bluuebunny/crossref_metadata_2025 huggingface dataset:
On Line Screw Systems and Their Application to Flexure Synthesis
Authors: Su Hai-Jun , Tari Hafez
Published: March 2011

This paper presents a new screw theory that deals with “lines” and “line systems”. A line is a screw with a zero pitch. A rank m screw system is called a line screw system if it contains m linearly independent lines. The set of lines within a screw system is called the line variety. A general m-system is a line screw system if the rank of its line variety equals m. This paper will answer two questions: (1) how to calculate the rank of the line variety for a given m-system and (2) how to algorithmically find a set of linearly independent lines from the given screw system. The motivation of this work comes from flexure synthesis whose goal is to find a pattern of flexures to achieve a specified motion. It has been previously found that a wire flexure is considered a line screw, or more specifically a pure force wrench. The synthesis of flexures is to remove undesired motion by applying constraints with flexures. By following reciprocity and definitions of line screws, we have derived the sufficient and necessary conditions of line screw systems. When applied to flexure synthesis, we show that not all motion pattern can be realized with wire flexures connected in parallel. A computational algorithm based on the line screw theory is developed to find all admissible line screws or force wrenches for a given motion space. At last two flexure synthesis case studies are provided to demonstrate the theory and the algorithm.
Hybrid Power/Energy Generation System Design Through Multistage Design Optimization Problem With Complementarity Constraints
Authors: Lu Shen , Schroeder Nathan B. , Kim Harrison M.
Published: March 2011

The optimal design of hybrid power generation systems (HPGS) can significantly improve the economical and technical performance of power supply. However, the discrete-time simulation with logical disjunctions involved in HPGS design usually leads to a nonsmooth optimization model, to which well established techniques for smooth nonlinear optimization could not be directly applied. This paper proposes a multistage design optimization problem with complementarity constraints approach for HPGS design, which introduces a complementarity formulation of the nonsmooth logical disjunction, as well as a multistage decomposition framework, to ensure a fast local solution. A numerical study of a stand-alone hybrid photovoltaic (PV)/wind power generation system is presented to demonstrate the effectiveness of the proposed approach.
Trending Mining for Predictive Product Design
Authors: Tucker Conrad S. , Kim Harrison M.
Published: March 2011

The Preference Trend Mining (PTM) algorithm that we propose in this work aims to address some fundamental challenges of current demand modeling techniques being employed in the product design community. The first contribution is a multistage predictive modeling approach that captures changes in consumer preferences (as they relate to product design) over time, hereby enabling design engineers to anticipate next generation product features before they become mainstream/unimportant. Because consumer preferences may exhibit monotonically increasing or decreasing, seasonal or unobservable trends, we proposed employing a statistical trend detection technique to help detect time series attribute patterns. A time series exponential smoothing technique is then used to forecast future attribute trend patterns and generate a demand model that reflects emerging product preferences over time. The second contribution of this work is a novel classification scheme for attributes that have low predictive power and hence may be omitted from a predictive model. We propose classifying such attributes as either obsolete, nonstandard or standard, with the appropriate classification given based on the time series entropy values that an attribute exhibits. By modeling attribute irrelevance, design engineers can determine when to retire certain product features (deemed obsolete) or incorporate others into the actual product architecture (standard) while developing modules for those attributes exhibiting inconsistent patterns throughout time (nonstandard). A cell phone example containing 12 time stamped data sets (January 2009-December 2009) is used to validate the proposed Preference Trend Mining model and compare it to traditional demand modeling techniques for predictive accuracy and ease of model generation.
Trajectory Planning and Impact Reduction in Wire-Actuated Parallel Manipulators With Elastic Wires
Authors: Agahi Maryam , Notash Leila
Published: March 2011

In the work presented, the optimal trajectory planning in wire-actuated parallel manipulators in the presence of an obstacle is investigated. The kinematics and dynamics of a wire-actuated parallel manipulator considering the elasticity and damping effects of wires are described. The redundancy resolution of planar wire-actuated parallel manipulators is investigated at the torque level in order to perform desirable tasks to minimize the effect of impact, while maintaining positive tension in each wire. A local optimization routine is used in the simulation to minimize the tension in the wires while modifying the trajectory of the mobile platform and maintaining positive wire tensions. During collision, the tension in the wires is optimized to reduce the effect of impact, and after collision, the trajectory is modified and the wire tensions are minimized in order to avoid collision for the remainder of the trajectory. The effectiveness of the presented approach is studied through a simulation of an example planar wire-actuated manipulator.
Design and Analysis of Hybrid Guideway Heating System for Morgantown Personal Rapid Transit
Authors: Vedam Anand , Sneckenberger John E.
Published: March 2011

The Morgantown Personal Rapid Transit (M-PRT) system is a comfortable conveyance for travel in Morgantown, WV. One of its operating concerns is the increasing cost of heat to the guideway during winter. As the vehicles cannot run safely during snow, the system includes a guideway heating system to melt the ice from the guideway. To reduce the use of expensive natural gas, an interest has been expressed to define a hybrid heating system using an alternate fuel supply. Solid Oxide Fuel Cell (SOFC) was incorporated in the hybrid heating system. This hybrid heating system was designed, and then a detailed analysis was performed to ascertain the performance parameters like heat produced, thermal efficiency, cost of the system and the emissions involved. This high temperature fuel cell releases large amounts of usable heat in the form of exhaust gases. The exhaust gases are deprived of any undesired emissions that pollute the atmosphere. A USDOE EPSCoR WV State Implementation Award conducted by Advance Power Electricity Research Center (APERC) at West Virginia University provided support for conducting this research.
Displacement and Blocking Force Performance of Piezoelectric T-Beam Actuators
Authors: Kommepalli Hareesh K. R. , Mateti Kiron , Rahn Christopher D. , Tadigadapa Srinivas A.
Published: March 2011

In this paper, we present the experimental validation of the detailed models developed for the flexural motion of piezoelectric T-beam actuators. With a T-shaped cross-section, and bottom and top flange and web electrodes, a cantilevered beam can bend in both in-plane and out-of-plane directions upon actuation. Analytical models predict the tip displacement and blocking force in both directions. Mechanical dicing and flange electrode deposition was used to fabricate six meso-scale T-beam prototypes. The T-beams were experimentally tested for in-plane and out-of-plane displacements, and out-of-plane blocking force. The analytical models closely predict the T-beam displacement and blocking force performance. A nondimensional analytical model predict that all T-beam designs for both in-plane and out-of-plane actuation, regardless of scale, have nondimensional displacement and blocking force equal to nondimensional voltage. The results from experiments are favorably compared with this theoretical prediction.
Online Robot Simulation for Collaborative Engineering and Education
Authors: Seow Chi Min , Nelson Carl A.
Published: March 2011

This paper presents an online robot simulation tool built using X3D, extensible 3D graphics that can be used as either an educational or design tool. A literature review of some current web-based learning tools is outlined in the context of mechanisms and robotics. Also, different web technologies that were tested in the process of building the simulation tool are discussed, along with a technical review of current desktop sharing software available online. Lastly, an example of a virtual robot is presented with the technical design information explained in detail. Enhanced by a robust user interface, the simulation environment is intuitive for users with limited mechanical design background. A powerful “back-end” computational engine is envisioned to allow for various interactive features in simulations to be accomplished.
Optimization of Asymmetric Damper Parameters of an Automotive Suspension for Minimal Camber Angle Variations
Authors: Balike Krishna Prasad , Rakheja Subhash , Stiharu Ion
Published: March 2011

Asymmetric dampers invariably employed in automotive suspensions are known to cause ‘damper jacking’. The influence of the damper jacking on the suspension kinematic responses, particularly variations in the camber angle, are generally ignored while synthesizing a damper. This study presents influences of damper asymmetry on the camber angle variations of a double wishbone type of suspension together with the dynamic responses under measured urban road inputs. Simulation studies employing a kineto-dynamic quarter-car model comprising a bilinear damper revealed increase in the camber angle variations with an increase in the damper asymmetry, while this increment showed nonlinear relation with the suspension deflection. This study further investigates synthesis of an optimal two-stage asymmetric damper to yield a compromise between the conflicting performance measures. A composite performance index comprising the ride comfort and road holding measures with limit constraint on camber angle variation is formulated to seek optimal damper parameters. The results are presented so as to yield design guidance for synthesis of asymmetric dampers.
Fundamental Concepts for Collaboratively Obtaining Optimum Product Designs
Authors: Yoshimura Masataka
Published: March 2011

Fundamental concepts for obtaining optimum product designs from higher view points are presented. These fundamental concepts are: (1) concepts that aim to achieve designs that are in harmony with natural and human environments; (2) collaborations based on mutuality, where the collaborating individuals are free from inhibiting hierarchies; and (3) methodologies that enable discovery of effective solutions by examining the deepest, most fundamental levels of design problems. Product designs that minimize stress on natural environments and maximize benefit to people are increasingly important, given limited natural resources and an increasing world population. The achievement of such product designs generally requires collaborative scenarios based on mutuality and equality of the participants, and the implementation of characteristics-based hierarchical optimization methodologies. Practical methodologies based on these fundamental concepts are discussed here and examples are provided.
Recyclability Oriented Lifecycle Design of Mechatronic Products
Authors: Coulibaly Amadou , Gardoni Mickae¨l , Gaye Khalifa , Huang Ying
Published: March 2011

The mechatronic systems are manufactured and high technology integrated products consisting of mechanical components, electronic devices and software modules. Such products are present in a very fast growing number of industrial products like mobile phones, digital cameras, high standing automobiles, aeronautics or NC machines. Some of these products are mass consumption items such as mobile phones that are characterized by a relatively short commercial lifetime. And then these products are renewed after a few months. Dealing with all this growing amount of wastes generated, is a crucial environmental problem that is becoming a worrying situation. This article proposes an approach aimed to lifecycle design for the recyclability of mass consumption mechatronic products. In this paper, we firstly describe and analyze the mechatronic products behavior from reliability and recyclability viewpoints. Then, we propose an approach for designing such products in order to fulfill recyclability requirements by using a knowledge-based design adviser module.
Real-Time Vibration Suppression and Composite Adaptive Control of Coordinated Motion for Space Flexible Manipulator
Authors: Hong Zhaobin , Li Chen
Published: March 2011

The real-time vibration suppression and composite adaptive control of coordinated motion for space flexible manipulator with an attitude-controlled base are studied. The dynamic equations of the system are developed by using the Lagrangian assumed modes methods. It is verified that the dynamic equation and Jacobi matrix of the system can be linearly dependent on a group of inertial parameters. Based on the results and with the augmentation approach, a composite adaptive control of space flexible manipulator to track the desired trajectory is developed. Considering the dynamics of flexible subsystem, a control scheme is presented to suppress the vibration during the real-time operation. In particular, it doesn’t require measuring the position, velocity nor acceleration of the base because of an effective exploitation of the particular property of the system dynamics. The numerical simulation is carried out, which confirms the controller proposed is feasible and effective.
Achieving Multistability Through Use of a Single Bistable Compliant Mechanism
Authors: Chen Guimin , Gou Yanjie , Zhang Aimei
Published: March 2011

A compliant multistable mechanism is capable of steadily staying at multiple distinct positions without power input. Many applications including switches, valves, relays, positioners, and reconfigurable robots may benefit from multistability. In this paper, two new approaches for synthesizing compliant multistable mechanisms are proposed, which enable designers to achieve multistability through the use of a single bistable mechanism. The synthesis approaches are described and illustrated by several design examples. Compound use of both approaches is also discussed. The design potential of the synthesis approaches is demonstrated by the successful operation of several instantiations of designs that exhibit three, four, five, and nine stable equilibrium positions, respectively. The synthesis approaches enable us to design a compliant mechanism with a desired number of stable positions.
Interactive Interface Design for Design Rationale Search and Retrieval
Authors: Liang Yan , Lu Wen Feng , Liu Ying , Johnson Lim Soon Chong
Published: March 2011

In the rapid product design and development, design rationale (DR) information is critical for designers to understand the design technology and for better knowledge reuse. The visualization of DR capture, search and retrieval systems is important in assisting designers to gain insights and benefits from the increasing DR repository, e.g. major design issues of an artifact and design alternatives to the issues. In literatures, we have observed that the current DR systems provide limited interactive guidance in helping designers to DR navigate and search. In our previous work, we have proposed an ISAL (Issue, Solution and Artifact Layer) model for DR discovery in which the DR information is mined from a large amount of archival documents using text mining techniques. In this paper, we focus on interactive user interface (UI) design for our DR retrieval system. With functions like view, search and analysis, designers are visually guided during DR searching. Using patents as our research data, the view functions enable engineering designers to intuitively navigate DR repository. Search functions support designers to retrieve relevant DR from multiple aspects and visualize the structure of relevant DRs from a holistic view. By applying analysis functions on the retrieved DR, visualization is able to suggest some useful DR insights, e.g. key components of certain issues, possible solutions of relevant issues, major issues of an artifact and technology development trend analysis, etc. Together with the function examples, we illustrate the merits of our interface design for DR search and retrieval.
Comparison of Natural Frequencies of Composite Cylindrical Shells: A Squared Lattice With Its Equivalent Seamless One
Authors: Kargarnovin M. H. , Jam J. E. , Hashemian A. H.
Published: March 2011

Modern Latticed composite materials whose high specific strength and stiffness are utilized in spacecraft and rocket structures to a sufficiently high extent are now widely used in primary airframe structures. In this work a comparison between squared latticed composite cylinder shells and the equivalent hollow cylinder with same weight, outer radius, length and material is done. An analytical equation is derived for natural frequency of square latticed composite shells. The first fifth modes are taken to be compared. The analytical and FEM results are shown and compared to each other. Also, as discussed, the squared lattice cylinder shell reaches to their natural frequencies easily than the equivalent hollow cylinder shell.
A Harmonic-Based Method for Computing the Stability of Periodic Oscillations of Non-Linear Structural Systems
Authors: Thomas O. , Lazarus A. , Touze´ C.
Published: March 2011

In this paper, we present a validation on a practical example of a harmonic-based numerical method to determine the local stability of periodic solutions of dynamical systems. Based on Floquet theory and Fourier series expansion (Hill method), we propose a simple strategy to sort the relevant physical eigenvalues among the expanded numerical spectrum of the linear periodic system governing the perturbed solution. By mixing the Harmonic Balance Method and Asymptotic Numerical Method continuation technique with the developed Hill method, we obtain a purely-frequency based continuation tool able to compute the stability of the continued periodic solutions in a reduced computation time. This procedure is validated by considering an externally forced string and computing the complete bifurcation diagram with the stability of the periodic solutions. The particular coupled regimes are exhibited and found in excellent agreement with results of the literature, allowing a method validation.
Complex Eigenvalue Analysis and Nonlinear Transient Vibration of an Axially Moving String With an Attached Travelling Oscillator Under Wind Excitations
Authors: Wang Yuefang , Lu¨ Lefeng , Huang Lihua
Published: March 2011

The eigenvalue analysis and nonlinear dynamics of an axially moving string with an attached traveling oscillator excited by wind loadings are presented in this paper. The couplings in both of mass and stiffness between the string and the oscillator are considered. The Green’s function in an explicit form is obtained by the theorem of Green’s function construction, and the analytical transcendental equation is directly obtained. The maximum variance rate is defined to analyze the coupling strength of the subsystems. It is demonstrated that the first eigenvalue changes significantly when the natural frequency of the oscillator is close to that of the string’s first frequency. The equation of motion of nonlinear transient vibration of the coupled system is obtained by considering aerodynamic loading and geometric nonlinearity of the string. The equation is solved numerically for the transient response of the vibration. The effect of the geometrical nonlinearity due to large deformation and the interaction between the oscillator and the string are also presented.
Design of an Immersive Peripheral for Object Grasping
Authors: Chardonnet Jean-Re´my , Le´on Jean-Claude
Published: March 2011

During product development processes, simulations involving user’s grasping operations are of increasing interest to incorporate more quantitative information in DFA (Design For Assembly) or immersive simulations. We present several prototypes of an immersive peripheral device for controlling a virtual hand with fine dexterity. These prototypes are derived from the analysis of a grasping action to define the structure and main features of this device. The prototypes, as easy to manipulate as a computer mouse, enable the simultaneous control of a large number of degrees of freedom (dofs). The design issues, where physical phenomena, physiological behavior and device structure are all tightly combined and significantly influence the overall interaction, are reviewed. These issues include the generation of dofs, monitoring kinematics, force reduction during virtual hand and finger movements, and the influence of device design, sensor types and their placement on the interaction and on the range of configurations that can be achieved for grasping tasks, dexterity, and performance. Examples of grasping tasks show the effect of these immersive devices to reach user-friendly and efficient interactions with objects bringing new insight to the interaction with virtual products.
A Three-DOF Rotational Parallel Manipulator Without Intersecting Axes
Authors: Chen Ziming , Liu Jingfang , Huang Zhen
Published: March 2011

It is difficult to manufacture parallel manipulators(PMs) with multiple revolute joint axes intersecting at one point. These types include the 3-DOF spherical parallel manipulators (SPMs), the 4-DOF 3R1T and 2R2T PMs, the 5-DOF 3R2T PMs. This problem makes it hard to achieve the expected mobility of these PMs. In this paper, a 3-RPS cubic PM is studied which has three rotational freedoms and no intersecting axes. The orientation workspace of this PM is analyzed. Some discussions about the differences between the traditional SPMs and this PM are proposed. The results show that the 3-RPS cubic PM can achieve three rotational motions and has no intersecting axes.
Active Dynamic Balancing Unit for Controlled Shaking Force and Shaking Moment Balancing
Authors: van der Wijk Volkert , Herder Just L.
Published: March 2011

For a mechanism with many elements that needs to be shaking-force and shaking-moment balanced with a low addition of mass, a low addition of inertia, and a low addition of complexity, the use of actively computer-controlled balancing elements is promising. With these actively controlled elements the net reaction forces and the net reaction moments to the base of the mechanism can be balanced directly instead of balancing each mechanism element separately as is common practice for passive balancing. Adaptability of the control also allows balancing of (variable) payload. This paper presents the concept of an active dynamic balancing unit, which is a unit that is mounted on unbalanced mechanisms and is controlled such that the combined system is dynamically balanced. The conceptual design and possible control strategies of such a unit, including pick-and-place motion of variable payloads, is studied. A simulation is presented to give insight in the possibilities and limitations of active dynamic balancing.
Four Novel Pick-and-Place Isoconstrained Manipulators and Their Inverse Kinematics
Authors: Lee Po-Chih , Lee Jyh-Jone , Lee Chung-Ching
Published: March 2011

The four-degree-of-freedom (4-DoF) Schoenflies-motion (briefly termed X-motion) manipulator with the fast pick-and-place operation is essential for industrial assembly and packaging. For the development of this kind of industrial manipulator, we provide architectures and inverse kinematics of four X-motion isoconstrained parallel mechanisms with two limbs, CuuUwHw-//-CvvUwHw, CuRuuUhw-//-CvRvvUhw, CuRuPHw-//-CvRvPHw and CuPuUhw-//-CvPvUhw (R, P, H and C denote revolute, prismatic, screw and cylindrical pairs respectively; U indicates a universal joint). These novel manipulators are excerpted from numerous general architectural types of isoconstrained parallel generators of X-motion. In this work, their architectures and mobility are first elucidated in detail. With the help of the well-known D-H symbolic notations, their three translational and one rotational motion are comprehensively verified through the four-by-four coordinate transformation matrix approach. Inverse kinematic solutions of joint displacements of each manipulator are further established by using the matrix algebra method for the reference of potential applications.
Rupture and Reformation of Ultra-Thin Surface Films
Authors: Chong William W. F. , Teodorescu Mircea , Rahnejat Homer
Published: March 2011

In lubricated contact conjunctions film ruptures close to the exit boundary. This significantly affects the load carrying capacity and can lead to direct surface interactions. Nano-scale films (several molecular diameters of the lubricant) are no exception, a fact that has been observed using ellipsometry studies for ultra-thin film conjunctions representative for high storage capacity hard disk drives. Immediately beyond the film rupture an area of cavitation occurs and the continuity of flow condition is breached. It has been shown that for molecularly smooth surfaces solvation effect becomes dominant. This means that the contact exit is subject to discrete drainage of lubricant and may be devoid of a sufficient lubricant for film reformation to occur. This can be a stumbling block in an increasing quest to increase the data storage density of hard disk drives. Wear can become a problem as well as non-uniformity of free surface film at the inlet meniscus. It has been noted that peaks of lubricant can gather in some places, a phenomenon referred to as lubricant mogul. These localized piles of lubricant can exceed the nominally aimed for lubricant film thickness necessary for a given data storage level. This paper carries out an in-depth prediction of ultra thin film lubricant behavior through the contact. Hydrodynamic as well as near surface effects and intermolecular interactions responsible for the supply, formation, cavitation and reformation of thin films in the slider-disk conjunction have been considered.
Effect of Microbeam Electrical Resistivity on Vibration Frequency Shift of an Electrostatically Actuated Microbeam
Authors: Pasharavesh Abdolreza , Ahmadian M. T. , Alizadeh Vaghasloo Y.
Published: March 2011

Nonlinear vibration of a microbeam actuated by a suddenly applied voltage with considering the effect of voltage distribution on the beam due to electrical resistivity of beam is investigated. Homotopy perturbation method is implemented to solve the coupled nonlinear partial differential equations of motion. The vibration frequency variation and damping at various resistivities is studied. Considering resistivity, effect of applied voltage and beam length on the frequency shift and damping ratio is analyzed. Findings indicate there exists a jump in frequency shift and damping ratio at a critical resistivity. Variation of critical resistivity with respect to modulus of elasticity and beam density is also studied. Results show the jump in frequency shift and damping ratio can be controlled with proper selection of modulus of elasticity and density of beam.
Validating Designs Through Sequential Simulation-Based Optimization
Authors: Li Jing , Mourelatos Zissimos P. , Kokkolaras Michael , Papalambros Panos Y. , Gorsich David J.
Published: March 2011

Computational simulation models support a rapid design process. Given model approximation and operating conditions uncertainty, designers must have confidence that the designs obtained using simulations will perform as expected. This paper presents a methodology for validating designs as they are generated during a simulation-based optimization process. Current practice focuses on validation of simulation models throughout the entire design space. In contrast, the proposed methodology requires validation only at design points generated during optimization. The goal of such validation is confidence in the resulting design rather than in the underlying simulation model. The proposed methodology is illustrated on a simple cantilever beam design subject to vibration.
2-D Path Planning for Direct Laser Deposition Process
Authors: Routhu Swathi , Kanakanala Divya , Ruan Jianzhong , Liu Xiaoqing Frank , Liou Frank
Published: March 2011

The zigzag and offset path have been the two most popular path patterns for tool movement in machining process. Different from the traditional machining processes, the quality of parts produced by the metal deposition process is much more dependent upon the choice of deposition paths. Due to the nature of the metal deposition processes, various tool path patterns not only change the efficiency but also affect the deposition height, a critical quality for metal deposition process. This paper presents the research conducted on calculating zigzag pattern to improve efficiency by minimizing the idle path. The deposition height is highly dependent on the laser scanning speed. The paper also discussed the deposition offset pattern calculation to reduce the height variation by adjusting the tool-path to achieve a constant scanning speed. The results show the improvement on both efficiency and height.
An Energy Approach to a 2DOF Compliant Parallel Mechanism With Self-Guiding Statically-Balanced Straight-Line Behavior
Authors: Rosenberg Emile J. , Radaelli Giuseppe , Herder Just L.
Published: March 2011

This paper presents a novel straight-line self-guiding statically-balanced mechanism which reflects on the advantages of lumped compliant mechanisms. The forthcoming structural design is conceived with an energy approach for static balancing of mechanisms. In this paper the application and effectiveness of the energy approach as a synthesis tool is validated. Moreover the paper demonstrates the translation from pseudo-rigid body model to lumped compliance in statically-balanced mechanisms. A physical prototype and a finite-element model served to evaluate the conceptual design. Manufacturing techniques are suggested for rapid, light-weight and cost-efficient prototyping. The presented self-guiding mechanism is statically-balanced along its straight-line range of motion while showing stable behavior in other directions.
Marker-Free Detection of Instruments in Laparoscopic Images to Control a Cameraman Robot
Authors: Amini Khoiy Keyvan , Mirbagheri Alireza , Farahmand Farzam , Bagheri Saeed
Published: March 2011

Assistant robots are widely used in laparoscopic surgery to facilitate the camera holding and manipulation task. A variety of a hands-free operator interfaces have been implemented for user control of the robots, including voice commands, foot pedals, and eye and head motion tracking systems. This paper proposes a novel user control interface, based on processing of the laparoscopic images, that enables the robot to automatically adjust the view of the laparoscopic camera without disturbing the surgeon’s concentration. An effective marker-free detection method was investigated to track the instrument position in the laparoscopic images in real time so that the robot could center the instrument tip in the camera view. Considering several available methods it was found that a color space analysis, based on the quantitative comparison of the background’s and instrument’s pixels color contexts, provides the best results. The color contexts were presented in covariance matrix and mean values and analyzed using Mahalanobis distance measure in RGB color space. Tests on laparoscopic images with controlled conditions, e.g., sufficient light and low noises, revealed 86 percent correct detection with a processing rate of 3.7 frames per second on a conventional PC. Further work is going on to improve the algorithm.
Simulation of Surface Chemistry in CVD Technologies: A Detailed Deposition Model With Surface Diffusion
Authors: Klimovich Sergei , Gorbachev Yuriy , Krzhizhanovskaya Valeria
Published: March 2011

Modern electronics relies on high quality semiconductor materials. For thin films used in solar cells and flat panel displays, the key issues are the precise composition and spatial uniformity. Modeling and simulation are indispensable for optimizing the technologies of semiconductor film production, such as chemical vapor deposition (CVD), plasma enhanced CVD and hot-wire CVD. Multiphysics simulations of electromagnetic dynamics coupled with the flow of reacting gases, plasma discharge and deposition processes, allowed us to optimize large-scale plasma chemical reactors [1] and to find other solutions to complex industrial applications [2,3].
Reducible Uncertain Interval Design (RUID) by Kriging Meta-Model Assisted Multi-Objective Optimization
Authors: Hamel J. M. , Azarm S.
Published: March 2011

Optimization under uncertainty can be a difficult and computationally expensive problem driven by the need to consider the degrading effects of system variations. Sources of uncertainty that may be reducible in some fashion present a particular challenge because designers must determine how much uncertainty to accept in the final design. Many of the existing approaches for design under input uncertainty require potentially unavailable or unknown information about the uncertainty in a system’s input parameters; such as probability distributions, nominal values or uncertain intervals. These requirements may force designers into arbitrary or even erroneous assumptions about a system’s input uncertainty when attempting to estimate nominal values and/or uncertain intervals for example. These types of assumptions can be especially degrading during the early stages in a design process when limited system information is available. In an effort to address these challenges a new design approach is presented that can produce optimal solutions in the form of upper and lower bounds (which specify uncertain intervals) for all input parameters to a system that possess reducible uncertainty. These solutions provide minimal variation in system objectives for a maximum allowed level of input uncertainty in a multi-objective sense and furthermore guarantee as close to deterministic Pareto optimal performance as possible with respect to the uncertain parameters. The function calls required by this approach are dramatically reduced through the use of a kriging meta-model assisted multi-objective optimization technique performed in two stages. The capabilities of the approach are demonstrated through three example problems of varying complexity.
A Conflict Detection Approach for Collaborative Management of Product Interfaces
Authors: Hisarciklilar Onur , Rahmani Keyvan , Thomson Vince
Published: March 2011

In complex products, maintaining subsystem consistency throughout the design process is often a time-consuming process of document exchange among cooperating functions. This paper describes a conflict management approach that lead to the computer-aided management of the product specification conflicts that happen due to the integration of subsystems. In order to define a framework, a systematic interface representation which proposes building generic interface schemes for subsystem connectivity representation is described. Based on this methodology, a functional architecture of the proposed conflict management method, along with generic exception taxonomy of conflicts is developed. The applicability of the proposed concepts is discussed through illustrative examples. The proposed methodology is intended to allow automatic detection and handling of interface connectivity errors throughout collaborative design processes.
A Review of Two Patents Relating to Novel Energy Harvesting Techniques to Provide Electrical Power On-Board Gun-Fired Projectiles
Authors: Rastegar Jahangir , Murray Richard
Published: March 2011

This is a review of two patents relating to electrical power generation on-board gun-fired munitions. The devices harvest mechanical energy from the motion of the projectile (e.g. the axial firing acceleration), and then convert the energy from mechanical to electrical using novel mechanisms and materials such as piezoelectric elements. The devices are particularly important for several reasons. Firstly, the devices are inherently safe because the root source of the electrical energy is the motion of the projectile; therefore no electrical energy can be produced until after the projectile is fired. Second, the devices have a much longer shelf-life than competing electrical power sources such as batteries. Finally, the devices are simple, rugged, and reliable making them ideal for the harsh environment on-board gun-fired projectiles. In addition to presenting the general approach, the logical framework of the patented embodiments is presented, especially with respect to the types of motion used for harvesting and the challenges presented by the varied magnitudes of those motions in different weapon platforms.
Polynomial-Chaos-Based Numerical Method for the LQR Problem With Uncertain Parameters in the Formulation
Authors: Blanchard Emmanuel , Sandu Corina , Sandu Adrian
Published: March 2011

This paper proposes a polynomial chaos based numerical method providing an optimal controller for the linear-quadratic regulator (LQR) problem when the parameters in the formulation are uncertain, i.e., a controller minimizing the mean value of the LQR cost function obtained for a certain distribution of the uncertainties which is assumed to be known. The LQR problem is written as an optimality problem using Lagrange multipliers in an extended form associated with the polynomial chaos framework, and an iterative algorithm converges to the optimal answer. The algorithm is applied to a simple example for which the answer is already known. Polynomial chaos based methods have the advantage of being computationally much more efficient than Monte Carlo simulations. The Linear-Quadratic Regulator controller is not very well adapted to robust design, and the optimal controller does not guarantee a minimum performance or even stability for the worst case scenario. Stability robustness and performance robustness in the presence of uncertainties are therefore not guaranteed. However, this is a first step aimed at designing more judicious controllers if combined with other techniques in the future. The next logical step would be to extend this numerical method to H2 and then H-infinity problems.
Criteria for the Static Balancing of Compliant Mechanisms
Authors: Gallego Juan A. , Herder Just L.
Published: March 2011

Compliant mechanisms achieve their mobility through the deformation of their members, this means that part of the energy transmitted from the input to the output of the mechanisms will be stored in the mechanisms as strain energy. This energy storage in some cases is not a desired characteristic and a way to solve this problem is by static balancing the behavior of the mechanisms. Here five criteria are presented that can be used in the static balancing of compliant mechanisms. The criteria are combined in a systematic way with design methods for compliant mechanisms as an exercise to find feasible combinations for the development of design methods for statically balanced compliant mechanisms. The feasibility of the combination between criteria and design methods for compliant mechanisms is demonstrated by using rigid body mechanisms with torsion springs, roughly emulating their compliant counterpart.
A Viscoelastic Based Mechanism for Improving Spring-In Angle Predictions in Compression Molded Thermoplastic Matrix Composites
Authors: Lynam Corey , Milani Abbas S.
Published: March 2011

In this paper, dimensional distortion during the compression molding of thermoplastic matrix composites, typically described as spring-in or spring forward, is investigated through a finite element model. Spring-in is the reduction of the enclosed angle of two surfaces on the final component shape with respect to the original mold shape. Spring-in of thermoplastic matrix composites has typically been attributed to the difference in the thermal expansion of in-plane and through thickness directions of the composite. However, using this mechanism alone during modeling has not shown complete agreement with the experimental data. A new meso-level mechanism based on the viscoelasticity effect of the thermoplastic matrix is proposed. With this mechanism, the predicted spring-in angle can be in good agreement with experiments.
Utilizing a Classification Scheme to Facilitate Rigid-Body Replacement for Compliant Mechanism Design
Authors: Olsen Brian M. , Issac Yanal , Howell Larry L. , Magleby Spencer P.
Published: March 2011

The knowledge related to the synthesis and analysis of compliant mechanisms continues to grow and mature. Building on this growth, a classification scheme has been established to categorize compliant elements and mechanisms in a manner that engineers can incorporate compliance into their designs. This paper demonstrates a design approach engineers can use to convert an existing rigid-body mechanism into a compliant mechanism by using an established classification scheme. This approach proposes two possible techniques that use rigid-body replacement synthesis in conjunction with a compliant mechanism classification scheme. One technique replaces rigid-body elements with a respective compliant element. The other technique replaces a complex rigid-body mechanism by decomposing the mechanism into simpler functions and then replacing a respective rigid-body mechanism with a compliant mechanism that has a similar functionality.
Analysis of Design Activities Using EEG Signals
Authors: Nguyen Thanh An , Zeng Yong
Published: March 2011

It plays a significant role in developing of design theory and methodology to understand designer’s thinking and cognitive process during design activities. The most dominant method to conduct this kind of study is protocol analysis. However, this method is prone to subjective factors. Therefore, other approaches are emerging, which can measure the brain activities directly. With the advances in technologies, brain scanner and brain recorder systems such as EEG, fMRI, PET have become more affordable. In the present research, we used EEG to record designer’s brain electrical signals when s/he was working on a design task. Six channels of the EEG signals were recorded, including Fp1, Fp2, Fz, Cz, Pz, Oz, based on which the power spectral density for each EEG band (delta, theta, alpha and beta) was calculated. The results showed that, for the given design problem, the subject spent more effort in visual thinking during the solution generation than that in solution evaluation. The preliminary success in identifying regularity underlying a single designer’s design process through EEG signals lays a foundation for further investigation of designers’ general mental efforts during the conceptual design process.
Stability Analysis for Haptic Rendering of Virtual Kelvin Viscoelastic Objects
Authors: Kerekes Tama´s , Bonakdar Ali , Ko¨vecses Jo´zsef
Published: March 2011

In this paper we investigate the stability properties of a single degree of freedom (DoF) haptic display while a virtual viscoelastic object is touched where the viscoelastic object is modeled using the standard linear solid model (also called the Kelvin model). We will demonstrate that this model leads to a discrete-time PID control-like representation of the virtual environment. A detailed dynamic analysis and simulations are presented in this paper with a particular attention to determine stability charts in the space of the parameters given by the virtual viscoelastic model.
Contact and Channel Modelling Using Part and Function Libraries in a Function-Based Design Approach
Authors: Albers Albert , Braun Andreas , Sadowski Eike , Wyatt David F. , Wynn David C. , Clarkson P. John
Published: March 2011

To support the development and analysis of engineering designs at the embodiment stage, designers work iteratively with representations of those designs as they consider the function and form of their constituent parts. Detailed descriptions of “what a machine does” usually include flows of forces and active principles within the technical system, and their localization within parts and across the interfaces between them. This means that a representation should assist a designer in considering form and function at the same time and at different levels of abstraction. This paper describes a design modelling approach that enables designers to break down a system architecture into its subsystems and parts, while assigning functions and flows to parts and the interfaces between them. In turn, this may reveal further requirements to fulfil functions in order to complete the design. The approach is implemented in a software tool which provides a uniform, computable language allowing the user to describe functions and flows as they are iteratively discovered, created and embodied. A database of parts allows the user to search for existing design solutions. The approach is illustrated through an example: modelling the complex mechanisms within a humanoid robot.
Constraint and Singularity Analysis of Lower-Mobility Parallel Manipulators With Parallelogram Joints
Authors: Amine Semaan , Kanaan Daniel , Caro Ste´phane , Wenger Philippe
Published: March 2011

This paper presents a general approach to analyze the singularities of lower-mobility parallel manipulators with parallelogram joints. Using screw theory, the concept of twist graph is introduced and the twist graphs of two types of parallelogram joints are established in order to simplify the constraint analysis of the manipulators under study. Using Grassmann-Cayley Algebra, the geometric conditions associated with the dependency of six Plu¨cker vectors of finite and infinite lines in the 3-dimensional projective space are reformulated in the superbracket in order to derive the geometric conditions for parallel singularities. The methodology is applied to three lower-mobility parallel manipulators with parallelogram joints: the Delta-linear robot, the Orthoglide robot and the H4 robot. The geometric interpretations of the singularities of these robots are given.
Nonlinear Vibrations of Cantilever Circular Cylindrical Shells
Authors: Amabili M. , Kurylov Ye.
Published: March 2011

Only experimental studies are available on large amplitude vibrations of cantilever shells. In the present paper, large-amplitude nonlinear vibrations of cantilever circular cylindrical shell are investigated. Shells with perfect and imperfect shape are studied. The Sanders-Koiter nonlinear shell theory, which includes shear deformation, is used to calculate the elastic strain energy. Shell’s displacement fields (longitudinal, circumferential and radial) are expanded by means of a double mixed series: harmonic functions for the circumferential variable; Chebyshev polynomials for the longitudinal variable. Boundary conditions are exactly satisfied. The Lagrangian approach is applied to obtain a system of nonlinear ordinary differential equations. The nonlinear equations of motion are studied by using arclength continuation method and bifurcation analysis. Numerical responses in the spectral neighborhood of the lowest natural frequency are obtained.
Dynamic Switching of MEMS Shunt Switches
Authors: Khater Mahmoud E. , Vummidi Krishna , Abdel-Rahman Eihab M. , Nayfeh Ali H. , Raman Sanjay
Published: March 2011

We investigate dynamic switching modes of capacitive MEMS shunt switches using a biased AC signal. We show that the voltage requirements for dynamic switching are significantly less than those for static switching. We found out that significant reductions in actuation voltage can be obtained. However, the switching time is longer than that realized using static switching. We also examine various actuation schemes to further reduce the actuation voltage. As a result, we obtain 60% reduction in the actuation voltage.