bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnitude of Axle Tramp Response to Partially Detreaded Tire Imbalance in Highway-Speed Driving
Authors: Semones Paul T. , Renfroe David A.
Published: September 2013

Tire tread separations on light trucks and SUVs have resulted in numerous catastrophic highway accidents over the past two decades in the United States. These accidents frequently involve single-vehicle rollovers or deviations of the impaired vehicle into oncoming traffic, where high speed frontal collisions may ensue.

On light trucks and SUVs equipped with a Hotchkiss rear suspension, one explanation for the loss of driver control during an in-process rear tire tread separation is solid axle tramp response to the imbalanced separating tire. This explanation has met with some controversy. The present study will demonstrate that the imbalance forces generated at highway speeds from a partially detreaded tire are sufficient to induce continuous cyclical axle tramp, and can even be sufficient to completely elevate rear-axle tires out of contact with the paved roadway. This imbalance-induced tramping action may be exacerbated during braking and the vehicle’s terminal yaw, when rear traction is crucial to avoiding a catastrophic accident. In addition to test data, several field examples of such events are presented.

A key metric of solid axle response to an imbalanced, partially detreaded tire is shock absorber motion. In the present study, shock absorber displacement on the test vehicles, as measured during highway speed tread separation axle tramp events, is found to oscillate through a stroke generally less than one inch (2.5 cm) in length at a frequency in excess of 10 Hz. Peak instantaneous velocities of the shock absorber have been observed as high as 40 in/s (16 cm/s) or more during straight driving under axle tramp conditions.

Confirming several previously published findings, the present study shows that increasing shock damping force at the higher operational velocities of the shock absorber reduces the magnitude of axle tramp and assists in keeping the rear axle tires in contact with the ground. Additionally, increasing the distance between the shock absorbers by moving them closer to the wheels provides the same advantage.
Unsteady Aerodynamic Modeling and Flutter Analysis of Long-Span Suspension Bridges
Authors: Arena Andrea , Lacarbonara Walter , Marzocca Pier
Published: September 2013

A parametric one-dimensional model of suspension bridges is employed to investigate their static and dynamic aeroelastic behavior in response to a gust load and at the onset of flutter. The equilibrium equations are obtained via a direct total Lagrangian formulation where the kinematics for the deck, assumed to be linear, feature the vertical and the chord-wise displacements of the deck mean axis and the torsional rotations of the deck cross sections, while preserving their shape during rotation. The cables elasto-geometric stiffness contribution is obtained by condensing the equilibrium in the longitudinal direction assuming small horizontal displacements and neglecting the cable kinematics along the bridge chord-wise direction. The equations of motion are linearized about the prestressed static aeroelastic configuration and are obtained via an updated Lagrangian formulation.

The equations of motion governing the structural dynamics of the bridge are coupled with the incompressible unsteady aero-dynamic model obtained by a set of reduced-order indicial functions developed for the cross section of a suspension bridge, here represented by a rectangular cross-section. The space dependence of the governing equations is treated using the Galerkin approach borrowing as set of trial functions, the eigenbasis of the modal space. The time integration is subsequently performed by using a numerical scheme that includes the modal reduced dynamic aeroelastic Ordinary Differential Equations (ODEs) and the added aerodynamic states also represented in ODE form, the latter being associated with the lag-state formulation pertinent to the unsteady wind-induced loads.

The model is suitable to analyze the effect of a time and space non uniform gust load distributed on the bridge span. The obtained aeroelastic system is also suitable to study the onset of flutter and to investigate the sensitivity of the flutter condition on geometrical and aerodynamic parameters. The flutter instability is evaluated using appropriate frequency and time domain characteristics. The parametric continuum model is exploited to perform dynamic aeroelastic flutter analysis and gust response of the Runyang Suspension Bridge over the Yangtze river in China.
A Flexible Control System for Automated Atomic Force Microscope Based Micro-/Nanomanipulation
Authors: Krohs Florian , Fatikow Sergej
Published: September 2013

Within the last years, atomic force microscopy (AFM), which was primarily invented for image acquisition, has become subject of increasing interest for nanomanipulation and nanofabrication issues. The AFM offers several advantages when compared to other technologies that enable for high precision manipulation. Its ability to operate under different ambient conditions (gas, vacuum, liquids) and also the very low requirements concerning sample properties (no need for conducting or vacuum-compatible material) makes the device a suitable and flexible tool for manipulating at the nanoscale, either for structuring surfaces with nanometric precision or for handling individual nanoobjects. Applications of AFM-based manipulations are manifold which are the prototyping of novel nanoscale devices, reparation or modification of nanostructures, or the characterization and handling of biological samples. However, even though the AFM basically offers all these kinds of manipulation techniques, commercial systems are designed mainly for image acquisition and thus often do not provide suitable control mechanisms to perform micro-/nanomanipulations with the flexibility that is needed. E.g. customizable feedback loops, arbitrary tip movements, varying forces and automation facilities are features that are required for complex nanoscale device fabrication. In this paper, a novel AFM control system and its application for micro-/nanomanipulation and -manufacturing will be presented. The paper is organized as follows. First, an overview on the design of the controller software and hardware is given followed by a description of a method for the compensation of thermal drift. Experimental results are presented, both for the handling of individual carbon nanotubes and for the automated structuring of a gold layer by AFM-based mechanical scratching. Last, the paper is concluded with a prospect to future experiments that will become possible by the new AFM control system.
Low-G Electrostatically Actuated Resonant Switch
Authors: Ramini Abdallah , Younis Mohammad I. , Su Quang T.
Published: September 2013

This work investigates a new concept of an electrostatically actuated resonant switch (EARS) for earthquake detection and low-g seismic applications. The resonator is proposed to operate close to instability bands of frequency-response curves, where it is forced to pull-in if operated within these bands. By careful tuning, the resonator can be made to enter the instability zone upon the detection of the earthquake signal, thereby pulling-in as a switch. Such a switching action can be functionalized for alarming purposes or can be used to activate a network of sensors for seismic activity recording. The EARS is modeled and its dynamic response is simulated using a nonlinear single degree of freedom model. Experimental investigation is conducted demonstrating the EARS capability of being triggered at small levels of acceleration as low as 0.02 g. Experimental data and simulation results are compared showing good agreement.
Network Target Coordination for Optimal Design of Decomposed Systems With Consensus Optimization
Authors: Wang Wenshan , Guarneri Paolo , Fadel Georges , Blouin Vincent
Published: September 2013

The complexity of managing multidisciplinary engineering systems offers an unprecedented opportunity to investigate decomposition methods, which separate a system into a number of smaller subsystems that can be designed in multiple physical locations and coordinate the design of the subsystems to collaboratively achieve the original system design. This paper studies a network target coordination model for optimizing subsystems that are distributed as multiple agents in a network. To solve these coupled subsystems concurrently, we consider the “consensus optimization” approach by incorporating subgradient algorithms so that the master problem or auxiliary design variables required by most distributed coordination methods are not needed. The method allows each agent to conduct its optimization by locally solving for coupling variables with the information obtained from other agents in the network in an iteratively improving process. The convergence results of a geometric programming problem that satisfies the convexity assumption is provided. Moreover, two non-convex examples are tested to investigate the convergence characteristics of the proposed methods.
Coupled Pitch Links for Multi-Harmonic Isolation Using Fluidic Circuits
Authors: Scarborough Lloyd H. , Rahn Christopher D. , Smith Edward C. , Koudela Kevin L.
Published: September 2013

Replacing rigid pitch links on rotorcraft with coupled fluidic devices has the potential to reduce the aerodynamic blade loads transmitted through the pitch links. Analytical models of two fluidic devices coupled with three different fluidic circuits are derived. These passive fluidlastic systems are tuned, by varying the fluid inertances and capacitances of each fluidic circuit, to reduce the transmitted pitch-link loads for up to three main-rotor harmonics. The simulation results show loads reduction at the targeted odd and even harmonics of at least 95% and 72%, respectively.
Modeling and Simulation of Mecano-Welding Process for Cylinders
Authors: Feng Zhengkun , Champliaud Henri
Published: September 2013

Pyramidal three-roll bending is widely used in manufacture due to its simple configuration and advantage for thick plate roll bending. However, there remain two planar zones near the front and rear ends of the bent shape. A mecano-welding process which provides improved circularity of the bent shape is proposed in this paper. This process includes three sub-processes: the first sub-process is the roll bending from a plate with cylindrical rolls; the second sub-process is the gas metal arc-welding process used to join the gap of the bent tubular section; the third sub-process is the rerun roll bending of the welded shape. Results of the numerical simulation of the first two sub-processes under the well-known ANSYS and ANSYS/LS-DYNA environment are reported. The bent shape after the first roll bending, the distributions of the temperature and residual stress after the welding are illustrated and discussed.
Postponing Representation Errors Through a Mix of Symbolic and Numerical Computation in Data Fitting
Authors: Venkataraman P.
Published: September 2013

Simple data fitting schemes involve tradeoff between the number of terms in the representation and the accuracy of the fit due to finite number of digits used to represent real numbers. This is also true for functional representation of data, where a known family of functions must be chosen to represent the data. Often these functions must also establish higher order continuity in the data. In practice, polynomial representation of data is very popular, either directly or indirectly through parameterized description such as NURBS. In this case the function approximation requires determining the constants that multiply the polynomial terms. Bezier functions, a special B-spline, can represent the data and the derivatives with fidelity. These functions are established by minimizing the squared error between the data and the representation. The Bezier representation can be determined numerically through simple matrix operations. The accuracy increases with the order of the polynomials until round-off errors becomes a factor. A completely numerical approach will compute faster but will limit the order of the polynomial due to round-off error. Symbolic processing on the other hand extends precision with more terms in representation, but is difficult to determine explicitly. Current symbolic software systems allow translation of the symbolic representation into efficient numerical representation for the application of optimization. This combination improves accuracy of the representation by postponing round off errors. This is demonstrated by application to two examples, one two-dimensional and the second, three-dimensional.
Simulation-Based Design of Wind-Turbine Sealing Solutions Using a Systematic Approach to Robust Concept Exploration
Authors: Schönberg Frank , Messer Matthias
Published: September 2013

Designing sealing solutions in wind turbines made of elastomeric materials that are robust to various uncertainties from manufacturing errors, material imperfections and wind turbine operation is a challenging task. In this paper, we focus on the simulation-based design of material properties and geometrical dimensions of such sealing solutions. We use a systematic approach to robust concept exploration based on a multi-objective decision formulation, the compromise Decision Support Problem (cDSP). Besides using the rather traditional Archimedean or standard utility function based goal formulations in the cDSP, we leverage the conjoint analysis approach to facilitate the preference elicitation process for the various stakeholders involved in the complex product development processes in industrial practice. By parametrically tailoring geometrical dimensions and material properties, characteristics that are superior to those of more heuristic sealing designs and less sensitive to imperfections in the processing and manufacturing routes as well as operation of the wind turbine are achieved. We compare base-line and various robust solutions from traditional Archimedean and standard or conjoint analysis utility function goal formulations. Thereby, we show that using the conjoint analysis within a systematic approach to robust concept exploration is well-suited for industrial practice. The systematic approach to robust concept exploration not only yields superior solutions validated by sealing prototypes in wind turbine operation, it also fosters product development efficiency by applying design of experiment and meta-modeling techniques instead of focusing on a more heuristic product development process to achieve sealing designs.
A Classifier-Guided Sampling Method for Computationally Expensive, Discrete-Variable, Discontinuous Design Problems
Authors: Backlund Peter B. , Shahan David W. , Seepersad Carolyn C.
Published: September 2013

Metamodel-based design is a well-established method for providing fast and accurate approximations of expensive computer models to enable faster optimization and rapid design space exploration. Traditionally, a metamodel is developed by fitting a surface to a set of training points that are generated with an expensive computer model or simulation. A requirement of this process is that the function being approximated is continuous. However, many engineering problems have variables that are discrete and a function response that is discontinuous in nature. In this paper, a classifier-guided sampling method is presented that can be used for optimization and design space exploration of expensive computer models that have discrete variables and discontinuous responses. The method is tested on a set of example problems. Results show that the method significantly improves the rate of convergence towards known global optima, on average, when compared to random search.
Toward Considering Risk Attitudes in Engineering Organizations Using Utility Theory
Authors: Van Bossuyt Douglas , Hoyle Chris , Tumer Irem Y. , Dong Andy , Doolen Toni , Malak Richard
Published: September 2013

Design projects within large engineering organizations involve numerous uncertainties that can lead to unacceptably high levels of risk. Practicing designers recognize the existence of risk and commonly are aware of events that raise risk levels. However, a disconnect exists between past project performance and current project execution that limits decision-making. This disconnect is primarily due to a lack of quantitative models that can be used for rational decision-making. Methods and tools used to make decisions in risk-informed design generally use an expected value approach. Research in the psychology domain has shown that decision-makers and stakeholders have domain-specific risk attitudes that often have variations between individuals and between companies. Risk methods used in engineering such as Failure Modes and Effects Analysis (FMEA), Fault Tree Analysis (FTA), and others are often ill-equipped to help stakeholders make decisions based upon risk-tolerant or risk-averse decision-making conditions. This paper focuses on the specific issue of helping stakeholders make decisions under risk-tolerant or risk-averse decision-making conditions and presents a novel method of translating engineering risk data from the domain of expected value into a domain corrected for risk attitude. This is done by using risk utility functions derived from the Engineering-Domain-Specific Risk-Taking (E-DOSPERT) test. This method allows decisions to be made based upon data that is risk attitude corrected. Further, the method uses an aspirational measure of risk attitude as opposed to existing lottery methods of generating utility functions that are based upon past performance. An illustrative test case using a simplified space mission designed in a collaborative design center environment is included. The method is shown to change risk-informed decisions in certain situations where a risk-tolerant or risk-averse decision-maker would likely choose differently than the dictates of the expected value approach.
Dynamic Study of MEMS Variable Capacitive Device for Power Harvesting
Authors: Zhu Jianxiong , Feng Z. C. , Lin Jie , Yuksek Nuh Sadi , Almasri Mahmoud
Published: September 2013

This work shows the complicated dynamic responses of the MEMS parallel plate capacitor for power harvesting resulting from the onset of rocking instability. Rocking instability or symmetry breaking is a relatively new area of study as it pertains to plate instability. It is important because the instability decreases the total amount of power that can be harvested especially when the tips of the moving plate make contact with the fixed plate. Two different designs characterized by the number of variable capacitors are studied. Power harvesting is achieved by the motion of a moving plate under external forces of vibration. The dynamics of the moving plate under sinusoidal excitations are obtained using numerical integration. We show that capacitive plates can become non-parallel due to the onset of rocking instability. Complicated dynamic phenomena including period doubling and chaos can occur. Consequently, the harvested power is greatly reduced when rocking instability occurs.
Concurrent Design Optimization and Calibration-Based Validation Using Local Domains Sized by Bootstrapping
Authors: Drignei Dorin , Mourelatos Zissimos P. , Pandey Vijitashwa , Kokkolaras Michael
Published: September 2013

The design optimization process relies often on computational models for analysis or simulation. These models must be validated to quantify the expected accuracy of the obtained design solutions. It can be argued that validation of computational models in the entire design space is neither affordable nor required. In previous work, motivated by the fact that most numerical optimization algorithms generate a sequence of candidate designs, we proposed a paradigm where design optimization and calibration-based model validation are performed concurrently in a sequence of variable-size local domains that are relatively small compared to the entire design space. A key element of this approach is how to account for variability in test data and model predictions in order to determine the size of the local domains at each stage of the sequential design optimization process. In this paper, we discuss two alternative techniques for accomplishing this: parametric and nonparametric bootstrapping. The parametric bootstrapping assumes a Gaussian distribution for the error between test and model data and uses maximum likelihood estimation to calibrate the prediction model. The nonparametric bootstrapping does not rely on the Gaussian assumption providing therefore, a more general way to size the local domains for applications where distributional assumptions are difficult to verify, or not met at all. If distribution assumptions are met, parametric methods are preferable over nonparametric methods. We use a validation literature benchmark problem to demonstrate the application of the two techniques, emphasizing that results cannot be compared. Which technique to use depends on whether the Gaussian distribution assumption is appropriate based on available information.
Sustainable Design Using Integrated TRIZ and Eco-Checklist With Function Impact Matrix
Authors: Hosseinpour Arash , Peng Qingjin
Published: September 2013

Design is one of the most important stages in product development. Product design has witnessed significant changes during the last few decades in the objective from meeting basic functions to customization. Sustainability is a new concept for assessing product design leading to the low level of adverse impact on environments. This paper examines different methods in sustainable design. A new method, known as integrated TRIZ and Eco-checklist with Function Impact Matrix, is proposed to improve the existing methods. Design of a novel wheelchair is used as an example to apply the proposed method from conceptual design to final design to meet sustainable design outlines. Environmental footprints of product components, including air acidification, energy consumption and carbon footprint, are evaluated in the material selection and manufacturing process.
Towards a Repository of Innovative Products to Enhance Engineering Creativity Education
Authors: Oman Sarah , Gilchrist Brady , Rebhuhn Carrie , Tumer Irem Y. , Nix Anthony , Stone Robert
Published: September 2013

Innovative products are the holy grail for consumer product manufacturers. The essence of what makes a product innovative and in-demand by consumers is a nebulous subject. The research presented in this paper charts the initial steps toward computer-directed innovation in product design. A method for identifying the innovative subsystems in a product and archiving that information is formulated. The innovation information, if archived in a design repository, can support automatic concept generation that is biased toward innovative concepts. Products featured in published lists of innovative products were reverse engineered to expose the component and functional relationships and to analyze where the innovation of the product was most prevalent. A function subtraction method based on difference rewards is used to isolate innovation functions and components in order to populate a Repository of Innovative Products (RIP). The goal behind this research is to develop a method to analyze innovative products such that they may aid in the innovation of future ideas outputted by the Design Repository. This methodology will be used in undergraduate design classes to teach how to factor in creativity and innovation in the early stages of engineering concept design.
Estimating the Orientation of a Game Controller Moving in the Vertical Plane Using Inertial Sensors
Authors: He Peng , Cardou Philippe , Desbiens André
Published: September 2013

This paper presents a novel method of estimating the orientation of a rigid body in the vertical plane from point-acceleration measurements, by discerning its gravitational and inertial components. In this method, a simple stochastic model of the human-hand motions is used in order to distinguish between the two types of acceleration. Two mathematical models of the rigid-body motion are formulated as distinct state-space systems, each corresponding to a proposed method. In both two cases, the output is a nonlinear function of the state, which calls for the application of the extended Kalman filter (EKF). The proposed filter is shown to work efficiently through two simulated trajectories, which are representative of human-hand motions. A comparison of the orientation estimates obtained from the proposed method shows that the filter offers more accuracy than a tilt sensor under high accelerations, and avoids the drift obtained by the time-integration of gyroscope measurements.
Pneumatic Miniature Robot for Laparoendoscopic Single Incision Surgery
Authors: Pourghodrat Abolfazl , Nelson Carl A. , Midday Jeff
Published: September 2013

The transition from open surgery to Laparoendoscopic Single-Site (LESS) surgery to minimize cost and recovery time and improve cosmetic scarring has introduced complexities such as reduced dexterity, restricted workspace, and unintuitive controls. Surgical robotic systems can come into play to address these complexities. The most recent miniature in vivo robots have demonstrated the capability of performing LESS surgery. Since size has been a key driving force for designing these motor-driven robotic platforms, delivering adequate force and torque to perform the surgical tasks has been a primary challenge for improving these robots.

This paper presents a robotic platform actuated primarily by pneumatics, offering the following advantages over motor-driven systems: higher joint torque and tool actuation force, faster actuation, better biocompatibility, better overall robustness, and lower cost. Initially one representative robot joint has been fabricated, to demonstrate the proof of concept and investigate the feasibility of angular position control of the pneumatic joint by deploying a minimal number of electronic components and two low-cost solenoid valves in place of costly fast solenoid valves or expensive servo valves.

The robot design, pneumatic system, implementation of PID and PWM controls, and experimental results are presented.
Designing-In Sustainability by Linking Engineering Curricula With K-12 Science Projects
Authors: Bernstein William Z. , Ramani Arjun , Ruan Xiulin , Ramanujan Devarajan , Ramani Karthik
Published: September 2013

In light of society’s increasing awareness with regards to the health of the environment, many engineering firms are hiring recent engineering graduates with project- (or course-) based experience in environmental sustainability. Currently engineering schools at the collegiate level have addressed this need by modifying their curricula by including additional coursework on sustainability related subjects. The next step of adaptation calls for a holistic treatment of sustainability concepts by integrating them within traditional coursework. Engineering schools have not yet addressed the best way to accomplish this integration due to the concerns stemming from the increase in cognitive load and scheduling pressure. Additionally, it has been shown that K-12 curricula also lack exposure to sustainable thinking. As a result, incoming freshmen are not aware of the inherent correlations between engineering principles, e.g. heat transfer, and environmental sustainability. To prepare the next generation of innovative thinkers to solve these complex, interdisciplinary issues, engineering principles must be contextualized in terms of sustainable design at both the K-12 and undergraduate levels. To meet this need, the authors developed a general framework for introducing sustainable design thinking into K-12 student projects. A pilot case is presented to illustrate a particular student’s (listed as a co-author) growth through a newly gained understanding of environmental sustainability through experimentation. The project specifically addresses various insulation materials for residential buildings by judging their individual environmental advantages and economic feasibility. The main outcome of this project is the extensive redesign of an existing undergraduate heat and mass transfer lab experiment.
A Methodology for the Comprehensive Assessment of International Procurement Costs
Authors: Johnson Michael D. , Sawaya William J. , Natarajarathinam Malini
Published: September 2013

As the economy becomes more globalized and competitive, firms are manufacturing goods in a wider variety of locations. This may be to reduce costs by moving to a low cost country or to place production closer to potential customers. What is often lacking in these decisions is a holistic assessment of the costs associated with production location decisions. Too often the assessment is focused only on a limited set of cost factors (e.g., direct manufacturing and shipping) and does not take into account the dynamic nature of some costs. To address these limitations a comprehensive cost model to assess the cost of procuring goods from alternative locations is presented. A methodology is detailed for monetizing the numerous costs associated with international procurement. An illustrative case study analyzing the procurement of goods from two locations in Mexico and one in the US is detailed. Results of the case show that the non-direct manufacturing costs associated with procurement (e.g., inventory holding costs and shipping) can be greater than direct manufacturing costs. The effects of fuel and labor cost sensitively on the alternative locations is also detailed.
An Approach for Revealed Consumer Preferences for Technology Products: A Case Study of Residential Solar Panels
Authors: Chen Heidi Q. , Honda Tomonori , Yang Maria C.
Published: September 2013

Consumer preferences can serve as an effective basis for determining key product attributes necessary for market success, allowing firms to optimally allocate time and resources toward the development of these critical attributes. However, identification of consumer preferences can be challenging, particularly for technology-push products that are still early on in the technology diffusion S-curve, which need an additional push to appeal to the early majority. This paper presents a method for revealing preferences from actual market data and technical specifications. The approach is explored using three machine learning methods: Artificial Neural Networks, Random Forest decision trees, and Gradient Boosted regression applied on the residential photovoltaic panel industry in California, USA. Residential solar photovoltaic installation data over a period of 5 years from 2007–2011 obtained from the California Solar Initiative is analyzed, and 3 critical attributes are extracted from a pool of 34 technical attributes obtained from panel specification sheets. The work shows that machine learning methods, when used carefully, can be an inexpensive and effective method of revealing consumer preferences and guiding design priorities.
Effects of Voltage and Distance on Stand-Alone Lance Electrodes During Repulsion
Authors: Toone Nathan C. , Jensen Brian D.
Published: September 2013

This paper explores the effects of two parameters—operation voltage and the distance between the lance and electrode—on the repulsion process of a Stand-Alone Lance, a second-generation Nanoinjection tool used to inject DNA into egg cells for genetic purposes. Using a mathematical computer model to simulate the motion of the DNA during repulsion from the lance and into the cell, the results are quantified by the average DNA travel time and the electric field strength, which relates to the electroporation envelope. It is found that voltage has a very strong effect, while changing distance yields much less dramatic results. Specific ideal values are recommended for the magnitude and duration of the voltage pulse to successfully repel DNA into the cell.
Adaptive Orthonormal Basis Functions for High Dimensional Metamodeling With Existing Sample Points
Authors: Haji Hajikolaei Kambiz , Wang G. Gary
Published: September 2013

High Dimensional Model Representation (HDMR) is a tool for generating an approximation of an input-output model for a multivariate function. It can be used to model a black-box function for metamodel-based optimization. Recently the authors’ team has developed a radial basis function based HDMR (RBF-HDMR) model that can efficiently model a high dimensional black-box function and, moreover, to uncover inner variable structures of the black-box function. This approach, however, requests a complete new, although optimized, set of sample points, as dictated by the methodology, while in engineering design practice one often has many existing sample data. How to utilize the existing data to efficiently construct a HDMR model is the focus of this paper. We first identify the Random-Sampling HDMR (RS-HDMR), which uses orthonormal basis functions as HDMR component functions and existing sample points can be used to calculate the coefficients of the basis functions. One of the important issues related to the RS-HDMR is that in theory the basis functions are obtained based on the continuous integrations related to the orthonormality conditions. In practice, however, the integrations are approximated by Monte Carlo summation and thus the basis functions may not satisfy the orthonormality conditions. In this paper, we propose new and adaptive orthonormal basis functions with respect to a given set of sample points for RS-HDMR approximation. RS-HDMR models are built for different test functions using the standard and new adaptive basis functions for different number of sample points. The relative errors for both models are calculated and compared. The results show that the models that are built using the new basis functions are more accurate.
Evaluation of Network Measures as Complexity Metrics
Authors: Singh Gurpreet , Balaji Srinath , Shah Jami J. , Corman David , Howard Ron , Mattikalli Raju , Stuart D.
Published: September 2013

Modern automotive and aerospace products are large cyber-physical system consisting of software, mechanical, electrical and electronic components. The increasing complexity of such systems is a major concern as it impacts development time and effort, as well as, initial and operational costs. Although much literature exists on complexity metrics, very little work has been done in determining if metrics correlate with real world products. Aspects of complexity include the product structure, development process and manufacturing. Since all these aspects can be uniformly represented in the form of networks, we examine common network based complexity measures in this paper. Network metrics are grouped into three categories: size complexity, numeric complexity (degree of coupling) and technological complexity (solvability). Several empirical studies were undertaken to determine the efficacy of various metrics. One approach was to survey project engineers in an aerospace company to gauge their perception of complexity. The second was through case studies of alternative designs to perform equivalent functions. The third was to look at actual time, labor data from past projects. Data structures and fast algorithms for complexity calculations for large cyber physical systems were also implemented.
Linear Control Techniques Applied to the Omnicopter MAV in Fixed Vertical Ducted Fan Angle Configuration
Authors: Long Yangbo , Lyttle Sean , Cappelleri David J.
Published: September 2013

In this paper, linear control techniques are applied to a novel Omnicopter MAV design. This design is unique in its ability to withstand external disturbance and translate horizontally with more stable attitude. A dynamic model of the Omnicopter MAV has been developed using the Newton-Euler formalism. Based on a linearized version of the model with a fixed vertical ducted fan angle configuration, three different control schemes, namely PD control, Lyapunov-based control and optimal LQ control have been designed and proposed. Comparisons and relations between the three control schemes are discussed and simulations are presented. Finally, details on the Omnicopter prototype and initial test flights are presented. Controlled flights with vertical take-offs and landings have been achieved utilizing the PD control scheme.
Nonlinear Dynamics of a NEMS Carbon Nanotube Resonator
Authors: Ruzziconi Laura , Younis Mohammad I. , Lenci Stefano
Published: September 2013

In this study we consider a slacked CNT and analyze the nonlinear response under electrostatic and electrodynamic actuation. We introduce a reduced-order model, which takes into account the single-mode dynamics and is derived via the Ritz method and the Padé approximation. The overall scenario of the device behavior is investigated when both the frequency and the electrodynamic voltage are varying. Extensive numerical simulations are performed by the combined use of frequency response diagrams, attractor-basins phase portraits, and frequency-dynamic voltage behavior chart. Our aim is that of illustrating the richness of the nonlinear events that may undergo in the device due to the coupling of mechanical and electrical nonlinearities. We observe that the CNT exhibits coexisting competing attractors, which lead to a versatile behavior. We examine the multistability in detail. The response is explored not only at low electrodynamic voltages, where the safe jump between attractors is ensured, but also at large electrodynamic excitation, where the inevitable escape (dynamic pull-in) becomes impending. We detect the theoretical boundaries of appearance and disappearance of the main attractors, which provide a complete description of the response.
Exploration of the Use of Design Methods With the Design Structure Matrix for Integrating New Technologies Into Large Complex Systems
Authors: Alzaharnah Iyad T. , Seering Warren P. , Yang Maria C.
Published: September 2013

Integrating products of basic technology research and development efforts into Large Complex Systems (LCSs) requires systematic approaches. It has been observed that because of the complexity associated with LCSs, no single structured design method will suffice for integrating new technologies into an LCS. In this work, we explore through the literature how an integrated design approach involving the Design Structure Matrix (DSM) with several design methods (mainly those involving other matrix-based methods) might support the introduction of new technologies into large complex facilities. The survey presented in the paper could provide support for future investigations on how to align the outcomes of R&D processes with the requirements of introducing new technologies in target LCSs. Also it could help in developing future understandings about transitioning basic outcomes of R&D into technology products and services.
Example of Internal Redundancy to Improve the Dynamics Performance of Parallel Manipulators
Authors: Parsa Soheil S. , Carretero Juan A. , Boudreau Roger
Published: September 2013

In recent years, redundancy in parallel manipulators has been discussed for the cases of kinematic, actuation and branch redundancy. Some advantages of these redundant manipulators include the reduction or elimination of some types of kinematic singularities and/or an increase of their reachable and dexterous workspaces, to name a few. Internal redundancy, first introduced for serial manipulators, refers to the concept of adding movable masses to some links so as to allow to control the center of mass and other dynamic properties of some links. In this paper, the concept of internal redundancy is investigated for the first time in the context of parallel manipulators. More specifically, the 3-RRR planar manipulator, where a movable mass has been added to the distal link, is analysed. The manipulator’s dynamic model is briefly introduced and then is used to track a simple trajectory. A numerical example is shown to support the idea.
The Effects of Curved Foot Design Parameters on Planar Biped Walking
Authors: Martin Anne E. , Schmiedeler James P.
Published: September 2013

Although the nature of their gaits is similar, planar bipeds with curved feet have been shown experimentally to be more energetically efficient than those with point feet. Further, both healthy human feet and prosthetic feet can be modeled as a circular arc with the center of curvature in front of the shank. Thus, understanding the effects of a curved foot’s properties on the energetic cost of gait and on gait kinematics has the potential to improve both bipedal robots and prosthesis design. To date, there has not been a systematic study of the effects of changing the foot radius and center of curvature location on symmetric bipeds. This paper explores the effects of changing the curved foot’s geometric properties for both two- and five-link planar, underactuated bipeds with instantaneous transfer of support at impact. It is found that the foot radius has a substantial effect on the energetic efficiency of a gait regardless of the morphology of the biped. The effect of foot center of curvature location on energy efficiency is dependent on the morphology of the biped and is much less significant than the effect of foot radius. Both the foot radius and center of curvature location affect the knee kinematics of the five-link biped. The foot radius affects the hip kinematics of the two-link biped.
Stick-Slip Dynamics in Ultrasonic Additive Manufacturing
Authors: Gibert James M. , Fadel Georges M. , Daqaq Mohammed F.
Published: September 2013

Ultrasonic Additive Manufacturing is a solid state manufacturing process that combines ultrasonic welding of layers of thin metal foil with contour milling. Bonding between two foils is accomplished by holding the foils together under pressure and applying high-frequency excitations normal to the pressure direction. The accepted explanation for bonding is that stresses due to both compression and friction stemming from the interfacial motion between the foils result in plasticity and ultimately produce a metallurgical bond. The process however, has been shown to have a critical shortcoming in its operation; namely, the presence of a range of build heights within which bonding cannot be initiated. To better understand the reasons for this anomaly, this paper simplifies the process into a lumped parameter dry friction oscillator and shows that complex stick-slip motions of the build feature near or above its resonance frequency may explain bond degradation. Specifically, it is shown through bifurcation maps obtained for different process parameters that, at the critical build heights, the feature exhibits pure stick motions due to primary resonant interactions between the external excitation and the feature. Furthermore, complex aperiodic responses are observed at build heights above resonance (short features). In such scenarios, bonding cannot be initiated because no or non-uniform interfacial motions occur between the tape and the feature. It is also observed that, once the height of the build feature increases beyond the critical value corresponding to resonance, periodic uniform responses essential for bonding, are recovered. These results corroborates previous experimental findings which demonstrate that bonding can be hard to initiate near or slightly above resonance (at or slightly below a critical height) but can be reinitiated below resonance (above the critical height).
Design Methodology for the CSM HAN-DS Gripper
Authors: Streusand David B. , Turner Cameron J.
Published: September 2013

This paper describes the application of classical design methodology toward the design of a robotic gripper. This gripper is designed to meet or exceed the mechanical properties of the BarrettHand for a lower cost. The design process followed a classical design process as previously introduced by Streusand and Turner with some modifications due working as an individual rather than as a design team member. This process proved effective in the design of the gripper, though there are some recommendations for improving the method and some improvements need to be made to the current gripper design before it is ready for use.
Design for Micro Insert Moulding: A Review
Authors: Farrugia P. , Vella P. , Said Luke
Published: September 2013

Nowadays micro technologies are constantly increasing in importance due to the rapid growth of their respective applications. Recent works have investigated the potential of multi material micro fabrication technologies. One of the most cost efficient polymer micro fabrication technologies is injection moulding. Such cost effectiveness arises due to the reusability of a micro mould cavity. A process variant of multi material micro injection moulding is insert moulding. This paper characterizes the process of micro injection moulding in general and contributes a review of the state-of-the-art research studies together with technologies relevant specifically to micro insert injection moulding. From the literature review a research gap has been identified, namely that designers and process engineers lack support in the form of guidelines to develop micro multi-material components by insert moulding. Research directions are recommended to address this gap. These include methods to generate and formalize design and manufacturing guidelines for micro insert moulding.
Robust Optimization of Mixed-Integer Problems Using NURBs-Based Metamodels
Authors: Steuben John C. , Turner Cameron J.
Published: September 2013

The optimization of mixed-integer problems is a classic problem with many industrial and design applications. A number of algorithms exist for the numerical optimization of these problems, but the robust optimization of mixed-integer problems has been explored to a far lesser extent. We present here a general methodology for the robust optimization of mixed-integer problems using Non Uniform Rational B-spline (NURBs)-based metamodels and graph theory concepts. The use of these techniques allows for a new and powerful definition of robustness along integer variables. In this work, we define robustness as an invariance in problem structure, as opposed to insensitivity in the dependent variables. The application of this approach is demonstrated on two test problems. We conclude with a performance analysis of our new approach, comparisons to existing approaches, and our views on the future development of this technique.
Mixed-Dimensional Model Analysis Under Dimension Reduction Error Control
Authors: Tang Jianguo , Gao Shuming , Li Ming , Qin Feiwei
Published: September 2013

In order to conduct engineering analysis efficiently, complex CAD model is generally idealized by dimension reduction of its local thin regions into mid-surfaces, which results in a mixed-dimensional model. However, such dimension reduction inevitably induces analysis errors when plate or shell theory applied to the mixed-dimensional model.

In this paper, an evaluation indicator is proposed for estimating analysis error induced by dimension reduction of a original model into mixed-dimensional model and used to control the analysis results of the mixed-dimensional model with given accuracy. The evaluation indicator is defined as the stress difference on the coupling interface between the mixed-dimensional model and the original model. When the mixed-dimensional model is analyzed, p-version solid elements were generated by offsetting the shell nodes in the thickness direction. Moreover, element stiffness matrix, boundary conditions and material properties can be extracted from the analysis results and reused for the indicator computation. Displacements of the mixed-dimensional model are input as initial value to iterative solver to accelerate the computation. When the indicator is below the accuracy, final analysis can be proceeded with p-adaptivity in the thin regions. The hierarchical shape function for p-version solid elements ensures the efficiency of the error estimation and the reliability of the final analysis. The robustness of the evaluation indicator and computational efficiency for final analysis are illustrated by experiments on engineering models.