bluuebunny/crossref_metadata_2025 huggingface dataset:
Functional Impact Comparison of Common and Innovative Products
Authors: Gilchrist Brady , Van Bossuyt Douglas L. , Tumer Irem Y. , Arlitt Ryan , Stone Robert B. , Haapala Karl R.
Published: February 2014

Innovation has been touted as a means toward providing sustainability. Innovations in materials, manufacturing, and product design can lead to a reduction of global environmental impacts while helping to realize the goals of a sustainable society. This research aims to explore whether or not product functionality has an effect on environmental impact and if the flow of energy, materials, and signals (EMS) have an effect on product environmental impact. Innovative and common products are identified and life cycle assessment is performed for each product at the component level. Using function impact matrices, the environmental impacts of the product components are propagated back to the functional level, where their impacts are compared. The innovative products of the comparisons conducted appear to be more environmentally impact; more work must be done to understand whether the result is generalizable. The intended use of this research is during the conceptual design phase when little is known about the final form of a product. With approximate impacts of functions known, designers can better utilize their design efforts to reduce overall product environmental impact.
Wave Energy Extraction Maximization in Irregular Ocean Waves Using Pseudospectral Methods
Authors: Herber Daniel R. , Allison James T.
Published: February 2014

Energy extraction from ocean waves and conversion to electrical energy is a promising form of renewable energy, yet achieving economic viability of wave energy converters (WECs) has proven challenging. In this article, the design of a heaving cylinder WEC will be explored. The optimal plant (i.e. draft and radius) design space with respect to the design’s optimal control (i.e. power take-off trajectory) for maximum energy production is characterized. Irregular waves based on the Bretschneider wave spectrum are considered. The optimization problem was solved using a pseudospectral method, a direct optimal control approach that can incorporate practical design constraints, such as power flow, actuation force, and slamming. The results provide early-stage guidelines for WEC design. Results show the resonance frequency required for optimal energy production with a regular wave is quite different than the resonance frequency found for irregular waves; specifically, it is much higher.
A Maximum Confidence Enhancement Based Sequential Sampling Scheme for Simulation-Based Design
Authors: Wang Zequn , Wang Pingfeng
Published: February 2014

This paper presents a maximum confidence enhancement based sequential sampling approach for simulation-based design under uncertainty. In the proposed approach, the ordinary Kriging method is adopted to construct surrogate models for all constraints and thus Monte Carlo simulation (MCS) is able to be used to estimate reliability and its sensitivity with respect to design variables. A cumulative confidence level is defined to quantify the accuracy of reliability estimation using MCS based on the Kriging models. To improve the efficiency of proposed approach, a maximum confidence enhancement based sequential sampling scheme is developed to update the Kriging models based on the maximum improvement of the defined cumulative confidence level, in which a sample that produces the largest improvement of the cumulative confidence level is selected to update the surrogate models. Moreover, a new design sensitivity estimation approach based upon constructed Kriging models is developed to estimate the reliability sensitivity information with respect to design variables without incurring any extra function evaluations. This enables to compute smooth sensitivity values and thus greatly enhances the efficiency and robustness of the design optimization process. Two case studies are used to demonstrate the proposed methodology.
An Investigation Into the Effects of Curved Beam Elements on the Out-of-Plane Stiffness Profile in a Compliant Large-Displacement Finger
Authors: Goemans Valerie Y. , Herder Just L. , Frecker Mary I.
Published: February 2014

Compliant mechanisms have many advantages over rigid-link mechanisms. However, one of the challenges of compliant mechanisms is the trade-off between a large range of motion and a high out-of-plane stiffness. Furthermore, the out-of-plane stiffness is shown to vary over the range of motion. Especially for large-displacement compliant mechanisms this can be by a significant amount. In this paper the use of curved beam elements in a compliant mechanism is shown to have impact on this trade-off. The influence of curved beam elements on the out-of-plane stiffness over the entire range of motion is presented for simple structures such as a single beam element and double beam elements, as well as a compliant finger. With the use of a genetic algorithm optimization, the difference in performance of a design with only straight beam elements versus one with curved beam elements is highlighted and the effect on the out-of-plane stiffness profile is presented. The optimization with curved beam elements results in solutions with a performance in terms of objective function values that cannot be found by the optimization with only straight beam elements. It is shown that for simple structures the use of curved beam elements has a large influence on the shape of the out-of-plane stiffness profile along the range of motion, while for the compliant finger the influence is mainly in the variables of the out-of-plane stiffness profile.
Impact of Model-Based Design in Engineering Design Education
Authors: Andersson Kjell
Published: February 2014

Project-based education in combination with problem-based learning has been very successful, and has contributed to the popularity of engineering design among students at technical universities. And when the project work addresses real industrial problems, offers insight into post-graduation working environments and gets direct feedback from professionals in industry, students can see the immediate relevance of their education — an invaluable boost to their learning experience.

Students taking MF2004, a capstone course at KTH Department of Machine Design, learn the whole process from idea generation to manufacturing and testing a final prototype built in close collaboration with an industrial partner or a research group at the department. The benefits of using real prototypes cannot be stressed enough — students find out for themselves why a product must be designed in a certain way (e.g. to make it possible to assemble). The course uses project-based learning as a teaching strategy and introduces a model-based design methodology which enables the students to evaluate and “experience” many different behaviors of the product using digital models in a virtual environment. In this way, students can see that many undesirable concepts and flaws can be avoided even before a prototype is manufactured.

This paper focuses on the introduction of the model-based design methodology and evaluation of its impact on learning in a capstone course in the Engineering Design MSc programme at KTH Department of Machine Design. A questionnaire was used to evaluate the effects on the students’ learning, as well as to assess how feasible they consider this methodology to be. On the basis of this, in combination with the weekly meetings with the project teams, we can report a positive attitude among the students and improved learning outcomes.
Impacts of Team Composition of Distance and On-Campus Students on the Conceptual Design Performance
Authors: Liu Ang , Lu Stephen C.-Y.
Published: February 2014

In light of the rapid development of distance education, the distributed project teams that consist of both distance and on-campus students are becoming increasingly popular in many engineering design courses. This study examines different types of distributed design teams in terms of their collective ideation effectiveness. Depending on the distribution scale, various design teams can be classified into three types: collocated, partially distributed, and fully distributed teams. Furthermore, depending on the distribution distance, the distributed teams can be further categorized into “far” and “near” distributed teams. In this study, we evaluate and compare the ideation effectiveness of 24 team design in terms of the metrics of quantity, variety, quality and novelty. The results indicate that, compared to the fully distributed teams, both collocated and partially distributed teams demonstrate better ideation performance but in different metrics. The “far” distributed teams have a significantly better performance than the “near” distributed teams in terms of variety.
Motion Capture for Human-Centered Simulation Using Kinects
Authors: Daphalapurkar Chinmay P. , Zhu Wenjuan , Leu Ming C. , Liu Xiaoqing F. , Chang Alpha M. , Gilpin-Mcminn J. K. , Wu P. H. , Snodgrass S. D.
Published: February 2014

Microsoft Kinect is capable of tracking human movements and can be used to develop various human-centered simulations. It is very attractive for certain applications because it is a low-cost, marker-less device. This paper presents our research toward characterizing the accuracy of Kinect and developing Kinect-based motion capture systems. Besides a single-Kinect system, a motion capture system with multiple Kinects were developed in order to increase the tracking volume and to improve the simulation fidelity. A motor-driven shutter mechanism was developed for use with each Kinect for the multi-Kinect system to address the issue of interference on the infrared light pattern without lowering the frame rate. The capabilities of the developed Kinect-based motion capture systems are demonstrated by tracking a human in performing a fastening operation on an aircraft fuselage mockup.
The Closed-Form Equation of Motion of a Human Body With Joint Friction
Authors: Huang Qingmin , Chen Ye-Hwa , Nie Xin
Published: February 2014

A general method for equation of motion of a human body is presented. The equation is in closed-form (i.e., analytic form). A hierarchical approach is introduced to get the equation of motion of the human body. The constraint force between subsystems is explicitly obtained which can be used to calculate the joint friction torque. The final equation of motion includes the dynamics of the unconstrained motion, the constraints, and the constraint forces including the joint friction torque induced by the nonideal constraints. No auxiliary variables such as Lagrange multipliers or pseudo-generalized speeds are needed. Therefore the equation of motion is most suitable for generic dynamic analysis and control design. A four-segment, planar, articulated linkage free fall human body is chosen to demonstrate this method.
A Heat Transfer Model for the Conceptual Design of a Biomass Cookstove for Developing Countries
Authors: MacCarty Nordica , Bryden Kenneth M.
Published: February 2014

The use of biomass cookstoves to meet household energy needs has a profound impact on the life and health of individuals, families, and communities in the developing world. This paper introduces an experimentally validated heat transfer analysis model for use during the conceptual design process of a biomass cookstove to be used in the developing world. This steady-state model of a shielded, natural-draft biomass cookstove fitted with a flat-bottomed pot with pot-shield was developed using published experimental data that included 63 variations of 15 operating, geometrical, and material variables. The model provides the essential information needed to support decision making during the cookstove conceptual design process by predicting heat transfer efficiency as a function of stove geometry, construction material, firepower, and fuel moisture content.
Fad or Here to Stay: Predicting Product Market Adoption and Longevity Using Large Scale, Social Media Data
Authors: Tuarob Suppawong , Tucker Conrad S.
Published: February 2014

The authors of this work propose a Knowledge Discovery in Databases (KDD) model for predicting product market adoption and longevity using large scale, social media data. Social media data, available through sites such as Twitter® and Facebook®, have been shown to be leading indicators and predictors of events ranging from influenza spread, financial stock market prices, and movie revenues. Being ubiquitous and colloquial in nature allows users to honestly express their opinions in a unified, dynamic manner. This makes social media a relatively new data gathering source that can potentially appeal to designers and enterprise decision makers aiming to understand consumers response to their upcoming/newly launched products. Existing design methodologies for leveraging large scale data have traditionally relied on product reviews available on the internet to mine product information. However, such web reviews often come from disparate sources, making the aggregation and knowledge discovery process quite cumbersome, especially reviews for poorly received products. Furthermore, such web reviews have not been shown to be strong indicators of new product market adoption. In this paper, the authors demonstrate how social media can be used to predict and mine information relating to product features, product competition and market adoption. In particular, the authors analyze the sentiment in tweets and use the results to predict product sales. The authors present a mathematical model that can quantify the correlations between social media sentiment and product market adoption in an effort to compute the ability to stay in the market of individual products. The proposed technique involves computing the Subjectivity, Polarity, and Favorability of the product. Finally, the authors utilize Information Retrieval techniques to mine users’ opinions about strong, weak, and controversial features of a given product model. The authors evaluate their approaches using the real-world smartphone data, which are obtained from www.statista.com and www.gsmarena.com.
Development of a Common Platform for Testing Metamodel Based Design Optimization Methods
Authors: Younis Adel A. , Cheng George H. , Wang G. Gary , Dong Zuomin
Published: February 2014

Metamodel based design optimization (MBDO) algorithms have attracted considerable interests in recent years due to their special capability in dealing with complex optimization problems with computationally expensive objective and constraint functions and local optima. Conventional unimodal-based optimization algorithms and stochastic global optimization algorithms either miss the global optimum frequently or require unacceptable computation time. In this work, a generic testbed/platform for evaluating various MBDO algorithms has been introduced. The purpose of the platform is to facilitate quantitative comparison of different MBDO algorithms using standard test problems, test procedures, and test outputs, as well as to improve the efficiency of new algorithm testing and improvement. The platform consists of a comprehensive test function database that contains about 100 benchmark functions and engineering problems. The testbed accepts any optimization algorithm to be tested, and only requires minor modifications to meet the test-bed requirements.

The testbed is useful in comparing the performance of competing algorithms through execution of same problems. It allows researchers and practitioners to test and choose the most suitable optimization tool for their specific needs. It also helps to increase confidence and reliability of the newly developed MBDO tools. Many new MBDO algorithms, including Mode Pursuing Sampling (MPS), Pareto Set Pursuing (PSP), and Space Exploration and Unimodal Region Elimination (SEUMRE), were tested in this work to demonstrate its functionality and benefits.
Improved Trust Region Based MPS Method for High-Dimensional Expensive Black-Box Problems
Authors: Cheng George H. , Younis Adel , Hajikolaei Kambiz Haji , Wang G. Gary
Published: February 2014

Mode Pursuing Sampling (MPS) was developed as a global optimization algorithm for optimization problems involving expensive black box functions. MPS has been found to be effective and efficient for problems of low dimensionality, i.e., the number of design variables is less than ten. A previous conference publication integrated the concept of trust regions into the MPS framework to create a new algorithm, TRMPS, which dramatically improved performance and efficiency for high dimensional problems. However, although TRMPS performed better than MPS, it was unproven against other established algorithms such as GA. This paper introduces an improved algorithm, TRMPS2, which incorporates guided sampling and low function value criterion to further improve algorithm performance for high dimensional problems. TRMPS2 is benchmarked against MPS and GA using a suite of test problems. The results show that TRMPS2 performs better than MPS and GA on average for high dimensional, expensive, and black box (HEB) problems.
SDRE Control Applied to an Electromechanical Pendulum Excited by a Non-Ideal Motor
Authors: Bueno Atila Madureira , Tusset Angelo Marcelo , dos Santos João Paulo Martins , Tsuchida Masayoshi , Balthazar José Manuel
Published: February 2014

The dynamical behavior of an electromechanical pendulum system is analyzed by means of the classical perturbation theory. A frequency response model of the system is obtained, and the number of unstable poles are determined with the Routh-Hurwitz criterion. Numerical simulations show that the system presents nonlinear behavior such as hysteresis, with hard and soft characteristics, and the Sommerfeld effect in the resonance region. In order to keep the oscillations of the electromechanical system in a pre-defined amplitude range a control strategy is designed. The SDRE control strategy is used considering two control signals, a feedback control that tracks the system to a desired periodic orbit, and a nonlinear feedforward control that holds the system to that desired periodic orbit. Additionally, the robustness of the control technique is tested for parametric uncertainties. Numerical simulations show the efficiency of the control strategy.
Using Planar Kinematics to Construct the Full 4-D Tolerance-Map for a Line-Profile
Authors: Savaliya S. B. , Davidson J. K. , Shah Jami J.
Published: February 2014

Tolerances on line-profiles are used to control cross-sectional shapes of parts, even mildly twisted ones such as those on turbine or compressor blades. Such tolerances limit geometric manufacturing variations to a specified two-dimensional tolerance-zone, i.e. an area, the boundaries to which are curves parallel to the true profile. The single profile tolerance may be used to control position, orientation, and form of the profile.

For purposes of automating the assignment of tolerances during design, a math model, called the Tolerance-Map (T-Map), has been produced for most of the tolerance classes that are used by designers. Each T-Map is a hypothetical point-space that represents the geometric variations of a feature in its tolerance-zone. Of the six tolerance classes defined in the ASME/ANSI/ISO Standards, only one attempt has been made at modeling line-profiles [1], and the method used is a kinematic description, based largely on intuition, of the allowable displacements of the middle-sized profile within its tolerance-zone. The result presented is a 4-D double pyramid having a 3-D shape for the common base. Allowable small changes in size represent the fourth dimension in the altitude-direction of the pyramids. However, that work is limited to square, rectangular, and right-triangular profile shapes for which the 3-D transverse sections (called hypersections) of the 4-D T-Map are all geometrically similar to the base because the boundaries are doubly traced. For more generally shaped profiles, [2] the hypersections are not geometrically similar to the base.

The objective of this paper is to expand the kinematic description of a profile in its tolerance-zone to include the changing constraints that take place as size is incremented or decremented within the allowable tolerance-range. It provides validation of a different method that is described in a companion paper [3].
Diagnosis and Prognosis of AH64D Tail Rotor Gearbox Bearing Degradation
Authors: Lim Reuben , Mba David
Published: February 2014

Most research work has been performed within laboratory environments with seeded defects or accelerated testing and there is little published in the public domain on in-service defects with operational helicopter HUMS data. This study focuses on the actual service experience gathered from HUMS equipped AH64D helicopter belonging to the Republic of Singapore Air Force. Operational HUMS data from three helicopters with similar in-service defects found on their Tail Rotor Gearbox are analyzed and correlated with tear-down inspection findings. From analysis of the HUMS vibration spectrum, fault patterns which show the progression from localised to generalised damage in the bearing can be observed consistently across the defective gearboxes. The observed fault patterns are extracted as Condition Indicators (CI) to diagnose the different stages of bearing degradation within the gearbox. As the defects between the gearboxes are similar, the historical trends of the extracted CIs are used to developed prognostic model using parameter estimation approach.
Reconstructing David Huffman’s Origami Tessellations
Authors: Davis Eli , Demaine Erik D. , Demaine Martin L. , Ramseyer Jennifer
Published: February 2014

David A. Huffman (1925–1999) is best known in computer science for his work in information theory, particularly Huffman codes, and best known in origami as a pioneer of curved-crease folding. But during his early paper folding in the 1970s, he designed and folded over a hundred different straight-crease origami tessellations. Unlike most origami tessellations designed in the past twenty years, Huffman’s straight-crease tessellations are mostly three-dimensional, rigidly foldable, and have no locking mechanism. In collaboration with Huffman’s family, our goal is to document all of his designs by reverse-engineering his models into the corresponding crease patterns, or in some cases, matching his models with his sketches of crease patterns. Here we describe several of Huffman’s origami tessellations that are most interesting historically, mathematically, and artistically.
A Bayesian Approach to Extrinsic Versus Intrinsic Uncertainty in Design for Market Systems
Authors: Frischknecht Bart D.
Published: February 2014

This article illustrates how variance in the predictive distribution of the profit objective function in a design for market systems model can be decomposed into two components using a simulation based Bayesian approach introduced in the econometrics literature. The first component, intrinsic uncertainty, would be retained in the model even if the model calibration parameter values, such as parameters representing customer preferences, were known with certainty. The second component, extrinsic uncertainty, stems from lack of precision regarding model calibration parameters such as customer preferences. The simulation based approach overcomes a key problem in decomposing uncertainty for the typical design for market systems problem by overcoming the difficulties associated with analytical treatment of non-normal distributions. The variance decomposition approach is demonstrated for the design of a handheld grinder power tool. Following the same Bayesian decision analysis framework the variance simulation method can be applied to other design for market system problems with other objective functions and with additional sources of uncertainty.
Application of Conformal Maps to Origami-Based Structures: New Method to Design Deployable Circular Membranes
Authors: Ishida Sachiko , Nojima Taketoshi , Hagiwara Ichiro
Published: February 2014

This paper presents a new method using conformal transformation to design crease patterns of circular membranes that can be wrapped up compactly. This method is focused on the advantages of origami that are packaged compactly and deployable at will, and enables to design complex deployable structures systematically and efficiently from simple structures, controlling angles among fold lines. Various deployable circular membranes are successfully produced by the method. They are wrapped up around the center of membranes and form structures such as regular polygons, rectangles, diamond shapes, etc. Circular membranes with zigzag fold lines to radial direction are also demonstrated. They are deployable along radial direction of membranes. The proposed method is flexible to generate zigzag fold lines, compared with the method by mirror image, since zigzag fold lines can be designed close to the center of membranes without geometrical constraints. For industrial application, models made of a plastic film, closing and a stainless steel plate are also demonstrated.
Modeling Contact Accurately Using Localized Enrichment
Authors: Tupsakhare Anand S. , Nagarajan Venkatram , Kumar AshokV.
Published: February 2014

Traditional finite element method requires very high density mesh and nonlinear analysis to obtain reasonably accurate solutions for elastic contact problems. Analytical solutions are available for these problems based on Hertz theory of elastic contact. In this paper we show that using implicit boundary approach, solutions that are of similar accuracy can be obtained without the need for nonlinear analysis. This approach is applied here only for tied contacts so that there is no sliding or separation. Contacting bodies are modeled as an assembly of parts and a separate background mesh is constructed for each part. At the contact, elements of the mesh belonging to the contacting parts overlap. A trial function is constructed such that the displacements are continuous at the contact. The goal is to capture the stresses as accurately as possible using sufficiently dense global mesh. Several elastic contact problems including classical point and line contact problems are used to study the effectiveness of this approach.
Eye-Tracking Data Predicts Importance of Product Features and Saliency of Size Change
Authors: Du Ping , MacDonald Erin F.
Published: February 2014

Features, or visible product attributes, are indispensable product components that influence customer evaluations of functionality, usability, symbolic impressions and other qualities. Two basic components of features are visual appearance and size. This work tests whether or not eye-tracking data can (1) predict the relative importances between features, with respect to their visual design, in overall customer preference; and (2) identify how much a feature must change in size in order to be noticeable by the viewer. The results demonstrate that feature importance is significantly correlated with a variety of gaze data. Results also show that there are significant differences in fixation time and count for noticeable vs. unnoticeable size changes. Logistic models of gaze data can predict both feature importance and saliency of size change.
Dynamic Response of an Unbalanced Rotor Supported on Bearing With Outer Race Waviness
Authors: Kankar P. K. , Sharma Satish C. , Harsha S. P.
Published: February 2014

The paper investigates the non-linear dynamic response of an unbalanced rotor supported on ball bearings with outer race waviness. The excitation is due to unbalanced force and waviness on outer race. The sources of non-linearities are both the radial clearance as well as the Hertzian contact between races and rolling elements. The nonlinear responses due to unbalanced rotor supported on bearings are investigated. The combined effects like non-linear stiffness and non-linear damping for unbalanced rotor with bearing waviness have been considered and analyzed in detail for a rotor bearing system. In the mathematical formulation, the contacts between the rolling elements and the races are considered as an oscillating spring-mass-damper system. The appearance of regions of periodic, sub-harmonic and chaotic behavior is seen to be strongly dependent on the number of waves in the outer race. The results show the appearance of instability and chaos in the dynamic response as the number of waves in the outer race is changed. The study indicates that the interaction of ball passage frequency (ωbp) due to outer race waviness and rotational frequency (X) due to the unbalanced rotor force. Poincaré maps and frequency responses are used to elucidate and to illustrate the diversity of the system behavior.
Simulating Stochastic Diffusions by Quantum Walks
Authors: Wang Yan
Published: February 2014

Stochastic differential equation (SDE) and Fokker-Planck equation (FPE) are two general approaches to describe the stochastic drift-diffusion processes. Solving SDEs relies on the Monte Carlo samplings of individual system trajectory, whereas FPEs describe the time evolution of overall distributions via path integral alike methods. The large state space and required small step size are the major challenges of computational efficiency in solving FPE numerically. In this paper, a generic continuous-time quantum walk formulation is developed to simulate stochastic diffusion processes. Stochastic diffusion in one-dimensional state space is modeled as the dynamics of an imaginary-time quantum system. The proposed quantum computational approach also drastically accelerates the path integrals with large step sizes. The new approach is compared with the traditional path integral method and the Monte Carlo trajectory sampling.
Measurement of Robot Link Joint Parameters Using Multiple Accelerometers and Gyroscope
Authors: Vikas Vishesh , Crane Carl D.
Published: February 2014

A novel approach of dynamic, non-contact measurement of joint parameters using the planar Vestibular Dynamic Inclinometer (pVDI) is proposed in this paper. The gravity-invariant planar Vestibular Dynamic Inclinometer (pVDI) is a non-contact sensor that consists of symmetrically placed four dual-axis accelerometers and one tri-axial gyroscope. The deployment of the non-contact sensor is strategic and need not be at the joints. The paper proposes measurement of joint parameters — base angle, joint angle, angular velocity and angular acceleration, that are independent of integration errors/drift.
Manufacture of Arbitrary Cross-Section Composite Honeycomb Cores Based on Origami Techniques
Authors: Saito Kazuya , Pellegrino Sergio , Nojima Taketoshi
Published: February 2014

In recent years, as space structures have become large and require higher accuracy, composite honeycombs, which can reduce weight and have low thermal expansion, are in increasing demand. As observed in the design of antenna reflectors and rocket bodies, both flat and 3D-shaped cores are used in this field. However, these special honeycombs have high manufacturing costs and limited applications. This study illustrates a new strategy to fabricate arbitrary cross-section honeycombs with applications of advanced composite materials. These types of honeycombs are usually manufactured from normal flat honeycombs by curving or carving, but the proposed method enables us to construct objective shaped honeycombs directly. The authors first introduce the concept of the kirigami honeycomb, which is made from single flat sheets and has periodical slits resembling origami. In previous studies, honeycombs having various shapes were made using this method, and were realized by only changing folding line diagrams (FLDs). In this study, these 3D kirigami honeycombs are generalized by numerical parameters and fabricated using a newly proposed FLD design method, which enables us to draw the FLD of arbitrary cross-section honeycombs. Next, the authors describe a method of applying this technique to advanced composite materials. Applying the partially soft composite techniques, folding lines are materialized by silicon rubber hinges on carbon fiber reinforced plastic. Complex FLD patterns are then printed using masks on carbon fabrics. Finally, these foldable composites that are cured in corrugated shapes in autoclaves are folded into honeycomb shapes, and some typical samples are shown with their FLDs.
Marginal Stability in ℒ1-Adaptive Control of Manipulators
Authors: Nguyen Kim-Doang , Dankowicz Harry , Hovakimyan Naira
Published: February 2014

This paper presents a preliminary analysis of the robustness of a recently-proposed adaptive controller for robot manipulators based on the ℒ1 control paradigm. Here, the use of a low-pass filter in the control input decouples the estimation loop from the control loop, thereby facilitating an arbitrary increase of estimation rates (limited only by hardware) without sacrificing robustness. Tuning of the filter also allows for shaping the nominal response and enhancing the system’s robustness. The paper further demonstrates improvements in the critical time delay associated with a static reference input achieved through the introduction of time delay in the state-predictor formulation. Guided by results from the theory of single-input-single-output ℒ1 control systems, a linear, time-invariant system is proposed in order to derive a conservative lower bound on the system’s actuator critical time delay for static reference input in the limit of large estimation gains, as an indicator of robustness. Finally, a numerical method is proposed for quantifying the robustness against time delay of the system’s response to a given static reference input based on techniques of parameter continuation. This method computes the critical time delay at which local stability is lost in a Hopf bifurcation. The dependence of this critical time delay on control parameters, such as adaptive gains and filter bandwidth, is here obtained using advanced algorithms for computing approximate covers of implicitly defined manifolds.
Fractional Order Coulomb Friction Compensation: Convergence Analysis and Experimental Validation on a Fractional Horsepower Dynamometer
Authors: Dadras Sara , Malek Hadi , Chen YangQuan
Published: February 2014

A new fractional order adaptive scheme is proposed for the Coulomb friction compensation in a servo control system. This adaptive compensator is designed such that it can estimate the unknown Coulomb friction coefficient; therefore, the zero convergence of the error system will be guaranteed. The design procedure of the proposed control scheme is very simple and its application is easy. Also, the friction in the servo control system is compensated by a good tracking performance. The comparison shows that the fractional order compensator has less tracking error and better response. A fractional horsepower dynamometer was developed as a general purpose hardware-in-the-loop real-time simulation platform to emulate Coulomb friction as a mechanical nonlinearity. The simulation and experimental results demonstrate that the proposed controller has a satisfactory performance and diminishes friction characteristics.
Origami Rotors: Imparting Continuous Rotation to a Moving Platform Using Compliant Flexure Hinges
Authors: Moses Matthew S. , Ackerman M. Kendal , Chirikjian Gregory S.
Published: February 2014

A mechanism that admits continuous free rotation between a fixed platform and a rotating body is described. The mechanism is a serial kinematic chain with several revolute joints. The end of the kinematic chain has free and unlimited rotational motion, equivalent to a standard mechanical pivot, but the travel of each individual joint in the chain is limited to less than ±70 degrees. The joints that compose the chain can thus be constructed using compliant flexure hinges. The entire mechanism can be folded from a single flat sheet of material, and is thus well suited for self-assembly by folding, which is an increasingly attractive technique for building micro-scale devices. Potential applications include rotating propellers for micro underwater or fluid-immersed (e.g. within a blood vessel) robots, and high-mobility wheel-legs for crawling vehicles.
A Smooth Wave-Form Command Shaping Control
Authors: Alhazza Khaled A. , Masoud Ziyad N. , Alotaibi Nehal
Published: February 2014

To avoid excitation of higher modes of flexible and multi-mode systems, it is important to eliminate sudden and jerky inputs. To achieve this goal, researchers tend to use different smoothing techniques to reduce the effect of the command roughness. In this work, a new smooth command-shaping technique for oscillation reduction of simple harmonic oscillators is proposed. A continuous smooth wave-form acceleration command-shaper is proposed. The shaper parameters are tuned to eliminate residual vibrations in rest-to-rest maneuvers. The performance of the proposed shaper is determined analytically, simulated numerically, and validated experimentally on a scaled model of an overhead crane. Results obtained show that the proposed smooth wave-form shaper is capable of eliminating travel and residual oscillations. Furthermore, unlike traditional step command shapers, the proposed command profiles have completely smooth acceleration, velocity, and displacement profiles. Experimental results demonstrate the ability of our proposed smooth wave-form commands to eliminate residual vibrations at the end of rest-to-rest maneuvers.
Flexoelectric Energy Harvesting of Circular Rings
Authors: Zhang X. F. , Hu S. D. , Tzou H. S.
Published: February 2014

Flexoelectricity, the electromechanical coupling of the polarization response and strain gradient, occurs in solid crystalline dielectrics of any symmetry or asymmetric crystals. Different from the piezoelectric energy harvester, an energy harvester based on the direct flexoelectric effect is designed in this study. The energy harvester consists of an elastic ring and a flexoelectric patch laminated on its outer surface. Due to the direct flexoelectric effect, the electric energy induced by the strain gradient of the flexoelectric patch is harvested to power the electric device when the ring is subjected to mechanical excitations. Electromechanical coupling equation of the flexoelectric energy harvesting system in close-loop circuit condition is derived. In this study, dynamic response, output power across the external resistor and energy harvesting results are evaluated when the ring is excited by a harmonic point loading. The output power is a function of the external excitation frequency, the external equivalent resistance, the flexoelectric patch’s thickness and other design parameters. Case studies of those parameters for the flexoelectric energy harvester are presented to optimize the output power. Results show that the optimal excitation frequency is equal to the natural frequency for each mode, and the optimal equivalent resistance is dependent of the equivalent capacitance of the flexoelectric patch and the excitation frequency. Since the output power of the flexoelectric energy harvester is similar to that of the piezoelectric energy harvester, comparison of the two harvesters is also discussed. With all the optimal conditions discussed, it can supply a design principle in the engineering applications.
High Efficiency Electromagnetic Energy Harvester for Railroad Application
Authors: Wang John , Lin Teng , Zuo Lei
Published: February 2014

A mechanical motion rectifier (MMR) based energy harvester is designed to harness the vibrational power from railroad track deflections due to passing trains. Whereas typical existing vibration energy harvester technologies are built for low power applications of milliwatts range, the proposed harvester will be designed for higher power applications such as major track-side equipment. This includes warning signals, switches, and health monitoring systems, which typically require a power supply of 10–100 Watts. To achieve this goal we implement the MMR, a newly patented motion conversion mechanism which efficiently transforms irregular pulse-like bidirectional linear vibration into regulated unidirectional rotational motion. The single-shaft MMR design improves previously developed motion conversion technologies, increasing energy harvester efficiency and power harvesting potential. Features of the MMR include bidirectional to unidirectional motion conversion and flywheel speed regulation. Its advantages include improved reliability, efficiency, and steadier output power. Harvester prototype testing results illustrate features and benefits of the MMR based harvester, showing reduction of continual system loading, regulation of generator speed, and capability for continuous DC power generation.
Ground-Based Response of a Spinning, Cyclic Symmetric Rotor Assembled to a Flexible Stationary Housing via Multiple Bearings
Authors: Tai W. C. , Shen I. Y.
Published: February 2014

This paper is to study free response of a spinning, cyclic symmetric rotor assembled to a flexible housing via multiple bearings. In particular, the rotor spins at a constant speed ω3, and the housing is excited via a set of initial displacements. The focus is to study ground-based response of the rotor through theoretical and numerical analyses. The paper consists of three parts. The first part is to briefly summarize an equation of motion of the coupled rotor-bearing-housing systems for the subsequent analyses. The equation of motion, obtained from prior research [1], employs a ground-based and a rotor-based coordinate system to the housing and the rotor, respectively. As a result, the equation of motion takes the form of a set of ordinary differential equations with periodic coefficients of frequency ω3. To better understand its solutions, a numerical model is introduced as an example. In this example, the rotor is a disk with four radial slots and the housing is a square plate with a central shaft. The rotor and housing are connected via two ball bearings. The second part of the paper is to analyze the rotor’s response in the rotor-based coordinate system theoretically. When the rotor is at rest, let ωH be the natural frequency of a coupled rotor-bearing-housing mode whose response is dominated by the housing. The theoretical analysis then indicates that response of the spinning rotor will possess frequency components ωH ± ω3 demonstrating the interaction of the spinning rotor and the housing. The theoretical analysis further shows that this splitting phenomenon results from the periodic coefficients in the equation of motion. The numerical example also confirms this splitting phenomenon. The last part of the paper is to analyze the rotor’s response in the ground-based coordinate system. A coordinate transformation shows that the ground-based response of the spinning rotor consists of two major frequency branches ωH − (k + 1) ω3 and ωH − (k − 1) ω3, where k is an integer determined by the cyclic symmetry and vibration modes of interest. The numerical example also confirms this derivation.
Study the Impact of Driver’s Behavior on the Energy Efficiency of Hybrid Electric Vehicles
Authors: Feng Lei , Chen Bo
Published: February 2014

This paper investigates the impact of driver’s behavior on the fuel efficiency of a hybrid electric vehicle (HEV) and its powertrain components, including engine, motor, and battery. The simulation study focuses on the investigation of power request, power output, energy loss, and operating region of powertrain components with the change of driver’s behavior. It is well known that a noticeable difference between the sticker number fuel economy and actual fuel economy will happen when a driver drives aggressively. To simulate aggressive driving, the input driving cycles are scaled from the baseline driving cycles to increase the level of acceleration/deceleration. With scaled aggressive driving cycles, the simulation result shows a significant change of HEV equivalent fuel economy. In addition, the high power demands of aggressive driving cause engine to operate within a higher fuel rate region. Furthermore, the engine is started and shut down frequently due to the large instantaneous power request peaks, which result in high energy loss. The simulation study of the impact of aggressive driving on the HEV fuel efficiency is conducted for a power-split hybrid electric vehicle using powertrain simulation and analysis software Autonomie developed by Argonne National Laboratory. The performance of the major powertrain components is analyzed when the HEV operates at different level of aggressiveness. The simulation results provide useful information to identify the major factors that need to be included in the vehicle control design to improve the fuel efficiency of HEVs under aggressive driving.
Validating the Coupling of Multibody Dynamic Simulations With Sea Keeping Simulations
Authors: Hannot Stephan D. A. , Los Jan G. , van Spaendonk Bram A. W. , Kruijswijk Alex B. , de Krijger Albert C. L.
Published: February 2014

Dredging is the activity of excavating soil or other sediments from the bottom of a water body such as a lake or sea. The purpose of dredging varies: e.g. maintaining the depth of waterways or obtaining material for beach nourishment. Most ‘dredgers’ are composed of a floating structure (ship or pontoon) on which the dredging equipment that is used to excavate at the seabed is installed.

Dredging at open sea, offshore dredging, becomes a more common operating condition. This means that dredgers will have to be designed with surface wave induced motions and forces in mind. Therefore simulating the motions of dredgers due to surface waves coupled with the motion of the dredging equipment is an important design analysis step. This requires a tool that can simulate a coupled sea keeping and multibody dynamic problem. In this work the theory, development and validation of such a simulation tool are discussed.
Critical Timescales for Burrowing in Undersea Substrates via Localized Fluidization, Demonstrated by RoboClam: A Robot Inspired by Atlantic Razor Clams
Authors: Winter Amos G. , Deits Robin L. H. , Dorsch Daniel S.
Published: February 2014

The Atlantic razor clam (Ensis directus) burrows into underwater soil by using motions of its shell to locally fluidize the surrounding substrate. The energy associated with movement through fluidized soil — characterized by a depth-independent density and viscosity — scales linearly with depth. In contrast, moving through static soil requires energy that scales with depth squared. For E. directus, this translates to a 10X reduction in the energy required to reach observed burrow depths. For engineers, localized fluidization offers a mechanically simple and purely kinematic method to dramatically reduce burrowing energy. This concept is demonstrated with RoboClam, an E. directus-inspired robot. Using a genetic algorithm to generate digging kinematics, RoboClam has achieved localized fluidization and burrowing performance comparable to that of the animal, with a linear energy-depth relationship. In this paper, we present the critical timescales and associated kinematics necessary for achieving localized fluidization, which are calculated from soil parameters and validated via RoboClam and E. directus testing.
On the History of Lateral Dynamics Modelling for Rail and Road Vehicles
Authors: Schiehlen Werner
Published: February 2014

The lateral motion of ground vehicles is characterized by the rolling contact between wheels and guideway. Railway vehicles feature passive lateral guidance while road vehicles are operated by steering. Lateral dynamics is an extremely complex problem but the fundamental behaviour can already understood by strongly simplified mechanical models. In this paper the historical development of modelling approaches for lateral dynamics is reviewed what is very helpful for checking more complex problems, too.