bluuebunny/crossref_metadata_2025 huggingface dataset:
Heating up the forest: open‐top chamber warming manipulation of arthropod communities at Harvard and Duke Forests
Authors: Pelini Shannon L. , Bowles Francis P. , Ellison Aaron M. , Gotelli Nicholas J. , Sanders Nathan J. , Dunn Robert R.
Published: March 2011

1. Recent observations indicate that climatic change is altering biodiversity, and models suggest that the consequences of climate change will differ across latitude. However, long‐term experimental field manipulations that directly test the predictions about organisms’ responses to climate change across latitude are lacking. Such experiments could provide a more mechanistic understanding of the consequences of climate change on ecological communities and subsequent changes in ecosystem processes, facilitating better predictions of the effects of future climate change.

2. This field experiment uses octagonal, 5‐m‐diameter (c. 22 m3) open‐top chambers to simulate warming at northern (Harvard Forest, Massachusetts) and southern (Duke Forest, North Carolina) hardwood forest sites to determine the effects of warming on ant and other arthropod populations and communities near the edges of their ranges. Each site has 12 plots containing open‐top chambers that manipulate air temperature incrementally from ambient to 6 °C above ambient. Because the focus of this study is on mobile, litter‐ and soil‐dwelling arthropods, standard methods for warming chambers (e.g. soil‐warming cables or infrared heaters applied to relatively small areas) were inappropriate and new technological approaches using hydronic heating and forced air movement were developed.

3. We monitor population dynamics, species composition, phenology and behaviour of ants and other arthropods occupying these experimental chambers. Microclimatic measurements in each chamber include the following: air temperature (three), soil temperatures (two each in organic and mineral soil), photosynthetically active radiation (PAR), relative humidity and soil moisture (one each). In two chambers, we are also measuring soil heat flux, associated soil temperatures at 2 and 6 cm and volumetric water content. To assess the composition, phenology and abundance of arthropod communities within the experiment, we use monthly pitfall trapping and annual Winkler sampling. We also census artificial and natural ant nests to monitor changes in ant colony size and productivity across the temperature treatments.

4. This experiment is a long‐term ecological study that provides opportunities for collaborations across a broad spectrum of ecologists, including those studying biogeochemical, microbial and plant responses to warming. Future studies also may include implementation of multifactorial climate manipulations, examination of interactions across trophic levels and quantification of changes in ecosystem processes.
Estimating survival in photographic capture–recapture studies: overcoming misidentification error
Authors: Morrison Thomas A. , Yoshizaki Jun , Nichols James D. , Bolger Douglas T.
Published: March 2011

1. For many species, noninvasive photographic identification offers a powerful and cost–effective method for estimating demographic parameters and testing ecological hypotheses in large populations. However, this technique is prone to misidentification errors that can severely bias capture–recapture estimates.

2. We present a simple ad hoc data conditioning technique that minimizes bias in survival estimates across all rates of misidentification. We use simulated data sets to characterize trade‐offs in bias, precision and accuracy of survival estimators for a range of misidentification probabilities, sampling intensities, survival rates and population sizes using this conditional approach.

3. Misidentification errors resulted in mean survival estimates that were negatively biased by as much as −24·9% when errors were ignored. Applying the conditional approach resulted in very low levels of bias across parameter space. However, the main cost of conditioning is a loss of precision, which was particularly severe at low sampling intensities. Overall, the conditional approach was superior to the nonconditional approach [in terms of root mean square error (RMSE) of survival estimates] in 51% of the parameter combinations that we explored.

4. We apply the data conditioning technique to a 3‐sample capture–recapture data set compiled from 2551 images of a migratory wildebeest, Connochaetes taurinus, population in northern Tanzania. We estimate the false rejection rate (i.e., the probability of failing to match two photographs of the same individual) using a test set of ‘known‐identity’ individuals. With this information, we compare survival estimates derived from conditioned data ( = 0·698 ± 0·176), unconditioned data ( = 0·706 ± 0·121) and simulated data to illustrate some of the key considerations for deciding whether to apply a conditional approach to a photographic data set.

5. These analyses demonstrate that ignoring misidentification error can lead to substantial bias in survival estimates. When sampling intensity and misclassification error rates are both relatively high, use of our conditioned data approach is preferred and yields survival estimates with lower RMSE. However, when sampling intensity and misclassification error are both small, the standard approach using unconditioned data yields smaller RMSE.
Reduced Mass-Weighted Proper Decomposition for Modal Analysis
Authors: Yadalam Venkata K. , Feeny B. F.
Published: March 2011

A method of modal analysis by a mass-weighted proper orthogonal decomposition for multi-degree-of-freedom and distributed-parameter systems of arbitrary mass distribution is outlined. The method involves reduced-order modeling of the system mass distribution so that the discretized mass matrix dimension matches the number of sensed quantities, and hence the dimension of the response ensemble and correlation matrix. In this case, the linear interpolation of unsensed displacements is used to reduce the size of the mass matrix. The idea is applied to the modal identification of a mass-spring system and an exponential rod.
Nanoscale Gd-Doped CeO2 Buffer Layer for a High Performance Solid Oxide Fuel Cell
Authors: Endler-Schuck Cornelia , Weber André , Ivers-Tiffée Ellen , Guntow Uwe , Ernst Johannes , Ruska Jürgen
Published: March 2011

Gd 2 O 3 -doped ceria (GCO) is irreplaceable as interface/buffer layer between a mixed conducting cathode such as La0.58Sr0.4Co0.2Fe0.8O3-δ (LSCF) and an 8 mol %Y2O3 stabilized ZrO2 (8YSZ) thin film electrolyte. To meet the demands of high performance, indispensable characteristics of this interface (LSCF/GCO/8YSZ) are (i) no reaction of GCO with LSCF or YSZ and (ii) a GCO layer that is defect-free (closed porosity, no cracks). It is well known that state-of-the-art screen printed and sintered GCO buffer layers are imperfect and ultimately reduce the overall performance. This study concentrates on the evaluation of nanoscaled GCO thin films integrated into anode supported cells (ASC). GCO thin films were deposited on 8YSZ electrolyte by a low temperature metal organic deposition (MOD) process. MOD is preferable because it is a versatile technique for large scale and low cost fabrication for various material compositions. The authors investigated the influence of preparation parameters with respect to chemical homogeneity and film quality (pores, cracks) of GCO thin films with a constant film thickness between 50 nm and 100 nm. Electrochemical performance of anode supported cells employing MOD derived GCO thin films will be presented in terms of ohmic resistance (ASRΩ) and will be evaluated in contrast to screen printed and sintered GCO thick films. Nanoscale MOD derived thin films with low processing temperatures and dense film qualities were vastly superior to state-of-the-art GCO and beneficial to the overall cell performance.
Microplane Model for Fracturing Damage of Triaxially Braided Fiber-Polymer Composites
Authors: Caner Ferhun C. , Bažant Zdeněk P. , Hoover Christian G. , Waas Anthony M. , Shahwan Khaled W.
Published: March 2011

A material model for the fracturing behavior for braided composites is developed and implemented in a material subroutine for use in the commercial explicit finite element code ABAQUS. The subroutine is based on the microplane model in which the constitutive behavior is defined not in terms of stress and strain tensors and their invariants but in terms of stress and strain vectors in the material mesostructure called the “microplanes.” This is a semi-multiscale model, which captures the interactions between inelastic phenomena such as cracking, splitting, and frictional slipping occurring on planes of various orientations though not the interactions at a distance. To avoid spurious mesh sensitivity due to softening, the crack band model is adopted. Its band width, related to the material characteristic length, serves as the localization limiter. It is shown that the model can realistically predict the orthotropic elastic constants and the strength limits. More importantly, the present model can also fit the tests of size effect on the strength of notched specimens and the post-peak behavior, which have been conducted for this purpose. When used in the ABAQUS software, the model gives a realistic picture of the axial crushing of a braided tube by a divergent plug.
Time and Temperature Dependent Recovery of Epoxy-Based Shape Memory Polymers
Authors: Castro Francisco , Westbrook Kristofer K. , Hermiller Jason , Ahn Dae Up , Ding Yifu , Qi H. Jerry
Published: March 2011

Shape memory polymers (SMPs) are a group of adaptive polymers that can recover the permanent shape from a temporary shape by external stimuli on demand. Among a variety of external stimuli for polymer actuation, temperature is the most extensively used. In SMP applications, one of the major design considerations is the time necessary to recover the shape without external deformation constraints, or free recovery, and the amount of the recoverable strain. This paper investigates the amount of the recoverable strain and the recovery rate of an epoxy-based SMP (Veriflex® E, VFE1-62 (CRG, Dayton, OH)) under different thermal conditions. In particular, the free recovery behaviors of the SMPs under two experimental protocols, isothermal and shape memory (SM) cycle, are studied. It is found that free recovery in isothermal experiments is much faster than that in a SM cycle at the same recovering temperature and the material is fully recoverable at the temperature above differential scanning calorimetry Tg. Furthermore, for the recovery in SM cycle experiments, reshaping the sample at a low temperature and recovering from the deformation at a high temperature yield the fastest recovery rate, while reshaping at a high temperature and recovering at a low temperature cannot recover the original shape within this work’s experimental time frame. The possible mechanism for these observations is discussed.
A Comparative Analysis of Energy Management Strategies for Hybrid Electric Vehicles
Authors: Serrao Lorenzo , Onori Simona , Rizzoni Giorgio
Published: March 2011

This paper presents a formalization of the energy management problem in hybrid electric vehicles and a comparison of three known methods for solving the resulting optimization problem. Dynamic programming (DP), Pontryagin’s minimum principle (PMP), and equivalent consumption minimization strategy (ECMS) are described and analyzed, showing formally their substantial equivalence. Simulation results are also provided to demonstrate the application of the strategies. The theoretical background for each strategy is described in detail using the same formal framework. Of the three strategies, ECMS is the only implementable in real time; the equivalence with PMP and DP justifies its use as an optimal strategy and allows to tune it more effectively.
Probability Density Function of Underwater Bomb Trajectory Deviation Due to Stochastic Ocean Surface Slope
Authors: Chu Peter C. , Fan Chenwu
Published: March 2011

Ocean wave propagation causes random change in an ocean surface slope and in turn affects the underwater bomb trajectory deviation (r) through a water column. This trajectory deviation is crucial for the clearance of obstacles such as sea mines or a maritime improvised explosive device in coastal oceans using bombs. A nonlinear six degrees of freedom (6DOF) model has been recently developed and verified at the Naval Postgraduate School with various surface impact speeds and surface slopes as model inputs. The surface slope (s) randomly changes between 0 and π/2 with a probability density function (PDF) p(s), called the s-PDF. After s is discretized into I intervals by s1,s2,…,si,…,sI+1, the 6DOF model is integrated with a given surface impact speed (v0) and each slope si to get bomb trajectory deviation r̂i at depth (h) as a model output. The calculated series of {r̂i} is re-arranged into monotonically increasing order ({rj}). The bomb trajectory deviation r within (rj, rj+1) may correspond to one interval or several intervals of s. The probability of r falling into (rj, rj+1) can be obtained from the probability of s and in turn the PDF of r, called the r-PDF. Change in the r-PDF versus features of the s-PDF, water depth, and surface impact speed is also investigated.
Horizontal Tubular Microalgae Photobioreactor Plant View Factors and Diffuse Radiation
Authors: Maor T. , Appelbaum J.
Published: March 2011

Different view factors and different components of the diffuse solar radiation impinging on a photobioreactor plant for cultivating microalgae products are formulated and calculated in the present article. The outdoor plant consists of multiple horizontal tubes arranged in multiple vertical walls. The diffuse radiation on a tube may come from three directions of the sky: from the aperture between the walls (from the sky above), from the penetration of the diffuse radiation between the tubes, and from the plant edges. Each component of the diffuse radiation is associated with a different view factor. For design parameters of a practical plant, the largest component of the diffuse radiation comes from the sky above the plant.
Analysis and Modeling of Plug-In Hybrid Electric Vehicle Charging Efficiency
Authors: Malek Alisyn , Muller Brett , Jayaraman Sowmyalatha
Published: March 2011

Based on 2007 data, the average energy consumption of an American household could increase by 23% with the addition of one Plug-In Hybrid Electric Vehicle (PHEV); this “sticker-shock” may impact the adoption of all PHEVs due to the unanticipated cost and time associated with vehicle charging. Furthermore, very few automotive standard work practices could identify and quantify this effect on the end consumer. To alleviate consumer reservations, vehicle plug-in charging must be designed to maximize the percentage of grid energy supplied to the battery and reduce the extra cost and time required to charge. Maximum efficiency can only be obtained through a systematic view of the charging process. Thus, the approach reviewed in this report considers not only the charger and EVSE (Electric Vehicle Supply Equipment) but also the RESS (Rechargeable Energy Storage System), the thermal management system, and the vehicle control modules. This report will outline a progression in charger system modeling techniques in the early vehicle development process and compare the results to empirical data. The goal of the report is to demonstrate the merit of including charging modeling as a portion of PHEV standard development work and stimulate discussion on systematic charging efficiency.
Case Study in Systematic Design Engineering: Trapeze Demonstration Rig
Authors: Eder W. Ernst
Published: March 2011

Students learning design engineering at times need a good example of procedure for novel design engineering. The systematic heuristic-strategic use of a theory to guide the design process — Engineering Design Science — and the methodical design process followed in this case study is only necessary in limited situations. The full procedure should be learned, such that the student can select appropriate parts for other applications. Creativity is usually characterized by a wide search for solutions, especially those that are innovative. The search can be helped by this systematic and methodical approach. This case example is presented to show application of the recommended method, and the expected scope of the output, with emphasis on the stages of conceptualizing. The case follows a novel design problem of a rig for a trapeze demonstration team to be used outdoors.
Fractional Mathieu Equation
Authors: Rand Richard H. , Sah Si M. , Suchorsky Meghan K.
Published: March 2011

After reviewing the concept of fractional derivative, we derive expressions for the transition curves separating regions of stability from regions of instability in the ODE: x″+(δ+εcost)x+cDαx=0 where Dαx is the order α derivative of x(t), where 0 < α < 1. We use the method of harmonic balance and obtain both a lowest order approximation as well as a higher order approximation for the n = 1 transition curves. We also obtain an expression for the n = 0 transition curves.
Parallel Biogeography-Based Optimization With GPU Acceleration for Nonlinear Optimization
Authors: Zhu Weihang
Published: March 2011

This paper presents a massively parallel Biogeography-based Optimization – Pattern Search (BBO-PS) algorithm with graphics hardware acceleration on bound constrained optimization problems. The objective of this study was to determine the effectiveness of using Graphics Processing Units (GPU) as a hardware platform for BBO-PS. GPU, the common graphics hardware found in modern personal computers (PC), can be used for data-parallel computing in a desktop setting. In this research, the BBO was adapted in the data-parallel GPU computing platform featuring ‘Single Instruction – Multiple Thread’ (SIMT). The global optimal search of the BBO was enhanced by the classical local Pattern Search (PS) method. The hybrid BBO-PS method was implemented in the GPU environment, and compared to a similar implementation in the common computing environment with a Central Processing Unit (CPU). Computational results indicated that GPU-accelerated SIMT-BBO-PS method was orders of magnitude faster than the corresponding CPU implementation. The main contribution of this paper was the parallelization analysis and performance analysis of the hybrid BBO-PS with GPU acceleration. The research result was significant in that it demonstrated a very promising direction for high speed optimization with desktop parallel computing on a personal computer (PC).
Technology-Oriented Optimization of the Secondary Design Parameters of Robots for High-Speed Machining Applications
Authors: Briot Se´bastien , Pashkevich Anatol , Chablat Damien
Published: March 2011

In this paper, a new methodology for the optimal design of the secondary geometric parameters (shape of links, size of the platform, etc.) of parallel kinematic machine tools is proposed. This approach aims at minimizing the total mass of the robot under position accuracy constraints. This methodology is applied to two translational parallel robots with three degrees-of-freedom (DOF): the Y-STAR and the UraneSX. The proposed approach is able to speed up the design process and to help the designer to find more quickly a set of design parameters.
Curvature Theory of the Envelop Curve / Surface for a Line in Planar Motion and a Plane in Spatial Motion
Authors: Wang Wei , Wang Delun
Published: March 2011

The curvature theories for the envelop curve of a line in planar motion and the envelop ruled surface of a plane in spatial motion are extensively researched in the differential geometry language. A line-envelop curve in planar motion is firstly derived by means of the adjoint approach. The higher order curvature theory of the envelop curve reveals a unified form in the infinitesimal and finitely separated positions for a line in planar motion. And then, a plane in spatial motion traces the envelop surface, which is a developable surface and whose invariants are concisely derived. The geodesic curvature of the spherical image curve for the generator’s unit vector is readily derived and compared with that of the unit normal vector of the envelop surface. As a result, the curvature theory for a plane-envelop surface in spatial motion are shown in terms of that of the spherical motion, corresponding to the generator’s unit vector and unit normal vector of the envelop surface. Meanwhile, the instantaneous cubic (cone) of stationary curvature and the direction “Burmester’s line” of the generator of the developable envelop surface are revealed. Therefore, a solid theoretical basis is provided for the synthesis of mechanisms and the machining of surface.
On the Boundaries of the Wrench-Closure Workspace of Planar Parallel Cable-Driven Mechanisms
Authors: Azizian K. , Cardou P. , Moore B.
Published: March 2011

The wrench-closure workspace of parallel cable-driven mechanisms is the set of poses for which any wrench can be produced at the end-effector by a set of a non-negative cable tensions. It is already known that the boundary of the constant-orientation wrench-closure workspace of a planar parallel cable-driven mechanism is composed of segments of conic sections. However, the relationship between the geometry of the mechanism and the types of these conic sections is unknown. This paper proposes a graphical method for determining the types of these conic sections. It is also shown that the proposed method can be applied to find the constant-orientation singularities of a 3-RPR planar parallel robot, since these contours correspond to the boundary segment of the analogous three-cable driven planar parallel mechanism.
On the Manipulability of the Center of Mass of Humanoid Robots: Application to Design
Authors: Cotton Sebastien , Fraisse Philippe , Murray Andrew P.
Published: March 2011

This paper proposes an analysis of the manipulability of the Center of Mass (CoM) of humanoid robots. Starting from the dynamic equations of humanoid robots, the operational space formulation is used to express the dynamics of humanoid robots at their CoM and under their specific characteristics: a free-floating base, forces at contact points, and dynamic balance constraints. After a review of the kinematic manipulability of the CoM, the concept of dynamic manipulability of the CoM is introduced. The latter represents the ability of a humanoid robot to generate a spatial motion under a stability criterion. The size and shape of the dynamic manipulability of the CoM are a function of the joint torque limitations, the contact forces and the zero moment point used as a stability criteria. Two calculations of the CoM dynamic manipulability are proposed, a fast ellipsoid approximation, and the exact polyhedron computation. A case study illustrates the proposed approach on the HOAP3 humanoid robot and its use for mechanical design optimization.
Nonlinear Vibrations of Partially Fluid-Filled Cylindrical Shells
Authors: Gonc¸alves Paulo B. , da Silva Frederico M. A. , del Prado Zeno´n J. G. N.
Published: March 2011

The present work investigates the nonlinear dynamic behavior and instabilities of partially fluid-filled cylindrical shell subjected to lateral pressure. Donnell shallow shell theory is employed to model the shell. The fluid is modeled as non-viscous and incompressible and its irrotational motion is described by a velocity potential which satisfies the Laplace equation. A discrete low-dimensional model for the nonlinear vibration analysis of thin cylindrical shells is derived to study the shell vibrations. First, a general expression for the nonlinear vibration modes that satisfy all the relevant boundary, continuity and symmetry conditions is derived using a perturbation procedure validated in previous studies and then the Galerkin method is used to discretize the equations of motion. The same modal solution is used to derive the hydrodynamic pressure on the shell wall. The influence played by the height of the internal fluid on the natural frequencies, nonlinear shell response and bifurcations is examined.
Introduction to Pre-Robotics: Exploring a Novel Approach for Teaching Mechanical Design
Authors: Payandeh Shahram
Published: March 2011

Educating young engineers in the field of design has always been a challenging task. In particular, teaching some of the aspects of robotics and mechanisms design in a non-mechanical curriculum by far introduces additional challenges. This paper presents an overview of a teaching approach and pedagogical challenges of the author for the past 18 years in teaching (or creating a learning objectives) of the basics of mechanical design methodologies and experiences to sophomore students enrolled in the Engineering Science program. One of the main components of the course syllabus is the notion of design synthesis of a pre-robotic mechanical device. First, the functionality of this device is shown to the students. Next, the students need to propose various design alternatives with mechanical and technical specifications. This paper outlines the method of how the students are guided through the design experience while exploring the basic steps of the design process and specifications.
Frequency Response Behavior of Microcantilevers in Tapping-Mode Atomic Force Microscopy
Authors: Delnavaz Aidin , Mahmoodi S. Nima , Jalili Nader , Zohoor Hassan
Published: March 2011

Distributed-parameters vibration model of microcantilevers in tapping-mode Atomic Force Microscopy (AFM) is developed and is shown to be highly nonlinear. The question of why these nonlinearities are important and how they influence the predicted frequency response behavior of the cantilevers is addressed by comparing the results of developed model with a simple lumped-parameters model that has been extensively studied in the literature so far. The interaction forces between the microcantilever tip and the sample is supposed to be the same in both models and consist of attractive and repulsive interaction force regimes. In addition, experimental measurements are provided for a typical microcantilever-sample system to demonstrate the superiority of distributed-parameters formulation over the lumped-parameters model to predict the frequency response behavior of the AFM prob. The results indicate that the nonlinear continuous model is more accurate particularly in the estimation of the saturated amplitude and frequency zone in which the tip-sample contact occurs.
A General Methodology for the Forward Kinematic Problem of Symmetrical Parallel Mechanisms and Application to 5-PRUR Parallel Mechanisms (3T2R)
Authors: Tale Masouleh Mehdi , Husty Manfred , Gosselin Cle´ment
Published: March 2011

In this paper, a general methodology is introduced in order to formulate the FKP of symmetrical parallel mechanisms in a 7-dimensional projective space by the means of the so-called Study’s parameters. The main objective is to consider rigid-body displacement, and consequently the FKP, based on algebraic geometry, rather than rely on classical recipes, such as Euler angles, to assist in problem-solving. The state of the art presented in this paper is general and can be extended to other types of symmetrical mechanisms. In this paper, we limit the concept of kinematic mapping to topologically symmetrical mechanisms, i.e., mechanisms with limbs having identical kinematic arrangement. Exploring the FKP in a higher dimensional space is more challenging since it requires the use of a larger number of coordinates. There are, however, advantages in adopting a large set of coordinates, since this approach leads to expressions with lower degree that do not involve trigonometric functions.
Tweezers for Micromanipulation With Grasp Detection of Small Object
Authors: Furutani Katsushi , Makino Taizo
Published: March 2011

This paper deals with tweezers using bimorph piezoelectric actuators for micromanipulation. It measures 51 mm × 24 mm × 10 mm and weighs 62 g including electric cables of 27 g. Each finger consists of a bimorph piezoelectric actuator with a stainless steel tip. The tweezers open and close by driving both the actuators synchronously. One of the tweezers (vibrator) is oscillated by rectangular wave at its resonance frequency, and another (receiver) detects the vibration. When the tweezers grasp an object, the receiver is vibrated through the object. By using a lock-in amplifier with a reference signal, noise components can be eliminated. The resonance frequency was analyzed by finite element method and experiments. They almost agreed each other. Glass beads with a diameter of 60–70 μm could were grasped. The tweezers were used for micromanipulation.
Model Parameter Identification of Nonlinear Dynamics Systems by Trajectory Pattern Method
Authors: Rastegar Jahangir , Feng Dake , Jorabchi Kavous
Published: March 2011

In this paper, a new method is presented for model parameter identification of a large class of fully controlled nonlinear dynamics systems such as robot manipulators. The method uses trajectory patterns with feed-forward controls to identify model parameters of the system. The developed method ensures full system stability, does not require close initial estimated values for the parameters to be identified, and provides a systematic method of emphasizing on the estimation of the parameters associated with lower order terms of the system dynamics model and gradually upgrading the accuracy with which the model parameters, particularly those associated with the higher order terms of the system dynamics model are estimated. The developed method is based on Trajectory Pattern Method (TPM). In this method, for a pattern of motion the inverse dynamics model of the system is derived in algebraic form in terms of the trajectory pattern parameters. The system dynamics model parameters are then identified using a systematic algorithm which ensures system stability as well as accurate estimation of the model parameters associated with lower as well as higher order terms. Mathematical proof of convergence of the developed method and an example of its application are provided.
Using an In-Situ Micromirror to Assist the Measurement of In-Plane Vibration of Microstructures
Authors: Chow Jacky , Lai Yong-Jun
Published: March 2011

Heterodyne laser interferometry is an optical technique often used to measure displacement of surfaces along the wave vector direction of a measurement laser. For common microelectromechanical system (MEMS) testing setup, such laser wave vector is perpendicular to the substrate which the micromachined devices stand on. Therefore, this technique can only be used to characterize dynamics of the micro devices in the direction perpendicular to their substrate (out-of-plane motions) with the classic setup and it is not able to measure any motion that is parallel to the substrate (in-plane motions). In this study, in-situ micromirrors are fabricated onto a microstructure that is near the device to be measured by using a focused ion beam system. The micromirrors have a slant angle of approximate 45 degree to horizontal surface (or their substrate). By using the post-fabricated in-situ micromirror, the measurement laser of a heterodyne interferometer can be directed into horizontal plane which enables characterization of in-plane motions for micromechanical. To experimentally demonstrate the technique a micro cantilever fabricated using MetalMUMPs is used. The micro cantilever is excited by inplane electrostatic force. The results confirm the effectiveness of the method by the fact that the magnitude of the measured in-plane signal is increased by more than ten folds.
An Analysis on Sliding of Biped Robots
Authors: Liu C. H. , Wu Chi-Hwa , Wang Yin-Tien
Published: March 2011

In this paper we study the instability of biped robots that is a combination of both sliding and tipping over. Specifically, when robot falling occurs, the ground reaction forces and moments on a foot may determine if sliding also happens. We deal with the situation that tipping over is impending, and treat the following three possible types of contact stress distribution on the foot: point contact, line contact, and area contact. In line and area contact regions we assume that normal stresses are Hertzian, then tangential stresses may be determined by utilizing theory of instantaneous center of zero velocity in planar kinematics. From these normal and tangential stresses we may determine force combinations that cause sliding.
A Method for Extraction of Causal Relations Between Product Design Attributes and Sensory Responses Considering Diversity of Evaluators’ Visual Attention
Authors: Yanagisawa Hideyoshi , Tagashira Kyosuke , Murakami Tamotsu
Published: March 2011

In the design of kansei (emotional) quality, one of the important issues is to extract causal relations between physical design attributes and the customer’s emotional responses. Without such relations, a designer has to rely on his/her own sense that may be different from the customer’s. In this paper, we propose a new method for extraction of logical rules consisting of combinations of design attributes that explain a customer’s emotional judgment towards product appearance. In the method, we apply a reduct calculation in rough set theory to derive alternatives of causal rules between design attributes and emotional judgments, and use the customer’s eye gaze features for refining the rules. We extract two types of visual attentions (VA), i.e., a single visual attention (SVA) and a combinational visual attention (CVA), by using the proposed gaze features. To demonstrate the effectiveness of the method, we conducted a sensory evaluation experiment using a car-interior design as a case study. In the experiment, multiple participants evaluated impressions of multiple design samples by selecting from a set of words. During the experiment, we recorded the participants’ eye gaze movements as coordinates on a screen, and asked them to vocalize aloud what they were thinking. After an evaluation of each design sample, we conducted a retrospective interview. From the results, we confirmed that the estimated SVA and CVA significantly covered the vocalized thoughts and statements made in the retrospective interview. The estimated VA reduced 53% of the erroneous causal rules and improved the quality of the rules. We found a case where two participants making the same emotional judgments have implicitly different points of view when evaluating the same design sample. Most conventional causality analysis has been unsuccessful in finding such diversity of points of view.
Evaluating the Impacts of Iteration on PD Processes by Transforming Task Network Models Into System Dynamics Models
Authors: Le H. Nam , Wynn David C. , Clarkson P. John
Published: March 2011

Iteration is unavoidable in the design process and should be incorporated when planning and managing projects in order to minimize surprises and reduce schedule distortions. However, planning and managing iteration is challenging because the relationships between its causes and effects are complex. Most approaches which use mathematical models to analyze the impact of iteration on the design process focus on a relatively small number of its causes and effects. Therefore, insights derived from these analytical models may not be robust under a broader consideration of potential influencing factors. In this article, we synthesize an explanatory framework which describes the network of causes and effects of iteration identified from the literature, and introduce an analytic approach which combines a task network modeling approach with System Dynamics simulation. Our approach models the network of causes and effects of iteration alongside the process architecture which is required to analyze the impact of iteration on design process performance. We show how this allows managers to assess the impact of changes to process architecture and to management levers which influence iterative behavior, accounting for the fact that these changes can occur simultaneously and can accumulate in non-linear ways. We also discuss how the insights resulting from this analysis can be visualized for easier consumption by project participants not familiar with simulation methods.
A Velocity Metric for Rigid-Body Planar Motion
Authors: Schimmels Joseph M. , Criales Luis E.
Published: March 2011

A planar rigid-body velocity metric based on the instantaneous velocity of all particles that constitute a rigid body is developed. A measure based on the discrepancy in the translational velocity at each particle for two different planar twists is introduced. The calculation of the measure is simplified to the calculation of the product of: 1) the discrepancy in angular velocity, and 2) the average distance of the body from the instantaneous center associated with the twist discrepancy. It is shown that this measure satisfies the mathematical requirements of a metric and is physically consistent. It does not depend on either the selection of length scale or the frames used to describe the body motion. Although the metric does depend on body geometry, it can be calculated efficiently using body decomposition. An example demonstrating the application of the metric to an assembly problem is presented.
Multiple-Criteria Kinematic Optimization for the Design of Spherical Serial Mechanisms Using Genetic Algorithms
Authors: Zhang Xiaoli , Nelson Carl A.
Published: March 2011

A new kinematic design methodology is presented for optimization of spherical serial mechanisms. This method integrates multiple criteria (workspace, manipulability, and size) linearly in one objective function. All these criteria are optimized simultaneously to lead to a more realistic solution. By changing the priorities of each criterion, different sets of desirable kinematic performance can be expressed. The global manipulability and the uniformity of manipulability over the workspace are combined in a single index to improve the synthesis results. The optimization result for a spherical bevel-geared mechanism using a genetic algorithm demonstrated that the proposed method effectively improves the quality of the optimum solution and provides insight into the workings of the mechanism. In addition, this flexible and adaptable methodology may also be extended for use in general optimization for linkage synthesis.
On the Dynamic Modeling of a Bevel-Geared Surgical Robotic Mechanism
Authors: Zhang Xiaoli , Nelson Carl A.
Published: March 2011

The use of robotics to enhance visualization and tissue manipulation capabilities is contributing to the advancement of minimally invasive surgery (MIS). For the development of surgical robot manipulators, the use of advanced dynamic control is an important aspect at the design stage to determine the driving forces and/or torques which must be exerted by the actuators in order to produce a desirable trajectory of the end effector. Therefore, this study focuses on the generation of inverse dynamic models for a spherical bevel-geared mechanism called CoBRASurge (Compact Bevel-geared Robot for Advanced Surgery), which is used as a surgical tool manipulator. For given typical trajectories of end effectors in clinical experiments, the motion of each element in the mechanism can be derived using the inverse kinematic equations. The driving torques exerted by actuators can be determined according to the presented inverse dynamic formulations. The simulation results of CoBRASurge reveal the nature of the driving torques in spherical bevel-geared mechanisms. Such models can be used for the design of advanced dynamic control systems, including gravity compensation and haptic interfaces for enhanced surgical functionality. In addition, sensitivity analysis of mass contribution has been performed to evaluate the effect of individual elements on the peak driving torques, which provides a solid guideline for the design of the next-generation CoBRASurge prototype. The present dynamic modeling methodology also presents a general dynamic analysis approach for other spherical articulated linkage mechanisms.
Redundancy Parameterization for Flexible Motion Control
Authors: Moore B. , Oztop E.
Published: March 2011

Our overall research interest is in synthesizing human like reaching and grasping using anthropomorphic robot hand-arm systems, as well as understanding the principles underlying human control of these actions. When one needs to define the control and task requirements in the Cartesian space, the problem of inverse kinematics needs to be solved. For non-redundant manipulators, a desired end-effector position and orientation can be achieved by a finite number of solutions. For redundant manipulators however, there are in general infinitely many solutions where the cardinality of the solution set must be made finite by imposing certain constraints. In this paper, we consider the Mitsubishi PA10 manipulator which is similar to the human arm, in the sense that both wrist and shoulder joints can be considered to emulate a 3DOF ball joint. We explicitly derive the analytic solution for the inverse kinematics using quaternions. Then, we derive a parameterization in terms of a pure quaternion called the swivel quaternion. The swivel quaternion is similar to the elbow swivel angle used in most approaches, but avoid the computation of inverse trigonometric functions. This parameterization of the self-motion manifold is continuous with any end-effector motion. Given the pose of the end-effector and the swivel quaternion (or swivel angle), the algorithm derives all solution of the inverse kinematics (finite number). We then show how the parameterization of the elbow self-motion can be used for the real-time control of the PA10 manipulator in the presence of obstacles.
User Interface Design for Interactive Product Family Analysis and Variants Derivation
Authors: Lim Soon Chong Johnson , Loh Han Tong , Liu Ying
Published: March 2011

Product family design (PFD) is one of the commonly adopted strategies of product realization in mass customization paradigm. Among the current product family modeling approaches, ontology based modeling has been identified as a promising approach. Previously, we have studied the feasibility of using a semantically annotated multi-facet product family ontology in performing product analysis and variant derivation in the PFD domain. However, the visualization aspects of the ontology are important to assist product designers and engineers to gain insights and benefit from the ever-increasing information from the ontology, e.g. dimension, assembly or configuration wise. From the previous literature, we observe that there are limited usage of visualization and interaction in PFD for tasks such as product analysis and variant derivation. The current hierarchy based representations are limited in displaying ontological relationships and tasks such as commonality analysis seldom make use of visualization to foster better understanding of component similarity. In this study, we report our efforts in assisting product family analysis and variant derivation through visualization and user interface (UI) which enables interactive PFD. Design considerations for our visualization and user interaction design are discussed. By using a multi-touch UI, we discuss on how our UI is able to enable users to better perform product analysis and variant derivation based on the aforementioned ontology in an interactive, intuitive and intelligent manner. We finally conclude this paper with some indications for future works.
Optimal Camera Path Planning for the Inspection of Printed Circuit Boards Using a Two Stepped Optimization Approach
Authors: Hermes Zainab , Nassef Ashraf O. , Gaafar Lotfi K.
Published: March 2011

Automated Optical Inspection (AOI) systems are rapidly replacing slow and tedious manual inspections of Printed Circuit Boards (PCBs). In an AOI system, a minicamera traverses the PCB in a pre-defined travel path, snapping shots of all the PCB components or nodes, at pre-defined locations. The images are then processed and information about the different nodes is extracted and compared against ideal standards stored in the AOI system. This way, a flawed board is detected. Minimizing both the number of images required to scan all the PCB nodes, and the path through which the camera must travel to achieve this, will minimize the image acquisition time and the traveling time, and thus the overall time of inspection. This consequently both reduces costs and increases production rate. This work breaks down this problem into two sub-problems: The first is a clustering problem; the second a travelling salesman sequencing problem. In the clustering problem, it is required to divide all the nodes of a PCB into the minimum number of clusters. The cluster size is constrained by the given dimensions of the camera’s scope or Field of Vision (FOV). These dimensions determine the dimension of the inspection windows. It is thus required to find the minimum number of inspection windows that will scan all the nodes of a PCB, and their locations. Genetic algorithms are applied in a two-step approach with special operators suited for the problem. A continuous Genetic Algorithm (GA) is applied to find the optimum inspection window locations that cover one node and as many other nodes as possible. A discrete GA is then applied to eliminate redundant inspection windows leaving the minimum number of windows that cover all nodes throughout the PCB. In the second sub-problem, an Ant Colony Optimization (ACO) method is used to find the optimum path between the selected inspection windows. The method proposed in this paper is compared against relevant published work, and it is shown to yield better results.
The Tactile Window: A Haptic Tool for Material Selection
Authors: Vanhuysse Sarah J. M. , Westebring-van der Putten Eleonora P. , Bergmann Tiest Wouter M. , Horva´th Imre
Published: March 2011

In this article a haptic tool for industrial designers is presented. The tool should aid them in material selection for product experience and fit in an advanced design studio: the Tangible Virtual Reality environment. A study of related work suggests that six touch sensations are essential in this context. A solution idea for multi-sensation feedback was developed and its intended behavior and functionalities defined. A first concept combines two of the relevant sensations: texture and warmth, the former displayed by a piezo-driven pin array and the latter by a peltier element acting as a heat pump. A simple experiment — matching displayed stimuli to real materials — was conducted to prove the feasibility of the concept. Experimental results confirm that the prototype gives the impression of a certain surface, but the absence of four relevant sensations limits the experience’s realism. However promising, these results confirm the desirability of further integration of touch sensations in one device.