bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison Between 2D and 3D Hand Gesture Interaction for Augmented Reality Applications
Authors: Radkowski Rafael , Stritzke Christian
Published: June 2012

This paper presents a comparison between 2D and 3D interaction techniques for Augmented Reality (AR) applications. The interaction techniques are based on hand gestures and a computer vision-based hand gesture recognition system. We have compared 2D gestures and 3D gestures for interaction in AR application. The 3D recognition system is based on a video camera, which provides an additional depth image to each 2D color image. Thus, spatial interactions become possible. Our major question during this work was: Do depth images and 3D interaction techniques improve the interaction with AR applications, respectively with virtual 3D objects? Therefore, we have tested and compared the hand gesture recognition systems. The results show two things: First, they show that the depth images facilitate a more robust hand recognition and gesture identification. Second, the results are a strong indication that 3D hand gesture interactions techniques are more intuitive than 2D hand gesture interaction techniques. In summary the results emphasis, that depth images improve the hand gesture interaction for AR applications.
Experimental Investigation of Energy Harvesting With Essential Nonlinearities
Authors: Triplett Angela , Quinn D. Dane
Published: June 2012

The advancement of technology of portable electronics and devices has increased the need for self-sufficient energy sources. This work investigates the potentiality of a vibration-based energy harvesting system based on the response of an attachment with strong nonlinear behavior. The electromagnetic coupling is achieved by a piezoelectric element across a resistive load. Typical designs utilize a linear oscillator, which limits the peak harvesting performance to a narrow band of frequencies about the natural frequency of the oscillator. An essentially nonlinear cubic oscillator is shown, with proper design, to significantly improve the range of frequencies for sufficient harvesting when compared with a tuned linear oscillator design. Numerical simulations of the proposed model reveal this wider band of frequencies harvest significant power when the system is subjected to harmonic excitation. A physical model was developed and the acquired instantaneous voltage was recorded to calculate the average power over a resistive load and to experimentally validate the numerical simulations.
Lessons Learned From a Project-Based Learning Approach for Teaching New Cognitive Product Development to Multi-Disciplinary Student Teams
Authors: Metzler Torsten , Shea Kristina
Published: June 2012

This paper presents lessons learned from a project-based approach for teaching new cognitive product development to multi-disciplinary student teams. Within the class, interdisciplinary teams with students from mechanical engineering, electrical engineering and computer science are formed. To date, the class has been run five semesters using different themes and developing more than 15 new products. Cognitive products are tangible and durable things with cognitive capabilities that consist of a physical carrier system with embodied mechanics, electronics, microprocessors and software. The surplus value is created through cognitive capabilities, e.g. perceiving, learning and reasoning, that are enabled by flexible control loops and cognitive algorithms. Common product development processes are often not applicable to this high level of interdisciplinarity and require extension and refinement. Therefore, project-focused, technical lectures, balancing technology-push and market pull, are given and specifically tailored to cognitive product design. Additionally, software and hardware prototyping workshops and toolkits are provided in combination with the support of technical and process coaches to assist the teams. Attention is especially paid to giving students hands-on experience in developing their own cognitive product starting with the generation of ideas, turning the best idea into a product concept and finally building a functional and a design prototype. Lessons learned through the refinement of the product development process and methods used as well as from student questionnaires are presented and discussed.
Synthesis of Coupler-Drivers for Four Position Planar Synthesis Tasks
Authors: Perkins David A. , Murray Andrew P.
Published: June 2012

A coupler-driver for a planar mechanism is a revolute-prismatic-revolute (RPR) chain connected between ground and one of the links of the mechanism. The focus of this work is to investigate how the use of a coupler-driver as the source of actuation alters the set of solutions for a four position task by avoiding defects relative to the joints of the actuated mechanism. Type maps are a synthesis tool used to visualize the solutions for the four position task, which previous researchers have used to identify the mechanism class and the ability to actuate each solution through the task. This work extends the type map concept to represent the number of solutions to a four position task that are drivable via either a coupler-driver or an input torque at one of the fixed joints. The use of a coupler-driver as the actuator is found to allow many mechanisms that suffer from a branch defect relative to the joints of the kinematic solution mechanism to be valid solutions. For the example four position tasks tested, the coupler-driver was found to expand the number of four-bar mechanism solutions. As part of this analysis, a variation of the derivation of the space of fixed and moving pivot pairs that produce a coupler-driver capable of actuating a single degree of freedom planar mechanism is presented.
Understanding of Emotions and Reasoning During Consumer Tradeoff Between Function and Aesthetics in Product Design
Authors: Sylcott Brian , Cagan Jonathan , Tabibnia Golnaz
Published: June 2012

In this work we investigate how consumers make preference judgments when taking into account both product form and function. In prior work, where aesthetic preference is quantified using visual conjoint methods, aesthetic preference and functional preference were handled separately. Here we introduce a new methodology for testing the hypothesis that when consumers make decisions taking into account both a product’s form and its function they employ a more complex decision making strategy than when basing their decision on form or function alone. We believe that this strategy will involve both cognitive and emotional processes. We used a two stage conjoint analysis to develop a preference function that takes both form and function into account. When compared with participant ratings of form and function combinations across 14 subjects, the model is shown to have a correlation of approximately 0.56, p < 0.001. Next we developed a novel paradigm using functional magnetic resonance imaging (fMRI) to determine what parts of the brain are primarily involved with any given tradeoff between form and function. While in the scanner, study participants were asked to make decisions between options where only form varied, where only function varied, and where form and function both varied. Results from 7 participants suggest that choices based on products that vary in both form and function involve some unique and some common brain networks as choices based on form or function alone; most important, emotion-related regions are activated during these complex decisions where form and function are in conflict. These results demonstrate the feasibility of using fMRI to address questions about the mental processes underlying consumer decisions.
Hybrid Modeling and Fractional Control of a SCKAFO Orthosis for Gait Assistance
Authors: HosseinNia S. Hassan , Romero Francisco , Vinagre Blas M. , Alonso Francisco Javier , Tejado Ines , Font-Llagunes Josep M.
Published: June 2012

SCKAFO, stance-control knee-ankle-foot orthosis, is a type of orthosis that permits free knee motion during swing while resisting knee flexion during stance, supporting thereby the limb during weight bearing. This orthosis specially assists patients who have incomplete spinal cord injury and allows them to walk with the aid of canes or crutches, maintaining a proper gait. In this paper, based on the human walking biomechanics, the SCKAFO hybrid modeling is proposed, which consists of eight different stages whose evolution is given by means of four planar sensors on each foot. In the model, it is considered that the patients can move their hip but not their knee that will be controlled using a DC motor. Two fractional order controllers are designed, following decision based control techniques, to control the knee angle. Simulation results are given in order to demonstrate the efficiency of the system performance.
Multidisciplinary Design Optimization of Modular Industrial Robots
Authors: Tarkian Mehdi , Persson Johan , O¨lvander Johan , Feng Xiaolong
Published: June 2012

This paper presents a multidisciplinary design optimization framework for modular industrial robots. An automated design framework, containing physics based high fidelity models for dynamic simulation and structural strength analyses are utilized and seamlessly integrated with a geometry model. The proposed framework utilizes well-established methods such as metamodeling and multi-level optimization in order to speed up the design optimization process. The contribution of the paper is to show that by applying a merger of well-established methods, the computational cost can be cut significantly, enabling search for truly novel concepts.
A Comparison of Different Multibody System Approaches in the Modeling of Flexible Twist Beam Axles
Authors: Sinokrot Tariq Z. , Prescott William C. , Nembrini Maurizio , Toso Alessandro
Published: June 2012

One of the challenging issues in the area of flexible multibody systems is the ability to properly account for the geometric nonlinear effects that are present in many applications. One common application where these effects play an important role is the dynamic modeling of twist beam axles in car suspensions. The purpose of this paper is to examine the accuracy of the results obtained using four common modeling methods used in such applications. The first method is based on a spline beam approach in which a long beam is represented using piecewise rigid bodies interconnected by beam force elements along a spline curve. The beam force elements use a simple linear beam theory in approximating the forces and torques along the beam central axis. The second approach uses the well known method of component mode synthesis that is based on the linear elastic theory. Using this method the deformation of the beam, which is modeled as one flexible body, is defined using its own vibration and static correction mode shapes. The equations of motion are, in this case, written in terms of the system’s generalized coordinates and modal participation factors. The linear elastic theory is used again in the third approach using a slightly different technique called the sub-structuring synthesis method. This method is based on dividing the flexible component into sub-structures, in which, the method of component mode synthesis is used to describe the deformation of each substructure. The fourth approach is based on a co-simulation technique that uses a Multibody System (MBS) solver and an external nonlinear Finite Element Analysis (FEA) solver. The flexibility of any body in the multibody system is, in this case, modeled in the external nonlinear FEA solver. The latter calculates the forces due to the nonlinear deformations of the flexible body in question and communicates that to the MBS solver at certain attachment points where the flexible body is attached to the rest of the multibody system. The displacements and velocities of these attachment points are calculated by the MBS solver and are communicated back to the nonlinear FEA solver to advance the simulation. The four approaches described are reviewed in this paper and a multibody system model of a car suspension system that includes a twist beam axle is presented. The model is examined four times, once using each approach. The numerical results obtained using the different methods are analyzed and compared.
In-Plane Nonlinear Dynamics of Wind Turbine Blades
Authors: Ramakrishnan Venkatanarayanan , Feeny Brian F.
Published: June 2012

The partial differential equation that governs the in-plane motion of a wind turbine blade subject to gravitational loading and which accommodates for aerodynamic loading is developed using the extended Hamilton principle. This partial differential equation includes nonlinear terms due to nonlinear curvature and nonlinear foreshortening, as well as parametric and direct excitation at the frequency of rotation. The equation is reduced using an assumed cantilevered beam mode to produce a single second-order ordinary differential equation (ODE) as an approximation for the case of constant rotation rate. Embedded in this ODE are terms of a nonlinear forced Mathieu equation. The forced Mathieu equation is analyzed for resonances by using the method of multiple scales. Superharmonic and subharmonic resonances occur. The effect of various parameters on the response of the system is demonstrated using the amplitude-frequency curve. A superharmonic resonance persists for the linear system as well.
Combining 3D Simulation Technology With Object-Oriented Databases: A Database Oriented Approach to Virtual Reality Systems
Authors: Hoppen Martin , Rossmann Juergen , Schluse Michael , Waspe Ralf , Rast Malte
Published: June 2012

Using object-oriented databases as the primary data source in VR applications has a variety of advantages, but requires the development of new techniques concerning data modeling, data handling and data transfer from a Virtual Reality system’s point of view. The many advantages are outlined in the first part of this paper. We first introduce versioning and collaboration techniques as our main motivation. These can also be used in the traditional file based approach, but are much more powerful when realized with a database on an object and attribute level. Using an object-oriented approach to data modeling, objects of the real world can be modeled more intuitively by defining appropriate classes with their relevant attributes. Furthermore, databases can function as central communication hubs for consistent multi user interaction. Besides, the use of databases with open interface standards allows to easily cooperate with other applications such as modeling tools and other data generators. The second part of this paper focuses on our approach to seamlessly integrate such databases in Virtual Reality systems. For this we developed an object-oriented internal graph database and linked it to object-oriented external databases for central storage and collaboration. Object classes defined by XML data schemata allow to easily integrate new data models in VR applications at run-time. A fully transparent database layer in the simulation system makes it easy to interchange the external database. We present the basic structure of our simulation graph database, as well as the mechanisms which are used to transparently map data and meta-data from the external database to the simulation database. To show the validity and flexibility of our approach selected applications realized with our simulation system so far e. g. applications based on geoinformation databases such as forest inventory systems and city models, applications in the field of distributed control and simulation of assembly lines or database-driven virtual testbeds applications for automatic map generation in planetary landing missions are introduced.
Using Product Archaeology to Embed Context in Engineering Design
Authors: McKenna Ann F. , Neumeyer Xaver , Chen Wei
Published: June 2012

Many engineering departments often struggle with meeting “the broad education necessary to understand the impact of engineering solutions in a global, economic, environmental, and societal context” (outcome h) that is required by ABET. The already packed curricula provide few opportunities to offer meaningful experiences to address this outcome, and most departments relegate this requirement to an early cornerstone or later capstone design experience as a result, making these courses an ineffective “catch all” for many ABET requirements. We address this issue by using the paradigm of product archaeology, defined as the process of reconstructing the lifecycle of a product — the customer requirements, design specifications, and manufacturing processes used to produce it — to understand the decisions that led to its development. By considering products as designed artifacts with a history rooted in their development, we embed context as a central component in developing design solutions. Specifically, in our work we have implemented several approaches to integrate contextual thinking into a senior level engineering design course. Following Kolb’s model of experiential learning and an instructional framework adapted for product archaeology (inclusive of evaluate-explain-prepare-excavate activities) we have restructured the course to embed specific and targeted reflection, dissection, and analysis activities so that students teams effectively address the global, economic, environmental, and societal factors in their design solutions. This paper provides the theoretical framework of our instructional approach, describes the specific instructional activities we implemented, and results from our pre and post survey assessments that describe the impact on students’ understanding of contextual as well engineering design topics.
Experimental Validation of a Walking Model for Planar Bipeds With Curved Feet
Authors: Martin Anne E. , Schmiedeler James P.
Published: June 2012

Bipeds with curved feet typically require less energy for walking than do point- or flat-footed bipeds, and they tend to mimic human gait more closely. Thus, understanding the effects of curved feet on bipedal walking gaits has the potential to improve both humanoid robot efficiency and human rehabilitation. This paper derives the equations of motion for planar bipeds with curved feet under the assumption, among others, of instantaneous transfer of support between the legs. The paper then verifies the mathematical model by comparing the results of simulation to previous experimental results for two very different bipedal robots — McGeer’s two-link, passive dynamic walker traversing a decline and the five-link, actuated biped ERNIE walking on a treadmill with a supporting boom. In both cases, the results from simulation match the experimental results very well despite the simplifying assumptions, indicating that the mathematical model captures the dominate dynamics of bipedal robots with curved feet.
A Procedure to Analyse and Compare the Sensitivity to Geometrical Parameter Variations of One-DOF Mechanisms
Authors: Sancisi Nicola , Zannoli Diego , Parenti-Castelli Vincenzo
Published: June 2012

Sensitivity analysis to geometrical parameter variations aims at assessing how small changes in a mechanism parameters, for instance due to tolerances and clearance, can alter its nominal motion. This issue is very important for the characterization of a mechanism and has been widely addressed in the literature, but it needs further investigations. The high number of parameters characterizing the problem and their mutual influence indeed make it difficult to assess the sensitivity from a global point of view. In this paper, a procedure is presented to characterize and evaluate the sensitivity of one-degree-of-freedom mechanisms. As an example, such a procedure is applied on two mechanisms which are the basis to design knee prosthetic devices. In this context, sensitivity analysis is important to understand how the motion generated by a prosthetic device can be influenced by small variations of its geometry or by small misalignments during the installation phase on the patient.
FEM Stress Analysis of the Characteristics of Bolted Joints Under External Loadings (In the Case Where Two Hollow Cylinders Are Clamped)
Authors: Sawa Toshiyuki , Kuwaki Kengo , Morozumi Yukio , Okumura Masahiko
Published: June 2012

In designing bolted joints, it is necessary to know the stress distributions in bolted joints. Recently, high strength bolts have been used with a higher bolt preload. As the results, the permanent set occurs sometimes at the bearing surfaces of clamped parts in a bolted joint. In addition, when an external load is applied to the bolted joint, the permanent set can be extended at the bearing surfaces. As the permanent set increases, the reduction in the bolt preload increases. Thus, it is important to estimate the reduction in the bolt preload from the reliability stand point. However, no study on the permanent set at the bearing surface under the external loading has been carried out. In this study, the stress distribution and the extension of the permanent set at the bearing surface of the bolted joint under the external tensile loading are examined using finite element Method (FEM), where two hollow cylinders are clamped with a hexagon bolt and a nut. The spring constants for the hexagon bolt and the clamped parts are analyzed using an axi-symmetrical theory of elasticity. Using the obtained results, an increment in the axial bolt force and the reduction in the bolt preload are estimated. For verification of the FEM stress analysis, the load factor of hexagon bolt was measured. The FEM results of the load factor (the increment in the axial bolt force) and the axial bolt force are in a fairly good agreement with the experimental results and the reduction of the axial bolt force. Finally, discussion is made on the appreciate bolt preload.
Capstan as a Mechanical Amplifier
Authors: Starkey Michael M. , Williams Robert L.
Published: June 2012

A capstan is simply a cylinder with a flexible body such as a string or cable wrapped around it. Capstans are generally used to assist in the lifting or pulling of heavy objects in the form of winches. By controlling the input tension on the cord, a capstan can dynamically amplify the input. It is hypothesized that a single capstan with multiple cords wrapped about it can act as numerous mechanical amplifiers. The validity of the classic capstan equation was investigated in this study. It was found that, where the classic equation is able to provide a rough estimation of the dynamics of a capstan system, a more complex equation was needed to fully define the behavior. A more complex equation was developed and compared to the experimental data. It was found to accurately describe the dynamics of the system and explanations were offered to describe the contributing forces.
Environment-Based Design (EBD)
Authors: Zeng Yong
Published: June 2012

This paper summarizes a design methodology — Environment Based Design (EBD) — developed over the last two decades. The EBD stems from the observation that design aims to change an existing environment to a desired one by generating a new artefact. Design starts from the environment, functions for the environment, and brings changes to the environment. This environment changing process implies the recursive evolution of design problems, design knowledge, and design solutions. Three basic activities are included in the EBD: environment analysis, conflict identification, and solution generation. In introducing the EBD, four major requirements for an effective design methodology are firstly formulated from the perspective of the nature of design, cognitive model of design, and the driving force underlying design. The mathematical, semantic and algorithmic foundations of the EBD are then presented to define methods and procedures for solving a design problem. Experimental validation and industrial applications are summarized to show the effectiveness of the EBD. Future research questions are also given in the paper.
Interactive Scenario-Based Teaching of Metal Casting Processes
Authors: Siddique Zahed , Saha Mrinal , Akasheh Firas , Arif Shaiful , Barua Bipul
Published: June 2012

It is well documented that students learn more effectively when they are actively involved in the learning process. Interactive scenario-based education is a novel concept expected to stimulate active learning and provide an engaging learning experience. Recently we have developed a Create your Scenario Interactively (CSI) module to teach metal casting and have implemented it in manufacturing engineering courses at the University of Oklahoma. In this paper, we discuss the impact of the CSI on students’ learning in manufacturing engineering education. The pedagogical effectiveness of the CSI instruction has been evaluated in several areas such as students’ engaging and active learning through pre-test and post-test format and survey questionnaires. Our preliminary results suggest that a majority of the students feels that the CSI module is very effective in keeping them engaged. Results also indicate that the CSI instructions help improve their understanding of the metal casting process. The details of the CSI module, implementation details, and assessment results are discussed.
Effects of a Concentrated Mass on Chaotic Vibrations of a Clamped Circular Plate With Initial Deformation
Authors: Okada Kenji , Nagai Ken-ichi , Maruyama Shinichi , Yamaguchi Takao
Published: June 2012

Experimental results are presented on effects of a concentrated mass on chaotic vibrations of a clamped circular plate. The plate has initial deformation due to initial deflection and initial in-plane compressive constraint at the boundary. The concentrated mass is attached on the center of the plate. Under periodic excitation, non-periodic responses with dynamic snap-through are generated on the plates. The responses are inspected by the Fourier spectrum, the Poincare´ projection, the maximum Lyapunov exponents and the principal component analysis. The non-periodic responses are found to be chaotic responses. The lowest mode of vibration shows the largest contribution ratio. When the concentrated mass is attached on the plate, the region of the response is shifted to the lower frequency. Furthermore, the width of the frequency region is decreased. The contribution ratio of the lowest mode slightly increases.
Platform Approaches in Manufacturing: Considering Integration With Product Platforms
Authors: Michaelis Marcel T. , Johannesson Hans
Published: June 2012

Given the latest progress in research and technology, achieving the seamless co-development of products and manufacturing systems seems rather undemanding. While a straightforward solution to this challenge is not in fact in sight, numerous ideas exist and are being pursued, both in industry and academia. One of these is to base the development of products and manufacturing systems on strategically specified and pre-defined platforms that limit the solution space in a well-defined manner while allocating desired flexibility. This paper identifies different paradigms for the joint development of products and manufacturing systems. Specifically, it looks at a platform concept originating from manufacturing rather than product design. A real-life industrial example of a robotized manufacturing station from the automotive industry illustrates a transition towards the closer integration of design and manufacturing. In this example, the existing dedicated welding station is contrasted with a modular, configurable station that can accommodate new products and different manufacturing technologies. Differences in flexibility and complexity between these two manufacturing stations are brought to light by modeling the rationale of their designs. From this process, conclusions are drawn regarding the different conditions for co-development with the two manufacturing stations. The modular concept imposes new restrictions. However, with its high degree of configurability, it can be a standard solution for the robotized manufacture of body-in-white sub-assemblies.
Geometry and Kinematics of a Plane-Symmetric Spatial Eight-Bar Linkage With Exact Straight-Line Motion
Authors: Wei Guowu , Dai Jian S.
Published: June 2012

In this paper, a novel plane-symmetric spatial eight-bar linkage with exact straight-line motion is proposed for the first time. Geometry and kinematics of the eight-bar linkage are studied and closed-form equations are presented revealing the exact straight-line motion characteristics of the linkage. It is found in this paper that, for the plane-symmetric eight-bar linkage, the angle α between the base and the straight-line traced by the trajectory of the end-effector point is only dependent on the angle φ of the isosceles triangle vertexes of the linkage but independent of the length of the links and dimension of the vertexes. The relationship between α and φ is studied and a special case that leads to parallel translation motion is revealed. Numerical example is then given to illustrate the kinematic properties of the eight-bar linkage.
An Ultrasound Transducer by Lead Zirconate Titanate (PZT) Nanofibers
Authors: Zhang Guitao , Shi Yong
Published: June 2012

In this paper, we demonstrate Lead zirconate titanate (PZT) nanofibers as a transducer to generate and detect ultrasound acoustic waves. PZT nanofibers with average diameter of 102nm were fabricated by the electrospinning method. The as-fabricated nanofibers were collected and aligned across a 10 μm silicon trench with Au electrodes. After annealing, the device was tested with the pulse/delay method. Two resonant frequencies, 8 MHz and 13MHz, were detected respectively. By using the Hamilton’s principle for coupled electromechanical systems with properly assumed mode shape, the resonant frequency was caudated. Base on the current testing result, a broadband ultrasound transducer was envisioned.
FreeLoader: An Open Source Universal Testing Machine for High-Throughput Experimentation
Authors: Amend John R. , Lipson Hod
Published: June 2012

We present a low cost, desktop size, open source, universal testing machine, designed for inexpensive high-throughput material testing. The tester can apply tensile and compressive loads up to 5 kN at rates ranging from 2 mm/min to 30 mm/min. Force measurements are achieved with ±1.8 N accuracy. The parts list for this machine represents an order of magnitude reduction in the cost per testing unit as compared to commercial systems. We describe the design and construction of the tester and validate its performance. The design, parts list, control software, and user manual are made available freely online under the open source BSD license.
From Product Dissection to Product Archaeology: Exposing Students to Global, Economic, Environmental, and Societal Impact Through Competitive and Collaborative “Digs”
Authors: Simpson Timothy W. , Okudan Gu¨l E. , Ashour Omar M. , Lewis Kemper
Published: June 2012

Product dissection activities have been very successful used in engineering courses to help anchor the knowledge and practice of engineering in students’ minds. Unfortunately, most product dissection activities tend to stress form, functionality, and fabrication, missing opportunities to explore the broader impacts of engineering design decisions. In this paper, we present initial efforts to transform product dissection activities into product archaeology exercises wherein students “dig” to uncover not only the manufacturing (i.e., economic) issues of a product, but also the global and societal context that influenced its development as well as the environmental impact of the product during its life cycle. We introduce two new classes of exercises—competitive “digs” and collaborative “digs”—to engage students in similar, yet different, ways in product archaeology. Competitive “digs” pit teams of students in a time-based competition to unearth the global, societal, economic, and environmental impact of a product while collaborative “digs” allow students to work together to dig more deeply into these issues over an extended period of time. Results from pilot offerings of both of these types of exercises are summarized and discussed along with a preliminary educational assessment of one of the collaborative “digs”. Improvements to the exercises and future work to formalize this new paradigm of product archaeology are also discussed.
Micro Injection Moulding Process and Product Characterization
Authors: Surace Rossella , Trotta Gianluca , Bongiorno Alessandro , Bellantone Vincenzo , Pagano Claudia , Fassi Irene
Published: June 2012

Due to its high efficiency for the large scale production of polymeric parts, micro injection moulding is one of the key technologies of the new millennium. Although a lot of researches have been conducted to identify the most effective processing conditions for micro injection moulding, the comprehension of the influence of all parameters on the quality, the properties and the reliability of the moulded parts is still an issue. In this context, this study aims to evaluate the effects of the micro injection moulding process conditions on the tensile properties of micro parts, investigating the influence of three main process parameters: the injection speed, the mould temperature and the melt temperature. A full factorial plan has been applied to study the contributions of these parameters and a second study has been performed to understand the synergic interaction between the two temperatures on the tensile strength. Due to its high level of potential crystallinity, a typical semi-crystalline thermoplastic resin was used in the experiments. The results of the analysis showed a great influence of the mould temperature (Tmould) on the ultimate tensile strength and of the melt temperature (Tmelt) on the deformation at the point of breaking; whereas the injection speed was significant on the overall mechanical performance. A new studied factor (Tmelt-Tmould) could affect the resulting molecular structure and consequently the mechanical behaviour, but itself is not sufficient to thoroughly explain the observed behaviour. Moreover, the visual inspection of the deformation mechanism at break shows three distinctive trends demonstrating the great variability of the mechanical properties of micro-injected specimens due to process conditions.
Screw Systems Generated by Subalgebras: A Further Analysis
Authors: Tadeo-Cha´vez A. , Rico J. M. , Cervantes-Sa´nchez J. J. , Pe´rez-Soto G. I. , Mu¨ller A.
Published: June 2012

This contribution presents further properties of screw systems generated from the sum of subalgebras of the Lie algebra, se(3), of the Euclidean group, SE(3). In particular, it is shown that they exhibit the property of having a locally constant rank. This property has been used, without proper formalization, in the design of parallel platforms. In addition, since the order of screws in a screw system — and therefore the order of their corresponding kinematic pairs within the kinematic chain that realize the screw system — is shown to be decisive for fulfilling the property of having a locally constant rank, the name screw systems may be not at all appropriate.
Effective Modal Derivatives Based Reduction Method for Geometrically Nonlinear Structures
Authors: Tiso Paolo
Published: June 2012

Effective Model Order Reduction (MOR) for geometrically nonlinear structural dynamics problems can be achieved by projecting the Finite Element (FE) equations on a basis constituted by a set of vibration modes and associated second order modal derivatives. However, the number of modal derivatives generated by such approach is quadratic with respect to the number of chosen vibration modes, thus quickly making the dimension of the reduction basis large. We show that the selection of the most important second order modes can be based on the convergence of the underlying linear modal truncation approximation. Given a certain time dependency of the load, this method allows to select the most significant modal derivatives set before computing it.
Sequential Sampling With Kernel-Based Bayesian Network Classifiers
Authors: Shahan David , Seepersad Carolyn C.
Published: June 2012

Complex design problems are typically decomposed into smaller design problems that are solved by domain-specific experts who must then coordinate their solutions into a satisfactory system-wide solution. In set-based collaborative design, collaborating engineers coordinate themselves by communicating multiple design alternatives at each step of the design process. Previous research has demonstrated that classifiers can be a communication medium for facilitating set-based collaborative design because of their ability to divide a design space into satisfactory and unsatisfactory regions. The proposed kernel-based Bayesian network (KBN) classifier uses a set of example designs of known acceptability, called the training set, to create a map of the satisfactory region of the design space. However, previous implementations used deterministic space-filling sampling sequences to choose the training set of designs. The shortcoming of deterministic space-filling sampling schemes is that they do not adapt to focus the samples on regions of interest to the design team (exploitation) or, alternatively, on regions in which little information is known (exploration). In this paper, we introduce the use of KBN classifiers as the basis for sequential sampling strategies that can be exploitive, exploratory, or any combination thereof.
Microstructure Reconstruction for Stochastic Multiscale Material Design
Authors: Liu Yu , Greene M. Steven , Chen Wei , Dikin Dmitriy A. , Liu Wing Kam
Published: June 2012

There are two critical components of connecting material and structural design in a multiscale design process: (1) relate material processing parameters to the microstructure that arises after mixing, and (2) stochastically characterize and subsequently reconstruct the microstructure to enable automation of material design that scales upward to the structural domain. This work proposes a data-driven framework to address both above components for two-phase materials and presents the algorithmic backbone to such a framework. In line with the two components above, a set of numerical algorithms is presented for characterization and reconstruction of two-phase materials from microscopic images: these include grayscale image binarization, point-correlation and cluster-correlation characterization, and simulated annealing algorithm for microstructure reconstruction. Another set of algorithms is proposed to connect the material processing parameters with the resulting microstructure by mapping nonlinear, nonphysical regression parameters in microstructure correlation functions to a physically based, simple regression model of key material characteristic parameters. This methodology, that relates material design variables to material structure, is crucial for stochastic multiscale design.
Form Function Fidelity
Authors: Tseng Ian , Cagan Jonathan , Kotovsky Kenneth
Published: June 2012

Engineering goals are typically rooted in addressing the functional needs of a product. While these engineering goals and specifications can be important in consumers’ buying decisions, many times the first impression of the product comes from judgments of the product’s aesthetic form. For this reason, this paper set out to study how well human judgment of performance based on a car’s shape correlates with the actual measured performance of the car’s shape, and what features of the car’s shape most influence this judgment. More specifically, participants were asked to rate how aerodynamic, sporty, fuel efficient, and rugged a computer generated car design appeared to them, and these ratings were analyzed against the actual aerodynamics of the vehicle as well as key indicators of sportiness and cornering stability such as center of gravity and wheel stance. The inter-rater consistency of human judgments was also studied. Using this human judgment data, the attributes in car design with the greatest effect on participant judgment of vehicle performance were identified, and were compared against their importance and effect in actual vehicle performance. Analysis of this data gives key insights about how car designers can create designs that better convey the desired goals of a car to consumers while also meeting those performance goals.
Micro Electro Discharge Milling of Freeform Micro-Features With High Aspect Ratio
Authors: Modica F. , Marrocco V. , Trotta G. , Fassi I.
Published: June 2012

Micro Electrical Discharge Machining (μEDM) technology is widely used to process conductive materials, regardless to their hardness and strength, and realize micro-sized feature components for industrial application. μEDM proves to be a very competitive fabrication technology since micro-sized features within 1 μm of accuracy and with high surface quality (<0.1 μm Ra) can be attained. When High Aspect Ratio (HAR) micro-features are machined via μEDM milling, the main problem is to identify the technological parameters and settings mainly affecting the process performance. In the present study the influence of the adjustment factor and flushing conditions are investigated and discussed for the machining of HAR cavities with different Fill Factor (FF). Material Removal Rate (MRR) and Tool Wear Ratio (TWR) are evaluated when deep cavities having variable square sections are machined on Ni-Cr-Mo steel workpiece. All tests are performed using a state of the art micro-EDM milling machine, with a Tungsten Carbide electrode tool and a dielectric oil for flushing. The experimental results presented here highlight different trends in the machining performance in dependence of AR and FF. In particular, MRR exhibits a decreasing trend where the curve slopes are strictly related to the FF and the initial adjustment factor. On the contrary, TWR, for higher FF, displays two distinct trends characterized by opposite slopes in each curve. Finally a nozzle for micro-injection with varying Aspect Ratio and Fill Factor is machined and presented as demonstrator.
Free-Form Conjugation Theory
Authors: Yu Bowen , Ting Kwun-lon
Published: June 2012

The paper presents the first theory and practice for free-form conjugation design and extends the conventional conjugate tooth profiles to free-form tooth profiles. It presents a conjugation theory that offers a rigorous correspondence between a conjugate pair and the cutter profile or contact path, discovers the necessary and sufficient conditions for non-undercutting with differential curves, and thus extends the traditional free-form single surface modeling to dual conjugate surface modeling. Free-form conjugation modeling and synthesis can be carried out through the cutter profile or the contact path surface. The paper offers a general theory and methodology for free-form modeling and synthesis of planar conjugation, extend the traditional single surface free-form modeling to dual-surface conjugation modeling, and establishes the foundation that will offer much needed design freedom enabling one searching for conjugate surfaces with optimal or desired performance in any transmission involving contact surfaces. The theory is demonstrated in gear tooth profile design through splines and thus provides a fresh perspective on gearing.
Hybrid Position-Force Control of Climbing Parallel Robot Using Electrohydraulic Servo Actuators
Authors: Banfield Ilka , Saltaren Roque J. , Puglisi Lisandro J. , Aracil Santonja Rafael
Published: June 2012

An Hybrid Position-Force control scheme for hydraulic actuators is proposed for a Climbing Parallel Robot (CPR) based on a Stewart-Gough mechanism. The hydraulics actuators are modeled, and expressed as state-space variables. The parameter identification is based on experimental data and the box-grey identification procedure, using a minimization prediction error criterion. A cascade control strategy with feedback linearization and state estimation based on two control loops is used for each hydraulic actuator. The control strategy proposed for the hydraulic actuator is implemented in a real prototype, considering a position tracking task. The model of the actuators are included in the dynamic model of the CPR obtained via the virtual work formulation, which considers the thirteen bodies that composes the Stewart-Gough robot. The proposed controller is simulated and implemented on the CPR to test the limits of its performance and the real effects of friction. The results obtained from simulation and experiments are presented and discussed.
Teaching Undergraduate Numerical Methods Through a Practical Multibody Dynamics Project
Authors: Callejo Alfonso , Garci´a de Jalo´n Javier
Published: June 2012

Among the many different approaches to teach engineering subjects, the project-based methodology turns out to be one of the most effective ones. In the field of undergraduate numerical methods, it can overcome some of its inherent difficulties. This paper considers a particular context: a general 90-hour numerical methods subject in an Industrial-Mechanical Engineering degree. The methods are applied to mechanical engineering problems such as matrix structural analysis, finite element method, multibody systems (MBS), harmonic analysis, or optimization. The article suggests how an appropriate formulation and a practical MATLAB™-based project make up a good approach for a short-time practical training on multibody dynamics (MBD) within that subject. The keys to the theoretical lessons and an example of the project are explained thoroughly. The mechanical project has to be rich in numerical methods. MBD and the finite element method fulfill this requirement. The former is chosen in this article. The students know the basics, but they have to learn everything about MBD in very little time. This experience can be useful in other educational contexts. After explaining the approach, some sample assignment exercises are described, as well as a possible way to assess the work of the students. The result of this approach is a reasonable achievement-time tradeoff shown in the solid skills acquired by the students and proven by the experience of the last few years.
Multi-Sensor Health Diagnosis Using Deep Belief Network Based State Classification
Authors: Tamilselvan Prasanna , Wang Pingfeng , Youn Byeng D.
Published: June 2012

Effective health diagnosis provides multifarious benefits such as improved safety, improved reliability and reduced costs for the operation and maintenance of complex engineered systems. This paper presents a novel multi-sensor health diagnosis method using Deep Belief Networks (DBN) based state classification. The DBN has recently become a popular approach in machine learning for its promised advantages such as fast inference and the ability to encode richer and higher order network structures. The DBN employs a hierarchical structure with multiple stacked Restricted Boltzmann Machines and works through a layer by layer successive learning process. The proposed multi-sensor health diagnosis methodology using the DBN based state classification can be structured in three consecutive stages: first, defining health states and collecting sensory data for DBN training and testing; second, developing DBN based classification models for the diagnosis of predefined health states; third, validating DBN classification models with testing sensory dataset. The performance of health diagnostics using DBN based health state classification is compared with four existing classification methods and demonstrated with two case studies.