bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphological Analysis of 316L Laser Powder Bed Fusion Melt-Pool via the Enriched Analytical Solution Method
Authors: Michopoulos J. G. , Steuben J. C. , Birnbaum A. J. , Iliopoulos A. P. , Aroh J. , Rollett A. D. , Gould B. 
Published: November 2020

Abstract
The recent development of the Enriched Analytical Solution Method (EASM) for evaluating the spatio-temporal distribution of the temperature fields generated during the Laser Powder Bed Fusion (LPBF) Additive Manufacturing (AM) processes is provides an opportunity to study the sensitivity of the morphological parameters characterizing the associated melt-pools as a function of process parameters. The present work exercises the EASM for the case of a single-path trace over a 316L base plate under LPBF heat deposition conditions. To assist in the evaluation of solidification parameters, the spatial derivatives of the EASM are also derived. A process parameter subspace spanned by the scan velocity and the laser power is considered and the EASM is utilized for deriving a number of geometrical morphological characteristics of the melt pool as well as the quantities controlling the evolution of the solidification front. Finally, comparisons with initial experimental results obtained by in-situ high speed synchrotron X-ray imaging, capturing the spatio-temporal evolution of the melt pool profile are also presented.
Theoretical Framework for Design for Dynamic User Preferences
Authors: Arezoomand Mojtaba , Rouse Elliott , Austin-Breneman Jesse 
Published: November 2020

Abstract
A key assumption of new product development is that user requirements and related preferences do not vary on time scales of the process length. However, prior work has identified cases in which user preferences for product attributes can vary with time. This study proposes a method, Design for Dynamic User Preferences, which adapts reinforcement learning (RL) algorithms for designing physical systems whose functionality changes with user feedback. An illustrative case comprised of the design of a variable stiffness prosthetic ankle is presented to evaluate the potential usefulness of the framework. Lifetime user satisfaction for static and dynamic design strategies are compared over simulated user preferences under a number of conditions. Results suggest RL-based strategies outperform static strategies for cases with dynamic user preferences despite significantly less initial information. Within RL methods, upper-confidence bound policies led to higher user satisfaction on average. This study suggests that further investigation into RL-based design strategies is warranted for situations with possibly dynamic preferences.
Numerical and Experimental Bifurcation Analysis of Trailers
Authors: Horvath Hanna Zs. , Takacs Denes 
Published: November 2020

Abstract
A 4-DoF spatial mechanical model of trailers is used to analyze the snaking, rocking and roll-over motions. The derivation of the governing equations is presented. The non-smooth characteristics of the tire forces are taken into account together with other geometrical non-linearities. Beyond the linear stability analysis the nonlinear vibrations are investigated via numerical continuation and simulations. Linear stability charts and bifurcation diagrams are constructed to identify the parameter ranges, where large amplitude vibration can occur. The domains of the snaking and the rocking motion are detected. Numerical simulations verify the existence of periodic solutions predicted by numerical bifurcation analysis. A small scale experimental rig is presented and the nonlinear vibration of the trailer is investigated.
Measuring Dielectric Properties of Ceramic Powders at Microwave Frequencies for Material Processing Applications
Authors: Graber B. D. , Iliopoulos A. P. , Michopoulos J. G. , Steuben J. C. , Birnbaum A. J. , Fischer R. P. , Johnson L. A. , Bernhardt P. A. , Coombs J. M. , Gorzkowski E. P. , Patterson E. A. 
Published: November 2020

Abstract
Ceramic powders are commonly used as precursors for several ceramic part manufacturing processes. Their dielectric characterization is necessary for all the cases where electromagnetic radiation is used to induce heating. In support of such activities at the U.S. Naval Research Laboratory, the present work introduces a technique for measuring the complex dielectric constants of ceramic powders at microwave frequencies. The data produced by this technique is critical for the proper modeling of ceramic powder microwave absorption and will assist in ongoing research into volumetric microwave sintering. This technique involves a transmission line measurement using a network analyzer and waveguide setup. Dielectric parameters are then extracted from these measurements using two established methods. Complex relative permittivity measurements are presented for ceramic powders ofyttria stabilized zirconia (YSZ), barium titanate (BaTiO3), zinc oxide (ZnO), and titanium dioxide (TiO2) as well as a method for containing the sample shape during measurement. Experiments were carried out between 25 and 40GHz; in the Ka microwave band. Experimental results suggest that the dielectric constant (ε′) of these powders are similar to those of bulk. Results are compared to lower frequency reference data showing reasonable agreement.
Knee Prostheses Reverse Engineering: A Preliminary Investigation
Authors: Rossoni Marco , Regazzoni Daniele , Vitali Andrea , Colombo Giorgio , Spandre Luca , De Caro Francesca 
Published: November 2020

Abstract
Total Knee Arthroplasty is one of the most commonly performed orthopedic procedures and it is expected to grow in the next future. In the last past years, computer-assisted procedures represent one of the trends that are transforming the way of practicing medicine. Cornering the Total Knee Arthroplasty, digital models of the joints have been used to carry out simulation of their kinematics and mechanical performance. Whilst for the 3D digital reconstruction of the patient geometry several studies have been conducted, an approximated geometry of the prosthesis has been several times employed, with undeniable consequences on the final results. This paper aims at comparing two non-contact reverse engineering technologies to acquire the shape of femoral components employed for total knee arthroplasty. A high-level device (Konika Minolta Vivid 9i) and a mid-low cost laser (NextEngine) has been compared. For the comparison, a systematic procedure of acquisition and elaboration of the results has been adopted in order to have as unbiased as possible results. The procedure involves the use of the proprietary software of the scanners for the elaboration of the raw data and the meshing procedure has been kept the same for all the models. Since the as-is acquired mesh is of high-resolution, a decimation procedure has been carried out in order to make the 3D models lighter and easier to be handled. Once the decimation procedure has been evaluated comparing the original and the simplified models to one another, the digitalized models have been compared with the measurements taken from a coordinate measuring machines. As a preliminary result, the two lasers seem to be adequate to accomplish the reverse engineering process as required by this application. Of course, the mid-low cost laser would be preferable whether the performance will be confirmed to be (statistically) equal.
A Study of Human Balance and Coordination Using a Head Mounted Display
Authors: Gracia De Luna Daniel , Tijernia Roel , Butler Alley , Tomai Emmett , Timmer Douglas , Caruntu Dumitru 
Published: November 2020

Abstract
This paper reports on an experiment in human subject balance and coordination using a HTC Vive head mounted display to create a virtual environment. For the experiment, 30 male human subjects of college age and 30 female subjects of college age were asked to navigate along a clear path in a virtual world using a controller with their dominant hand and asked to balance a virtual ball on a virtual plate using the other controller in the non-dominant hand. The test subjects moved along a clearly marked path, with three surprise obstacles occurring: a large rock landing near the path, and explosion near the path, and a flock of birds coming across the path. Data included 6 degree of freedom trajectories for the head, and both hands, as well as data gathered by the computer system on ball location and velocity, plate location and velocity and ball status. Likert scale questionnaires were answered by the test subjects relative to video game experience, sense of presence, and ease of managing the ball movement. Statistics showed that the male students dropped the ball less frequently at p = 0.0254 and p = 0.0036. In contrast, female students were aware of their performance with correlation levels of 0.632 and 0.588.
Optimal Product Family Architecture Design and Commonality Decision for Sustainability and Intellectual Property Protection
Authors: Kim Jinju , Saidani Michael , Kim Harrison M. 
Published: November 2020

Abstract
With the rapid development of new technology and the growing global competition in industry, it is essential for companies to protect their sensitive product designs and technologies. To ensure that their systems are not exploited by third-party competitors or remanufacturers, original equipment manufacturers often apply physical attributes and/or reduce commonality within a product family to prevent easy reusing and recovering. Yet, these design strategies are key barriers to the sustainable recovery and recycling of products. To address these trade-offs, this paper proposes a stepwise methodology to identify the sustainable optimal product family architecture design while protecting intellectual property on sensitive parts or modules. The developed approach notably allows the selection of suitable and sustainable candidates to share among products, taking into account the cost-benefit of commonality within the product family. As such, it can be used as a decision support tool to help product designers identify appropriate product family architecture design and find candidates that can be shared within a product family by considering both sustainability and security parameters.
Variational Principles for Non-Material Systems Within an Arbitrary Lagrangian Eulerian Description of Motion
Authors: Pennisi Giuseppe , Bauchau Olivier 
Published: November 2020

Abstract
Dynamics of axially moving continua, such as beams, cables and strings, can be modeled by use of an Arbitrary La-grangian Eulerian (ALE) approach. Within a Finite Element framework, an ALE element is indeed a non-material system, i.e. a mass flow occurs at its boundaries. This article presents the dynamic description of such systems and highlights the peculiarities that arise when applying standard mechanical principles to non-material systems. Starting from D’Alembert’s principle, Hamilton’s principle and Lagrange’s equations for a non-material system are derived and the significance of the additional transport terms discussed. Subsequently, the numerical example of a length-changing beam is illustrated. Energetic considerations show the complex dynamic behavior non-material systems might exhibit.
Parallelized Additive Manufacturing of Variably Partitioned Volumes for Large Scale 3D Printing With Localized Quality
Authors: Dinar Mahmoud 
Published: November 2020

Abstract
Despite the growing application of additive manufacturing (AM) in fabricating complex designs, most machines suffer from small working envelopes and slow processing speeds. One workaround to the problem of small throughput in AM is to partition the volume of a desired object and fabricate sub-volumes in parallel. Prior related work has focused on two problems. One is the geometric division problem, disregarding AM benefits and challenges in determining partitions. Others attempt to install multiple AM processing heads on the same machine, ensuring seamless bonding between deposited material from different heads while avoiding interference among them. A missed opportunity lies in deploying many independent machines simultaneously while considering benefits and limitations of AM. To that end, objects too large to be fabricated on one machine, are divided primarily into cubes that exploit benefits of AM. Specifically, the cubes are hollowed out in the direction of printing to reduce weight while avoiding the need for support structure, and depending on load conditions, packed in different orientations to mitigate material anisotropy.
A Consumer Dissatisfaction Model Linking Dynamic Pricing With Shifted Product-Use in Residential Electricity Markets
Authors: Dunbar Samuel , Ferguson Scott 
Published: November 2020

Abstract
Demand Response (DR) is the implementation of a specific strategy or set of strategies, with the goal of altering consumer energy demand, such that some system level objectives are improved. These strategies typically include dynamic pricing, direct load control, policy implementation, or other financial incentives. DR will become a crucial tool for managing growing global energy demand in conjunction with higher penetration rates of intermittent renewable energy resources. Effective implementation of a DR strategy requires a realistic understanding of how consumers will respond to that strategy and how they will be affected by it. Here, a product-based decision model for residential consumers, that links consumer decisions directly to product-use, is revisited and adapted from a continuous time formulation to discrete time. The relationship between financial incentives, consumer preferences, and demand flexibility at the population level is then quantified. The model is used for exploring the tradeoffs between typical objectives for a dynamic pricing residential DR program and evaluating the characteristics of well-performing pricing solutions.
Neural Network Based Transfer Learning of Manipulator Inverse Displacement Analysis
Authors: Tang Houcheng , Notash Leila 
Published: November 2020

Abstract
In this paper, a neural network based transfer learning approach of inverse displacement analysis of robot manipulators is studied. Neural networks with different structures are applied utilizing data from different configurations of a manipulator for training purposes. Then the transfer learning was conducted between manipulators with different geometric layouts. The training is performed on both the neural networks with pretrained initial parameters and the neural networks with random initialization. To investigate the rate of convergence of data fitting comprehensively, different values of performance targets are defined. The computing epochs and performance measures are compared. It is presented that, depending on the structure of neural network, the proposed transfer learning can accelerate the training process and achieve higher accuracy. For different datasets, the transfer learning approach improves their performance differently.
Reconstruction of Ground Reaction Force Data Using Lyapunov Floquet Theory and Invariant Manifold Theory
Authors: Bhat Sandesh G. , Sugar Thomas G. , Redkar Sangram 
Published: November 2020

Abstract
Ground Reaction Force (GRF) is an essential gait parameter. GRF analysis provides important information regarding various aspects of gait. GRF has been traditionally measured using bulky force plates within lab environments. There exist portable force sensing units, but their accuracy is wanting. Estimation of GRF has applications in remote wearable systems for rehabilitation, to measure performance in athletes, etc. This article explores a novel method for GRF estimation using the Lyapunov-Floquet (LF) and invariant manifold theory. We assume human gait to be a periodic motion without external forcing. Using time delayed embedding, a reduced order system can be reconstructed from the vertical GRF data. LF theory can be applied to perform system identification via Floquet Transition Matrix and the Lyapunov Exponents. A Conformal Map was generated using the Lyapunov Floquet Transformation that maps the original time periodic system on a linear Single Degree of Freedom (SDoF) oscillator. The response of the oscillator system can be calculated numerically and then remapped back to the original domain to get GRF time evolution. As an example, the GRF data from an optical motion capture system for two subjects was used to construct the reduced order model and system identification. A comparison between the original system and its reduced order approximation showed good correspondence.
From Information to Ideas: How Designers Structure Information to Support Idea Generation
Authors: Damen Nicole B. , Toh Christine A. 
Published: November 2020

Abstract
Design can be seen as a series of decisions that are informed by information that the designer has gathered from the environment and transformed into actionable knowledge. The sheer volume and variety of available information compels designers to impose structure upon the desired information, which in turn may affect subsequent design activities. To better understand how information may inform design decisions, this study investigates the relationship between designers’ information organization behaviors and their generated ideas by recruiting eight professionals (four from software design and four from graphic design) for individual 3-hour design sessions. They were asked to generate ideas for a design problem (reducing pedestrian accidents in Nebraska) using the provided information. Results reveal that designers structured the information in three different ways (Clusters, Relations, and Nests), and both designer background and organizational strategy display different roles in the features generated in their ideas.
Six-Bar Linkages With Compliant Mechanisms for an Adaptive Robot
Authors: Pieber Michael , Gerstmayr Johannes 
Published: November 2020

Abstract
Programmable structures are formed by autonomous and adaptive triangular cells. However, they are composed of a large number of parts, specifically bearings, which make them laborious to manufacture and expensive. An essential part of these programmable structures are six-bar linkages, which allow to build cells that can preserve the underlying geometry of a triangular mesh. A major improvement, which is the main part of this paper, is to replace the joints of the six-bar-linkage by a compliant mechanism, which allows to manufacture them as one 3D printable part. A multibody system formulation is setup with the model of the compliant mechanisms, treating every joint either ideal or compliant with the given stiffness parameters. The multi-body formulation furthermore allows to include friction as well as an actuator model in a straight-forward manner. The overall stiffness parameter of the real system is then identified from a comparison with an experimental setup of a real compliant triangular cell. Finally, the model is used to show the deviations of a medium-scaled programmable structure with respect to the idealized behavior. The present paper marks a relevant step towards the realization of larger programmable structures as well as the development of 3D programmable structures.
Deployable Convex Generalized Cylindrical Surfaces Using Torsional Joints
Authors: Nelson Todd G. , Baldelomar Pinto Luis M. , Bruton Jared T. , Deng Zhicheng , Nelson Curtis G. , Howell Larry L. 
Published: November 2020

Abstract
The ability to deploy a planar surface to a desired convex profile can enhance foldable or morphing airfoils, deployable antennae and reflectors, and other applications where a specific profile geometry is desired from a planar sheet. A model using a system of rigid links joined by torsional springs of tailorable stiffness is employed to create an approximate curved surface when two opposing tip loads are applied. The physical implementation of the model uses compliant torsion bars as the torsion springs. A multidimensional optimization algorithm is presented to minimize the error from the rigid-link approximation and account for additional manufacturing and stress considerations in the torsion bars. A proof is presented to show that equal torsion spring spacing along the horizontal axis of deployed parabolic profiles will result in minimizing the area between the model’s rigid-link approximation and smooth curve. The model is demonstrated through the physical construction of a deployable airfoil surface and a metallic deployable parabolic reflector.
Thermo-Mechanical Coupling Characteristics of Dry Clutch Under Different Automotive Starting Modes
Authors: Wu Guangqiang , Li Pingyang 
Published: November 2020

Abstract
Both system dynamics simulation and numerical analysis have been conducted to study the effect of different automotive starting modes on the clutch thermo-mechanical coupling characteristics. Based on the six-degree-of-freedom dynamic model of the automotive driveline, the system dynamic responses were obtained under four different starting modes that are determined by the changes of pressure between the friction plate and pressure plate. According to the results of dynamic responses, the transient thermal analysis and thermo-mechanical coupling analysis of the clutch friction pair were performed using the finite element method assuming that the car is driving on the congested roads. The results show that as the starting time increases, the thermal-mechanical coupling characteristics of the clutch become sever, as the temperature and stress levels of the friction pair show a trend of slow and then rapid rise. Therefore, taking into account the requirements of both well starting riding comfort and clutch working conditions, it is recommended that the driver controls the starting time within a certain range when operating the clutch pedal.
The Presence of Culture in Student Designer Perceptions When Making Design Requirements: A Pilot Study
Authors: Agyemang Malena , Turner Cameron J. 
Published: November 2020

Abstract
Unaddressed cultural elements have prevented the adoption and diffusion of many humanitarian engineering and global development efforts. Design requirements act as the link between the designer and the target users. This pilot study looks at the perceptions of student designers when making design requirements, to understand what aspects of target user culture designers consider when making design requirements. This study also looks at how a formal method that encourages designers to use the culture of the target user to assess their design requirements affects the designers’ considerations when generating design requirements as well as the design requirements they generate. A quasi-experimental case study methodology was used for this study. Using a control group and an experimental group, student perceptions and design requirements were collected and compared to uncover the cultural considerations when making design requirements, their design requirements, and the effects on their cultural considerations and design requirements post-intervention. The study showed that the use of the formal method increased the designer’s consideration for target user culture when generating design requirements. However, the findings do not suggest that the intervention method alone altered the designer’s considerations and design requirements. This study acts as a pilot study to understand experimental design limitations that will be addressed in a larger study.