bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of Optimal Cable Configurations in the Design of a 3-DOF Cable-Driven Robot Leg
Authors: Bryson Joshua T. , Agrawal Sunil K.
Published: January 2015

The operational workspace of a cable-driven serial robot is largely dictated by the choice of cable placement and routing. As robot complexity increases with additional cables and degrees of freedom, the problem of designing a cable architecture can quickly become challenging.

This paper builds upon a previously described methodology to identify and analyze optimal cable configurations, expanding the approach to a 3-DoF robot leg driven by four cables. The methodology is used to analyze configuration trends in the routing and placement of the cables which achieve the desired range of motion for the robot. The results of the analysis are used to inform the design of a cable architecture which is shown to be capable of controlling the robot through the desired task.
A Dual-Process Analysis of Design Idea Generation
Authors: Moore Dylan , Sauder Jonathan , Jin Yan
Published: January 2015

A traditional engineering education primarily teaches students to use analytical methods when solving problems, which are effective in most real-world situations. However, heavily analytical approaches often hinder creative output and therefore more intuitive methods have the potential to increase novelty in design. Dual-process theory is an established model in psychology and human decision making that separates fast, intuitive Type 1 processes from slow, analytical Type 2 processes, but to this point has not been applied to engineering design methodology. A exploratory dual-process pilot study of a design experiment using retrospective protocol analysis exposed the difference in novelty of ideas produced by intuitive and analytical thinking. The preliminary results suggest that Type 1 intuitive thinking is correlated with a higher average idea novelty up to a threshold. An equal balance of Type 1 and Type 2 thinking maximized novelty potential. Understanding this relationship and the importance of intuitive thinking in the design process is important to improving the effectiveness of conceptual design thinking and has implications in design education and modeling cognitive design processes.
Understanding Damping in Linear Multi-Degree of Freedom Systems
Authors: Goyder Hugh
Published: January 2015

A system with damping is much more difficult to model than an undamped system. In particular, the effect of damping on a multi-degree-of-freedom system is not a straightforward extension of the damped found in single-degree-of-freedom systems. The complications of a multi-degree-of-freedom system are first examined by investigating the acoustic modes of a pipe with energy leaking from one boundary. This system can be modelled exactly. It is found that individual modes of vibration cannot be separated and are always coupled by damping effects which may involve some modes being active and not passive. Furthermore if damping sinks are increased the damping ratios can either increase or decrease. The damping of systems with fewer degrees-of-freedom are then examined to determine how damping coupling behaves. It is found that a two-degree-of-freedom system exhibits increasing and decreasing damping values as the magnitude of a damping sink is varied.
Measurement of Damping in a Chain of Bolted Joints
Authors: Goyder Hugh , Ind Philip , Brown Daniel
Published: January 2015

A chain of bolted joints forming a series system has been investigated theoretically and experimentally with the objective of understanding how damping is generated by a combination of bolted elements. The overall aim is to be able to predict damping so that computer based simulations can include damping effects. The theoretical simulation shows that adding more bolted joints with damping to a chain of joints will generally decrease the damping. An experimental investigation of a chain of joints showed that there are significant non-linear effects that must be taken into account when attempting to measure the damping of joints. A novel signal processing procedure was developed for this purpose and the damping of a chain of joints measured for one to ten joints. It is observed that the damping is very small (damping ratios of about 0.00004 are typical). Furthermore in the conditions investigated (where there is no slip in the joints) the damping is similar to the damping of the material from which the system is constructed.
Nonlinear Forced Vibration Analysis of Fluid Conveying Nanotubes Under Electromagnetic Actuation
Authors: Saadatnia Zia , Esmailzadeh Ebrahim , Younesian Davood
Published: January 2015

Nonlinear forced vibration of fluid-conveying nanotubes based on Euler-Bernoulli beam theory under electromagnetic actuation is studied. The nanotube is modeled as cantilever type beam and the effects of fluid motion and external harmonic excitation are considered in the governing equation of the structure vibration. The Galerkin procedure is applied in order to discretize the governing equation of vibration of the system. The well-known multiple scales method is utilized to investigate the primary resonance in the forced vibration of nanotubes. The effects of various parameters, namely, fluid velocity, position of applied force, aspect ratio and electromagnetic excitation on the primary resonance of the system are fully investigated. It is revealed that the electromagnetic excitation is highly influential on the frequency response of the considered system.
Concept for an Integrated Workflow Planning of Dental Products Based on Federative Data Management
Authors: Heister Reinhard , Anderl Reiner
Published: January 2015

Workflows to produce dental products by using CAD/CAM technology are very complex. Each patient needs an individual restoration. The challenge is to provide a patient individual production aiming at a price of mass production. But every single job has to run through an individual development as well manufacturing process. Typically, three stakeholders are involved in the workflow. The dentist performs the treatment and defines requirements for restoration. The dental laboratory plans the workflow and designs the reconstruction by using a dental CAD system. Subsequently, a milling center produces the restoration. Because of these highly heterogeneous workflows, diverse data streams and incompatibilities result. Often improper partners and resources are involved in the workflow. This fact is a significant source for errors. An additional complication is that errors are often discovered in late phases of the workflow.

To avoid high costs and unacceptable delivery times, the aim is to develop a new concept for integrated workflow planning. The concept depends on three parts: Federative dental data management (FDDM) as a basic approach, including anticipated logic and structured activities. The federative data management provides a loosely coupling of heterogeneous systems crossing enterprise borders by using web technology. The FDDM service depends on APP technology. Each participant applies its specialized APP: FDDMz (dentist), FDDMd (dental laboratory) and FDDMf (milling center). FDDM services enable a continuously integrated workflow throughout the whole process of a patient individual production. Each participating enterprise is able to register its available processes and resources. Information about resources like 3D dental scanner or milling machines are able to add, according to a global data model schema. This schema depends on an integrated information model with eight partial models: Collaboration, resource, process, workflow, requirements, product, work preparation and production model. This integrated information model provides dental information including interlinked objects. Through a proper anticipation logic, conclusions about later phases can be anticipated already at early phases. The last conceptual part is workflow management on frame of structured activities. By combining the information network with the anticipation logic, filtering of appropriate partners, processes, resources and sequences is supported. Next, a prototypical implementation is demonstrated exemplarily. This concept delivers an important contribution to increase process reliability and quality as well as to reduce delivery times and costs for digital dental workflows.
Cognitive-Based Search Strategies for Complex Bio-Nanotechnology Design Derived Through Symbiotic Human and Agent-Based Approaches
Authors: Egan Paul F. , Cagan Jonathan , Schunn Christian , LeDuc Philip R.
Published: January 2015

Complex systems are challenging for engineers to understand and design. This work demonstrates a synergistic cognitive and agent-based methodology for developing and implementing rule-based strategies that improve human search performance in optimization design tasks. The domain of our study is the design of synthetic myosin-based systems, the biologically-based building block of muscle. We began with an initial cognitive study of users solving design tasks with three varied difficulties using a graphical user interface, and tracked how they manipulated design variables in their search process. User search behaviors resulting in the best and worst designs were then examined. Trends were identified that were used to formulate three strategies automated by computational agents solving the same tasks as the users. The most successful identified strategy implemented by the agents was a combination of univariate searches to learn parameter relationships and then applying that knowledge in greedy local searches. On one of the three tasks, an initial random search improved results. A subsequent cognitive study was conducted with users implementing the best agent-tested strategies. Users implementing the strategy performed significantly better than users performed in the first study with no provided strategy. These results show the power of synergistic human and agent-based approaches, in that cognitive-based findings can provide a starting place for computational search algorithms to begin testing strategies. Experimentation through agent-based methods via fast and extensive automated searches can then produce effective strategies that are given back to users. Our primary findings demonstrate that these agent-tested strategies significantly improve human search performance in designing these complex systems.
Vibrations of an Axial Bar Experiencing Periodic Unilateral Contact Using the Wavelet Balance Method
Authors: Jones Simon , Legrand Mathias
Published: January 2015

Efficiently predicting the vibratory responses of flexible structures which experience unilateral contact is becoming of high engineering importance. An example of such a system is a rotor blade within a turbine engine; small operating clearances and varying loading conditions often result in contact between the blade and the casing.

The method of weighted residuals is a effective approach to simulating such behaviour as it can efficiently enforce time-periodic solutions of lightly damped, flexible structures experiencing unilateral contact. The Harmonic Balance Method (HBM) based on Fourier expansion of the sought solution is a common formulation, though it is hypothesized wavelet bases that can sparsely define nonsmooth solutions may be superior. This is investigated herein using an axially vibrating rod with unilateral contact conditions. A distributional formulation in time is introduced allowing periodic, square-integrable trial functions to approximate the second-order equations. The mixed wavelet Petrov-Galerkin solutions are found to yield consistent or better results than HBM, with similar convergence rates and seemingly more accurate contact force prediction.
Multi-Level Design Optimization of Reverse Osmosis Water Desalination Powered via Photovoltaic Panels With Battery Storage
Authors: Kim Jihun , Hamza Karim , El-Morsi Mohamed , Nassef Ashraf O. , Metwalli Sayed , Saitou Kazuhiro
Published: January 2015

Reverse osmosis (RO) is one of the main commercial technologies for desalination of water with salinity content too high for human consumption in order to produce fresh water. RO may hold promise for remote areas with scarce fresh water resources, however, RO energy requirements being in the form of electric power have few options in such areas. Fortunately, scarce rainfall is often associated with abundant sunshine, which makes solar photovoltaic (PV) power an attractive option. Equipping a photovoltaic powered reverse osmosis (PV-RO) desalination plant with battery storage has an advantage of steadier and longer hours of operation, thereby making better use of the investments in RO system components, but the additional cost from including batteries may end up increasing the overall cost of fresh water. It is therefore of paramount importance to consider the overall cost-effectiveness of the PV-RO system when designing the desalination plant. Recent work by the authors has generalized the steady operation model of RO systems to hourly adjusted power-dispatch via a proportional-derivative (PD) controller that depends on the state of charge (SOC) of the battery, yet the operating conditions; namely pressure and flow for a given power dispatch were only empirically selected. This paper considers a multi-level optimization model for PV-RO systems with battery storage by considering a “sub-loop” optimization of the feed pressure and flow given power dispatch for a fixed RO system configuration, as well as a “top-level” optimization where the system configuration itself is adjusted by the design variables. Effect of the sub-loop optimization is assessed by comparing the obtained cost of fresh water with the previous empirically adjusted system for locations and weather conditions near the city of Hurgada on the Red Sea.
A Unified Kinetostatic Analysis Framework for Planar Compliant and Rigid Body Mechanisms
Authors: Turkkan Omer Anil , Su Hai-Jun
Published: January 2015

Although many dynamic solvers are available for planar mechanisms, there is no readily accessible static solver that can be used in analysis of planar mechanisms with elastic components which achieve motion utilizing deformation of elastic members. New simulation tools are necessary to better understand the compliant mechanisms and to increase their usage in daily life. This framework was developed to fill this gap in planar mechanism design and analysis. The framework was written in MATLAB and is capable of kinematic and static analysis of planar mechanisms with compliant joints or links. Detailed information on implementation of the code is presented and is followed by the capabilities of the framework. Finally, the simulation results were compared with the Adams software to test the validity of the framework.
Tire-Ground Normal Force Estimation From Vehicle System Identification and Parameter Estimation
Authors: Kolansky Jeremy , Sandu Corina , Els Schalk
Published: January 2015

Ground vehicle stability controllers can be significantly improved through knowledge of the vehicle’s tire-ground normal force. This work demonstrates a proof-of-concept study of such an estimator. The method involves work from two previous methods that perform real-time estimation of the vehicle’s mass and horizontal CG position. Inclusion of the previous work provides the foundation for a comprehensive method that estimates the tire-ground normal load of a ground vehicle that is invariant with respect to the vehicle parameters.
A Formal Model of Human Interactions for Service Ecosystem Design
Authors: Ko Hyunwoong , Lee Sangwon , Shin Dongmin , Moon Seung Ki
Published: January 2015

In this digital era, the natures of services are becoming increasingly complex and diverse due to the convergences between the existing human-centered services and other supportive device services, or interactions between heterogeneous services. Expecting this trend is to be accelerated more, new scientific and engineered approaches to the service design are needed more than ever. In this context, a service designed conceptually and abstractly has significant limitations that keep the customers’ satisfaction from advancing above a certain level. Hence, in an initial service design phase, a service delivery process can be expressed quantitatively through a systematic analysis of its natures and the goals. In this paper, a human-centered complex service system is newly defined as service ecosystem. This study proposes a method for designing service processes as a Discrete Event System (DES) in formal ways by utilizing the concepts of affordance, preference, and a Affordance-based Finite State Automata (FSA) modeling methodology. The proposed design method suggests a model framework that focuses on service actions that reflects related properties of customers, employees, and environment entities and their interactions quantitatively. The formally expressed relations between properties of service entities such as customer, employee, and service environment provide guidelines for service designers in a more scientific way than traditional ones. In addition, it is expected that it will enable to add computational to the human-centered service system design and control and develop effective reusable controllers for complex service deliveries as well.
Experimental and Numerical Analysis of the Effect of Segmentation on Modal Loss Factor of Constrained Layer Damped Beam
Authors: Hujare Pravin P. , Sahasrabudhe Anil D. , Chinchawade Sanket D.
Published: January 2015

This paper presents experimental investigation on the damping effects of constrained layer treatment by cutting the constraining layer and constrained layer of viscoelastic material (VEM). The constraining layer causes shear in the damping material as the structure deforms. The shear deformation occurring in the viscoelastic core is mainly responsible for the dissipation of energy.

The shear deformation in the VEM is not significant in regions where the bending moment is maximal. Mostly only extensional deformation occurs in the damping layer. The local high-shear deformation in the damping material is produced by placing a cut at the region of highest curvature. Cutting both the constraining and the constrained layer, which leads to segmentation, increases the shear deformation at that position. This appropriate position of high bending moment for segmentation is obtained by MATLAB program.

The modal loss factor of constrained layer damped (CLD) beam is obtained by half-power bandwidth method using FFT analyzer. The CLD beams are prepared as per ASTM Standard E 756-05. Extensive experiments are conducted by making number of separate segmented CLD beams of different viscoelastic damping materials.

A three dimensional model of cantilever CLD beam has been used for numerical analysis. In this work, finite element commercial software MSC/NASTRAN is used to simulate the dynamic response of a CLD beam. The modal loss factor of constrained layer damped (CLD) beam is measured by Modal Strain Energy (MSE) Method.

This is a new method for enhancement of damping capabilities of constrained layer damping. It is found that the performance of segmented CLD beam using passive treatment shows significant improvement in modal loss factor which leads to vibration attenuation of beam. The numerical results are corroborated with experimental data obtained for segmented CLD beam. The analyzed finite element models are found to provide reliable results and compared very well with experimentally acquired data.
Type Synthesis of 2-DOF 3-4R Parallel Mechanisms With Both Spatial Parallelogram Translational Mode and Equal-Diameter Spherical Rotation Mode
Authors: Kong Xianwen , Yu Jingjun
Published: January 2015

Parallel manipulators (PMs) with multiple operation modes are novel reconfigurable PMs which use less number of actuators and can be reconfigured without disassembly. This paper deals with the type synthesis of 2-DOF PMs with both spatial parallelogram translational mode and equal-diameter spherical rotation mode. At first, a 2-DOF 3-4R overconstrained PM is proposed based on a 5-DOF US equivalent PM proposed in the literature. From this 2-DOF PM, we further obtain a 3-4R PM for equal-diameter spherical rotation and a 3-4R PM for spatial parallelogram translation. By finding the common conditions for the 2-DOF 3-4R PM for spatial parallelogram translation and 2-DOF 3-4R PM for equal-diameter spherical rotation, the types of 2-DOF 3-4R PMs with both spatial parallelogram translational mode and equal-diameter spherical rotation mode are then obtained. This work enriches the types of PMs with multiple operation modes and overconstrained mechanisms.
Kinematic Optimization of the Arm of a Working Machine
Authors: Alba Antonio , Bucchi Francesco , Frendo Francesco , Gabiccini Marco
Published: January 2015

The aim of this work is to develop an optimization methodology for the design of the arm of a small-sized working machine. The workspace and a reference maneuver are firstly defined together with a pre-defined redundant kinematic topology. The kinematic synthesis is framed as a constrained multi-objective problem with respect to link length variables. The constraints consider the capability of the machine to follow the assigned trajectory and to fulfill the joint limits. The cost function incorporates the solution of the inverse kinematics and uses several indices, e.g., total link lengths, manipulability, energy consumption. The multi-objective optimization problem is solved employing the weighting method, converting the initial problem into a single-objective one. The final scalar cost function is minimized by the Nelder-Mead method. On the basis of the outcomes of numerical simulations, the effectiveness and versatility of the developed procedure for the design of novel working machine arms is verified.
Methodic of Rational Cutting Conditions Determination for 3-D Shaped Detail Milling Based on the Process Numerical Simulation
Authors: Kiselev Igor , Voronov Sergey
Published: January 2015

The paper is devoted for the analysis of the dynamics effect on the 5-axis milling process of flexible details. The integrated model of milling dynamics composed by block principle in the paper is presented. The model consist of: 1) dynamical model of tool; 2) dynamical model of machined detail based on Finite Element Method (FEM); 3) phenomenological model of cutting forces and 4) algorithm of geometry modeling for instant machined chip thickness calculation. Regeneration mechanism of cutting and calculation of the machined surface are into this algorithm embedded. The elaborated model is adapted for 5-axis processing of the profiled details with 3-D complex geometry. Alteration of workpiece dynamic characteristics while the allowance removal is considered by the special algorithm of FEM grid changing based on the results of cutting geometry modeling. The results of modeling give us opportunity determine cutting forces, estimate the machined surface quality, calculate the magnitude and the character of tool and detail vibrations under the specified cutting conditions. The conception of increasing the process quality and the machinability for 3-D shaped details machining is offered in the paper. Applying the specified efficient conditions the undesired dynamical effects can be excluded on the base of the results of multi-variant simulation for milling dynamics varying the technological parameters at the different region of the processing route.
The Role of the Orthogonal Helicoid in the Generation of the Tooth Flanks of Involute-Gear Pairs With Skew Axes
Authors: Figliolini Giorgio , Stachel Hellmuth , Angeles Jorge
Published: January 2015

Camus’ concept of Auxiliary Surface (AS) is extended to the case of involute gears with skew axes. In the case at hand, we show that the AS is an orthogonal helicoid whose axis a) lies in the cylindroid and b) is normal to the instant screw axis of one gear with respect to its meshing counterpart; in general, the helicoid axis is skew with respect to the latter. According to the spatial version of Camus’ Theorem, any line attached to the AS, in particular any generator g of AS itself, can be chosen to generate a pair of conjugate flanks with line contact.

While the pair of conjugate flanks is geometrically feasible, as they always share a line of contact and the tangent plane at each point of this line, there are poses where the flanks even have a common Disteli axis. Then there is a G2-contact at the striction point and the two surfaces penetrate each other.

The outcome is that the surfaces are not realizable as tooth flanks. Nevertheless, this is a fundamental step towards the synthesis of the flanks of involute gears with skew axes.
High Performance Parallelized Centroid Estimation of Image Components for Full Field Measurements
Authors: Iliopoulos Athanasios , Michopoulos John G.
Published: January 2015

Full field measurement methods require digital image processing algorithms to accomplish centroid identification of components of the image of a deforming structure and track them through subsequent video frames in order to establish displacement and strain measurements. Unfortunately, these image processing algorithms are the most computationally expensive tasks performed in such methods. In this work we present a set of new algorithms that can be used to identify centroids of image features that are shown to be orders of magnitude faster than conventional algorithms. These algorithms are based on employing efficient data structures and algorithmic flows tailored to optimally fit in shared memory parallel architectures.
The Y-Prize Competition: An Inverted X-Prize Competition for Commercializing University Research
Authors: Hayward Rebecca , Eckert Michelle , Thomas Justin , Whitzer Mickey , Chaudhuri Saikat , Fitzsimons Tom , Hsu David , Yim Mark , Kumar Vijay
Published: January 2015

We have seen an increase in engineering competitions for high school and collegiate students ranging from concrete canoes [1] to human powered vehicles [2], FIRST Robotics [3] to iGem [4], and hackathons to business plan competitions. Each of these efforts challenges students to develop new ideas, methodologies, technologies, and designs to solve problems. Indeed, on a larger scale, X-Prize competitions foster innovation by getting top inventors to compete against one another to create solution methodologies in specific problem domains (e.g., automotive, space, or genomics).

We have developed the Y-Prize competition that flips the X-Prize structure by challenging students to innovate in the problem space instead of the solution space. In the problem space, students compete to develop the best applications for technological solutions that have been developed in university research laboratories. The three goals of the Y-Prize competition are: a) Expose a wide range of students in and outside engineering to emerging technology and to shine the spotlight on the opportunities in research labs on campus; b) Educate university students on the challenges inherent with technology transfer in research laboratories and engage them in technological innovation; and c) Develop and evaluate a new methodology for innovation based on cutting-edge university research which dramatically increases the number of students engaged in technology transfer.
A Preliminary Study of New Interaction Devices to Enhance Virtual Socket Design
Authors: Colombo Giorgio , Rizzi Caterina , Facoetti Giancarlo , Vitali Andrea
Published: January 2015

This paper presents a research work on the augmented interaction applied to an innovative platform to design lower limb prosthesis, in particular the prosthetic socket. The underlining idea is to experiment low-cost hand-tracking devices, to manipulate the 3D virtual model of the socket using hands as traditional done by the prosthetist. The goal is to make available a modeling tool, named Socket Modeling Assistant-SMA that permits to replicate/emulate manual operations usually performed by the prosthetist during the traditional development process. Two devices have been considered and compared: the Leap Motion device and the Intel Gestures Camera. To this end a set of gestures has been identified to make more natural the interaction with SMA. Preliminary tests and results reached so are described and discussed.
Semi-Analytic Iterative Solution for the Adhesive Contact Between a Micro-Indenter and a Graded Elasticity Coating
Authors: Chidlow Stewart J. , Chong William W. F. , Teodorescu Mircea
Published: January 2015

This paper proposes a hybrid (semi-analytic) solution for determining the contact footprint and subsurface stress field in a two-dimensional adhesive problem involving a multi-layered elastic solid loaded normally by a rigid indenter. The subsurface stress field is determined using a semi-analytic solution and the footprint using a fast converging iterative algorithm. The solid to be indented consists of a graded elasticity coating with exponential increase of decay of its shear modulus bonded on a homogeneously elastic substrate. By applying the Fourier Transform to the governing boundary value problem, we formulate expressions for the stresses and displacements induced by the application of line forces acting both normally and tangentially at the origin. The superposition principle is then used to generalize these expressions to the case of distributed normal pressure acting on the solid surface. A pair of coupled integral equations are further derived for the parabolic stamp problem which are easily solved using collocation methods.
“Pain Index Survey” for Flipped Classroom in Design Education
Authors: Liu Ang , Lu Stephen C.-Y. , Dai Yun
Published: January 2015

The purpose of the flipped classroom approach is to enhance the effectiveness of interactions in class. Nevertheless, in practice, simply asking students to watch lecture recordings at home will not automatically lead to more structured interactions in class. To address this challenge, this paper introduces a new method called the pain index survey, which functions to collect, aggregate, and analyze student’s early feedback in terms of how painful they feel over each content slide during their before-class learning. The accumulated pain index survey result can facilitate the teaching/learning of design in two ways. First, different students’ common feedbacks will enable the instructor to identify those universally perceived learning difficulties and to address them accordingly via guided instructor-student interactions in class. Second, different students’ complementary feedbacks will facilitate the instructor to form study groups respectively to promote the peer-to-peer interactions after class. Two case studies are presented to share some of our preliminary lessons and observations.
A Novel Pressure Compensating Valve for Low-Cost Drip Irrigation
Authors: Wiens A. Josh , Winter Amos G.
Published: January 2015

This paper presents a novel pressure-compensating flow restrictor for low-cost/low-pressure drip irrigation systems. There are nearly one billion subsistence farmers in the developing world who lack the resources and opportunities to rise out of poverty. Irrigation is an effective development strategy for this population, enabling farmers to increase crop yields and grow more lucrative plant varieties. Unfortunately, as a large fraction of subsistence farmers live off the electrical grid, the capital cost of solar or diesel powered irrigation systems makes them unobtainable. This cost could be drastically reduced by altering drip irrigation systems to operate at a decreased pressure such that lower pumping power is required. The work presented here aims to accomplish this by designing a drip emitter that operates at 0.1 bar, 1/10 the pressure of current products, while also providing pressure-compensation to uniformly distribute flow over a field.

Our proposed pressure compensating solution is inspired by the resonating nozzle of a deflating balloon. First, a reduced order model is developed to understand the physical principles which drive the cyclic collapse of the balloon nozzle. We then apply this understanding to propose a pressure compensating emitter consisting of compliant tube in series with a rigid diffuser. A scaling analysis is performed to determine the ideal geometry of the system and the reduced order model is applied to demonstrate that the proposed design is capable of pressure compensation in the required operation range. Preliminary experiments demonstrating the collapse effect are presented, along with initial work to translate the concept to a robust physical device.
Time-Varying Frequency Formula for the Purely Nonlinear Damped Oscillator
Authors: AL-Shudeifat Mohammad A.
Published: January 2015

The frequency of the purely nonlinear and non-conservative oscillator is a time-varying quantity due to the presence of damping. For the nonlinear oscillator addressed here, only cubic-power stiffness nonlinearity is considered. The nonlinear frequency of the conservative nonlinear oscillator is dependent on the initial energy induced into the system. However, for the non-conservative and purely nonlinear oscillator, the instantaneous frequency is dependent on the instantaneous energy of the system. Consequently, the exact amplitude decay formula obtained in a recent publication for such oscillator is accurately applied here to obtain an accurate analytical formula for the time-varying frequency of the considered system. Excellent agreement between the results obtained by the new time-varying frequency formula presented here and both numerical simulation and wavelet transform has been clearly observed. This analytical formula is found to be accurate in identifying the instantaneous frequency change of the system regardless of its physical parameters and the initial input energies.
Identifying Trends in Analogy Usage for Innovation: A Cross-Sectional Product Study
Authors: Ngo Peter , Turner Cameron J. , Linsey Julie
Published: January 2015

Design-by-analogy, including bio-inspired design, is a powerful tool for innovation and engineers need better tools to enhance ideation. To support tool creation, an exploratory cross-sectional empirical product study of 70 analogy-inspired products is conducted to report trends and associations among factors in the analogy-inspired design process, giving a general account of real-world practices. Products are randomly sampled from three technology magazines and a bioinspired design database. Seven variables are developed and used to classify each example according to design team composition, analogy mapping approach, analogies used, and design outcomes. Results suggest few differences between problem-driven approaches, which start from a design problem and find solutions in analogous domains, and solution-driven approaches, which begin with knowledge in an analog domain and find design problems to solve. For instance, results suggest that both approaches yield products at about the same frequency, and both yield products with improved performance at statistically-indistinguishable rates — thus, neither approach can be presently concluded to be advantageous over the other for improving product performance. Overall, few associations are detected between design outcome variables and other variables, thus precluding recommendations for how to compose design teams, what approaches to promote, and what number and source of analogies to support in order to achieve the outcomes measured in this study.
On the Validation of a Multiphysics Theory for a Static Contact With Rough Surfaces
Authors: Michopoulos John G. , Young Marcus , Iliopoulos Athanasios , Jones Harry N.
Published: January 2015

In an effort to address the validation of a recently developed multifield and multiscale rough contact theory we are applying it for a particular experiment. The experiment involves the contact between two hollow cylinders with an annular disk in between them. The contact surface is rough and the entire stack is exposed to compressive mechanical load and a high electric current pulse. Solving the necessary multi-physics partial differential equations leads to establishing the spatiotemporal distribution of relevant fields and the identification of the contact resistance as a function of mechanical pressure and current. In addition to providing typical results for all selected fields present during the experiment and the simulation, we also provide a comparison between the experimentally acquired resistance histories with the numerically derived ones to address validation aspects of the general multiphysics contact theory.
Manufacturing Evolution Through Servitization: Empirical Evidence on Relationship Between Manufacturing Capability and Economic Advantages
Authors: Zebardast Mahnoosh , Okudan Kremer Gül E. , Taisch Marco
Published: January 2015

Recent trends towards service orientation make manufacturing, especially in developed economies, to move into a more service oriented strategy. One solution is to fulfill customer requirements by a product and its after-sales services. However, the actual impact of this transformation on manufacturers has never been explored. This study aims to understand how evolution of service in terms of service-width and length takes place over time, and how it impacts on the manufacturer and is impacted from it. We carry out a longitudinal case-based study on a particular service family (iTune) in consumer electronics using Pearson correlation and linear regression using SPSS software package. Considering consistent intention to improve existing ones and introduce new services, following results are gained: (1) Manufacturing with higher research and development capabilities are expected to have great potential to have strong after-sales portfolio both in terms of service-width and length. A strong portfolio in this type of manufacturing is expected to bring economic advantage. (2) Manufacturing with higher liabilities is expected to have more economic advantage in increasing service-width. (3) Manufacturing with robust infrastructure are expected to have more economic advantage in increasing service-length.
A Multi-Level Approach to Concept Selection in Sustainable Design
Authors: Stratton Daniel , Behdad Sara , Lewis Kemper , Krishnamurty Sundar
Published: January 2015

The motivation behind this work is to integrate economic and environmental sustainability into decision making at the early phases of design through the development of a hierarchical concept selection method. Life Cycle Assessment (LCA) is a frequently implemented technique used to assess the environmental impacts of products, but it does not provide a simple means for including preference at different levels that can be used for comparison across design alternatives. A method is proposed to accommodate this issue expanding the Hypothetical Equivalents and Inequivalents Method (HEIM) to handle multi-level and multi-attribute trade-offs. The selection of a coffee maker design is used as an example to illustrate the implementation of the method with actual LCA results. The example provides valuable insights into how preferences may be elicited at different hierarchical levels and then combined to create a single utility score that represents to what extent each design alternative is preferred by the decision maker.
Words or Images: Insights on How Engineering Students and Engineers Communicate in Practice
Authors: Bairaktarova Diana , Pilotte Mary
Published: January 2015

This paper examines the use of language (text and verbal communication) across school and work settings. The participants of the study are from two distinct pools — 380 first-year engineering students and 355 industry professionals. To test the study predictions and interpret the results the individual data sets from both studies were reviewed and analyzed. Data suggests that for the professional engineering population, face to face communication was the preferred communication mode for sharing engineering evaluation, communicating difficult concepts, and describing their work product. Email and file sharing were also utilized communication options, but to a lesser extent. Data from students facing a simulated professional assignment (produce a fabrication instruction for assembling a mechanical object) indicated that 94% of the students’ chose to use language to produce fabrication instructions, compared to only 6% of students who used another tool of engineering representation in the form of sketches. Data investigation and outcomes are discussed in terms of prevalence and importance of language in engineering education.
Energy Harvesting From Controlled Buckling of a Horizontal Piezoelectric Beam
Authors: Ansari M. H. , Karami M. Amin
Published: January 2015

A piezoelectric vibration energy harvester is designed to generate electricity under the weight of passing crowds. The piezoelectric beam buckles to a controlled extent when the device is stepped on. The device is a seven bar mechanism. The upper and lower bars as well as the lateral links are rigid. The middle horizontal beam is a bimorph piezoelectric beam. Damages to the piezoelectric beam are avoided by constraining its axial deformation. This constrain is implemented by limiting squeezing of the mechanism. When a person moves over the mechanism or steps off the devices it causes the bimorph to buckle or return to the unbuckled condition. The transitions result in vibrations of the piezoelectric beam and thus generate energy.

In this paper, the energy harvester is analytically modeled. The electro-mechanical coupling and the geometric nonlinearities have been included in the model for the piezoelectric beam. 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 of power. A three part beam is also investigated. The effect of design parameters on the generated power and required tolerances are illustrated.

The proposed device could be implemented in the sidewalks producing energy from the weight of people passing over it. Other possible applications are portable smart phones chargers and shoe hill energy harvesting. Dance floor of a club is another applicable example for using this harvester. The main advantage of using horizontal configuration instead of a vertical arrangement is the ease of placement in the pavements.
Dynamics and Control of the Bucket-Wheel Excavator: Part II — Vibration Control of Bucket-Wheel Boom
Authors: Luu Quang Khanh , Söffker Dirk
Published: January 2015

Bucket-Wheel excavators (BWE) represent a specific type of complex machine system used in mining technology. During operation, the system is exposed to a number of external forces and disturbances like digging resistances on the Bucket-Wheel that cause transverse, longitudinal, and torsional vibrations. All vibrations will be affected to normal working conditions, operational effectiveness, and may under specific conditions also effect the stability of the BWE. Taking into account nonlinear effects due to the higher-order geometrical and dynamical couplings of flexible deformations modeled under guided motions in combination with digging resistance forces result to the adequately dynamic behavior of the Bucket-Wheel boom, introduced in the first part. Additionally, it also leads to difficulties controlling the nonlinear dynamic system. To overcome these difficulties here the nonlinear dynamical system is approximated by an equivalent linear system linearized for suitable working points of remaining and not considered additive nonlinear parts of the system. In this contribution, based on the nonlinear characteristic of the system, the time behavior of nonlinearities (as additive effects in relation to the linearized system) is estimated in combination with related system states using a high-gain extended state observer. Then the well-known disturbance rejection control approach is used for vibration control of this nonlinear mechanical system. Simulation examples are included to illustrate the efficient suppression of vibrations as well as stabilization of the system during the digging process of Bucket-Wheel Excavator.
Library of T-Maps for Dimensional and Geometric Tolerances
Authors: Rao Shyam S. , Haghighi Payam , Shah Jami J. , Davidson Joseph K.
Published: January 2015

Tolerances are specified by a designer to allow reasonable freedom by a manufacturer for imperfections and inherent variability without compromising performance. T-Map is a hypothetical Euclidian point space model which describes all possible variations constrained by design or machining tolerances. The size and shape of T-Map reflects all variational possibilities for a target feature. According to ASME Y14.5M standard, tolerances are dimensional or geometric, and geometric tolerances are divided into different classes. T-maps have been created for all types of geometric tolerances with Primitive T-Map Elements. In this paper we have reviewed the basic ideas of T-maps, the reason it has been built, and the contribution it can have in design and manufacturing. It is then followed by a library of T-maps created for all Tolerance classes with brief description for each one.
Collaborative Design Principles From Minecraft With Applications to Multi-User CAD
Authors: French David J. , Stone Brett , Nysetvold Thomas T. , Hepworth Ammon , Red W. Edward
Published: January 2015

Real-time simultaneous multi-user (RSM) computer-aided design (CAD) is currently a major area of research and industry interest due to its potential to reduce design lead times and improve design quality through enhanced collaboration. Minecraft, a popular multi-player online game in which players use blocks to design structures, is of academic interest as a natural experiment in collaborative 3D design of very complex structures. Virtual teams of up to forty simultaneous designers have created city-scale models with total design times in the thousands of hours. Using observation and a survey of Minecraft users, we offer insights into how virtual design teams might effectively build, communicate, and manage projects in an RSM CAD design environment. The results suggest that RSM CAD will be useful and practical in an engineering setting with several simultaneous contributors. We also discuss the potential effects of RSM CAD on team organization, planning, design concurrency, communication, and mentoring.
Are You Haptic a Bad Day?
Authors: Lim Theodore , Badillo Germánico González , Castillo Hugo I. Medellín
Published: January 2015

As with any haptic application development, issues of performance are often the subject of discussion (or contention) after design is already completed. Evaluating haptic-based applications have largely focused on a combination of qualitative and quantitative analysis of kinesthetic feedback, repeatability of haptic task responses and/or the correlation of visualization software and haptic rendering, to name but a few. However, while there are ISO guidelines to evaluate the ergonomics of human system interaction, particularly in the area of usability, there is little resource in way of code diagnostics of haptic application architectures. This paper proposes a methodology of profiling for haptic applications as a measure of operational criteria. It is hoped that the findings and suggestions made can further advance the evaluation and development of more robust haptic systems.