bluuebunny/crossref_metadata_2025 huggingface dataset:
Surrogate Modeling of Complex Systems Using Adaptive Hybrid Functions
Authors: Zhang Jie , Chowdhury Souma , Messac Achille , Zhang Junqiang , Castillo Luciano
Published: June 2012

This paper explores the effectiveness of the recently developed surrogate modeling method, the Adaptive Hybrid Functions (AHF), through its application to complex engineered systems design. The AHF is a hybrid surrogate modeling method that seeks to exploit the advantages of each component surrogate. In this paper, the AHF integrates three component surrogate models: (i) the Radial Basis Functions (RBF), (ii) the Extended Radial Basis Functions (E-RBF), and (iii) the Kriging model, by characterizing and evaluating the local measure of accuracy of each model. The AHF is applied to model complex engineering systems and an economic system, namely: (i) wind farm design; (ii) product family design (for universal electric motors); (iii) three-pane window design; and (iv) onshore wind farm cost estimation. We use three differing sampling techniques to investigate their influence on the quality of the resulting surrogates. These sampling techniques are (i) Latin Hypercube Sampling (LHS), (ii) Sobol’s quasirandom sequence, and (iii) Hammersley Sequence Sampling (HSS). Cross-validation is used to evaluate the accuracy of the resulting surrogate models. As expected, the accuracy of the surrogate model was found to improve with increase in the sample size. We also observed that, the Sobol’s and the LHS sampling techniques performed better in the case of high-dimensional problems, whereas the HSS sampling technique performed better in the case of low-dimensional problems. Overall, the AHF method was observed to provide acceptable-to-high accuracy in representing complex design systems.
On a Probabilistic View of Commonality for Product Evolution and Reuse
Authors: Pandey Vijitashwa , Thurston Deborah , Mourelatos Zissimos P.
Published: June 2012

Product line commonality has been claimed to be a means to improving efficiency in design and manufacturing of multiple products. Numerous metrics exist in the literature to quantify the level of commonality in a product line. It remains unclear how and why commonality should be measured and accounted for in product design. In this paper, four desired properties of commonality indices are identified: scalability, ability to incorporate subjective information, ease of updating of the index when new information becomes available and applicability in assessing reuse potential. We propose metrics based on a probability based interpretation of commonality to account for these requirements. With the use of results in probability theory we show how the metric exhibits properties missing in other metrics proposed in the literature. The metric also takes into account generations of products easily and can be used to measure their reusability. We demonstrate the method using a slider-crank mechanism product line example.
Feature Extraction and Abnormality Detection in Autonomic Regulation of Cardiovascular System
Authors: Jalali Ali , Nataraj C. , Butchy Margaret , Ghaffari Ali
Published: June 2012

The objective of this study is to develop an efficient methodology for classifying patients suffering any type of blood pressure dysregulation from healthy subjects. Four features of malfunctions in blood pressure regulation are introduced, and a criterion is proposed for each feature to evaluate and distinguish patients from healthy subjects. The evaluated features are based on the analysis of difference between data related to healthy subjects and those collected from patients. The proposed criteria are implemented on a group of healthy and patient subjects by collecting their systolic blood pressure (SBP) and their heart rate (HR) time series. The proposed method is applied on three different groups of subjects each containing four healthy and eleven patients. It is shown that the algorithm properly detects the status of all fifteen subjects in one group and fourteen subjects in two groups. The results obtained indicate that the selected features have remarkable capability in detection of blood pressure dysregulation.
Learning Stylistic Desires and Generating Preferred Designs of Consumers Using Neural Networks and Genetic Algorithms
Authors: Tseng Ian , Cagan Jonathan , Kotovsky Kenneth
Published: June 2012

Consumers have different ideas of what makes a design stylish. Some consumers may want a sporty looking car, while others may want a rugged looking or a fuel-efficient looking car. Can computers learn what it means to satisfy those style-based goals and use this knowledge to generate designs that target style-based goals in design? An experiment was conducted where participants were asked to rate computer generated car profiles for sportiness, ruggedness, beauty, and fuel efficiency. This survey data is used as an indicator of consumer stylistic form preferences, and was used to train Artificial Neural Networks (ANN) for each of the four rating categories. The resulting ANNs were then inverted using a Genetic Algorithm (GA) in order to generate new designs that elicit targeted style goals from consumers.
Voronoi-Based Coverage Control for Multi-Quadrotor UAVs
Authors: Sharifi Farid , Zhang Youmin , Gordon Brandon W.
Published: June 2012

This paper investigates the problem of covering an environment using a group of quadrotor Unmanned Aerial Vehicles (UAVs) based on locational optimization techniques to assign Voronoi regions to vehicles. In comparison with the standard coverage control problems for single integrator agents, we design a planar position controller for UAVs to spread out over an environment to provide coverage. The stability of entire system is guaranteed using LaSalle’s invariance principle, and numerical simulation is provided to show the effectiveness of the proposed method.
Emotion and Process Quality
Authors: Fukuda Shuichi
Published: June 2012

Traditionally quality has been discussed mainly from the standpoint of functions and from the standpoint of a product, because engineering up to now has focused major efforts on how we can produce better quality products. Value was evaluated in terms of product quality. But when we come to think that not only products but processes also yield value, we should consider process quality as well. Behavior economics points out the importance of experience value. This is nothing other than process value. But what they discuss is value in use. We, engineers, should remember we can create experience through design and manufacturing and even through maintenance. Products get to fit us better with use and our attachment to them grows with time. This is breaking in but to express it in another way, it is nothing other than deterioration. Maintenance, for example, is not just an activity to restore deteriorating functions back to the design requirements. But rather it is an activity to break in our products. These process values are very much associated with emotion. This paper points out the importance of process value and how emotion plays an important role in process quality management. It is also pointed out that pattern classification approach is very effective for processing emotional quality.
Tool Contact Maps by Rectangular Grid Decomposition
Authors: Aras Eyyup
Published: June 2012

This paper is intended to contribute to ongoing research [1–3] in geometric modeling of the virtual machining. In geometric modeling the tool paths are verified by performing the machining simulations and also the cutter workpiece engagements (CWEs) are extracted. CWE geometry is a key input to force calculations and feed rate scheduling in milling operations. Finding these engagements is challenging due to the complicated and changing intersection geometry between the cutter and the in-process workpiece. This paper presents a discrete model based methodology for extracting CWEs generated during a multi axis machining of free form surfaces using a range of different types of milling tools. In this method the in-process workpiece is represented by a set of z-axis aligned rectangular grids. Each grid is made up of four planes, with their normals aligned with respect to the x and y-axis of the Cartesian coordinate system. In developing the methodology the parametric representations of the automatically programmed tool (APT)-type milling cutters are used. The milling tool surfaces are decomposed into circles. During the material removal process only some portions of those circles which are called the engagement arcs may contact the in-process workpiece. To find the geometric limits of those arcs the concept of the feasible contact surface is utilized. The CWE extraction simulation is performed through intersecting those arcs with the planes of each rectangular grid. Thus the intersection calculations reduce to circle/plane intersections which can be performed analytically for the geometry found on milling cutters. To be used in the force model, the CWE boundaries are mapped from Euclidean 3D space to a parametric space defined by the engagement angle and the depth-of-cut for a given tool geometry. Then using a sort algorithm the neighboring engagements in the same arc level are combined.
Context-Specific Experience Sampling for User Emotion Research
Authors: Kim Yong Se , Hong Yeon Koo , Kim Sun Ran , Kim Jin Hui
Published: June 2012

Though benefits of Experience Sampling (ES) for experience design and research are apparent, the method has not been widely used in the field. As for the reasons, the following are prominent: 1) methodological issues as conventional ES obtains contextual experience information from the participants’ description of the context), and 2) a lack of theoretical framework enabling researchers to carry systematical analysis and extraction of meaningful experiences. In order to deal with these issues, the researchers have created an adapted ES model, named ‘Context-Specific Experience Sampling’, by which integration of a rigorous data collection and analysis processes is made possible. The model provides explanations of how to gather context-specific user experience information and extract key themes and attributes from the data pool. This approach, manifesting divergent-to-convergent features, is described as ‘experience pooling, sorting, and extracting’ which fall under the concept of ‘experience processing’. This paper details the structure and procedure of the model illustrating it with examples from a small scale lighting ambiance study of fashion stores.
Bifurcation of Nonlinear Normal Modes by Means of Synge’s Stability
Authors: Lee Young S. , Chen Heng
Published: June 2012

We study bifurcation of fundamental nonlinear normal modes (FNNMs) in 2-degree-of-freedom coupled oscillators by utilizing geometric mechanics approach based on Synges concept, which dictates orbital stability rather than Lyapunovs classical asymptotic stability. Use of harmonic balance method provides reasonably accurate approximation for NNMs over wide range of energy; and Floquet theory incorporated into Synges stability analysis predicts the respective bifurcation points as well as their types. Constructing NNMs in the frequency-energy domain, we seek applications to study of efficient targeted energy transfers.
Amplitude and Frequency Dependence of the Signal-to-Noise Ratio in LDV Measurements
Authors: O’Malley Patrick F. , Vignola Joseph F. , Judge John A.
Published: June 2012

When making measurements using many sensors, it is expected that, within normal operating ranges, the signal-to-noise ratio is approximately linear (i.e. 20 dB/decade). This generality does not hold, however, when making measurements using a laser Doppler vibrometer (LDV). If the velocity of the target of an LDV measurement increases by an order of magnitude, changes in the speckle pattern will introduce noise into the measurand. An experiment was conducted using an LDV system to measure the velocity response of a speaker excited over several orders of magnitude in both frequency and amplitude. Results are presented showing the relationship between signal-to-noise ratio and vibration amplitude.
Wave Propagation in Membrane-Based Nonlinear Periodic Structures
Authors: Narisetti Raj K. , Ruzzene Massimo , Leamy Michael J.
Published: June 2012

Wave propagation in a periodic structure, formed by membrane elements on nonlinear elastic supports, is studied using a finite element discretization of a single unit cell followed by a perturbation analysis. The study is motivated in part by the need to study the dynamic behavior of micro-machined ultrasonic transducers (CMUTs). The requisite small parameter in the system arises from the ratio of the membrane to flexible support stiffness. The perturbation approach recovers linear Bloch formalism at first order, and amplitude-dependent dispersion corrections at higher orders. The procedure is used to generate weakly nonlinear band diagrams, which can in turn be used to identify amplitude-dependent bandgaps and group velocities. These diagrams also reveal that the strongest amplitude dependency occurs in high-frequency optical modes. Ultimately, the predicted dispersion behavior will be useful in assessing inter-element coupling and identifying effective excitation strategies for actuating CMUTs.
Robust Structural Design Optimization Under Non-Probabilistic Uncertainties
Authors: Liu Jiantao , Gea Hae Chang , Du Ping An
Published: June 2012

Robust structural design optimization with non-probabilistic uncertainties is often formulated as a two-level optimization problem. The top level optimization problem is simply to minimize a specified objective function while the optimized solution at the second level solution is within bounds. The second level optimization problem is to find the worst case design under non-probabilistic uncertainty. Although the second level optimization problem is a non-convex problem, the global optimal solution must be assured in order to guarantee the solution robustness at the first level. In this paper, a new approach is proposed to solve the robust structural optimization problems with non-probabilistic uncertainties. The WCDO problems at the second level are solved directly by the monotonocity analysis and the global optimality is assured. Then, the robust structural optimization problem is reduced to a single level problem and can be easily solved by any gradient based method. To illustrate the proposed approach, truss examples with non-probabilistic uncertainties on stiffness and loading are presented.
The Development of a Framework for Investigating the Effectiveness of Capstone Course Curricular Changes
Authors: Sherrett Ben , Parmigiani John
Published: June 2012

Capstone courses are an integral part of the educational experience in undergraduate engineering programs. However, such courses tend to be challenging in nature for course instructors as many of the features of the capstone course contrast starkly with typical courses in the engineering curriculum. As in any field, communication of effective strategies is crucial as the capstone course community seeks to better their practices. With this goal in mind, the question arises: How does one instructor convince her or his colleagues that a teaching practice implemented at the home university is (i) truly effective, and (ii) can be transferred to other universities with similar results? While effectiveness may be measured in other more traditional courses by simply looking at assignment and test grades, the complexity associated with the capstone course adds ambiguity and complex interrelations that require a more thoughtful and detailed inquiry. This work explains such a framework for evaluating the effectiveness of capstone course changes implemented over the past seven years at Oregon State University. The evaluation framework relies on results from faculty, sponsor, and student surveys as well as sponsor participation data, student work products, course evaluations, and student grades over the period of the past seven years. This work outlines the framework and discusses future plans of implementation of the research project.
Characterizing the Influence of Land Configuration on the Optimal Wind Farm Performance
Authors: Chowdhury Souma , Zhang Jie , Messac Achille , Castillo Luciano
Published: June 2012

The development of large scale wind farms that can produce energy at a cost comparable to that of other conventional energy resources presents significant challenges to today’s wind energy industry. The consideration of the key design and environmental factors that influence the performance of a wind farm is a crucial part of the solution to this challenge. In this paper, we develop a methodology to account for the configuration of the farm land (length-to-breadth ratio and North-South-East-West orientation) within the scope of wind farm optimization. This approach appropriately captures the correlation between the (i) land configuration, (ii) the farm layout, and (iii) the selection of turbines-types. Simultaneous optimization of the farm layout and turbine selection is performed to minimize the Cost of Energy (COE), for a set of sample land configurations. The optimized COE and farm efficiency are then represented as functions of the land aspect ratio and the land orientation. To this end, we apply a recently developed response surface method known as the Reliability-Based Hybrid Functions. The overall wind farm design methodology is applied to design a 25MW farm in North Dakota. This case study provides helpful insights into the influence of the land configuration on the optimum farm performance that can be obtained for a particular site.
Implementation of an Algorithm for the Direct Solution of Optimal Control Problems
Authors: Fabien Brian C.
Published: June 2012

This paper presents the implementation of a numerical algorithm for the direct solution of optimal control and parameter identification problems. The problems may include differential equations that define the state, inequality constraints, and equality constraints at the initial and final times. The numerical method is based on transforming the infinite dimensional optimal control problem into a finite dimensional nonlinear programming problem. The transformation technique involves dividing the time interval of interest into a mesh that need not be uniform. In each subinterval of the mesh the control input is approximated using a piecewise polynomial. In particular, the control can be approximated using: (i) piecewise constant, (ii) piecewise linear, or (iii) piecewise cubic polynomials. The explicit Runge-Kutta method is used to obtain an approximate solution of the differential equations that define the state. With the approach used here the states do not appear in the nonlinear programming (NLP) problem. As a result the NLP problem is very compact relative to other numerical methods used to solve nonlinear optimal control problems. The NLP problem is solved using a sequential quadratic programming (SQP) technique. The SQP method is based on minimizing the L1 exact penalty function. Each major step of the SQP method solves a strictly convex quadratic programming problem. The paper also describes a simplified interface to the computer programs that implement the method. An example is presented to demonstrate the algorithm.
Numerical Investigation of Biodiesel Production in Capillary Microreactor
Authors: Han Wei , Charoenwat Rachaneewan , Dennis Brian H.
Published: June 2012

Synthesis of biodiesel through transesterification of vegetable oil with methanol has been experimentally studied in different types of microreactors though detailed numerical simulation has not yet been presented. The capillary microreactor has the potential to greatly intensify mass transfer between immiscible fluids that would result in higher chemical reaction rates. A segmented flow pattern of oil and methanol forms within the reactor. It has been shown experimentally that the two phase flow has dramatic benefits on the intensification of mass transfer and heat transfer. Such reactors have been proposed for the synthesis of biodiesel and detailed understanding of flow dynamics and chemical kinetics would be useful for process optimization. This paper presents a mathematical model and numerical solution for the synthesis of biodiesel in a capillary reactor. The model represents the unsteady incompressible viscous non-equilibrium chemically reacting flow. The equations are discretized with the finite element method (FEM) and solved to demonstrate the flow behavior and concentration distribution of each chemical species within two phases; different residence time will be obtained with different volume flow rate as well. Information about efficient computational treatment of the model will also be presented.
A Numerical Scheme for a Class of Parametric Problem of Fractional Variational Calculus
Authors: Agrawal Om P. , Hasan Md. Mehedi , Tangpong X. W.
Published: June 2012

Fractional derivatives (FDs) or derivatives of arbitrary order have been used in many applications, and it is envisioned that in future they will appear in many functional minimization problems of practical interest. Since fractional derivatives have such property as being non-local, it can be extremely challenging to find analytical solutions for fractional parametric optimization problems, and in many cases, analytical solutions may not exist. Therefore, it is of great importance to develop numerical methods for such problems. This paper presents a numerical scheme for a linear functional minimization problem that involves FD terms. The FD is defined in terms of the Riemann-Liouville definition; however, the scheme will also apply to Caputo derivatives, as well as other definitions of fractional derivatives. In this scheme, the spatial domain is discretized into several subdomains and 2-node one-dimensional linear elements are adopted to approximate the solution and its fractional derivative at point within the domain. The fractional optimization problem is converted to an eigenvalue problem, the solution of which leads to fractional orthogonal functions. Convergence study of the number of elements and error analysis of the results ensure that the algorithm yields stable results. Various fractional orders of derivative are considered and as the order approaches the integer value of 1, the solution recovers the analytical result for the corresponding integer order problem.
On the Development of a Piezoelectric-Actuated Compliant Brake Mechanism for Modular Robots
Authors: Thorne Chris E. , White Paul J. , Yim Mark
Published: June 2012

A bistable brake mechanism can be beneficial to the development of an energy efficient module for a modular reconfigurable robot. These robots are comprised of many repeated units. To date, research efforts have focused on increasing specific torque to expand the capabilities of modular robots. In this work, we present the continued development of energy efficient joint-locking mechanisms, specifically a piezoelectric actuator and a compliant transmission. The design and manufacturing of the mechanism is presented along with a model for predicting the static and dynamic behavior of the device. We also present experimental results that indicate better performance in terms of power consumption, specific torque, and bandwidth than is possible with comparable devices that utilize magnetic particles and electromagnetically-actuated disc and drum brakes. When fully implemented, this joint-locking mechanism will lead to three critical improvements in the area of modular robotics: decreased energy expenditure per non-active module, increased ability to utilize dynamic motion due to less reliance on highly-geared servo motors, and improved ability to maintain configurations with high mechanical advantage.
Characterization of Structural Dynamics With Uncertainty by Using Gaussian Processes
Authors: Xia Z. , Tang J.
Published: June 2012

An efficient way to capture the dynamic characteristics of structural systems with uncertainties has been an important and challenging subject. While such characterization is valuable for structural response predictions, it could be impractical in many application situations where a sufficiently large sample is expensive or unavailable. In this paper, Gaussian process regression models are employed to capture structural dynamical responses, especially responses with uncertainties. When Gaussian processes are used to make predictions for responses with uncertainties, the sampling costs can be significantly reduced because only a relatively small set of data points is needed. With no loss of generality, applications of Gaussian process regression models are introduced in conjunction with Monte Carlo sampling. This approach can be easily generalized to situations where data points are obtained by other sampling techniques.
Fault Tolerant Control Applied to a Quadrotor Unmanned Helicopter
Authors: Li Tong , Zhang Youmin , Gordon Brandon
Published: June 2012

In this paper, two sliding mode based fault tolerant control (SM-FTC) strategies are designed, implemented and flight-tested in a physical quadrotor unmanned helicopter under the propeller damage and actuator fault conditions. Sliding model control (SMC) is well known for its capability of handling uncertainty and is expected to be a robust controller. Based on the concept of sliding mode control, both passive and active fault tolerant controls have been designed and experimentally tested on a quadrotor UAV (unmanned aerial vehicle) test-bed, known as Qball-X4, available at Concordia University in the presence of actuator faults and propeller damages. These two types of controllers are carried out and compared through theoretical analysis, simulation, and experimental flight tests on the quadrotor UAV system. Good control performance has been achieved in the presence of actuator faults and propeller damages.
Multibody Dynamics Model for Predicting the Vibration Response and Transient Tooth Loads for Planetary Gear Systems
Authors: Wasfy Tamer M. , Stark Michael Lee
Published: June 2012

A high-fidelity multibody dynamics model for predicting the transient response of planetary gear trains is presented. The model supports an arbitrary number of gears, stages and arms. The model accurately accounts for the effects of gear tooth stiffness/damping/friction and tooth backlash. The multibody system representing the system is modeled using rigid bodies, revolute joints and rotational actuators. A penalty model is used to impose the joint and normal contact constraints. The normal contact penalty stiffness and damping are used to model the tooth stiffness and damping. The contact model detects contact between discrete points on the surface of a gear tooth (master contact surface) and a polygonal surface representation of the mating gear tooth (slave contact surface). A recursive bounding box/bounding sphere contact search algorithm is used to allow fast contact detection. An asperity friction model or an elasto-hydrodynamic lubrication model can be used for the contact friction forces. 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 its predictions of the resonant frequencies of a planetary gear train to those of a previously published steady-state dynamic model. The model can help improve the design of planetary gear boxes including increasing the range of operating speeds, torque capacity and durability.
Bifurcations of a High-Frequency Horizontally Excited Double Pendulum
Authors: Yabuno Hiroshi , Endo Kazuya
Published: June 2012

The bifurcation phenomena produced in a double pendulum under high-frequency horizontal excitation are theoretically and experimentally examined. It has been well known as dynamic stabilization phenomenon that vertical high-frequency excitation can stabilize inverted pendulum. The phenomenon is produced through a sub-critical pitchfork bifurcation. On the other hand, under horizontal high-frequency excitation, the pendulum undergoes a supercritical pitchfork bifurcation and is swung up from the downward vertical position. There have so far been many researches on such dynamics of a single pendulum under the vertical and horizontal high-frequency excitations, but few investigations on multi-degrees-of-freedom system. Also, the utilization of these bifurcations phenomena under the high-frequency excitation is proposed for motion control of underactuated manipulators, but most researches on application is confined to a single pendulum to which a free of two-link underactuated manipulator corresponds. In this paper, toward the development of a three-link underactuated manipulator, we deal with a double pendulum to which two free links of the three-link underactuated manipulator correspond, and theoretically and experimentally investigate bifurcation phenomena in the two pendulums. First, we theoretically predict two pitchfork bifurcation points while increasing the excitation frequency by linear amplitude equations derived using the method of multiple scales. Furthermore, we experimentally examine the swing-up of the pendulums after the first pitchfork bifurcation point and observe that the system has the four types of stable configurations beyond the second pitchfork bifurcation point.
A Parallel GPU Implementation of the Absolute Nodal Coordinate Formulation With a Frictional/Contact Model for the Simulation of Large Flexible Body Systems
Authors: Khude Naresh , Melanz Dan , Stanciulescu Ilinca , Negrut Dan
Published: June 2012

This contribution discusses how a flexible body formalism, specifically, the Absolute Nodal Coordinate Formulation (ANCF), is combined with a frictional/contact model using the Discrete Element Method (DEM) to address many-body dynamics problems; i.e., problems with hundreds of thousands of rigid and deformable bodies. Since the computational effort associated with these problems is significant, the analytical framework is implemented to leverage the computational power available on today’s commodity Graphical Processing Unit (GPU) cards. The code developed is validated against ANSYS and FEAP results. The resulting simulation capability is demonstrated in conjunction with hair simulation.
Toward a Meta-Model of Behavioral Interaction for Designing Complex Adaptive Systems
Authors: Chiang Winston , Jin Yan
Published: June 2012

Future complex engineered systems must be adaptable to, and function in, unpredictable situations, such as deep space or ocean explorations, hazardous waste cleanups, and search-and-rescue missions. To increase system adaptability, various multi-agent system approaches have been developed. From a design point of view, a critical question in developing such systems is: how can system adaptability be designed into complex systems based only on local interactions between (many) simple cells or agents? Although explicit cooperative methods have been applied to answer this question, their limitation in scaling-up has been recognized. In this paper, we introduce a meta-interaction model that can be used as a design approach towards multi-agent complex systems. The approach parameterizes behavioral interactions extended from the Boids swarm intelligence model by introducing dynamical variables into the system. The goal of the meta-interaction model is to provide a mapping for the prediction of collective functionality from local interactions and for the indication of local interactions based on desired functionality. The proposed model is described in detail and a computer simulation based case study of search-and-surround is presented to demonstrate the effectiveness of our proposed approach to designing complex adaptive systems.
Machining and Running Test of High-Performance Face Gear Set
Authors: Tsuji Isamu , Gunbara Hiroshi , Kawasaki Kazumasa , Takami Akiyasu
Published: June 2012

The purpose of this research is to develop a high-performance face gear set for aircraft. The geometrical design method of the face gear has already been proposed, and how to decide an effective engagement area under the design parameter has been clarified. A numerical example is presented based on the proposed method. Before machining test, the modified-tooth was decided by the developed Tooth Contact Analysis (TCA) program in order to control the tooth contact pattern. The influence of alignment error of each axis of gear was investigated using TCA. The designed modified-tooth was processed by the Multi-Tasking machine. Finally, running test was performed at a pinion rotating speed of 970 rpm. The face gear set can be operated continuously at an maximum load torque 1390 N · m, without any trouble. The transmission efficiency reached 98.9% under maximum load torque. This cutting method of the face gear introduces a new degree of freedom for defining optional shapes of tooth modification.
Tooth Root Stresses of Helical Gear Pairs With Unequal and Offset Face Widths
Authors: Wink Carlos H.
Published: June 2012

In this study, tooth root stresses of helical gear pairs with different combinations of face width increase and offsets were analyzed. Contact face width was kept constant. The variables studied were face width and gear faces offset. The well-known LDP – Load Distribution Program was used to calculate tooth root stresses using a finite element model. The results presented show that the face width increase and offset have a significant influence on tooth root stresses. In some cases, increasing face width of one gear pair member resulted in significant increase of tooth root stress of the other member. For gear pairs with unequal and offset face widths, tooth root stresses were mostly affected when face widths were increased to the same direction of the contact line travel direction.
Random Base Excitation of Timoshenko Beam Traversed by Moving Load
Authors: Javid Fahim , Esmailzadeh Ebrahim , Younesian Davood
Published: June 2012

The study of dynamic response of Timoshenko beam traversed by moving load subjected to random base excitation is carried out. By applying the theory of dynamic response of Timoshenko beam as well as finite element theory, beam finite element governing equations of motion are developed and they are solved using Galerkin method. To validate the model, some results of the model are compared with those available in literatures and very close agreement is achieved. The beam is subjected to travelling load and random base excitation in lateral direction simultaneously. Three types of boundary conditions, namely, hinged-hinged, hinged-clamped, and the clamped-clamped ends, are considered and beam dynamic behavior; such as deflection, velocity, and bending moment of beam midpoint, with all so-called boundary conditions are studied. To get better understanding of base excitation effects on the beam dynamic performance, all the results are presented with and without base excitation, in which considerably difference is observed. Moreover, the effect of base excitation on beam with different span-length is monitored.
Measurement and Characterization of Stiction Force in Microstructures With Tapered Features
Authors: Pelzmann Christopher , Saggere Laxman
Published: June 2012

Modeling and measurement of stiction or adhesion due to van der Waals force between microstructures and micro-gripper tools are important for contact-based manipulation and assembly of microstructures. Microfabricated structures commonly feature rough tapered curved surfaces due to undercutting and surface alterations inherent in the microfabrication processes. While several theoretical models exist for calculating adhesive forces between microstructures featuring spherical, cylindrical and flat surfaces, a model for estimating adhesive forces between microstructures featuring tapered curved surfaces is lacking in the literature. This paper presents experimentally measured values of adhesion or pull-off force between a rough tapered curved microstructure from a rough plane surface using a custom micro-cantilever beam as a force sensing mechanism. The paper also introduces an approach to estimate adhesive force between a tapered curved surface and a flat surface by considering the tapered curved surface as a frustum of a cone bound between two cylinders and using the van der Waals force model for cylinders. It is shown that the experimentally measured adhesive force values lie within the upper and lower values of the theoretically estimated van der Waals force values for the two cylinders that define the tapered curved surface geometry.
Sustainable Manufacturing Analysis for Titanium Components
Authors: Eastlick Dane D. , Sahakian Misha V. , Haapala Karl R.
Published: June 2012

Product designers are seeking effective ways to meet customer requirements, government policies, and internal business drivers for sustainability. Sustainable products encompass attributes including recyclable and renewable materials use, low energy consumption, cost competitiveness, and consideration of safety and health concerns. Beyond product attributes, however, sustainable products are cognizant of a broader life cycle perspective, which necessitates consideration of manufacturing and supply chain issues during design. Current life cycle assessment tools are often deficient in assisting design for manufacturing efforts due to coarseness of available process data or even a lack of representative process models. In addition, such tools consider only the environmental impacts and do not account for broader sustainability measures. Research with a titanium component manufacturer is addressing these deficiencies. A unit process modeling-based method is described to assist in strategic decision making to balance cradle-to-gate economic, environmental, and social attributes. A set of metrics is defined and used as a basis for comparison of design alternatives. The method is demonstrated for analysis of titanium component alternatives resulting from design for manufacturing activities. It is shown that this method can assist engineers in developing more sustainable products.
Robust Design Optimization of Ball Grid Array Packaging
Authors: Kim Jae Chang , Choi Joo-Ho , Kim Yeong K.
Published: June 2012

In this paper, comparisons of the design optimization of ball grid array packaging geometry based on the elastic and viscoelastic material properties are made. Six geometric dimensions of the packaging are chosen as input variables. Molding compound and substrate are modeled as elastic and viscoelastic, respectively. Viscoplastic finite element analyses are performed to calculate the strain energy densities (SED) of the eutectic solder balls. Robust design optimizations to minimize SED are carried out, which accounts for the variance of the parameters via Kriging dimension reduction method. Optimum solutions are compared with those by the Taguchi method. It is found that the effects of the packaging geometry on the solder ball reliability are significant, and the optimization results are different depending on the materials modeling.
Cultivating Students’ Ability of Applying Knowledge in Engineering Design Through Course Project
Authors: Qiu Jining , Zhang Bo , Dong Huimin , Gao Yuan
Published: June 2012

The ability to solve engineering design problems using academic knowledge flexibly is essential for mechanical engineering students and is also quality that employers look for. This paper introduces how students could explore and experience the process of mechanical design in the course project of Theory of Machines and Mechanisms (TMM) in Dalian University of Technology (DUT) through sharing the design process of accelerator (gear-box) in wind power generator by one representative team of students in the course project. Firstly, design requirements are set based on industrial need and the choosing of the best scheme of multi-stage gear train is conducted. Following that is the design of kinematic parameters of gears and the evaluation of selected system. Then, a possible solution to control the input speed of the generator is proposed. In the end, a survey to 279 students who participate in the course project shows the importance of course project in cultivating their ability to apply knowledge in design.
Developing an Integrated Model Framework for the Assessment of Sustainable Agricultural Residue Removal Limits for Bioenergy Systems
Authors: Muth David , McCorkle Douglas , Abodeely Jared , Koch Joshua , Nelson Richard , Bryden Kenneth
Published: June 2012

Agricultural residues have significant potential as a feedstock for bioenergy production, but removing these residues from the land can have negative impacts on soil health. Because of this computational tools are needed that can help guide decisions on the amount of agricultural residue that can be sustainably removed. Models and datasets that can support decisions about sustainable agricultural residue removal are available; however, no tools currently exist that are capable of simultaneously addressing all of the environmental factors that can limit the availability of residue for bioenergy production. This paper presents an integrated framework of models and data that provide a coupled a set of environmental process models and databases that can support agricultural residue removal decisions. Specifically the RUSLE2, WEPS, and Soil Conditioning Index models have been integrated together with the disparate set of databases providing the soils, climate, and management practice data required. The integrated system has been demonstrated for two example cases. In the first case the potential impact of agricultural residue removal is explored. In the second case an aggregate assessment of the agricultural residues available bioenergy production in the state of Iowa is performed.
A Flexible Tactile Capacitive Sensor for Slip Detection
Authors: Chung Jinah , Kim Baek-chul , Choi H. R. , Moon H. P. , Lee Y. K. , Nam J. D. , Koo J. C.
Published: June 2012

A tactile sensor for slip detection is necessary for humanlike grasping in robot hand. This paper reports a capacitive tactile slip sensor that can detect slip on the surface of the sensor structure. The newly developed capacitive slip sensor uses acrlyro-nitrile butadien rubber (NBR) as substrate. The presented sensor device in this paper has fingerprint -like structures that are similar with the role of the human’s fingerprint. Movement of the structure that attached on surface of substrate arise capacitance changes, and these are used to detect slip. We carried out slip experiment by prototype of capacitive slip sensor and slip was successfully detected.
Complex Eigenvalue Analysis for Structures With Viscoelastic Behavior
Authors: Chevallier G. , Renaud F. , Dion J.-L. , Thouviot S.
Published: June 2012

This document deals with a method for eigenvalue extraction for the analysis of structures with viscoelastic materials. A generalized Maxwell model is used to model linear viscoelasticity. Such kind of model necessitates a state-space formulation to perform eigenvalue analysis with standard solvers. This formulation is very close to ADF formulation. The use of several materials on the same structure and during the same analysis may lead to a large number of internal states. This article purpose is to identify simultaneously all the viscoelastic materials and to constrain them to have the same time-constants. As it is usually possible, the size of the state-space problem is therefore widely reduced. Moreover, an accurate method for reducing mass and stiffness operators is proposed; The enhancement of the modal basis allows to obtain good results with large reduction. As the length of the paper is limited, only theoretical development are presented in the present paper while numerical results will be presented in the conference.
Dynamic Characteristics of a Machine Tool at Working Positions in Operating Test
Authors: Dong Huimin , Tan Yang , Wang Delun , Ma Yali
Published: June 2012

A machine tool is an assembly structure fitted by some moveable substructures, which the relative motion between the substructures creates normal and limit operating positions. Along with the substructures moving, the distributions of masses, stiffness and damping of the machine in space vary, leading to variety of structure distributions and dynamic properties. For exploring the dynamic properties distributions of machine tools, this paper presents a testing method under practical operational excitations, which is under operating excitations from remaining unbalanced value in the spindle, and collecting vibration signals of time and frequency at the spindle foreside at working positions. To identify resonance characteristics, a judging matrix is established by comparing vibration energy and vibration amplitude at 1st octave. By this method, MDH50 active pole horizontal machining center is tested, and the dynamic characteristics is determined. It reveals that dynamic characteristics of resonance come from the substructure independent resonance and their superposition in operating excitation. For verifying this result, FEA is conducted, in which 20 nodes brick element and spring element are applied to build the model entities and interfaces. The analysis result by FEM is consistent to the testing results. The research provides foundation for how setting up machining programs to avoid the resonance vibration of the machine in the operating.
A Multiscale Approach to Modeling Energy Dissipation in Lap Joints: Comparison of Two Models
Authors: Farhang K. , Segalman D. , Starr M.
Published: June 2012

Energy dissipation in mechanical joints occurs as a result of micro-slip motion between contacting rough surfaces. An account of this phenomenon is especially challenging due to the vast differences in the length and time scales between the macro-mechanical structure and the micron-scale events at the joint interface. This paper considers the contact between two nominally flat surfaces containing micron-scale roughness. The rough surface interaction is viewed as a multi-sphere elastic interaction subject to a periodic tangential force. It combines the Mindlin’s formulation [1, 2] for the elastic interaction of two spheres with the Greenwood and Williamson’s [3] statistical approach for the contact of two nominally flat rough surfaces so as to develop a model for multi-sphere problem in which sphere radii, contact load and the number of spheres in contact can only be known in a statistical sense and not deterministically.
Petri Net-Based Affective-Cognitive Modeling for Product Ecosystem Design
Authors: Xu Qianli , Zhou Feng , Jiao Jianxin Roger
Published: June 2012

Product ecosystem design that emphasizes user experience (UX) with both users’ affective and cognitive aspects lends itself to be of primary importance to value-added user satisfaction. In a product ecosystem, there are human users, multiple products, and the ambience. Thus it involves complex human-product-ambience interactions, which contribute to UX evolution with its ambiguous affective states in conjunction with the cognitive process. In order to optimize UX in the context of product ecosystems, this paper formulates the architecture of product ecosystems with a particular focus on event-driven UX. Further, the causal relations embedded in users’ affective perception and cognitive processes are modeled by a technique called colored dynamic fuzzy Petri net. A subway station design is exemplified to illustrate the proposed methodology. Preliminary results by simulation show the potential and feasibility of the proposed method.