bluuebunny/crossref_metadata_2025 huggingface dataset:
Strongly Nonlinear Spatially Periodic Traveling Waves in Granular Dimer Chains
Authors: Jayaprakash K. R. , Vakakis Alexander F. , Starosvetsky Yuli
Published: September 2013

In the present work we study the dynamics of spatially periodic traveling waves in granular 1:1 (each bead is followed and preceded by a bead of different mass and/or stiffness) dimer chain with no pre-compression. The dynamics of a 1:1 dimer chain is governed by a single parameter, the mass ratio of the two beads forming each dimer pair of the chain. In particular, we demonstrate numerically the formation of special families of traveling waves with spatially periodic waveforms that are realized in semi-infinite dimer chains with the application of an arbitrary impulse. These traveling waves were first observed in the form of oscillatory tails in the trail of the propagating primary pulse. The energy radiated by the propagating primary pulse manifests in the form of traveling waves of varying spatial periodicity depending on the mass ratio. These traveling waves depend only on the mass ratio and are rescalable with respect to any arbitrary applied energy. The dynamics of these families of traveling waves is systematically studied by considering finite dimer chains (termed the ‘reduced systems’) subject to periodic boundary conditions. We demonstrate that these waves may exhibit interesting bifurcations or loss of stability as the system parameter varies. In turn, these bifurcations and stability exchanges in infinite dimer chains are correlated to previous studies of pulse attenuation in finite dimer chains through efficient energy radiation from the propagating pulse to the far field, mainly in the form of traveling waves. Based on these results a new formulation of attenuation and propagation zones (stop and pass bands) in semi-infinite granular dimer chains is proposed.
The Study of the Initial State of Cable-Net Structure Reflector for the FAST
Authors: Liu Yu , Gao Feng
Published: September 2013

By using the variational principle to set up the mathematical model of the reflector for the FAST, we can get the node location of the cable-net and tension of the main cable by solving highly nonlinear equations of the mathematical model. A new layer-by-layer substitution approach has been proposed for solving the highly nonlinear equations, through the calculation and simulation it verifies the correctness of this method.
Modeling Tape Cast Ceramics With Layers of Fugitive Phases
Authors: Wimmer Stephanie A. , Pan Ming-Jen , DeGiorgi Virginia G. , Gorzkowski Edward P.
Published: September 2013

New fabrication methods for topologically complex monolithic ceramic components with accurate dimensions are being investigated. A common problem in the fabrication of precision ceramic components is controlling the forming process to attain uniform density in the green body; otherwise the tolerances achieved with green ceramics do not carry over to acceptable tolerances on the finished ceramic due to distortion and warping that occur during sintering. One of the fabrication methods under study is the fugitive phase approach in which a sacrificial material is used to form the desired channels and cavities. This paper is a continuation of previously presented work and examines the lamination step of the fugitive phase approach. In the lamination step, the green, pre-sintered, ceramic parts are layered with the sacrificial material parts and pressed together to remove air voids. During pressing uneven pressure distributions can be created in the green ceramic and the fugitive phase parts are slightly displaced or rotated. A computational model of the lamination process is used to examine how the material plasticity of the green ceramic, computational boundary conditions, and pressing duration affect the resulting geometry produced at the end of the lamination step prior to sintering. The resting stress, plastic strain, and deformed shapes are examined and compared. This information is used to complement experimental investigations of the fugitive phase approach.
Mechanical Behavior Analysis of Micro-Scaled Functionally Graded Timoshenko Beams by the Strain Gradient Theory
Authors: Tajalli S. A. , Kahrobaiyan M. H. , Rahaeifard M. , Ahmadian M. T. , Movahhedy M. R. , Akbari J.
Published: September 2013

In this paper, a size-dependent formulation is developed for Timoshenko beams made of functionally graded materials (FGM). The developed formulation is based on the strain gradient theory; a non-classical continuum theory able to capture the size-effect in micro-scaled structures. Considering the material length scale parameters of the FG beams vary through the thickness, the new equivalent length scale parameters are proposed as functions of the constituents’ length scale parameters to describe the size-dependent static and dynamic behavior of FG microbeams. The governing differential equations of equilibrium and both classical and non-classical sets of boundary conditions are derived for the proposed strain gradient FG Timoshenko beam using variational approach. As case studies, the static bending deformation of the new model is investigated for an FG simply supported beam made of tungsten/copper (W/Cu) in which properties are varying through the thickness according to a power law. The results of the new model are compared to those of the modified couple stress and the classical theories where the two latter theories are special cases of the strain gradient theory.
Automated Estimation of Time and Cost for Determining Optimal Machining Plans
Authors: Van Blarigan Benjamin , Campbell Matthew I. , Eftekharian Ata A. , Kurtoglu Tolga
Published: September 2013

In any manufacturing setting, producing a machined part is a complicated, multi-step process. It requires coordination between an engineer and a machinist to ensure all goals are met. A machinist creates a part based generally on personal experience and intuition, and while they know that this will result in the finished product, it is not guaranteed that the process plan chosen is the quickest or least expensive way to make the part. In the past year, we have been developing an automated tool that analyzes a solid model to determine its best process plan. The tool is essentially comprised of a reasoning engine that determines what processes are valid for particular sections of the part, and an evaluation engine that estimates the time and cost of the candidate processes.

This paper presents the implemented evaluation engine, which assigns individual values of time and cost to machine operations. The evaluation starts with an automated tool selection strategy. The engineering model is able to determine the machining time of the tool(s) chosen. The method presented here takes a unique approach to machining time estimation that balances the trade-off between accuracy and computational time. Preliminary results suggest that the method is able to achieve accuracy near that of commercial CAM packages, with a much lower computational expense. The evaluation model takes into account non-productive manufacturing times (e.g. fixturing, inspection), and translates these to related costs. The method will be presented and discussed in this paper along with some preliminary results.
Motion Capture and Virtual Humans to Enhance Ergonomic Design and Validation of Refrigerated Display Units
Authors: Colombo Giorgio , De Vecchi Giordano , Regazzoni Daniele , Rizzi Caterina
Published: September 2013

This paper presents a computer-aided environment to analyze postures and movements in order to ergonomically validate the design of potentially any device a man or woman may have to deal with. The proposed environment integrates virtual prototyping techniques with Digital Human Modeling and Motion Capture techniques to determine fatigue, stress and risk for workers’ health. We considered a vertical refrigerated display unit as case study to analyze the interaction of supermarket staff filling the shelves with goods with the main goal determining the suitability of operators’ working condition and, eventually, providing a feedback to the design step.

The paper, after a brief description of the state of the art of the Motion Capture system and Digital Human Modeling, presents the architecture of the integrated environment developed and the working paradigm. At last preliminary results of the experimentation as well benefits and the limits of the outcomes achieved so far in the automation of ergonomics in machines design are presented.
Development of a Storage Retrieval Machine for High Racks Using a Wire Robot
Authors: Bruckmann Tobias , Lalo Wildan , Nguyen Khoa , Salah Bashir
Published: September 2013

Intralogistics systems are a rapidly growing market. Today, high racks and automated storage retrieval machines are widely used to store and handle industrial goods. Conventional storage retrieval machines show a major drawback: While the containers or goods to be moved are often very lightweight, the storage retrieval machine itself may weight up to two tons which limits the energy efficiency and the motion capabilities. This limitation is a problem since the reduction of cycle times is crucial in logistics applications. Therefore, faster motions are desired. At the same time, a main focus in intralogistics development is on energy-saving solutions as part of the ongoing climate change debate. Together with the rising energy costs, this paves the way for radical new concepts which go beyond the lightweight construction of conventional storage retrieval machines. Recently, a huge research project started to realize an alternative approach for a storage retrieval machine system. This approach uses a parallel wire robot system to move the goods to be stored to the desired position. The system is extremely lightweight and therefore, fast motions are possible while the required energy is comparably low. Therefore, cycle times for the transport of the goods can be drastically reduced which is crucial in this application. The paper presented here describes both design concepts which were already presented, as well as optimized geometries which are superior in terms of workspace coverage and stiffness. First simulation results are shown and discussed with a focus on the potential of the system for precise loading and unloading of containers. Besides that, the overall mechatronic system design is introduced.
A Discrete Differential Evolution Algorithm for Product Development Scheduling
Authors: Nonsiri Sarayut , Coatanea Eric , Bakhouya Mohamed
Published: September 2013

The scheduling of the design activities in product development process is a crucial step in early stages in order to achieve the project in time and cost-effective manner. In complex product development process, many dependency relationships or feedback loop could exist between design activities with multiple technical domains. Sequencing the design activities is a decision making process in order to reduce these feedback loops, and therefore, reduce amount of required information flows between activities. In recent years, methods for sequencing the design activities in design process have been proposed in order to reduce lead-time development and cost. The purpose of this research work is to present a methodology for design process sequencing in product development project by using Design Structure Matrix (DSM) for visualization a complex process and Discrete Differential Evolution (DDE) for sequencing the design tasks. The tests performed in this article have shown that this approach provides very competitive results in term of the quality of obtained solutions when compared to Genetic algorithms (GA). In additional it is a simple, effective and easy to use since the amount of control parameters to set is reduced.
Subatomic Resolution in Noncontact Atomic Force Microscopy: Electron Cloud Interactions or Harmonics Processing Artifacts?
Authors: Wright C. Alan , Solares Santiago D.
Published: September 2013

In 2004 Hembacher et al. [Science 305, 380–383 (2004)] reported higher harmonics AFM images of a graphite surface acquired using a tungsten tip which revealed subatomic features. These features were interpreted as the signature of electron bonding lobes at the tip apex atom. We recently applied a computational method based on density functional theory to simulate the images of Hembacher et al. and found that features of subatomic size can indeed be observed under ideal conditions. However, a number of important questions remain open, the most significant of which concerns signal processing. Here we continue our bottom-up analysis by exploring the effects of harmonics processing on the images obtained. Our simulations suggest that there are no imaging artifacts inherent to the filtering process used but that harmonics averaging is not an appropriate method for enhancing subatomic contrast due to variations in the harmonics ratios across the surface. Instead, a promising approach may be the individual mapping of the first two harmonics, which are expected to dominate the contrast under the conditions studied by Hembacher et al.
Nonlinear Free Dynamic Response of a One Degree-of-Freedom Oscillator Induced by a Quadratic Velocity Dependent Model of Friction
Authors: Majdoub Fida , Perret-Liaudet Joël , Belin Michel , Martin Jean-Michel
Published: September 2013

In this paper, we study a kinematic friction model of a single degree-of-freedom oscillating system. This model has the following dimensionless equation of motion: y″+2ζy′+y=-μky′ in which the kinematic friction is described by a quadratic function of the velocity as the following: μky′=μ0+μ2y′2sgny′+μ1y′ The sign function preserves the asymmetry of the friction force. The model captures most of the friction behavior that has been observed experimentally using a recent apparatus known as “dynamic oscillating tribometer”. This experimental setup is based on the non-linear free dynamic response of this kind of oscillator. However, this technique is able to carefully determine, with no need for any force transducer, the velocity-independent and velocity-dependent friction coefficients, μ0 and μ1 respectively, for a linear description of the kinematic friction, μk, around y′ = 0 where: μky′=μ0sgny′+μ1y′ In this context, the principal aim is to investigate numerically and analytically the effect of the additional quadratic term. To analyze the free dynamic response and their corresponding envelops, different numerical methods are performed. New characteristics of the envelops are discussed in detail with respect to the form of the kinematic friction coefficient. This allows a better comprehension of the results observed experimentally.
Extracting Dynamic Information From Whole-Building Energy Models
Authors: Eisenhower Bryan , Mezić Igor
Published: September 2013

Whole-building energy models are used in practice to predict energy and comfort for an entire building given its architectural and built state, external stimuli from weather, and internal behavior of both the equipment and occupants of the building. There exists both open source and commercial software for simulating such cases for an entire year at sub-hourly reporting intervals. Unfortunately, the dynamics of the building are masked in assumptions included in the numerical routines that are often intertwined within the thermal physics. Because of this, control-oriented analysis is limited to performing exhaustive time-based simulations. In this paper, we describe a method to analytically extract the dynamics from a whole-building energy simulator for the purpose of control and dynamical systems analysis. In this way, the function of the energy simulator is only a user interface and a means to organize information inherent in the dynamics (capacitances, interaction between elements of the building, etc.). We provide a test case on a medium office building and illustrate some of its control-oriented dynamic properties using EnergyPlus as the simulator.
Improved Elliptical Trainer Biomechanics Using a Modified Cardan Gear
Authors: Nelson Carl A. , Burnfield Judith M.
Published: September 2013

Although many different kinematic structures have been employed in the design of elliptical machines for exercise and fitness, these devices in general do not produce pedal paths that promote lower extremity kinematics similar to overground gait. This is unfortunate given the growing interest in using these devices as a gait rehabilitation tool. In this paper, we present a novel design strategy for elliptical machines intended to create a movement profile that more closely simulates the lower extremity kinematics of gait. This involves replacement of the typical crank link with a modified Cardan gear system. Simulations of typical rear-drive (crank-rocker) and front-drive (crank-slider) elliptical designs validate the improvement in lower limb hip and knee kinematics using this approach, suggesting that assistive elliptical rehabilitation systems can be more optimally designed to promote normal lower extremity gait kinematics compared to currently available devices.
Maximizing Coverage for Mobile Robots While Conserving Energy
Authors: Broderick John , Tilbury Dawn , Atkins Ella
Published: September 2013

This paper presents a method to compare area coverage paths in the context of energy efficiency. We examine cover-age paths created from the Boustrophedon Decomposition and Spanning Tree methods in an optimal control setting. Our cost function weights the force inputs to drive the robot and the currently uncovered region. We derive an optimal traversal of the path in a point-to-point manner. In particular, we introduce a meas function that represents the percentage of the area that is still to be visited. The effect of meas on the optimal traversal is derived. Trade-offs between area covered versus the time and energy required are presented. A simple trajectory modification allows the vehicle to continue moving through a turn to reduce energy consumption.
Numerical and Experimental Investigation of a New Nonlinear Energy Sink for Passive Shock Mitigation
Authors: AL-Shudeifat Mohammad A. , Wierschem Nicholas , Vakakis Alexander F. , Bergman Lawrence A. , Spencer Billie F.
Published: September 2013

A new device functioning as an efficient nonlinear energy sink (NES) is explored here. The device consists of a mass coupled to a two-story linear test structure through a single-sided vibro-impact (VI) nonlinearity in one direction and a weak linear spring in both directions. This design is found to be more efficient for passive targeted energy transfer (TET) than existing NESs. It absorbs and rapidly dissipates a significant amount of the impulsive energy induced in the linear structure. In addition, some of this initial energy is pumped to higher modes of the structure and efficiently dissipated there. The numerical results have verified that the proposed single-sided VI NES maintains high level of performance over a broad range of high input energies. It performs near to its optimum even for severe induced shocks. Moreover, the numerical results have been experimentally verified; good agreement between numerical predictions and experimental findings was observed.
Lighting Optimization for Sustainable Building Design Considering User Productivity
Authors: Piacenza Joseph R. , Tumer Irem Y. , Hoyle Christopher
Published: September 2013

User productivity is a key component of an integrated sustainable building design framework, as a consideration in addition to operating and construction costs associated with sustainable building practices. Research has shown that employee productivity increases as visible light levels rise in the workplace. Incorporating efficient lighting systems into sustainable building techniques can potentially increase user productivity while reducing electricity costs. This paper presents a single criterion approach that captures the trade-offs between costs, users, and current building standards. A model has been created to explore the feasible design space of a commercial workspace by populating a repository of both active and passive lighting components that can be accessed to generate various lighting designs. A genetic algorithm is used to optimize potential lighting choices in a given workspace, and allows the designer to explore Pareto optimal productivity solutions that best fit the desired application. The result is an optimal solution for a given workspace lighting configuration that captures user productivity while minimizing operating costs.
Design and Quaternion-Based Attitude Control of the Omnicopter MAV Using Feedback Linearization
Authors: Long Yangbo , Lyttle Sean , Pagano Nicholas , Cappelleri David J.
Published: September 2013

In this paper, we present the design of the Omnicopter, a micro aerial vehicle (MAV) with two central counter-rotating coaxial propellers for thrust and yaw control and three perimeter-mounted variable angle ducted fans to control roll and pitch. First, a dynamic model of the robot is established using the Euler-Lagrange formalism. Next, we focus on the attitude control for a special operating case of the Omnicopter with fixed vertical positions of the surrounding ducted fans. A nonlinear model is represented in state space using the quaternion and angular velocity as state variables, which simplifies the system dynamics. Based on this model, a feedback linearization controller is developed, which renders the system linear and controllable from an input-output point of view. The zero dynamics problem is also analyzed. Finally, simulations are carried out and the results illustrate that the attitude stabilization task for the Omnicopter is achieved.
Identifying Key Product Attributes and Their Importance Levels From Online Customer Reviews
Authors: Rai Rahul
Published: September 2013

Identifying customer needs and preferences is one of the most important tasks in design process. Typically, a variation of interview based approaches is used to conduct need and preference analysis. In this paper, a new approach based on text mining online (internet based) customer reviews to supplement traditional methods of need and preference analysis is considered. The key idea underlying the proposed approach is to partition online customer generated product reviews into segments that evaluate the individual attributes of a product (e.g zoom capability and support of different image formats in a camcorder). Additionally, the proposed method also identifies the importance (ranking) that customers place on each product attributes. The method is demonstrated on 100 customer reviews submitted for camcorders on epinions.com over a two year period.
The KCLBOT: The Challenges of Stereo Vision for a Small Autonomous Mobile Robot
Authors: Georgiou Evangelos , Dai Jian S. , Luck Michael
Published: September 2013

In small mobile robot research, autonomous platforms are severely constrained in navigation environments by the limitations of accurate sensory data to preform critical path planning, obstacle avoidance and self-localization tasks. The motivation for this work is to enable small autonomous mobile robots with a local stereo vision system that will provide an accurate reconstruction of a navigation environment for critical navigation tasks. This paper presents the KCLBOT, which was developed in King’s College London’s Centre for Robotic Research and is a small autonomous mobile robot with a stereo vision system.
Pre-Life and End-of-Life Combined Profit Optimization With Predictive Product Lifecycle Design
Authors: Ma Jungmok , Kwak Minjung , Kim Harrison M.
Published: September 2013

The Predictive Product Lifecycle Design (PPLD) model that is proposed in this paper enables a company to optimize its product lifecycle design strategy by considering pre-life and end-of-life at the initial design stage. By combining lifecycle design and predictive trend mining technique, the PPLD model can reflect both new and remanufactured product market demands, capture hidden and upcoming trends, and finally provide an optimal lifecycle design strategy in order to maximize profit over the span of the whole lifecycle. The outcomes are lifecycle design strategies such as product design features, the need for buy-backs at the end of its life, and the quantity of products remanufacturing. The developed model is illustrated with an example of a cell phone lifecycle design. The result clearly shows the benefit of the model when compared to a traditional Pre-life design model. The benefit would be increased profitability, while saving more natural resources and reducing wastes for manufacturers own purposes.
An Ensemble Approach for Robust Data-Driven Prognostics
Authors: Hu Chao , Youn Byeng D. , Wang Pingfeng , Yoon Joung Taek
Published: September 2013

Prognostics aims at determining whether a failure of an engineered system (e.g., a nuclear power plant) is impending and estimating the remaining useful life (RUL) before the failure occurs. The traditional data-driven prognostic approach involves the following three steps: (Step 1) construct multiple candidate algorithms using a training data set; (Step 2) evaluate their respective performance using a testing data set; and (Step 3) select the one with the best performance while discarding all the others. There are three main challenges in the traditional data-driven prognostic approach: (i) lack of robustness in the selected standalone algorithm; (ii) waste of the resources for constructing the algorithms that are discarded; and (iii) demand for the testing data in addition to the training data. To address these challenges, this paper proposes an ensemble approach for data-driven prognostics. This approach combines multiple member algorithms with a weighted-sum formulation where the weights are estimated by using one of the three weighting schemes, namely the accuracy-based weighting, diversity-based weighting and optimization-based weighting. In order to estimate the prediction error required by the accuracy- and optimization-based weighting schemes, we propose the use of the k-fold cross validation (CV) as a robust error estimator. The performance of the proposed ensemble approach is verified with three engineering case studies. It can be seen from all the case studies that the ensemble approach achieves better accuracy in RUL predictions compared to any sole algorithm when the member algorithms with good diversity show comparable prediction accuracy.
Vibration Analysis of Non-Pneumatic Tires With Hexagonal Lattice Spokes
Authors: Lee Chihun , Ju Jaehyung , Kim Doo-Man
Published: September 2013

With an increased interest in a non-pneumatic tire (NPT) and its possible performance on safety in driving and low rolling resistance, extensive research on mechanical properties including dynamic characteristics are required to explore for the commercialization of NPTs. In this study, we explore the dynamic characteristics of NPTs with flexible hexagonal lattice spokes. A steady state vibration characteristic of NPTs is investigated with a series of load carrying capability and rolling speed for two hexagonal spokes using a commercial finite element code, ABAQUS. The obtained vibration characteristics are compared with those of conventional pneumatic tires, which are available in the literature.
To Extend, or to Shorten: Optimal Lifetime Planning
Authors: Kwak Minjung , Kim Harrison M.
Published: September 2013

Extending the life of a product through remanufacturing or refurbishing is generally regarded as being “greener” than new production, as it avoids the resource consumption and waste generation associated with the new production; however, when considering improved performance of new products, extending the lifetime of less efficient, less productive old products may not always be greener than new production. Shortening the product’s life by early replacement with a newer, more efficient product can be a better option, as “Cash-for-Clunker” programs have claimed. This paper presents a generic model to decide optimal lifetime strategy for a product. Three different lifetime strategies—to maintain, to extend, and to shorten the current lifetime—are compared from an environmental perspective, for a given time horizon. The average environmental impact per unit production is used as the basis for a fair comparison. Applied with an optimization technique, the model can also identify the optimal lifetime length of a product. To illustrate, the developed model is applied to an example of complex heavy-duty, off-road equipment.
Efficient Sampling Methods for Tradeoff Studies Under Uncertainty
Authors: Bily Christopher S. , Malak Richard J.
Published: September 2013

Tradeoff studies help designers better understand how different design considerations relate to one another and to make decisions. Generally a tradeoff study involves a systematic multi-criteria evaluation of various alternatives for a particular system or subsystem. After evaluating these alternatives, designers eliminate those that perform poorly using the Pareto dominance criterion and explore more carefully those that remain.

An analogous procedure is possible when design criteria are uncertain. This approach is based on stochastic dominance principles that involve comparisons of probability distributions defined in the design criteria space. Although this is well-founded mathematically, the procedure can be computationally expensive because it typically entails a sampling-based uncertainty propagation method (e.g. Monte Carlo or quasi-Monte Carlo methods) for each alternative being considered.

In this paper we describe a statistically sound method which allows designers to sample the minimum number of samples necessary to eliminate dominated design alternatives under uncertainty. Dominance is evaluated using the appropriate hypothesis testing with specified confidence for a small sample, and the sample incrementally increased until dominance conditions can be determined. The method is demonstrated in the context of a tradeoff study for an automobile transmission.
Sustainable Product Family Planning Based on Product Life Cycle Simulation
Authors: Tao Jing , Yu Suiran
Published: September 2013

Product variety and improvements are the most important issues of today’s product development. Product family engineering is considered to be an effective approach to create new products that apply variability with decreased costs and time. However, given the environmental considerations, this study proposed sustainable product family planning which is a systematic design framework of product function; structure and lifecycle options (i.e. reduce, reuse and recycle). First, relationships between the diverse customer needs, product’s technical attributes and physical architecture are analyzed. Based on the analysis, certain product family plan including a product model change plan, a general product structure model, technical specifications and lifecycle options of each product in the family are established. A life cycle simulation tool is then developed for 1) easy building of various production strategies, product use scenarios and market competition cases, etc.; and 2) environmental and economic evaluations of the product family plan. A case study of personal computers (PCs) product family planning demonstrates an implementation of the proposed methods.
Numerical Solutions of Polynomial Equations for the Eight-Position Synthesis of the Cylindrical-Spherical Dyad
Authors: Huang Chintien , Hung Chenning , Tien Kuenming
Published: September 2013

This paper investigates the numerical solutions of equations for the eight-position rigid-body guidance of the cylindrical-spherical (C-S) dyad. We seek to determine the number of finite solutions by using the numerical continuation method. We derive the design equations using the geometric constraints of the C-S dyad and obtain seven quartic polynomial equations and one quadratic equation. We then solve the system of equations by using the software package Bertini. After examining various specifications, including those with random complex numbers, we conclude that there are 804 finite solutions of the C-S dyad for guiding a body through eight prescribed positions. When designing spatial dyads for rigid-body guidance, the C-S dyad is one of the four dyads that result in systems of equal numbers of equations and unknowns if the maximum number of allowable positions is specified. The numbers of finite solutions in the syntheses of the other three dyads have been obtained previously, and this paper provides the computational kinematic result of the last unsolved problem, the eight-position synthesis of the C-S dyad.
Training of Spatial Ability on Engineering Students Through a Remedial Course Based on Augmented Reality
Authors: Martín-Gutiérrez Jorge , Roca González Cristina , García Domínguez Melchor
Published: September 2013

This paper presents the results of a study designed to evaluate the effect of attending an intensive remedial course based on desktop augmented reality exercises to improve the spatial ability of freshman engineering students. Many of these students have problems in managing visual information or in creating mental models of objects represented by their orthographic projections. The study reports about research on comparison tests about the spatial skills of engineering students from two Spanish universities before and after performing a specific training for improving these abilities. The training was completed by 66 students as participants, considering a control group composed of 25 students from both universities. Results show that students from both universities improve their spatial ability and there is no statistical significance between students from both universities, neither before nor after training, so we may conclude that training’s effect on both universities is analogue.
Type Synthesis of Uncoupled 2T2R Parallel Manipulators
Authors: Zhang Yanbin , Ting Kwun-lon
Published: September 2013

This paper presents a simple and systematic method for type synthesis of four-degree-of-freedom uncoupled parallel manipulators with two-translational and two-rotational (2T2R) motion components. Based on the concept of hybrid manipulator, one uncoupled 2T2R hybrid manipulator, which is composed of one full-isotropic planar 2T1R parallel manipulator and one revolute joint in serial assembly, is designed first. Then the structure synthesis of the fourth leg of 2T2R parallel manipulator is performed in terms of the reciprocal screw theory. Finally, the type synthesis of uncoupled 2T2R parallel manipulators is realized by combining the uncoupled 2T2R hybrid manipulator and one of the synthesized fourth legs. The Jacobian of the uncoupled 2T2R parallel manipulator is a 4×4 diagonal matrix. Therefore, there exists a one-to-one correspondence between the input velocity space of the actuated joints and the output velocity space of the moving platform. Moreover, both the control design and the path planning of these proposed manipulators are very simple.
Combining Variation Simulation With Thermal Expansion for Geometry Assurance
Authors: Lorin Samuel , Lindkvist Lars , Söderberg Rikard , Sandboge Robert
Published: September 2013

In every set of assembled products there are geometrical variation and deviations from nominal dimensions. This can lead to products that are difficult to assemble or products not fulfilling functional or aesthetical requirements. In several industries variation simulation is used to predict assembly variation in the development phase. This analysis is usually done under the condition of room temperature only. However, for some materials, such as plastics, the thermal expansion can be significant in the intended environmental span of the product. In an assembly, this can lead to thermal stresses and parts that will deform. To avoid this problem, locating schemes need to be designed to allow for the right behavior while exposed to varying temperatures. In this work the effect of thermal expansion is studied in the context of variation simulation. A virtual tool for this end is also presented. An example from the automotive industry is used where the combined effect of thermal expansion and assembly variation is analyzed. It is shown that it may not be sufficient to simply add the result from thermal analysis to assembly variation. Hence, to assure the geometrical and functional quality of assembled products, during its use, variation simulations need to be combined with thermal stresses.
Rolling Condition and Gyroscopic Moments in Curve Negotiations
Authors: Shabana Ahmed A. , Hamper Martin B. , O’Shea James J.
Published: September 2013

In vehicle system dynamics, the effect of the gyroscopic moments can be significant during curve negotiations. The absolute angular velocity of the body can be expressed as the sum of two vectors; one vector is due to the curvature of the curve, while the second vector is due to the rate of changes of the angles that define the orientation of the body with respect to a coordinate system that follows the body motion. In this paper, the configuration of the body in the global coordinate system is defined using the trajectory coordinates in order to examine the effect of the gyroscopic moments in the case of curve negotiations. These coordinates consist of arc length, two relative translations and three relative angles. The relative translations and relative angles are defined with respect to a trajectory coordinate system that follows the motion of the body on the curve. It is shown that when the yaw and roll angles relative to the trajectory coordinate system are constrained and the motion is predominantly rolling, the effect of the gyroscopic moment on the motion becomes negligible, and in the case of pure rolling and zero yaw and roll angles, the generalized gyroscopic moment associated with the system degrees of freedom becomes identically zero. The analysis presented in this investigation sheds light on the danger of using derailment criteria that are not obtained using laws of motion, and therefore, such criteria should not be used in judging the stability of railroad vehicle systems. Furthermore, The analysis presented in this paper shows that the roll moment which can have a significant effect on the wheel/rail contact forces depends on the forward velocity in the case of curve negotiations. For this reason, roller rigs that do not allow for the wheelset forward velocity cannot capture these moment components, and therefore, cannot be used in the analysis of curve negotiations. A model of a suspended railroad wheelset is used in this investigation to study the gyroscopic effect during curve negotiations.
Wind Turbine Blade Design and Analysis With Tubercle Technology
Authors: Kumar Sourabh , Amano R. S.
Published: September 2013

The objective of this project is to construct a CAD model for tubercle wind turbine. Once the model is developed a complete CFD analysis of the flow pattern around the wind turbine will be carried out. The main objective of the study is to analyze and compare the performance of the tubercle wind turbine with the usual wind turbine. The power developed by both the turbine blades can be compared to support the use of tubercle. The tubercles are very effective for increasing the lift without stalling. The main objective of this project is to study the aerodynamic advantages of tubercle turbine blade. The effort will be to compare the obtained results with the straight blade of the same airfoil. This will provide insight into the advantages of using the tubercle blade. This technology being new the study is done numerically to study the overall effect of the tubercle.
Sampling-Based RBDO Using Probabilistic Sensitivity Analysis and Virtual Support Vector Machine
Authors: Song Hyeongjin , Choi K. K. , Lee Ikjin , Zhao Liang , Lamb David
Published: September 2013

In this paper, a sampling-based RBDO method using a classification method is presented. The probabilistic sensitivity analysis is used to compute sensitivities of probabilistic constraints with respect to random variables. Since the probabilistic sensitivity analysis requires only the limit state function, and not the response surface or sensitivity of the response, an efficient classification method can be used for a sampling-based RBDO. The proposed virtual support vector machine (VSVM), which is a classification method, is a support vector machine (SVM) with virtual samples. By introducing virtual samples, VSVM overcomes the deficiency in existing SVM that uses only classification information as their input. In this paper, the universal Kriging method is used to obtain locations of virtual samples to improve the accuracy of the limit state function for highly nonlinear problems. A sequential sampling strategy effectively inserts new samples near the limit state function. In sampling-based RBDO, Monte Carlo simulation (MCS) is used for the reliability analysis and probabilistic sensitivity analysis. Since SVM is an explicit classification method, unlike implicit methods, computational cost for evaluating a large number of MCS samples can be significantly reduced. Several efficiency strategies, such as the hyper-spherical local window for generation of the limit state function and the Transformations/Gibbs sampling method to generate uniform samples in the hyper-sphere, are also applied. Examples show that the proposed sampling-based RBDO using VSVM yields better efficiency in terms of the number of required samples and the computational cost for evaluating MCS samples while maintaining accuracy similar to that of sampling-based RBDO using the implicit dynamic Kriging (D-Kriging) method.
Automatic Extraction of Causally Related Functions From Natural-Language Text for Biomimetic Design
Authors: Cheong Hyunmin , Shu L. H.
Published: September 2013

Identifying relevant analogies from biology is a significant challenge in biomimetic design. Our natural-language approach addresses this challenge by developing techniques to search biological information in natural-language format, such as books or papers. This paper presents the application of natural-language processing techniques, such as part-of-speech tags, typed-dependency parsing, and syntactic patterns, to automatically extract and categorize causally related functions from text with biological information. Causally related functions, which specify how one action is enabled by another action, are considered important for both knowledge representation used to model biological information and analogical transfer of biological information performed by designers. An extraction algorithm was developed and scored F-measures of 0.78–0.85 in an initial development test. Because this research approach uses inexpensive and domain-independent techniques, the extraction algorithm has the potential to automatically identify patterns of causally related functions from a large amount of text that contains either biological or design information.
Filling N-Sided Holes Using Trimmed B-Spline Surfaces
Authors: Liu Xiaodong
Published: September 2013

Using one single trimmed B-Spline surface to fill an n-sided hole is a much desired operation in CAD, but few papers have addressed this issue. The paper presents the method of using trimmed B-Spline surfaces to fill n-sided holes based on energy minimization or variational technique. The method is efficient and robust, and takes less than one second to fill n-sided holes with high quality B-Spline surfaces under complex constraints.

As the foundation of filling n-sided holes, some key issues on variational B-Spline technique are also discussed. The variational technique discussed is significantly much more efficient and powerful than previous research, and the result is very accurate to satisfy CAD systems’ high-precision requirements. We demonstrate that, without any pre-calculation, the discussed technique is efficient enough to solve a B-Spline surface with up to 20,000 control points in real time while satisfying an arbitrary combination of point and curve constraints.
A Bisociative Design Framework for Knowledge Discovery Across Seemingly Unrelated Product Domains
Authors: Tucker Conrad S. , Kang Sung Woo
Published: September 2013

The Bisociative Design framework proposed in this work aims to quantify hidden, previously unknown design synergies/insights across seemingly unrelated product domains. Despite the overabundance of data characterizing the digital age, designers still face tremendous challenges in transforming data into knowledge throughout the design processes. Data driven methodologies play a significant role in the product design process ranging from customer preference modeling to detailed engineering design. Existing data driven methodologies employed in the design community generate mathematical models based on data relating to a specific domain and are therefore constrained in their ability to discover novel design insights beyond the domain itself (I.e., cross domain knowledge).

The Bisociative Design framework proposed in this work overcomes the limitations of current data driven design methodologies by decomposing design artifacts into form patterns, function patterns and behavior patterns and then evaluating potential cross-domain design insights through a proposed multidimensional Bisociative Design metric.

A hybrid marine model involving multiple domains (capable of flight and marine navigation) is used as a case study to demonstrate the proposed Bisociative Design framework and explain how associations and novel design models can be generated through the discovery of hidden, previously unknown patterns across multiple, unrelated domains.
Workspace Comparison Between 3-PRR and 3-RPR Micro-Manipulator
Authors: Dong Yi , Gao Feng , Yue Yi , Feng Jin
Published: September 2013

This paper presents two compliant micro-manipulators with different structures. One uses 3-PRR mechanism while the other one adopts 3-RPR mechanism. Both of the two micro-manipulators have two translational degrees of freedom (DOF) and one rotational DOF. But the properties, such as workspace, of the two micro-manipulators are not the same. In this paper, the workspaces are studied and compared. First, the structural differences are presented. Then, the stiffness derivations of the two micro-manipulators are given and the workspaces are calculated considering the properties of piezoelectric (PZT) actuators. Finally the finite element analysis and prototype experiments are performed to validate the obtained results.
A Nested Extreme Response Surface Approach for RBDO With Time-Dependent Probabilistic Constraints
Authors: Wang Zequn , Wang Pingfeng
Published: September 2013

A primary concern in practical engineering design is ensuring high system reliability throughout a product life-cycle subject to time-variant operating conditions and component deteriorations. Thus, the capability to deal with time-dependent probabilistic constraints in reliability-based design optimization is of vital importance in practical engineering design applications. This paper presents a nested extreme response surface (NERS) approach to efficiently carry out time-dependent reliability analysis and determine the optimal designs. The NERS employs kriging model to build a nested response surface of time corresponding to the extreme value of the limit state function. The efficient global optimization technique is integrated with the NERS to extract the extreme time responses of the limit state function for any given system design. An adaptive response prediction and model maturation mechanism is developed based on mean square error (MSE) to concurrently improve the accuracy and computational efficiency of the proposed approach. With the nested response surface of time, the time-dependent reliability analysis can be converted into the time-independent reliability analysis and existing advanced reliability analysis and design methods can be used. The NERS is integrated with RBDO for the design of engineered systems with time-dependent probabilistic constraints. Two case studies are used to demonstrate the efficacy of the proposed NERS approach.