bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanism Branches, Turning Curves, and Critical Points
Authors: Myszka David H. , Murray Andrew P. , Wampler Charles W.
Published: September 2013

This paper considers single-degree-of-freedom, closed-loop linkages with a designated input angle and one design parameter. For a fixed value of the design parameter, a linkage has turning points (dead-input singularities), which break the motion curve into branches such that the motion along each branch can be driven monotonically from the input. As the design parameter changes, the number of branches and their connections, in short the topology of the motion curve, may change at certain critical points. As the design parameter changes, the turning points sweep out a curve we call the “turning curve,” and the critical points are the singularities in this curve with respect to the design parameter. The critical points have succinct geometric interpretations as transition linkages. We present a general method to compute the turning curve and its critical points. As an example, the method is used on a Stephenson II linkage. Additionally, the Stephenson III linkage is revisited where the input angle is able to rotate more than one revolution between singularities. This characteristic is associated with cusps on the turning point curve.
Holistic Approach to Green Buildings From Construction Material to Services
Authors: Khalil Essam E.
Published: September 2013

Attempts to adequately design an optimum HVAC airside system that furnishes comfort and air quality in the air-conditioned spaces with efficient energy consumption represent a great challenge. Air conditioning identifies the conditioning of air for maintaining specific conditions of temperature, humidity, and dust level inside an enclosed space. The conditions to be maintained are dictated by the need for which the conditioned space is intended and comfort of users. So, the air conditioning embraces more than cooling or heating. The comfort air conditioning is defined as “the process of treating air to control simultaneously its temperature, humidity, cleanliness, and distribution to meet the comfort requirements of the occupants of the conditioned space”. Air conditioning, therefore, includes the entire heat exchange operation as well as the regulation of velocity, thermal radiation and quality of air, as well as the removal of foreign particles and vapors. Achieving occupant comfort and health is the result of a collaborative effort of environmental conditions, such as: Indoor air temperature; relative humidity; airflow velocity; pressure relationship; air movement efficiency; Contaminant concentration; Illumination and visual comfort; and sound and noise; and other factors. In the holistic approach, the totality of the effects of the heat sink and sources in the building and the technical building systems that are recoverable for space conditioning, are typically considered in the calculation of the thermal energy needs. As the technical building thermal systems losses depend on the energy input, which itself depends on the recovered system thermal sources, iteration might be required. The present paper reviews the status quo and critically analyses the appropriate approaches to sustainability.
Design of Energy Efficient Commercial Buildings in Developing Countries
Authors: Khalil Essam E.
Published: September 2013

Energy Performance of Buildings should include a general framework for the calculation of energy performance and building categories together with thermal characteristics of building, air conditioning, ventilation, lighting and appliances aspects considered. These include Active solar systems contribution to domestic water heating based on renewable energy sources, CPH production and District cooling systems. This paper reviews the energy sources available in Egypt, their distribution and utilization in commercial sectors. The paper demonstrates the importance of incorporating an energy performance directive as a Standard in our region such a goal will aid energy savings in large buildings and set regulations to energy efficient designs that are based on Standard calculation methods. The proposed Standard would be largely based on International Standards and appropriately modified to suit local practices. The target is to develop standardized tools for the calculation of the energy performance of buildings, with defined system boundaries for the different building categories and different cooling/heating systems. The present work is to provide transparent information regarding output data (reference values, benchmarks, etc.) and to define comparable energy related key values (kWh/m2, kWh per person, kWh per apartment, kWh per produced unit etc.). Proposals to develop a common procedure for an “energy performance certificate” and CO2 emissions are given.
Numerical Computations of Flow Regimes in Enclosed Spaces
Authors: El Degwy Ahmed E. A. , Morkos Sami M. , Sabry Ashraf S. , Khalil Essam E.
Published: September 2013

This paper is devoted to critically analyse the simulation validity of flow regimes in large rooms and enclosed spaces using commercially available computational fluid dynamics code. This assessment is carried out through detailed comparisons between previous experimental and numerical data as well as present numerical data. Governing equations of mass, momentum, energy and species are solved numerically to predict the air flow patterns and thermal behaviour in rooms and healthcare facilities. The present paper is divided to several sections that review the previous research in open literature and briefly describe the governing equations, boundary and inlet conditions, as well as modelling assumptions. The turbulence characteristics of the flow is represented through the two equation turbulence model that solves the transport equations for the kinetic energy of turbulence k and its dissipation rate ε in full three dimensional domain under steady state conditions. Energy efficiency improvement in air-conditioned buildings applications was found to depend mainly on the design configurations and operating parameters. The room airside design is one of the essential factors that strongly influence the HVAC airflow pattern and consequently the air quality and comfort inside special rooms. After comparing measured and predicted flow regimes in different spaces, a brief summary of conclusions with some recommendations to facilitate the development of optimum energy efficient design are presented.
Optimization of Wind Farm Layout and Wind Turbine Geometry Using a Multi-Level Extended Pattern Search Algorithm That Accounts for Variation in Wind Shear Profile Shape
Authors: DuPont Bryony L. , Cagan Jonathan , Moriarty Patrick
Published: September 2013

This paper presents a multi-level Extended Pattern Search algorithm (EPS) to optimize both the local positioning and geometry of wind turbines on a wind farm. Additionally, this work begins to draw attention to the effects of atmospheric stability on wind farm power development. The wind farm layout optimization problem involves optimizing the local position and size of wind turbines such that the aerodynamic effects of upstream turbines are reduced, thereby increasing the effective wind speed at each turbine, allowing it to develop more power. The extended pattern search, employed within a multi-agent system architecture, uses a deterministic approach with stochastic extensions to avoid local minima and converge on superior solutions compared to other algorithms. The EPS presented herein is used in an iterative, hierarchical scheme — an overarching pattern search determines individual turbine positioning, then a sub-level EPS determines the optimal hub height and rotor for each turbine, and the entire search is iterated. This work also explores the wind shear profile shape to better estimate the effects of changes in the atmosphere, specifically the changes in wind speed with respect to height on the total power development of the farm. This consideration shows how even slight changes in time of day, hub height, and farm location can impact the resulting power. The objective function used in this work is the maximization of profit. The farm installation cost is estimated using a data surface derived from the National Renewable Energy Laboratory (NREL) JEDI wind model. Two wind cases are considered: a test case utilizing constant wind speed and unidirectional wind, and a more realistic wind case that considers three discrete wind speeds and varying wind directions, each of which is represented by a fraction of occurrence. Resulting layouts indicate the effects of more accurate cost and power modeling, partial wake interaction, as well as the differences attributed to including and neglecting the effects of atmospheric stability on the wind shear profile shape.
Design of Complex Nano-Scale Systems Using Multi-Agent Simulations and Structure-Behavior-Function Representations
Authors: Egan Paul F. , Cagan Jonathan , Schunn Christian , LeDuc Philip R.
Published: September 2013

Recent trends in technology are challenging engineers to configure products at ever smaller scales. At the nano-scale, biological protein machines are commonly chosen as a power-source for a broad-range of nano-devices. This paper explores the challenges in designing these and similar systems, such as improving the emergent system performance that arises from the interactions of many stochastic components.

We develop a domain-independent methodology, using multi-agent simulations as a means of modeling and predicting emergent system behavior across scales and structure-behavior-function representations for understanding and navigating the resulting design space. This methodology is validated with an application of synthetic myosin motor design at the nanoscale, with simulation results aligning well with the macroscopic performance of myosin-powered muscular contractions.

The multi-agent simulation is implemented with myosins modeled as agents, allowing for the virtual design and experimentation of synthetic myosins with altered structures and mechanochemical behaviors. Four myosin populations are designed and simulated, with their emergent system performance determined by aggregating the contributions of each myosin agent over time.

Although the multi-agent simulation successfully recreates the emergent behaviors of the myosins, it is difficult to draw conclusions about how each structural variation influences aggregate performance. SBF representations of the system are then developed to describe how the aggregate performance of the system is explainable in terms of myosin behaviors, which map directly to altered myosin structures. It is then demonstrated how an engineer may utilize these representations and experimental results to reason about, and configure a myosin system with optimal performance.

The methodology is domain-independent, ensuring its extendibility to similar complex systems while aiding a designer in simplifying a complex physical phenomenon to a design space consisting of only a few critical parameters. The methodology is particularly suited for complex systems with many parts operating stochastically across scales, and should prove invaluable for engineers facing the challenges of biological nanoscale design, where designs with unique properties require novel approaches or useful configurations in nature await discovery.
Dynamics and Control of the Robotic Lumbar Spine (RLS)
Authors: Karadogan Ernur , Williams Robert L.
Published: September 2013

This paper presents the dynamics and nonlinear control of the Robotic Lumbar Spine (RLS). The RLS is a 15 degree-of-freedom, fully cable-actuated robotic lumbar spine which can mimic in vivo human lumbar spine movements to provide better hands-on training for medical students. The current design includes five active lumbar vertebrae and the sacrum, with dimensions of an average adult human spine. It is actuated by 20 cables connected to electric motors. Every vertebra is connected to the neighboring vertebrae by spherical joints. Medical schools can benefit from a tool, system, or method that will help instructors train students and assess their tactile proficiency throughout their education. The robotic lumbar spine has the potential to satisfy these needs in palpatory diagnosis. Additionally, a new approach to solve for positive and nonzero cable tensions that are also continuous in time is introduced.
Solitary Waves in 1:N Dimer Chains
Authors: Jayaprakash K. R. , Vakakis Alexander F. , Starosvetsky Yuli
Published: September 2013

In the present work we report the discovery of new families of solitary waves in a 1:N (N>1) granular dimers (a heavy bead followed and preceded by N light beads) wherein the Hertzian interaction law governs the interaction between spherical beads. We consider the dimer chain with zero precompression. The dynamics of such a dimer chain is governed by two system parameters, the stiffness ratio and the mass ratio between the light and the heavy beads. In particular we study in detail the solitary waves in 1:2 dimer chains [11]. The solitary waves in a 1:2 dimer are contrastingly different from that in a homogeneous chain and 1:1 dimer chain. Solitary waves realized in homogeneous and 1:1 dimer chains possess symmetric velocity waveforms. In contrast, in a 1:2 dimer chain we realize solitary waves that have symmetric velocity waveforms on the heavy beads, whereas that on the light beads is non-symmetric. The existence of families of solitary waves in these systems is attributed to the dynamical phenomenon to ‘anti-resonance’. This leads to the complete elimination of radiating waves in the trail of the propagating pulse. Anti-resonances are associated with certain symmetries of the velocity waveforms of the beads of the dimer. We conjecture that a countable infinity of family of solitary waves can be realized in 1:2 dimer chains. Interestingly, solitary waves in a general 1:N (N>2) dimer chain are far more difficult to realize. For the case of 1:2 dimers, we can vary the two parameters to satisfy conditions such that the oscillatory tails in the trail of the primary pulse of the two light beads decay to zero. In contrast, for a 1:N (N>2) dimer chain, we have the same two parameters but need to satisfy the decaying conditions on N light beads simultaneously. This leads to a mathematically ill-posed problem and as such rigorously no solitary waves can be realized in general.
Comparing the Contribution of the Group to the Initial Idea in Progressive Idea Generation
Authors: Blair Bryan M. , Hölttä-Otto Katja
Published: September 2013

Successful Idea Generation (IG) is more likely to lead to original and innovative products. It is usually recommended that idea generation is done in groups. Specifically, progressive idea generation methods, such as 6-3-5/C-Sketch, have been developed to gain from the benefits of group based ideation while being less subject to the peer pressure of a typical brainstorming session, where people can call out ideas simultaneously. In this study, we investigate the contributions that the group makes to the initial ideas in such progressive idea generation.

Participants developed concepts for one of two products, namely alarm clocks or litter grabbers. Statistical analysis was used to compare the results of the initial ideas to the entire group for both products. Samples were rated at feature level using three metrics: originality, number of innovation characteristics hit, and feasibility.

Results indicate that, in general, the originality and innovativeness of the initial concepts is improved by the rest of the group members. Non-original initial ideas were improved in all four sample groups. Highly original initial ideas also were improved in most cases. Feasibility was generally lowered, but not with statistical significance. Results from the perspective of particular product feature and innovation characteristic categories were varied; some more popular than others.
Questioning the Impact of Personality on Design Outcomes: Should We Take It Into Account?
Authors: Okudan Gül E. , Schmidt Linda C. , Vargas Hernandez Noe , Jablokow Kathryn , Lin Chun-yu
Published: September 2013

To investigate the impact of personality factors on the novelty and variety of design outcomes, we conducted an experiment with 33 engineering students of various class standings. All students were enrolled in an introductory engineering design class and completed the same design task, improving the functionality of a traffic light while making sure that it runs sustainably. Our results indicate significant impact of two personality dimensions on design outcomes: openness and agreeableness. These results match findings in the literature that show significant impact of certain personality dimensions of individual scientists on creative problem solving outcomes. We argue that creative problem solving in the engineering domain can be different, as it might require a higher level of tactile thinking in comparison to science; thus, investigation of the impact of personality on creative outcomes was necessary. Accordingly, we recommend measuring and using the personality dimensions as co-variates in empirical observations of design outcomes.
CNT Cantilevers Under Soft AC Actuation of Frequency Near Half Natural Frequency for Bio-Sensing Applications
Authors: Caruntu Dumitru I. , Luo Le
Published: September 2013

This paper deals with electrostatically actuated Carbon Nano-Tubes (CNT) cantilevers for bio-sensing applications. Four forces act on the CNT cantilever, namely electrostatic, elastostatic, van der Waals, and damping. The van der Waals forces are significant for values of 50 nm or lower of the gap between the CNT and the ground plate. As both forces electrostatic and van der Waals are nonlinear, and the CNT electrostatic actuation is given by AC voltage, the CNT undergoes nonlinear parametric dynamics. The method of multiple scales (MMS) is used to investigate the system under soft excitations and/or weak nonlinearities. The frequency-amplitude and frequency-phase behavior are reported. The CNT bio-sensor is to be used for mass detection applications.
The Structure of Creative Design: What Problem Maps Can Tell Us About Problem Formulation and Creative Designers
Authors: Danielescu Andreea , Dinar Mahmoud , MacLellan Christopher , Shah Jami J. , Langley Pat
Published: September 2013

Problem formulation is an important part of the design process that has been largely underexplored. Similarly, the relationship between how designers formulate problems and creative outcome is not well understood. To shed light on what the process of problem formulation can tell us about creativity in design, we use the problem map model — a flexible, domain-independent ontology for modeling the design formulation process — to analyze protocols from eight expert designers. In this paper, we discuss the effectiveness of using problem maps for coding design protocols and what the problem map model can tell us about the protocols of designers. In this exploratory study, we use the problem map model to code and analyze the problem formulation stage of the design process.
Reduced Order Model of Electrostatically Actuated MEMS Resonators Resonance Near Half Natural Frequency
Authors: Caruntu Dumitru I. , Martinez Israel , Knecht Martin W.
Published: September 2013

This paper uses the Reduced Order Model (ROM) method to investigate the influence of nonlinearities from parametric electrostatic excitation due to soft AC voltage of frequency near half natural frequency of the MEMS cantilever resonator on its frequency response. Most of the analysis in literature investigates pull-in phenomenon, stability, amplitude–frequency relations, or finds time responses of such systems. In this work it is showed that the bifurcation points in the amplitude-frequency response occur at lower frequencies and amplitudes than predicted by the Method of Multiple Scales (MMS), a perturbation method. This result is extremely important for predicting pull-in phenomena. Also the ROM predicts pull-in instability for large initial amplitudes and AC frequencies less than half natural frequency of the resonator. MMS fails to predict this behavior. Increasing the damping and/or decreasing the voltage increases the frequency at which the system undergoes into a pull-in phenomenon.
Flow-Induced Deformations of a Compliant Insert in Channel Flow: From Small to Large Amplitudes
Authors: Lai Lawrence S. H. , Lucey Anthony D. , Elliott Novak S. J.
Published: September 2013

In this paper we consider a fluid-conveying channel with a compliant insert undergoing large amplitude flow-induced deformations. The objective is to assess the suitability of an open source finite element library oomph-lib for modelling this system. The fundamental system is relevant to a host of applications in both engineered (e.g. flexible-pipes, membrane filters, and general aero-/hydro-elasticity) and biomechanical (e.g. blood flow, airway flow) systems. The structural model uses a geometrically nonlinear formulation of the solid mechanics. Viscous flow is modelled at Reynolds numbers producing unsteady laminar flow. We present a brief summary of previous component validations with oomph-lib. We then focus on the unsteady-state FSI validation by comparing with published results, obtained using different computational schemes. This is done for both small-amplitude and large-amplitude wall deformations. Finally, we look at some preliminary energetics analysis of the flexible wall. The validations demonstrate the suitability and versatility of oomph-lib as a modelling and predictive tool. The flexible wall energetics validation show the possibility of understanding system stability through analysis of the flexible wall and fluid energetics.
A Design Method Based on Ant Colony Optimization for Compliant Mechanisms: Introduction and Application to a Surgical Tool
Authors: Rubbert L. , Renaud P. , Gangloff J.
Published: September 2013

This paper presents a design method dedicated to compliant mechanisms, with emphasis on the use of ant colony optimization to determine the optimal geometry of a mechanism. Ant colony optimization is of particular interest because it does not need any fine tuning of its internal parameters. This robustness and the efficiency of the design method are assessed in the context of the design of a surgical tool. The method is then used to propose a new architecture for an active cardiac stabilizer with integrated actuation, contrary to existing architectures.
Disassembly Sequence Evaluation Using Graph Visualization and Immersive Computing Technologies
Authors: Berg Leif P. , Behdad Sara , Vance Judy M. , Thurston Deborah
Published: September 2013

With the goal of making product recovery economically viable, disassembly sequence planning and evaluation can be used to influence product design features early in the product design process. Several researchers have investigated using optimization methods to determine disassembly sequences. One of the difficulties with using this approach is that because of the unique aspects of product disassembly at the end of life, input parameters for the optimization algorithms are commonly unavailable or estimated under high uncertainty. In practice, design engineers explore disassembly sequencing using either CAD software or manipulation of physical prototypes. These approaches produce solutions, but only intuitive solutions are explored and more optimal solutions may exist. To support decision making early in the design process, the research presented in this paper combines these two approaches within an immersive computing technology (ICT) application to aid in early product design with the goal of designing products with consideration of product recovery, reuse and recycle.

The ICT application displays both 3D geometry of the product to be disassembled and an interactive graph visualization of the potential disassembly paths. The user can naturally interact with the geometric models and explore the potential paths indicated by the graph visualization. The optimal path can be indicated and the user can explore other potential paths. The result is an application that combines the strength of mathematical modeling with visualization and human interaction to provide an experience where the user can explore potential effects of design decisions. The initial application has been implemented in a 3 wall immersive projection environment and preliminary results show this approach proves to be an efficient method of evaluating and training potential disassembly sequences.
Using the Mass Ratio to Induce Band Gaps in a 1D Array of Nonlinearly Coupled Oscillators
Authors: Bernard Brian P. , Peyser Jeffrey W. , Mann Brian P. , Arnold David P.
Published: September 2013

A one dimensional system of nonlinearly coupled magnetic oscillators has been studied. After deriving the equations of motion for each oscillator, the system is linearized about a stable equilibrium and studied using an assumed solution form for a traveling wave. Wave propagation and attenuation regions are predicted by reducing the system of equations to a standard eigenvalue problem. Through evaluating these equations across the entire irreducible Brillouin zone, it is determined that when the masses of each oscillator are identical, the entire frequency range of the system is a propagation zone. By varying the masses comprising a unit cell, band gaps are observed. It is shown that the mass ratio can be used to guide both the size and location of these band gaps. Numerical simulations are performed to support our analytical findings.
Self-Assessment for Evaluating and Improving the Product Development Processes in SMEs
Authors: Bensiek Tobias , Kühn Arno , Gausemeier Jürgen , Grafe Michael
Published: September 2013

Effective and efficient processes characterize successful companies in mechanical engineering and related industrial sectors. Methods and tools of Virtual Prototyping and Simulation (VPS) become more and more accepted in these processes. The integration of these methods and tools into the processes and the PDM/PLM infrastructure of the company is a success factor in the development of complex technical systems. Especially small and medium sized enterprises (SMEs) often run isolated applications that are insufficiently integrated into the development process and the PDM/PLM infrastructure.

This paper introduces the VPS-Benchmark — an adaptable maturity model for performance evaluation and improvement in small and medium-sized enterprises (SMEs) with focus on VPS. By giving an overview on existing approaches for performance evaluation and improvement, we point out the demand for a new maturity approach meeting the requirements of SMEs. The new maturity model will then be introduced. After explaining the basic concept of the model, we describe its development and application. The model offers a systematic performance improvement by giving concrete measures. These measures are derived from the comparison of current performance and a company-specific target state. This individual target state is determined by the company-class. The whole approach is based on a software-supported questionnaire that allows for a self-assessment in SMEs.
The Discrete Topology Optimization of Compliant Mechanisms
Authors: Zhou Hong , Ayyalasomayajula Chandrasekhar M.
Published: September 2013

In the discrete topology optimization, material state is either solid or void and there is no topology uncertainty problem caused by intermediate material state. The outer corner cutting and inner corner filling strategy is introduced in this paper for the discrete topology optimization of compliant mechanisms. The design domain is discretized into quadrilateral design cells and every quadrilateral design cell is further subdivided into triangular analysis cells. All outer and inner corners are eliminated with the corner handling strategy. To make the designed compliant mechanisms safe, the local stress constraint is directly imposed on each triangular analysis cell. To circumvent the geometrical bias against the vertical design cells, the binary bit-array genetic algorithm is used to search for the optimal topology. Two topology optimization examples of compliant mechanisms are solved based on the proposed corner handling strategy and subdivision approach.
The Impact of Product Dissection Activities on the Novelty of Design Outcomes
Authors: Toh Christine A. , Miller Scarlett R. , Okudan Kremer Gül E.
Published: September 2013

This paper explores the effect of a product dissection activity on design novelty in engineering design. Novelty is an important aspect of design ideation effectiveness. Therefore, identifying the factors that influence novelty will expand the understanding of the design process, as well as improve design pedagogy. Previous studies have found that participation in product dissection activities positively impacted creativity, but did not study creativity in terms of novelty, making it unclear if product dissection activities will impact the novelty of generated designs. Furthermore, although product dissection has been studied in team environments, individual factors such as the personality traits of the team members was not explored for their effect on the exposure to the dissection activity, and hence the effect on the novelty of generated designs. Our empirical experimentation showed that extraverted participants had a higher level of exposure to the body design dissection activity and developed more novel ideas than those who were not extraverts. These results contribute to our understanding on how team-based dissection activities influence the novelty of generated designs in an engineering design setting.
Reliability Based Design Optimization Considering Future Redesign With Different Epistemic Uncertainty Treatments
Authors: Matsumura Taiki , Haftka Raphael T. , Sankar Bhavani V.
Published: September 2013

The design of engineering systems is often based on analysis models with substantial errors in predicting failures, that is epistemic uncertainty. The epistemic uncertainty is reduced by post design tests, and the safety of unsafe designs restored by redesign. When this process of design, test and redesign is to be based on probabilistic analysis, there is some controversy on whether uncertainty associated with variability (aleatory uncertainty) should be treated differently than the epistemic uncertainty. In this paper we compare several approaches to design and redesign and treatments of the epistemic uncertainties. These include safety factors, probabilistic approach disregarding redesign and regarding redesign, treating epistemic uncertainty and aleatory uncertainty the same, and more conservative treatment of the epistemic uncertainty. We demonstrate that the proposed approach can allow tradeoff of system performance against development cost (probability of redesign), while a standard reliability based design optimization, which does not take into account future redesign, provides only a single point on the tradeoff curve. We also show that the tradeoff can be achieved even with the traditional safety factor approach, without any probabilistic optimization. Furthermore, we investigate different treatments of epistemic error for probability of failure calculation. We find that it is possible to design to the 95th percentile of the probability of failure with modest mass penalty compared to treating epistemic and aleatory uncertainty alike.
A Systematic Method for Model Parameter Identification of Nonlinear Dynamics Systems Using Trajectory Pattern Method
Authors: Rastegar Jahangir , Feng Dake
Published: September 2013

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, 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 structure of the feedback error with feedforward signal calculated with the estimated model parameters will then be fixed, and its measurement can be used to systematically upgrade the model parameter estimation. The mathematical proof of convergence of the developed method and results of its implementation on a robot manipulator with highly non-linear dynamics are provided.
A Genetic Algorithm Approach for Technology Characterization
Authors: Galvan Edgar , Malak Richard
Published: September 2013

It is important for engineers to understand the capabilities and limitations of the technologies they consider for use in their systems. Several researchers have investigated approaches for modeling the capabilities of a technology with the aim of supporting the design process. In these works, the information about the physical form is typically abstracted away. However, the efficient generation of an accurate model of technical capabilities remains a challenge. Pareto frontier based methods are often used but yield results that are of limited use for subsequent decision making and analysis. Models based on parameterized Pareto frontiers—termed Technology Characterization Models (TCMs)—are much more reusable and composable. However, there exists no efficient technique for modeling the parameterized Pareto frontier. The contribution of this paper is a new algorithm for modeling the parameterized Pareto frontier to be used as a model of the characteristics of a technology. The proposed algorithm uses fundamental concepts from multiobjective genetic optimization and machine learning to generate a model of the technology frontier.
Modeling Slope Discontinuity of Large Size Wind-Turbine Blade Using Absolute Nodal Coordinate Formulation
Authors: Bayoumy Ahmed H. , Nada Ayman A. , Megahed Said M.
Published: September 2013

This paper describes the use of the Absolute Nodal Coordinate Formulation (ANCF) in modeling large-size wind turbine blades. An efficient procedure is developed for mapping NACA airfoil wind-turbine blades into ANCF thin plate models. The procedure concerns the wind turbine blade with non-uniform, twisted nature. As a result, the slope discontinuity problem arises and presents numerical errors in the dynamic simulation. This investigation illustrates a method for modeling slope discontinuity resulting from the variations of the cross sectional layouts across the blade. A method is developed and applied for the gradient-deficient thin plate element in order to account for structural discontinuity. The numerical results show a numerical convergence and satisfy the principle of work and energy in dynamics. The simulation results are compared with those obtained using ANSYS code with a good agreement.
Synthesizing the Compliant Microstructure of Thermally Actuated Materials Using Freedom, Actuation, and Constraint Topologies
Authors: Hopkins Jonathan B. , Lange Kyle J. , Spadaccini Christopher M.
Published: September 2013

The aim of this paper is to demonstrate how the principles of the Freedom, Actuation, and Constraint Topologies (FACT) synthesis approach may be applied to the design of compliant microstructural architectures that possess extreme or unusual thermal expansion properties (e.g., zero or large negative thermal expansion coefficients). FACT provides designers with a comprehensive library of geometric shapes, which may be used to visualize the regions wherein various microstructural elements can be placed for achieving desired bulk material properties. In this way, designers can rapidly consider and compare every microstructural concept that best satisfies the design requirements before selecting the final design. A screw-theory-based analytical tool is also provided in this paper to help designers calculate and optimize the thermal properties of microstructural concepts, which are generated using FACT. As a case study, this tool is used to calculate the negative thermal expansion coefficient of a microstructural architecture synthesized using FACT.
Stochastic Optimal Control of Linear Multi-Degree-of-Freedom Systems Under Nonstationary Random Excitations
Authors: Nkundineza Celestin , To Cho W. S.
Published: September 2013

Stochastic optimal control is an important area of research in engineering systems that undergo disturbances such as earthquake excitations and blast waves. Controlling states such as positions of different parts in these systems is critical in situations in which the system has to operate within limited range of its states. The present investigation is concerned with the application of the stochastic optimal control strategy developed by To (2010) and its implementation as well as providing computed results of linear systems under nonstationary random excitations. In the strategy the feedback matrix is designed based on the achievement of the objectives for individual states in the system through the application of the Lyapunov equation of the system. Every diagonal element in the gain or associated gain matrix is related to the corresponding states. The strategy is applied to two two-degree-of-freedom (dof) systems representing buildings under earthquake excitations. Optimally controlled nonstationary random displacements were obtained by the proposed method and presented in this paper. The computed results include the time-dependent elements of the associated gain matrix. Three-dimensional (3D) graphical representations of the optimally controlled largest peaks of mean squares of displacements and velocities against elements of the feedback gain matrix were included. The latter 3D presentations are important for the design engineer who needs to choose elements of the gain matrix in order to achieve a specific objective in certain states of the system.
Safety Design Evaluation of Motorcycle Helmet for Oblique Impact
Authors: Ebrahimi Iman , Golnaraghi Farid , Wang Gary , Madani Ali , Yin David , Lu Jun , Chor Alexandrea , Jelveh Combiz
Published: September 2013

In this work, safety of motorcycle helmet design is investigated by using standard oblique impact test method. First, testing procedure is explained and test rig mechanism is introduced. Next, standard impact tests are performed on helmets. Data are collected using a tri-axial linear accelerometer embedded inside the headform and a high speed camera for measuring rotational acceleration. Then, results are studied and compared to injurious limit for human head injury. It is shown that during an oblique impact rotational acceleration can easily surpass the safe limit while the linear acceleration is well below the safe limit.
Pattern Characterization in Acceleration Vector Fields Developed in Complex Beam Structures Subject to an Excitation Protocol by Impulsive Forces
Authors: Georgiou Ioannis T.
Published: September 2013

Presented are interesting results concerning aspects of the space-time characteristics of coherence patterns of ensembles of impulsive coupled acceleration signals developed in the complex domain of a physical multi-body flexible structure. A modal hammer is used to systematically pulse-interrogate the structure whereas a state of the art piezoelectric tri-axial accelerometer is used to collect at a point time series samples of coupled dynamics. We find the remarkable fact that collocated ensembles of signals of the acceleration vector field are underlain by strong spatio-temporal coherence which is robust under random experimental error introduced in the impulsive force protocol of interrogation. Coherence is characterized-identified optimally in terms of Proper Orthogonal Decomposition (POD) modes. The POD-identified space-time coherence structures, or patterns, feature an unparalleled classical modal-like characterization of coherence of collocated multi-dimensional information. The identified dominant POD spatio-temporal patterns have the space-time modulation characteristics of classical normal modes of vibration of three-dimensional coupled structural dynamics. Exploiting in full the transient dynamics and being model free, this test and evaluation modal-like identification technique can lead to a reliable certification procedure of multi-body flexible structural systems in critical applications.
Online Real-Time Monitoring System Through Using Adaptive Angular-Velocity VKF Order Tracking
Authors: Yeh Ting-Chi , Pan Min-Chun
Published: September 2013

When rotary machines are running, acousto-mechanical signals acquired from the machines are able to reveal their operation status and machine conditions. Mechanical systems under periodic loading due to rotary operation usually respond in measurements with a superposition of sinusoids whose frequencies are integer (or fractional integer) multiples of the reference shaft speed. In this study we built an online real-time machine condition monitoring system based on the adaptive angular-velocity Vold-Kalman filtering order tracking (AV2KF_OT) algorithm, which was implemented through a DSP chip module and a user interface coded by the LabVIEW®.

This paper briefly introduces the theoretical derivation and numerical implementation of computation scheme. Experimental works justify the effectiveness of applying the developed online real-time condition monitoring system. They are the detection of startup on the fluid-induced instability, whirl, performed by using a journal-bearing rotor test rig.
Bone Defect Detection on Dental Osseointegration Using Structural Mode Shape
Authors: Hsieh Y.-Sh. , Chen J.-Z. , Chen Ch.-S. , Lee S.-Y. , Pan M.-Ch.
Published: September 2013

This study aims to assess clinical bone defects between an implant and jaw bone after dental implantation by examining the mode shape of structures. Different severity of bone defects was evaluated through structure resonant frequencies and their corresponding mode shapes of the implant and jaw bone by using both numerical analysis and experimentation. This study consists of two parts. First, the assumption of two kinds of boundary conditions, bonding and rubbing, was applied to simulate osseointegration in the clinical dentistry and the in-vitro bone defect model, respectively, in finite element analysis. Natural frequencies and their mode shapes of the implant/jaw were computed by the modal analysis. During the harmonic analysis, the response displacements versus frequency of implant in the buccolingual and mesiodistal directions were defined. Secondly, the structural resonant frequencies were measured by a procedure of acoustic excitation and displacement response, and then this result was compared with using the detection of an Osstell mentor.

The simulation results show that the structure local mode corresponding high-frequency resonance can be used to examine bone imperfection remarkably. Limited by extremely tiny response displacement, measuring dynamic range of the capacitive displacement sensor, the acoustic excitation-displacement response measurement can only acquire the structure global mode of the mandible corresponding to low-frequency resonance. Additionally, the Osstell mentor can assess bone defects effectively. Therefore, the above-mentioned simulations and experimental results prove that the local mode is promising to evaluate the defect severity of the dental-implantation osseointegration.
The Simplest 3- and 4-Noded Fully-Parameterized ANCF Plate Elements
Authors: Dmitrochenko Oleg , Matikainen Marko , Mikkola Aki
Published: September 2013

In this research, the simplest kinematical models of triangular and rectangular plate finite elements using the absolute nodal coordinate formulation (ANCF) are presented. The ANCF is the finite-element large-displacement-and-rotation approach, which uses the inertial-frame nodal position vectors and their derivatives (slopes) only, without employing any rotation parameters or their equivalent. As a consequence, the kinematics of the elements becomes linear, simplifying the inertia part of the equations of motion, which is also linear. In contrary, due to the need for employing the Green-Lagrange strain tensor, the elastic forces normally appear in a more complicated highly-nonlinear manner than in other large-rotation formulations. In this research, to reduce the computational burden, two new plate elements are proposed that are the simplest possible triangular and rectangular elements in the fully-parameterized ANCF: they employ transverse slopes only, without using longitudinal slopes.
Applying System Theoretical Hazard Analysis Method to Complex Automotive Cyber Physical Systems
Authors: Van Eikema Hommes Qi D.
Published: September 2013

The modern automobiles have become software intensive, with electronics features replacing many of the traditionally mechanical systems, and automating many of the drivers’ tasks. This transition brought new challenges to engineering design. The control system software exhibits unprecedented complexity, whose states cannot be exhaustively tested. Software does not fail like hardware due to random noise factors. Electronics and software update and change rapidly. Engineers have limited engineering experience and historical data to draw upon. Automating traditional manual tasks of the drivers may also lead to accidents. Safety regulation for automotive electronics is in its infancy, and standards do not yet provide adequate safety assurance.

Motivated by these challenges, this paper compares a number of hazard analysis methods for their ability to address the challenges posed by the modern automotive electronics systems. The System Theoretic Process and Analysis (STPA) framework developed for system safety engineering presents a paradigm shift, and is the most effective at identifying causes of hazards. As the first application on modern automotive electronic systems, STPA was applied to the Adaptive Cruise Control (ACC) feature. The outcome was compared with the ACC design standards and the actual vehicle implementation to illustrate the effectiveness of the method.
Exposing Students to Culturual Issues in Rice Cooker Design Through Product Archaeology
Authors: Kang Kang , Simpson Timothy W. , Okudan Kremer Gül E.
Published: September 2013

As more products compete in the global marketplace, it is increasingly important to bring cultural and societal issues into engineering education to help contextualize design decisions. When product dissection activities are used to contextualize these decisions, they focus primarily on function, form, and fabrication, failing to highlight the importance of cultural influences that can impact global product design. The paradigm of product archaeology has been developed to address the shortcomings of product dissection activities and create inductive learning activities that help students better contextualize their engineering design knowledge. Inspired by the findings in our own rice cooker dissection and analysis, an experiment is conducted to evaluate the incorporation of rice cookers into product archaeology activities in a product dissection course. The purpose of adding rice cookers to the consumer goods section of the course is to expose students to the cultural issues of rice cooker design (e.g., product functions and features based on cooking and dietary needs). Student responses were collected and analyzed, including the numbers of correct responses, sketches of mechanisms and components, suggestions for design improvements, and feedback on cultural needs. Future improvements to the exercise are also discussed.