bluuebunny/crossref_metadata_2025 huggingface dataset:
Plug-In Hybrid Electric Vehicle Battery Selection for Optimum Economic and Environmental Benefits Using Pareto Set Points and PSAT™
Authors: Shahi Shashi K. , Wang G. Gary
Published: March 2011

Plug-in hybrid electric vehicles (PHEVs) have the potential to reduce green house gases emissions and provide a promising alternative to conventional internal combustion engine vehicles. However, PHEVs have not been widely adopted in comparison to the conventional vehicles due to their high costs and short charging intervals. Since PHEVs rely on large storage batteries relative to the conventional vehicles, the characteristics and design issues associated with PHEV batteries play an important role in the potential adoption of PHEVs. Consumer acceptance and adoption of PHEVs mainly depends on fuel economy, operating cost, operation green house gas (GHG) emissions, power and performance, and safety among other characteristics. We compare the operational performance of PHEV20 (PHEV version sized for 20 miles of all electric range) based on fuel economy, operating cost, and greenhouse gas (GHG) emissions through Pareto set point identification approach for 15 different types of batteries, including lithium-ion, nickel metal hydride (NiMH), nickel zinc (NiZn), and lead acid batteries. It is found that two from 15 batteries dominate the rest. Among the two, a NiMH (type ess_nimh_90_72_ovonic) gives the highest fuel economy, and a lithium-ion (type ess_li_7_303) yields the lowest operating cost and GHG emissions. From comparing nine batteries that are either on or close to the Pareto frontier, one can see that lithium-ion and NiMH batteries offer better fuel economy than lead-acid batteries. Though lithium-ion batteries bear clear advantage on operating costs and GHG emissions, NiMH and lead-acid batteries show similar performances from these two aspects.
Precision-Based Robot Kinematics Design for Microassembly Applications
Authors: Das Aditya N. , Popa Dan O.
Published: March 2011

The kinematics of a robotic manipulator, including the type of joints, actuators, and other geometric parameters significantly affects its precision (or positioning uncertainty) at the end-effector. Modeling and prediction of these uncertainties can provide useful insight and serve as design guidelines for precision manipulators that are used in micro and nanomanufacturing. Of particular interest are micro scale assembly scenarios where the tolerance budgets are stringent and precision requirements are high, but there is little space for extensive sensor feedback due to a small work volume. In this paper, we investigate the effect of parametric uncertainties in a serial robot chain on overall positioning uncertainty at the end-effector. Two types of errors are considered: static errors due to misalignment and link parameter uncertainties, and dynamic errors due to inaccurate motion of individual links. Using uncertainty metrics we compare the precision of several different robot kinematic chain configurations.
Design of a Novel Human-Computer Interface to Support HCD Application
Authors: Mengoni Maura , Colaiocco Barbara , Germani Michele , Peruzzini Margherita
Published: March 2011

The importance of Human-Centered Design (HCD) drives research toward the development of new UIs (User Interfaces) in order to predict human interaction with products at the early design stages. Virtual Reality (VR) allows carrying out usability tests on virtual prototypes to investigate users’ cognitive and affective response. Application problems regard with the reproduction of synaesthesia qualities in order to make the information processing similar to the one obtained by real sensory stimulation. While visualization technologies seem to be mature enough to overcome the above mentioned limitation, tactile devices are still far from properly simulating materials properties. In this context, the present work aims at structuring and applying a systematic approach to conceive, define and develop a novel VR-based technology, called I-perTouch. The goal is to stimulate the skin mechanoreceptors to generate a meaningful tactile sensation about materials softness, friction and roughness. The system can be also integrated with imaging and sound technologies to create a multi-sensorial product experience. The preliminary architecture results from the analysis of human tactile perception and the benchmark of available simulation devices and techniques. This paper contributes to discuss current issues of existing VR-based technologies in supporting HCD applications and to address technical developments toward the creation of a reliable system for texture perception.
Finding the Shortest Path for a Mobile Robot With Two Actuated Spoke Wheels Based on Variable Kinematic Configurations
Authors: Wang Ya , Hong Dennis
Published: March 2011

Strategies for finding the shortest path for a mobile robot with two actuated spoke wheels based on variable kinematic configurations are presented in this paper. The optimal path planning strategy proposed here integrate the traditional constrained path planning tools and the unique kinematic configuration spaces of the mobile robot IMPASS (Intelligent Mobility Platform with Actuated Spoke System). IMPASS utilizes a unique mobility concept of stretching in or out individually actuated spokes in order to perform variable curvature radius steering using changing kinematic configuration during its movement. Due to this unique motion strategy, various kinematic topologies produce specific motion characteristics in the way of curvature radius-variable steering. Instead of traditional differential drive or Ackerman steering locomotion, combinational path geometry methods, Dubins’ curve and Reeds and Shepp’s curve are applied to classify optimal paths into known permutations of sequences consisting of various kinematic configurations. Numerical simulation is given to verify the analytical solutions provided by using Lagrange Multiplier.
Kinematic Analysis of a Five-Legged Mobile Robot
Authors: Pac Muhammed R. , Popa Dan O.
Published: March 2011

Legged robots are more maneuverable, and can negotiate rough terrain much better than conventional locomotion using wheels. However, since the kinematic or dynamic analysis of such robots involves closed chains, it is typically more difficult to investigate the impact of design changes, such as the number, or the design of its legs, to robot performance. Most legged robots consist of 4 legs (quadrupeds) or 6 legs (hexapods). This paper discusses the kinematic analysis of an unconventional, symmetrical 5-legged robot with 2-DOF (Degrees Of Freedom) universal joints in each leg. The analysis was carried out in order to predict the mobility of the upper body platform, and investigate the number of robot actuators needed for mobility. The product of exponentials formulation with respect to the local coordinate frames is used to describe the twists of the joints. The analysis is based on the idea that the robot body platform along with the legs can be considered instantaneously as a parallel robot manipulating the ground. Hence, the analysis can be done using the Jacobian formulation of parallel robots. Simulation results confirm the mobility analysis that the robot can have at most 3-DOF for the body and that these freedoms are coupled rotations and translations in 3D space also with a dependence on the configuration of the robot.
Forward and Inverse Displacement Analysis of an Actuated Spoke Wheel Robot With Two Spokes and a Tail Contact With the Ground
Authors: Ren Ping , Hong Dennis
Published: March 2011

Intelligent Mobility Platform with Active Spoke System (IMPASS) is a unique wheel-leg hybrid robot that can walk in unstructured environments by stretching in or out three independently actuated spokes of each wheel. The latest prototype of IMPASS has two actuated spoke wheels and one passive tail. In order to maintain its stability, the tail of the robot is designed as a rigid shell with a geometrically convex surface touching the ground. IMPASS is considered as a mechanism with variable topologies (MVTs) due to its metamorphic configurations. Its motions on the ground, such as steering, straight-line walking and other combinations, can be uniformly interpreted as a series of configuration transformations. Among all cases of its topologies, the cases with two spokes and the tail in contact with the ground possess two d.o.f and contribute the most to its ground motion. To fully understand the characteristics of such topologies, the forward and inverse displacement analysis is developed for these cases, with the polynomial equations derived. Numerical solutions from simulation are present to validate their formulation. These results lay the kinematics foundation for the motion monitoring and planning of IMPASS. It also contributes to the design optimization of the tail’s surface geometry to improve its adaptability on uneven terrains.
A Unified Conjugation Theory for Planar Transmission
Authors: Dong Huimin , Ting Kwun-Lon , Liu Jian , Wang Delun
Published: March 2011

The paper presents a general and versatile model describing the kinematic and geometric properties relating the centrodes, the conjugate curves, and the path of contact in a transmission through direct contact between any bodies. From a prescribed motion transmission and a desired path of contact, the characteristics of the conjugate tooth profiles, such as sliding ratio, tooth curvature, induced tooth curvature, conjugate boundary, and interference can be explicitly expressed even before the tooth profiles are obtained. The model is made possible by expressing the path of contact with the Frenet frame on the centrodes. The paper establishes a general theory suitable for optimal tooth profile design. The model is applicable in situations with constant or various transmission ratio as well as constant or various center distance.
Multi-Resolution Cutting Force Prediction Using a Quad-Tree Decomposition for Cutter/Workpiece Engagements
Authors: Yip-Hoi Derek
Published: March 2011

Virtual Machining (VM) is the use of computers to simulate the physics of machining processes. It can be used to effectively identify problems in machining complicated workpieces and in optimizing processes. At the heart of VM is the ability to predict the cutting forces generated as the tool generates chips at the tool workpiece interface. For these predictions to be realistic two things are necessary. First, accurate representations of how the cutter engages the workpiece need to be generated along each toolpath under consideration. This is referred to as the Cutter/Workpiece Engagement (CWE). Second, a force model is needed that integrates the contribution from each element within the CWE. In this paper a new technique for integrating the force contributions is presented. It utilizes a Quad-Tree representation for the CWE. This representation provides several advantages over other approaches for integrating the force contributions. Amongst these is the ability to represent the aggregated force at different resolutions. This has the potential to reduce the time required to perform a simulation by scanning a tool path at a lower resolution to bound intervals where heavy engagements are encountered. These intervals can then be analyzed at a higher resolution for greater accuracy. Examples are presented using CWEs extracted for 2 1/2D milling operations from a component modeled on a leading CAD/CAM system.
The Effects of Open Innovation on Collaboration and Knowledge Sharing in Student Design Teams
Authors: Koch Michael D. , Schulte Richard J. , Tumer Irem Y.
Published: March 2011

As the need to innovate more creatively and effectively becomes increasingly apparent in engineering design, powerful open design tools and practices have emerged that are allowing organizations and firms to tap an already vast pool of skills, knowledge and intellect to solve complex design problems. The need for engineering design educators to bring these new trends into the classroom continues to grow as the industry for which students are being prepared begins to revamp its design strategies and practices in the pursuit of more openly accessible information infrastructures. By conducting an experimental study of over 25 student design groups in an undergraduate design engineering class, our team was able to gauge the relevance and utility of collaboration and knowledge sharing between and within design groups. Specifically, issues and opportunities were identified to help bring engineering and design education in line with the increasingly networked and distributed professional engineering environment that students will be enter upon graduation.
On the Extension of a Fourier Descriptor Based Method for Four-Bar Linkage Synthesis for Generation of Open and Closed Paths
Authors: Wu Jun , Ge Q. J. , Gao Feng , Guo W. Z.
Published: March 2011

In an earlier work, we have presented an efficient method for synthesizing crank-rocker mechanisms that are capable of generating perceptually simple and smooth low-harmonic closed curves. In this paper, we seek to extend this approach to the synthesis of four-bar linkages for the generation of open curves. Instead of using Fourier transform that requires a function to be defined over the entire period, we combine finite Fourier series in a curve-fitting scheme for the approximation of periodic as well as non-periodic paths. This yields a general method for four-bar path generation that is applicable to both closed and open paths.
Response Measurement Accuracy for Off-Resonance Excitation in Atomic Force Microscopy
Authors: Dick Andrew J. , Eason R. Parker
Published: March 2011

Dynamic atomic force microscopy (AFM) is an invaluable tool for characterizing and interacting with micro- and nano-scale systems. Standard measurement methods use a laser beam and a segmented photodiode to monitor the probe’s response. The diode reading is proportional to the slope of the probe and the displacement is obtained indirectly. As most operation methods use excitation around the fundamental frequency, calibration methods for determining the conversion factor to calculate the probe’s displacement are strongly inspired by the first vibrational mode shape. Within this paper, the results of an analytical study to predict measurement accuracy under non-standard excitation conditions with this calibration are presented. The influence of the excitation frequency, damping level, and laser spot location on this accuracy is investigated. The measurement accuracy for excitation at 2.5 times the fundamental frequency is of particular interest to the authors. Based upon the results, the use of a correction factor or a frequency-specific calibration is recommended.
Function-Based Analysis and Redesign of a Flyable Electromechanical Actuator Test Stand
Authors: Koopmans Michael T. , Tumer Irem Y.
Published: March 2011

Critical faults prevent electromechanical actuators (EMAs) from controlling primary flight surfaces aboard commercial and military human air/spacecraft. However, the efficiency and simplicity of the EMAs makes them appealing for use. For successful implementation, diagnostic and prognostic techniques identifying these critical faults must be optimized. This paper builds the foundation for the design of a second-generation test stand whose aim is to inject known EMA faults and record the data output while onboard an aircraft. First, an overview of faults is presented. Next, functional modeling is introduced as an effective system level representation to implement early design changes. Specifically, functional modeling is proposed to isolate functions of the test stand that can affect faulted and nominal actuator data collection through violations of post-processing statistical assumptions. The data collected from the EMA test stand will be used for actuator prognostic purposes and therefore must closely represent a full-scale actuator installation. This methodology will increase experiment validity, verifiable conclusions made regarding actuator remaining useful life, and overall system reliability.
Modeling and Analysis of an Optically-Actuated, Bistable MEMS Device
Authors: Kumar Vijay , Rhoads Jeffrey F.
Published: March 2011

Bistable microsystems have drawn considerable interest from the MEMS/NEMS research community not only due to their broad applicability in commercial applications, such as switching, but also because of the rich dynamic behavior they commonly exhibit. While a number of prior investigations have studied the dynamics of bistable microsystems, comparatively few works have sought to characterize their transient behavior. The present effort seeks to address this through the modeling and analysis of an optically-actuated, bistable MEMS switch. The work begins with the development of a distributed-parameter representation for the system, which is subsequently reduced to a lumped-mass analog and analyzed through the use of numerical simulation. The influence of various system and excitation parameters, including the applied axial load and optical actuation profile, on the system’s transient response is then investigated. Ultimately, the methodologies and results presented herein should provide for a refined predictive design capability for optically-actuated, bistable MEMS devices.
AIERO: An Algorithm for Identifying Engineering Relationships in Ontologies
Authors: Witherell Paul , Krishnamurty Sundar , Grosse Ian , Wileden Jack
Published: March 2011

This paper introduces the development and application of semantic relatedness techniques towards improved knowledge management in product development processes through ontologies. As part of this work, several different semantic relatedness techniques are reviewed, including a meronomic technique recently introduced by the authors. An aggregate semantic relatedness measure, dubbed AIERO, is introduced to quantify underlying relationships between aspects of the product development process. To assess its applicability and accuracy, AIERO is tested using three separate, independently developed ontologies. The results indicate AIERO is capable of identifying and measuring relationships across a knowledge framework and can consistently produce results one would intuitively expect. Finally, a case study is presented to evaluate AIERO’s effectiveness in exposing underlying causal relationships across a product development platform. The results of this case study suggest that AIERO can uniquely quantify semantic relatedness between concepts, effectively enabling design engineers to systematically narrow the scope where causal relationships may exist between various domain concepts in the product development processes.
Model-Based Optimal Control for Underwater Robotics
Authors: Ji Yingfeng , Amano Ryoichi S. , Perez Ronald A.
Published: March 2011

It is always one of the most challenging problems to control an underwater robotics due to the complex external forces in an underwater environment. It is difficult to obtain an ideal control performance using linear control technologies due to highly nonlinear properties of system. A valid method of linearization for nonlinear system is provided in this study. Based on this linearized system, the linear control theories were therefore employed for the tracking control of underwater robotics. The panning and tilting motions of this underwater robotics can basically track two given sinusoidal references based on the simulation results. In order to achieve a high-speed manipulation of this underwater robotics, fluid forces have to be considered and modeled. A computational fluid dynamics (CFD) technology is adopted in order to obtain more precise hydrodynamic models for simulation at the design stage. Two torque models that represent the degree of freedoms (DOFs) of panning and tilting respectively have been developed using the CFD software. The dynamic model of this robotics used in this paper is the one by Ji, et al [1].
Simultaneous Development of Design and Production Through Virtual Work Teams: The Plaster House Game
Authors: Bernardes Mauri´cio M. S. , de Jacques Jocelise Jacques
Published: March 2011

Problems in the process of product development often have roots in project management-related issues, such as communication flow, teamwork or even lack of knowledge about how to implement a simultaneous project. Hands-on activities based on real-world situations can be used to improve the learning process and train the abilities of future project managers, designers and producers, while stimulating participants to reflect on and discuss the group’s actions. This article describes an application of an activity referred to as the Plaster House Game. In this activity, students are organized in groups containing teams of designers and producers, which are located in separate rooms, with the goal of designing and building a miniature plaster house with provided components, using only online communication between teams and dealing with scheduling and production constraints set by the instructors. The work demonstrates that the use of simulation games can reinforce the learning process and allow students to rapidly identify potential problems that may occur in professional practice. It is also possible to show that the strategy chosen for project implementation, combined with better organization of work, can have a significant effect on the results of the exercise.
Kinematic Convexity of Rigid Body Displacements
Authors: Purwar Anurag , Ge Jeff
Published: March 2011

In this paper, we explore the notion of kinematic convexity for rigid body displacements. Previously, we have shown that when spatial rigid body displacements are represented by dual quaternions, an oriented projective space is better suited for the image space of displacements. Geometric algorithms for rigid body motions become more general and elegant when developed from the perspective of oriented projective geometry. By extending the concept of convexity in affine geometry to oriented projective geometry of the image space of rigid body displacements, we define the concept of kinematic convexity. This concept, apart from being theoretically significant, facilitates localization of a displacements and provides a measure of the kinematic separation useful in collision prediction, interference checking, and geometric analysis of swept volumes.
Application of Meshless Integral Method to Metal Forming
Authors: Ma Jianfeng , Summers Joshua David , Joseph Paul F.
Published: March 2011

In this paper, the meshless integral method based on the regularized boundary integral equation [1] is applied to analyze the metal forming processes characteristic with large deformation. Using Green-Naghdi’s theory, the updated Lagrangian governing integral equation is obtained from the weak form of elastoplasticity over a local sub-domain. The meshless function approximation is implemented by using the moving least-squares approximation. In Green-Naghdi’s theory, the Green-Lagrange strain is decomposed into the elastic part and plastic part and a J2 elastoplastic constitutive relation is used to relate the Green-Lagrange strain to the second Piola-Kirchhoff stress. The essential boundary conditions are imposed by a generalized collocation method and the natural boundary conditions are incorporated into the system governing equation and require no special handling. The solution algorithm for large deformation analysis is discussed in detail. Numerical examples show that this method is accurate and robust.
Concept Opportunity Diagrams: A Visual Modeling Method to Find Multifunctional Design Concepts
Authors: Kuhr Rachel , Wood Kristin , Jensen Dan , Crawford Richard
Published: March 2011

A transforming product is a system that has different functionality when physically changed or reconfigured into a different state. This increased functionality allows diverse customer needs to be met in a single product. Transforming devices have become more prevalent in recent years, as customers desire both increased capabilities and reduced complexity to reduce waste in our society. When designing a multifunctional product that transforms from one state to another, it can be difficult to conceptualize a design that does not reduce effectiveness or provide a compromise in either state. Transformational Design Theory has been developed and shows basic principles and facilitators that enable transformation to occur within a product space. An illustrative example is a chair designed to flip over to be used as a table. Flip is one of the 19 facilitators that are found in transformation design. This is also an example of expose/cover, a transformation design principle. Certain principles and facilitators are more prevalent than others in different design domains (such as tools, storage, organisms etc.). If we know the states that exist within the transformer, concept opportunity diagrams can be used to determine the opportunities for transformation within each state. When the diagrams are paired with a constituent relationship chart specific to each domain, new design concepts may be facilitated. This technique creates a cognitive process for designers where they process a series of questions when creating the concept opportunity diagram. The diagram will help them understand the unanticipated additional design space of each state. The Constituent Relationship Chart is a tool that allows them to apply their knowledge of these states to the facilitator hierarchy so that prospective facilitators can directly contribute to originally unforeseen design concepts. This paper presents this twofold process known as the Transformer Diagram Matching Method and shows the results on a fully functioning prototype of an office supply transformer. Although the proposed process is detailed, it allows the designer to find a large number of quality concepts they would not have foreseen otherwise. Our original concept generation processes produced thirty eight ideas, but this process added another thirty two ideas to the design space. The paper indicates specifically how this method can be integrated in with the standard transformational design process as well as suggests strategies for implementation within other design techniques.
Meshless Integral Method for Analysis of Elastoplastic Geotechnical Materials
Authors: Ma Jianfeng , Summers Joshua David , Joseph Paul F.
Published: March 2011

The meshless integral method based on regularized boundary equation [1][2] is extended to analyze elastoplastic geotechnical materials. In this formulation, the problem domain is clouded with a node set using automatic node generation. The sub-domain and the support domain related to each node are also generated automatically using algorithms developed for this purpose. The governing integral equation is obtained from the weak form of elastoplasticity over a local sub-domain and the moving least-squares approximation is employed for meshless function approximation. The geotechnical materials are described by pressure-sensitive multi-surface Drucker-Prager/Cap plasticity constitutive law with hardening. A generalized collocation method is used to impose the essential boundary conditions and natural boundary conditions are incorporated in the system governing equations. A comparison of the meshless results with the FEM results shows that the meshless integral method is accurate and robust enough to solve geotechnical materials.
3D Fractals From Periodic Surfaces
Authors: Wang Yan
Published: March 2011

Fractals are ubiquitous as in natural objects and have been applied in designing porous structures such as micro antenna and porous silicon. The seemingly complex and irregular structures can be generated based on simple principles. In this paper, we present three approaches to construct 3D fractal geometries using a recently proposed periodic surface model. By applying iterated function systems to the implicit surface model in the Euclidean or parameter space, 3D fractals can be constructed efficiently. Porosity is also proposed as a metric in fractal design.
Study of the Flow Over Wind Turbine Blade
Authors: Amano R. S. , Malloy R. J.
Published: March 2011

Recently there has been an increase in the demand for the utilization of clean renewable energy sources. This is a direct result of the volatility in oil prices and an increased awareness of human induced climate change. Wind energy has been shown to be one of the most promising sources of renewable energy. With current technology, the low cost of wind energy is competitive with more conventional sources of energy such as coal. Most blades available for commercial grade wind turbines incorporate a straight span-wise profile and airfoil shaped cross sections. These blades are found to be very efficient at lower wind speeds in comparison to the potential energy that can be extracted. However as the oncoming wind speed increases the efficiency of the blades decreases as they approach a stall point. This paper explores the possibility of increasing the efficiency of the blades at higher wind speeds while maintaining efficiency at the lower wind speeds. The design intends to maintain efficiency at lower wind speeds by selecting the appropriate orientation and size of the airfoil cross sections based on a low oncoming wind speed and given constant rotation rate. The blades will be made more efficient at higher wind speeds by implementing a swept blade profile. The torque generated from a blade using only the first optimization technique is compared to that generated from a blade using both techniques as well as that generated by NTK500/41 turbine using LM19.1 blades. Performance will be investigated using the computational fluid dynamics (CFD).
On Evaluation of Adaptive Mask Overlay Topology Synthesis Method Using Different Mask Shapes
Authors: Sharma Pranay , Saxena Anupam
Published: March 2011

Previous versions of the Material Mask Overlay Strategy (MMOS) for topology synthesis have primarily employed circular masks to simulate voids within the design region. MMOS operates on the photolithographic principle by appropriately positioning and sizing a group of negative masks to create voids within the design region and thus iteratively improve the material layout to meet the desired objective. The fundamental notion has been that a group of circular masks can represent a local void of any shape. Thus, circular masks, as opposed to those modeled using simple, non-intersecting, closed curves of generic shapes, have been employed. This paper investigates whether employing masks of more general shapes (e.g., any two-dimensional polygon) offers significant enhancements in efficiently attaining the appropriate topological features in a continuum. Here, performance of two other mask shapes, namely, elliptical and rectangular are compared with that of the circular masks. For fair comparison, two mean compliance minimization examples under resource constraints are solved as each design space is known to contain a unique minimum.
Participant Observations and Recommendations From an Integrated Design Project in Architecture and Engineering
Authors: Hartung Josh , McCormack Jay , Stefanic Cam , Cyr Jason , Bickford Keith , Winterbottom Bryce , Jacobus Frank
Published: March 2011

An interdisciplinary design project was conducted with students in the mechanical engineering and architecture departments at the University of Idaho. In order to offer the multidisciplinary design experience within the available bandwidth of instructors, the project was structured around and integrated into existing courses and resources. Past interdisciplinary product design courses have shown the value of interdisciplinary work in the professional development of students in addition to being effective at developing innovative new products. Descriptions of these courses provide insights on conducting them with regards to team structure, course structure, design process, and other topics. This paper summarizes observations reported from students and instructors involved in this project. Observations highlight challenges in project management, examples of cultural differences between disciplines, approaches to design, specifics of project ownership, and perceptions of level of detail in work products. Based on those observations, recommendations are made to develop and deploy a design process that facilitates the strengths of both disciplines and enables mentor guided project management. In addition, these recommendations will help establish a team culture and work setting that does not violate the culture of either discipline while enabling joint decision making, and address directly the impacts of a domain biased product as the design project focus.
On an Adaptive Mask Overlay Topology Synthesis Method
Authors: Saxena Anupam
Published: March 2011

A stochastic topology design approach is presented that yields binary, well connected continua. Inspired by the well known photolithographic technique used in the fabrication of micro-components, a number of negative-masks are appropriately laid over the design region to simulate voids. A unique feature is the effective use of the masks. In addition to their position and sizes, the number of circular masks is adaptively determined in each step of the optimization process. Thus, not only the void shapes but also their number is varied. The proposed method is significantly efficient compared to the previous implementations [21] and [23] and requires much less computational effort to yield good solutions. The honeycomb parameterization employed eliminates all subregion connectivity anomalies by ensuring edge connectivity throughout. Boundary smoothening is performed as a preprocessing step to moderate the notches, and to obtain an honest evaluation of a candidate design. Thus, both material and contour boundary interpretation steps are no longer required when post-processing the synthesized solutions. Various features of the method are demonstrated through the synthesis examples of small deformation compliant mechanisms.
Automatic Extraction of Conceptual Maps From Design Team Documents
Authors: Oberoi Sharad , Nguyen Dong , Finger Susan , Rose´ Carolyn Penstein
Published: March 2011

Most engineering project classes expect teams of students to collaborate and to build on existing knowledge to accomplish their project goals. As the project evolves, the team is expected to develop a shared understanding. However, students often become overwhelmed by the amount of information available and lose sight of the big picture. Instructors may also find it difficult to keep track of individual and team activities and are often forced to evaluate the product instead of the learning process. This paper presents preliminary results from a tool that supports effective knowledge management for engineering design projects. This framework, called DesignWebs, automatically extracts conceptual maps from the team’s evolving set of documents and discussions about an engineering artifact. It uses Latent Dirichlet Allocation, hierarchical clustering, and other machine learning techniques to generate a navigable web-based graph. Both instructors and students can browse this graph interactively to explore the concepts embedded inside design team documents and the connections between them. An experiment performed on documents obtained from a project course shows the effectiveness of DesignWebs in synthesizing the design knowledge from multiple sources of information in engineering project teams.
Optimizing the Unrestricted Placement of Turbines of Differing Rotor Diameters in a Wind Farm for Maximum Power Generation
Authors: Chowdhury Souma , Messac Achille , Zhang Jie , Castillo Luciano , Lebron Jose
Published: March 2011

This paper presents a new method (the Unrestricted Wind Farm Layout Optimization (UWFLO)) of arranging turbines in a wind farm to achieve maximum farm efficiency. The powers generated by individual turbines in a wind farm are dependent on each other, due to velocity deficits created by the wake effect. A standard analytical wake model has been used to account for the mutual influences of the turbines in a wind farm. A variable induction factor, dependent on the approaching wind velocity, estimates the velocity deficit across each turbine. Optimization is performed using a constrained Particle Swarm Optimization (PSO) algorithm. The model is validated against experimental data from a wind tunnel experiment on a scaled down wind farm. Reasonable agreement between the model and experimental results is obtained. A preliminary wind farm cost analysis is also performed to explore the effect of using turbines with different rotor diameters on the total power generation. The use of differing rotor diameters is observed to play an important role in improving the overall efficiency of a wind farm.
Integrated Top Down Dynamic and Hybrid Life Cycle Analysis Based Sustainable Design Approaches for New Product Development
Authors: Ali-Qureshi Zulfiqar
Published: March 2011

Environment friendly design methodology is a valid trade-off between the degrees of freedom and the sustainable solution. Life Cycle Assessment (LCA) is a powerful tool to calculate the environmental impact from the product and the manufacturing systems from cradle to grave including the consumption of all types of the resources. However, complexity of the LCA restricts its usefulness in the current state-of-the-art product and process system development. Most often, companies ignore to adopt a top-down approach and make a post manufacturing environmental audit. In fast-paced new product design process, the longevity of the product and the process development time has been reduced to its lowest level. Therefore, it has become rather difficult to meet the increasing competition of involving change, quicker response to the market as there exists a rapid change in the market economy. Infact the broader design principles suggests to create a product with sole functions and the architecture with no waste or refuse of recycling or refuse of incinerators to go in to grave of the land fill. Therefore, the preliminary design stages are simple and a bottom-up approach for the environmentally-conscience design is insufficient. Thus, the proposal is to make more functionally-oriented set of specific principles to not only directly satisfy the regulations but also provide design valuable attribute. In this context, an integrated top down dynamic & hybrid life cycle analysis-based design approach is presented to address above-mentioned issues with the company policy perspective and to satisfy the regulations and national/international standards in the wake of emerging localization paradigm in manufacturing system.
A Petri Net Based Interactive Manager Model for Virtual Maintenance Environment Application
Authors: Peng Gaoliang , Liu Wenjian , Liu Xinhua , Li Xin
Published: March 2011

Interaction is one of the most important characteristic of VR system. In this paper, a kind of Hierarchical Timed Color Petri Net (HTCPN) is defined and an Interactive Manager Model (IMM) of Virtual Maintenance Environment (VME) is established based on HTCPN. With the inputs including operation data from dataglove, collision information between objects and recognized assembly relationship, the IMM output concrete operation event to realize the interactive actions in VME such as navigation, dragging, assembling and disassembling. The practice test illustrate that IMM satisfied the requirements of VME such as real-time and incurrent, as well as realized the treatment of numerous discrete events and the capture of operation intend during virtual maintenance operation.
Parameter Identification of a Friction Model for Robotic Joints
Authors: Vakil Mohammad , Fotouhi Reza , Nikiforuk Peter N.
Published: March 2011

In this paper a new identification method to obtain the friction parameters in the joints of robotic manipulators is presented. These parameters are coulomb friction, static friction, Stribeck velocity constant and viscous damping coefficient. The available methods to find these parameters either require the design of a controller or the precise value of system parameters such as mass moment of inertia. In contrast, the new method proposed here finds these parameters by a nonlinear optimization approach which requires neither any knowledge of system’s parameters nor any controller design. The corresponding nonlinear optimization problem is solved using an efficient technique which does not require iteration or any initial estimate of optimization parameters. The new method proposed in this paper was experimentally verified on a robotic manipulator available in the robotics laboratory at the University of Saskatchewan.
Dynamic Maintenance Strategy With Q-Learning for Workstations in a Flow Line Manufacturing System
Authors: Kamarthi Sagar , Zeid Abe , Ozbek Yusuf
Published: March 2011

Every machine or equipment in a manufacturing facility is subject to failure due to deterioration based on cumulative wear, crack growth, erosion, etc. This failure will cause production losses and delays resulting in high costs. As the modern manufacturing systems are getting more and more complex, intelligent maintenance schemes must replace the old labor intensive planned maintenance systems to ensure that equipment continues to function. If the maintenance decision is based on the state of the system rather than its age, this leads to the choice of a Condition Based Maintenance (CBM) policy to prevent catastrophic unexpected machine breakdowns and increase the availability of individual machines, but it also introduces randomness into the manufacturing operation. This paper presents a Q-Learning model to dynamically group maintenance actions on different machines and execute them simultaneously, so that one can reduce maintenance cost and increase the efficiency of the manufacturing system.
The Least-Squares Galerkin Split Finite Element Method for Buoyancy-Driven Flow
Authors: Kumar Rajeev , Dennis Brian H.
Published: March 2011

The least-squares finite element method (LSFEM), based on minimizing the l2-norm of the residual is now well established as a proper approach to deal with the convection dominated fluid dynamic equations. The least-squares finite element method has a number of attractive characteristics such as the lack of an inf-sup condition and the resulting symmetric positive system of algebraic equations unlike Galerkin finite element method (GFEM). However, the higher continuity requirements for second-order terms in the governing equations force the introduction of additional unknowns through the use of an equivalent first-order system of equations or the use of C1 continuous basis functions. These additional unknowns lead to increased memory and computational requirements that have limited the application of LSFEM to large-scale practical problems. A novel finite element method is proposed that employs a least-squares method for first-order derivatives and a Galerkin method for second order derivatives, thereby avoiding the need for additional unknowns required by a pure LSFEM approach. When the unsteady form of the governing equations is used, a streamline upwinding term is introduced naturally by the least-squares method. Resulting system matrix is always symmetric and positive definite and can be solved by iterative solvers like pre-conditioned conjugate gradient method. The method is stable for convection-dominated flows and allows for equal-order basis functions for both pressure and velocity. The method has been successfully applied here to solve complex buoyancy-driven flow with Boussinesq approximation in a square cavity with differentially heated vertical walls using low-order C0 continuous elements.
In-Situ Monitoring and Prediction of Progressive Joint Wear Using Bayesian Statistics
Authors: An Dawn , Kim Nam Ho , Choi Jooho
Published: March 2011

In this paper, a statistical methodology of estimating wear coefficient and predicting wear volume in a revolute joint using in-situ measurement data is presented. An instrumented slider-crank mechanism is built, which can measure the joint force and the relative motion between the pin and bushing during operation. The former is measured using a load cell built onto a necked portion of the hollow steel pin, while the latter is measured using a capacitance probe. In order to isolate the effect of friction in other joints, a porous carbon air bearing for the revolute joint between the follower link and the slide stage, as well as a prismatic joint for the linear slide, are used. Based on the relative motion between the centers of pin and bushing, the wear volumes are estimated at six different operating cycles. The Bayesian inference technique is used to update the distribution of wear coefficient, which incorporates in-situ measurement data to obtain the posterior distribution. In order to obtain the posterior distribution, Markov Chain Monte Carlo technique is employed, which effectively draws samples of the given distribution. The results show that it is possible to narrow the distribution of wear coefficient and to predict the future wear volume with reasonable confidences. The effect of prior distribution on the wear coefficient is discussed by comparing with non-informative case.
A Study on the Formability of IF and Plain Carbon Mild Steels
Authors: Nourani Mohamadreza , Aliverdilu Hossein , Monajati Zadeh Hossein , Khorsand Hamid , Shokuhfar Ali , Milani Abbas S.
Published: March 2011

Steel sheet metals are widely used in different industries due to their high strength, good weldability, availability, moderate cost, and the ability to form to complex 3D parts. The study of the formability of sheet metals is often done by means of Forming Limit Diagram (FLD) which presents the major and minor engineering strain thresholds under different deformation states. In this article, the formability parameters of three different steel sheet metals with the same thickness have been determined by uniaxial tension test and their FLDs have been produced by Hecker method: RRSt14O3, Zinc coated IF (Interstitial Free) steel and uncoated IF steel. Also the materials’ formability during the stamping process of a car door inner panel has been investigated as a case study to substitute the original design of raw material, coated IF steel, with a cheaper alternative. Among the tested materials to form the part, the uniaxial tension results showed that the formability parameters of uncoated IF steel was higher than the coated IF steel and the parameters of RRSt14O3 sheet metal was the lowest. The FLD of coated IF steel sheet was the highest (best formability). Differences among the formability parameters in uniaxial tension, the FLDs, and the stamping behavior of the part with different steel sheet metals have been explained by their surface roughnesses and the friction coefficients that affect the material flow during the FLD test as well as the stamping process.