bluuebunny/crossref_metadata_2025 huggingface dataset:
Analytical Solution of the Drive Vibration With Time Varying Parameters
Authors: Dupal Jan , Zaji´cˇek Martin
Published: June 2012

The paper deals with an approach to the analytical solution of the periodical vibration of mechanical systems with n DOF esspecially drives containing periodically varying parameters (e.g. stiffnesses). The model is described by means of the Fredholm’s matrix integral equation with degenerated kernel and a periodical Green’s function is used for the solution. The application can be shown e.g. on the Cardan’s mechanism and gear transmission having the time varying tooth stiffnesses. The result correctness is validated by means of Runge-Kutta integration method.
Nurturing Creativity and Design Teaching: Are We Doing All We Can?
Authors: Okudan Gu¨l E. , McKenna Ann , Plumb Carolyn , Ro Hyun K. , Yin Alexander
Published: June 2012

In this paper, we report on the results from a qualitative study of six exemplary engineering programs focusing on the ways and the extent of nurturing creativity in engineering students. The study (P360: Prototyping the Engineering of 2020) included data collection from students, faculty, and administrators at the six institutions. This data collection focused mainly on three student outcomes, including design and problem solving. Creativity and how creativity was nurtured, both inside the classroom and outside, often emerged as a major theme. We also support our qualitative findings with quantitative data. Overall, the results indicate that although students improve their creativity in design settings, this result is mostly a by-product of design teaching, and creativity is not taught per se. Quantitative results show that program emphasis on creativity and innovation significantly correlates to skill levels in design problem solving, interdisciplinarity, contextual awareness, and recognizing perspectives. Qualitative data provide supporting evidence for this.
Robust CRONE Design for a Variable Ratio Planetary Gearing in a Variable Speed Wind Turbine
Authors: Feytout Benjamin , Lanusse Patrick , Sabatier Jocelyn , Gracia Serge
Published: June 2012

Most wind turbines installed have traditional architectures: double-fed asynchronous machine or direct drive with full conversion, both containing several levels of control composed of PI controllers. In our application, a robust 3rd-generation-CRONE controller is used to manage a planetary gearing ratio upstream of a synchronous generator directly connected to the grid. Thus, the speed of the low shaft is controlled and unlike other architectures, no system of power electronics is required for conversion. This CRONE approach is a robust control methodology based on fractional order differentiation.
Robustness Metrics for Time-Dependent Quality Characteristics
Authors: Du Xiaoping
Published: June 2012

Quality characteristics (QC’s) are often treated static in robust design optimization while many of them are time dependent in reality. It is therefore desirable to define new robustness metrics for time-dependent QC’s. This work shows that using the robustness metrics of static QC’s for those of time-dependent QC’s may lead to erroneous design results. To this end, we propose the criteria of establishing new robustness metrics for time-dependent QC’s and then define new robustness metrics. Instead of using a point expected quality loss over the time period of interest, we use the expectation of the maximal quality loss over the time period to quantify the robustness for time-dependent QC’s. Through a four-bar function generator mechanism analysis, we demonstrate that the new robustness metrics can capture the full information of robustness of a time-dependent QC over a time interval. The new robustness metrics can then be used as objective functions for time-dependent robust design optimization.
Operational Modal Analysis in Absence of a Random Distributed Load
Authors: Culla Antonio , D’Ambrogio Walter , Fregolent Annalisa
Published: June 2012

In this paper the performance of several modal parameter estimation techniques is compared by considering a simple mechanical structure as test bed. Specifically, among Input/Output (I/O) techniques, a frequency domain poly-reference method is considered. Among Operational Modal Analysis (OMA), Frequency Domain Decomposition and poly-reference least square complex frequency-domain techniques are used. I/O technique and OMA are performed using the measurements due to a random shaker excitation. In the first case the responses and the input force are used to calculate the FRFs. On the contrary, OMA is performed by using only the set of measured responses, by supposing unknown the input force. Note that the OMA hypothesis of a random distributed force is not observed. In order to characterise the performance of the examined methods, the results obtained by the OMA are compared to the result of the I/O technique.
Digital Fractional Order Savitzky-Golay Differentiator and Its Application
Authors: Chen Dali , Xue Dingyu , Chen YangQuan
Published: June 2012

Firstly the one-dimension digital fractional order Savitzky-Golay differentiator (1-D DFOSGD), which generalizes the Savitzky-Golay filter from the integer order to the fractional order, is proposed to estimate the fractional order derivative of the noisy signal. The polynomial least square fitting technology and the Riemann-Liouville fractional order derivative definition are used to ensure robust and accuracy. Experiments demonstrate that 1-D DFOSGD can estimate the fractional order derivatives of both ideal signal and noisy signal accurately. Secondly, the two-dimension DFOSGD is obtained from 1-D DFOSGD by defining a group of direction operators, and a new image enhancing method based on 2-D DFOSGD is presented. Experiments demonstrate that 2-D DFOSGD has very good performance on image enhancement.
Quantifying Model Uncertainty Using Measurement Uncertainty Standards
Authors: Du Xiaoping , Shah Harsheel
Published: June 2012

There is always a deviation between a model prediction and the reality that the model intends to represent. The deviation is largely caused by the model uncertainty due to ignorance, assumptions, simplification, and other sources of lack of knowledge. Quantifying model uncertainty is a vital task and requires the comparison between model prediction and observation. This exercise is generally computationally intensive on the prediction side and costly on the experimentation side. In this work, a new methodology is proposed to provide an alternative implementation of model uncertainty quantification. With the new methodology, the experimental results are reported with expanded uncertainty terms around the experimental results for both model input and output. In other words, the experimental results are expressed as intervals. Then the model takes the experimental results of the input intervals and produces an interval prediction. The model uncertainty is then quantified by the difference between the model prediction and experimental observation, represented by an interval as well. By employing the standards for measurement uncertainty, the new methodology is easy to implement and could serve as a common framework for both model builders and experimenters.
Electromechanical Actuator Test Stand Coupling Design to Support Actuator Prognostic Model Development
Authors: Koopmans Michael T. , Tumer Irem Y.
Published: June 2012

Uncertainty assessment and management is becoming an increasingly essential aspect of good prognostic design for engineering complex systems. Uncertainty surrounding diagnostics, loads, and fault progression models is very real and propagating this uncertainty from component-level health estimates to the system-level remains difficult at best. In this work, a test stand is used to conduct real-time failure experiments aboard various aircraft platforms to collect failure response data, expanding the actuator knowledge base that forms the foundation of component health estimations. The research takes a step towards standardizing a test stand design to produce comparable and scalable failure data sets, fostering uncertainty reduction within the electromechanical actuator prognostic model. This paper specifically presents a method to optimize the actuator coupling for a commercially available actuator where a model was built to minimize the coupling deflection and estimate the coupling life. Using this model, researchers can rapidly develop their own electromechanical actuator test stands.
Comfort and Handling of a Commercial Vehicle With Individual Front Suspension
Authors: Yarmohamadi Hoda , Berbyuk Viktor
Published: June 2012

The main focus in the presented work is on the sensitivity analysis of the comfort and handling characteristics of a commercial vehicle with Individual Front Suspension (IFS). For the sensitivity analysis, two simulations in frequency domain are conducted: road input and steering input frequency responses. Employing the model of the tractor semitrailer combination for the above mentioned analyses, this study evaluates the influence of five damping coefficients — cab, front and rear axle shock absorbers — on our objectives. The results that are provided in Pareto fronts clearly show the great influence of the studied parameters, particularly the front axle and cab lateral dampers, on the vehicle comfort and handling for the performed simulations. Finally, the model is updated with the chassis and cab lateral damper coefficients to run a simulation on random roads for more detailed comfort examinations. This analysis confirms the obtained improvements in the outcome of the sensitivity study.
A Markov Chain Model to Maximize Revenue by Varying Refurbished Product Upgrade Levels
Authors: Behdad Sara , Thurston Deborah
Published: June 2012

Refurbishing companies receive used products with varying levels of quality. One challenge facing the remanufacturer is the extent to which upgrading should be conducted. An analytical approach is proposed to evaluate the product recovery system with stochastic variability of the quality of the components/parts returned to the remanufacturing environment. The decision process is formulated via a discrete time Markov chain model. Then, a linear program approach is applied to solve the model to determine up to which level a returned product should be upgraded. The effects of different policies (the level of upgrade) on the total expected value are studied and the optimal decision which maximizes expected average revenue is determined. An example of a copy machine is used to illustrate an application of the model. Finally, the results of the model are further investigated applying a systems dynamics approach to determine the effects of the suggested upgrade strategy on the amount of reusable inventory.
Solving the Forward Kinematic Problem of 4-DOF Parallel Mechanisms (3T1R) With Identical Limb Structures and Revolute Actuators Using the Linear Implicitization Algorithm
Authors: Tale Masouleh Mehdi , Walter Dominic R. , Husty Manfred , Gosselin Cle´ment
Published: June 2012

This paper investigates the forward kinematic problem of 4-DOF parallel mechanisms with revolute actuators and identical limb structures and performing a three translations and one rotation motion pattern. The general architecture of all the mechanisms under study in this paper originates from the type synthesis performed for 4-DOF parallel mechanisms with identical limb structures. The mathematical framework used in this paper is based on algebraic geometry where the forward kinematics and constraint expressions are explored in a seven-dimensional kinematic space by means of the so-called Study parameters (dual quaternions). In this paper, the algorithm applied for obtaining the forward kinematic and constraint expressions is based on a recent and novel approach, called linear implicitization algorithm, which is based on solving systematically a system of linear equations to determine the coefficients of the non-linear constraint equations. This paper presents also an example of a 4-DOF parallel mechanism.
Effects of Design Parameters in Cost Estimation and Cost Uncertainty Modeling
Authors: Banga Karan , Takai Shun
Published: June 2012

Case-based reasoning (CBR) is an approach which uses old cases/experiences to understand and solve new problems. In CBR, a previous case similar to the current case is used to generate a solution for the current case and usually involves adaptation of the generated solution to suit the current case. The CBR approach consists of creating a knowledge-base (or database) containing past cases (products), defining a new case, retrieving cases similar to the new case, and adjusting the solution (cost) of the retrieved cases to the new case. This paper compares CBR approach with regression analysis approach in studying the effects of varying design attribute specifications on cost estimation accuracy and cost distribution reliability. These approaches are compared and effects of defining a concept with varying design attribute specifications are studied by applying leave-one-out cross-validation to a knowledge-base of automobiles.
Multi-Stage Uncertainty Quantification for Verifying the Correctness of Complex System Designs
Authors: Hoyle Christopher , Tumer Irem Y. , Kurtoglu Tolga , Chen Wei
Published: June 2012

Designing complex systems for mission-critical applications requires a design process with focus upon maximizing the probability of meeting design requirements. Typically the design process for these systems consists of filtering and refining an initial set of conceptual designs to produce a final set of detailed designs. This final set of designs is presented to the system contracting agency or management team for design selection. In this work, a framework is presented for a multi-stage design process in which the Probability of Correctness (PoC) is utilized as a metric to sequentially filter designs from the abstract conceptual phase through the detailed design phase. This framework utilizes methods for uncertainty propagation (UP) from reliability engineering, which are organized within the framework to match the UP method with the model fidelity and data type available at each stage of the process. A case study using the Advanced Diagnostic and Prognostic Testbed (ADAPT) Electric Power System (EPS) is presented to illustrate both the verification process utilizing multiple UP methods, and also the use of the OpenModelica environment for system design. A discussion presents a generalization of the framework and the future work needed to realize the comprehensive framework for system design.
Influence of Vehicle Inertia Tensor and Center of Gravity Location on Road Accident Reconstruction
Authors: Mastinu Giampiero , Gobbi Massimiliano , Previati Giorgio
Published: June 2012

The paper is divided into two parts and deals with the accurate reconstruction of automobile accidents. In the first part of the paper, a mathematical procedure is presented to perform an accident reconstruction with the data that are usually collected by operators after the impact. Some real cases have been considered to validate the procedure. The method has allowed to identify the final location of the impacting vehicles and their initial velocity with reasonable accuracy. The second part of the paper refers to a sensitivity analysis for quantifying the effects on a proper accident reconstruction of the uncertainties of the location of the centre of gravity and of the moment of inertia around the vertical axis of the (two) crashed vehicles. The final aim of such a theoretical investigation is assessing and prescribing the measurement accuracy of the centre of gravity location and of the inertia tensor components of crashed vehicles. An existing test rig for measuring the c.g. location and the inertia tensor of crashed vehicles (pre- and post-impact), meeting the accuracy determined on the basis of the theoretical study, is presented. Contrary with respect to what it seems the current opinion, from our theoretical analysis, it appears that an accurate accident reconstruction needs accurate measurements of both the centre of gravity location and the inertia tensor of crashed automobiles.
Dynamic Modeling and Soil Mechanics for Path Planning of the Mars Exploration Rovers
Authors: Trease Brian , Arvidson Raymond , Lindemann Randel , Bennett Keith , Zhou Feng , Iagnemma Karl , Senatore Carmine , Van Dyke Lauren
Published: June 2012

To help minimize risk of high sinkage and slippage during drives and to better understand soil properties and rover terramechanics from drive data, a multidisciplinary team was formed under the Mars Exploration Rover (MER) project to develop and utilize dynamic computer-based models for rover drives over realistic terrains. The resulting tool, named ARTEMIS (Adams-based Rover Terramechanics and Mobility Interaction Simulator), consists of the dynamic model, a library of terramechanics subroutines, and the high-resolution digital elevation maps of the Mars surface. A 200-element model of the rovers was developed and validated for drop tests before launch, using MSC-Adams dynamic modeling software. Newly modeled terrain-rover interactions include the rut-formation effect of deformable soils, using the classical Bekker-Wong implementation of compaction resistances and bull-dozing effects. The paper presents the details and implementation of the model with two case studies based on actual MER telemetry data. In its final form, ARTEMIS will be used in a predictive manner to assess terrain navigability and will become part of the overall effort in path planning and navigation for both Martian and lunar rovers.
A Hierarchical Bayesian Method for Market Positioning in Environmentally Conscious Design
Authors: Zhao Yuan , Xu Jianfeng , Thurston Deborah
Published: June 2012

Environmentally conscious consumers and environmental protection legislation have been driving manufacturers to design, produce, and dispose products in a more environmentally responsible manner. One of the key issues is how to position environmentally conscious products in the marketplace. Environmentally conscious design eventually needs to make the transition into mainstream design, rather than stay in a high-profile niche application. The assumption that all consumers have the same preferences does not hold in the real marketplace. Heterogeneous customer preferences require analysis of customer choice behavior at the individual level. In addition, individual customer preferences can be clustered into aggregate preferences of different market segments that are latent within the customer base. In this paper, a Hierarchical Bayesian method is presented to integrate individual level preference information, which can be used to help manufacturers measure product attribute weights and identify appropriate market segments in which customers value the environmentally conscious design the most. An automobile design case study is used to demonstrate the proposed approach.
Integrated Piezoresistive Flexure Model in Polysilicon
Authors: Larsen Gerrit T. , Howell Larry L. , Jensen Brian D.
Published: June 2012

This paper presents a new model and test device for determining piezoresistive response in long, thin polysilicon beams with axial and bending moment inducing loads. If the piezoresistive coefficients are known, the Integrated Piezoresistive Flexure Model (IPFM) is used to find the new resistance of a beam under stress. The IPFM first discretizes the beam into small volumes represented by resistors. The stress that each of these volumes experiences is calculated, and the stress is used to change the resistance of the representative resistors according to a second-order piezoresistive equation. Once the resistance change in each resistor is calculated, they are combined in parallel and series to find the resistance change of the entire beam. If the piezoresitive coefficients are not initially known, data are first collected from a test device. Piezoresistive coefficients need to be estimated and the IPFM is run for the test device’s different stress states giving resistance predictions. Optimization is done until changing the piezoresistive coefficients provides model predictions that accurately match experimental data. These piezoresistive coefficients can then be used to design and optimize other piezoresistive devices. A sensor is optimized using this method and is found to increase voltage response by an estimated 10 times.
An Analysis of Industrial Practice for Estimating the In-Service Costs of a Product Service System
Authors: Huang Xiaoxi , Newnes Linda , Parry Glenn
Published: June 2012

An extensive range of companies have moved from providing a tangible product to offering long-term integrated product service solutions. The revenue from such offerings, in particular at the in-service stage of a product service system, has become a key area for profit generation within some companies. However, estimating the cost of providing such a service is one of the major challenges that companies encounter. The research in this paper presents a new framework for estimating the cost of in-service provision for a product service system. Within this framework the service cost factors are identified through a review of the literature and an analysis of industrial practice. Analysing seven years data of the service demanded by customers for a Chinese machine manufacturer and service provider, the key relationships are identified and described. The service provider in this study offers repair and maintenance services to ensure the machines are available for use at the customer’s sites. The results from the study found that there is not a strong correlation between the distance from the service provider to customer companies and the number of call outs for after-sales service. It was also found that there was no strong evidence to show that when there is convenient and economical transportation links between the service provider and the customer, the demand for after-sales service increases. However, there was a strong correlation between machine failure rate and the number of years in service. It was also found that preventative maintenance, which occurred after the second year of machine service, did not improve the reliability of the machine during the in-service phase. Based on the initial findings and outcomes of the study the next stage of the research is then discussed, describing how the framework will be used to estimate the cost of the in-service provision for a product service system.
Dynamic Analysis of a Micro-Resonator Driven by Electrostatic Combs
Authors: Song M. T. , Cao D. Q. , Zhu W. D.
Published: June 2012

The dynamic response of a micro-resonator driven by electrostatic combs is investigated in this work. The micro-resonator is assumed to consist of eight flexible beams and three rigid bodies. The nonlinear partial differential equations that govern the motions of the flexible beams are obtained, as well as their boundary and matching conditions. The natural matching conditions for the flexible beams are the governing equations for the rigid bodies. The undamped natural frequencies and mode shapes of the linearized model of the micro-resonator are determined, and the orthogonality relation of the undamped global mode shapes is established. The modified Newton iterative method is used to simultaneously solve for the frequency equation and identify repeated natural frequencies that can occur in the micro-resonator and their multiplicities. The Gram-Schmidt orthogonalization method is extended to orthogonalize the mode shapes of the continuous system corresponding to the repeated natural frequencies. The undamped global mode shapes are used to spatially discretize the nonlinear partial differential equations of the microresonator. The simulation results show that the geometric nonlinearities of the flexible beams can have a significant effect on the dynamic response of the micro-resonator.
More Space to Think: Eight Years of Visual Support for Rationale Capture, Creativity and Knowledge Management in Aerospace Engineering
Authors: Eng Nathan , Aurisicchio Marco , Bracewell Rob , Armstrong Gareth
Published: June 2012

Concept mapping software is emerging as a powerful tool for supporting complex thinking. The Decision Rationale editor (DRed) provides an illustrative example from industry. Eight years after its development, 700+ engineers in Rolls-Royce have received direct training, others have adopted it independently and it is increasingly used for knowledge management, creativity and communication. This study seeks lessons from these experiences to inform broader map-based tools and methods development. Semi-structured interviews were performed with 11 professionals ranging from junior engineers to chief designers. A qualitative analysis of transcripts and sample maps examined the value of new features and methods in practical contexts. Results suggest mapping is often the “path of least resistance” to organise unstructured ideas and conflicting perspectives. The flexible nature of maps, however, presents challenges for standardising methods. Feature development will require a continued balance of simplicity, learnability and functionality supported by integrated help documentation.
Decoupling of the Cartesian Stiffness Matrix: A Case Study on Accelerometer Design
Authors: Zou Ting , Angeles Jorge
Published: June 2012

The 6 × 6 Cartesian stiffness matrix obtained through finite element analysis for structures designed with material and geometric symmetries may lead to unexpected coupling that stems from discretization error. Hence, decoupling of the Cartesian stiffness matrix becomes essential for design and analysis. This paper reports a numerical method for decoupling the Cartesian stiffness matrix, based on screw theory. With the aid of this method, the translational and rotational stiffness matrices can be analyzed independently. The mechanical properties of the decoupled stiffness submatrices are investigated via their associated eigenvalue analyses. The decoupling technique is applied to the design of two accelerometer layouts, uniaxial and biaxial, with what the authors term simplicial architectures. The decoupled stiffness matrices reveal acceptable compliance along the sensitive axes and high off-axis stiffness.
A Conceptual Framework for Consistency Management in Model-Based Systems Engineering
Authors: Herzig Sebastian J. I. , Qamar Ahsan , Reichwein Axel , Paredis Christiaan J. J.
Published: June 2012

Developing complex engineering systems requires the consolidation of models from a variety of domains such as economics, mechanics and software engineering. These models are typically created using differing formalisms and by stakeholders that have varying views on the same problem statement. The challenging question is: what is needed to make sure that all of these different models remain consistent during the design process? A review of the related literature reveals that this is still an open challenge and has not yet been investigated at a fundamental level within the context of Model-Based Systems Engineering (MBSE). Therefore, this paper specifically focuses on examining the fundamentals of consistency management. We show that some inconsistencies cannot be detected and come to the conclusion that it is impossible to say whether or not a system is fully consistent. In this paper, we first introduce a mathematical foundation to define consistency in a formal manner. A decision-based approach to design is then studied and applied to the development of a real-world example. The research reveals several distinct types of inconsistencies that can occur during the design and development of a system. We show that these inconsistencies can be further classified into two groups: internal and external consistency. From these insights, the ontology of inconsistencies is constructed. Finally, requirements for possible tool support and methods to identify and manage specific types of consistency issues are proposed.
A Method for Simultaneously Satisfying Important Constraints and Dependencies for Many Different Types of Processes in Embedded Real-Time Systems
Authors: Xu Jia
Published: June 2012

In most embedded, real-time applications, processes need to satisfy various important constraints and dependencies, such as release times, offsets, precedence relations, and exclusion relations. Embedded, real-time systems with high assurance requirements often must execute many different types of processes with such constraints and dependencies. Some of the processes may be periodic and some of them may be asynchronous. Some of the processes may have hard deadlines and some of them may have soft deadlines. For some of the processes, especially the hard real-time processes, complete knowledge about their characteristics can and must be acquired before run-time. For other processes, prior knowledge of their worst case computation time and their data requirements may not be available. It is important for many embedded real-time systems to be able to simultaneously satisfy as many important constraints and dependencies as possible for as many different types of processes as possible. In this paper, we discuss what types of important constraints and dependencies can be satisfied among what types of processes. We also present a method which guarantees that, for every process, no matter whether it is periodic or asynchronous, and no matter whether it has a hard deadline or a soft deadline, as long as the characteristics of that process are known before run-time, then that process will be guaranteed to be completed before predetermined time limits, while simultaneously satisfying many important constraints and dependencies with other processes.
Robot Kinematic Design Studies for Natural Orifice Surgery
Authors: Seow Chi Min , Chin Wei Jian , Nelson Carl A.
Published: June 2012

This paper presents kinematic aspects of a multifunctional robotic manipulator for use in natural orifice surgery. A literature review of some existing surgical robots is presented. The robot folding configurations for insertion/removal are described. The kinematics and workspace of the robotic manipulator and their application in a space-constrained environment are explored as well. The main goal is to find out the best way to fully utilize limited degrees of freedom in the robot arms local to the surgical site as well as additional motions provided by the hyper-redundant, underactuated articulated drive mechanism, in order to provide the dexterity and workspace required for typical surgical interventions.
Business Object Models for Industrial Data Standards
Authors: Hunten Keith A. , Barnard Feeney Allison
Published: June 2012

Business object models, as proposed for inclusion in the ISO 10303 family of industrial data standards developed in ISO TC 184/SC4 (SC4), are a layer over the ISO 10303 architecture that is intended to simplify and make the complex standards more accessible to a wider audience, ease implementation, and improve implementation performance. This paper discusses the motivation for developing business object models in SC4, proposes a process for developing business objects, provides example business objects at different levels of complexity, and describes issues facing the two SC4 projects currently developing business object models.
On the Dynamics of Two Mutually-Coupled, Electromagnetically-Actuated Microbeam Oscillators
Authors: Sabater Andrew B. , Rhoads Jeffrey F.
Published: June 2012

This work describes the modeling, analysis, predictive design, and control of self-excited oscillators, and associated arrays, founded upon electromagnetically-actuated microbeams. The study specifically focuses on the characterization of nonlinear behaviors arising in isolated oscillators and small arrays of nearly-identical, mutually-coupled oscillators. The work provides a framework for the exploration of larger oscillator arrays with different forms of coupling and feedback, which can be exploited in practical applications ranging from signal processing to micromechanical neurocomputing.
Numerical Simulation and Virtual Reality Visualization of Horizontal and Vertical Axis Wind Turbines
Authors: Yan Nan , Okosun Tyamo , Basak Sanjit K. , Fu Dong , Moreland John , Zhou Chenn Q.
Published: June 2012

Virtual Reality (VR) is a rising technology that creates a computer-generated immersive environment to provide users a realistic experience, through which people who are not analysis experts become able to see numerical simulation results in a context that they can easily understand. VR supports a safe and productive working environment in which users can perceive worlds, which otherwise could be too complex, too dangerous, or impossible or impractical to explore directly, or even not yet in existence. In recent years, VR has been employed to an increasing number of scientific research areas across different disciplines, such as numerical simulation of Computational Fluid Dynamics (CFD) discussed in present study. Wind flow around wind turbines is a complex problem to simulate and understand. Predicting the interaction between wind and turbine blades is complicated by issues such as rotating motion, mechanical resistance from the breaking system, as well as inter-blade and inter-turbine wake effects. The present research uses CFD numerical simulation to predict the motion and wind flow around two types of turbines: 1) a small scale Vertical Axis Wind Turbine (VAWT) and 2) a small scale Horizontal Axis Wind Turbine (HAWT). Results from these simulations have been used to generate virtual reality (VR) visualizations and brought into an immersive environment to attempt to better understand the phenomena involved.
Investigation of Automated Cell Manipulation in Optical Tweezers-Assisted Microfluidic Chamber Using Simulations
Authors: Chowdhury Sagar , Svec Petr , Wang Chenlu , Seale Kevin T. , Wikswo John P. , Losert Wolfgang , Gupta Satyandra K.
Published: June 2012

Microfluidic devices are well suited for the study of biological objects because of their indirect nature of manipulation and high throughput. However, the cell manipulation process solely depends on the fluid flow and hence precise control is difficult to attain inside a microfluidic chamber. Utilizing optical tweezers as a complementary tool provides precise manipulation control. We have presented an automated cell manipulation approach using optical tweezers operating inside a microfluidic chamber. To test and demonstrate the effectiveness of the approach we have developed a physics-based simulator that is completely automated and allows high precision of manipulation.
An Investigation Into the Dynamic Response of Seat-Occupant Models Incorporating Foam Properties Identified Through Quasi-Static Compression Tests
Authors: Joshi Gauri A. , Azizi Yousof , Bajaj Anil , Davies Patricia
Published: June 2012

Vehicle occupants are sensitive to low frequency vibrations, and these can affect ride-quality and dynamic comfort. Static comfort, a function of the support provided by the seat, is also important. The transmission of vibration to seated occupants and the support provided by the seat can be controlled by appropriately designing the seats. Optimization of seat design requires accurate models of seat-occupant systems can be used to predict both static settling points and the low frequency dynamic behavior of the occupant around those points. A key element in the seat, which is a challenge to model, is the flexible polyurethane foam in the seat cushion. It is a nonlinear, viscoelastic material exhibiting multiple time-scale behavior. In this work, the static and the low-frequency dynamic response of the occupant is examined through a planar multi-body seat-occupant model, which also incorporates a model of flexible polyurethane foam developed from relatively slow cyclic compression tests. This model also incorporates profiles of the seat and the occupant, and includes relatively simple friction models at the various occupant-seat interfaces. The settling point, the natural frequencies, the deflection shapes of the occupant at particular frequencies, and the dynamic force distribution between the seat and the occupant are examined. The effects of seat foam properties on the responses as well as those of including a flexible seat-back frame are also investigated.
Study of Evolution of Global Structure Into Chaotic Itinerancy by Point Mapping Under Cell Reference Method
Authors: Jiang Jun , Guo Xu
Published: June 2012

Chaotic itinerancy is a complex phenomenon in high-dimensional dynamic systems, by which an orbit successively itinerates over low-dimensional semi-stable invariant sets in a chaotic manner. In this paper the evolution of the global structure of the coupled neural oscillators into the chaotic itinerancy is investigated by using an extended Point Mapping under Cell Reference Method. The method of Point Mapping under Cell Reference, denoted as PMUCR in short, was a numerical method developed for the global analysis of nonlinear dynamical systems with the aim to retain the accuracy of Point Mapping Method but enhance its computational efficiency. The method is extended to be able compute both stable and unstable invariant sets in highdimensional dynamical systems by taking the virtue of the cell structure and incorporate with PIM-triple method. By applying extended PMUCR method to the coupled Morris-Lecar neuron model, some important global structure changes in invariant sets during the evolution into the chaotic itinerancy are demonstrated.
Overview of Architecture Frameworks and Modeling Languages for Model-Based Systems Engineering
Authors: Reichwein Axel , Paredis Christiaan J. J.
Published: June 2012

Model-based systems engineering is a relatively new discipline. As a result, many system designers are not familiar with the main concepts of model-based systems engineering and how it can beneficially impact systems design. The paper presents an overview of architecture frameworks and modeling languages for model-based systems engineering as well as indicates future trends.
An Efficient Conflict Detecting Method for Service Design
Authors: Ota Takumi , Kimita Koji , Hosono Shigeru , Shimomura Yoshiki
Published: June 2012

In service engineering, methods for detecting and solving physical and logical conflicts (e.g., having some conflicting functions) in design solutions have been proposed that take into consideration design processes and existing cases. However, a procedure for using such methods has not yet been discussed. Given this, we believe that the efficiency of detecting conflicts in service needs to be improved. Herein, we suggest two approaches to solving this problem. The first is an efficiency-detecting method that examines functional independence, and the second relates to detecting the procedures of the conflicts in detail. In addition, a prototype system of the suggested method is implemented in Service CAD.
Fractional Optimal Control Within Caputo’s Derivative
Authors: Biswas Raj Kumar , Sen Siddhartha
Published: June 2012

A general formulation and solution of fractional optimal control problems (FOCPs) in terms of Caputo fractional derivatives (CFDs) of arbitrary order have been considered in this paper. The performance index (PI) of a FOCP is considered as a function of both the state and control. The dynamic constraint is expressed by a fractional differential equation (FDE) of arbitrary order. A general pseudo-state-space representation of the FDE is presented and based on that, FOCP has been developed. A numerical technique based on Gru¨nwald-Letnikov (G-L) approximation of the FDs is used for solving the resulting equations. Numerical example is presented to show the effectiveness of the formulation and solution scheme.
Optimal Level Set Vibration Control of Plate Structures
Authors: Ansari Masoud , Khajepour Amir , Esmailzadeh Ebrahim
Published: June 2012

This research is motivated by the need for control of flexural vibrations of lightweight plates. It addresses application of the level set method in optimal control of vibrations in plate-like structures. One of the most commonly practiced methods in control of vibration is to apply constrained layer damping patches to the surface of a structure. In order to consider the weight efficiency of the structure, the best shape and locations of the patches should be determined to achieve the optimum vibration suppression with lowest amount of damping patch. A novel topology optimization approach is proposed that is capable of finding the optimum shape and locations of the patches simultaneously. A 2D cantilever plate, undergoing flexural vibrations, will be considered. The optimal damping set will be found in the structure, such that the lowest modal energy in the fundamental vibration mode of the system is achieved. The proposed level set topology optimization method shows capability of determining the optimum damping set in structures accurately.
Back-Side Contact Gear Mesh Stiffness
Authors: Guo Yichao , Parker Robert G.
Published: June 2012

Back-side gear tooth contact happens when the anti-backlash (or scissor) gears are applied or tooth wedging occurs. An accurate description of the back-side gear tooth mesh stiffness is important to any study on gear dynamics that involves tooth wedging or anti-backlash mechanism. This work studies the time-varying back-side mesh stiffness and its correlation with backlash by analyzing the relationship between the drive-side and back-side mesh stiffnesses. Results of this work yield the general form of the back-side mesh stiffness or gear tooth variation function for an arbitrary gear pair. The resultant analytical formulae are confirmed by the simulation results from Calyx that precisely tracks gear tooth contact without any predefined relations.
Platform Strategy for Product Family Design Using Particle Swarm Optimization
Authors: Moon Seung Ki , Park KyoungJong , Simpson Timothy W.
Published: June 2012

Product family design allows innovative companies to create customized product roadmaps, to manage designers and component partners, and to develop the next generation of products based on platform strategies. In product family design, problems for determining a design strategy or the degree of commonality for a platform can be considered as a multidisciplinary optimization problem with respect to design variables, production cost, company’s revenue, and customers’ satisfaction. In this paper, we investigate strategic module-based platform design to identify an optimal platform strategy in a product family. The objective of this paper is to introduce a multi-objective particle swarm optimization (MOPSO) approach to select the best platform design strategy from a set of Pareto-optimal solutions based on commonality and design variation within the product family. We describe modifications to apply the proposed MOPSO to the multi-objective problem of product family design and allow designers to evaluate varying levels of platform strategies. To demonstrate the effectiveness of the proposed approach, we use a case study involving a family of General Aviation Aircraft. The limitations of the approach and future work are also discussed.
Identification of Constitutive Parameters for Piezo Stack Actuators Based on Online Capacitance Measurements
Authors: Islam Mohammad N. , Seethaler Rudolf J.
Published: June 2012

Piezoelectric stack actuators are commonly used in a number of different position control applications due to their compactness, high resolution, speed and dynamic properties. For accurate position control, position feedback has traditionally been employed since the parameters of the constitutive equations change with temperature and age. In addition, the identification of constitutive parameters is complicated by the presence of hysteresis voltage that is not accounted for in the linear constitutive equations. Recently, there has been a push towards sensor less control. This approach requires an accurate identification technique of the constitutive parameters. For this purpose, the constitutive equations used to identify the piezoelectric parameters are usually considered linear under a low electric field. However, at larger driving voltages hysteresis effect become significant and the parameters identified at lower excitation levels are no longer valid. This is traditionally addressed by providing constitutive parameters as a function of applied voltage. However, this is usually done for the ascending hysteresis branch only. The changes due to the descending hysteresis branch are commonly ignored. As a result, it is often difficult to match the constitutive equations to experimental data. We propose a new identification procedure that is based on online capacitance measurements of the piezo actuators. These measurements indicate, that the piezo capacitance is not constant, but a linear function of linearized piezo voltage. Using this result, we are able to construct values for the remaining constitutive parameters that are largely independent of piezo voltage. The resulting constitutive equations match our experimental actuator performance well no matter where they are applied in the hysteresis loop. This new identification technique then provides more accurate piezo models that are very useful for developing sensor less control strategies for piezo actuators.
Experimental Investigation and Theoretical Analysis of a Nonlinear Energy Sink Under Harmonic Forcing
Authors: Gourc Etienne , Michon Guilhem , Seguy Se´bastien , Berlioz Alain
Published: June 2012

In the present works, we examine experimentally and theoretically the dynamic behavior of linear oscillator strongly coupled to a nonlinear energy sink under external periodic forcing. The nonlinear oscillator has a nonlinear restoring force realized geometrically with two linear springs that extend axially and are free to rotate. Hence, the force-displacement relationship is cubic. The linear oscillator is directly excited via an electrodynamic shaker. Experiments realized on the test bench consist of measuring the displacement of the oscillators while increasing and decreasing frequencies around the fundamental resonance of the linear oscillator. Many nonlinear dynamical phenomena are observed on the experimental setup such as jumps, bifurcation, and quasiperiodic regimes. The retained nonlinear model is a two degree of freedom system. The behavior of the system is then explained analytically and numerically. The complexification averaging technique is used to derive a set of modulation equation governing the evolution of the complex amplitude at the frequency of excitation, and a stability analysis is performed.
Fractional Thermal Model of the Lungs Using Havriliak-Negami Function
Authors: Pellet Mathieu , Melchior Pierre , Abdelmoumen Youssef , Oustaloup Alain
Published: June 2012

This paper is about fractional system identification of a thermal model of the lungs. Usually, during open-heart surgery, an extracorporeal circulation (ECC) is carried out on the patient. In order to plug the artificial heart/lung machine on the blood stream, the lungs are disconnected from the circulatory system. This may results in postoperative respiratory complications. A method to protect the lungs has been developed by surgeon and anesthetist. It is called: bronchial hypothermia. The aim is to cool the organ in order to slow down its deterioration. Unfortunately the thermal properties of the lungs are not well-known yet. Mathematical models are useful and needed in order to improve the knowledge of these organs. As proved by several previous works, fractional models are especially appropriate to model thermal systems (model compacity, accuracy) and the dynamic of fractal systems. Thus, fractional models of the lungs have been determined using time domain system identification with the Havriliak-Negami function. A comparison with integer order models was also carried out. The aim of this paper is to present the results of this study.