bluuebunny/crossref_metadata_2025 huggingface dataset:
Retractable Anti-Buckling Support Systems for Flexible Medical Devices
Authors: Sargent Brandon S. , Magleby Spencer P. , Jensen Brian D. , Howell Larry L.
Published: November 2018

This work presents two novel support systems used to help mitigate flexible device buckling during insertion such as the insertion of medical device into the body. These systems are collapsible to accommodate the changing length of the flexible device as it is inserted. They use tension in wires or geometry to provide systems with lateral stiffness used to support the device. Through modeling, the performance of these systems can be predicted and they can be designed to a desired performance. This was validated in the geometry-based support system. They provide systems with small operating volumes and part counts.
Operational Space Formulation Under Joint Constraints
Authors: Muñoz Osorio Juan D. , Fiore Mario D. , Allmendinger Felix
Published: November 2018

In this paper, the problem of including hard constraints in the stack of tasks for torque-controlled serial manipulators is treated. The classic potential field approach is studied and a novel implementation of it is proposed. This implementation reduces the kinetic energy in the proximity of joint limits. Furthermore, a novel approach is proposed in order to include not only joint positions but also joint velocities and acceleration limits. This approach is called “Saturation in Joint Space” (SJS). The algorithm proceeds by creating a task with the highest priority in a stack of tasks scheme. This high priority task saturates the acceleration of the joints that would exceed their motion limits. The methods are tested and compared in simulation for the KUKA LBR iiwa. The SJS approach presents smoother behaviour near to the joint limits, while a Cartesian trajectory is traced. Experiments are performed to test the efficiency of this method in a real environment and under interaction with a human. The on-line saturation of the joint acceleration generates a friendly behaviour with the human even when he pushes the robot towards its limits.
Automating Structural Modeling of Composites Enriched by X-Ray Micro-Tomography and Digital Imaging Data
Authors: Iliopoulos Athanasios P. , Michopoulos John G. , Steuben John C. , Birnbaum Andrew J. , Lua Jim , Karuppiah Anand , Seneviratne Waruna , Saathoff Caleb
Published: November 2018

The manufacturing processes of Fiber Reinforced Polymers (FRPs) as composite materials are frequently prone to the creation of various types of undesired morphologies and defects. These can include layer waviness, inclusions, and voids. Structural modeling for Finite Element Analysis (FEA) of structures including such morphologies and defects has not been practically realizable until recent developments in X-ray microtomography enabled the detection of such defects in a nondestructive manner. In the present work we present our initial steps toward the FEA modeling of FRP composite structures that leverage utilization of X-ray and regular digital imaging data as well as semi-automated methods for generating appropriate FEA models. Emphasis is given in defining waviness-driven curvilinear coordinate systems, defect identification and integration of both waviness and defects to FEA analysis including a planestrain application of a curved composite bracket under four-point bending conditions.
The Ends or the Means? Understanding How Students Use Causal and Effectual Information During Design Activities
Authors: Abid Ammar , Shi Wenyu , Toh Christine A.
Published: November 2018

Although prior research has shown that information utilized during conceptual design plays a vital role in product success, there is no comprehensive framework for characterizing the types of knowledge used by designers, or the impact of information types on the development of successful ideas. As part of an ongoing effort to develop a Typological Framework of Design Information, this study focuses on understanding the impact of design reasoning using one dimension of information, effectual or causal information. Effectual reasoning refers to setting goals that are driven by the availability of resources that are available to the designer, which is in contrast with causal reasoning, which relies taking actions to achieve a predetermined goal by any means necessary. Since research on effectual and causal information in engineering design is relatively sparse, a controlled pilot study was conducted where students interacted with a web interface and addressed a design problem. Detailed observations of participants’ interactions with the design information and the creativity of design outcomes was investigated. These findings provide insights into the role that effectual information plays in design reasoning and contribute to an emerging Typological Framework of Design Information.
Question-by-Question Interrater Analysis and Suggestions for Improvements of a Functional Model Scoring Rubric
Authors: Murphy Alexander R. , Nelson Jacob T. , Bohm Matt R. , Nagel Robert L. , Linsey Julie S.
Published: November 2018

Functional modeling is a tool used for system abstraction. By divorcing system function from component structure, functional modeling allows designers to more easily identify design opportunities and compartmentalize product functions, which can lead to innovation during the ideation process. In this paper, we examine the reliability of a rubric used to evaluate student-generated functional models by comparing interrater reliabilities on a question-by-question basis from a previous study where an examination of the reliability of each question was not assessed. We then suggest changes to the rubric in order to improve the rubric’s overall interrater reliability as well as its question-by-question interrater reliability. These rubric alterations include clarification of vague language, inclusion of examples and counter examples, and a procedure for handling nonexistent functional components as opposed to incorrect or “nonsensical” functional components. This work is in contribution to the ongoing development of this functional modeling rubric as an education instrument. As functional modeling becomes more widely accepted in the design community and in engineering curricula, it is important to have a validated evaluation metric with which to assess student-generated functional models.
When Are Designers Willing to Take Risks? How Concept Creativity and Prototype Fidelity Influence Perceived Risk
Authors: Starkey Elizabeth M. , Menold Jessica , Miller Scarlett R.
Published: November 2018

Building prototypes is an important part of the concept selection phase of the design process, where fuzzy ideas get represented to support communication and decision making. However, previous studies have shown that prototypes generate different levels of user feedback based on their fidelity and aesthetics. Furthermore, prior research on concept selection has shown that individual risk attitude effects how individuals select ideas, as creative ideas are perceived to be riskier in comparison to less creative ideas. While the role of risk has been investigated in concept selection, there is lack of research on how risk is related to the selection of prototypes at various levels of fidelity. Thus, the purpose of this study was to investigate the impact of prototype fidelity, concept creativity, and risk aversion, on perceived riskiness and concept selection through a between-subjects study with 72 engineering students. The results revealed that there was a “goldilocks” effect in which students choose concepts with “just the right amount” of novelty, not too much and not too little, as long as quality was adequate. In addition, the prototype fidelity of a concept had an interaction with uniqueness, indicating that unique concepts are more likely to be perceived as less risky if presented at higher levels of fidelity.
Control of Shared Energy Storage Assets Within Building Clusters Using Reinforcement Learning
Authors: Odonkor Philip , Lewis Kemper
Published: November 2018

This work leverages the current state of the art in reinforcement learning for continuous control, the Deep Deterministic Policy Gradient (DDPG) algorithm, towards the optimal 24-hour dispatch of shared energy assets within building clusters. The modeled DDPG agent interacts with a battery environment, designed to emulate a shared battery system. The aim here is to not only learn an efficient charged/discharged policy, but to also address the continuous domain question of how much energy should be charged or discharged. Experimentally, we examine the impact of the learned dispatch strategy towards minimizing demand peaks within the building cluster. Our results show that across the variety of building cluster combinations studied, the algorithm is able to learn and exploit energy arbitrage, tailoring it into battery dispatch strategies for peak demand shifting.
Integrative Control and Design Framework for an Actively Variable Twist Wind Turbine Blade to Increase Efficiency
Authors: Nejadkhaki Hamid Khakpour , Hall John F.
Published: November 2018

A methodology for the design and control of a variable twist wind turbine blade is presented. The blade is, modular, flexible, and additively manufactured (AM). The AM capabilities have the potential to create a flexible blade with a low torsional-to-longitudinal-stiffness ratio. This enables new design and control capabilities that could be applied to the twist angle distribution. The variable twist distribution can increase the aerodynamic efficiency during Region 2 operation. The suggested blade design includes a rigid spar and flexible AM segments that form the surrounding shells. The stiffness of each segment and the actuator placement define the twist distribution. These values are used to find the optimum free shape for the blade. Given the optimum twist distributions, actuator placement, and free shape, the required amount of actuation could be determined. The proposed design process first determines the twist distribution that maximizes the aerodynamic efficiency in Region 2. A mechanical design algorithm subsequently locates a series of actuators and defines the stiffness ratio between the blade segments. The free shape twist distribution is selected in the next step. It is chosen to minimize the amount of actuation energy required to shape the twist distribution as it changes with Region 2 wind speed. Wind profiles of 20 different sites, gathered over a three-year period, are used to get the free shape. A control framework is then developed to set the twist distribution in relation to wind speed. A case study is performed to demonstrate the suggested procedure. The aerodynamic results show up to 3.8 and 3.3% increase in the efficiency at cut-in and rated speeds, respectively. The cumulative produced energy within three years, improved by up to 1.7%. The mechanical design suggests that the required twist distribution could be achieved by five actuators. Finally, the optimum free shape is selected based on the simulations for the studied sites.
Novel 4-DOF SCARA Parallel Robot With Cylindrical Workspace
Authors: Stepanenko Oleksandr , Bonev Ilian A.
Published: November 2018

In this paper, we present a novel 4-DOF SCARA parallel robot. The 2-DOF portion of the novel robot has been proposed before and consists of an end-effector connected to the base through two legs of type RRR and one passive constraining leg of type RP, where all the base-mounted revolute joints are coaxial. Contrary to SCARA robots based on the four-bar mechanism (RRRRR), the novel robot has a fully cylindrical workspace with no voids or parallel singularities in it. The novel robot has essentially the same workspace as that of a similarly sized ceiling-mounted SCARA serial robot (RR) with links of equal length. However, the proposed robot has the advantage of having all motors mounted on the base. We present the 2-DOF portion of the robot, its kinematic analysis, and its optimal design, and finally propose a mechanism design for the 4-DOF SCARA parallel robot.
Finding Better Local Optima in Topology Optimization via Tunneling
Authors: Zhang Shanglong , Norato Julián A.
Published: November 2018

Topology optimization problems are typically non-convex, and as such, multiple local minima exist. Depending on the initial design, the type of optimization algorithm and the optimization parameters, gradient-based optimizers converge to one of those minima. Unfortunately, these minima can be highly suboptimal, particularly when the structural response is very non-linear or when multiple constraints are present. This issue is more pronounced in the topology optimization of geometric primitives, because the design representation is more compact and restricted than in free-form topology optimization. In this paper, we investigate the use of tunneling in topology optimization to move from a poor local minimum to a better one. The tunneling method used in this work is a gradient-based deterministic method that finds a better minimum than the previous one in a sequential manner. We demonstrate this approach via numerical examples and show that the coupling of the tunneling method with topology optimization leads to better designs.
Kinematic and Workspace Modelling of a 6-PUS Parallel Mechanism
Authors: Landuré Jérôme , Gosselin Clément
Published: November 2018

This article presents the kinematic analysis of a six-degree-of-freedom six-legged parallel mechanism of the 6-PUS architecture. The inverse kinematic problem is recalled and the Jacobian matrices are derived. Then, an algorithm for the geometric determination of the workspace is presented, which yields a very fast and accurate description of the workspace of the mechanism. Singular boundaries and a transmission ratio index are then introduced and studied for a set of architectural parameters. The proposed analysis yields conceptual architectures whose properties can be adjusted to fit given applications.
Patterned Carbon Nanotube Growth on Stainless Steel
Authors: Prawitt Daniel G. , Porter Danni , Jensen Brian D.
Published: November 2018

This paper presents, for the first time, the process of growing a pattern of carbon nanotubes (CNT(s)) on 316L stainless steel. The data presented is preliminary and requires further investigation to detail the growth behaviors of CNTs on stainless steel in regards to producing a pattern. However, this article presents the viability of producing a pattern on a stainless steel surface that can be used in bio-surfacing and electronic applications, among others. The results show that producing a CNT pattern on stainless steel can be achieved in a similar manner to that of producing a CNT pattern on a silicon wafer, with some vital differences in the photolithography and growth processes. The results also show that long CNT growth can lead to partial overgrowth of the pattern.
Optimization of the Bicycle Weave and Wobble Modes
Authors: Roa Sergio , Doria Alberto , Muñoz Luis
Published: November 2018

Stability of bicycles has been studied by using models that assume both a rider with hands-off and hands-on the handlebars. Some authors have presented a general comparison between the behavior of the modes of vibration which affect stability in the two configurations; nonetheless, a systematic analysis of the influence of several parameters on each configuration has not been addressed. In addition, the concept of self-stability range has been used as a stability indicator especially when analyzing a rider’s hands-off situation. In contrast, in this paper, the stability area concept is used as a stability index given that it provides more information about the vibration modes in a broader speed range. Therefore, this paper has two major aims. First, the different influence on stability indexes of geometrical, compliance and tire parameters of road racing bicycles is analyzed using hands-off and hands-on models previously published in the literature. Numerical results show that some parameters have different effects on the stability of weave and wobble modes in hands-off and hands-on conditions. Second, a trade-off between the stability behavior of weave and wobble modes is found when using the hands-on model. Therefore, a multi-objective optimization problem for maximizing the stability of both modes is addressed. A Pareto front of the stability of weave and wobble modes is found that serves to analyze the stability trade-off.
The Dynamics of Large Systems of Globally Coupled, Mistuned Electromechanical Resonators
Authors: Pyles Conor S. , Bajaj Nikhil , Rhoads Jeffrey F. , Weinstein Dana , Quinn D. Dane
Published: November 2018

While the study of coupled resonant systems is a topic of significant research interest, comparatively little work has been done to study the dynamics of coupled electromechanical systems with many degrees of freedom containing features such as element-level mistuning. In this work we consider the dynamics of a system consisting of a large (N = 16) array of globally coupled, mistuned electromechanical resonators. An analytical and experimental framework is developed to enable the study of emergent behaviors in this system. A number of behaviors are identified, such as the appearance of additional resonance frequencies that are common to all of the resonators in the array. These behaviors are seen in both the analytical model and physical system and are dependent on the global properties of the system, such as the distribution of the parameters of the resonators and the strength of the coupling between the array’s constituent elements.
Dynamic Modeling and Stability Analysis of a Dual-Rotor Wind Turbine
Authors: Filsoof Oliver T. , Hansen Morten H. , Yde Anders , Zhang Xuping
Published: November 2018

Various modal analysis methods are available for single-rotor wind turbines, but there is no report and guidance on the modal property analysis of multi-rotor wind turbines. This paper presents a dynamic modeling method for the modal response analysis of a wind turbine with two three-bladed isotropic rotors. The equations of motion are derived using Lagrange’s equations and are further linearized at a steady-state equilibrium. To avoid using Floquet Theory to remove the periodic coefficients, multi-blade coordinates are utilized. Comparison between the numerical simulations and a high-fidelity model in HAWC2 shows agreements in terms of modal frequencies. The results shows that the whirling modes splits into symmetric and asymmetric rotor modes.
Influence of the Subtended Angle on the Behavior of Folded Tape Springs
Authors: de Jong Marinus G. , van de Sande Werner W. P. J. , Herder Just L.
Published: November 2018

Tape springs are thin-walled structures with zero longitudinal and constant transverse curvature. Folding them twice and connecting both ends creates a tape loop which acts as a linear guide. When using a tape spring with a non-constant cross-section, a force generator can be created. At this time there is insufficient understanding of the influence of the tape spring’s cross-section on its behavior. This study investigates the influence of the subtended angle on the tape spring’s behavior, especially the energy distribution and the fold radius.

A tape spring is once folded in a finite element model. By performing a curvature analysis of this folded geometry, the different regions within a tape spring are identified. This information is used to identify the amount of strain energy of each region. Finally, the fold radius and fold angle are determined by analyzing the geometry of the bent region.

The analysis showed that the energy within the transition regions cannot be neglected. The energy within these regions as ratio of the total energy and the length of the transition regions both increase with the subtended angle. It is also shown that the fold radius is not constant when the subtended angle is small.

Therefore, when designing a force generator using tape loops, the energy within the transition regions should be taken into account. The subtended angle should not be small to ensure a constant radius.
Adapting the FBS Model of Designing for Usage-Driven Innovation Processes
Authors: Yannou Bernard , Cluzel François , Lamé Guillaume
Published: November 2018

There has been rising interest in confronting formal models of design with practical design methods, in order to understand better both and to explore how they can improve each other. In this article, we try to map the Radical Innovation Design (RID) methodology in Gero’s Function-Behavior-Structure (FBS) framework. We encounter difficulties in doing so, and propose new constructs extending the FBS framework to account for some processes in RID. For instance, FBS is extended to describe the early stages of RID, where usages are analyzed to identify the appropriate situations and problems on which to innovate. We present a short practical case study to illustrate the relevance of these concepts. Our findings join those of others who have investigated the use of FBS to illustrate innovative projects, where requirements are unclear. We propose perspectives for future research, notably pursuing this work with the situated FBS framework.
Social Impact in Product Design: An Exploration of Current Industry Practices
Authors: Pack Andrew T. , Phipps Emma Rose , Mattson Christopher A. , Dahlin Eric C.
Published: November 2018

Though academic research for identifying and considering the social impact of products is emerging, the actual use of these processes in industry is undeclared in the literature. The gap between academic research and the industry adoption of these theories and methodologies can have real consequences. This paper explores current practices in industry that design engineers use to consider the social impact of products during the customer use stage. 30 people from nineteen different companies were interviewed to discover what disconnects exist between academia and industry when considering a product’s social impact. Although social impact assessments (SIA) and social life cycle assessments (SLCA) are two of the most common evaluative processes discussed in the literature, not a single company interviewed used either of these processes despite affirming that they do consider social impact in product design. Predictive processes were discussed by the respondents that tended to be developed within the company and often related to government regulations.
Evaluation and Experimental Validation of Efficient Simulation Models for Optimization of an Electrical Formula Car
Authors: Schmitt Alexander , Grossert Helge , Seifried Robert
Published: November 2018

This paper presents two different ways of modeling a road vehicle for general vehicle dynamics investigation and especially to optimize the suspension geometry. Therefore a numerically highly efficient model is sought such that it can be used later in gradient-based optimization of the suspension geometry. Based on a formula style vehicle with double wishbone suspension setup, a vehicle model based on ODE-formulation using a set of minimal coordinates is built up. The kinematic loops occurring in the double wishbone suspension setup are resolved analytically to a set of independent coordinates. A second vehicle model based on a redundant coordinate formulation is used to compare the efficiency and accuracy. The performance is evaluated and the accuracy is validated with measurement data from a real formula car.
Topology, Shape, and Size Optimization of Additively Manufactured Lattice Structures Based on the Superformula
Authors: Nessi Andrea , Stanković Tino
Published: November 2018

This paper investigates the application of Superformula for structural synthesis. The focus is set on the lightweight design of parts that can be realized using discrete lattice structures. While the design domain will be obtained using the Superformula, a tetrahedral meshing technique will be applied to this domain to generate the topology of the lattice structure. The motivation for this investigation stems from the property of the Superformula to easily represent complex biological shapes, which opens a possibility to directly link a structural synthesis to a biomimetic design. Currently, numerous results are being reported showing the development of a wide range of design methods and tools that first study and then utilize the solutions and principles from the nature to solve technical problems. However, none of these methods and tools quantitatively utilizes these principles in the form of nature inspired shapes that can be controlled parametrically. The motivation for this work is also in part due to the mathematical formulation of the Superformula as a generalization of a superellipse, which, in contrast to the normal surface modeling offers a very compact and easy way to handle set of rich shape variants with promising applications in structural synthesis. The structural synthesis approach is organized as a volume minimization using Simulated Annealing (SA) to search over the topology and shape of the lattice structure. The fitness of each of candidate solutions generated by SA is determined based on the outcome of lattice member sizing for which an Interior Point based method is applied. The approach is validated with a case study involving inline skate wheel spokes.
A Method to Analyse Generic Human Motion With Low-Cost Mocap Technologies
Authors: Regazzoni Daniele , Vitali Andrea , Rizzi Caterina , Colombo Giorgio
Published: November 2018

A number of pathologies impact on the way a patient can either move or control the movements of the body. Traumas, articulation arthritis or generic orthopedic disease affect the way a person can walk or perform everyday movements; brain or spine issues can lead to a complete or partial impairment, affecting both muscular response and sensitivity. Each of these disorder shares the need of assessing patient’s condition while doing specific tests and exercises or accomplishing everyday life tasks. Moreover, also high-level sport activity may be worth using digital tools to acquire physical performances to be improved. The assessment can be done for several purpose, such as creating a custom physical rehabilitation plan, monitoring improvements or worsening over time, correcting wrong postures or bad habits and, in the sportive domain to optimize effectiveness of gestures or related energy consumption.

The paper shows the use of low-cost motion capture techniques to acquire human motion, the transfer of motion data to a digital human model and the extraction of desired information according to each specific medical or sportive purpose. We adopted the well-known and widespread Mocap technology implemented by Microsoft Kinect devices and we used iPisoft tools to perform acquisition and the preliminary data elaboration on the virtual skeleton of the patient.

The focus of the paper is on the working method that can be generalized to be adopted in any medical, rehabilitative or sportive condition in which the analysis of the motion is crucial. The acquisition scene can be optimized in terms of size and shape of the working volume and in the number and positioning of sensors. However, the most important and decisive phase consist in the knowledge acquisition and management. For each application and even for each single exercise or tasks a set of evaluation rules and thresholds must be extracted from literature or, more often, directly form experienced personnel. This operation is generally time consuming and require further iterations to be refined, but it is the core to generate an effective metric and to correctly assess patients and athletes performances. Once rules are defined, proper algorithms are defined and implemented to automatically extract only the relevant data in specific time frames to calculate performance indexes. At last, a report is generated according to final user requests and skills.
Data Driven Virtual Fixtures for Improved Shared Control
Authors: Sharp Andrew , Pryor Mitch
Published: November 2018

The Department of Energy desires to increase radioactive waste treatment automation in order to minimize radiation worker exposure. Many treatment processes require maintaining tool orientation and surface distance including inspection and dismantling tasks. This paper expands on previous shape primitive virtual fixture generation techniques to increase their expressiveness based on surface models. A robotic hardware-agnostic virtual fixture generation pipeline is constructed and tested with varied superellipsoid and supertoroid models. The pipeline converts surface models into a bi-directional graphs representing layers of offset guidance virtual fixtures. Surface models function as forbidden region virtual fixtures and are combined with the graph structure into task virtual fixtures. Results show a correlation between distance to the surface and graph layer vertices. Surface model concavity also affects the growth of offset layer vertices. Incorrect model surface normals do result in irregular graph layers and the pipeline has been tested on CAD models.
Prototyping and Simulated Analysis of Autonomous Swarm-Bots
Authors: Dhameliya Maulikkumar , Sher Sidharth , Chowdhury Souma
Published: November 2018

Teams of small (mm-to-cm scale) robots, often known as swarm-bots, can provide unique functionality owing to their small form factor, distributed sensing capabilities, resilience to disruptions and agent-loss, and likely low cost. Such swarm-bots are being increasingly touted to support various indoor surveillance, hazard detection, and search and rescue missions. This paper presents the conceptual design, fabrication, and testing of a new cm-scale wheeled swarm-bot. Simulated investigation of a simple particle-swarm-inspired approach to coordinated path planning for these swarm-bots is also presented. The swarm bot is developed around a modular platform, comprising snap-on (3D printed) structural components, a stepper-motor actuated wheel system, a Raspberry Pi computing node, a wireless radio module, a Lipo battery, and proximity sensors; all components are readily detachable, thereby allowing reconfiguration flexibility. Through three design generations, a stable prototype offering >20cm/s speed and ∼50 min endurance, was developed, assembled and tested. A virtual simulated environment is developed by combining MATLAB-based modules and a V-Rep environment, in order to simulate the coordinated operation of these swarm-bots. A 78% rate of success in completing target (light source) search missions was observed during the numerical experiments, and performance robustness was observed to improve with increasing swarm size.
A Multi-Objective Robust Optimization Approach Under Interval Uncertainty Based on Kriging and Support Vector Machine
Authors: Xie Tingli , Jiang Ping , Zhou Qi , Shu Leshi , Yang Yang
Published: November 2018

Interval uncertainty can cause uncontrollable variations in the objective and constraint values, which could seriously deteriorate the performance or even change the feasibility of the optimal solutions. Robust optimization is to obtain solutions that are optimal and minimally sensitive to uncertainty. Because large numbers of complex engineering design problems depend on time-consuming simulations, the robust optimization approaches might become computationally intractable. To address this issue, a multi-objective robust optimization approach based on Kriging and support vector machine (MORO-KS) is proposed in this paper. Firstly, the feasible domain of main problem in MORO-KS is iteratively restricted by constraint cuts formed in the subproblem. Secondly, each objective function is approximated by a Kriging model to predict the response value. Thirdly, a Support Vector Machine (SVM) model is constructed to replace all constraint functions classifying design alternatives into two categories: feasible and infeasible. A numerical example and the design optimization of a microaerial vehicle fuselage are adopted to test the proposed MORO-KS approach. Compared with the results obtained from the MORO approach based on Constraint Cuts (MORO-CC), the effectiveness and efficiency of the proposed MORO-KS approach are illustrated.
A Function-Based Scoring Method for Evaluating Student Mental Models of Systems
Authors: Nelson Jacob T. , Murphy Alexander R. , Linsey Julie S. , Bohm Matt R. , Nagel Robert L.
Published: November 2018

Mental models are loosely-defined constructs people form to reason and make predictions about their surroundings. These models are an important aspect of systems thinking for engineers, a concept that emphasizes holistic thinking when working with complex systems which is increasingly important in multiple engineering disciplines. Methods to evaluate systems thinking and mental models of systems traditionally rely on questionnaires, or detailed interactive simulations of specific processes. This work presents a method based on functional modules for evaluating student responses to an instrument based on Lawson’s bicycle problem, intended to elicit students’ mental models of two systems. Students were given a simple outline of the two systems, a hair dryer and a car radiator, and were prompted to fill and label the components required for the system to fulfil the functionality described. This was done in two sessions, once before learning functional modeling, and once after, to utilize the method of scoring to evaluate any changes in their mental models due to exposure to functional modeling. The scoring method identifies common functional modules between two systems using Module Heuristics, and then identifies students’ recognition of those modules. This allows a direct comparison of the functional similarity between the two systems identified by the students and can capture a wider variety of correct answers than simply counting the components a student provides.
Environmental Evaluation of Papercrete Based on Life Cycle Assessment
Authors: Wang Xiang , Tate Derrick , Chin Chee
Published: November 2018

Papercrete, which uses waste paper as an alternative ingredient in concrete, is regarded as one type of mix design for green concrete that provide a new opportunity for waste paper disposal. However, the specific environmental influence of introducing waste paper has not been not clarified. Therefore, to evaluate the environmental contribution and feasibility of papercrete, based on the papercrete unit, the comparison of concrete production coupled with waste paper disposal is conducted according to a Life Cycle Assessment (LCA) analysis.

The system of papercrete production discussed here covers raw material extraction to finished product. Three different treatments for waste paper combined with concrete production are considered in this study. With respect to most environmental indicators, the results indicate that papercrete by introducing waste paper achieves some environmental benefits. The major reasons that environmental indicators of papercrete improve are due to the reduction of natural resource utilization and emissions to air. In detail the environmental impacts of papercrete production acquire a remarkable improvement compared with impact of normal concrete production and the adoption of incineration disposal of waste paper. Nevertheless, the environmental benefits of papercrete production are not significant increased compared with the associated system when waste paper is collected for the manufacture of recycled paper, where most environmental indicators of papercrete production are only slightly increased.
Energy Absorption of Origami Crash Box: Numerical Simulation and Theoretical Analysis
Authors: Shi Mengyan , Ma Jiayao , Chen Yan , You Zhong
Published: November 2018

Thin-walled tubes as energy absorption devices are widely in use for their low cost and high manufacturability. Employing origami technique on a tube enables induction of a predetermined failure mode so as to improve its energy absorption efficiency. Here we study the energy absorption of a hexagonal tubular device named the origami crash box numerically and theoretically. Numerical simulations of the quasi-static axial crushing show that the pattern triggers a diamond-shaped mode, leading to a substantial increase in energy absorption and reduction in initial peak force. The effects of geometric parameters on the performance of the origami crash box are also investigated through a parametric study. Furthermore, a theoretical study on the deformation mode and energy absorption of the origami crash box is carried out, and a good match with numerical results is obtained. The origami crash box shows great promise in the design of energy absorption devices.
Systematic Framework to Apply Extraordinary User Perspective to Capture Latent Needs Among Ordinary Users
Authors: Raviselvam Sujithra , Anderson David , Hölttä-Otto Katja , Wood Kristin L.
Published: November 2018

This study aims to provide a systematic framework to apply emulation tools that could help designers to experience an extraordinary user perspective (users with some form of physical or cognitive impairment). Past studies have supported the impact of using tools that emulate a physically restricted scenario to evoke creativity and empathy among designers. The proposed approach for Empathic Experience Design (EED) guides designers to have better leverage emulation tools to understand the latent design needs from recommended extraordinary user perspectives. The framework combines the physical parameters involved while interacting with a product with the interaction activities associated with the product. This combination is used to select empathy tools that will provide an interactive experience by eliminating those parameters. By eliminating the identified parameters, participants tend to look at the design needs from the emulated extraordinary user perspectives. The framework was tested with a pilot study in which 37 participants (20 participants for Treatment Group 1 and 17 participants for Treatment Group 2) of ages 20–26 were asked to redesign a medical syringe. The extraordinary use cases implemented in this study are visual impairment, hearing impairment, low dexterity and single hand usage. The study not only tested the recommended systematic approach, but it also showed the application of an extraordinary user perspective to understand the general latent needs associated with medical devices that are less likely to be used by extraordinary users. The results are promising evidence that a simple systematic approach to implement empathic design tools could have a higher impact than an unguided instinct based approach to choose the tools. The results also show that, when applied efficiently, the approach could capture a wide variety of latent needs from potential extraordinary user perspectives’.
Physics-Based Semantic Reasoning for Function Model Decomposition
Authors: Mao Xiaoyang , Sen Chiradeep
Published: November 2018

In graph-based function models, the function verb and flow noun types are usually controlled by vocabularies of standard classes. The grammar is also controlled at different levels of formalism and contribute to reasoning. However, the text written in plain English for the names of the functions and flows is not used for formal reasoning to help with modeling or exploring the design space. This paper presents a formalism for semantic and physics-based reasoning on function model graphs, esp. to automatically decompose black box models and to generate design alternatives using those plain-English texts. A previously established formal language, which ensures that function models are consistent with physics laws, is used as a baseline. Semantic reasoning is added to use the unstructured information of the flow phrases to infer possible means of decomposing the model into a topology connecting appropriate subfunctions and to generate multiple alternative decompositions. A data structure of flow nouns, flow attributes, qualitative value scales, and qualitative physics laws is used as the data representation. An eight-step algorithm manipulates this data for reasoning. The paper shows two validation case studies to demonstrate the workings of the language.
The Effects of Mechanical Vibration on Cellular Health in Differentiated Neuroblastoma Cells
Authors: Shi Caleb , Chang Robert , Leonardi Donna
Published: November 2018

The effects of mechanical impact forces on neurological health is a critical concern, likely due to issues of traumatic brain injury (TBI) in sports and brain damage stemming from the potential of “sonic terrorism.” The quantitative analysis and evaluation of such forces on brain tissue function is very difficult. To address this issue, this research proposes a novel approach of using a cellular model subjected to mechanical vibration for analysis. Here, neuron-like differentiated neuroblastoma cells were subjected to vibration at frequencies of 20, 200, 2000, and 20000 Hz for a period of 24 hours at constant amplitude. Cell proliferation and inflammatory cytokine production, including IL-6, IL-1β, and TGF-β1, was measured as response of the cells and indicators of cellular health after vibrational treatment. Cell proliferation was found to increase after 20, 200, and 20000 Hz treatments; p<0.05) and decrease after 2000 Hz treatment (p<0.05). IL-6 production was found to decrease after 200 and 20000 Hz treatments (p<0.01) and increase after 20 and 2000 Hz treatments (p<0.01). IL-1β protein production was found to decrease after 20 Hz and increase after 200 Hz treatments (p<0.001), while TGF-β1 was found to decrease after 200 Hz treatment (p<0.001). The results suggest that cell proliferation and cytokine production serve as a sensitive measure to external impact forces applied to the cells. In addition, it is suggested that inflammatory mechanisms exhibit inhibitory “cross-talk” between IL-6 and IL-1β signaling pathways at 20 and 200 Hz. Inflammatory cytokine data suggest frequency-specific responses, which can be used not only to better understand the mechanism of vibration induced cellular damage, but also to unveil the cellular signaling processes.
Prototyping for Desirability by Design of Experiments: A Case Study of a Hardware Startup
Authors: Jensen Lasse Skovgaard , Vorting Daniel , Villadsen Andreas , Mølleskov Lasse Hylleberg , Özkil Ali Gürcan
Published: November 2018

This paper presents a study on how prototyping and ‘Design of Experiments’ principles can be applied in the early stages of product development. It is explored how four design parameters affect the perceived desirability of a physical alarm device, in development by a small start-up company. By utilizing recent advancements in the tools and platforms, available for the fabrication of prototypes, a range of physical prototypes are made. These prototypes are used to conduct 44 user tests and the results were used to establish a statistical model based on the Response Surface Methodology. The results of the model are outlined, highlighting the primary drivers of product desirability, as well as exemplifying the dynamics among the explored desirability parameters. The statistical model is tested through an experiment, which verifies the model’s ability to prescribe the perceived desirability for specific prototypes of the alarm device. The study hereby presents promising results for incorporating Design of Experiment principles in early stages of product development, and the authors encourage further studies to be conducted.
Singularities of the Typical Collaborative Robot Arm
Authors: FarzanehKaloorazi Mohammad H. , Bonev Ilian A.
Published: November 2018

In this paper, the singularities of the typical 6R collaborative robot (such as the cobots made by Universal Robots) are analytically and geometrically described. Since the axes of the last three joints in such a cobot are not concurrent, the singularities are slightly different from those of the PUMA-style manipulator. It is shown that the determinant of the Jacobian matrix of the typical cobot splits into four factors, three of which can vanish. As in the typical PUMA-style manipulator, the three vanishing factors correspond to shoulder, elbow and wrist singularities. However, in a wrist singularity, the redundant motion associated with no end-effector movement is more complex.
University Makerspaces: More Than Just Toys
Authors: Hilton Ethan C. , Smith Shaunna F. , Nagel Robert L. , Linsey Julie S. , Talley Kimberly G.
Published: November 2018

University makerspaces are growing increasingly in vogue, especially in Colleges of Engineering, but there is little empirical evidence in the literature that these spaces impact the students. Speculations have been made about these spaces creating a community of practice, improving retention, improving design skills and self-efficacy, teaching manufacturing skills, improving creativity, and providing many other benefits, but this has not been empirically documented. This paper compares student engineering design self-efficacy (i.e., confidence, motivation, expectation of success, and anxiety toward conducting engineering design) to reported usage rates from a makerspace at a large Hispanic-serving university in the Southwestern United States. Not all users of these spaces were engineering students, and as such, responses were examined through the context of student major as well as differences in gender, race/ethnicity, or first-generation college student status. Design self-efficacy is critical because when individuals have high self-efficacy for particular skills they tend to seek more opportunities to apply those skills, and show more perseverance in the face of set-backs. Thus, self-efficacy is often a good predictor of achievement. The results from one year of data at the Hispanic-serving university indicate that female and first-generation college students have significantly lower engineering design self-efficacy scores. The data also shows that being a user of the makerspace correlates to a higher confidence, motivation, and expectation of success toward engineering design. Initial data from two additional schools are also consistent with these same results. These results indicate that, for all students, regardless of race/ethnicity and/or first generation status, being a frequent user of a university-serving makerspace likely positively impacts confidence, motivation, and expectation of success toward engineering design.