bluuebunny/crossref_metadata_2025 huggingface dataset:
Improving Identifiability in Model Calibration Using Multiple Responses
Authors: Arendt Paul D. , Chen Wei , Apley Daniel W.
Published: June 2012

The use of complex computer simulations to design, improve, optimize, or simply to better understand complex systems in many fields of science and engineering is now ubiquitous. However, simulation models are never a perfect representation of physical reality. Two general sources of uncertainty that account for the differences between simulations and experiments are parameter uncertainty and model uncertainty. The former derives from unknown model parameters, while the latter is caused by underlying missing physics, numerical approximations, and other inaccuracies of the computer simulation that exist even if all of the parameters are known. To obtain knowledge of these two sources of uncertainty, data from computer simulations (usually abundant) and data from physical experiments (typically more limited) are often combined using statistical methods. Statistical adjustment of the computer simulation model to account for the two sources of uncertainty is referred to as calibration. We argue that calibration as it is typically implemented, using only a single response variable, is challenging in that it is often extremely difficult to distinguish between the effects of parameter and model uncertainty. However, many different responses (distinct responses and/or the same response measured at different spatial and temporal locations) are automatically calculated in simulations. As multiple responses generally share a mutual dependence on the unknown parameters, they provide valuable information that can improve identifiability of parameter and model uncertainty in calibration, if they are also measured experimentally. In this paper, we explore the use of multiple responses for calibration.
An Online Genetic Algorithm for Automated Disassembly Sequence Generation
Authors: ElSayed A. , Kongar E. , Gupta S. M. , Sobh T.
Published: June 2012

In this study, we propose an intelligent automated disassembly cell for online (real time) selective disassembly. The cell is composed of an industrial robotic manipulator, a camera, range-sensing and component segmentation visual algorithms. The cell prototype allows for robotic sensory-driven disassembly under uncertainty. An online genetic algorithm model for selective disassembly is also proposed for optimal and near/optimal disassembly sequencing.
Assessing the Effectiveness of Using Graveyard Data for Generating Design Alternatives
Authors: Foster Garrett , Ferguson Scott
Published: June 2012

Modeling to Generate Alternatives (MGA) is a technique used to identify variant designs that maximize design space distance from an initial point while satisfying performance loss constraints. Recent work has explored the application of this technique to nonlinear design problems, where the design space was investigated using an exhaustive sampling procedure. While computational cost concerns were noted, the main focus was determining how scaling and distance metric selection influenced alternative discovery. To increase the viability of MGA for engineering design problems, this work looks to reduce the computational overhead needed to identify design alternatives. This paper investigates and quantifies the effectiveness of using previously sampled designs, i.e. a graveyard, from a multiobjective genetic algorithm as a means of reducing computational expense. Computational savings and the expected error are quantified to assess the effectiveness of this approach. These results are compared to other more common “search” techniques; namely Latin hypercube samplings, grid search, and the Nelder-Mead simplex method. The performance of these “search” techniques are subsequently explored in two case study problems — the design of a two bar truss, and an I-beam — to find the most unique alternative design over a range of different thresholds. Results from this work show the graveyard can be used as a way of inexpensively generating alternatives that are close to ideal, especially nearer to the starting design. Additionally, this paper demonstrates that graveyard information can be used to increase the performance of the Nelder-Mead simplex method when searching for alternative designs.
Combining Separable Monte Carlo With Importance Sampling for Improved Accuracy
Authors: Chaudhuri Anirban , Haftka Raphael T.
Published: June 2012

Monte-Carlo (MC) methods are often used to carry out reliability based design of structures. Methods that improve the accuracy of MC simulation include Separable Monte Carlo (SMC), Markov Chain Monte-Carlo, and importance sampling. We explore the utility of combining SMC and importance sampling for improving accuracy. The accuracy of the estimates is compared for crude MC, SMC, importance sampling and combined method for a composite plate example and a tuned mass damper example. For these examples SMC and importance sampling reduced the error individually by factors of 2 to 5, and the combination reduced it further by about a factor of 2. The results were also compared with the first order reliability method (FORM). FORM was grossly inaccurate for the tuned mass-damper example which has a failure region bounded by safe regions on either side.
Operational Space Algorithm for Flexible Multibody Systems With Generalized Topologies
Authors: Mukherjee Rudranarayan M.
Published: June 2012

Multibody system with flexible and / or rigid bodies are found in various applications of science and engineering. Many of these systems have topological constraints in the form of kinematically closed loop topologies. Similarly, many of these systems have non-holonomic constraints that are either linear or nonlinear in the system velocities. In this paper, an efficient algorithm is presented for simulating the dynamics of multi-body systems of rigid or flexible bodies in generalized topologies with particular emphasis on treatment of topological and non-holonomic constraints. The flexible bodies are modeled using the small deformation large displacement approach. This algorithm achieve linear and logarithmic complexities in serial and parallel implementation and provides robust performance.
A Descriptive Study of Designers’ Tools for Capturing, Reflecting on, and Sharing User Needs and Conceptual Designs
Authors: Oehlberg Lora , Roschuni Celeste , Agogino Alice
Published: June 2012

Designers employ a range of tools to gather, create, explore, sort, and act on user needs and conceptual design information. However, designers work both individually and collaboratively. This research is a descriptive study of technologies employed by designers to individually capture and collaboratively share user needs and conceptual designs. In this paper we examine the range and affordances of tools used by designers, and how they use these tools to share design information. We do this by looking at data gathered in interviews with practicing designers and design researchers, as well as documents produced in undergraduate and graduate-level new product development courses. We gather a wide range of tools from our informants, and analyze them based on sharing semantics and formality. We then introduce a model of sharing as a cycle of capture, reflect and share. Finally, we provide design recommendations for future information tools that support both personal and collaborative user needs and conceptual design information.
Infrastructure Development for Mathematical Modeling the Mechanics of Legged Locomotion
Authors: Mukherjee Rudranarayan M. , Pomerantz Marc
Published: June 2012

Legged locomotion of robotic systems on natural or man-made terrain is a complex, hybrid dynamics phenomenon. Effective design and control of these robots requires mathematical understanding of the system dynamics and exploration over a large design space for feasible design solutions. We are working on the development of a high-fidelity, multi-resolution mathematical modeling infrastructure to study the mechanics of legged locomotion. In this paper, we report some of the recent developments made in our effort. We report the implementation of (i) a multi-rigid body dynamics simulator based on cutting edge algorithms in computational multibody dynamics, (ii) a visualization engine that integrates with the dynamics simulator for real-time visualization of the CAD parts of generic multibody systems, (iii) integration and functionality of the coupled entity of the dynamics simulator and the visualization engine as a stand alone application and (iv) our investigations into massively parallel granular media modeling for ab-initio modeling of the contact mechanics of mobility platforms interacting with natural terrain.
Analysis of Elastic Wave Propagation in Nonlinear Beams
Authors: Abedinnasab Mohammad H. , Hussein Mahmoud I.
Published: June 2012

We derive the exact dispersion relations for flexural elastic wave motion in a beam under finite deformation. We employ the Euler-Bernoulli kinematic hypothesis. Focusing on homogeneous waveguides with constant cross-section, we utilize the exact strain tensor and retain all high order terms. The results allow us to quantify the deviation in the dispersion curves when exact large deformation is considered compared to the small strain assumption. We show that incorporation of finite deformation shifts the frequency dispersion curves downwards. Furthermore, the group velocity increases with wavenumber but this trend reverses at high wavenumbers when the wave amplitude is sufficiently high. At sufficiently high wave amplitudes, the group velocity becomes negative at high wavenumbers. This study on nonlinear homogeneous beams lays the foundation for future development to nonlinear periodic beams.
Online Semantic Knowledge Management for Product Design Based on Product Engineering Ontologies
Authors: Zhu Lijuan , Jayaram Uma , Kim OkJoon
Published: June 2012

The influence of the Semantic Web is growing in many areas. In this paper, the authors present an online Product Design Semantic Knowledge Management System (PD-SKMS) in order to provide a novel approach for presentation, querying/reasoning, and instantiating/updating of knowledge related to product design in an engineering domain. A distributed model is proposed, which is composed of a host hybrid-data repository (HDR), external public linked data sources (EPLD), a Semantic data management engine (SDME), and a web-based user interface layer. Ontologies to preserve knowledge for the product assembly domain are set up as product semantic repositories (PSR) in the host hybrid-data repository. To utilize the legacy design data, a conventional product database (PDB) storing design data is also integrated into this repository. The SDME is able to supply querying/reasoning and instantiating/updating services on PSRs, as well as searching and updating services on PDB. Through web-based user interfaces, engineers on the Web can inquire/contribute design information from/to both PSR and PDB. Additionally, the capability of PD-SKMS is extended by querying on external public linked data sources. It is concluded that the product design environment, constructed on PD-SKMS, allows more knowledge questioners/contributors to be involved in product design tasks in a more interactive manner, and thus greatly improves traditional behaviors for design knowledge sharing and exchanging.
Optimization of a Micro Power Unit
Authors: Khodadad Iman , Ball Len , Bhagat Rahul , Shafieloo Iman , Abdel-Rahman Eihab M. , El-Saadany Ehab , Mansour Raafat , Hajian Arsen
Published: June 2012

In this work, we report on the optimization of a micro power unit. The power unit is comprised of an electromagnetic micro power generator (MPG), power conditioning circuits, and an energy storage component. First, we minimize the mechanical impedance of the MPG by optimizing the size of the seismic mass and support beam as well as re-designing the seismic mass. Second, we investigate the use of off-the-shelf dc-dc converters and custom voltage multipliers and transformers to rectify and step-up the output voltage. We find that transformers were best suited for electromagnetic MPG delivering a rectification efficiency of 75%.
Nonlinear Vibration of Gear Pairs With Tooth Surface Modifications at Primary Resonance Using a Perturbation Method
Authors: Eritenel Tugan , Parker Robert G.
Published: June 2012

An analytical solution for the nonlinear vibration of gear pairs that exhibit partial and total contact loss is found. The gear teeth can have arbitrary tooth surface modifications. Such modifications and dynamic displacements separate parts of gear tooth surface otherwise designed to be in contact. This is partial contact loss. The excitation and the nonlinearity are not specified but are found from the force-deflection function of the gear pair, which comes from independent analysis, such as a finite element model. Fourier and Taylor series expansions of the force-deflection function capture the flexibility, nonlinearity, and the excitation in a few coefficients. The gear elastic behavior includes Hertz contact, bending, and shear. The nonlinearity arises chiefly from tooth surface modifications due to the dependence of contact upon the instantaneous dynamic mesh force. Although this work focuses on gear pairs with tooth surface modifications, the physical system from which the force-deflection function comes is not limited to gear pairs. Sphere/half-space contact vibrations are also analyzed. The dynamic frequency-amplitude relation at the steady-state is found using the method of multiple scales. Comparisons with experiments from the literature on gear vibrations and sphere/half-space contact vibrations verify the method.
Lean Value Creation in the Product Development Process With the Principle of Set Based Concurrent Engineering
Authors: Cai Tianyi , Freiheit Theodor
Published: June 2012

Lean value creation requires a value-adding network of lean activities across the whole Product Development Process (PDP). Management needs to allocate resources and properly control the process to create the value that stakeholders desire. Leading companies in industry have successfully applied Set-Based Concurrent Engineering (SBCE) for lean PDP. In SBCE, designers propose several feasible solutions and develop them relatively independently and in parallel, and then gradually narrow the sets of solutions based on updated project feedback at each stage-gate design review. As an important lean concept with many advantages, SBCE has constraints that can jeopardize lean value creation. For instance, it is unclear how resources are allocated to each stage, different functional teams, and different value creation activities related to different kinds of value, which can cause waste of talent, time, and money. This paper focuses on how resources can be allocated to SBCE by viewing product development activities as value creation cells. Under management control, lean value creation activities use knowledge and other resources to produce valuable design solutions. A mathematical feedback control model is proposed to illustrate how management can invest resources for the value creation process. This model can be used to explore resource allocation to functional teams and processes according to a holistic value creation project development strategy and the optimal creation of lean value.
Dynamic Simulation and Vibration Analysis of a Mechanical Piano Key Actuator
Authors: Masoudi Ramin , Birkett Stephen , Salehian Armaghan
Published: June 2012

Dynamic modeling of a flexible hub-beam system with an eccentric tip mass including nonlinear hysteretic contact is studied in this paper. In reality, the model is intended to represent the mechanical finger of an actuator for a piano key. Developing a device to achieve a desired finger-key contact force profile that realistically replicates that of a real pianist’s finger is the main objective of this research. The proposed actuation system consists of a flexible arm which is attached to a DC brushless rotary motor thorough a hub. The compliant arm behaves as a cantilever beam to which an eccentric tip mass has been attached at its free end. During the piano key stroke, the contact force input from the tip causes the key to rotate and impact the ground through an interface lined with stiff felt to suppress vibrations and noise. Euler-Bernoulli beam theory in conjunction with Lagrange’s method is utilized to obtain the governing equations of motion for the system. The finite element method is used as the discretization procedure for the flexible cantilever beam, which can be considered a distributed parameter system. To include contact dynamics at the stop, the nonlinear hysteretic behavior of felt under compression is modeled in such a way that smooth transitions between loading and unloading stages are produced, thus ensuring accurate response under dynamic conditions, and particularly with partial loading and unloading states that occur during the contact period. Simulation results show excessive vibration is produced due to the arm flexibility and also the rigid-body oscillations of the arm, especially during the period of key-felt contact. To eliminate these vibrations, the system was supplemented with various dashpot models, including a simple grounded rotational dashpot, and a grounded rotational dashpot with a one-sided relation. The results of simulations are presented showing the effect on vibration behavior attributed to these additional components.
Assessment of Energy Potential and Vibration Mitigation of Regenerative Tuned Mass Dampers on Wind Excited Tall Buildings
Authors: Ni Tao , Zuo Lei , Kareem Ahsan
Published: June 2012

Significant amount of inherent vibration energy present in tall buildings as they oscillate under the action of wind is traditionally dissipated into heat by the building damping or damping devices like Tuned Mass Dampers (TMDs) introduced to ensure the structural safety and occupants’ comfort. A portion of this large amount of vibration energy can be harvested if we replace the damping devices with appropriate energy harvesters and power electronics. Accordingly, this paper assesses the potential of harvestable energy from various TMD configurations and evaluates their effectiveness in mitigating building motion. The wind is modeled and simulated using an autoregressive model and the responses of the building to the across- and along-wind load are calculated via spectral approach. The classic TMD, parallel multiple TMDs, and series multiple TMDs are designed based on the decentralized H2 control for optimal stiffness constants and damping coefficients. The performances, namely, the building acceleration, energy potential, and strokes of the TMDs, are studied and compared for different wind speeds and an actual recorded wind event. During high wind events, over 85 K W of power can be harvested from a building used in a benchmark study. TMDs in series configuration with significantly smaller mass than the classic single TMD can achieve similar performance level and energy harvesting with enhanced robustness, but they require larger strokes.
Optimization of a Non-Pneumatic Tire for Reduced Rolling Resistance
Authors: Veeramurthy Mallikarjun , Ju Jaehyung , Thompson Lonny L. , Summers Joshua D.
Published: June 2012

Recently, the development of non-pneumatic tires (NPT) such as the Michelin Tweel is receiving increased attention due to potential advantages over pneumatic tires, including characteristics of rolling resistance (RR). This study focuses on the design of a NPT based on properties of vertical stiffness and rolling energy loss. Using a finite element (FE) model, a parametric study is conducted to study the effect on vertical stiffness and RR response considering two design variables; (a) thickness of the spokes, and, (b) the shear band thickness of the NPT. Using the two geometric variables, a design of experiments (DOE) is performed to study the effect on both RR and vertical displacement. Results from the DOE are used to create response surface models (RSM) for both the objective function (minimal RR) and a constraint on vertical deflection. The analytical RSM function is optimized for minimizing the rolling loss subjected to the given constraint. In addition a design sensitivity study is performed to evaluate the influence of the design variables on the output response. Results indicate that both variables have significant effect on RR, with the shear band thickness having the greater effect.
Sensor Agent Cloud: A Cloud-Based Autonomic System for Physical Sensor Nodes Management
Authors: Chou Yu-Cheng
Published: June 2012

An embedded sensor network is a network of sensor nodes deployed in the physical world that interacts with the environment. Each sensor node is a physically small and relatively inexpensive computer that has one or more sensors. These sensor nodes are often networked, allowing them to communicate and cooperate with each other to monitor the environment. Typically, an embedded sensor network is controlled by its own applications that can access the sensor nodes within the network. On the other hand, the sensor nodes cannot be easily accessed by applications outside of the network. Moreover, even within the same network, different applications might encounter a race condition when they are trying to access a sensor node simultaneously. The issue is related to system management. However, not much research has been done with a focus on the management of sensor nodes. In the past few years, Cloud computing has emerged as a new computing paradigm to provide reliable resources, software, and data on demand. As for resources, essentially, Cloud computing services provide users with virtual servers. Users can utilize virtual servers without concerning about their locations and specifications. With such an inspiration, this paper proposes a system, Sensor Agent Cloud, where users can access the sensor nodes without worrying about their locations and detailed specifications. Sensor Agent Cloud virtualizes a physical sensor node as a virtual “sensor agent”. Users can use and control sensor agents with standard functions. Each sensor agent operates on behalf of its user. The mandatory coordination of these sensor agents is related to the system management. Therefore, Sensor Agent Cloud must be an autonomic system that manages itself with minimum human interference. In addition, Sensor Agent Cloud supports international standard technologies regarding programming and agent communication (C and IEEE FIPA standard). Thus, it is expected that the proposed Sensor Agent Cloud can enhance the applicability and usability of embedded sensor networks in many application areas.
High Resolution Microscopy of SiO2 and the Structure of SiO2-Supported Graphene
Authors: Burson Kristen M. , Yamamoto Mahito , Cullen William G.
Published: June 2012

Graphene has attracted great interest due to its exceptional electrical, mechanical, and chemical properties since its discovery in 2004. Since its first realization, the substrate of choice for graphene exfoliation has been Si wafer with approximately 300 nm thick SiO2 dielectric layer, because it allows 1) direct optical detection of monolayer flakes, and 2) a convenient back gate with dielectric for controlling carrier density in the graphene. However, the amorphous structure of SiO2 and its associated surface roughness has led to ongoing controversy in determining the structure of SiO2-supported graphene. The conductivity of graphene allows scanning tunneling microscopy (STM) to be used to measure its topography, generally allowing its structure to be atomically resolved. In contrast, the insulating SiO2 must be probed with atomic force microscopy (AFM), and this is often done using ambient tapping-mode AFM. STM measurements of graphene on SiO2 generally show greater roughness and finer corrugation than is seen in AFM measurements of SiO2, and this has been interpreted as evidence for “intrinsic” corrugation of the graphene. However, when the energetics of adhesion and elasticity are considered, the idea of intrinsic structure becomes quite controversial for graphene supported on a substrate. Here we show that UHV non-contact AFM (NC-AFM) measurement of SiO2 reveals structure unresolved in previous measurements, and shows both greater roughness and smaller lateral feature size than seen for graphene measured by STM. High-resolution measurement of the SiO2 topography enables an analysis based on the energetics of graphene bending and adhesion, showing that the graphene structure is highly conformal to the SiO2 beneath it. The topographies reported here contrast the atomically-flat crystalline surfaces used in benchmark NC-AFM measurements. They pose unique challenges for measurement resolution, and highlight the very different physical mechanisms which determine resolution in STM vs. NC-AFM. We discuss these issues and our recent efforts at quantitative modeling of the imaging process, with particular focus on the role of van der Waals forces and their contribution to the image signal.
Evaluation of Designs of Shipboard Cathodic Protection Systems Using Boundary Element Modelling Technique
Authors: Wang Yueping
Published: June 2012

Boundary element modelling technique was used to evaluate the performance of the underwater hull impressed current cathodic protection (ICCP) system of a steel-hulled vessel, as part of an investigation of the corrosion failure of the steel hull near the ICCP anodes. The same technique was also used to evaluate the designs of an alternate sacrificial anode cathodic protection system. The modelling results indicated that the existing ICCP system was capable of providing adequate cathodic protection to the underwater hull and appendages if the current demand is less than 2.4 A. Small anode size was found to have a profound effect on the potentials immediately adjacent to the anode, stressing the need for an effective, intact anode shield. Application of paint coating on the bronze propellers could substantially reduce the current demand from the anodes, resulting in less negative potentials adjacent to the anodes. The modelling results also showed that the anode design adopted from a vessel of similar size (<5% difference in all dimensions), which consists of 8 hull mounted aluminum anodes and 4 rudder zinc anodes, would provide adequate cathodic protection for the underwater hull structures of the existing vessel for more than 3 years. The performance of a modified anode placement was also studied in comparison with that of the original anode placement. The results indicated that the anodes in the modified anode placement would not only contribute more uniform current than the anodes in the original anode placement, but also result in the potential profiles that have less variations along the hull form. This modified anode placement would potentially result in a longer service life of the anodes.
Surface Vibration of a Multilayered Elastic Medium due to Harmonic Concentrated Force
Authors: Ojetola Akindeji , Hamidzadeh Hamid
Published: June 2012

Dynamic response of a multi-layer elastic medium subjected to harmonic surface concentrated load is considered. In development of the analytical solution, the three-dimensional theory of elasto-dynamic is utilized for derivation of the governing partial differential equations for each layer. These equations are solved in the Fourier domain by employing the Double Complex Fourier Transform technique. In the analysis, each layer of the medium is assumed to be extended infinitely in the horizontal x and z directions and has uniform depth in the y direction and is considered to be linearly elastic, homogeneous, and isotropic. Utilizing the Integral Fourier Transform, displacements and stresses at any point in each layer can be determined in terms of boundary stresses for each layer. Also, the presented solution provides the relation between stress and displacement vectors for the top and bottom of each layer in matrix notation. By satisfying the compatibility of displacements and stresses for each interface, a propagator matrix relating displacements and stresses at the top of the medium to the bottom interface will be obtained. This relates the displacement and stress vector on the top surface to the bottom interface by eliminating similar information for the other interfaces. In this study, the displacements on the surface of the layered medium are computed for the two cases where the surface of the medium is subjected to a concentrated harmonic vertical or horizontal harmonic force.
Using Brain Computer Interfaces for Geometry Selection in CAD Systems: P300 Detection Approach
Authors: Esfahani Ehsan Tarkesh , Sundararajan V.
Published: June 2012

The purpose of this paper is to explore the potential of brain-computer interfaces as user interfaces for CAD systems. The paper describes experiments and algorithms that use the BCI for selecting different surface of geometrical objects in the CAD systems using the P300 wave. The P300 (P3) wave is an event related potential (ERP) elicited by infrequent, stimuli (target faces flashing). Users wear an electroencephalogram (EEG) headset and try to select a target face of an object. Different faces of the object randomly flash which make the flashing of target face, an infrequent event. The EEG headset collects brain activity from 14 locations on the scalp. The data is analyzed with independent component analysis (ICA) and the discrete wavelet transforms (DWT) to detect the P300 component in the signal. The flashing face which causes the P300 component in the EEG signal is classified as the target face. Using a linear discriminant analysis, the target face is classified correctly with an average accuracy of 73.9%.
Response of a Beam on Nonlinear Viscoelastic Unilateral Foundation and Numerical Challenges
Authors: Bhattiprolu Udbhau , Davies Patricia , Bajaj Anil K.
Published: June 2012

Nonlinear viscoelastic behavior is a characteristic of many engineering materials and also biological tissue, yet it is difficult to develop dynamic models of systems that include these materials and are able to predict system behavior over a wide range of excitations. This research is focused on a specific example system in the form of a pinned-pinned beam interacting with polyurethane foam. Two cases are considered: (1) the beam and foam are glued so that they are always in contact and the foam can undergo both stretching and compression, and (2) the beam and foam are not glued so that the contact region changes with beam motion, and the foam only reacts in compression. Static as well as dynamic forces act on the beam and the Galerkin method is used to derive modal amplitude equations for the beam on polyurethane foundation. In the second case, determination of the loss of contact points is integrated into the solution procedure through a constraint relation. The static responses for both cases are examined as a function of the foam nonlinearity and loading conditions, and three and five mode solutions are compared. The steady state response of the system subject to static and harmonic loads is studied by using numerical integration techniques. Numerical challenges and the accuracy of this approach are discussed. Frequency responses are generated for a range of foam nonlinearities and loading conditions.
Product-Service Systems Representation With Product and Service Elements and a Case Study
Authors: Kim Yong Se , Lee Sang Won , Koh Dong Chan
Published: June 2012

This paper proposes a new systematic methodology to schematically represent a Product-Service System (PSS) with product and service elements for effective PSS design. PSS consists of many product and service elements, which are innovatively connected with each other for satisfying customer needs. Therefore, in order to concretely realize a PSS concept, the detailed service and product elements should be properly defined, represented and configured. In this representation scheme, the service element contains service provider and receiver and their activities. In addition, several product elements are associated with a service element. These service elements and associated product elements are explored with the service blueprint method and PSS functional analysis. The concatenation of those many service and product elements is later conducted based on flows that are defined in the PSS function analysis. The case example is studied and it is demonstrated that this method can help to systematically identify critical service and product elements. In addition, alternative product elements and their configuration to be associated with same service element can be easily conceived and compared with the proposed methodology.
Improved MCMC Method for Parameter Estimation Based on Marginal Probability Density Function
Authors: An Dawn , Choi Joo-Ho
Published: June 2012

In many engineering problems, sampling is often used to estimate and quantify the probability distribution of uncertain parameters during the course of Bayesian framework, which is to draw proper samples that follow the probabilistic feature of the parameters. Among numerous approaches, Markov Chain Monte Carlo (MCMC) has gained the most popularity due to its efficiency and wide applicability. The MCMC, however, does not work well in the case of increased parameters and/or high correlations due to the difficulty of finding proper proposal distribution. In this paper, a method employing marginal probability density function (PDF) as a proposal distribution is proposed to overcome these problems. Several engineering problems which are formulated by Bayesian approach are addressed to demonstrate the effectiveness of proposed method.
Integrated Adaptive Fault Diagnosis and State-Feedback Control for Systems With Constant Actuator Faults and Control Input Constraints
Authors: Fan Jinhua , Zhang Youmin , Zheng Zhiqiang
Published: June 2012

The integrated fault diagnosis and fault-tolerant control problem is studied in this paper for linear systems subject to control input constraints. By using an adaptive observer to estimate the constant actuator fault magnitudes and the states simultaneously, a feedback controller is designed to stabilize the closed-loop system. With upper bounds of the fault amplitudes being proportional to the control limits, the admissible initial conditions and estimation errors are given and bounded by a contractively invariant ellipsoidal set. Matrix conditions are presented for the design of both observer and controller. For computation of the controller gain, a nonlinear programming algorithm is proposed. The ADMIRE (Aero Data Model In Research Environment) model is used to verify the effectiveness of the proposed design techniques.
Shear Compliant Hexagonal Cellular Solids With a Shape Memory Alloy
Authors: Ju Jaehyung , Summers Joshua D.
Published: June 2012

In this study, hexagonal honeycombs with a shape memory alloy (SMA) are explored for super-compliant meso-structural design. A nitianol (NiTi) SMA based shear compliant hexagonal cellular materials are introduced and their elastic properties in shear are investigated. The constitutive relation of SMA and Cellular Materials Theory (CMT) are used to develop analytical constitutive equations of SMA honeycombs under isothermal shear loading. A fixed volume based SMA honeycombs are designed with a target shear modulus, (GA*)12, of 10MPa and minimum uni-axial moduli (E11* and E22*) of 10MPa. About 27 to 70% of elastic shear strains are obtained with NiTi SMA honeycombs when they are designed with a G12* of 10MPa.
Time-Accurate Multibody Dynamics Model for Toroidal Traction Drives
Authors: Yildiz Cagkan , Wasfy Tamer M.
Published: June 2012

A time-accurate multibody dynamics model for predicting the transient response of toroidal traction drives is presented. The model can be used to predict the system’s transient response due to variations in the input speed, variations in the output load, and changing the speed ratio. The model supports half and full-toroidal configurations, multiple transmitters and multiple cavities. The multibody system representing the toroidal drive is modeled using rigid bodies, revolute joints and rotational actuators. A penalty model is used to impose the joint/contact constraints. The contact model detects contact between discrete points on the surface of the transmitter and an analytical surface representation of the input and output shafts’ toroidal surfaces. A recursive bounding sphere contact search algorithm is used to allow fast contact detection. An elasto-hydrodynamic lubrication model is used for the tangential contact traction forces between the transmitter and the toroid. The governing equations of motion are solved along with joint/constraint equations using a time-accurate explicit solution procedure. The model is partially validated by comparing to previously published steady-state models. The model can help improve the design of toroidal continuous-variable transmission systems including increasing the torque capacity and durability.
Equivalent Damage Growth Parameters Using a Simplified Model
Authors: Coppe Alexandra , Pais Matthew J. , Haftka Raphael T. , Kim Nam H.
Published: June 2012

Most damage growth models require accurate stress intensity factor as well as model parameters for predicting damage growth. Depending on geometries and loading conditions, these models become complicated with additional model parameters. This paper shows that a simple model, such as the Paris model, can be used for complex geometries by compensating the error in stress intensity factor with the equivalent model parameters that are different from the true ones. Actual damage growth is simulated using the extended finite element method to model the effects of crack location and geometry on the relationship between crack size and stress intensity factor. The detection process of crack using structural health monitoring systems is modeled by adding random noise and a deterministic bias. The equivalent model parameters are then identified using the least-square-filtered Bayesian method, from which the remaining useful life is estimated. Using three examples, it is shown that the RUL estimates are accurate even when an inaccurate stress intensity factor is used.
A Study on Performance of O-Shaped Seal Ring in LWD Device Using Finite Element Analysis
Authors: Li Xin , Liu Wenjian , Peng Gaoliang , Wang Qiang
Published: June 2012

The severe operating conditions required Logging While Drilling (LWD) devices to withstand the high temperatures and pressures. And the seal capability is one of the most important factors to determine the performance and reliability of LWD device directly. O-shaped seal ring is generally used for mechanical sealing in most LWD devices. To precisely predict the behavior of O-shaped seal ring, in this paper, a Finite Element Analysis (FEA) method is proposed to expose the stress and strain of O-shaped seal ring worked under rigorous conditions. An analysis model, which considers all parts are non-rigid components, is established and the contact balance equation is presented. By using ANSYS, the stress distribution and the deformation of O-shaped seal ring is analyzed and a test case is given.
Study of Start-Up Vibration Response for Oil Whip and Dry Whip Through Hilbert Huang Transform
Authors: Fan Chen-Chao , Syu Jhe-Wei , Pan Min-Chun , Tsao Wen-Chang
Published: June 2012

Oil whip induces self-excited vibration in fluid-handling machines, and what is worse, it can cause self-excited reverse precessional full annular rub, known as “dry whip” which is a secondary phenomenon resulting from a primary cause and may lead to a catastrophic failure of machines; that is, “coincidence of oil whip and dry whip” that occurs repeatedly with constant frequency and amplitude in small clearance cases of fluid-handling machines. Early detection of rub malfunction is essential to avoid damage. Hilbert Huang Transform, which included an empirical mode decomposition and Hilbert spectral analysis, is applied. Hilbert Huang Transform is a great method for analyzing non-linear and non-stationary signals, such as rotor startup signals. Hilbert Huang Transform clearly indicates instability at its initiation stage, and energy concentration changes by different stages. Malfunctions like rub can not observe by Hilbert spectrum. Hilbert spectrum combining full spectrum is developed, as know full Hilbert spectrum, to interpret the rub. The coincidence of oil whip and dry whip is observed definitely through FHS. The advantage of the full Hilbert spectrum is to offer a faster, more efficient method to diagnose fluid-induced instability.
Virtual Reality Enhanced Online Learning Environments as a Substitute for Classroom Instruction
Authors: Wasfy Hatem M. , Wasfy Tamer M. , Peters Jeanne M. , Mahfouz Riham M.
Published: June 2012

In this paper we present the main features of a virtual-reality enhanced online learning environment that can be used to deliver fully automated online courses with an ultimate goal of substituting traditional classroom instruction for many science, technology, engineering and math courses. The learning environment incorporates a high level of interactivity that will make the student an active participant in the learning experience, rather than a passive spectator. Virtual-reality is seamlessly integrated in order to simulate lab experiments, scientific instruments and/or industrial equipment. This will help bridge the gap between real world experience and online learning. The learning environment is illustrated using recently developed online courses for freshman university Physics, welding, CNC machining, and centrifugal pump maintenance.
Dynamic Modeling of an Unmanned Helicopter From Flight Test Data
Authors: Wang Guanlin , Zhu Jihong , Xia Hui
Published: June 2012

Accurately modeling the dynamic characteristics of a helicopter is difficult and time-consuming. This paper presents a new identification approach which applies the modes partition method and structure traversal (MPM/ST) algorithm. The dynamic modes, instead of model parameters of each model structure, are sequentially identified through MPM. The model with the minimum cost function (CF) is chosen from the best model set and is defined as the final model. Real flight tests of an unmanned helicopter are carried out to verify the identification approach. Time- and frequency-domain results of the identified models clearly demonstrate the potential of MPM/ST in modeling such complex systems.
Estimating Ease of Single-Fingered Operations of Hand-Held Appliances With Digital Hand
Authors: Kanai Satoshi , Suzuki Seiya
Published: June 2012

Ergonomic-conscious design of hand-held information appliances greatly strengthens their competitiveness. However, current ergonomic assessments are carried out in the form of “real” user-tests which need many human subjects and expensive physical mockups, and only subjective evaluations are obtained. To solve these problems, in this paper, the Digital Hand where the 3D bone structure, surface skin geometry of the human hand are imitated was developed for quantitatively estimating the ease of single-fingered operations of hand-held appliances. The ease is estimated based on the reachability of a finger tip to several specified operation target points, and on the finger joint angle margin which reflects the mobile range of motions of all operating fingers’ joints. An effective correlation was found between the estimation measures and the subjective comfort ratings in the fingered operations of a SLR camera.
High-Fidelity Modeling of Flexible Timing Belts Using an Explicit Finite Element Code
Authors: Wasfy Tamer M.
Published: June 2012

A time-accurate high-fidelity finite element model for timing belt-drives is presented. The belt is modeled using flexible spatial lumped parameters beam elements. Each finite element belt node can be considered as a rigid body whose contact geometry is used to model the contact surfaces of the belt teeth. The sprockets and pulleys are modeled as rigid bodies. A penalty model is used to impose the joint/contact constraints. An asperity-based friction model is used to model joint/contact friction. A recursive bounding box contact search algorithm is used to allow fast contact detection between contact points on the belt surface (master contact surface) and a polygonal surface representation of the sprockets/pulleys. The governing equations of motion are solved along with joint/constraint equations using a time-accurate explicit solution procedure. The model is partially validated by comparing to a previously published steady-state study where the belt tooth loads over the driven sprocket were experimentally measured. The model can help improve the design of timing belts including increasing the range of operating speeds, reduce the vibrations and noise and increase the drive durability.
Conceptual Design and Analysis of Spherical Mobile Robots With an Omni-Wheel Based Internal Driving Unit
Authors: Kong Xianwen , Doak Ross
Published: June 2012

Spherical mobile robots belong to a class of mobile robots which may have applications ranging from exploration to entertainment. This paper presents our preliminary kinematic study of spherical mobile robots which are driven by an omni-wheel based internal driving unit (IDU). At first, we discuss the conceptual design of spherical mobile robots with an omni-wheel based IDU. Several IDUs are proposed. Then we derive the velocity equation of a spherical mobile robot with an omni-wheel based IDU. Finally, two isotropic configurations of spherical mobile robots with an omni-wheel based IDU are identified. This work lays the foundation for the further investigation on spherical mobile robots with an omni-wheel based IDU.
Application of Nonlocal Theory in Dynamic Pull-In Analysis of Electrostatically Actuated Micro and Nano Beams
Authors: Ahmadian M. T. , Pasharavesh Abdolreza , Fallah Ali
Published: June 2012

One of the most important phenomena related to electrically actuated micro and nano electromechanical systems (MEMS\NEMS) is dynamic pull-in instability which occurs when the electrical attraction and beam inertia forces are more than elastic restoring force of the beam. According to failure of classical mechanics constitutive equations in prediction of dynamic behavior of small size systems, nonlocal theory is implemented here to analyze the dynamic pull-in behavior. Equation of motion of an electrostatically actuated micro to nano scale doubly clamped beam is rewritten using differential form of nonlocal theory constitutive equation. To analyze the nonlocal effect equation of motion is nondimentionalized. Governing partial differential equation is transformed to an ordinary differential equation using the Galerkin decomposition method and then is solved implementing differential quadrature method (DQM). Change of dynamic pull-in voltage with respect to size change is investigated. Results indicate as the beam length decreases dynamic pull-in voltage increases due to nonlocal effect and the difference with clasical mechanics results is up to 20% for nano beams.
Modeling and Analysis of Concrete-Filled Steel Structure Under Aircraft Impact
Authors: Huo Jin , Hu Zirong , Sun Yuping
Published: June 2012

Concrete-filled steel structures (SC), or called steel concrete composite structures are composed of steel plates and reinforced concrete. This kind of structures has demonstrated more effective against blast and impact loads, and has been used in risk-sensitive structures such as the nuclear electric power plant and other critical constructions. The comprehensive modeling and analysis is performed in this paper for the full scale SC panel against aircraft impact after the testing results of 1/7.5 scaled model was reviewed and correlated. The methodology, modeling approach, and mesh density sensitivity investigation is presented.