bluuebunny/crossref_metadata_2025 huggingface dataset:
Extracting Customer Perceptions of Product Sustainability From Online Reviews
Authors: El-Dehaibi Nasreddine , MacDonald Erin F.
Published: November 2019

In order for a sustainable product to be successful in the market, designers must create products that are not only sustainable in reality, but are also sustainable as perceived by the customer — and reality vs. perception of sustainability can be quite different. This paper details a design method to identify perceived sustainable features (PerSFs) by collecting online reviews, manually annotating them using crowd-sourced work, and processing the annotated review fragments with a Natural Language machine learning algorithm. We analyze all three pillars of sustainability — social, environmental, and economic — for positive and negative perceptions of product features of a French press coffee carafe. For social aspects, the results show that positive PerSFs are associated with intangible features, such as giving the product as a gift, while negative PerSFs are associated with tangible features perceived as unsafe, like sharp corners. For environmental aspects, positive PerSFs are associated with reliable materials like metal while negative PerSFs are associated with the use of plastic. For economic aspects, PerSFs mainly serve as a price constraint for designers to satisfy other customer perceptions. We also show that some crucial sustainability concerns related to environmental aspects, like energy and water consumption, did not have a significant impact on customer sentiment, thus demonstrating the anticipated gap in sustainability perceptions and the realities of sustainable design, as noted in previous literature. From these results, online reviews can enable designers to extract PerSFs for further design study and to create products that resonate with customers’ sustainable values.
Shared Control Strategy for Vehicle Stability on U-Split Road
Authors: Yu Liangyao , Abi Lanie , Lu Zhenghong , Dai Yaqi
Published: November 2019

The steer-by-wire (SBW) system eliminates the mechanical connection between the steering wheel and the carriage wheel. It eliminates various limitations of the traditional steering system, so that the steering ratio of the car can be freely designed and the steering by wire system can achieve good active front wheel steering (AFS) function. In the study of the stability control of vehicles on the μ-split road, there are mainly two methods, one based on vehicle trajectory maintenance and the other based on vehicle dynamic stability control. Both of these control methods have delays, which is not conducive to the trajectory flowing ability of the vehicle when driving on the μ-split road. A shared control strategy is proposed to improve the vehicle’s stability. The purpose of this study is to establish different variable transmission ratio characteristic curves according to the different input signals of the driver and the vehicle, such as angular change speed, steering wheel angle, etc. Based on these conditions, a new model combining driver’s intention with vehicle dynamic model is established, so as to achieve the purpose of judging the stability of vehicle in advance, to reduce the delay time of control and to improve the response speed, which will improve the stability performance of the vehicle.
Smart and Autonomous Farm Field Scouting Service Robot As an Edge Device Under $1000: Challenges and Opportunities
Authors: Tian Junwei , Niu Haoyu , Wang Peng , Chen YangQuan
Published: November 2019

Smart farming focuses on the application of intelligent and autonomous machines to make agricultural production more effective. The development of Agriculture Unmanned Ground Vehicle (AUGV) makes it possible to utilize smart, small, intelligent robots in agriculture. Even existing AUGVs have been used in many fields, their disadvantages have limited the promotion of current AUGV system. Based on the demands of farmers, a new Low Cost Smart Agriculture Unmanned Ground Vehicle (LCS-AUGV) system is proposed. The challenges and opportunities of LCS-AUGV are discussed, and the frame work of LCS-AUGV is designed. The designed LCS-AUGV includes two subsystems: Unmanned Ground Vehicle System (UGVS) and Remote Control System (RCS), and diagrams of each subsystem are designed and described in detail. The measuring and control system (MCS) of LCS-AUGV is designed, and hierarchical structure is introduced into MCS. The new MCS principle can add or remove super information center easily, thus the high performance and low cost of the system can be taken into account. Based on the proposed MCS, a five-level control strategy is designed. The designed control strategy includes Basic Level Control (BLC), Low Level Control (HLC), Super Level Control (SLC), Agriculture Mission Based Control (AMBC). A LCS-AUGV platform is built at the basis of the designed frame work, and the cost analysis is performed. According to the analysis, the hardware cost can be controlled below $1000, while most super function can be realized. The typical applications also are described. LCS-AUGV provides an ideal platform for most smart farming tasks and is easily to be accepted by farmers. The LCS-AUGV also can be used in high level intelligence agriculture field, and be selected as a new algorithm’s research platform.
Modeling a Supply Chain Reference Ontology Based on a Top-Level Ontology
Authors: Ameri Farhad , Kulvatunyou Boonserm
Published: November 2019

Several supply-chain ontologies have been introduced in the past decade with the promise of enabling supply chain interoperability. However, the existing supply-chain ontologies have several gaps with respect to completeness, logical consistency, domain accuracy, and the development approach. In this work, we propose a new, supply-chain, reference ontology that is 1) based on an existing top-level ontology and 2) developed using a collaborative, ontology-development, best practice. We chose this approach because empirical studies have shown the usefulness of adopting a top-level ontology both for improving the efficiency of the development process and enhancing the quality of the resulting ontology. The proposed proof-of-concept reference ontology is developed in the context of the Industrial Ontology Foundry (IOF). IOF is an international effort aimed at providing a coherent set of modular and publicly-available ontologies for the manufacturing sector. Although the proposed reference ontology is still at the draft stage, this paper shows that it has already benefited from the collaborative development process that involves inputs from the other working groups within IOF. Additionally, as a way to validate the proposed reference ontology, an application ontology related to a supplier discovery and evaluation use case is derived from the reference ontology and tested.
Improvement of Admissibility of Linear Singular Fractional Order Systems
Authors: Zhang XueFeng , Zhang Yingbo
Published: November 2019

This paper considers the least solutions of linear matrix inequalities (LMIs) in criteria of admissibility for continuous singular fractional order systems (FOS). The new criteria are given which are strict LMIs and do not involve equality constraint and with the less LMI decision variables. With brief and simple results of this paper, the numbers of solved matrices are reduced from a pair of matrices to just a matrix in which we can analyze singular fractional order systems with completely consistent format as normal systems.
Design of NRL66.4: An Electro-Hydraulic 6-DoF Parallel Robotic Multiaxial Material Testing System
Authors: Michopoulos John G. , Iliopoulos Athanasios P. , Steuben John C. , Graber Benjamin D.
Published: November 2019

Contemporary material testing applications such as high throughput material testing under realistic conditions, emulation of in-service loading conditions for the qualification of additively manufactured parts, material failure and damage propagation modeling validation and material constitutive characterization, are all underscoring the demand for an automated multiaxial testing capability. In order to address these needs, the present work introduces the initial progress of the design and prototyping of a 6 degrees of freedom (6-DoF) robotic system to be used as such a testing infrastructure. This system is designed to be capable of enforcing 6-DoF kinematic or force controlled boundary conditions on deformable material specimens, while at the same time measuring both the imposed kinematics and the corresponding reaction forces in a fully automated manner. Furthermore, as an extension to our previously prototyped systems, the system proposed here is designed to apply both quasi-static loading but also cyclic loading for enabling multiaxial fatigue studies. In addition to the architecture, the design and current status of its implementation for the most critical sub-systems is presented.
Designy: A Multimedia Platform for Supporting Student Prototyping in Product Design Education
Authors: Ramos Joshua D. , Wallace David R.
Published: November 2019

In product design courses, prototyping offers a way for students to develop physical intuition about materials while practicing techniques used by professional designers. A web-based platform was developed to explore the use of multimedia to provide students with additional support for prototyping activities. The result is Designy (www.productdesigny.com), a platform containing a series of photo- and video-based resources meant to help students prototype effectively. Students in two product design classes — 2.00b Toy Product Design and 2.744 Product Design — were given access to Designy to aid in their project work. To better understand whether the platform was utilized by students and if access to the platform contributed to student learning and project work, researchers analyzed website activity data and interviewed students (n = 19) to collect data regarding their experiences with the platform. A core group of 24 students (27%) in 2.00b and 29 students (35%) in 2.744 generated the most activity on the platform. Interview data indicates that students used the platform to answer prototyping-related questions when designing, to better understand the landscape of prototyping tools available to them, and to increase a feeling of confidence working in a prototyping shop.

Overall, results suggest that while in-person interactions with staff members can better help students in situations where the support students need is poorly identified, Designy was shown to provide efficient support in situations when students could clearly identify the type of support they needed.
Design of Four-, Six-, and Eight-Bar Linkages for Rectilinear Movement
Authors: Liu Xueao , Glabe Jeffrey , Wu Hongyu , Wang Chunjie , McCarthy J. Michael
Published: November 2019

This paper examines the results of synthesis algorithms for four-, six-, and eight-bar linkages for rectilinear movement. Rectilinear movement is useful for applications such as suspensions that provide linear movement with out a rotation component. The algorithm yields one four-bar, seven six-bar, and 32 eight-bar linkages. The synthesis strategy begins with a task guided by a multi-degree of freedom chain. The algorithm computes constraints to guide the required movement with one degree-of-freedom. Each computed design is analyzed to ensure smooth movement through the specified set of task positions. Finally, we identify the design that has the least variation from a pure rectilinear movement.
A Methodology to Experimentally Investigate the Impact of Wobble Errors on the Contact Pattern and Static Transmission Error of Helical Gear Pairs
Authors: Benatar Michael , Handschuh Michael , Kahraman Ahmet , Talbot David
Published: November 2019

For a gear pair, both the contact pattern and the transmission error (TE) significantly impact durability and fatigue life. Design and manufacturing processes are often aimed at improving the contact pattern and reducing the overall TE. Other errors, such as runout and wobble, are often induced during the installation of power transmission systems, and they can alter the contact pattern and TE of an otherwise well-designed gear pair.

This study provides a methodology to experimentally investigate the impact of wobble errors on the contact pattern and static transmission error (STE) of helical gears. It first provides a description of the modifications to an existing test machine. Next, it describes the gear specifications, preliminary testing matrix, data acquisition and processing procedure, as well as the experimental results obtained with regards to both the contact pattern and STE.

The following are observed while describing the experimental results. For a test with no wobble and no runout, the contact pattern remains the same at every rotational position. However, by introducing even a small amount of wobble, the contact will shift from one side of the face width of the gear to the opposite side of the face width of the gear within one revolution. Introduction of wobble may increase the STE and sideband activity around gear mesh harmonics, especially as torque increases. Yet the modest increases in STE and sideband activity seen with the introduction of wobble are not enough to make definitive conclusions.

The feasibility of the modified test setup has been demonstrated, and preliminary results have been presented. However, additional data collection should be completed in order to study the impact of runout and wobble on both spur and helical gear pairs with various microgeometry modifications and manufacturing errors.
An Excess Based Approach to Change Propagation
Authors: Long Daniel , Ferguson Scott
Published: November 2019

This research demonstrates how the Decision Based Design (DBD) approach can be used for determining a system’s lifecycle value when including excess. Prior research has shown that excess (the degree to which a component or attribute is sized beyond the minimum required to support the initially fielded system) can reduce the cost of changing a system. Theoretically, excess inhibits change propagation within a system and could be strategically added to increase the value of that system. Including excess, however, also adds cost and potentially impacts system performance. Prior research has not quantitatively linked excess as a means of limiting change propagation to system lifecycle value. This work advances the existing literature by considering how excess is imbedded in a system and what impact excess has on the system’s total value. After being introduced, the method is demonstrated on a desktop computer example. Results from the study are used to show how decisions about power supply capacity can be optimized by incorporating excess to achieve flexibility.
On the Spectro-Spatial Wave Features in Nonlinear Metamaterials With Multiple Local Resonators
Authors: Bukhari Mohammad A. , Barry Oumar R.
Published: November 2019

Considerable attention has been given to nonlinear metamaterials because they offer some interesting phenomena such as solitons, frequency shifts, and tunable bandgaps. However, only little is known about the spectro-spatial properties of a wave propagating in nonlinear periodic chains, particularly, a cell with multiple nonlinear resonators. This problem is investigated here. Our study examines both hardening and softening nonlinearities in the chains and in the local resonators. Explicit expressions for the nonlinear dispersion relations are derived by the method of multiple scales. We validate our analytical results using numerical simulations. The numerical simulation is based on spectro-spatial analysis using signal processing techniques such as spatial-spectrogram and wave filtering. The spectro-spatial analysis provides detailed information about the interactions of dispersive and nonlinear phenomena of waveform in both short and long-wavelength domains. The findings suggest that nonlinear resonators can have more effect on the waveform than the nonlinear chains. This observation is valid in both short and long wavelength limits.
Development of a Coding Scheme for Qualitative Analysis of Student Motivation in Senior Capstone Design
Authors: Shah Devanshi , Kames Elisabeth , Clark McKenzie , Morkos Beshoy
Published: November 2019

Senior Capstone Design courses offer two major types of projects: industry sponsored projects and non-industry sponsored projects. Previous studies show changes in student motivation based on the type of project they select. However, the quantitative data analysis fails to capture the reasoning behind the student’s inclination towards a certain type of project in the beginning of the selection phase. Also, little is known about the personal experiences of the student working on the team and project they choose. This paper addresses the gap in the examination of student motivation based on the type of projects they select. This paper outlines a coding scheme developed to analyze the qualitative interview data gathered during an open-floor style exit interview with all of the senior design teams. The thirty minute exit interviews were conducted at the end of the semester to capture their experiences and reflections about the course. A coding manual is generated which highlights the codes observed frequently among the teams. Themes are developed highlighting the important phases of the course. The objective is to develop a coding scheme for senior capstone design courses which would serve as a guide to the educators to determine various factors that influence student motivation and improve the senior design experience for all students.
Do Capstone Students Really Understand the Needs of the Customer?: Observations on Students’ Blind Spots Left by Early Program Curriculum
Authors: Goodson Matthew , Sorensen Carl , Anderson Michael , Mattson Christopher
Published: November 2019

Student capstone teams have varying degrees of success in meeting the expectations of their project sponsors. Keeping sponsors happy is important to these programs in order to ensure continued support from these industry representatives, so finding ways to improve project outcomes is critical. In order to find blind spots that students may have been left with after their first 6–7 weeks of instruction, we conducted structured interviews with students in capstone programs at Brigham Young University and the US Air Force Academy. These interviews were then transcribed, coded, and analyzed for themes that may have been well understood or misunderstood by students. We found that a significant number of students had not understood concepts such as a design being more than a prototype, that sponsors have expectations for the tradeoffs between product cost and performance, or that they need to be thinking about how their designs might be deployed. It was also interesting to note that most students also reported feeling confident in their understanding despite their apparent lack thereof, indicating that these could represent major blind spots for students. We propose that developing methods for teaching these principles early on will help students see more clearly what their end goals need to be, and thus help them be more successful in delivering desirable designs.
Mobile Based Real-Time Occlusion Between Real and Digital Objects in Augmented Reality
Authors: Jain Pranav , Tucker Conrad
Published: November 2019

In this paper, a mobile-based augmented reality (AR) method is presented that is capable of accurate occlusion between digital and real-world objects in real-time. AR occlusion is the process of hiding or showing virtual objects behind physical ones. Existing approaches that address occlusion in AR applications typically require the use of markers or depth sensors, coupled with compute machines (e.g., laptop or desktop). Furthermore, real-world environments are cluttered and contain motion artifacts that result in occlusion errors and improperly rendered virtual objects, relative to the real world environment. These occlusion errors can lead users to have an incorrect perception of the environment around them while using an AR application, namely not knowing a real-world object is present. Moving the technology to mobile-based AR environments is necessary to reduce the cost and complexity of these technologies. This paper presents a mobile-based AR method that brings real and virtual objects into a similar coordinate system so that virtual objects do not obscure nearby real-world objects in an AR environment. This method captures and processes visual data in real-time, allowing the method to be used in a variety of non-static environments and scenarios. The results of the case study show that the method has the potential to reduce compute complexity, maintain high frame rates to run in real-time, and maintain occlusion efficacy.
Exploration of Layer Specific Dimensional Multipliers in Modified Unit Cell Synthesis Method Meta-Materials for Nonlinear Applications
Authors: Franklin Samuel J. , Fadel Georges , Coutris Nicole , Li Gang , Castanier Matt
Published: November 2019

Topology optimization of periodic metamaterials for structural applications usually results in uniformly distributed cells. This paper presents a novel concept designed to better tailor unit cell-based meta-material designs for nonlinear structural applications. First, previous work in the development of a systematic method for the construction and optimization of these advanced materials is reviewed. Results of a previous case study for the design of meta-material backer pads for the wheels of the Abrams tank are presented to provide a platform for the introduction of layer specific dimensional multipliers, dubbed “size factors”. These add an additional layer of complexity for the previously designed homogeneous materials. The methodology behind the size factors is presented and the implementation of the “size factors”, as it pertains to the meta-materials designed using the Modified Unit Cell Synthesis method, is then discussed. Initial assumptions for a final size factor arrangement are presented, prompting the creation of two optimization procedures to compare against one another. Results for both optimizations are obtained and while both show an increase in nonlinearity over the original material, the unorganized arrangement of the parameters results in the most optimal designs, with near zero error between the target and obtained non-linear force-strain relationships.
Analysis of Designer Emotions in Collaborative and Traditional Computer-Aided Design
Authors: Zhou Jinxuan (Janice) , Phadnis Vrushank , Olechowski Alison
Published: November 2019

Technology is transforming the way engineering designers work and interact with others; Synchronous collaborative computer-aided design (CAD) tools allow designers to manipulate the same model at the same time. We present a new method using automated facial emotion detection software and cursor tracking to map designer emotions and corresponding designer activities in synchronous collaborative CAD. We present findings from a dataset of 9 participants that were assigned to two distinct working styles in the same synchronous CAD environment: single participants working by themselves and paired participants working together. In general, our results show that designers working in the paired workflow exhibited more emotion compared to designers who worked alone. A frequency analysis was performed by linking occurrences of each emotional response to their antecedent activities, revealing that user emotions were predictable to some degree by specific antecedent activities of CAD work. We concluded that activities happening in the graphics area were the most frequent antecedent events of emotions for single-users, while for paired participants, activities in the chat section and feature menu were the most frequent antecedent events for joy and fear, respectively. Finally, logistic regression was applied for each combination of event and emotion for each participant in order to further investigate the relationships between the user activities and emotions, and meta-regression was used to aggregate the regression results for the two different working styles. In particular, for single-users, activities in the model tree were found to be positively correlated to joy and negatively correlated to disgust, and navigating the feature menu increased the likelihood of contempt. For participants in pairs, communicating with CAD partner and receiving communications from partner was associated with joy, navigating the feature menu was associated with sadness, anger and disgust were associated with partner’s action in the model tree, and contempt corresponded to the designer’s own activities in the model tree area. The approach and conclusions presented in this paper allow us to better understand designer emotions in fully synchronous CAD, which leads to insight related to designer satisfaction, creativity, performance and other outcomes valued by engineering designers in a virtual collaborative environment.
Effect of Humidity on the Nanoscale Heat Transfer at the Head-Media Interface
Authors: Cheng Qilong , Ma Yuan , Bogy David
Published: November 2019

In hard disk drives (HDD), the head-media spacing has decreased to less than 10 nm. Across this nanoscale gap, the heat transfer between the head and media may affect the air-bearing design, lubricant transfer and contact issues. Thus, understanding the heat transfer mechanism is very important to magnetic recording, especially for Heat Assisted Magnetic Recording (HAMR). In this paper, the heat transfer between a head and a static media is studied. In particular, the effect of humidity on the nanoscale heat transfer between a head and a static media is studied experimentally. From the transient and steady data of the experiments, it is proposed that the dynamic response of head protrusion is faster than heat dissipation. Also, a layer of water is assumed to form between the head and the media under high humidity. The water-layer affects the spacing and the heat transfer coefficient across the interface. In the near-contact regime, namely when the clearance is less than 2 nm or so, the protrusion interacts with the water-layer on the media, resulting in a lower rate of change of cooling.
Establishment of Mass Production Method of Mesoporous Silica Thin Film and Development of Porous Carbon Thin Film Using 1,4-Dihydroxyanthraquinone As Carbon Source
Authors: Tamada Makio , Sunami Yuta
Published: November 2019

Porous materials typified by mesoporous silica and porous carbon are expected to be applied in various fields such as adsorption, ion exchange, and engineering. In this research, we focused on mesoporous silica thin films and porous carbon thin films. For the mesoporous silica thin film, mass creation method was established the by introducing the roll-to-roll fabrication method. In this method, the pore size could be controlled by changing the molar ratio of the precursor solution, and the thickness of mesoporous silica film is controlled by changing the peripheral speed ratio. In the development of porous carbon thin film, we succeeded to express pores by using 1,4-dihydroxyanthraquinone as a carbon source. X-ray analysis and arithmetic mean roughness measurements were made on the fabricated carbon thin film. As a result, it was confirmed that the porous carbon thin film prepared in this study has a higher specific surface area than the porous carbon thin film synthesized by the conventional manufacturing method.
A New On-Chip Real-Time Algorithm for Non-Invasive Cuffless Blood Pressure Estimation Using PPG Sensor
Authors: Yeh Ming Hua , Chao Paul C.-P. , Pandey Rajeev
Published: November 2019

Blood pressure is a basic physiological quantity and prolonged abnormal blood pressure which will precipitate different kinds of cardiovascular diseases. The early detection of hypertension is extremely important for the prevention and cure of cardiovascular diseases. This study proposes a new on-chip real-time algorithm for non-invasive cuffless blood pressure estimation using PPG Sensor (PPG). The algorithm is implemented in the integrated chip with chip area of 3.97mm2 and fabricated via TSMC T18 process. The experimental result shows that the overall power consumption of the chip is 15.62 mW. Finally, the blood pressure measurement platform has been developed with GUI for long-term continuous cuffless BP measurement. The non-invasive blood pressure sensor is applied to the wrist artery of 44 subjects for sensing the PPG pulsation of the blood vessel. Measurement results shows that the maximum error in the BP measurement is ±6 mmHg. Which is less than 8 mmHg, defined by the Advancement of Medical Instrumentation (AAMI) and British Hypertension Society (BHS) standard.
Realization of Natural User Interface for Computer Control With KNN Classifier Enhanced Smart Glove
Authors: Wu Chieh-Ju , Lin Kai-Hsiang , Hsieh Meng-Lin , Chang Jen-Yuan (James)
Published: November 2019

Gesture interaction is a commonly used solution when introducing Natural User Interface (NUI), a kind of user interface where the interaction is direct and consistent with natural heuristic behaviors. In this paper, a smart glove with efficient real-time hand orientation calculation and accurate static hand gesture prediction is proposed. This custom-built wireless glove consists of flex sensors, an Inertial Measurement Unit (IMU) sensor, a microcontroller with multi-channel ADC/AMP (analog to digital converter and amplifier), a Bluetooth module, and an Arduino Micro Pro. K-Nearest-Neighbor (KNN) classifier is implemented to assist static hand gesture prediction with the validated accuracy exceeding 97%. This supervised machine learning algorithm allows a highly customizable smart glove which the input gestures, input number of gestures, and the associated activating functions are all easily changeable by the users any time. To show the benefits of combining the NUI and supervised machine learning, a validation experiments, computer control, were conducted.
Failure Detection for Multiple Micro-Punches Outfitted in Progressive Piercing Processes With Artificial Intelligent Model
Authors: Wu Tsung-Liang , Hwang Yu-Chun
Published: November 2019

The purpose of this study is to establish a model for the diagnosis of multiple micro-punch failures. The punch is assumed to a rigid body structure with a small change in the stiffness during the piercing process and its diameter is varied between Ø0.8–1.2 mm. Thus, the wearing trend of multiple punches in the piercing process and source of the interfered signals make it extremely difficult to analyze. The two major challenges that affect punch failure estimation are the poor signal-to-noise ratio within the factory environment and the rigid body mode disturbance in the signal. To acquire the vibratory signals of the piercing motion, uniaxial accelerometers were outfitted in the vertical direction on the progressive die. Since the piercing process is a series of highly nonlinear transient processes, the Ensemble Empirical Mode Decomposition (EEMD) is adopted as a decoupling operation tool for this kind of non-stationary signal. Furthermore, the dimension-reduced process can be manipulated by Intrinsic Mode Function (IMF) and a function representative of the feature is selected as the input for neural network model training. The training target is the most direct relationship with the product quality, the selected models are multi-layer perceptron and the back-propagation neural network (BPNN) of the error inversion algorithm. The artificial intelligence failure diagnosis of the piercing process is also realized.
Inverse Kinematics of a Humanoid Robotic Arm With Fixed Joint Method
Authors: Deng Yu-Heng , Chang Jen-Yuan (James)
Published: November 2019

In this paper, we propose a new algorithm to solve the inverse kinematics problem. It would adaptively limit the movability of certain joints during the iteration process of inverse kinematics according to the pose of the manipulator and the target position. This change could prevent lower links to get tangled and cause a singularity. Our research is based on a model of a 7-DOFs (degree of freedoms) humanoid robotic arm, and the parameter study of the inverse kinematics algorithm has been done to increase both success rate and decrease calculation time. This paper provides a fast and low computational cost scheme to calculate inverse kinematics with the ability to reduce the chance of encountering the singular points.
Design of a Novel Variable Stiffness Series Elastic Actuator for Extended Linearity
Authors: Lee Seung Ho , Lee Hyeok Jin , Lee Kyeong Ha , Baek Ji Min , Koo Ja Choon
Published: November 2019

Recently, Series Elastic Actuator (SEA) has been popularly used as a torque sensor thanks to its notable ability to calibrate the relation between torque and displacement. It has been applied to many robotic applications and used in a various industrial automation fields. However, most of the current SEAs have nonlinear torque-displacement characteristics which could not be easily alleviated. In order to be utilized as a feasible torque sensor, the wide linearity of a SEA in torque-displacement relationship is not an option. Also, adjustable compliance is needed to implement a mechanism with different stiffness, depending on the various cases where SEA can be applied. In this paper, we designed a Variable Stiffness Linear Series Elastic Actuator (VLSEA) mechanism that can achieve variable stiffness with a linear relationship between torque and displacement. At first, a design with a four-bar link was proposed for linear relations, but it was difficult to implement variable stiffness. We modified the design using the Scotch Yoke mechanisms for the model to have variable stiffness. Simulation of the designed model then verifies that the model can properly implement linearity and variable stiffness.
Modelling of the Movement of a Prolate Particle in the Steady State Flow of a Non-Newtonian Fluid in an Inclined Annulus With Inner String Rotation
Authors: Cayeux Eric
Published: November 2019

The determination of the slip velocity, or whether a solid particle will sediment, during its transport is of prime importance for hole cleaning evaluations during drilling operations. Yet, this task is complexified by the asymmetry of the annulus when the central pipe axis does not coincide with the borehole central line and when the inner string rotates, especially since drilling fluids typically follow a yield stress power law rheological behavior.

This paper describes the modelling of the movement of a particle in such conditions yet with the following simplifications: the inner tube is eccentric but has a uniform movement, the shape of the particle is assimilated to a prolate, the change of shear rates in the fluid around the slipping particle is neglected and collisions between particles are not considered. Otherwise, gravitational effects are incorporated by accounting for the mass density difference between the particle and the surrounding fluid mixture and by considering the borehole inclination. The particle spin is also estimated as it plays an important role in the determination of the drag and lift forces.

The solution to the differential equations that describe the time evolution of the position and orientation of the particle, depend largely upon the initial conditions. Therefore, an ensemble of boundary conditions is generated at a starting cross-section along the annulus and the resulting particle trajectories are estimated. It is then possible to estimate a probabilistic slip velocity for particles of the considered dimensions, far away from the entrance region. This probabilistic approach allows to define a critical transport fluid velocity as the lower limit of the bulk fluid velocity by which no particle risk to settle. Similarly, one can define a critical settling fluid velocity as the upper limit of the bulk fluid velocity where every particle will sediment regardless of the initial conditions.

With the described modelling of the particle movement and its associated statistical methods, it is possible to quantitatively estimate the spatial distribution of particles in any cross-section. For those particles that get trapped between the tool-joint and the borehole, it is then possible to estimate their size reduction by grinding, resulting from the rotation of the tool-joint on the borehole wall. The grinding process impacts the particle size distribution passed a tool-joint. By applying this method iteratively up to the annulus outlet, it is possible to estimate the particle size distribution of the drill-cuttings when they arrive at the shale-shakers.
Small-Scale HISC Testing of a Superduplex Stainless Steel Welded Joint: The Impact and Interaction of Testing and Residual Stresses
Authors: Blanchard Lisa , Sotoudeh Kasra , London Tyler , Kabra Saurabh
Published: November 2019

The combination of high strength and corrosion resistance of duplex stainless steels (DSSs) has promoted their use in subsea environments, particularly for the oil and gas industry. However, in the past 20 years, costly in-service failures of DSS components have frequently been encountered, most of which were attributed to hydrogen induced stress cracking (HISC). This cracking mechanism occurs once a susceptible microstructure coexists with critical levels of hydrogen and stress. In subsea environments, the use of cathodic protection (CP) is a source of hydrogen and the critical stress levels can be reached locally by operation and residual stresses generated during the manufacturing and installation processes. In order to prevent HISC failures, the microstructure, sources of hydrogen and stress levels have to be determined and controlled.

An important factor contributing to the total stress experienced by a welded component is the residual stresses induced by welding. In a previous research projects conducted at TWI, residual stresses were measured in a full-scale girth weld between a DSS flange and pipe which had been in service, subsea, for 12 years.

This follow-on work, on the same component, tested a number of small-scale cross-weld specimens, under CP to evaluate resistance to HISC of the weld. The observations showed that the cross-weld specimens exhibited superior resistance to HISC than that of the all-parent pipe and flange specimens. This was unexpected, and it was thought that this could potentially be explained by the influence of any compressive residual stresses remained in the small-scale test specimens used for the environmental testing programme.

The present work provides the residual stress measurements in small-scale cross-weld specimens, using the neutron diffraction technique, and attempts to explain the relationship between the HISC testing results and residual stresses measured.
Tie-in of a Rigid Pipeline to a Flexible Rise: Design and Installation — Challenges and Lessons Learnt
Authors: Curti Gianbattista , Lirola Francois , Pirinu Gianluigi , Pavone Diego , Perrin Frederic
Published: November 2019

This paper presents the experience made with the engineering and execution of the tie-in of flexible risers to rigid pipelines on a project recently completed in West Africa.

Five production and injection pipelines (10” and 6”) were tied back to the host platform with flexible risers, in Lazy wave configurations, in ∼600m water depth.

The risers are directly connected to the terminations structures (PLETs) of the rigid pipelines, through horizontal connection systems.

The structures forming the tie-in (risers, PLETs and pipelines) have been designed to accommodate axial displacements of the pipelines in the range 0.3m to 1.0m, as positive displacements (expansions) and −0.1m to −0.7m as negative displacements (contractions) of the pipelines, respectively towards and away from the risers, due to pipelines thermal expansions and pipe walking.

Note that along some of the lines anchoring structures have been installed to control pipe walking.

The tie-in interface loads were to be limited, in order not to threaten the flexible pipe, the PLETs and the connectors, and, despite the small pipeline end displacements, keeping the interface loads within allowable values, was a challenge.

The positive displacements were causing interface loads as high as 80% of the allowable values, while the negative displacements were causing up to 90% utilization of the capacity of the connectors and 95% of the allowable loading of the foundations of the PLETs.

The main drivers of such high loadings are the stiffness of the flexible pipe, combined with the layout of the tie-in.

Extensive in place analyses were done to simulate the effects of progressive displacements of the pipelines, the pipe-soil interactions and the specifics of the behaviour of the flexible pipes (hysteretic stiffness).

Full 3D FE analyses of the foundations (mud mats) of the PLETs were done, to circumvent the limitations of a classical bearing capacity analysis approach.

As built information were also used, to remove some conservatisms in the assumptions initially taken in the design. A special installation procedure was implemented, to achieve a layout of the riser at the approach of the pipeline capable to better relieve the displacements of the pipelines and reduce interface loads.

Feedbacks from the installation are given in the paper.

The lessons learned are also presented: a “flexible” pipe is a “stiff” structure and a direct tie-in to the pipeline may become an issue, if not addressed early enough during the execution of the project, when it can be too late to add mitigation structures, like intermediate tie-in spools, or to change significantly the routing of the risers and pipelines.
Operational Safety Risk Assessment in Offshore Oil Wells
Authors: Jaculli Marcelo A. , Colombo Danilo , Mendes José Ricardo P. , Marculino Cinara F. G. , Costa Beethoven G. dos S.
Published: November 2019

Identifying and analyzing hazards and their associated risks have been a major concern of the oil industry since the Piper Alpha incident in 1988, but techniques to assess risks were only explored further in the last decade after the incident in Macondo. It became clear that there were many hazards associated with oil exploration and exploitation activities; therefore, these hazards had to be identified and proper measures to contain their damage had to be put in place. This led to a development in existing risk analysis techniques such as bowtie diagrams, fault trees, Bayesian networks and Markov methods, but also hybrid techniques such as Markov chain Monte Carlo methods and fuzzy fault trees. In this work, we presented and discussed a literature review on these techniques, focusing on their contributions to the oil industry, as well as existing legislation and standards concerning safety. After comparing advantages and disadvantages of these techniques, we proposed a methodology using graphs to assess the safety level associated to a standardized sequence of operations. This methodology is based on an ontology of operations (which provides standardization) and the concept of BIS (barrier integrated sets), which are sets of elements from a well that ensure safety to perform each operation. With available statistical data, or by using fuzzy sets to cover their absence, this methodology is able to quantify reliabilities and determine if a certain operation can be performed safely based on a risk acceptance criterion. In order to demonstrate this concept, we calculated the reliability of two primary BIS during the intermediate drilling phase and showed how the reliability changes based on the corresponding drilling operational sequence.
A Study of Ship’s Frictional Resistance in Extremely Shallow Water
Authors: Zeng Qingsong , Hekkenberg Robert , Thill Cornel
Published: November 2019

In ship model tests, a model-ship correlation line (e.g., the ITTC57 formula) is used to calculate the frictional resistance of both the ship and its scaled model. However, this line is designed for deep water and the effects of water depth is not considered. Research has been conducted to improve the correlation line in shallow water, but studies of the extremely shallow water case (depth/draft, h/T < 1.2) are rare. This study focuses on the friction of two ship types in extremely shallow water, where the ship’s boundary layer cannot develop freely. The physical details are analyzed based on the data generated with Computational Fluid Dynamics (CFD) calculations. The results show that for certain ship types at the same Reynolds number, the frictional resistance becomes smaller when the water is shallower. The geometry of the ship, in addition to the Reynolds number, becomes essential to the prediction of ship’s friction in extremely shallow water. Therefore, this scenario is different from intermediate shallow and deep water, and the prediction method should be considered separately. The data and analysis shown in this study can help to improve the understanding and prediction of ship’s frictional resistance in extremely shallow water.
Numerical Study on Nonlinear Wave-Ice-Interaction
Authors: Hartmann Moritz , von Bock und Polach R. U. Franz , Ehlers Sören , Hoffmann Norbert , Onorato Miguel , Klein Marco
Published: November 2019

This paper investigates the fundamental question of nonlinear wave-ice interaction under level ice focusing on nonlinear wave propagation and dispersion of waves. Therefore, numerical investigations are performed to verify theoretically if nonlinearity takes place under level ice and if this can lead to intense wave events far away from the ice edge in order to provide an explanation for observed real-world ice break-ups. Therefore, nonlinear wave-ice interaction as well as the impact of the ice characteristics on this interaction will be investigated.

The direct numerical simulations of the nonlinear wave propagation under solid ice are performed within the Nonlinear Schrödinger Equation (NLSE) framework. The Peregrine breather solution is applied to represent exact solutions of the NLSE for a nonlinear wave group. The application of such a nonlinear wave group is predestined for the verification of occurring nonlinear wave-wave interaction below the ice sheet. For the definition of wave and ice parameters in the simulation setup, the results of the presented parameter study are used. The parameters are analyzed regarding relevant characteristics of nonlinear wave-ice interaction and wave propagation. By assuming constraints with respect to physical consistency, the parameter range for the NLSE simulations can be narrowed.

The scope of this investigation is to provide a better understanding of the ice conditions required to observe nonlinear wave effects under level ice.