bluuebunny/crossref_metadata_2025 huggingface dataset:
Störmer-Verlet Integration Scheme for Multibody System Dynamics in Lie-Group Setting
Authors: Terze Zdravko , Mueller Andreas , Zlatar Dario
Published: February 2014

Störmer-Verlet integration scheme has many attractive properties when dealing with ODE systems in linear spaces: it is explicit, 2nd order, linear/angular momentum preserving and it is symplectic for Hamiltonian systems. In this paper we investigate its application for numerical simulation of the multibody system dynamics (MBS) by formulating Störmer-Verlet algorithm for the rotational rigid body motion in Lie-group setting. Starting from the investigations on the single free rigid body rotational dynamics, the paper introduces modified RATTLE integration scheme with the direct SO(3) rotational update. Furthermore, non-canonical Lie-group Störmer-Verlet integration scheme is presented through the different derivation stages. Several presented numerical examples show excellent conservation properties of the proposed geometric algorithm.
Energy Harvesting for Smart Shoes: A Real Life Application
Authors: Frontoni Emanuele , Mancini Adriano , Zingaretti Primo , Gatto Andrea
Published: February 2014

Advanced technical developments have increased the efficiency of devices in capturing trace amounts of energy from the environment (such as from human movements) and transforming them into electrical energy (e.g., to instantly charge mobile devices). In addition, advancements in microprocessor technology have increased power efficiency, effectively reducing power consumption requirements.

In combination, these developments have sparked interest in the engineering community to develop more and more applications that utilize energy harvesting for power. The approach here described aims to designing and manufacturing an innovative easy-to-use and general-purpose device for energy harvesting in general purpose shoes. The novelty of this device is the integration of polymer and ceramic piezomaterials accomplished by injection molding. In this spirit, this paper examines different devices that can be built into a shoe, (where excess energy is readily harvested) and used for generating electrical power while walking. A Main purpose is the development of an indoor localization system embedded in shoes that periodically broadcasts a digital RFID as the bearer walks. Results are encouraging and real life test are conducted on the first series of prototypes.
Virtual Test Environment for Self-Optimizing Systems
Authors: Stöcklein Jörg , Baldin Daniel , Müller Wolfgang , Xie Tao
Published: February 2014

In our paper we present a virtual test environment for self-optimizing systems based on mutant based testing to validate user tasks of a real-time operating system. This allows the efficient validation of the code coverage of the test cases and therefore helps to detect errors in order to improving the reliability of the system software.

Technically we are able to run and test the software on both systems. By writing application software and setting up the virtual test environment properly, we define our test cases. To validate the code coverage for our test cases, we use the approach of mutant based testing. By running this mutated code on our virtual prototype in the virtual test environment, we are able to efficiently validate the code coverage and are able to detect bugs in the application code or detect dead code that is not executed. Finding non-executing code leads to redefinition of our test cases by either changing the test environment or the application code in the case of dead code.

We implemented the virtual test environment on top of the third party low cost VR system Unity 3D, which is frequently used in entertainment and education. We demonstrate our concepts by the example of our BeBot robot vehicles. The implementation is based on our self-optimizing real-time operating system ORCOS and we used the tool CERTITUDE(TM) for generating the mutations in our application code. Our BeBot virtual prototype in our virtual test environment implements the same low-level interface to the underlying hardware as the real BeBot. This allows a redirection of commands in ORCOS to either the real or the virtual BeBot in order to provide a VR based platform for early software development as well as ensures comparable conditions under both environments.

Our example applies a virtual BeBot that drives through a labyrinth utilizing its IR sensors for navigation. The mutant based testing checks if all situations implemented by the software to navigate through the labyrinth are covered by our tests.
Numerical Flight Vehicle Forward Dynamics With State-Space Lie-Group Integration Scheme
Authors: Terze Zdravko , Vrdoljak Milan , Zlatar Dario
Published: February 2014

Dynamic simulation procedures of flight vehicle maneuvers need robust and efficient integration methods in order to allow for reliable simulation missions. Derivation of such integration schemes in Lie-group settings is especially efficient since the coordinate-free Lie-group dynamical models operate directly on SO(3) rotational matrices and angular velocities, avoiding local rotation parameters and artificial algebraic constraints as well as kinematical differential equations. In the adopted modeling approach, a state-space of the flight vehicle (modeled as a multi-body system comprising rigid bodies) is modeled as a Lie-group. The numerical algorithm is demonstrated and tested within the framework of the characteristic case study of the aircraft 3D maneuver.
Distributed and Collaborative Product Design Concepts Evaluation by Using Heterogeneous Terminal Devices
Authors: Opiyo Eliab Z.
Published: February 2014

It is common in engineering design practice for designers and engineers to evaluate design concepts to determine if the design solutions meet requirements. The common practice has been to use virtual models on visual display terminals and/or physical models to evaluate design concepts. The emerging heterogeneous terminal devices — including mobile terminal devices with miniature displays such as smartphones and tablet PCs — offer alternative ways of visualizing design concepts and of performing the evaluation tasks. In the work presented in this paper, we attempted to address the challenge of using handheld terminal devices with limited computational resources and miniature displays in design concepts evaluation. We propose a new distributed and collaborative product design concepts evaluation scheme in which the evaluation is performed based on virtual models and product data displayed on heterogeneous terminal devices, including handheld devices. This scheme consists of methods and mechanisms that help to sync the needs of the evaluation task at hand with the available computational resources and display specifications. A practical example is used to demonstrate the applicability of the proposed product design concept evaluation scheme and how it can be used in practice. The major contribution of the reported work was creation of novel high-level model pre-processing algorithmic procedures for adapting product models to meet the evaluation task requirements and terminal device resource constraints.
Analysis of Rotor Load Harmonic Composition and Load Transference Between Frames
Authors: McColl Chance C. , Ruzzene Massimo
Published: February 2014

Loads prediction for helicopters is more complex than that for fixed wing aircraft given that the aerodynamic forces that produce the air vehicle’s lift and moments are generated by rotating components (e.g., the main and tail rotors). This paper examines rotor load content as a function of harmonics of the rotor angular speed. Accurate rotor loads prediction is driven by a clear understanding of the underlying physics of the problem. This understanding is important for several reasons. First, additive effects of multiple load components fed from the rotating frame to the fixed frame influence the vibratory response of the hub and fuselage. Second, structural fatigue life is driven by load magnitude as well as the number of applications of each load. The mechanics of load transference between the rotating and fixed frames will also be examined. Examples for 4-bladed and 7-bladed rotors will be presented. Definitions of cyclic/whirl (moment transference), collective (force transference), and reactionless/warp (zero force, zero moment transference) modes will be presented for a generic n-bladed rotor. US Army UH-60A Black Hawk flight test data will be examined. Blade lift, main rotor shaft bending, pushrod axial load, and fixed system servo loads will be derived and compared with measured UH-60A results. The intent of this paper is to provide clear insight into the nature of rotor load harmonic composition and load transference between the fixed and rotating frames for a rotor — two areas not well documented (and never visually described) in the literature.
Euler-Lagrange Equations on Cantor Sets
Authors: Baleanu Dumitru , Yang Xiao-Jun
Published: February 2014

In this manuscript, we investigated the Euler-Lagrange equations on Cantor sets within the local fractional operators. To illustrate the proposed method two examples are presented.
Noise-Influenced Dynamics of a Vertically Excited Pendulum
Authors: Perkins Edmon , Balachandran Balakumar
Published: February 2014

While the effects of noise on a dynamical system are often considered to be detrimental, noise can also have beneficial effects on the response of a system. In this work, the vertically excited pendulum is used as an example to illustrate the beneficial effects of noise. The upright equilibrium position of this system can be stabilized passively with a high-frequency excitation by utilizing the system nonlinearities and a bifurcation. After introducing white Gaussian noise into the pendulum pivot motion, the stability of the system prior to this bifurcation is analyzed. It is shown that white Gaussian noise has the potential to stabilize the unstable equilibrium point. Considering the bi-stable pendulum, a control scheme is introduced which utilizes only noise to switch between the two stable equilibrium points. This system is studied on the basis of an Itō scheme and direct numerical simulations are carried out by using the Euler-Maruyama method, and also with a semi-analytical formulation based on the Fokker-Planck equation. The results of the work can provide a basis to develop noise-utilizing controllers.
Multi-Objective Robust Optimization Design of a Fixed-Speed Horizontal Axis Wind Turbine
Authors: Wang Weijun , Caro Stéphane , Bennis Fouad
Published: February 2014

The produced power and the thrust force exerted on the wind turbine are two conflicting objectives in the design of a floating horizontal axis wind turbine. Meanwhile, the variations in design variables and design environment parameters are unavoidable. The variations include the small variations in the design variables due to manufacturing errors, and the large variations in the wind speed. Therefore, two robustness indices are introduced in this paper. The first one characterizes the robustness of multi-objective optimization problems against small variations in the design variables and the design environment parameters. The second robustness index characterizes the robustness of multi-objective optimization problems against large variations in the design environment parameters. The robustness of the solutions based on the two robustness indices is treated as a vector defined in the robustness function space. As a result, the designer can compare the robustness of all Pareto optimal solutions and make a decision. Finally, the multi-objective robust optimization design of a fixed-speed horizontal axis wind turbine illustrates the proposed methodology.
The Boundary Smoothing in Discrete Topology Optimization of Structures
Authors: Zhou Hong , Mohammed Shabaz Ahmed
Published: February 2014

In discrete topology optimization, material state is either solid or void and there is no topology uncertainty caused by intermediate material state. A common problem of the current discrete topology optimization is that boundaries are unsmooth. Unsmooth boundaries are caused by corners in topology solutions. Although the outer corner cutting and inner corner filling strategy can mitigate corners, it cannot eliminate them. 90-degree corners are usually mitigated to 135-degree corners under the corner handling strategy. The existence of corners in topology solutions is because of the subdivision model. If regular triangles are used to subdivide design domains, corners are inevitable in topology solutions. To eradicate corner from any topology solution, a subdivision model is introduced in this paper for the discrete topology optimization of structures. The design domain is discretized into quadrilateral design cells and every quadrilateral design cell is further subdivided into triangular analysis cells that have a curved hypotenuse. With the presented subdivision model, all boundaries and connections are smooth in any topology solution. The proposed subdivision approach is demonstrated by two discrete topology optimization examples of structures.
On a Consistent Application of Newton’s Law to Constrained Mechanical Systems
Authors: Paraskevopoulos Elias , Natsiavas Sotirios
Published: February 2014

An investigation is carried out for deriving conditions on the correct application of Newton’s law of motion to mechanical systems subjected to constraints. It utilizes some fundamental concepts of differential geometry and treats both holonomic and anholonomic constraints. The focus is on establishment of conditions, so that the form of Newton’s law remains invariant when imposing an additional set of motion constraints on a system. Based on this requirement, two conditions are derived, specifying the metric and the form of the connection on the new manifold. The latter is weaker than a similar condition employed frequently in the literature, but holding on Riemannian manifolds only. This is shown to have several practical implications. First, it provides a valuable freedom for selecting the connection on the manifold describing large rigid body rotation, so that the group properties of this manifold are preserved. Moreover, it is used to state clearly the conditions for expressing Newton’s law on the tangent space (and not on the dual space) of a manifold. Finally, the Euler-Lagrange operator is examined and issues related to equations of motion for anholonomic and vakonomic systems are investigated.
On the Design of a Portable Force Illusion Device for Navigation Aids
Authors: Wever Jacobus W. M. , Gosselin Clement , Herder Just L.
Published: February 2014

Navigation aids rely mostly on (audio)visual cues when it comes to communication with the user. An alternative and more intuitive communication modality may be provided by means of haptic guidance generated by a portable mechatronic device. Especially visually impaired and blind people may benefit from a device that generates the illusion of an external force; it may possibly eliminate the need for a guide dog. This paper investigates constant-velocity crank-driven mechanisms which are able to generate such a force illusion by means of a reciprocating mass. The focus of this paper is on the generation of the illusion itself rather than manipulating the direction of this force. The force illusion is a result of successive positive and negative reaction forces with unequal amplitude, generated by a reciprocating mass. The acceleration ratio of the mass is selected as the main evaluation criterion for comparing different types of candidate mechanisms. Because the input is a simple motor rotating at a constant velocity, the synthesis of the mechanism is key to generating proper acceleration profiles. A brute-force approach is used for the synthesis procedure, i.e., characteristic distances and link lengths are varied with steps of 1mm for each of the candidate mechanisms, thereby generating very large numbers of variants. Kinematic performance reveal typical acceleration ratios in the range of 1 to 19; where a ratio of one does not result in a force illusion while a ratio of 19 might be demanding on the physical design. An objective evaluation leads to selecting the Square Recti-Linear mechanism as the overall most promising candidate mechanism. A prototype of this mechanism is then presented to demonstrate the working principle. The shape of the prototype’s force profile over time is measured experimentally and is shown to be very similar to the profile obtained by simulation. The reciprocating mass accounts for almost one fifth of the total mass of the prototype, resulting in a strong force illusion in comparison with gravitational forces.
Large Angle of Attack Wheel Climb
Authors: Shabana Ahmed A. , O’Shea James J.
Published: February 2014

It is shown in this paper that wheel climb can be initiated as the result of kinematic conditions that can be described using algebraic equations that do not depend explicitly on time. These algebraic kinematic conditions can lead to instantaneous wheel climb that is independent of the motion history. The analysis presented in this paper shows that if the contact is maintained at the wheel perimeter, a single kinematic constraint equation, expressed in terms of the wheel generalized coordinates, is obtained. This algebraic constraint equation clearly shows that a decrease in the lateral distance between the center of mass of the wheel and the rail, which can be the result of application of a lateral force, leads to an instantaneous wheel climb in the case of a constant angle of attack. It is shown that the ratio between the lateral and vertical reaction forces at the contact point is governed by a well-defined algebraic equation, and such a ratio does not depend on the applied forces. This ratio is given by dy/(dz sin2 α), where dy and dz are, respectively, the lateral and vertical distances of the wheel center from the contact point, and α is the angle of attack. In order to develop the governing dynamic equations, the kinematic constraint equations are used to derive a velocity transformation matrix that defines the relationship between the wheel velocities and the derivatives of the degrees of freedom. This velocity transformation matrix is used to obtain the independent wheel equations of motion which are solved numerically to determine the wheel motion in response to different lateral and friction forces. The results obtained show that wheel climb can be initiated with small lateral force, and an increase in the lateral force is not necessary for climb initiation. In order to shed light on the L/V ratio commonly used in wheel climb derailment criteria, the relationship between the external lateral force acting on the wheel and the reaction lateral force at the contact point is developed in this investigation. It is also shown that in the case of a tangent track and zero roll angle; the wheel longitudinal motion is completely decoupled from the vertical and yaw displacements. Therefore, the use of the distance to climb in tangent track wheel climb criteria needs to be reexamined.
Peer Learning Using Smart Devices: A Report on Work-in-Progress
Authors: Okudan Kremer Gül E. , Akashesh Firas , Siddique Zahed , Abou-Nassar Guy
Published: February 2014

Our approach is to capitalize on the research findings on linkages between higher-order thinking and peer learning to create and evaluate a learning environment, entitled Teaching to Learn (TeatoL). TeatoL blends mobile smart devices and traditional approaches to enhance critical thinking and competencies essential for students to solve open-ended problems. The main objective is to understand, develop, implement and evaluate a peer-learning environment utilizing mobile technologies and devices. The focus is on peer learning mode, where students are instructors to share their experience and then learn from fellow student instructors.

In this paper, we present our vision of this learning medium along with the foundation we have built it upon. Within TeatoL students are introduced to a “flatter” instructional environment; all participants have dual roles as students and instructors who are embedded in a collaborative environment where all learn collectively from each other’s experiences, even the instructor. We also discuss hypothesized benefits and our on-going work on initial implementation and its assessment. We close the paper with observations from our initial implementations across three data collection sites.
Multiscale Topology Optimization of Structures and Periodic Cellular Materials
Authors: Liu Kai , Tovar Andrés
Published: February 2014

The introduction of cellular materials models in topology optimization allows designers to achieving significant weight reductions in structural applications. However, higher material savings and increased performance can be achieved if the material and the structure topologies are concurrently designed. The objective of this paper is to incorporate and establish a design methodology to obtaining optimal macro-scale structures and the corresponding optimal meso-scale periodic material designs in continuum design domains. The proposed approach makes use of homogenization theory to establish communication bridges between both material and structural scales. The periodicity constraint makes such cellular materials manufacturable. Penalization methods are used to obtaining binary solutions in both scales. This proposed methodology is demonstrated in the design of compliant mechanisms and structures of minimum compliance. The results demonstrate potential benefits when this multi-scale design algorithm when applied to the design of ultra-lightweight structures.
Integration of Education and Research in Mechatronics Engineering Programs
Authors: Vantsevich Vladimir V.
Published: February 2014

Based on extensive experience of establishing and teaching new mechatronic systems engineering courses and M.Sc.-degree program since 2006 at Lawrence Technological University, this paper concentrates on the integration of education and engineering research processes.

The paper analyzes challenges such as the content of each academic course and cross-lists all the courses to provide the continuity of education/research process in the mechatronic systems engineering program, selection of modeling and design techniques, usage of software products in the courses and research projects, different educational degrees (including students with PhD degrees) and professional backgrounds of mechatronics students, domestic/international student ratio, and part time/full time student ratio.

Based on the analysis of the challenges, a key plan for the education-research integration was developed and implemented. Details are in the paper.
Design Ideation Framework to Support Reframing and Reformulation
Authors: Narsale Sumit Sunil , Chen Ying , Khorshidi Maryam , Shah Jami J.
Published: February 2014

The long term aim of this research is to develop a framework for holistic ideation which will integrate both intuitive and experiential methods. Towards that goal, we have developed a computer tool that consists of a variety of disparate knowledge-bases, databases and design repositories that the designer can choose from as his ideation state evolves. Such a strategy is in contrast with the approach of using a single ideation method/tool. Conceptual design requires both problem formulation/re-formulation and alternative generation. This paper discusses an organizational framework to support reformulation and ideation in a multi-tool environment. The proposed framework consists of cascading hierarchical morphological charts that are dynamic. We also discuss how this framework can be used in supporting provocative stimuli, analogical reasoning and make random or deliberate connections between sub-solutions. Web implementation of the tool will make it available to the design community for education and experimentation.
A Black Box Model for Estimating Joint Torque in an Industrial Serial Manipulator
Authors: Schroeder Kyle A. , Pryor Mitch , Harden Troy
Published: February 2014

Joint torque feedback is useful in serial manipulator control algorithms for contact control, collision detection, performance analysis, etc. For example, the predicted torque can be compared to the measured torque so the system can respond to unexpected or unmodeled physical inputs. The input current to the joint motors can be used to estimate the input torque if the motor parameters are well-understood. However, in a closed commercial system, the motor parameters are often proprietary or unknown. Also, systems that sense or estimate motor torques instead of the joint torques require compensation for gear train losses.

In this work, we propose a method for mapping the measured motor current to the joint torque on a serial manipulator without joint torque sensors, thus advancing the potential to implement torque feedback algorithms such as collision detection on any industrial robot with joint position and motor current feedback. This new torque estimating technique (as opposed to using Newton-Euler dynamics) allows for sensing of external forces in collision detection applications for a position controlled robot.

The method requires knowledge of the robot link centers of mass, masses, and inertias and that the motor currents and joint positions can be measured. The joint torques due to gravity, inertia, and Coriolis are estimated by the Newton-Euler method using the system geometry, link masses, and the measured joint positions. A method for estimating friction losses using only the current and the predicted joint torque is demonstrated. The measured current, less estimated friction, is then mapped to the joint torque.

The validity of the black box joint torque estimating model was demonstrated using two Motoman SIA-5D manipulators with a 3rd party controller provided by Agile Planet. The joints of the robot were moved through a variety of test motions with known joint torque characteristics (as calculated using Newton-Euler dynamics). Estimated joint torques are similar to the calculated torque. Physical significance of the torque is validated by comparing the estimated torque to the calculated torque generated by a known force. The feasibility of the estimated torque error to force detection is discussed in terms of improving the safety and deployment options for industrial robotic systems.
Advanced Beam Theory for Multibody Dynamics
Authors: Bauchau Olivier A. , Han Shilei
Published: February 2014

In flexible multibody systems, many components are often approximated as beams or shells. More often that not, classical beam theories, such as Euler-Bernoulli beam theory, form the basis of the analytical development for beam dynamics. The advantage of this approach is that it leads to a very simple kinematic representation of the problem: the beam’s section is assumed to remain plane and its displacement field is fully defined by three displacement and three rotation components. While such approach is capable of capturing the kinetic energy of the system accurately, it cannot represent the strain energy adequately. For instance, it is well known from Saint-Venant’s theory for torsion that the cross-section will warp under torque, leading to a three-dimensional deformation state that generates a complex stress state. To overcome this problem, sectional stiffnesses are computed based on sophisticated mechanics of material theories that evaluate the complete state of deformation. These sectional stiffnesses are then used within the framework of an Euler-Bernoulli beam theory based on far simpler kinematic assumptions. While this approach works well for simple cross-sections made of homogeneous material, very inaccurate predictions result for realistic sections, specially for thin-walled beams, or beams made of anisotropic materials. This paper presents a different approach to the problem. Based on a finite element discretization of the cross-section, an exact solution of the theory of three-dimensional elasticity is developed. The only approximation is that inherent to the finite element discretization. The proposed approach is based on the Hamiltonian formalism and leads to an expansion of the solution in terms of extremity and central solutions, as expected from Saint-Venant’s principle.
Study of the Stick-Slip Transition of Newton’s Cradle With Friction
Authors: Rodriguez Adrian , Bowling Alan
Published: February 2014

This work uses a new discrete approach to analyze the stick-slip transition of Newton’s cradle with frictional contact. The consideration of friction here leads to a simultaneous, multiple point, indeterminate collision. This work strictly adheres to the assumptions of rigid body modeling in conjunction with the notion that the configuration of the system are constant in the short time span of the collision, which enforces a kinematic relationship between the impact points. The post-impact velocities are determined by using the work-energy relationship of a collision and an energetic coefficient of restitution (ECOR) to model energy dissipation. A three and six degree-of-freedom (DOF) model of the system is considered in this work to examine the stick-slip transition and simulate the post-impact behavior. Simulations are conducted for each model using different coefficients of friction (COFs). The results obtained are compared to theoretical and experimental results reported in other works.
Predicting Consumer Choice Set Using Product Association Network and Data Analytics
Authors: Wang Mingxian , Chen Wei
Published: February 2014

Although discrete choice analysis has been shown to be useful for modeling consumer preferences and choice behaviors in the field of engineering design, information of choice set composition is often not available in majority of the collected consumer purchase data. When a large set of choice alternatives exist for a product, such as automotive vehicles, randomly choosing a small set of product alternatives to form a choice set for each individual consumer will result in misleading choice modeling results. In this work, we propose a data-analytics approach to mine existing data of choice sets and predict the choice set for each individual customer in a new choice modeling scenario where the choice set information is lacking. The proposed data-analytics approach integrates product association analysis, network analysis, consumer segmentation, and predictive analytics. Using the J.D. Power vehicle survey as the existing choice set data, we demonstrate that the association network approach is capable of recognizing and expressively summarizing meaningful product relations in choice sets. Our method accounts for consumer heterogeneity using the stochastic generation algorithm where the probability of selecting an alternative into a choice set integrates the information of customer profile clusters and products chosen frequencies. By comparing multiple multinomial logit models using different choice set compositions, we show that the choice model estimates are sensitive to the choice set compositions and our proposed method leads to improved modeling results. Our method also provides insights into market segmentation that can guide engineering design decisions.
Nonlinear Flexural Vibrations of Unshearable Elastic Rings
Authors: Lacarbonara Walter , Arena Andrea , Antman Stuart S.
Published: February 2014

Refined theories are employed to study nonlinear vibrations of elastic rings in the mth flexural mode away from autoparametric resonances involving other flexural modes. A top-down modeling approach is followed to describe the rings undergoing all deformation modes in space by the Special Cosserat theory of curved rods. The specialization to extensional-flexural-shearing, then to extensional-flexural, and finally to purely flexural planar motions is illustrated. Free undamped extensional-flexural nonlinear motions involving the mth mode and its companion mode are investigated via a direct asymptotic approach based on the method of multiple scales applied to the geometrically exact equations of motion and it is shown that these motions are softening for linearly elastic rings while there are thresholds in the constitutive laws separating softening from hardening behaviors.
Lightweight Design of a Brake Caliper
Authors: Ballo Federico Maria , Gobbi Massimiliano , Mastinu Giampiero , Pishdad Amir
Published: February 2014

As lightweight design assumes greater importance in road vehicles development, the present paper is mainly devoted to the structural optimization of a brake caliper.

In the first part of the study a simplified finite element model based on beam elements of a brake caliper has been developed and validated.

By using the developed model, a multi-objective optimization has been completed. The total mass of the caliper and the deformations at some critical locations have been minimised. The considered design variables are related to the shape of the caliper and the cross sections of the beam elements.

The obtained optimal solutions are characterized by an asymmetric shape of the caliper. Optimised symmetric shapes currently used have been compared with the asymmetric ones in terms of performance.

In the second part of the study, a detailed analysis on the optimal caliper shape has been carried out by performing a structural topology optimization.

The minimum compliance problem has been solved using the SIMP (solid isotropic material with penalization) approach and the optimal solution has been compared with the ones obtained by applying the multi-objective optimization on the simplified model (beam elements).

The obtained design solutions represent a good starting point for future developments in actual industrial applications.
An Assessed Model for the Vibro-Acoustic Analysis of Gear Pumps
Authors: Mucchi Emiliano , Dalpiaz Giorgio
Published: February 2014

In this work a combined model for the vibro-acoustic analysis of an external gear pump for automotive applications is presented and experimentally assessed. The model includes a lumped-parameter model, a finite-element model and a boundary-element model. The lumped-parameter (LP) model regards the interior parts of the pump (bearing blocks and gears), the finite element (FE) model regards the external parts of the pump (casing and end plates), while the boundary element (BE) model estimates the noise generation in operational conditions. Attention has been devoted to the inclusion of the oil effect inside the pump casing: the fluid-structure interaction between oil and pump casing was taken into account. The model has been assessed using experiments: the experimental accelerations and acoustic pressure measured in operational conditions have been compared with the simulated data coming from the combined LP/FE/BE model. Eventually, model results and limitations are presented.
Optimal Tuning of Centrifugal Pendulum Vibration Absorbers
Authors: Shi Chengzhi , Parker Robert G. , Shaw Steven W.
Published: February 2014

This note provides an analytical proof of the optimal tuning of centrifugal pendulum vibration absorbers (CPVAs) to reduce in-plane translational and rotational vibration for a rotor with N cyclically symmetric substructures attached to it. The reaction forces that the substructures (helicopter or wind turbine blades, for example) exert on the rotor are first analyzed. The linearized equations of motion for the vibration are then solved by a gyroscopic system modal analysis procedure. The solutions show that the rotor translational vibration at order j is reduced when one group of CPVAs is tuned to order jN − 1 and the other is tuned to order jN + 1. Derivation of this result is not available in the literature. The current derivation also yields the better known result that tuning CPVAs to order jN reduces rotational rotor vibration at order j.
Preposterior Analysis to Select Experimental Responses for Improving Identifiability in Model Uncertainty Quantification
Authors: Jiang Zhen , Chen Wei , Apley Daniel W.
Published: February 2014

In physics-based engineering modeling and uncertainty quantification, distinguishing the effects of two main sources of uncertainty — calibration parameter uncertainty and model discrepancy — is challenging. Previous research has shown that identifiability can sometimes be improved by experimentally measuring multiple responses of the system that share a mutual dependence on a common set of calibration parameters. In this paper, we address the issue of how to select the most appropriate subset of responses to measure experimentally, to best enhance identifiability. We propose a preposterior analysis approach that, prior to conducting the physical experiments but after conducting computer simulations, can predict the degree of identifiability that will result using different subsets of responses to measure experimentally. We quantify identifiability via the posterior covariance of the calibration parameters, and predict it via the preposterior covariance from a modular Bayesian Monte Carlo analysis of a multi-response Gaussian process model. The proposed method is applied to a simply supported beam example to select two out of six responses to best improve identifiability. The estimated preposterior covariance is compared to the actual posterior covariance to demonstrate the effectiveness of the method.
Approach for Stability Analysis of a Cracked Rotor With Time-Varying Stiffness
Authors: Al-Shudeifat Mohammad A.
Published: February 2014

An approach for dynamic stability analysis of a cracked rotor system with transverse crack is addressed here. The time-varying area moments of inertia of the cracked section are employed in formulating the time-periodic finite element stiffness matrix which yields a linear time-periodic system. The harmonic balance method (HB) is used in solving the finite element (FE) equations of motion for studying the dynamic stability of the system. The sign of the determinant of the scaled coefficient matrix resulting from applying the HB solution to the cracked rotor system is found to be a reliable approach for identifying the major unstable regions of the system in the parameter plane obtained by plotting the shaft speeds of rotation vs. the crack depths. Specifically, the negative values of the determinant of this scaled coefficient matrix identify the unstable regions of the cracked system. This approach is applied here to the parametrically excited Mathieu’s equation, two degree-of-freedom gyroscopic system, and then to the FE model of the cracked rotor system. The results of applying this approach are verified using the Floquet’s theory. Compared with the theory, the sign of the determinant of the scaled coefficient matrix is found here to be an efficient tool for identifying the unstable regions of linear parametrically excited systems, especially the large scale dynamic systems where this approach requires considerably less computational time than the Floquet’s theory.
Sensitivity Analysis in Quantified Interval Constraint Satisfaction Problems
Authors: Hu Jie , Wang Yan
Published: February 2014

Interval is an alternative to probability distribution in quantifying epistemic uncertainty for reliability analysis when there is a lack of data to fit a distribution with good confidence. It only requires the information of lower and upper bounds. The propagation of uncertainty is analyzed by solving interval-valued constraint satisfaction problems (CSPs). By introducing logic quantifiers, quantified constraint satisfaction problems (QCSPs) can capture more semantics and engineering intent than CSPs. Sensitivity analysis (SA) takes into account of variations associated with the structure and parameters of interval constraints to study to which extent they affect the output. In this paper, a global SA method is developed for QCSPs, where the effects of quantifiers and interval ranges on the constraints are analyzed based on several proposed metrics, which indicate the levels of indeterminacy for inputs and outputs as well as unsatisfiability of constraints. Two vehicle design problems are used to demonstrate the proposed approach.
New Design of Magnetic Nonlinear Energy Sink for Shock Mitigation in Dynamic Structures
Authors: Al-Shudeifat Mohammad A.
Published: February 2014

Targeted energy transfer is of significant concern in the nonlinear energy sinks (NESs) used for shock (blasts, earthquakes) mitigation in small and large scale dynamic structures which saves human and equipment. The NES is a light-weighted device (<10% of the whole structure mass) which passively absorbs and rapidly dissipates a considerable portion of the initial shock energy induced to the linear dynamic structure. The proposed new design is based on utilizing the permanent magnets that generate a nonlinear repulsive magnetic force which is nearly equivalent to the required stiffness-based NES force. Using magnets instead of stiffness-based elastic materials yields a flexible and compact design of comparable efficiency with the stiffness-based existing NESs. This proposed design is expected to have wide range of applications for either small systems (Aircraft wings) or large scale dynamic structures (large scale buildings or towers). Hence, symmetric and asymmetric designs of magnet-based NESs are considered here to achieve the aimed optimum performance for shock mitigation. The results of the numerical simulation of the symmetric magnet-based NES are found to be comparable to the stiffness-based NES. However the asymmetric magnet-based design has shown better performance than the stiffness-based NES which is promising for the real life applications.
Data and Metering Infrastructure for Sustainable Consumption and Production
Authors: Salahi Niloofar , Jafari Mohsen A. , Lyons Kevin
Published: February 2014

This paper defines a framework to construct a distributed information and computation engine to calculate the energy, material and information flow of a consumer product over the two dimensions of lifecycle and supply chain. These two dimensions construct a network in which energy content calculation is performed using hierarchical top-down mapping of energy flow. At the network’s atomic level (representing industrial or business processes), energy consuming activities as well as data requirements at process or activity level are defined. The question of data metering infrastructure as a critical and key component of such energy content calculation is also addressed. Overall, the approach is to relate system information and metrics on multiple scales and levels of complexity and to integrate this input within a dynamic information processing and knowledge generating framework. Data sourcing and metering infrastructure proposed here consists of three classes of metering structure: Physical Metering, Virtual Metering, and Simulated Metering. The applicability of proposed tools and approaches are demonstrated through a case study relevant to a conventional consumer product’s supply chain.
Uncertain Information Representation and its Usage in Disassembly Modeling
Authors: Zhu Bicheng , Roy Utpal
Published: February 2014

Industrial recycling and reusing are becoming more and more important due to the environmental and economic pressures. They involve disassembly activities to retrieve all the parts or selected parts of a product after its current end-of-life. An information modeling for the disassembly and the optimal disassembly sequence generation based on the information model becomes critical. Most of the currently available information models emphasize on the use of deterministic information or crisp logic, which means, the information is known a priori, and the logic related to them is either true or false. However, this scenario is not true in the real world. If we consider concepts like operation cost and part value as for example, in real life, the disassembly operation cost will be varying according to the efficiency and experience of the operator. The value of the retrieved part is also not a constant number; it is dependent on the condition of the part retrieved. Along with it, the logic developed on this uncertain information is fuzzy. For example, a part might be good, very good, fairly good, poor, and etc. Words like “very”, “fairly” can’t be represented in the crisp logic which requires either a ‘true’ or a ‘false’ value. So, this paper proposes a modified, fuzzy logic–based ontology to represent and further use the uncertain information in a disassembly process, Case studies have been included to illustrate the concept.
Wing Performance Characterization for Flapping Wing Air Vehicles
Authors: Gerdes John W. , Roberts Luke , Barnett Eli , Kempny Johannes , Perez-Rosado Ariel , Bruck Hugh A. , Gupta Satyandra K.
Published: February 2014

Flapping wing air vehicles offer many useful flight characteristics due to their versatility, as proven by flying animals. Wing design significantly influences the performance. However designing successful wings presents significant challenges. Efficient matching of the drive motors to the flapping wings is necessary to overcome the highly constrained weight budget. Simulating detailed information about the force response due to flapping is challenging due to complex fluid-structural interactions of the wings resulting in non-linear force response to flapping motion. To overcome this challenge, we conducted an experimental study of flapping wings to provide detailed temporal force response data for flapping wings. A prototype was built by synthesizing lightweight manufacturing techniques with the results of the experimental study. Our experimental investigations enabled us to select the flapping angle range and flapping frequency.
Life Cycle Assessment and Eco-Design of a Wireless TV/VCR Remote
Authors: Hu Yang , Ameta Gaurav
Published: February 2014

The focus of this paper is to present life-cycle assessment (LCA) of a TV/VCR remote, including alkaline batteries, and to compare the environmental impacts with a redesigned remote consisting of a solar cell. LCA is a very helpful tool in identifying the most important factors for improving product sustainability. The remote considered in this study can control both television and video cassette recorder. This remote is manufactured in Malaysia and exported to the United States. Its life-cycle system includes raw material, parts, shipment, use phase and waste treatment; its life-cycle impact assessment (LCIA) is performed using SimaPro 7.1 and employing the TRACI method. LCA uncertainty analyzing is performed for both remotes utilizing Monte Carlo simulation in SimaPro 7.1.

LCA result shows use of alkaline battery affects most obviously in environmental impacts. In Eco-design remote model, both energy type and raw materials changed. Environmental impacts reduce in five categories in redesigned remote. This paper: 1) presents a prototype design for product using solar cell; 2) presents a novel method for designers to determine raw materials to improve product sustainability in designing stage; 3) provides suggestions for manufacturers to improve product sustainability through reuse of solar cell or a leasing strategy.
Motion Pattern Planning of a Quadruped Robot Based on Parallel Kinematics
Authors: Yu Jingjun , Zhang Zhongxiang , Pei Xu
Published: February 2014

In this paper, kinematic analysis and motion planning of a quadruped robot are presented by regarding the robot as an equivalent parallel platform-type mechanism with RRRS limb structure. Based on screw theory, the mobility of the quadruped robot with different touchdown legs is analyzed, and proves that the design for degree of freedom (DOF) is available. Base on the established kinematic model of a single leg in terms of POE formula of screw theory, several typical patterns of walking motion planning are implemented and verified by the ADAMS-based simulation. In order to show a good maneuverability and potential manipulation capability of the quadruped robot as a parallel manipulator, the gait planning reflecting two rotating motion patterns (including the rotating motion and walking motion) is modeled and simulated by kinematics of the equivalent parallel manipulators. Finally, a prototype of the quadruped robot has been built. Experimental test shows the practical walking and rotating ability as desired.