bluuebunny/crossref_metadata_2025 huggingface dataset:
Automatic Extraction and Synthesis of Disassembly Information From CAD Assembly STEP File
Authors: Vyas Pushkar , Rickli Jeremy L.
Published: December 2016

Product disassembly is critical to remanufacturing, reuse, and recycling activities, which are essential reverse flows in circular economy systems. While disassembly optimization and analysis methods are well developed, many of these methods rely on basic disassembly information, i.e. a precedence matrix. Obtaining this basic disassembly information is a non-trivial task that has, in the past, required extensive manual analysis of a product assembly. This process can be significantly improved by developing methods capable of automatically extracting disassembly data from CAD/CAM assemblies. If this can be achieved accurately, efficiently, and in a timely manner, numerous disassembly optimization methods will become readily available to product designers. In pursuit of this aim, the objective of this research is to automatically extract part contact information from assembly models and determine disassembly operation feasibility. The described method uses CAD assembly STEP data as input, extracts disassembly relevant information such as, component surface contour type, Cartesian points, and normal direction of the surface, and determines the feasibility of disassembly of each component which is represented as a precedence matrix. Disassembly feasibility is evaluated using the contact function. A case assembly was tested and the precedence matrix was successfully determined for part contact disassembly constraints. Results of the research indicate that the method is capable of extracting disassembly data from CAD STEP assemblies but has critical limitations that must be overcome to be influential during design.
A Material Selection and Design Method for Multi-Constraint Compliant Mechanisms
Authors: Sessions John , Pehrson Nathan , Tolman Kyler , Erickson Jonathan , Fullwood David , Howell Larry
Published: December 2016

One of the challenges often encountered in compliant mechanism design is managing material selection given the need to meet multiple constraints. Many methods have been offered previously to systematically facilitate that decision process. However, these methods struggle to incorporate a systematic method for material selection in multi-functional compliant mechanisms. This work seeks to address this gap by generically implementing a new Ashby-based material selection and design method for compliant mechanisms with multi constraint design criteria. To help demonstrate the method, the design of an electrically conductive lamina emergent torsion (LET) joint used for a back-packable solar array is explored. The methodology described here can be used to create other compliant mechanism performance metrics to address the design of specific compliant mechanisms.
Anomaly Detection in Complex Spatiotemporal Networks Through Location Aware Geospatial Big Data Sets
Authors: Shekhar Prashant , Rai Rahul
Published: December 2016

Anomaly detection is an important problem that has been researched in several domains. Based on the available data patterns, various supervised and unsupervised anomaly detection techniques have been introduced. In this paper, a novel anomaly detection technique for location aware geospatial big dataset is outlined. Specifically, we focus on anomaly detection in spatiotemporal complex networks. The outlined technique incorporates components of anomaly quantification and decision making on spatiotemporal graphs and embeds simultaneous learning and detection procedures. The magnitude of an anomaly at each time step is quantified to signify the pattern of anomalous behavior in the spatiotemporal network. We illustrate the efficacy of the proposed method by detecting and indicating the time and location of a single or multiple anomalies in an illustrative traffic network problem. Theoretical experiments on a suite of six randomly generated traffic network problems have been performed. The performance of the proposed algorithm with tuned parameters on this random set of problem instances clearly establishes the effectiveness and applicability of the introduced solution procedure.
Understanding the Impact of Occupancy Trends in Sustainable Housing Designs
Authors: Piacenza Joseph , Mayoral Salvador , Lin Sean , Won Lauren , Grooms Xava
Published: December 2016

As sustainable building mandates become more prevalent in new commercial buildings, it is a challenge to create a broad, one-size-fits-all certification process. While designers can estimate energy usage with computation tools such as model based design, anticipating the post occupancy usage is more difficult. Understanding energy usage trends is especially complicated in university student housing buildings, where occupancy varies significantly as a function of enrollment and course scheduling. This research explores the effect of student occupancy on both predicted and actual energy usage in a LEED (Leadership in Energy and Environmental Design) Platinum certified student housing complex. A case study is presented from the California State University Fullerton (CSUF) campus, and examines diversity factor, defined as a building’s instantaneous energy usage as a percentage of the maximum allowable usage during a period of time, trends throughout the academic year. The CSUF case diversity factor is compared to the diversity factor used in predictive models for obtaining LEED certification, and the mandates that govern the models (e.g., ASHRAE 90.1). The results of the analysis show the benefits of considering post occupancy usage in sustainable building designs, and recommendations are presented for creating unique and application based computational models, early in the design process. This research has broad applications, and can extend to sustainable building design in other organizations, whose operational schedule falls outside of current prediction methods for sustainability mandates.
A Lamina-Emergent Frustum Using a Bistable Collapsible Compliant Mechanism (BCCM)
Authors: Alfattani Rami , Lusk Craig
Published: December 2016

This paper presents a new Bistable Collapsible Compliant Mechanism (BCCM) that is utilized in a Lamina-Emergent Frustum. The mechanism is based on transforming a polygon spiral into spatial frustum shape using a mechanism composed of compliant links and joints that exhibits bistable behavior. A number of mechanism types (graphs) were considered to implement the shape-morphing spiral, including 4-bar, 6-bar, and 8-bar chains. Our design requirements permitted the selection of a particular 8-bar chain as the basis for the BCCM. Bistable behavior was added to the mechanism by introducing a compliant link that functions as a compression spring as the mechanism morphs. Parametric CAD was used to perform the dimensional synthesis. The design was successfully prototyped.
Validating a Method for Turbocharging Single Cylinder Four Stroke Engines
Authors: Buchman Michael R. , Winter Amos G.
Published: December 2016

This paper presents a method for turbocharging single cylinder four stroke internal combustion engines, an experimental setup used to test this method, and the results from this experiment. A turbocharged engine has better fuel economy, cost efficiency, and power density than an equivalently sized, naturally aspirated engine. Most multi-cylinder diesel engines are turbocharged for this reason. However, due to the timing mismatch between the exhaust stroke (when the turbocharger is powered) and the intake stroke (when the engine intakes air), turbocharging is not used in commercial single cylinder engines. Single cylinder engines are ubiquitous in developing world off-grid power applications such as tractors, generators, and water pumps due to their low cost. Turbocharging these engines could give users a lower cost and more fuel efficient engine. The proposed solution is to add an air capacitor, in the form of a large volume intake manifold, between the turbocharger compressor and the engine intake to smooth out the flow.

This research builds on a previous theoretical study where the turbocharger, capacitor, and engine system were modeled an-alytically. In order to validate the theoretical model, an experimental setup was created around a single cylinder four stroke diesel engine. A typical developing world engine was chosen and was fitted with a turbocharger. A series of sensors were added to this engine to measure pressure, temperature, and power output. Our tests showed that a turbocharger and air capacitor could be successfully fitted to a single cylinder engine to increase intake air density by forty-three percent and peak power output by twenty-nine percent.
A Visual Ontological Language for Technical Standards (VOLTS)
Authors: Whitsitt Sean , Vohnout Sonia , Wilmering Timothy , Mathad Disha , Smith Eric
Published: December 2016

Research shows that failures in the standardization process often result from communication and organizational issues between those involved in the committee and the user community. This is mainly caused by two issues: first, a lack of integration of available standards development tools with communication and social interfaces; and second, to the difficulties inherent in organizing and collating information in a semantically meaningful manner. To this effect, the authors present a Visual Ontological Language for Technical Standards (VOLTS). VOLTS is a prototype environment that seeks to address the latter problem introduced above. In VOLTS, standards developers visually create standards within a network of information. VOLTS builds upon a tool developed by the National Institute of Standards and Technology (NIST) called the NIST Ontological Visualization Interface for Standards (NOVIS), which presented a novel method for visualizing the content and connections of standards, but lacked the ability to allow users to alter that information. VOLTS focuses on providing users with a process that allows for verification and validation at all stages of development. To that effect, VOLTS incorporates research done by NIST on building a Framework for Analysis Comparison, and Test of Standards (FACTS). The examples presented herein use the openly available standards World Wide Web Consortium’s (W3C) Web Ontology Language (OWL) 2 and the Data Mining Group’s (DMG) Predictive Model Markup Language (PMML) to demonstrate the VOLTS process and methodology. Future work discussed will seek to address the former problem introduced above.
Modeling the Multiphysics Wrinkling Instability of Ionic Polymer Composite Plates for Artificial Muscle Applications
Authors: Michopoulos John G. , Iliopoulos Athanasios P.
Published: December 2016

In this paper we first present the derivation of the governing equations that describe the multiphysics behavior of Ionic Polymer Composite Plates (IPMC). This is done in a manner that accounts for their non-linear large deflection deformation under the influence of mechanical, electrical, thermal and multicomponent mass transport fields. We subsequently present numerical solutions of the system of these equations via the use of the finite element method for a case of a specific rectangular plate. Emphasis is given in identifying the multiphysics based wrinkling instability behavior that manifest near the corners of these plates due to multiphysics stimuli.
Experimental Analysis of the Bending Response of Soft Gripper Fingers
Authors: Elgeneidy Khaled , Lohse Niels , Jackson Michael
Published: December 2016

In this paper a common design for soft actuators with internal pneumatic networks is analysed for the application of passively compliant soft gripper fingers, which can effectively grasp complex and delicate objects. The behaviour of a soft finger upon actuation is primarily determined through its predefined morphology. Hence, understanding the effects of key design parameters on the desired bending response is essential to design improved soft fingers. An experiment was designed to analyse the effects of two dimensionless design parameters defining the geometry of the internal pneumatic channels, on measurable parameters that describe the bending response of soft fingers as well as the generated contact forces. Soft finger samples were designed and produced based on combinations of different levels of the studied parameters, with the same outer dimensions and material. The experiment setup utilises a pneumatic control board for controlling the actuation and a vision system for measuring the bending response, which can be modified to analyse other designs of soft actuators. The results of the experiment identified the best performing soft finger design, explaining the effect of the studied factors in enhancing its desired response. The outcome of this work serves as a step towards a more structured design guideline that can be followed to create soft fingers with an enhanced and more predictable grasping behaviour.
Effect of Temperature Dependent Properties on the Applicability of the Heat Conduction Equations for Rapid Heat Deposition Applications
Authors: Michopoulos John G. , Birnbaum Andrew , Iliopoulos Athanasios P.
Published: December 2016

Despite significant efforts examining the suitability of the proper form of the heat transfer partial differential equation (PDE) as a function of the time scale of interest (e.g. seconds, picoseconds, femtoseconds, etc.), very little work has been done to investigate the millisecond-microsecond regime. This paper examines the differences between the parabolic and one of the hyber-bolic forms of the heat conduction PDE that govern the thermal energy conservation on these intermediate timescales. Emphasis is given to the types of problems where relatively fast heat flux deposition is realized. Specifically, the classical parabolic form is contrasted against the lesser known Cattaneo-Vernotte hyperbolic form. A comparative study of the behavior of these forms over various pulsed conditions are applied at the center of a rectangular plate. Further emphasis is given to the variability of the solutions subject to constant or temperature-dependent thermal properties. Additionally, two materials, Al-6061 and refractory Nb1Zr, with widely varying thermal properties, were investigated.
Implicit Slicing for Functionally Tailored Additive Manufacturing
Authors: Steuben John C. , Iliopoulos Athanasios P. , Michopoulos John G.
Published: December 2016

One crucial component of the additive manufacturing software toolchain is a class of geometric algorithms known as “slicers.” The purpose of the slicer is to compute a parametric toolpath defined at the mesoscale and associated g-code commands, which direct an additive manufacturing system to produce a physical realization of a three-dimensional input model. Existing slicing algorithms operate by application of geometric transformations upon the input geometry in order to produce the toolpath. In this paper we introduce an implicit slicing algorithm that computes mesoscale toolpaths from the level sets of heuristics-based or physics-based fields defined over the input geometry. This enables computationally efficient slicing of arbitrarily complex geometries in a straight forward fashion. The calculation of component “infill” is explored, as a process control parameter, due to its strong influence on the produced component’s functional performance. Several examples of the application of the proposed implicit slicer are presented. It is demonstrated — via proper experimentation — that the implicit slicer can produce a mesoscale structure leading to objects of superior functional performance such as greatly increased stiffness and ultimate strength without an increase of mass. We conclude with remarks regarding the strengths of the implicit approach relative to existing explicit approaches, and discuss future work required in order to extend the methodology.
Knowledge Retention and Scoring Metrics for Functional Modeling in an Engineering Design Context
Authors: Riggs Marie , Mountain Philip , Nagel Robert L. , Bohm Matt R. , Linsey Julie S.
Published: December 2016

Functional modeling as a design methodology is often covered in engineering design texts as a tool for transforming “customer speak” into “engineering speak.” There is little to no empirical data, though, that clearly demonstrates that learning functional modeling actually improves students’ engineering design skills. The overall objective of this project is to determine the impact of teaching function on engineering students’ design synthesis abilities. This paper focuses on preliminary data collected as a part of the longitudinal study. Students were asked to generate functional models of functionally similar systems at two points during an engineering design course: (1) once as a homework assignment immediately following the introduction of the topic and (2) again as a low stakes in-class activity seven weeks later. This paper will present the comparison of models created at both data points. Student models at each time point are analyzed using a validated 18-question rubric. The results provide promise that, in general, students retain their modeling ability, but there are noted characteristic differences between homework-generated functional models and those generated later in the semester during an in-class activity. These characteristics will be discussed as will potential improvements to the scoring rubric.
Topological Reconfigurations of Bennett-Based Linkages
Authors: Hsu Kuan-Lun , Ting Kwun-Lon
Published: December 2016

This paper presents the methodology of topological reconfigurations with composite Bennett linkages. A new family of diverse reconfigurable Bennett linkages is discovered. The framework is based on the parallel combination of Bennett chains. Two kinds of expansible frameworks are addressed in detail. The topological reconfigurations of Bennett-based linkage with multiple working-phases can be attained from the composite framework of the compositing Bennett chain by eliminating the revolute angle between its adjacent links. Several examples are provided not only to interpret the construction of extant ones but also to develop more complicated ones. The proposed method systematically discovers all possible permutations of number of joints and links for topological variants of the resultant linkages. The spatial linkage built based on the presented methodology may be either overconstrained or underconstrained because some of their DOFs may not follow the mobility as predicted by Chebychev-Grübler-Kutzbach criterion.
Development of Autonomous Robotic Cataract Surgery Device
Authors: Francom Matthew , Burns Clinton , Repisky Philip , Medina Benjamin , Kinney Alex , Tello Erick , Ben-Tzvi Pinhas
Published: December 2016

The current rate of incidence of cataracts is increasing faster than treatment capacity, and an autonomous robotic system is proposed to mitigate this by carrying out cataract surgeries. The robot is composed of a three actuator RPS parallel mechanism in series with an actuated rail mounted roller that moves around the eye, and is designed to perform a simplified version of the extracapsular cataract surgery procedure autonomously. The majority of the design work has been completed, and it is projected that the system will have a tool accuracy of 0.167 mm, 0.141 mm, and 0.290 mm in the x, y, and z directions, respectively. Such accuracies are within the acceptable errors of 1.77mm in the x and y directions of the horizontal plane, as well as 1.139 mm in the vertical z direction. Tracking of the tool when moving at 2 mm/s should give increments of 0.08 mm per frame, ensuring constant visual feedback. Future work will involve completing construction and testing of the device, as well as adding the capability to perform a more comprehensive surgical procedure if time allows.
Linear and Non Linear Energy Harvesting From Bridge Vibrations
Authors: Orfei Francesco , Vocca Helios , Gammaitoni Luca
Published: December 2016

In this paper we analyze the performances of three different energy harvester configurations aimed at transforming vibration energy from a vehicle transited bridge. First of all we sampled the vibrations of a highway bridge in three different positions: at the entrance, in the middle and at the exit. Then, from the sampled time series, we reproduced the vibrations in the lab and tested the different harvesting configurations: low frequency linear piezoelectric energy harvester; high frequency linear piezoelectric energy harvester; non-linear bi-stable broadband piezoelectric energy harvester. The results are presented in terms of the RMS power converted. All the harvesters were built with the same piezoelectric material: composition and size were always the same.
Assembly Based Part Design to Improve the Additive Manufacturing Productivity: Process Time, Cost and Surface Roughness
Authors: Oh Yosep , Behdad Sara
Published: December 2016

In design for assembly (DFA), minimizing part numbers is a significant guideline for product design improvement. For this reason, producing a single product regardless of its geometric complexity has been noted as one of the key advantages of additive manufacturing (AM) in the literature. This paper, however, points out that designing assembly parts also has positive influences on AM productivity. In fact, assembly designs enable AM manufacturers to reduce the build time by lowering the height of parts, to decrease the material cost by reducing the amount of support, and to improve the surface quality by deciding the proper orientations for build-up parts. For applying to AM, we propose the assembly design procedure that includes two main phases: designing assembly parts employing design guidelines and evaluating the assembly parts with a quantitative method. In the guidelines for assembly designs, there are mainly two categories: (1) basic principles for assembly designs; and (2) connection types for part assemblies. The former deals with how we separate a single product into several parts and how we make a decision about a build-up orientation in order to improve the AM productivity. The latter covers connection methods that explain how divided parts are connected into a single product again. To assess the assembly part designs quantitatively, we suggest a simple estimation model based on the digital light processing (DLP), an AM technology that results in high efficiency in terms of the build time. A numerical example is provided to show how different assembly designs are compared to select the best one with the highest AM productivity.
Numerical Procedure for Design Optimization of Wind Turbine Drivetrain Using Multibody Gear Dynamics Simulation Considering Wind Load Uncertainty
Authors: Li Huaxia , Sugiyama Hiroyuki , Cho Hyunkyoo , Choi K. K. , Gaul Nicholas J.
Published: December 2016

An accurate prediction of the service life of wind turbine drivetrains is crucial to ensure safe and reliable operation. In particular, gear teeth of the wind turbine multi-stage drivetrain experience severe cyclic rolling contact resulting from highly variable wind loads which are stochastic in nature. Thus, the failure rate of the gearbox is reported to be higher than other wind turbine components. Despite many studies on gear contact and failure analysis of wind turbine drivetrains, limited studies have been carried out regarding gear design optimization considering wind load uncertainty. For this reason, in this study, an integrated multibody gear dynamics simulation procedure for design optimization of the wind turbine drivetrain considering the wide spatiotemporal wind load uncertainty is developed. To this end, the wind load uncertainty model using the joint probability density function of the ten-minute mean wind speed and turbulence intensity, rotor blade aerodynamics, drivetrain dynamics considering the detailed gear tooth contact geometry including the profile modification, and probabilistic contact fatigue failure model are integrated for use in the gear tooth design optimization of wind turbine drivetrains to ensure the expected design life. Several numerical examples are presented to demonstrate the numerical procedure developed in this study.
Impact of Level of Detail and Information Content on Accuracy of Function Structure-Based Market Price Prediction Models
Authors: Gill Amaninder Singh , Summers Joshua D. , Turner Cameron J.
Published: December 2016

This paper explores the amount of information stored in the representational components of a function structure: vocabulary, grammar, and topology. This is done by classifying the previously developed functional composition rules into vocabulary, grammatical, and topological classes and applying them to function structures available in an external design repository. The pruned function structures of electromechanical devices are then evaluated for how accurately market values can be predicted using graph complexity connectivity method. The accuracy is inversely with amount of information and level of detail. Applying the topological rule does not significantly impact the predictive power of the models, while applying the vocabulary rules and the grammar rules reduce the accuracy of the predictions. Finally, the least predictive model set is that which had all rules applied. In this manner, the value of a representation to predict or answer questions is quantified through this research approach.
Global Sensitivity Analysis for a Bayesian Network
Authors: Li Chenzhao , Mahadevan Sankaran
Published: December 2016

In a Bayesian network, how a node of interest is affected by the observation of another node is of interest in both forward propagation and backward inference. The proposed global sensitivity analysis (GSA) for Bayesian network aims to calculate the Sobol’ sensitivity index of a node with respect to the node of interest. The desired GSA for Bayesian network confronts two challenges. First, the computation of the Sobol’ index requires a deterministic function while the Bayesian network is a stochastic model. Second, the computation of the Sobol’ index can be expensive, especially if the model inputs are correlated, which is common in a Bayesian network.

To solve the first challenge, this paper uses the auxiliary variable method to convert the path between two nodes in the Bayesian network to a deterministic function, thus making the Sobol’ index computation feasible in a Bayesian network. To solve the second challenge, this paper proposes an efficient algorithm to directly estimate the first-order Sobol’ index from Monte Carlo samples of the prior distribution of the Bayesian network, so that the proposed GSA for Bayesian network is computationally affordable. Before the updating, the proposed algorithm can predict the uncertainty reduction of the node of interest purely using the prior distribution samples, thus providing quantitative guidance for effective observation and updating.
Lifting Motions During Patient Repositioning in Novice and Experienced Nurses: A Pilot Study
Authors: Holmes Abigail , Opella Jessie , Cloutier Aimee , Yang James , DeLucia Patricia R.
Published: December 2016

According to the Bureau of Labor Statistics, in 2014, nursing and residential care facilities had the highest incidence rate of total nonfatal occupational injury cases in the U.S. Manual patient handling tasks result in high lumbar load (Jager et al., 2013), and most of work-related back disorders in nurses are related to patient transfers. The present pilot study seeks to determine if there are significant differences in the motion of experienced nurses and novice nurses while performing the same patient repositioning tasks. A motion capture experiment was conducted in a laboratory setting on 14 female nurses performing two patient repositioning tasks (moving patient toward the head of the bed; transferring patient from bed to a wheelchair). Of the nurses selected, 7 were experienced nurses (greater than 5 years of nursing experience), and 7 were novice nurses (between 0 and 2 years of nursing experience). The motion capture data were post processed using Cortex and Visual3D software. Average and maximum joint angles for the spine, knees, elbows, and shoulders for each task were compared between the novice and experienced nurses using a Wilcoxon Rank Sum test to determine whether there were significant differences in motion for the same patient repositioning tasks. Although significant differences were not found for average or maximum joint angles between the novice and experienced groups, there was a significant difference in variances between the novice and experienced groups for some angles for the wheelchair task.
Analysis and a Case Study of Model Reference Adaptive Control for Robotic Mechanisms
Authors: Zhang Dan , Wei Bin
Published: December 2016

Motion control accuracy of robotic manipulators affects the overall robotic system performance. When the end-effector grasps different payloads, the joint motion of robotic manipulators will vary depending on the different payload masses. Traditional controllers have the problem of not being able to compensate the payload variation effect. Model reference adaptive control has been proposed to address the above problem. This paper discusses the model reference adaptive control of robotic manipulators initially raised by Roberto Horowitz and its associated development by other authors. A case study for a hybrid controller, which is derived from the model reference adaptive control system, is presented. Very few recent papers can be found in the area of model reference adaptive control of robotic manipulators, and this study can provide a guideline for future research in the direction of model reference adaptive control for robotic arms.
Application of Bio-Inspired Design to Minimize Material Diversity
Authors: McCullar Katie S. , Rhodes Preston C. , Underhill S. Austin , Nagel Jacquelyn K. S.
Published: December 2016

Bio-inspired design, or biomimicry, is an approach to innovation that takes nature’s time-tested patterns, forms, functions, processes, and materials and uses them to develop engineering solutions. In this project we take inspiration from biological morphologies to develop new forms for semi-recyclable products. Biological systems exhibit multi-functionality from form, not necessarily material, which offers inspiration for product life-cycle management. The goal is to better understand the connection between form and function as found in nature to enable sustainable product design and enhance additive manufacturing processes. Through the application of bio-inspired design product recyclability is increased through minimization of material diversity while still achieving desired functions. One inspiring biological morphology that has been utilized across multiple biological kingdoms and in this research is variations in hardness and flexibility found in alternating layers that are used to provide strength, durability and protection. Another inspiring morphology considered in this research is the backbone of water-diving birds, which consists of an intricately braided spine with parallel holes along each side. These holes allow for shock absorbance and force dispersion. These multi-function forms have resulted in the redesign of a semi-recyclable product fabricated using additive manufacturing to create a product that is made from a single material yet still achieves all necessary functions. Key contributions of this research include approaches for additive manufacturing strategies such as material utilization that align with a product’s life cycle, thus increasing the recyclability of the product.
Wind Turbine Blade Damage Detection Using Various Machine Learning Algorithms
Authors: Regan Taylor , Canturk Rukiye , Slavkovsky Elizabeth , Niezrecki Christopher , Inalpolat Murat
Published: December 2016

Wind turbine blades undergo high operational loads, experience variable environmental conditions, and are susceptible to failures due to defects, fatigue, and weather induced damage. These large-scale composite structures are essentially enclosed acoustic cavities and currently have limited, if any, structural health monitoring in practice. A novel acoustics-based structural sensing and health monitoring technique is developed, requiring efficient algorithms for operational damage detection of cavity structures. This paper describes a systematic approach used in the identification of a competent machine learning algorithm as well as a set of statistical features for acoustics-based damage detection of enclosed cavities, such as wind turbine blades. Logistic regression (LR) and support vector machine (SVM) methods are identified and used with optimal feature selection for decision making using binary classification. A laboratory-scale wind turbine with hollow composite blades was built for damage detection studies. This test rig allows for testing of stationary or rotating blades (each fit with an internally located speaker and microphone), of which time and frequency domain information can be collected to establish baseline characteristics. The test rig can then be used to observe any deviations from the baseline characteristics. An external microphone attached to the tower will also be utilized to monitor blade damage while blades are internally ensonified by wireless speakers. An initial test campaign with healthy and damaged blade specimens is carried out to arrive at certain conclusions on the detectability and feature extraction capabilities required for damage detection.
Electrical Impedance Measurements of PZT Nanofiber Sensors
Authors: Galos Richard , Li Xin
Published: December 2016

Electrical Impedance Measurement of PZT Nanofiber sensors are performed and material properties including resistivity and dielectric constant are derived from the measurements. Nanofibers formed by electro-spinning with diameters ranging from 10 to 150 nm were collected and integrated into sensors using microfabrication techniques. The nanosensor impedance was extremely high at low frequencies and special matching circuitry was fabricated to detect output. The resulting impedance measurements are also compared with those of individual nanofibers that were tested using Scanning Conductive Microscopy (SCM) and Conductive AFM.
The Set-Up-Map for Automating the Positioning of Castings and Weldments in Fixtures to Ensure Completely Machined Surfaces
Authors: Kalish Nathan J. , Ramnath Satchit , Haghighi Payam , Davidson Joseph K. , Shah Jami J. , Shah Jiten V.
Published: December 2016

There is considerable geometric variability of raw castings and weldments before any machining of surfaces that assemble with other components. Consequently, considerable time often is spent identifying successful set-up adjustments at the machining fixtures for such parts in a way to ensure that every machined surface will be complete. The proposed Set-Up-Map© is a point-space subset of R6 where each of the six orthogonal coordinates correspond to one of the rigid-body displacements in three dimensional space: three translations and three rotations. Any point within the Set-Up-Map (S-Map) corresponds to a small body displacement (SBD) of the part that satisfies the condition that each feature will lie within its associated tolerance zone after machining. S-Maps are derived from previous work on Tolerance Maps© (T-Maps), which represent feature deviations allowed by a given tolerance zone. Each raw casting or weldment is scanned, and the point-cloud data fitted to individual features, to determine how much each to-be-machined (TBM) feature deviates from nominal specifications. Each local T-Map is formed from a library, then shifted to be centered on its corresponding scanned feature on each casting; it becomes a local S-Map primitive. Each of these local S-Maps is then transformed to a single global reference frame. The intersection of these S-Map primitives in the global frame gives the allowable small body displacements that satisfy the positioning requirements for all TBM features. Since T-Maps are convex objects, a half-space intersection method is used to generate an S-Map. Any point within the S-Map represents a viable small body displacement specific to the global coordinate system established on the part. In the case that as-cast or as-welded features deviate from what is acceptable, the S-Map will be the empty set. Consequently, in addition to reducing the time for setup in a fixture, S-Maps can serve as a valuable diagnostic to determine that a part should be either scrapped or reworked.
Hysteresis in Interoperability: Workflows Involving Multiple Representations of 3D Models
Authors: Jaiswal Prakhar , Rai Rahul , Nelaturi Saigopal
Published: December 2016

Various 3D solid model representation schemes are developed to capture and process geometrical information of physical 3D objects as accurately and precisely as possible with the consideration of storage and computational complexity. These representation schemes are error prone, and their limitations prohibit them to capture all the pertinent information perfectly for a complex 3D object. Many applications in design involve repetitive conversions between several representation schemes to efficiently evaluate and operate on solid models. Mapping one representation to other degrades the quality, correctness, and completeness of the information content. In this paper, we quantify the degradation of the proxy representation models by taking inspiration from the hysteresis concept applied in different fields, such as magnetism, mechanics, control systems, cell biology, and economics. We propose a method to compute the error remanence using quantitative measures of information content and quality of proxy models. We also discuss the areas of future research such as sequencing of operations in computational work-flows that would benefit by utilizing the error remanence metric.
Closed-Form Solutions for Electroacoustic Wave Energy Harvesting in a Coupled Plate-Harvester System
Authors: Darabi Amir , Leamy Michael
Published: December 2016

This paper introduces an analytical framework for predicting wave energy harvested by a circular piezoelectric layer from a harmonic point source excitation. The explored acoustic system analyzes a circular piezoelectric disk attached to an infinite host domain. An harmonic point source is located away from the piezoelectric disk on the infinite host layer. The analysis approach decomposes the system into two subdomains, the piezoelectric disk and an infinite plate, which are then separately analyzed. In contrast to traditional analysis methods for such systems (a sandwich of layers with different dimensions), this technique uses internal interaction forces between the different subdomains to find a close-form solution for the vibration of propagating waves over the entire field. In addition, the voltage generated by the harvester is calculated by using coupled electromechanical equations. The analysis is validated by comparing response quantities and frequency response functions at different points on the piezoelectric circular layer and host layers to those predicted using COMSOL simulations, which document good agreement. Analysis of this system is an important stepping stone to the next goal, which is optimization of energy captured from the propagating wave by designing boundary walls (reflector) on the host layer which focus the energy of the wave onto the piezoelectric domain. This focused energy can then be transferred to the electrical power by via a piezoelectric layer through an electrical circuit.
A Tight Upper Bound for Grid-Based Wind Farm Layout Optimization
Authors: Quan Ning , Kim Harrison
Published: December 2016

This paper uses the method developed by Billionnet et al. (1999) to obtain tight upper bounds on the optimal values of mixed integer linear programming (MILP) formulations in grid-based wind farm layout optimization. The MILP formulations in grid-based wind farm layout optimization can be seen as linearized versions of the 0-1 quadratic knapsack problem (QKP) in combinatorial optimization. The QKP is NP-hard, which means the MILP formulations remain difficult problems to solve, especially for large problems with grid sizes of more than 500 points. The upper bound method proposed by Billionnet et al. is particularly well-suited for grid-based wind farm layout optimization problems, and was able to provide tight optimality gaps for a range of numerical experiments with up to 1296 grid points. The results of the numerical experiments also suggest that the greedy algorithm is a promising solution method for large MILP formulations in grid-based layout optimization that cannot be solved using standard branch and bound solvers.
Redesigning a Reaction Control Thruster for Metal-Based Additive Manufacturing: A Case Study in Design for Additive Manufacturing
Authors: Woods Matthew R. , Meisel Nicholas A. , Simpson Timothy W. , Dickman Corey J.
Published: December 2016

Prior research has shown that powder bed fusion additive manufacturing (AM) can be used to make functional, end-use components from powdered metallic alloys, such as Inconel® 718 super alloy. However, these end-use products are often based on designs developed for more traditional subtractive manufacturing processes without taking advantage of the unique design freedoms afforded by AM. In this paper, we present a case study involving the redesign of NASA’s existing “Pencil” thruster used for spacecraft attitude control. The initial “Pencil” thruster was designed for, and manufactured using, traditional subtractive methods. The main focus in this paper is to (a) review the Design for Additive Manufacturing (DfAM) concepts and considerations used in redesigning the thruster and (b) compare it with a parallel development effort redesigning the original thruster to be manufactured more effectively using subtractive processes. The results from this study show how developing end-use AM components using DfAM guidelines can significantly reduce manufacturing time and costs while introducing new and novel design geometries.
Parameter Identification for a Longitudinal Dynamics Model Based on Road Tests of an Electric Vehicle
Authors: Batra Mohit , McPhee John , Azad Nasser L.
Published: December 2016

This paper presents a method to estimate the parameters of a longitudinal dynamic model using on-road testing of an electric vehicle. Data acquisition was undertaken on our test vehicle, a Toyota Rav4EV 2012, by collating signals from three different sources: Vehicle Measurement System (VMS) (consisting of wheel force, torque, wheel spin, wheel speed and position sensors), Global Positioning System (GPS) and the Controller Area Network (CAN) of the vehicle. A MATLAB/Simulink based non-linear least square parameter estimation algorithm was used to identify the vehicle parameters including the mass, location of center of gravity, frontal area, coefficient of drag, wheel inertia and road load parameters of the vehicle. A 14 degrees of freedom (DOF), longitudinal dynamics model of the Rav4EV was developed in the MapleSim software using the estimated parameters. The accuracy of the identified parameters and the model was validated by comparing the model output against the experimental data.
Automated Microassembly Sequence Planning With Sub-Assemblies
Authors: Seymour Joseph , Cappelleri David J.
Published: December 2016

Assembly sequence planning is an engineering problem that has been of great interest in the manufacturing field at the macro-scale. As more complex assemblies are desired at the micro and nano scales it is no longer feasible for human beings to plan and execute the production of these systems. A promising algorithm that allows optimization of assembly sequence plans that has been developed is called the Breakout Local Search. One drawback of this algorithm is its inability to consider the need for intermediate sub-assemblies to generate feasible solutions. Here an expansion to the BLS algorithm, called the Sub Assembly Generating BLS (SABLS) algorithm, is proposed. The fitness function of this new algorithm is also tailored to the specific constraints and motion primitives for a micromanipulation test-bed allowing for its use in microassembly applications. It is shown that the proposed algorithm is capable of generating optimized solutions that can be assembled with this limited degree of freedom system.
Thick Rigidly Foldable Origami Mechanisms Based on Synchronized Offset Rolling Contact Elements
Authors: Lang Robert J. , Nelson Todd , Magleby Spencer , Howell Larry
Published: December 2016

We present a general technique for achieving kinematic single-degree-of-freedom origami-based mechanisms with thick rigid panels using synchronized offset rolling contact elements. We present general design analysis for planar and 3D relative motions between panels and show physically realized examples. The technique overcomes many of the limitations of previous approaches for thick rigidly foldable mechanisms.
Exploring the Link Between Task Complexity and Students’ Affective States During Engineering Laboratory Activities
Authors: Hu Qianyu , Bezawada Shruthi , Gray Allison , Tucker Conrad , Brick Timothy
Published: December 2016

Assessment and feedback play an instrumental role in an individual’s learning process. Continued assistance is required to help students learn better and faster. This need is especially prominent in engineering laboratories where students must perform a wide range of tasks using different machines. One approach to understanding how students feel towards using certain machines is to assess their affective states while they use these machines. Affective state can be defined as the state of feeling an emotion. The authors of this work hypothesize that there is a correlation between students’ perceived affective states and task complexity. By adopting the Wood’s complexity model, the authors propose to assess how the correlations of perceived affective states of students change while they perform tasks of different complexity. In this study, each student performs a “hard” and an “easy” task on the same machine. Each student is given the same tasks using the same materials. Knowledge gained from testing this hypothesis will provide a fundamental understanding of the tasks that negatively impact students’ affective states and risk them potentially dropping out of STEM tracks, and the tasks that positively impact students’ affective states and encourage them to engage in more STEM-related activities. A case study involving 22 students using a power saw machine is conducted. Perceived affective states and completion time were collected. It was found that task complexity has an effect on subjects’ affective states. In addition, we observed some weak correlation between some of the perceived affective states and laboratory task performance. The distribution of correlation between affective states may change as the tasks change. With the knowledge of the relationship between task complexity and affective states, there is the potential to predict students’ affective states before starting a given engineering task.