bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and Optimization of Multiple Microchannel Heat Transfer Systems Based on Multiple Prioritized Preferences
Authors: Lin Po Ting , Zhang Jingru , Jaluria Yogesh , Gea Hae Chang
Published: September 2013

Multiple microchannel heat transfer systems have been developed for the urge of rapid and effective cooling of the electronic devices, which have become smaller and more powerful but also produced more heat. Two different types of single-phase liquid cooling, including the straight and U-shaped microchannel heat sinks, have been utilized to reduce the temperature of the electronic chips. The cooling performances however depend on the preferences of different factors such as the thermal resistances, the pressure drops, and the heat flows at the solid-fluid interfaces. Lower thermal resistance represents higher temperature reduction; lower pressure drop means lower usage of the pumping power; and higher heat flows indicates more effective cooling between the heat spreader and the liquid. In this paper, an optimization strategy based on the prioritized performances has been developed to find the optimal design variables for multiple objectives: minimal thermal resistances, minimal pressure drops and maximal heat flows. The fuzzy and correlated preferences are modeled by the Gaussian membership functions with respect to different levels of the objective function values. The overall performances are formulated based on the prioritized preferences and maximized on the Pareto-optimal solution set to find the solutions for various preference conditions. Two case studies have been discussed. The first case considered the prioritized preferences based on uni-objective function values while the second one focused on the preferences of the thermal resistances and the efficiency measures, correlatively evaluated by the flow rates, pressure drops, and heat flows.
3D Model Annotation as a Tool for Improving Design Intent Communication: A Case Study on its Impact in the Engineering Change Process
Authors: Alducin-Quintero Gerardo , Rojo Alejandro , Plata Francisco , Hernández Arturo , Contero Manuel
Published: September 2013

This paper analyzes the impact of 3D model annotations on CAD user productivity in the context of the New Product Development Process. These annotations can provide valuable information to support an improved design intent communication. Comparably, they can play the same role as source code comments to support code maintainability in software engineering. A 3D CAD model is a geometry representation and it also stores the modeling strategy used to build it. Alteration of a complex CAD model usually represents a time consuming task due to the lack of an explicit explanation of the design rationale followed to build that 3D model. An experimental study conducted with Spanish and Mexican CAD students indicates that it is possible to reduce the time needed to perform engineering changes in existing models by between 13–26% by using annotations. Also some factors that affect the impact of annotations on the engineering change process such as part and alteration complexity were identified.
Dynamics of a Rocking Horizontal Pendulum Under High Frequency Excitation
Authors: Sah Si Mohamed , McGehee Clark , Mann Brian P.
Published: September 2013

In this work, we investigate the effect of high frequency excitation on a pendulum positioned at a given distance from a tilted platform. The tilted platform is subjected to high frequency excitation. The method of direct partition of motion is applied to the governing equation to obtain the slow dynamic equation. It is shown that two stable equilibria may coexist for certain parameter values. The analytical results are in a good agreement with the numerical investigations.
An Interactive Approach to Designing Planar Parallel Manipulators Using Image Space Representation
Authors: Purwar Anurag , Anantwar Sagar , Zhao Ping
Published: September 2013

Structure equations of mechanisms are well-known to give rise to algebraic constraint manifolds that describe the space of poses available to a certain link (usually, end-effector or coupler) of open chains or mechanisms. In this paper, by using planar quaternion representation for planar displacements, we obtain constraint manifold of such manipulators and show that the task of dimensional synthesis of a planar parallel manipulator (PPM) is reduced to simple geometric manipulation of the manifold in the Image Space. Earlier, this approach has been shown to work for planar 6R closed chain mechanisms as well as for RRR- and RPR-type leg topologies of a PPM. Here, we complete the extension to other five leg topologies and provide a developer version software tool for dimensional synthesis of a PPM.
Dynamic Performance of Neck Protection Devices: Performance Analysis Based on a Simplified Multibody Model of the Human Neck
Authors: Gobbi Massimiliano , Mastinu Gianpiero , Previati Giorgio , Tarallo Ermes
Published: September 2013

This work is focused on the evaluation of the dynamic performance of different neck protection devices.

In order to evaluate the mechanical response of the safety devices, a multibody model of the human neck has been developed in Matlab™ SimMechanics™.

The mechanical behavior of the neck is described in the paper and different injury indices are presented and compared. The information about anatomy and physiology of the cervical spine of the neck has been collected from the literature, with particular focus on the mechanism of damage of vertebrae, disks and soft tissues.

The multibody model has been validated against experimental data available in the literature concerning impulsive loads representative of crash phenomena.

By means of the presented model, some relevant injury indices are computed for an accident involving a motorcyclist.

Since the focus has been set on mild injuries of the neck, the simulated crash should cause a high probability of injuries of the neck together with a low probability of damages of the head while wearing a standard helmet.

The performance of neck safety devices that link the helmet with the thoracic-shield are evaluated and compared. For sake of clearness, three types of neck safety devices are considered referencing to US patents: an airbag jacket, a 3D cushion wrapping the motorcyclist’s neck, and a “spring and dampers” system.

The airbag jacket has been modeled as a high stiffness and low deformation system by considering the airbag in its fully deployed configuration and by neglecting its dynamic performance during inflation phase. The other safety devices have been modeled as lumped parameters spring-damper systems.

A sensitivity analysis on the injury indexes has been performed by changing the stiffness and the damping parameters of these safety systems. The injury indexes collected by simulating the different neck safety systems have been compared.
Design and Analysis of a Microelectromechanical Device Capable of Testing Theoretical Models of Impact at the Microscale
Authors: Sanders John W. , Dankowicz Harry , Lacarbonara Walter
Published: September 2013

This paper proposes a conceptual design for a microscale experimental device that could be used to investigate oblique, intermittent contact while allowing for tangential slip and adhesion/stiction at the contact interface. The discussion includes a formulation of a reduced-order model of the nonlinear device dynamics. Emphasis is given to a possible contact model that incorporates normal and tangential compliance, friction-like limits on the ratio of tangential to normal contact forces, adhesive interactions, and irreversible energy loss in the normal contact interactions. A preliminary theoretical and numerical analysis is performed on this contact model in order to assess the influence of adhesion and energy loss on the contact phase. The results consider both the case of a normal collision in the absence of coupling between normal and tangential degrees of freedom as well as the general case of an oblique impact with such coupling. The paper argues that there is great value in an experimental validation of such a model for microscale contact, as a growing number of devices either rely on contact directly or must accommodate and design for its possible occurrence. In addition, mention is made of a number of inconsistencies and paradoxes observed in macroscopic models of rigid-body contact with friction that warrant validation or resolution through appropriate experimental designs.
Measurement of Damping in Bolted Joints
Authors: Goyder Hugh , Ind Philip , Brown Daniel
Published: September 2013

A structure may be built-up from subsystems that are attached to each other by bolted joints. If the structure is allowed to vibrate the bolted joints provide a significant contribution to the absorption of energy and are thus an important source of vibration damping. The details of such damping should be included in computer simulations but unfortunately too little is known about joints to make this possible. An experimental apparatus has been developed to investigate damping and is described in this paper together with two sets of experiments. The experimental apparatus consists of two masses and a spring which can be set into vibration and exercise the bolted joints. The decay of the vibration enables the rate of energy dissipation to be measured. The accuracy of the measurement process is examined in detail and a relationship between the noise in the measurements and the errors in the determination of damping formulated.
Reducing the Complexity When Modelling Damping in Vibrating Systems
Authors: Goyder Hugh
Published: September 2013

If a frequency spectra or frequency response function is known for a structure what physical model can be generated to represent it? This is an important question for computer based simulations where a translation must be made between a spectra and a computer model. This is particularly difficult if damping is to be modelled. Investigation of electrical theory shows that this problem has been examined in detail due to the need to construct circuits that have specific spectra. However, before ideas can be borrowed from electrical theory it is necessary to develop vibration theory so that it aligns perfectly with electrical theory. To achieve this a method for representing mass is suggested which is a generalisation of the usual method and involves using a system of levers so that force is equal to mass times the derivative of relative velocity rather than absolute velocity. It is then shown that following electrical theory a damped spectra may be represented by an undamped sequence of masses and springs terminated by just one dashpot. Such a model is of considerable theoretical interest as well as having utility in computer simulations.
A Quadricycle for Urban Mobility
Authors: Galmarini G. , Gobbi M. , Mastinu G.
Published: September 2013

The need to decrease pollution in urban zones has pushed toward severe regulations in term of low-emission limits. The effect of this “environmental awareness” is an increased interest in electric vehicles (EV).

The construction of a EV is presented in the paper. This vehicle has been designed specifically to be powered by electric motors, the suspension system and the general layout have been developed accordingly.

According to the European technical regulations, the vehicle has been designed for a city use. The main features of GreenFun, (this is the name of the prototype), are an extensive use of composite and lightweight materials, a special suspension system layout, a 4WD powertrain realized by means of 4 electric motor hubs and the use, for the first time in a production vehicle, of 4 measuring wheels that are able to measure the forces acting between the pneumatic tires and the road. These information are used as input for the vehicle control systems in order to enhance performance and safety.

In the paper, the most relevant vehicle subsystems are described in detail (chassis, wheel, suspensions, powertrain, energy management, control system, …).
Design, Construction and Employment of a Sustainable “Urban Concept” Race Vehicle
Authors: Galmarini G. , Gobbi M. , Mastinu G.
Published: September 2013

The construction of a plug-in electrical race vehicle is presented in the paper.

The vehicle is a prototype developed to be used for the Shell Eco-Marathon (SEM) competition. The main aim of SEM is to minimize fuel consumption. According to the technical regulations and the overall dimensions, the layout of the vehicle has been estimated in order to reduce the mass and the aerodynamic resistance of the vehicle. A high performance aerodynamic shape has been developed starting from the “Morelli’s shape” which has been further optimized to reduce the aerodynamic drag. A CFD analysis has been completed to refine the vehicle shape and to reach the final body geometry. To reduce the frontal area the wheels have been connected to the main body by using CFRP wing beams and both suspension system and powertrain, have been integrated into the wheels. A highly efficient powertrain has been developed and an electronic differential has been implemented. All the subsystems have been optimized both to reduce the motion resistance of the vehicle and to maximize the efficiency.

A numerical model of the vehicle has been developed in order to aid the design and to simulate the race strategy on different competition tracks. The model has been validated by considering data acquired during the race.
Using Industrial Robots for Hardware-in-the-Loop Simulation of Spacecraft Rendezvous and Docking
Authors: Ma Ou , Flores-Abad Angel , Boge Toralf
Published: September 2013

One of the most challenging and risky operations for spacecraft is to perform proximity Rendezvous and Docking (R&D) autonomously in space. To ensure a safe and reliable operation, such a mission must be carefully designed and thoroughly verified before a real space mission can be launched. This paper describes the control strategy for achieving high fidelity contact dynamics simulation of a new, robotics-based, hardware-in-the-loop (HIL) R&D simulation facility which uses two industrial robots to simulate the 6-DOF dynamic maneuvering of the two docking satellites. The facility is capable of physically simulating the final approaching within a 25-meter range and the entire docking or capturing process in a satellite on-orbit servicing mission. The paper discusses the difficulties of using industrial robots for HIL contact dynamics simulation and the proposed robot control strategy for dealing with these difficulties.
Accurate Range Estimation Using Terrain Preview for Power Wheelchairs
Authors: Zhang Xiaoli , Zhang Wei
Published: September 2013

Battery-powered wheelchairs require accurate and reliable range prediction to offer the maximum visibility of the current battery state to users, and to help them schedule future trip plans as well as fulfill the maximum battery economy potential. It is also one of the most critical parameters of wheelchairs to ensure the safety of users. However, range prediction is a very complicated issue by the fact that batteries are subject to current profiles, external influences, history of battery use, and aging. The prediction is even more challenging with unknown future driving conditions. The aim of this paper is to use a preview of a 3-D map, geographic information systems, and global positioning systems to develop an accurate range estimation system for battery-powered wheelchairs. This allows range prediction based on previewed driving road conditions. The nonlinearity of Li-ion batteries is also taken into consideration by using a circuit based battery model. Altogether, this methodology offers robustness and accuracy under varying operating conditions. Simulation results are presented to validate the proposed estimation method.
On the Numerical Classification of the Singularities of Robot Manipulators
Authors: Bohigas Oriol , Zlatanov Dimiter , Manubens Montserrat , Ros Lluís
Published: September 2013

This paper is concerned with the task to obtain a complete description of the singularity set of any given non-redundant manipulator, including the identification and the precise computation of each constituent singularity class. Configurations belonging to the same class are equivalent in terms of the various types of kinematic and static degeneracy that characterize mechanism singularity. The proposed approach is an extension of recent work on computing singularities using a numerical method based on linear relaxations. Classification is sought by means of a hierarchy of singularity tests, each formulated as a system of quadratic or linear equations, which yields sets of classes to which an identified singularity cannot belong. A planar manipulator exemplifies the process of classification, and illustrates how, while most singularities get completely classified, for some lower-dimensional subsets one can only identify a restricted list of possible singularity classes.
Value-Focused Thinking: Combining Product Development and Entrepreneurial Product-to-Market Strategies
Authors: Neutschel Bernd , Gaus Olaf , Raith Matthias G. , Vajna Sándor
Published: September 2013

This paper examines how the generation of entrepreneurs 50+ should be addressed in order to raise their interest for improving their skills, and how young entrepreneurs and students can profit from the seniorpreneurs’ expertise in production processes and market knowledge as well as from their networks. To promote the promising synergies arising from the collaboration of young and elderly entrepreneurs a project was initiated that combines an integrated product development with business plan design support. Prospective entrepreneurs with industrial experience (seniorpreneurs) and innovative product ideas are matched with multidisciplinary student teams to generate a going-to-market prototype as a basis for starting new businesses. From the standpoint of research and development the balance is excellent with several promising product innovations and business plans for entrepreneurial implementation. The perspective of science and technology transfer demands an urgent desideratum to bring the accumulated value potential into the market.
Automatically Populating the Biomimicry Taxonomy for Scalable Systematic Biologically-Inspired Design
Authors: Vandevenne Dennis , Verhaegen Paul-Armand , Dewulf Simon , Duflou Joost R.
Published: September 2013

Although Biologically-Inspired Design (BID) is gaining popularity, state-of-the-art approaches for systematic BID are still limited by the required interactive work which is proportional to the applied biological database size. This interactive work, depending on the adopted methodology, might encompass model instantiation for each strategy in the biological database, classification into a predefined scheme or extensive result filtering. This contribution presents a first scalable approach to systematic BID with the potential to leverage large numbers of biological strategies. First, a focused webcrawler, based on a combination of Support Vector Machines (SVM), continuously searches for biological strategies on the Internet. The solution to this needle-in-a-haystack task is shown to produce biological strategies interesting for cross-domain Design-by-Analogy (DbA). These resources are then automatically positioned into Ask Nature’s well-known Biomimicry Taxonomy; a 3-level hierarchical classification scheme that enables designers to identify biological strategies relevant to their specific design problem. This paper details the architecture of the proposed system, and presents results indicating the feasibility of the applied approach.
Kinematic and Dynamic Analysis of Flexible-Link Parallel Robots by Means of an ERLS Approach
Authors: Vidoni Renato , Boscariol Paolo , Gasparetto Alessandro , Giovagnoni Marco
Published: September 2013

The use of parallel kinematic structures allows to design light manipulators with higher dynamic performance with respect to serial robots. In this work, the issue of accurately modelling the dynamics of lightweight flexible-link parallel robots has been investigated. The Equivalent Rigid-Link System (ERLS) formulation, useful for describing the dynamic evolution of 3D serial robots with flexible-links, has been extended to Parallel-Kinematic-Machines (PKM) both from the theoretical and from the software implementation points of view. Standard robotics concepts of 3D kinematics are exploited to formulate and solve the ERLS kinematics, thus allowing to easily work with this formulation. A simulator, capable of predicting the deformations due to the elasticity of the links, has been developed and some industrial case-studies have been implemented to validate it. The formulation and the developed simulator will give the opportunity to extensively study the deformations of parallel manipulators, allow to predict the vibrations of the system, and, then, compensate them.
Comprehensive Product Platform Planning (CP3) Using Mixed-Discrete Particle Swarm Optimization and a New Commonality Index
Authors: Chowdhury Souma , Messac Achille , Khire Ritesh
Published: September 2013

A product family with a common platform paradigm can increase the flexibility and responsiveness of the product-manufacturing process and help take away market share from competitors that develop one product at a time. The recently developed Comprehensive Product Platform Planning (CP3) method allows (i) the formation of sub-families of products, and (ii) the simultaneous identification and quantification of platform/scaling design variables. The CP3 model is founded on a generalized commonality matrix representation of the product-platform-plan. In this paper, a new commonality index is developed and introduced in CP3 to simultaneously account for the degree of inter-product commonalities and for the overlap between groups of products sharing different platform variables. To maximize both the performance of the product family and the new commonality measure, we develop and apply an advanced mixed-discrete Particle Swarm Optimization (MDPSO) algorithm. In the MDPSO algorithm, the discrete variables are updated using a deterministic nearest-feasible-vertex criterion after each iteration of the conventional PSO. Such an approach is expected to avoid the undesirable discrepancy in the rate of evolution of discrete and continuous variables. To prevent a premature stagnation of solutions (likely in conventional PSO), while solving the high dimensional MINLP problem presented by CP3, we introduce a new adaptive diversity-preservation technique. This technique first characterizes the population diversity and then applies a stochastic update of the discrete variables based on the estimated diversity measure. The potential of the new CP3 optimization methodology is illustrated through its application to design a family of universal electric motors. The optimized platform plans provide helpful insights into the importance of accounting for the overlap between different product platforms, when quantifying the effective commonality in the product family.
Mapping for Design Decision Support in Industry
Authors: Eng Nathan , Aurisicchio Marco , Bracewell Rob , Armstrong Gareth
Published: September 2013

There has been a significant loss of spatial thinking support in the move from paper to computer-based work. Map-based software methods reported here fill this gap while resolving general challenges in deploying software tools into active industrial practice.

The Decision Rationale editor (DRed) has been in use over nine years and 700 engineers have been trained within the partner company. Semi-structured interviews were performed with 13 engineers from diverse departments and with a range of experience levels. Collected examples were analysed for successful methods (what), common contexts of use (where) and advantages over existing tools (why).

Map use seems to focus on problems where multiple poorly defined options need sorting in order to progress work. The diversity of use cases demonstrates a need for increased investment in flexible visual tools to aid human thinking. Future work will expand on the set of collected examples, including attempts to generalize lessons to other software. More detailed experiments are also needed to better understand specific cognitive benefits in the work environment.
Hydraulic Instability Onset Detection in Kaplan Turbines by Monitoring Shaft Vibrations
Authors: Pennacchi P. , Borghesani P. , Chatterton S. , Vania A.
Published: September 2013

Design of hydraulic turbines has often to deal with hydraulic instability. It is well-known that Francis and Kaplan types present hydraulic instability in their design power range. Even if modern CFD tools may help to define these dangerous operating conditions and optimize runner design, hydraulic instabilities may fortuitously arise during the turbine life and should be timely detected in order to assure a long-lasting operating life.

In a previous paper, the authors have considered the phenomenon of helical vortex rope, which happens at low flow rates when a swirling flow, in the draft tube conical inlet, occupies a large portion of the inlet. In this condition, a strong helical vortex rope appears. The vortex rope causes mechanical effects on the runner, on the whole turbine and on the draft tube, which may eventually produce severe damages on the turbine unit and whose most evident symptoms are vibrations. The authors have already shown that vibration analysis is suitable for detecting vortex rope onset, thanks to an experimental test campaign performed during the commissioning of a 23 MW Kaplan hydraulic turbine unit.

In this paper, the authors propose a sophisticated data driven approach to detect vortex rope onset at different power load, based on the analysis of the vibration signals in the order domain and introducing the so-called “residual order spectrogram”, i.e. an order-rotation representation of the vibration signal. Some experimental test runs are presented and the possibility to detect instability onset, especially in real-time, is discussed.
Exploration of Mobility Modes Arising From the Breakdown of a Basic Regular Tetrahedron
Authors: Chen Yin M. , Cappelleri David
Published: September 2013

One of the most important considerations in the design of robots is mobility. How does the system traverse the terrain and environment where it is expected to operate? In past efforts, engineers and scientists have received inspiration from man-in-the-loop vehicles and modes of mobility used by animals. While amazing advancements have been achieved, this top-down approach tends to focus on one specific solution to a problem which may cause other solutions to be overlooked. This paper approaches the mobility problem from a different point of view. Starting with the most basic three dimensional shape, a regular tetrahedron, we explore seven different modes of mobility arising from simple modifications of the initial shape. These resultant modes are then resolved into corresponding, existing mechanisms that are already widely applied. By using this bottom-up approach, we are able to explore available mobility modes in a much more comprehensive manner. Instead of starting with a complex system in mind, engineers will be able to use simple building blocks to enable different desired mobility behaviors.
Interactive UAS Path Planning Using Particle Swarm Optimization and Flight Mechanics
Authors: Holub Joseph , Foo Jung Leng , Winer Eliot
Published: September 2013

Military engagements are continuing the movement toward automated and unmanned vehicles for a variety of military tasks. One important piece of automating is the ability to perform path planning quickly, safely, and reliably for unmanned aerial systems (UASs). Path planners often ignore the UAS’s ability to perform the maneuvers necessary to fly through the specified waypoints, instead relying on them to fly as close as possible. To date, path planning algorithms have been limited to providing only a single solution without input from an operator. This project attempts to incorporate operator experience in the path planning process. Particle Swarm Optimization (PSO) allows the generation of multiple optimized three-dimensional flight paths for the operator to choose from. This paper improves upon a previously developed method by incorporating flight mechanics equations into the optimization problem formulation. The new problem formulation ensures that the returned flight paths do not violate maximum load factor (G-force), minimum velocity (stall velocity), or the minimum turning radius.
Dynamic Characteristics of Fluid Force Induced by Swirling Leakage Flow Between Rotational and Stationary Disks
Authors: Sugiyama Takayuki , Kaneko Shigehiko
Published: September 2013

Axial self-excited vibration may be induced in a balance piston by fluid with a tangential velocity component that flows into the piston orifices. To avoid such vibration, knowledge of the dynamic characteristics of axial self-excited vibration induced by swirling leakage flow is required at the design stage.

In this research, the effect of axial rotation and swirl strength on the added fluid force coefficients is clarified by modeling the piston orifice as the combination of rotational and stationary disks, and deriving the unsteady fluid force generated by swirling leakage flow between the disks.

As a result, reduction of the relative velocity in the circumferential direction is shown to destabilize the oscillatory system. In particular, the effect of swirl strength on the fluid force coefficient is found to be larger in the case of the divergent channel than in the case of the parallel flow path.
Determination of State Space Matrices for Active Vibration Control Using ANSYS Finite Element Package
Authors: Daraji A. H. , Hale J. M.
Published: September 2013

This paper concerns optimal placement of discrete piezoelectric sensors and actuators for active vibration control, using a genetic algorithm based on minimization of linear quadratic index as an objective function. A new method is developed to get state space matrices for simple and complex structures with bonded sensors and actuators, using the ANSYS finite element package taking into account piezoelectric mass, stiffness and electromechanical coupling effects.

The state space matrices for smart structures are highly important in active vibration control for the optimisation of sensor and actuator locations and investigation of open and closed loop system control response, both using simulation and experimentally.

As an example, a flexible flat plate with bonded sensor/actuator pairs is represented in ANSYS using three dimensional SOLID45 elements for the passive structure and SOLID5 for the piezoelectric elements, from which the necessary state space matrices are obtained.

To test the results, the plate is mounted as a cantilever and two sensor/actuator pairs are located at the optimal locations. These are used to attenuate the first six modes of vibration using active vibration reduction based on a classical and optimal linear quadratic control scheme. The plate is subject to forced vibration at the first, second and third natural frequencies and represented in ANSYS using a proportional derivative controller and compared with a Matlab model based on ANSYS state space matrices using linear quadratic control. It is shown that the ANSYS state space matrices describe the system efficiently and correctly.
Representation: Extracting Mate Complexity From Assembly Models to Automatically Predict Assembly Times
Authors: Owensby Eric , Namouz Essam Z. , Shanthakumar Aravind , Summers Joshua D.
Published: September 2013

The work in this paper uses neural networks to develop a relationship model between assembly times and complexity metrics applied to defined mate connections within SolidWorks assembly models. This model is then used to develop a Design for Assembly (DFA) automation tool that can predict a product’s assembly time using defined mate connections within SolidWorks assembly models. The development of this new method consists of: creating a SolidWorks (SW) Add-in to automatically extract the mate connections from SW assembly models, parsing the mate connections into graphs, implementing a new complexity training algorithm to predict assembly times based on mate graphs, and evaluating the effectiveness of the new method. The motivation, development, and evaluation of the new automated DFA method are presented in this paper. Ultimately, the method that is trained on both fully defined and partially defined assembly models is shown to provide assembly time prediction results that are typically within 25% of target time, but with one outlier at 95% error, suggesting that a more robust training set is needed.
Passive, Transitioning Mounts for Simultaneous Shock and Vibration Isolation
Authors: Shahid Emad , Ferri Al
Published: September 2013

A design strategy to simultaneously mitigate the effects of both shock and vibration is introduced. The proposed isolation mount is a passive, transitioning mount and consists of sliding friction elements in series connection with springs and dampers. A linear and a displacement dependent viscous damper are considered, while linear, hardening and softening springs, are considered. The isolation mount’s response is determined by numerical simulation. For a single-degree-of-freedom system, the tradeoff curve for a half-sine velocity input is determined, as is the nonlinear transmissibility for harmonic excitation. The method is found to achieve satisfactory isolation against shock events as well as persistent harmonic inputs. The suggested mount configuration was also found to have good performance against a ‘combined’ input with both resonant and transient content.
Design of an Orthosis for the Weight Balance of Human Lower Limbs
Authors: Shieh Win-Bin , Chen Dar-Zen , Wu Chia-Chun
Published: September 2013

Most existing lower limb orthosis use actuators and active controller to guide the motion of human lower limbs. Actuators with relatively large power are usually required to compensate the gravity effect of the human lower limbs, even for a normal walking. Hence, design of an orthosis for the weight balance of human lower limbs is desired. For the motion compatibility, the human hip joint is treated as a planar pair and the knee joint as a revolute pair. As a consequence, while the lower limb is in motion, the exact positions of the mass centers of the human lower limbs cannot be obtained. Hence, in this work, topological synthesis of the orthosis mechanisms, which can trace the mass centers of the human thigh and shank, respectively, is implemented. The weight balance of the human lower limbs is achieved by fitting a minimum number of zero-free-length springs. Based on the anthropometric parameters, dimensions of the lower limb orthosis is determined and the proposed design is justified by the simulation executed by the software of ProEngineer. Finally, a first generation prototype is built.
A Framework of Design for Affordances Using Affordance Feature Repositories
Authors: Kim Yong Se , Shin Jin Woo , Kim Sun Ran , Noh Ji Hye , Kim Na Ree
Published: September 2013

People interact with artifacts, either products or services, in their lives. These interactions are based on two-way communication between people and artifacts. The characteristics of artifacts that induce natural activities of people, affordances, play critical roles in making interactions successful and meaningful. The notion of affordance features, structural elements of artifacts that provide affordances, has been proposed earlier. In this paper, a methodological framework for design for affordances is proposed where repository of affordance features are used. First affordances are identified through function-task interaction matrices or use activity observations. Using affordance feature repository where many alternative structural elements for a specific affordance are stored together with corresponding design constraints and contexts, affordance features for those identified affordances are retrieved considering similarities between the target design constrains and context and those of the affordance features in the repository. Using the clues given by such affordance features, the new affordance feature is to be designed through an analogical reasoning. We present this design for affordance framework as well as an illustrative case where various designers designed affordance features of a tumbler coffee cup using an affordance feature repository.
Beyond Hands-on-Learning: Fostering Creativity in Student Competitive Teams
Authors: Siddique Zahed
Published: September 2013

Engineering educators and practitioners have suggested that collaborative-competitive team design events promote innovation. These competitions are popular, and they attract sponsors and participants. Beyond being popular, they are believed to provide rich learning opportunities for students. We are currently investigating combining student centered learning to have a more appropriate mix of theory and experience (hands-on activities) to provide a complete experiential learning environment to foster innovation and creativity.

In this paper we investigate the theoretical models that can be used to model the Sooner Racing Team (SRT) of University of Oklahoma. Experiential Learning is the foundation to develop the competencies of students engaged in SRT. The SRT is setup as a learning organization and relies on peer-learning to facilitate developing innovation related meta-competencies.
Controlled Buckling of Piezoelectric Beams for Direct Energy Harvesting From Passing Vehicles
Authors: Karami M. Amin , Inman Daniel J.
Published: September 2013

A piezoelectric device is introduced and modeled to directly interact with the tires of passing vehicles and generate electrical power for roadside applications. Piezoelectric beams are vertically placed on the surface of the road to generate energy from the load of passing vehices. A metal cap is connected to the top end of the bimorphs. The vertical motion of the metal cap is limited by the containing fixture of the device. Tires of the passing vehicles pass over the metal cap and force the bimorph into buckling. The buckling of the piezoelectric beam generates significant amount of power. By controlling the extent of deformation of the beam we make sure that the beam is not damaged by the buckling. To this end, the amount of axial recession of the metal cap (equal to axial deformation of the beam) is precision controlled by the containing fixture. When the beam deflects it axially shrinks due to geometric nonlinearities. This lowers the metal cap. After a certain amount of deformation the metal cap rests on the containing fixture and the tire load is no more transmitted to the piezoelectric beam.

In this paper the performance of the proposed energy harvesting device is analytically modeled. Geometric nonlinearities and piezoelectric couplings have been included in the model. The vibrations of the device are transient. Power is generated when the tire pushes down the metal cap and when the metal cap springs back after the tire has passed. The design criteria for the device are discussed. It is demonstrated that the device can be realized with commonly used piezoelectric patches and can generate hundreds of milliwatts from the moving traffic. The device is not prone to resonance and generates notable amounts of power from passing of each tire. It therefore can be used as a self-sufficient sensor for traffic control.
A Mathematical Programming-Based Approach for Architecture Selection
Authors: Kerzhner Aleksandr A. , Paredis Christiaan J. J.
Published: September 2013

Modern systems are difficult to design because there are a significant number of potential alternatives to consider. The specification of an alternative includes an architecture (which describes the components and connections of the system) and component sizings (the sizing parameter for each component). In current practice, designers rely mainly on their experience and intuition to select a desired architecture without much computational support and then spend most of their effort on optimizing component sizings. In this paper, an approach for representing an architecture selection as a mixed-integer linear programming optimization is presented; existing solvers are then used to identify promising candidate architectures at early stages of the design process. Mathematical programming is a common optimization technique, but it is rarely used for architecture selection because of the difficulty of manually formulating an architecture selection as a mathematical program. In this paper, the formulation is presented in a modular fashion so that model transformations can be applied to transform a problem formulation that is convenient for designers into the mathematical programming optimization. A modular superstructure representation is used to model the design space; in a superstructure a union of all potential architectures is represented as a set of discrete and continuous variables. Algebraic constraints are added to describe both acceptable variable combinations and system behavior to allow the solver to eliminate clearly poor alternatives and identify promising alternatives. The framework is demonstrated on the selection of an actuation subsystem for a hydraulic excavator, although the solution approach would be similar for most mechanical systems.
Type Synthesis of Two Degrees-of-Freedom Rotational Parallel Mechanisms With a Fixed Center-of-Rotation Based on a Graphic Approach
Authors: Wu K. , Yu J. J. , Li S. Z. , Zong G. H. , Kong Xianwen
Published: September 2013

Mechanisms usually have to be particularly designed to meet the high-performance requirements in terms of different applications. For instance, Two degrees of freedom (DOF) rotational parallel mechanisms (RPMs) with a fixed center-of-rotation can eliminate parasitic motion and could provide the rotary stage with excellent dynamic stability, good controllability and easy operation. Therefore, this paper mainly aims at synthesizing 2-DOF RPMs with fixed center-of-rotation, a class of special RPMs with potential excellent performances. A graphic approach based on freedom and constraint spaces is introduced firstly. The constraint spaces of a class of the existing 2-DOF RPMs are illustrated, and the corresponding type synthesis patterns are summarized by comparing the geometric properties of those spaces with the mechanism characteristic. After fully decomposing the four-dimensional constraint space into sub-constraint spaces, a general type synthesis procedure is proposed based on the freedom and constraint topology. Two novel 2-DOF RPMs with fixed center-of-rotation are constructed based on the proposed method and procedure. The proposed graphic approach proves to be effective and simple to synthesizing those parallel mechanisms with some special performance.
Trajectory Estimation of Human Mass Center Based on an Inertia Identification Approach
Authors: Xiu Wenwu , Lu Qi , Ma Ou
Published: September 2013

Mass center of a human body is not a fixed point on the human body because the inertia distribution of the human body changes with body posture. Real-time estimation of the location of human mass center is often required for many biomechanical or biomedical applications. This is not an easy task if the inertia properties of the human’s body segments are unknown. This paper presents a technique for estimating the trajectory of the human mass center based on a recently developed inertia properties identification technology which was derived based on the impulse-momentum principle. The proposed technique assumes a human body as a general treelike multibody system, such that the mass center of the human is predictable with the knowledge of the barycentric parameters of the human. The latter can be identified using inertia identification method. This technique is advantageous because it requires only the 3D motion capture data as its primary input and does not need to know the inertia and geometric parameters of individual body segments of the human. The paper presents a dynamic simulation based study of the proposed estimation technique and also describes an ongoing experimental testing.
Effects of Process Parameters on the Properties of Replicated Polymeric Parts
Authors: Trotta Gianluca , Bellantone Vincenzo , Surace Rossella , Fassi Irene
Published: September 2013

The increasing demand for small and even micro scale parts is boosting the development of reliable micro system technologies. Micro-fabrication process capabilities should expand to encompass a wider range of materials and geometric forms, by defining processes and related process chains that can satisfy the specific functional and technical requirements of new emerging multi-material products, and ensure the compatibility of materials and processing technologies throughout these manufacturing chains. Micro injection moulding is the process of transferring the micron or even submicron precision of microstructured metallic moulds to a polymeric products. It represents one of the key technologies for micro manufacturing because its mass production capability and relatively low production cost. Polymers have relatively low cost, and offer good mechanical and thermal strength, electrical insulation, optical transparency, chemical stability and biocompatibility.

In this work the authors investigate the micro injection moulding process parameters on the overall quality of a miniaturized dog-bone shaped specimen. The aim of the experimentation is to calibrate the process and set the machine for the correct filling of the component. A set of injection parameters are selected for study by experimental plan and simulation tool and then discussed. Simulation results are used to better understand the polymer flow behaviour during the filling phase. A commercial software is used and input data, collected during the micro injection moulding process, are included using as performance indicators flow front position and moulded mass. Process simulation can provide, at the present time, mostly qualitative input to the designer and process engineer. Two different polymers materials are tested and evaluated in relation to the process replication capability: Polyoxymethylene (POM) and Liquid Cristal Polymer (LCP). Finally, the moulding factors with significant statistical effects are identified. The holding pressure and holding time for POM and the holding pressure and injection velocity for LCP show the highest influence on achieving high part mass.
Foldability and Constraint Analysis of Two 3US Parallel Mechanisms
Authors: Qin Yun , Dai Jian S.
Published: September 2013

Due to advantages of large-span, compact storage and high portability, foldable mechanisms have a promising prospect in aeronautics and astronautics applications. Two configurations of 3US parallel mechanisms with full foldability are constructed and their mobility and motion characteristics are further analyzed. This paper starts from geometrical arrangements of Hooke joints. Aimed at achieving full foldability, Hooke joints axes are placed along opportune directions, and lead to two configurations of 3US parallel mechanisms with anticlockwise folding and clockwise deploying motions. The analytic expression of the deployable ratio is presented and a numerical example is evaluated. This paper then applies constraint analysis in two configurations. In particular, constraint-screw systems of three limbs and those of platforms are investigated, followed by twist systems of platforms being derived as reciprocals of their wrench systems. The similarity and difference of motions allowed by two configurations are further addressed by comparison of their platform twist systems.