bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermodynamic Variational Formulations of Subordinate Oscillator Arrays (SOA) With Linear Piezoelectrics
Authors: Paruchuri Sai Tej , Kurdila Andrew J. , Sterling John , Vignola Amelia , Judge John , Vignola Joe , Ryan Teresa
Published: November 2017

It has been shown theoretically that by prescribing the mass and stiffness distributions of a subordinate oscillator array (SOA) that is attached to a host structure, significant vibration attenuation of a host can be obtained over a finite frequency range. This case stands in stark contrast to classical vibration isolator designs for two degree of freedom systems that achieve exact vibration cancellation at a single isolated frequency. Despite the attractiveness of SOAs for the design of broader band vibration suppression, the theoretically desired result can deteriorate rapidly due to small fabrication imperfections in the SOA. This paper introduces and compares variational thermodynamic formulations of composite piezoelectric SOA that are designed to be adjustable in real-time to ameliorate the effects of disorder due to fabrication in a SOA.
Copula-Based Time-Frequency Distribution Analysis for Planetary Gearbox Fault Detection
Authors: Liu Libin , Zuo Ming J.
Published: November 2017

Linear and bilinear time-frequency distributions (TFDs) have been employed in planetary gearbox fault diagnosis. For linear TFDs, there is a trade-off between the time localization and frequency resolution and the spectrogram may not have correct energy marginals. For bilinear TFDs, they cannot be interpreted as an energy distribution because of the existence of possible negative values even though they are designed for energy density representation. To overcome these shortcomings, TFDs based on copula theory have been reported in the literature. In this paper, we analyze two simulated data sets using linear TFD and copula-based TFD. The results show that the constructed copula-based TFD has desirable properties of being positive, free from cross-term interference, having high time-frequency resolution and matching well with true marginals. The copula-based TFD is also able to locate fault-induced impulses by vertical lines over a certain frequency range in the time-frequency domain. Consequently, this study confirms the advantages of the copula-based TFD as an energy distribution and its capability in fault detection for planetary gearboxes.
Analytical and Experimental Investigation of a Passively Controlled Infinitely Variable Positive Displacement Water Pump
Authors: Mullen John , Cyders Timothy J.
Published: November 2017

A passively controlled infinitely variable transmission modeled and experimentally investigated by Cyders (2012), has potential to be combined with a number of different types of mechanisms. The mechanism’s incorporation into a hydraulic pump has many applications of interest; the CVT approach to a positive-displacement pump could provide a combination of the advantages of both positive-displacement and centrifugal pumps in one machine. This work had two main objectives: first, an inverse dynamic analytical model was developed using piece-wise techniques that simulated the behavior of the CVT/PD pump system. Second, this simulation was compared against experimental results, which were generated from data taken from an example system prototype. Predictions were made using an inverse-dynamics model, and were compared against experimental findings generated from a prototype of the system. The simple approach to modeling provided results sufficient to describe the overall pressure-flowrate behavior of the pump at low speeds, but a more sophisticated dynamic approach is still necessary to improve model agreement at high speeds when second-order effects begin to dominate.
Nonlinear Response Compensation of Flexure-Hinge Based Guiding Mechanism Using Bi-Linear Control Input
Authors: Yang Zhijun , Bai Youdun , Chen Xin
Published: November 2017

The flexure-hinge (FH) based guiding mechanism, such as fast tool servo (FTS) or micro-lens-array punching machine, is widely used in micro/nano precision engineering, due to their good linearity of stiffness. The major design advantage of FHs for this application was the absence of backlash and friction in the direction of the motion. This provides very smooth, high-precision operating characteristics without inducing evident wear which is commonly associated with high speeds or continuous operation. The dynamic model of FH can be simplified as a spring-mass-damping system, both the stiffness and frequency of a mechanism play significant roles in its dynamic performance. However, the relationship between dynamic response and the input function is nonlinear. In order to achieve precision displacement output under different excitation frequency, nonlinear input compensation should be considered. In this paper, an innovative method is provided to handle this kind of problem, where the stiffness of the guiding mechanism can be adjusted, such that the output amplitude scale can be remained the same at any excitation frequency, therefore, it become a linear system, the input is very easy to control. The tension stiffening is used to change the stiffness and thus the frequency, and the relationship between the change rate of frequency and tension force is also revealed. Finally, the control strategy is given, and an example is given to show the efficient of the presented method.
Micro Power Multiplexer, a Compact Device That Controls Mechanical Power Flow
Authors: Zhang Xiaoguang , Hong Dennis W.
Published: November 2017

A novel device that we have named Micro Power Multiplexer was developed. The goal of this work was to create a device that can split one power input to several outputs with controllable distribution while providing high modularity, robustness, and compactness. This device is capable to greatly reduce the size, weight, and complexity of a mechanical system requiring complicated distribution of mechanical power.

To reduce friction and provide robustness, a device with “mechanical intelligence” named Non-Contact Flexure was designed. Non-Contact Flexure and a clutching mechanism for this device was theoretically modeled and are discussed in this paper. A zero-load prototype was built to test the design. The effect of main shaft and shift speed was studied during dynamic shifting experiments. Shifting with zero main shaft speed was also tested. The device was proven to be stable and robust. This paper further discusses in detail the various test results obtained.
Complexity Criteria for the Preliminary Design Stage of Walking Robots
Authors: Xi Da , Gao Feng
Published: November 2017

This paper introduces several complexity-based criteria for walking robots at the preliminary design stage. The motivation lies in filtering optimal leg types or body layouts to reduce cost at later iterative-design stage. Several qualitative or semi-quantitative criteria are proposed for walking robot designers. For different type-synthesis results of robot legs, three criteria are proposed named the uncertainty of the end-effector, the complexity of control and the complexity of movement. For different layouts of robot bodies, two kinematic criteria are proposed named the complexity of translation and the complexity of rotation. These criteria could together judge the kinematic performance or potential for a walking robot with the least structure parameters at the conceptual-design stage. Several prototypes in the researchers’ lab are evaluated with the criteria, and the results are compared with the experimental data to proof the validity.
Finite Element Modeling of Stockbridge Damper and Vibration Analysis: Equivalent Cable Stiffness
Authors: Vaja Nitish Kumar , Barry Oumar , DeJong Brian
Published: November 2017

Aeolian vibrations are the major cause for the failure of conductor cables. Using a Stockbridge damper reduces these vibrations and increases the life span of the conductor cable. Designing an efficient Stockbridge damper that suits the conductor cable requires a robust mathematical model with minimum assumptions. However it is not easy to analytically model the complex geometry of the messenger. Since, the messenger is a bunch of thin helical wires with nonlinear contact conditions. Therefore an equivalent stiffness must be determined so that it can be used in the analytical model. This paper examines the bending stiffness of the cable and discusses the effect of this stiffness on the natural frequencies. The obtained equivalent stiffness compensates for the assumption of modeling the messenger as a rod. The results from the free vibration analysis of the analytical model with the equivalent stiffness is validated using the full scale finite element model of the Stockbridge damper.
Lifecycle Tools As a Support for the Eco-Design Innovation of Domestic Appliances
Authors: Papetti Alessandra , Germani Michele , Marconi Marco , Favi Claudio
Published: November 2017

The goal of sustainable development through the product innovation is a global challenge that Academia and Industries are addressing. The regulatory pressure and the growing demand of eco-friendly products by consumers are two of its main drivers, especially in the household appliances sector. For this aim, manufactures need to change the design approach in order to extend the boundaries of the benchmark analysis of possible innovations: (i) multi-objective criteria should be taken into account such as the environmental issues, costs, technical performances, etc., and (ii) a life cycle thinking has to be adopted to consider long terms benefits or impacts.

However, the literature highlights the lack of structured methods able to support the R&D activity according to these perspectives. For this aim, the present paper provides a systematic approach, which exploits lifecycle and innovation tools to effectively support designers in the development of sustainable solutions in a long term perspective. The proposed approach has been applied in real case study to increase the energy efficiency of a domestic refrigerator. In particular, the insulation module has been redesigned by comparing several alternatives in terms of environmental performances and costs over the product lifespan to effectively evaluate the consistency of the developed eco-innovations.
Exploration of Solution Space to Study Thermo-Mechanical Behavior of AA5083 Al-Alloy During Hot Rolling Process
Authors: Nellippallil Anand Balu , Shukla Rishabh , Ardham Surya , Goh Chung-Hyun , Allen Janet K. , Mistree Farrokh
Published: November 2017

A method is proposed to explore the solution space of a metallurgical process with an aim to foster material innovation through simulation based design. The efficacy of the method is demonstrated in the context of hot rolling of the AA5083 alloy. The set-based design approach is employed to predict the process parameters of rolling operation for a given set of specified requirements. Critical process parameters such as strain rate, temperature, heat transfer coefficient and strip width are only considered in the design study. Ternary plots are constructed and utilized to explore the solution space obtained and thereby identifying feasible regions of process operation wherein the specified requirements are satisfied. Since plant data is not available for the study, Finite-element (FE) analysis is carried out as a means to validate the results obtained using aforesaid design method.
Angular Positioning and Vibration Control of a Slewing Flexible Control by Applying Smart Materials and Sliding Modes Control
Authors: Janzen Frederic C. , Balthazar Jose M. , Tusset Angelo M. , Rocha Rodrigo T. , Jose de Lima Jeferson
Published: November 2017

Flexible links undergoing a slewing motion are widely found in aerospace structures such as satellites and robotic manipulators. In this kind of systems, the lighter the structure the better is its performance and more cost effective is the system. However, the positioning control of flexible structures is challenging because the flexibility may lead the system to vibrate in larger amplitudes, which makes the need of using actuators to control and reduce vibrations. An alternative for those actuators is the use of smart materials, as SMA (Shape Memory Alloys) to control vibrations of such structures. This work will present the angular positioning and vibration control of a flexible link. The angular position control is a torque driven by a DC motor controlled through a sliding modes control method. The system is considered as non-ideal, it means that the vibration of the flexible link accomplishes to the DC motor shaft. SMA actuators are coupled to the flexible link with the objective to reduce the vibration amplitudes and reducing so the settling time of the system. The SMA actuators are controlled through an electric voltage applied to its terminals by applying the Sliding modes control method. The dynamical equations of motion for the system are developed considering a dead zone nonlinearity of the DC motor and a phenomenological model for the SMA. The flexible link is modeled as a continuous structure and just the first vibration mode is analyzed. Numerical simulations results are presented to demonstrate the effectiveness of the sliding modes strategy for the positioning control of the DC motor and for the vibration suppression of the flexible link by using SMA actuators.
Can Wearable Sensors Be Used to Capture Engineering Design Team Interactions?: An Investigation Into the Reliability of Sociometric Badges
Authors: Chen Hong-En , Miller Scarlett R.
Published: November 2017

Engineering organizations around the word are increasingly becoming team-based due to a teams’ ability to generate solutions to complex problems. This is thought to be attributed to the “wisdom of the collectives” where teams outperform the sum of their individual members. Despite heavy emphasis of teamwork in engineering design, our understanding of how to cultivate teamwork skills is poorly understood. This is due in part to the fact that research on engineering design teams is often based on ‘snap-shot’ ethnographic methods that do not account for the dynamic changes that happen over the course of a project. Research that does account for these interactions are hindered by the human processing required to code and analyze the immense amounts of video data acquired through team studies. Recent technological advances in the way of sociometric badges provide a potential avenue to explore intricate communication patterns and help researchers identify when and how team interventions should be developed. However, these technologies have not been validated for use in the dynamic context of engineering design teams. Thus, the current study was developed to examine sociometric badges for their accuracy, precision, and ability to determine speech dominance in engineering design teams. Our results show that sociometric badges can accurately capture total speaking time. However, the results also show that environmental conditions can impact their accuracy. In addition, we found that sociometric badges did not capture speech precisely and often overestimated when a team member was speaking. These results support the use of sociometric badges for capturing high level team interactions (e.g. participation and total speaking time) in engineering design research.
A Pressure Modulating Sensorized Soft Actuator Array for Pressure Ulcer Prevention
Authors: Carrigan Wei , Nuthi Pavan , Pande Charu , Nothnagle Caleb P. , Wijesundara Muthu B. J.
Published: November 2017

Pressure ulcers are a serious reoccurring complication among wheelchair users with impaired mobility and sensation. It is postulated that external mechanical loading, specifically on bony prominences, is a major contributing factor in pressure ulcer formation. Prevention strategies mainly center on reducing the magnitude and duration of external forces acting upon the body. Seat cushion technologies for reducing pressure ulcer prevalence often employ soft materials and customized cushion geometries. Air cell arrays used in time-based pressure modulation techniques are seen as a promising alternative; however, this approach could be further enhanced by adding real-time pressure profile mapping to enable automated pressure modulation customizable for each user’s condition. The work presented here describes the development of a prototype support surface and pressure modulation algorithm which can monitor interface pressure as well as automatically offload and redistribute concentrated pressure. This prototype is comprised of arrays of sensorized polymeric soft air cell actuators which are modulated by a pneumatic controller. Each actuator’s pressure can be changed independently which results in a change to the interface pressure allowing us to offload targeted regions and provide local adjustment for redistribution. The pressure mapping, redistribution, and offloading capabilities of the prototype are demonstrated using pressure modulation algorithms described here.
Incorporating Manufacturing Constraints in Topology Optimization Methods: A Survey
Authors: Sutradhar Alok , Park Jaejong , Haghighi Payam , Kresslein Jacob , Detwiler Duane , Shah Jami J.
Published: November 2017

Topology optimization provides optimized solutions with complex geometries which are often not suitable for direct manufacturing without further steps or post-processing by the designer. There has been a recent progression towards linking topology optimization with additive manufacturing, which is less restrictive than traditional manufacturing methods, but the technology is still in its infancy being costly, time-consuming, and energy inefficient. For applications in automotive or aerospace industries, the traditional manufacturing processes are still preferred and utilized to a far greater extent. Adding manufacturing constraints within the topology optimization framework eliminates the additional design steps of interpreting the topology optimization result and converting it to viable manufacturable parts. Furthermore, unintended but inevitable deviations that occur during manual conversion from the topology optimized result can be avoided. In this paper, we review recent advances to integrate (traditional) manufacturing constraints in the topology optimization process. The focus is on the methods that can create manufacturable and well-defined geometries. The survey will discuss the advantages, limitations, and related challenges of manufacturability in topology optimization.
A Case Study of the Effects of Design Project Length on Team Collaboration and Leadership in Senior Mechanical Engineering Projects
Authors: Righter James , Blanton Andy , Stidham Hallie , Chickarello Doug , Summers Joshua D.
Published: November 2017

This paper describes exploratory research regarding leadership and communication within undergraduate engineering design teams. The case study was performed on student design projects of one and two semester duration to begin to assess the impact of project length on leadership and communication within the design teams. Data was collected using a survey that was given to the participants in three capstone design projects in Clemson University’s senior design course. The survey was administered within one month of course and project completion. While there were differences in the communication and leadership patterns between the teams, there were other possible influences beyond the project length such as team size and organization, organizational and geographic distribution, and the nature of the product. As a result, further research is proposed to study leadership and communication structures within undergraduate teams and multi-team systems (MTS).
Cooperative Brake Control Strategy for Electric Vehicle Equipped With a Two-Speed Uninterrupted Mechanical Transmission
Authors: Tai Yuzhuo , Song Jian , Yu Liangyao , Fang Shengnan , Nguyen Truong Sinh
Published: November 2017

Regenerative braking of EV (electric vehicle) can enhance fuel efficiency to a great extent in urban areas. In addition, transmission plays a great role on the vehicle fuel economy and comfort and there are some research focus on the multi-speed transmission on EV. However, only limited number of scholars discussed about the influence of multi-speed transmission system on regenerative braking system. This paper focus on the effects of Electric Vehicle equipped with a Two-speed Uninterrupted Mechanical Transmission., which consist of a set of planetary gear, band brake and friction clutch. The transmission is capable of achieving seamless downshift which indicates that it can still transfer torque while downshifting. At the same time, as traction interruption of shift exerted an influence on the comfort during brake, this article put forward with a cooperative control algorithm considering the real response of electrohydraulic braking system in order to compensate the traction interruption and established an dynamic simulation model to testify the algorithm. The transmission dynamic model is developed by utilizing Euler-Lagrange equations to derive the motion while the other models are some simplified models. The whole model is applied by using the SimDriveline library of the MATLAB/Simulink. The simulation results of EV which commit a downshift while brake and the EV keep the gear are compared at the last demonstrate that the downshift strategy can save more energy without excessive oscillations.
On the Effects of Temperature and Relative Humidity on the Response of a MEMS Arch Resonator
Authors: Hasan Mohammad H. , Ouakad Hassen M. , Alsaleem Fadi
Published: November 2017

In this paper, we present a comprehensive model to simulate the behavior of a general MEMS arch resonator under various thermal conditions. The model takes into account the changes in the microbeam’s parameters, air properties and the internal stresses due to temperature and humidity. The continuous, flexible, initially curved microbeam was excited linearly and nonlinearly around both its first and third modal natural frequencies. It was found that the mutual effects of temperature and humidity on air viscosity is amplified over four times when the microbeam is operated in the nonlinear regime. Furthermore, results showed that the relative humidity influence is more severe at higher values of the temperature. Finally, the microbeam’s frequency shift due to change in humidity increases when operating the microbeam at its third natural frequency compared to first natural frequency.
Effect of Unbalance Force Direction on a Cracked Rotor Whirl Response
Authors: Al Hosani Hanan , AL-Shudeifat Mohammad A. , Saeed Adnan S. , Balawi Shadi
Published: November 2017

The combined effect of the crack and the unbalance force vector angle on the values and locations of the whirl amplitudes at the critical whirl speeds for a cracked rotor-bearing-disk system is numerically and experimentally investigated here. The strongly nonlinear time-periodic equations of motion, which are analogous to Mathieus equation, of the cracked system with an open crack model are formulated according to the finite element time-periodic stiffness matrix. The whirl response during the passage through the critical speeds is obtained via numerical simulation for different unbalance vector angles with respect to the crack opening direction. It is found that the variation in the unbalance force vector angle with respect to the crack opening direction significantly alters the peaks of the critical whirl amplitudes and their corresponding critical whirl speeds. Consequently, the critical speeds of the cracked rotor are either shifted to higher or lower values according to the unbalance force vector angle value. These significant numerical simulation observations are also verified via robust experimental results.
High-Dimensional Reliability Analysis of Engineered Systems Involving Computationally Expensive Black-Box Simulations
Authors: Sadoughi Mohammad Kazem , Li Meng , Hu Chao , Mackenzie Cameron A.
Published: November 2017

Reliability analysis involving high-dimensional, computationally expensive, highly nonlinear performance functions is a notoriously challenging problem. In this paper, we tackle this problem by proposing a new method, high-dimensional reliability analysis (HDRA), in which a surrogate model is built to approximate a performance function that is high dimensional, computationally expensive, implicit and unknown to the user. HDRA first employs the adaptive univariate dimension reduction (AUDR) method to build a global surrogate model by adaptively tracking the important dimensions or regions. Then, the sequential exploration-exploitation with dynamic trade-off (SEEDT) method is utilized to locally refine the surrogate model by identifying additional sample points that are close to the critical region (i.e., the limit-state function) with high prediction uncertainty. The HDRA method has three advantages: (i) alleviating the curse of dimensionality and adaptively detecting important dimensions; (ii) capturing the interactive effects among variables on the performance function; and (iii) flexibility in choosing the locations of sample points. The performance of the proposed method is tested through two mathematical examples, the results of which suggest that the method can achieve accurate and computationally efficient estimation of reliability even when the performance function exhibits high dimensionality, high nonlinearity, and strong interactions among variables.
Fusion Clutch: A Bi-Stable Latching Mechanism for Human-Safe Robots
Authors: Cochran Jillian C. , Hong Jimin , Dollar Aaron M.
Published: November 2017

As the role of robotics continues to expand beyond highly structured manufacturing applications to other domains, including medical and service applications, safe operation in the presence of people is becoming increasingly important. Many existing safety systems rely on fragile and sophisticated joint torque sensors and control models that greatly add to the expense and complexity of the robot system. This paper presents the “Fusion Clutch”, a mechanical system for decoupling high-impedance actuators from the output, such as a robot arm, in the event of a collision. In its nominal configuration, the clutch couples the transmission to the output via a spring-loaded bi-stable mechanism that is able to quickly decouple the two in the event of a collision with very low activation force. After the actuator is disengaged, the clutch also applies a brake to the output that prevents it from falling under the force of gravity but allows the operator to still reposition it. This prevents a robot arm from pinning the operator after the mechanism had been activated. Experimental results validate the small force required to activate the mechanism, along with a substantial decrease in force impulse during impact.
Axially Modulated Clamped-Guided Arch Resonator for Memory and Logic Applications
Authors: Hafiz Md Abdullah Al , Tella Sherif , Alcheikh Nouha , Fariborzi Hossein , Younis Mohammad I.
Published: November 2017

We experimentally demonstrate memory and logic devices based on an axially modulated clamped-guided arch resonator. The device are electrostatically actuated and capacitively sensed, while the resonance frequency modulation is achieved through an axial electrostatic force from the guided side of the clamped-guided arch microbeam. We present two case studies: first, a dynamic memory based on the nonlinear frequency response of the resonator, and second, a reprogrammable two-input logic gate based on the linear frequency modulation of the resonator. These devices show energy cost per memory/logic operation in pJ, are fully compatible with CMOS fabrication processes, have the potential for on-chip system integration, and operate at room temperature.
Dynamic Analysis of an Elevator Traveling Cable Using a Singularity-Free Beam Formulation
Authors: Fan W. , Zhu W. D.
Published: November 2017

An elevator traveling cable is modeled using a singularity-free beam formulation and its static and dynamic behaviors are analyzed. The beam is assumed to be an extensible Euler-Bernoulli beam, and the configuration of the beam is described by Euler parameters, which can resolve the singularity problem of Euler angles, and the normal strain of the centroid line of the beam. The position of the centroid line of the beam is integrated from its slope. Governing equations of the beam and constraint equations are derived using Lagrange’s equations for systems with constraints. The current formulation is used to calculate the equilibrium and dynamic responses of an elevator traveling cable with arbitrarily moving ends. Equilibria of a traveling cable with different elevator car positions are calculated. Natural frequencies and corresponding mode shapes of the traveling cable are calculated and they are in excellent agreement with those calculated by ABAQUS. In-plane natural frequencies of the traveling cable do not change much with the car position compared with its out-of-plane ones. Dynamic responses of the traveling cable are calculated using the current formulation and compared with those from commercial multibody dynamics software RecurDyn, and they are in good agreement with each other. Free responses of the traveling cable due to vertical motion of the car and forced responses with inplane and out-of-plane building sways are simulated, and their effects on dynamic responses of the traveling cable are investigated. While the vertical motion of the car can affect the in-plane lateral response of the traveling cable, it has almost no effect on its out-of-plane response. Building sways can affect both lateral and out-of-plane responses of the traveling cable, but they have little effect on its vertical response.
Designing Sustainable Manufacturing Networks: The Role of Exclusive Species in Achieving Ecosystem-Type Cycling
Authors: Layton Astrid , Bras Bert , Weissburg Marc
Published: November 2017

Ecology is proving to be an innovative source for design principles. Studies have examined how ecological principles can enhance sustainability in industrial networks. Ecologically-inspired manufacturing networks tend to focus on supporting symbiotic relationship formation, creating a cyclical flow structure that has been shown to result in efficiency and resource consumption improvements. Despite successes, bio-inspired manufacturing networks still fail to accurately mimic ecosystem cycling. The roles of exclusive actors and specialized predators in achieving the high cycling characteristic of ecosystems is investigated here. Exclusive actors participate in the network as either only a consumer (predator) or only a producer (prey). Specialized predators consume only one producer inside the system boundary. The populations of these special actors in manufacturing networks versus ecological food webs speaks to the potential influence these roles have on the cycling the network achieves. The trends shown here suggest less exclusivity is necessary for achieving ecologically-strong network cycling.
A Study on Finding Finite Roots for Kinematic Synthesis
Authors: Plecnik Mark M. , Fearing Ronald S.
Published: November 2017

This study presents new results on a method to solve large kinematic synthesis systems termed Finite Root Generation. The method reduces the number of startpoints used in homotopy continuation to find all the roots of a kinematic synthesis system. For a single execution, many start systems are generated with corresponding startpoints using a random process such that start-points only track to finite roots. Current methods are burdened by computations of roots to infinity. New results include a characterization of scaling for different problem sizes, a technique for scaling down problems using cognate symmetries, and an application for the design of a spined pinch gripper mechanism. We show that the expected number of iterations to perform increases approximately linearly with the quantity of finite roots for a given synthesis problem. An implementation that effectively scales the four-bar path synthesis problem by six using its cognate structure found 100% of roots in an average of 16,546 iterations over ten executions. This marks a roughly six-fold improvement over the basic implementation of the algorithm.
C-STEM Studio: A Solution for Learning Computing and STEM Topics With Robotics and Embedded Systems
Authors: Qian Binsen , Cheng Harry H.
Published: November 2017

In this article, C-STEM Studio, a platform for hands-on integrated learning of Computing, Science, Technology, Engineering and Mathematics (STEM) with robotics, is presented. C-STEM Studio integrates many technologies, software, and curriculum that K-12 educators can use in their classroom. Ch, a C/C++ interpreter, provides an environment for computing. Linkbot Labs, Ch Linkbot Controller, and Ch Robot Controller allow teachers to utilize the robotics, such as Linkbots and Lego Mindstorms NXT and EV3, to help teach concepts in mathematics and science. RoboSim and RoboBlockly are simulation environments that allow students without physical robots to learn with virtual robots. Teachers can also teach embedded systems with Ch Arduino package, designed atop Ch. Also, easy-to-use resources explorers are built in the C-STEM Studio so that teachers and students can access teaching resources, students homework and materials come with those software. Finally, we provided a solution for Chromebook users to run C-STEM Studio through Raspberry Pi.
Optimization Under Uncertainty Versus Algebraic Heuristics: A Research Method for Comparing Computational Design Methods
Authors: Binder William R. , Paredis Christiaan J. J.
Published: November 2017

In this paper, we introduce a research method for comparing computational design methods. This research method addresses the challenge of measuring the difference in performance of different design methods in a way that is fair and unbiased with respect to differences in modeling abstraction, accuracy and uncertainty representation. The method can be used to identify the conditions under which each design method is most beneficial. To illustrate the research method, we compare two design methods for the design of a pressure vessel: 1) an algebraic approach, based on the ASME pressure vessel code, which accounts for uncertainty implicitly through safety factors, and 2) an optimization-based, expected-utility maximization approach which accounts for uncertainty explicitly. The computational experiments initially show that under some conditions the algebraic heuristic surprisingly outperforms the optimization-based approach. Further analysis reveals that an optimization-based approach does perform best as long as the designer applies good judgment during uncertainty elicitation. An ignorant or overly confident designer is better off using safety factors.
Discrimination of Multiple Faults in Bearings Using Density-Based Orthogonal Functions of the Time Response
Authors: Haj Mohamad T. , Kitio Kwuimy C. A. , Nataraj C.
Published: November 2017

This study investigates the use of the mapped density of time response using orthogonal functions to detect single and multiple faults in rolling element bearings. The method is based on constructing the density of a single time response of the system by using orthogonal functions. The coefficients of the orthogonal functions create the feature vector in order to discriminate between different rolling element bearing faults. The method does not require preprocessing of the data, noise reduction, or feature selection. This method has been applied to vibration data of different bearing conditions at rotational speeds ranging from 300 rpm to 3000 rpm. These conditions include a healthy bearing, and bearings with defects in inner race, outer race, combination of inner race and outer race and rolling element. The results have shown remarkable detection efficiency in the case of a single and two bearing fault configurations. In general, for all bearing configurations, the approach has high performance in detecting defective conditions. These results indicate that using the mapped density to characterize the system under different conditions has considerable potential in bearing diagnostics.
The Design and Manufacture of a Gear-Coupled Serial Chain to Trace the Butterfly Curve
Authors: Liu Yang , Wang Peter Lee-Shien , McCarthy J. Michael
Published: November 2017

This paper presents a design and manufacturing methodology for a mechanical system that draws trigonometric curves assembled from a series of links connected by gears. We demonstrate this technique using 11 gear-coupled links that trace a butterfly curve. The equation of a butterfly curve is converted to the relative rotations of the links of a coupled serial chain assembled so it operates with one input. We present a procedure to determine the adjustments to the gear ratios and link dimensions necessary for practical manufacture of the mechanism. The results are demonstrated by a working prototype.
Application of T-Maps for Composite Position Tolerance for Patterns of Features
Authors: Ameta Gaurav , Singh Gagandeep , Davidson Joseph K. , Shah Jami J.
Published: November 2017

The purpose of this paper is to develop Tolerance-Maps (T-Maps) for composite position tolerance applied to patterns (arrays) of features. The T-Map (Patent No. 6963824), is a range of points obtained by mapping all the variational possibilities of a feature within its tolerance-zone to a hypothetical Euclidean point space. T-Maps have already been developed for tolerances applied to features, such as a simple axis (line), a plane, a cylinder, etc., but not for patterns of features. In this paper, the developed T-Map model will be shown to be sensitive to the effects of composite position tolerance, two-single segment control frames and material modifiers. Two levels of T-Maps are proposed for a pattern of features: assembly level (ensuring assembly of engaging pattern of features) and part level (map of variations of entire pattern as a whole). The use of assembly level and part level T-Map is demonstrated with a pattern of features. The pattern of features considered is two-dimensional patterns of pins and holes that are intended to engage (e.g. an integrated circuit and its plug-in base).
A Framework for Wind Energy Conversion to Promote Sustainability in Product Design
Authors: Ball Zachary , Szabo Joe , Pasquali Felipe M. , Hall John F.
Published: November 2017

This paper presents a sustainable design method for wind turbines. Sustainable design recognizes three main pillars; economic growth, social equity, and environmental protection. A framework is developed to observe the tradeoffs among these areas of sustainable design. Each pillar of sustainability is mapped to a design variable, and normalized objective functions are defined. For the economic component, the objective function is based on costs and power production. The societal objective function focuses on noise and aesthetics impacts. These are represented by risk averse utility functions. Carbon dioxide emissions and noise pollution are the environmental objectives. A multi-objective genetic algorithm is also used with Pareto optimality to identify tradeoffs between these three sustainability factors. Wind speed data from three sites is used to simulate the performance of the system. The sets of data are unique and represent low, medium, and high wind speed areas. In all three cases, the results indicate that the economic and environmental objectives can both be met with a relatively small tradeoff. However, a greater amount of tradeoff is necessary when considering societal impacts.
The Social Impact of STEM, Experienced: Studies With an Engineering Design Concept for Smart Devices
Authors: Nietner Larissa F. , Wallace David R.
Published: November 2017

The government has been allocating multi-billion Dollar budgets to STEM (science, technology, engineering and math) education. Several programs aim to educate girls about STEM and STEAM (STEM and arts). It’s a national goal to create equal opportunities for all genders and increase diversity in STEM fields.

We propose that the emerging values and social needs of middle school girls must be considered when creating learning experiences for them, and that appropriate design experiences can make engineering problems engaging and relatable. It has been shown that purposefulness is a critical factor for making engineering attractive to girls. Compared to boys, girls initially perceive engineering to be less socially impactful, yet girls place a higher value on social impact at an earlier age.

This paper provides a broad review of relevant literature. It is proposed that creative, innovative engineering activities with perceived social impact may motivate middle and high school girls and build their confidence in the ability to impact people’s lives with technology they create. This work tests this hypothesis using different forms of a design activity that enables students to collaboratively build personal and wearable smart devices. Examples of creations based upon this design toolkit include medical bracelets, physical activity monitoring, and other devices.

The paper outlines the development of the toolkit and design activity through various stages of abstraction, and provides novel ways of prototyping design experiences. Three stages of development are implemented and tested with adolescent girls, offering new working methods for the human-centered, iterative process of designing such a toolkit. The first stage of toolkit prototypes consists of sketch models with a physical and digital component; focus groups were used to gain in-depth qualitative data. The second stage of toolkit prototypes consists of cardboard prototypes that allow for interaction mimicking the final design experience. It was used to gather data on design interests of different gender and age groups. The third stage of toolkit prototypes, consisting of computing devices with a simple interface, allowed for conducting experimental workshops to quantitatively investigate participants’ self-efficacy and design and engineering interest both before and after the intervention.

A fundamental change in many girls’ mindset was observed in multiple experiments. Findings about requirements for design activities with similar goals are summarized and supported though responses of female middle-school students, who participated in the presented studies.
Simulation of Planetary Gears With Pitting Under Dynamic Conditions
Authors: Inalpolat Murat
Published: November 2017

A computational model of a planetary gearset is developed to investigate the influence of gear tooth pitting on the dynamic response from transmissions that consist of planetary gearsets. The computational model is capable of simulating the system response due to pitting damage under static, quasi-static, and dynamic conditions. Both off-resonant and resonant dynamic conditions have been exploited to understand the influence of resonant dynamics on the transmission vibroacoustic response. Observations on the likelihood of damage detectability under dynamic conditions have been made.
Evaluation of the optic nerve and scleral-choroidal-retinal layer with ultrasound elastography in glaucoma and physiological optic nerve head cupping
Authors: Özen Özkan , Özer Murat Atabey , Tosun Alptekin , Özen Serkan
Published: November 2017

Aim: To evaluate the strain ratio of the optic nerve and retina-choroid-sclera (RCS) layers in individuals with physiological optic disc cupping (PC) and glaucoma patients using strain elastography.Material and methods: We evaluated 56 eyes of 56 subjects (20 eyes with glaucoma, 19 eyes with PC, and 17 normal eyes). The strain ratio of orbital fat to optic nerve (SROFON) was calculated as the ratio of the optic nerve to intraconal fat tissue and the strain ratio of orbital fat to retina-choroid-sclera (SROFRCS) was calculated as the ratio of RCS layers to intraconal fat tissue.Results: SROFON was 0.92 in the control group, 1.07 in the PC group and 1.6 in the glaucoma group and a statistically significant difference was present between the three groups (p<0.05). SROFRCS had no statistically significant difference between the three groups.Conclusions: SROFON values could contribute to the differentiation of the patients with glaucoma and PC.
Motion effects on the measurement of stiffness on ultrasound shear wave elastography: a moving liver fibrosis phantom study
Authors: Shin Hyun Joo , Kim Myung-Joon , Yoon Choon-Sik , Lee Kwanseop , Lee Kwan Sik , Park Jong-Chul , Lee Mi-Jung , Yoon Haesung
Published: November 2017

Aims: To evaluate the differences between shear wave velocities (SWVs) measured with ultrasound elastography during the continuous motion using liver fibrosis phantoms.Materials and methods: Elasticities were measured with convex and linear transducers of supersonic shear wave imaging (SSI) and acoustic radiation force impulse imaging (ARFI) using liver elasticity phantoms (3.0 and 16.9 kPa) at depths of 2, 3, 4, and 5 cm. Motion velocities were 30 and 60 rpm with the phantoms in an upright position on the Orbital shaker. To simulate different directional motion, the phantoms were laid on their side on the shaker. The values between moving and static status were compared, and the number of measurement failure was counted. Results: In SSI, the convex transducer was less affected by motion at 30 rpm with the 3 kPa phantom. In the higher velocity motion and in the higher stiffness phantom, most values from SSI were different comparing with static status, and there was a tendency for elasticity values to increase during movement. In ARFI, there were frequent measurement failures without stable results during the motion.Conclusions: Motion affected the measurement of elasticity differently in SSI and ARFI, according to the velocity, direction of the motion, and phantom stiffness. The convex transducer of SSI was less affected by motion in lower velocity motion and when using normal liver stiffness phantom.
Detection and characterization of small superficially located focal liver lesions by contrast-enhanced ultrasound with high frequency transducers
Authors: Wang Wen-Ping , Dong Yi , Cao Jiaying , Mao Feng , Xu Yadan , Si Qin , Dietrich Christoph F.
Published: November 2017

Aim: To evaluate the benefits of contrast-enhanced ultrasound (CEUS) with high frequency transducers in the detection and characterization of small superficially located focal liver lesions (FLLs).Material and methods: From January 2015 to October 2016, 27 superficial FLLs detected by MRI were examined, first with the low frequency convex transducer (1-5 MHz) and afterwards with a high frequency transducer (7.5-12 MHz). High frequency dynamic CEUS was performed after a bolus injection of 2.4 ml SonoVue®. FLLs were confirmed by histopathology after surgery (n=18) or ultrasound guided 18-gauge core-needle biopsy (n=8), or by MRI follow-up (n =1).Results: The mean diameter of FLLs was 10.5±3.1 mm, and meandepth was 6.2±5.3 mm. While using a high frequency transducerthe detection rate of FLLs (100%, 27/27) was significantly higher than low frequency transducer (25.9%, 7/27) (p<0.05). The overall sensitivity, specificity and diagnostic accuracy were significantly improved by CEUS with a high frequency transducer (sensitivity 88.9%; specificity 92.6%; accuracy 96.2%).Conclusion: Combining CEUS with the performance of high-frequency transducers is a promising technique to improve the detection and accurate diagnosis of small and superficial FLLs appearing indistinctive on BMUS.