bluuebunny/crossref_metadata_2025 huggingface dataset:
HIL Development of Control Algorithm for Vehicle Demand-Driven Production of H2 From an Al/Mg and H2O Reaction
Authors: Parker John , Poston Christopher , Roser Richard , Anstrom Joel , Cleary Timothy , Markovich Bryan
Published: September 2013

This technical paper provides instruction by example on how to apply hardware-in-the-loop (HIL) simulation for accelerated development of a complex control algorithm. The instruction provided in this technical paper is directed to HIL test bench setup, software, simulated and real hardware, and test methods. As an example, the authors reference their collaborative development project of the last couple of years, now completed. The objective of that project was to develop a demand-driven hydrogen production system and integrate it with a hydrogen-fueled internal combustion engine-powered vehicle test platform. The instruction provided in this technical paper is supported by data from the referenced project example.
Modeling Flutter-Based Microgenerators
Authors: Kafafy Raed , Javeed Abdulhakeem , Idres Moumen , Ihsan Sany
Published: September 2013

Flutter-based micro generators have been successfully demonstrated to power wireless sensors. Since environmental wind speeds vary widely, flutter-based micro generators which are designed to operate within particular range of wind speeds will underperform elsewhere. At low wind speeds, magnets embedded near the ends of the belt will not move the desired distance between the coils, thereby reducing the energy conversion. A broadband flutter-based micro generator will have pick-up coils embedded on several vibrating elements with different dimensions. The coils are particularly concentrated near the point of maximum speed to maximize power output. The variation in fluttering element dimensions allows the microgenerator to generate considerable power at a wide range of wind speeds. In this work, we develop a mathematical model for the flutter-based micro generator, which addresses the wind – structure interaction, induced vibrations and electromagnetic transduction. The model primarily makes use of equations from bridge deck and thin plane analysis of flutter due to their similarities, and they are formulated to provide the velocity. This is later fed into electromagnetic transduction equations to calculate the output power. The model is useful to determine the significant design parameters of a flutter-based micro generator. The dynamic response and power output of a broadband micro generator with coils embedded on a set of cantilever films vibrating with respect to an external permanent magnetic field are calculated.
Representations: Reconciling Design for Disassembly Rules With Design for Manufacturing Rules
Authors: Rayate Vikrant C. , Summers Joshua D.
Published: September 2013

The paper presents a tool for selecting appropriate Design for Manufacturing and Design for Assembly rules during product design while considering Design for Disassembly rules and end-of-life recovery conditions. This tool exposes the relations between the various types of design rules and end-of-life recovery parameters. Four different relationship types are developed in this research: recovery conditions and recovery options relationship, Design for Disassembly rules and recovery options relationship, Design for Disassembly rules and recovery conditions relationship, Design for Disassembly rules, and Design for Manufacturing and Design for Assembly rules relationship. The purpose of this research is to build these relations and transform these relationships into a database. The database serves as tool from which design rules can be retrieved by running queries. In addition to design rule retrieval, the tool also shows the relationships with various design rules, recovery options, and recovery conditions. This provides designers with information as to which rules are in conflict and which are complementary for the specific situation under consideration. To illustrate this tool, it is applied to motor-drive assembly and thermal gun sight, which are already design products. Additionally the application of the tool is demonstrated using a hypothetical scenario which involves products like coffee cup, cell phone and stapler.
Design Analytics: Capturing, Understanding, and Meeting Customer Needs Using Big Data
Authors: Van Horn David , Olewnik Andrew , Lewis Kemper
Published: September 2013

The evolution of design thinking has seen numerous challenges and advances in transforming information into knowledge for engineers to design systems, products, and processes. These transformations occur in three stages throughout a design process. In simple form, the early, middle, and late stages of a design process serve to develop an understanding of the customer’s needs, arrive at the final concept of the design, and analyze and support the performance and usage profile of the deployed product, respectively. The quality and accuracy of the input information and the effectiveness of each transformation determine the success or failure of the product. Capturing good information and converting it to knowledge are two important tasks that have motivated a long history of research in design processes and tools. In this paper, we propose Design Analytics (DA) as a new paradigm for significantly enhancing the core information-to-knowledge transformations. The overall aim is to capture, store, and leverage digital information about artifacts, their performance, and their usage. The information is transformed into knowledge in each of the three stages using various analytics and cyber-enabled tools such as design repositories and concept generators. The ultimate result is better performing and functioning products. As web analytics has transformed how companies interact with consumers on the internet, we expect DA to transform how companies design products with and for consumers. An illustrative case study is performed to demonstrate some of the foundations of DA in the redesign of a refrigerator.
An Analysis of Critical Factors in Medical Device Development to Design for FDA
Authors: Medina Lourdes A. , Okudan Kremer Gül E. , Wysk Richard A.
Published: September 2013

This paper provides a deeper understanding on the Food and Drug Administration’s (FDA) role in relation to medical devices. Specific considerations are given to the data FDA reports to the public domain as part of the 510(k) clearances and PMA approvals. Scientific treatment of such considerations has been a void in the literature prior to the work presented here. Critical factors are defined at the product level, where an empirical investigation is performed to study the impact of various factors in FDA’s decision time. The critical factors identified include regulatory components, product characteristics and the historical reference. Significant regulatory components include the submission types and the different types of classifications (product codes, risk classification and regulation number). Significant product characteristics included the factors specific to hip devices (cemented, constrained) and generalized factors applicable to most medical devices (intended use, context of use, function and material). The importance of historical reference, as an indication of various types of experience, showed the significance of company’s experience with FDA, and FDA’s experience in terms of product codes and product characteristics (body part, function, material and et cetera).
On the Design of Singularity-Free Cable-Driven Parallel Mechanism Based on Grassmann Geometry
Authors: Zou Yu , Zhang Yuru , Zhang Yaojun
Published: September 2013

This paper deals with the design of singularity-free cable-driven parallel mechanism. Due to the negative effect on the performance, singularities should be avoided in the design. The singular configurations of mechanisms can be numerically determined by calculating the rank of its Jacobian matrix. However, this method is inefficient and non-intuitive. In this paper, we investigate the singularities of planar and spatial cable-driven parallel mechanisms using Grassmann line geometry. Considering cables as line vectors in projective space, the singularity conditions are identified with clear geometric meaning which results in useful method for singularity analysis of the cable-driven parallel mechanisms. The method is applied to 3-DOF planar and 6-DOF spatial cable-driven mechanisms to determine their singular configurations. The results show that the singularities of both mechanisms can be eliminated by changing the dimensions of the mechanisms or adding extra cables.
Design and Fabrication of a Three-DOF MEMS Stage Based on Nested Structures
Authors: Kim Yong-Sik , Dagalakis Nicholas G. , Gupta Satyandra K.
Published: September 2013

This paper presents the design, fabrication and testing of a Micro Electro Mechanical Systems (MEMS) based positioning stage which is capable of generating translational motions along X, Y and Z axes, respectively. For this purpose, two existing 1 Degree of Freedom (DOF) in-plane positioning stages and one 1 DOF out-of-plane actuator are merged together for 3 DOF motions. For successful integration between three independent systems, a platform in the chosen 1 DOF in-plane stage is utilized to embed another system. For a successful combination between three independent systems, two nested structures are adapted as a serial kinematic mechanism. With the nested structures, one 1 DOF in-plane positioning stage is embedded into the other 1 DOF in-plane stage for in-plane translational motions along the X and the Y axes. And then, one 1 DOF out-of-plane actuator is embedded for the translational motion along the Z axis. The proposed 3 DOF system has demonstrated an ability to generate at least 20 μm along X, Y and Z axes, respectively. The cross talk between the three axes is also measured and is less than 4 percent of the intended displacement.
Dynamic Effects of Electrical Pitting in Steam-Turbine Tilting-Pad Thrust-Bearings
Authors: Pennacchi P. , Ricci R. , Chatterton S. , Borghesani P. , Vania A. , D’Antona G. , Pensieri C. , Rolla C.
Published: September 2013

This paper merges the analysis of a case history and the simplified theoretical model related to a rather singular phenomenon that may happen in rotating machinery. Starting from the first, a small industrial steam turbine experienced a very strange behavior during megawatt load. When the unit was approaching the maximum allowed power, the temperature of the babbitt metal of the pads of the thrust bearing showed constant increase with an unrecoverable drift. Bearing inspection showed that pad trailing edge had the typical aspect of electrical pitting. This kind of damage was not reparable and bearing pads had to replaced. This problem occurred several times in sequence and was solved only by adding further ground brushes to the shaft-line. Failure analysis indicated electrodischarge machining as the root fault.

A specific model, able to take into consideration the effect of electrical pitting and loading capacity decreasing as a consequence of the damage of the babbitt metal, is proposed in the paper and shows that the phenomenon causes the irretrievable failure of the thrust bearing.
Quantifying Customer Sacrifice for Use in Product Customization Problems
Authors: Porterfield Kalie , Ferguson Scott
Published: September 2013

Every time a customer selects a product from the shelf they make a purchase decision based on trade-offs between available offerings. The available products often exhibit feature excess at a price premium, feature deficiency at a price discount, or some combination of both. By purchasing one of these products a customer experiences some degree of sacrifice. This paper proposes the use of choice-based conjoint analysis and hierarchical Baysian modeling to calculate the perceived utility of a customer’s ideal product and the perceived utility of the best current alternative in the market. A customer’s sacrifice gap, a quantity that mass customization seeks to minimize, is defined as the difference between these values. This paper quantifies a market-average sacrifice gap and uses it in a theoretical product platform customization scenario. This scenario examines the effects of offering customization options on one attribute of a product at a time on a customer-centric objective (sacrifice gap) and a firm-centric objective (aggregate contribution). The results are also used to examine how customer sacrifice is minimized at an individual-level.
Developing Competencies for the 21st Century Engineer
Authors: Hawthorne Bryant , Sha Zhenghui , Panchal Jitesh H. , Mistree Farrokh
Published: September 2013

This is the second paper in a four-part series focused on a competency-based approach for personalized education in a group setting. In the first paper, we focus on identifying the competencies and meta-competencies required for the 21st century engineers. In this paper, we provide an overview of an approach to developing competencies needed for the fast changing world and allowing the students to be in charge of their own learning. The approach fosters “learning how to learn” in a collaborative environment. We believe that two of the core competencies required for success in the dynamically changing workplace are the abilities to identify and manage dilemmas. In the third paper, we discuss our approach for helping students learn how to identify dilemmas in the context of an energy policy design problem. The fourth paper is focused on approaches to developing the competency to manage dilemmas associated with the realization of complex, sustainable, socio-techno-eco systems.

The approach is presented in the context of a graduate-level course jointly offered at University of Oklahoma, Norman and Washington State University, Pullman during Fall 2011. The students were asked to identify the competencies needed to be successful at creating value in a culturally diverse, distributed engineering world at the beginning of the semester. The students developed these competencies by completing various assignments designed to collaboratively answer a Question for Semester (Q4S). The Q4S was focused on identifying and managing dilemmas associated with energy policy and the next generation bridging fuels. A unique aspect of this course is the collaborative structure in which students completed these assignments individually, in university groups and in collaborative university teams. The group and team structures were developed to ultimately aid individual learning. The details of the answer to the Q4S are elaborated in the other three papers which address identifying and managing dilemmas, specifically related to Feed-In-Tariff (FIT) policy and bridging fuels.

The fundamental principles of our approach include a shift in the role of the instructor to orchestrators of learning, shift in the role of students to active learners, providing opportunities to learn, shift in focus from lower levels to upper levels of learning, creation of learning communities, embedding flexibility in courses, leveraging diversity, making students aware of the learning process, and scaffolding. Building on our experience in the course, we discuss specific ways to foster the development of learning organizations within classroom settings. Additionally, we present techniques for scaffolding the learning activities in a distributed classroom based on systems thinking, personal mastery, mental models, a shared vision, and team learning. The approach enables personalized learning of individuals in a group setting.
Probabilistic Graphical Models as Tools for Evaluating the Impact of Usage-Context on the Environmental Performance of Products
Authors: Telenko Cassandra , Seepersad Carolyn
Published: September 2013

Environmentally conscious design is focused on reducing the environmental impact of engineered systems, but common practice in life cycle analysis overlooks the relationship between a product’s usage-context and its environmental performance. Existing studies rarely consider operational variability or the correlation between performance, design, and usage variables. Probabilistic graphical models (PGMs) provide the capability of not only evaluating uncertainty and variability of product use, but also correlating the results with the product’s features and usage context. This discussion explores the use of PGMs as a tool for evaluating operational variability in products and including the results in life cycle inventories. The tool is illustrated for environmentally conscious product design through an example study of an electric kettle.
Massively Parallel Granular Media Modeling of Robot-Terrain Interactions
Authors: Mukherjee Rudranarayan M. , Houlihan Ryan
Published: September 2013

This paper presents select results that demonstrate the feasibility of modeling the interactions of robotic systems with granular terrain through Discrete Element Modeling (DEM) using massively parallel computing systems. We report numerical simulation results of full 3D DEM simulations with the granular material modeled as a deformable bed of spherical granules. The mobility systems of the robots retain their CAD geometry and are represented as triangular meshes. The inter-granular interactions and the interactions between the CAD mesh triangles with the granules are modeled explicitly using a deformation-damping force field. The parameters of the force field are derived from physically measurable properties. We model friction, cohesion, and shearing and other interactions among the granules, and between the CAD mesh and the granules. The simulations involve granular beds with number of granules in the order of several hundred thousand to several millions. Temporally, we report simulations in the order of several seconds. These simulations were run on parallel clusters with number of processors ranging from 100 to 256. We present the findings from a number of simulations ranging including wheeled and legged mobility systems, and robotic tools in micro-gravity environments.
Trajectory Planning of Cable-Suspended Parallel Robots Using Interval Positive-Definite Polynomials
Authors: Ren Ping , Gosselin Clément
Published: September 2013

In this paper, the dynamic point-to-point trajectory planning of cable-suspended robots is investigated. A simple planar two-degree-of-freedom (2-dof) robot is used to demonstrate the technique. In order to maintain the cables’ positive tension, a set of algebraic inequalities is derived from the dynamic model of the 2-dof robot. The trajectories are defined using parametric polynomials with the coefficients determined by the prescribed initial and final states, and the variable time duration. With the polynomials substituted into the inequality constraints, the planning problem is then converted into an algebraic investigation on how the coefficients of the polynomials will affect the number of real roots over a given interval. An analytical approach based on a polynomial’s Discrimination Matrix and Discriminant Sequence is proposed to solve the problem. It is shown that, by adjusting the time duration within appropriate ranges, it is possible to find positive-definite polynomials such that the polynomial-based trajectories always satisfy the inequality constraints of the dynamic system. Feasible dynamic trajectories that are able to travel both beyond and within the static workspace will exploit more potential of the cable-suspended robotic platform.
Dynamics Enhancements of Advanced LIGO Multi-Stage Active Vibration Isolators and Related Control Performance Improvement
Authors: Matichard Fabrice , Mason Ken , Mittleman Richard , Lantz Brian , Abbott Ben , MacInnis Myron , LeRoux Adrien , Hillard Michael , Ramet Celine , Barnum Sam , Stein Andy , Foley Stephany , Radkins Hugh , Kissel Jeff , Biscans Sebastien , Lhuillier Vincent
Published: September 2013

The control bandwidth and performance of active vibration isolation systems are usually directly related to the system dynamic characteristics. In this paper, we present results from a 4 years study carried out to improve the dynamical response and control performance on the two-stage isolator designed for Advanced LIGO detectors. The paper will focus on the platform’s first stage to illustrate prototyping, optimization, final design and the experimental results obtained during this program. The system concept, architecture and prototype will be presented. The factors initially limiting the prototype’s performance will be analyzed. Solutions based on sensors relocation, payload reduction, structural stiffening and passive techniques to damp the residual high frequency flexible modes will be presented. Experimental results obtained with the prototype will be compared with the system’s final version. The series of improvement obtained help not only to increase the system’s bandwidth, robustness and performance but also to simplify and speed up the control commissioning, which is very important for the Advanced LIGO project that will be using 5 of these platforms in each of its 3 detectors.
Confirmation and Cognitive Bias in Design Cognition
Authors: Hallihan Gregory M. , Cheong Hyunmin , Shu L. H.
Published: September 2013

The desire to better understand design cognition has led to the application of literature from psychology to design research, e.g., in learning, analogical reasoning, and problem solving. Psychological research on cognitive heuristics and biases offers another relevant body of knowledge for application. Cognitive biases are inherent biases in human information processing, which can lead to suboptimal reasoning. Cognitive heuristics are unconscious rules utilized to enhance the efficiency of information processing and are possible antecedents of cognitive biases. This paper presents two studies that examined the role of confirmation bias, which is a tendency to seek and interpret evidence in order to confirm existing beliefs. The results of the first study, a protocol analysis involving novice designers engaged in a biomimetic design task, indicate that confirmation bias is present during concept generation and offer additional insights into the influence of confirmation bias in design. The results of the second study, a controlled experiment requiring participants to complete a concept evaluation task, suggest that decision matrices are effective tools to reduce confirmation bias during concept evaluation.
GPU-Based Parallel Simulation of Silicon Anisotropic Etching
Authors: Li Jianhua , Wang Yan , Chen Jingyuan , Yan Li
Published: September 2013

Silicon anisotropic etching simulation, based on geometric model or cellular automata (CA) model, is highly time-consuming. In this paper, we propose two parallelization methods for the simulation of the silicon anisotropic etching process with CA models on graphics processing units (GPUs). One is the direct parallelization of the serial CA algorithm, and the other is to use a spatial parallelization strategy where each crystal unit cell is allocated to a thread in GPU. The proposed simulation methods are implemented with the Compute Unified Device Architecture (CUDA) application programming interface. Several computational experiments are taken to analyze the efficiency of the methods.
Low Voltage Electrostatic Actuation and Displacement Measurement Through Resonant Drive Circuit
Authors: Park Sangtak , Abdel-Rahman Eihab
Published: September 2013

Most electrostatic actuators fabricated by MEMS technology require high actuation voltage and suffer from the pull-in phenomenon that limits the operation range. We present an amplitude-modulated resonant drive circuit to drive electrostatic actuators at much lower supply voltage than that of conventional actuators to extend their operation range. Analytical and numerical models facilitate stability analysis of electrostatic actuators coupled with the resonant drive circuit. We study the impact of parasitic capacitance and the quality factor of the resonant drive circuit on the operation range of electrostatic actuators. Furthermore, we present a new method to measure the displacement of electrostatic actuators by sensing the phase delay of the actuation voltage with respect to the input voltage. This measurement method allows us to easily incorporate feedback control into existing electrostatic actuators without any modification to the actuator itself.
Brain Activation Analysis of Voluntary Movement and Passive Movement Using Near-Infrared Spectroscopy
Authors: Watanuki Keiichi , Hirayama Kenta , Kaede Kazunori
Published: September 2013

During neural activity in the brain, humans transmit and process information and decide upon actions or responses. When neural activity occurs, blood flow and blood quantity increase in the tissue near the active neurons, and the ratio of oxygenated to deoxygenated hemoglobin in the blood changes. In this paper, we used near-infrared spectroscopy (NIRS) to determine the state of hemoglobin oxygenation at the cerebral surface and on that basis performed real-time color mapping of brain activity (the brain activation response) in the target regions. In this paper, we describe measurements of brain activation using NIRS so as to clarify any differences between conscious and unconscious movement. Bio-locomotion is divided into voluntary movements, which are made voluntarily and consciously, and passive movements, which are made passively and unconsciously. Accordingly, in this paper we investigate the brain activation associated with these two types of movements. The subject successively moves his/her lower legs through knee bends. We measure the brain activities while the subject, who is sitting on a chair moves back and forth. In addition, we carry out an experiment on the effects of the existence or nonexistence of movement caused by vibration on brain activities to consider the results.
Analysis and Optimization of Automotive Structure’s Bending Stiffness Using Beam Elements
Authors: Tebby Steven , Barari Ahmad , Esmailzadeh Ebrahim
Published: September 2013

Optimum design of vehicle’s structure is an important task in its development. The structure of a vehicle plays complex interactions with the other vehicle components and has significant impact on the performance of the vehicle. Structural design is usually completed by a complex iterative process. The design changes at late design stages effect many other parameters in the design of vehicle. Therefore, it is highly valuable for designers to employ simple but effective analyses at the early design stages. One method of analysis is using Simple Structural Surfaces. This method utilizes planar sheets to model the vehicle structure and allows the determination of the forces in each sheet. The major drawback of this method is its inability to easily determine deflections in a structure. To overcome this drawback a method that uses beam elements to represent the vehicle structure has been developed. This method uses a numerical finite element method and is able to determine unknown deflections and reaction forces as well as the internal loading on each member. This method can also be readily adapted to allow for parametric optimization for bending stiffness. The parameters associated with each beam element are the length, orientation and the beam characteristics of beams’ cross-sectional area and moment of inertia. An automated process is developed that manipulates some of these parameters to develop a structure that will have the greatest bending stiffness.
Model Development Under Uncertainty via Conjoint Analysis
Authors: Stone Thomas M. , Choi Seung-Kyum , Amarchinta Hemanth
Published: September 2013

Model development decisions are critical in the early phases of engineering design. Engineering models serve as representations of reality that help designers understand input/output relationships, answer ‘what-if’ questions, and find optimal design solutions. Upon making model development decisions, the designer commits a large percentage of the costs associated with reaching design goals/objectives. The decisions dictate cost-drivers such as experimental setups and computation time. Unfortunately, the desire to develop the most accurate model competes with the desire to reduce costs. The designer is ultimately required to make trade-offs between attributes when choosing the best model development decision. Hence it is critical to develop tools for selecting the model development decision that appropriately balances trade-offs. A framework is proposed for model development decision-making. Conjoint Analysis (CA) is implemented in order to handle trade-offs among attributes. Thus, the framework can be used to make optimal decisions based on the assessment of multiple attributes. Moreover, the framework addresses the uncertainty that exists early in model design. Imprecision in model parameters are estimated and propagated through the model. In particular, the proposed decision framework is employed to select the optimal model development decision with respect to the final phase of experimentation. Preference intervals are evaluated in order to choose which final experimentation to perform. The decision framework proves to be useful for making model development decisions under uncertainty by considering the preference of multiple attributes and the imprecision of said attributes that is prevalent in early model development phases.
Decentralized Multi-Robot Teams Using Wheeled Manipulation for Object Transportation
Authors: Ringold Tyson L. , Cipra Raymond J.
Published: September 2013

Object transportation is an especially suitable task for cooperative mobile robots where the carrying capacity of an individual robot is naturally limited. In this work, a unique wheeled robot is presented that, when used in homogeneous teams, is able to lift and carry objects which may be significantly larger than the robot itself. A key feature of the presented robot is that it is devoid of articulated manipulation mechanisms, but instead relies on its drive wheels for object interaction. After a brief introduction to the mechanics of this mobile robot, a behavior-based lifting and carrying strategy is developed that allows the robot to cooperatively raise an object from the ground, transition into a carrying role, and then transport the object across cluttered, unstructured terrain. The strategy is inherently decentralized, allowing an arbitrary number of robots to participate in the transportation task. Dynamic simulation results are then presented, showing the effectiveness of the strategy.
Perception and Interpretation: Points of Focus in Design Sketches
Authors: Sagan Emma , Yang Maria
Published: September 2013

During the design of a product, designers may show a potential customer or other stakeholder a drawing of a design concept in order to elicit feedback that can be used to inform further development of the design. Designers may desire feedback on specific aspects of a concept, such as its shape or size, but viewers may in fact focus on other elements of the drawing itself, such as color or surface texture. Viewers translate their visual perception of these representations into perceived understanding, but how can we know whether their interpretations are consistent with the designer’s intention? This paper evaluates the translation of four different product sketches by 163 participants. This study also considers how aesthetic preference and concrete information might influence a viewer’s opinion of an object. Results suggest that viewers were likely to recall physical aspects from a sketch of a product (material, shape) as well as its function. Findings also suggest that individuals preferred images that were overall more informative rather than aesthetically pleasing. Additionally, our research suggests that individuals were more likely to recall the texture, material or perceived efficiency of an object than recall the name of the object, its function, or its shape.
Assessing the Use of Function Models and Interaction Models Through Concept Sketching
Authors: Caldwell Benjamin W. , Ramachandran Raveesh , Mocko Gregory M.
Published: September 2013

Functional representations are often used in the conceptual stages of design because they encourage the designer to focus on the intended use and purpose of a system rather than the physical solution. Function models have been proposed by many researchers as a tool to expand the solution search space and guide concept generation, and many design tools have been created to support function-based design. These tools require designers to create function models of new or existing artifacts, but there is limited published research describing the level of functional detail that should be included in a model or the appropriate level of abstraction to model artifacts. Further, there is limited experimental evidence that designers use function models when generating concepts, and controlled experiments in the literature have focused on ideation rather than function models. Therefore, this research focuses on how artifacts should be modeled to guide concept generation in conceptual design.

In this research, three artifact representations are studied: function models, interaction models, and pruned function models. A user study was conducted in which participants were asked to design a new device based on a problem statement, a set of requirements, and a treatment. Participants were randomly assigned a treatment of a function model, interaction model, pruned model, or no model. A conformance metric was developed to measure the extent to which participants used a model when generating concept sketches. The results show that the functional conformance of participants using a pruned model is approximately 40% higher than that of participants using a function model. These results demonstrate that the use of a specific level of functional detail improves the use of functions within the model for concept generation.
Energy Efficiency and Stability of a Nonlinear Coupled-Oscillator Model of Hopping With Elastically-Suspended Loads
Authors: Ackerman Jeffrey , Seipel Justin
Published: September 2013

Elastically suspending a load with a compliant suspension system can increase the energy efficiency of legged locomotion and load carrying in humans, animals, and robots. In prior work, we developed a simple linear model from first principles and showed that elastically-suspended loads reduce the energy cost and stability of locomotion. In this paper, we expand on this model by adding flight phases, transforming it into a nonlinear hybrid system that is a more realistic representation of human hopping and high-speed locomotion more generally. The addition of flight phases causes a counterintuitive shift in the behavior of the double-mass coupled-oscillator system. With the addition of flight phases, the tuning of the elastic load suspension becomes more critical in order to reduce the energy cost of human hopping. Elastically-suspended loads also increased the overall system stability compared to rigidly-attached loads when the system exhibits flight phases. Therefore, under certain conditions, a human hopping with an elastically-suspended load can exhibit increased energy efficiency and stability compared to a rigidly-attached load. This study will help improve our understanding of elastically-suspended loads and could enable the design of tuned suspension systems for load carrying.
Towards Robustly Stable Musculo-Skeletal Simulation of Human Gait: Merging Lumped and Component-Based Modeling Approaches
Authors: Seipel Justin
Published: September 2013

The objective of work presented in this paper is to increase the center-of-mass stability of human walking and running in musculo-skeletal simulation. The approach taken is to approximate the whole-body dynamics of the low-dimensional Spring-Loaded Inverted Pendulum (SLIP) model of locomotion in the OpenSim environment using existing OpenSim tools. To more directly relate low-dimensional dynamic models to human simulation, an existing OpenSim human model is first modified to more closely represent bilateral above-knee amputee locomotion with passive prostheses. To increase stability further beyond the energy-conserving SLIP model, an OpenSim model based upon the Clock-Torqued Spring-Loaded-Inverted-Pendulum (CT-SLIP) model of locomotion is also created. The result of this work is that a multi-body musculo-skeletal simulation in Open-Sim can approximate the whole-body sagittal-plane dynamics of the passive SLIP model. By adding a plugin controller to the OpenSim environment, the Clock-Torqued-SLIP dynamics can be approximated in OpenSim. To change between walking and running, only one parameter representing the preferred period of a stride is changed. The result is a robustly stable simulation of the center-of-mass locomotion for both walking and running that could serve as a first step toward increasingly anatomically accurate and robustly stable musculo-skeletal simulations.
Optimization Guidelines in Decision Based Design
Authors: Pandey Vijitashwa , Majcher Monica , Mourelatos Zissimos P.
Published: September 2013

In order to maximize the potential of decision based design, optimization should be an integral part of the process. In this paper, several guidelines are proposed while assessing and fitting utility functions, defining constraint sets, defining backtracking rules and choosing optimization algorithms. We discuss the central role convexity plays in optimization and how it is relevant to maximizing utility functions of risk-averse decision makers, which are the most common type of decision makers. Strong convexity and Lipschitz continuity are also relevant to the discussion since they allow finding optimal designs and facilitate proofs of convergence. The commonly used exponential form is shown to have these properties. We further discuss the motivation to backtrack within an optimization process in order to account for varying preferences of the decision maker across the design space. Design implications of these guidelines are also covered. We conclude with a summary of guidelines and observations. A discussion on future work regarding optimization under uncertain designer preferences is also presented.
Mask Image Planning for Deformation Control in Projection-Based Stereolithography Process
Authors: Xu Kai , Chen Yong
Published: September 2013

In this research, we investigate the shrinkage related deformation control for a mask-image-projection-based Stereolithography process (MIP-SL). Based on a Digital Micromirror Device (DMD), MIP-SL uses an area-processing approach by dynamically projecting mask images onto a resin surface to selectively cure liquid resin into layers of an object. Consequently, the related additive manufacturing process can be much faster with a lower cost than the laser-based Stereolithography Apparatus (SLA) process. However, current commercially available MIP-SL systems are based on Acrylate resins, which have bigger shrinkages than epoxy resins that are widely used in the SLA process. Consequently controlling size accuracy and shape deformation in the MIP-SL process is challenging. To address the problem, we evaluate different image exposing strategies for projection mask images. A mask image planning method and related algorithms have been developed for the MIP-SL process. The planned mask images have been tested by using a commercial MIP-SL machine. The experimental results illustrate that our method can effectively reduce the deformation by as much as 32%. A discussion on the test results and future research directions are also presented.
Second Order Perturbation Analysis of a Forced Nonlinear Mathieu Equation
Authors: Ramakrishnan Venkatanarayanan , Feeny Brian F.
Published: September 2013

The present study deals with the response of a forced nonlinear Mathieu equation. The equation considered has parametric excitation at the same frequency as direct forcing and also has cubic nonlinearity and damping. A second-order perturbation analysis using the method of multiple scales unfolds numerous resonance cases and system behavior that were not uncovered using first-order expansions. All resonance cases are analyzed. We numerically plot the frequency response of the system. The existence of a superharmonic resonance at one third the natural frequency was uncovered analytically for linear system. (This had been seen previously in numerical simulations but was not captured in the first-order expansion.) The effect of different parameters on the response of the system previously investigated are revisited.
Vibration Analysis and Optimization of Sandwiched Beam Structure Using Higher Order Variation of Core Layer Displacement
Authors: Grewal Jasrobin Singh , Sedaghati Ramin , Esmailzadeh Ebrahim
Published: September 2013

Vibration characteristic of a sandwiched beam type structure is analyzed using the finite element method based on a higher order model for displacement field in the core layer of the structure. Results of the higher order and linear models were compared with those of experimental ones reported in literature and shown that higher order model provides more accurate results than the linear model. The parametric studies for the developed model are presented to indicate the effect of the core thickness on the loss factor and the natural frequencies, and the results are compared with those obtained for the linear model. Finally, using the higher order model, an optimization problem is formulated to find the optimal distribution and the number of partial treatments in order to achieve highest damping value in the sandwiched beam with various boundary conditions.
An investigation of the effects of interference speech on short-term memory for verbally presented prose
Authors: Lodico Dana M. , Torres Rendell R. , Shimizu Yasushi , Hunter Claudia
Published: September 2013

This study investigates the effects of interference speech and the built acoustical environment on human performance, and the possibility of designing spaces to architecturally meet the acoustical goals of office and classroom environments. The effects of room size, geometry, and acoustical parameters on human performance are studied through human subject testing. Three experiments are used to investigate the effects of distracting background speech on short-term memory for verbally presented prose under constrained laboratory conditions. Short-term memory performance is rated within four different acoustical spaces and five background noise levels, as well as a quiet condition. The presentation will cover research methods, results, and possibilities for furthering this research. [Work supported by the Program in Architectural Acoustics, School of Architecture, Rensselaer Polytechnic Institute.]
Classroom acoustics in public schools: A case study
Authors: Loro Carmen P. , Zannin Paulo T.
Published: September 2013

The acoustic quality of a standard classroom (Standard 23) of the public school system in the city of Curitiba has been evaluated. This standard has a central circulation aisle with two classrooms in each side. Each room has windows to the outside and to the internal aisle. Additionally, the aisle has a 6-m-high zenithal skylight, together composing the building’s main lighting and ventilation system. But, Standard 23 lacks acoustic quality of the classrooms. In order to assay this, measurements have been performed under several conditions, using the Building Acoustics System of Bruel & Kjaer. The measured reverberation time (RT) of the four classrooms for a frequency of 500 Hz was: 1.65 s (empty classroom), 1.15 s (20 students in the room), and 0.76 s (40 students). According to WHO recommendations, the ideal RT in classrooms should be around 0.6 s. DIN 18041 establishes an RT between 0.8 and 1.0 s, to allow for adequate intelligibility. Background noise in an empty room was 63.3 dB (A), above the limit established by the Brazilian standard of acoustic comfort: 40 dB (A). The reaction of students and teachers has indicated that the main source of acoustic discomfort is the noise generated by the neighboring classrooms.
Bat echolocation calls: Orientation to communication
Authors: Fenton M. Brock
Published: September 2013

Bats hunting flying insects adjust the design of their echolocation calls according to the situation in which they forage and stage in an attack. Changes in call design across attack sequences alert other bats within earshot to the presence of prey, demonstrating a continuum in roles for biosonar signals between orientation and communication. Many aerial-feeding bats change the design of their echolocation calls in the presence of echolocating conspecifics. Bats may change frequency parameters, durations, and/or intensities of their calls. While a variety of free-tailed bats (Molossidae Otomops martiensseni, Tadarida teniotis, Molossus molossus) consistently change their echolocation calls when more than one bat is flying in an area, at least one sheath-tailed bat (Emballonuridae Taphozous perforatus) does not. Changes in echolocation calls may maximize jamming avoidance and/or enhance the communicative function of the calls. The data for molossids support the hypothesis that when hunting some species fly in formation. Here, variation in individual call design could provide positional information and reduce the chances of mid-air collisions.
Impact of the chorus environment on temporal processing of advertisement calls by gray treefrogs
Authors: Schwartz Joshua , Huth Kenneth , Lasker Jeffrey
Published: September 2013

Male gray treefrogs advertise for mates using calls that consist of a series of pulses. Pulse duration, interpulse interval, and pulse shape determine whether a call is recognized as a conspecific signal by females. Females use call rate and call pulse number to assess relative calling performance by males, and prefer males that display high calling efforts. However, within choruses call overlap among males and background noise can compromise the ability of females to detect and correctly interpret temporal information in calls. Phonotaxis tests using calls suffering from different patterns of overlap or with internal gaps were used to investigate specific consequences of interference and masking as well as mechanisms that might alleviate such problems. Our data indicate that females do not employ a process analogous to phonemic restoration to ‘‘fill in’’ missing call segments; however, if a sufficient percent of call elements fall within species-specific ranges, females may ignore call anomalies. Additional findings are generally consistent with those from a recent study on anuran auditory midbrain neurons that count and indicate that inappropriate pulse intervals can reset the pulse counting process. [Work supported by NSF and a Pace University Eugene M. Lang Research Fellowship.]
Clinical applications of very high frequency ultrasound in ophthalmology
Authors: Silverman Ronald H. , Coleman D. Jackson , Reinstein Dan Z. , Lizzi Frederic L.
Published: September 2013

The eye is ideally suited for diagnostic imaging with very high frequency (>35 MHz) ultrasound (VHFU) because of its peripheral location and cystic structure. VHFU allows high resolution visualization of pathologies affecting the anterior segment of the eye, including tumors, cysts, foreign bodies, and corneal pathologies. We developed a series of prototype instruments suitable for ophthalmic studies using both polymer and lithium niobate transducers, with digitization of radiofrequency echo data at up to 500 MHz. While initially using linear scan geometries, we subsequently developed an arc-shaped scan matched to the curvature of the 0.5-mm-thick cornea to circumvent the effect of specular deflection of the ultrasound beam produced by the corneas curved surface. This technique allowed us to obtain data across the entire cornea and determination of the thickness of each corneal layer, including the epithelium (approximately 50 microns in thickness) and the surgically induced interface produced in LASIK, the most common form of refractive surgery. By scanning in a series of meridians, and applying optimized signal processing strategies (deconvolution, analytic signal envelope determination), corneal pachymetric maps representing the local thickness of each layer can be generated and aid in diagnosis of surgically induced defects or refractive abnormalities.