 3D axial-azimuthal-radial space, at a lower computer cost than with conventional 3D CFD approaches. This gain is obtained by solving a 2D-only pressure equation for calculating the 3D annular flow, under the so-called narrow-gap approximation.
Strength and Fatigue Performance of Steel Lazy Wave Risers With Change in Configuration Parameters
Authors: Lal Mayank , Wang Feng , Lu Xiaohua , Sebastian Abhilash
Published: November 2019

Steel Lazy wave risers are being increasingly used for deep water applications due to better strength and fatigue performance in the touchdown zone compared to steel catenary risers. Several parameters govern the design of steel lazy wave risers including the length of the catenary from hang-off to start of buoyancy section and the length of the buoyancy section. In this paper, a parametric study is performed to investigate the trends in strength and fatigue performance of steel lazy wave risers with change in configuration parameters. A normative cost assessment is also performed to show the impact of these design variables on overall cost of the system.

Dynamic analysis is performed to check the change in strength and fatigue performance of steel lazy wave risers as the configuration parameters are changed. The results from the parametric study will assist in designing steel lazy wave risers which satisfy the strength and fatigue design criteria.