bluuebunny/crossref_metadata_2025_split huggingface dataset:
Global Sensitivity Analysis for a Bayesian Network
Authors: Li Chenzhao , Mahadevan Sankaran 
Published: December 2016

In a Bayesian network, how a node of interest is affected by the observation of another node is of interest in both forward propagation and backward inference. The proposed global sensitivity analysis (GSA) for Bayesian network aims to calculate the Sobol’ sensitivity index of a node with respect to the node of interest. The desired GSA for Bayesian network confronts two challenges. First, the computation of the Sobol’ index requires a deterministic function while the Bayesian network is a stochastic model. Second, the computation of the Sobol’ index can be expensive, especially if the model inputs are correlated, which is common in a Bayesian network.
To solve the first challenge, this paper uses the auxiliary variable method to convert the path between two nodes in the Bayesian network to a deterministic function, thus making the Sobol’ index computation feasible in a Bayesian network. To solve the second challenge, this paper proposes an efficient algorithm to directly estimate the first-order Sobol’ index from Monte Carlo samples of the prior distribution of the Bayesian network, so that the proposed GSA for Bayesian network is computationally affordable. Before the updating, the proposed algorithm can predict the uncertainty reduction of the node of interest purely using the prior distribution samples, thus providing quantitative guidance for effective observation and updating.
Design Concept Structures in Massive Group Ideation
Authors: Lim Shi Ying Candice , Camburn Bradley Adam , Moreno Diana , Huang Zack , Wood Kristin 
Published: December 2016

Empirical work in design science has highlighted that the process of ideation can significantly affect design outcome. Exploring the design space with both breadth and depth increases the likelihood of achieving better design outcomes. Furthermore, iteratively attempting to solve challenging design problems in large groups over a short time period may be more effective than protracted exploration by an isolated set of individuals. There remains a substantial opportunity to explore the structure of various design concept sets. In addition, many empirical studies cap analysis at sample sizes of less than one hundred individuals. This has provided substantial, though partial, models of the ideation space. This work explores one new territory in large scale ideation. Two conditions are evaluated. In the first condition, an ideation session was run with 2400 practicing designers and engineers from one organization. In the second condition 1000 individuals ideate on the same problem in a completely distributed environment and without awareness of each other. We compare properties of solution sets produced by each of these groups and activities. Analytical tools from network modeling theory are applied as well as traditional ideation metrics such as concept binning with saturation analysis. Structural network modeling is applied to evaluate the interconnectivity of design concepts. This is a strictly quantitative, and at the same time graphically expressive, means to evaluate the diversity of a design solution set. Observations indicate that the group condition approached saturation of distinct categories more rapidly than the individual, distributed condition. The total number of solution categories developed in the group condition was also higher. Additionally, individuals generally provided concepts across a greater number of solution categories in the group condition.
The indication for design practice is that groups of just under forty individuals would provide category saturation within group ideation for a system level design, while distributed individuals may provide additional concept differentiation. This evidence can support development of more systematic ideation strategies. Furthermore, we provide an algorithmic approach for quantitative evaluation of variety in design solution sets using networking analysis techniques. These methods can be used in complex or wicked problems, and system development where the design space is vast.
Mathematical Modelling of the Rear Drive Unit of a Lightweight Vehicle for Sensitivity Analysis of Vibration
Authors: Lin Jiewei , Qiu Yi 
Published: December 2016

Lightweight technology is applied in the automobile industry because mass reduction is beneficial in improving fuel efficiency and reducing CO2 emissions. Apart from the car body and the power unit (the two heaviest parts of a vehicle), the driveline also has potential for a reduction in weight. The driveline transfers power to the wheels and plays an important role in the vehicle system. Vibration is induced by the road input and by unbalanced forces transmitted through the driveline to the car body. Mass reduction in the driveline could influence the dynamic behaviour of a vehicle but it is not yet clear how mass reduction affects vibration of the driveline, the vehicle ride and NVH performance — important considerations when designing a lightweight driveline. In the prototype design stage, a mathematical model provides a more flexible and less costly method of optimising the system dynamics.
In this paper, a 14 degree-of-freedom mathematical model is developed to study the dynamics of a rear drive unit (RDU). The system consists of a rear differential gearbox, left and right constant velocity joints and driveshafts, a rear sub-frame, and bushings between the RDU and the sub-frame and between the sub-frame and the car body. Excitations from the rear wheels, rear suspensions, and input shaft were considered. The vertical acceleration at the rear sub-frame was calculated and correlated with a calibrated multi-body dynamic model of the vehicle developed in a parallel study.
Using a fractional factorial design with the vehicle travelling on a smooth road at various speeds, a sensitivity analysis was carried out with the developed mathematical model to identify the contributions of the mass properties of the RDU and the bushing parameters to the vibration at the centre of gravity (COG) of the rear sub-frame.
Results indicate that the effects of design parameters on the rear sub-frame vibration vary according to the vehicle speed. For vibration at the rear sub-frame, the most influential factors are the masses of the rear differential gearbox and the driveshaft, and the stiffness of the front right bushings between the RDU and the sub-frame. The stiffness of the front left bushing between the RDU and the sub-frame also has considerable effect on the subsystem response but only at higher speeds. Reducing the mass of the CV joint is beneficial in decreasing the vertical vibration at the COG of the rear sub-frame, while reductions in masses of the gearbox and the driveshafts tend to slightly increase the vertical vibration at the same location. However, the adverse effect brought by lightweight differential gearbox and driveshafts on vibration is relatively small that may be hardly detected by passengers. The adverse effect (if any) can be compromised by adjusting the stiffness of the front bushings between the gearbox and the sub-frame.
A Review on Human Motion Prediction in Sit to Stand and Lifting Tasks
Authors: Chumacero-Polanco Erik A. , Yang James 
Published: December 2016

Human-like motion prediction and simulation is an important task with many applications in fields such as occupational-biomechanics, ergonomics in industrial engineering, study of biomechanical systems, prevention of musculoskeletal disorders, computer-graphics animation of articulated figures, prosthesis and exoskeletons design as well as design and control of humanoid robots, among others.
In an effort to get biomechanical insight in many human movements, extensive work has been conducted over the last decades on human-motion prediction of tasks as: walking, running, jumping, standing from a chair, reaching and lifting. This literature review is focused on the STS motion and the LLM. STS is defined as the process of rising from a chair to standing up position without losing stability balance, it is the most ubiquitous and torque-demanding daily labor and it is closely related to other capabilities of the human body. LLM is defined as the activity of raising a load, generally a box, from a low to a higher position while stability is maintained, this task produces a high number of incidences of low-back pain and injuries in many industrial and domestic activities.
In order to predict STS and LLM, two methods have been identified: these are the OBMG method and the CBMG method.
Characterization of Self-Folding Origami Structures Using Magneto-Active Elastomers
Authors: Sung Elaine , Erol Anil , Frecker Mary , von Lockette Paris 
Published: December 2016

Magneto-active elastomers (MAEs) are polymers with magnetic particles that are capable of aligning with an external magnetic field; this self-alignment ability is one reason why MAEs can be used as actuators for folding or bending in origami engineering. The focus of this paper is on experimental characterization and finite element modeling of an MAE folding accordion structure. The goal is to understand the relationships among the applied magnetic field, displacement of the structure during actuation, and the resultant reaction force generated. This relationship is important for applications where force generation caused by the actuation of MAE structures is required.
Data show that force increases with increasing magnetic field, and the work done by the structure can also be calculated by integrating the force. Good agreement between the finite element analysis and experimental data is shown. Future methods for improving experimentation and modeling are discussed based on the results.
Physics Based Modelling of a Magneto-Rheological Equipped Hydro-Pneumatic Semi-Active Suspension System
Authors: Heymans Gerhardus S. , Grobler Jacob F. , Els P. Schalk 
Published: December 2016

The Vehicle Dynamics Group (VDG) at the University of Pretoria has developed a semi-active hydro-pneumatic suspension system for an off road vehicle. The suspension system can switch its characteristics between two discrete spring characteristics as well as two discrete damping characteristics all incorporated in a single suspension strut. This original 4-State Semi-active Suspension System (or 4S4), switches between discrete characteristics through the control a set of solenoid valves. Recently, the 4S4 was further developed with the aim of extending its damping characteristics to be continuously variable through the use of Magneto-rheological (MR) technology. The newly developed MR4S4 prototype received a re-designed flow path which channels the MR suspension fluid through two independent magnetic valves (flow orifice enclosed by coils) in parallel. The damping characteristics of each of the valves are controlled independently by the application of electric currents through damper coils. These valves are also able to block flow completely to achieve the discrete spring characteristics through switching flow to the independent accumulators.
However, in order to ensure that this new technology could be effectively applied and controlled a model of the MR4S4 needed to be developed.
This paper describes the development and validation of a physics based model which is able to capture the overall dynamics and properties of the MR4S4 suspension system. Importantly, the aim of the research was to appropriately capture the physical properties of both the gas as well as the MR fluid as it interacts with the suspension displacements and forces. This model would aid further research in the development of control strategies and provide insight through simulation studies on the systems’ influence on vehicle dynamics.
Value Proposition Design for Systems and Services by Adapting Affordance-Based Design
Authors: Ben Hamida Sonia , Jankovic Marija , Curatella Franco , Sasse Simone , Baltay Suzanne , Callot Martine , Huet Alain , Bocquet Jean-Claude 
Published: December 2016

In early design stages, firms need to generate and assess their value propositions. Although both business developers and systems engineers capture customers’ needs to design the value proposition, they suffer from inefficient business and engineering processes interactions. Moreover, they lack methods to elicit the needs in a structured way and to explore the best value propositions.
We propose to extend the affordance-based design for systems and services in order support the elicitation and capture of stakeholders’values; and to identify boundaries of the system design problem to explore the best value propositions. Hence, affordances — which describe what system provides to other systems and stakeholders — help to frame the context. Today, affordance-based design is mainly used for artifact design. We propose to extend this approach to systems and services and complement it with a focus on stakeholders’ activities and external systems’ stages. With regard to the different system design perimeters defined by affordances, value propositions are designed. The proposed method is illustrated on an AIRBUS Defence & Space innovative project.
Modeling and Simulation of Vehicle Behavior for Design and Tuning of Electronic Differential for Formula Student Vehicle
Authors: Patel Maithili , Mahajan Manthan 
Published: December 2016

A racing vehicle requires to be designed for optimum performance, stability and maneuverability considering all situations like straight line acceleration and high speed cornering. The car is driven close to its tractive limits and a control system becomes inevitable to manifest utmost performance of the car.
In this paper, the focus is on design of an electronic differential for a rear wheel driven Formula Student Electric vehicle, with each rear wheel driven by separate motors. The electronic differential (e-diff) is aimed at both straights and corners, which is fulfilled by considering objective parameters, which assist in cornering by improving yaw rate and straights by improving traction. However, in this paper we shall focus on cornering only. The paper looks at various possible control strategies for obtaining desired values of certain parameters and describes in detail implementation of a yaw rate controlled system.
A vehicle model is created on MATLAB/Simulink platform to look at changes in vehicle behavior in response to various control strategies. The model consists of vehicle dynamics and driver models developed by the authors. The coupled model simulates the vehicle performance on any given track and provides the variation of required parameters. Iterations are done and the results are used to tune the controller parameters to optimize performance on tight turns and overall lap times at the endurance event at the Formula Student competition.
An Observational Study on Functional Behavior in Team Design
Authors: Born Werner , Schmidt Linda 
Published: December 2016

Successful group work is a critical facet of engineering design. In addition to simply increasing the manpower available to solve a particular problem, team settings also leverage the variety of thinking offered by each individual. There are any number of functional behaviors that one might offer a team. This paper explores the idea that design journal records can provide key insight into the functional activities taken on by team members. The main questions asked by this study include (1) Can design journals provide consistent information about an individual’s functional behavior? (2) Are individuals likely to shift behaviors over the course of the project’s timeline? (3) Do individuals adapt to compensate for design behavior changes in other team members?
The data in this study was collected from five volunteer teams of five to six undergraduate students each (total N = 29). At the time of their participation in the study, the volunteers were enrolled in the University of Maryland’s mechanical engineering capstone design course, Integrated Product and Process Development. Four of the teams participated in fall 2015 and one team participated in spring 2014. Participants maintained individual journals throughout their semester-long design projects, after receiving a set of guidelines to steer but not restrict journal usage. After the projects were completed, journals were coded using a previously validated coding scheme which associates each journal entry with a design behavior class and activity.
Findings for this pilot study were very encouraging. Design journals proved to be a viable source of information about the functional behaviors of individuals. The majority of the undergraduate participants in this study were found to regularly shift their focuses to different behaviors as their projects progressed. When these shifts occurred, other team members regularly shifted to accommodate the change and maintain overall similar levels of activity in each area of functional behavior for the team as a whole throughout the project’s timeline.
Design, Fabrication, and Modeling of an Electric-Magnetic Self-Folding Sheet
Authors: Bowen Landen , Springsteen Kara , Ahmed Saad , Arrojado Erika , Frecker Mary , Simpson Timothy W. 
Published: December 2016

A concept recently proposed by the authors is that of a multi-field sheet that folds into several distinct shapes based on the applied field, be it magnetic, electric, or thermal. In this paper the design, fabrication, and modeling of a multi-field bifold is presented that utilizes magneto-active elastomer (MAE) to fold along one axis and P(VDF-TrFE-CTFE) terpolymer to fold along the other axis.
In prior work a dynamic model of self-folding origami was developed which simulated the effect of magneto-active materials on origami-inspired designs. This dynamic model is extended to include the effect of electroactive polymers (EAP) by approximating them as combinations of torques. The accuracy of this approximation is validated using experimental data from a terpolymer-actuated design known as the barking dog. After adjusting crease stiffness within the dynamic model, it shows good correlation with experimental data, indicating that the developed EAP approximation is accurate.
With the capabilities of the dynamic model improved by the EAP approximation method and a refined MAE approximation, the multi-field bifold can be accurately modeled. The model is compared to experimental data obtained from the fabricated multi-field bifold, and is found to predict well the fold angles of the sample. This validation is a first step to the simulation, design, and fabrication of more complicated multi-field sheets.
Nonlinear Thermally Buckled Piezoelectric Energy Harvester
Authors: Ansari M. H. , Karami M. Amin 
Published: December 2016

A thermally buckled piezoelectric energy harvester is designed to power biomedical devices inside the body. The energy harvester (EN) uses the vibrations inside the body to generate the electricity needed for powering biomedical sensors and devices. The piezoelectric beam consists of a brass substrate and two piezoelectric patches attached to the top and the bottom of the substrate. The bimorph beam is inside a rigid frame. The bimorph beam is buckled due to the difference in the coefficient of the thermal expansion of the beam and the frame.
Inside the body, most of the energy content come from the low-frequency vibrations (less than 50 Hz). Having high natural frequency is a major problem in Microelectromechanical systems (MEMS) energy harvesters. Considering the small size of the EN, 1 cm3, the natural frequency is expected to be high. In our design, the natural frequency is lowered significantly by using a buckled beam. A mass is also used in the middle of the beam to decrease the natural frequency even more. Since the beam is buckled, the design is bistable and nonlinear which increases the output power.
In this paper, the natural frequencies and mode shapes of the EN are analytically derived. The geometric nonlinearities are included in the electromechanical coupled governing equations. The governing equations are solved and it is shown that the device generates sufficient electricity to power biomedical sensors and devices inside the human body.
The Application of Retrospective Customer Needs Cultural Risk Indicator Method to Soap Dispenser Design for Children in Ethiopia
Authors: Igleski Joseph R. , Van Bossuyt Douglas L. , Reid Tahira 
Published: December 2016

We present here the design and analysis of a cost-effective soap dispenser that prevents bar soap theft in schools in developing countries. The intended region of deployment is within Ethiopia and surrounding areas. Lack of public hygiene is attributed to 1.4 million global deaths annually due to preventable diarrheal diseases. Using soap while washing hands is estimated to decreases death due to diarrheal diseases by half. Theft of soap from public wash stations, such as those found in schools, is believed to contribute to the spread of diarrheal diseases. Currently there exists no adequate cost-effective solutions to protect bar soap from theft although there appears to be a demand and there is a need for such a device.
An undergraduate student mechanical design team in a sophomore design course at Purdue University was tasked with developing a soap dispenser that prevents theft of bar soap. The project prompt was provided by Purdue Global Engineering Programs’ Innovation to International Development (I2D) Lab. Students were instructed to complete the first step (Product Concept) of the Lean Design for the Developing World (LDW) method to develop a Minimum Viable Product (MVP). The team then completed a retrospective analysis of the MVP using the Customer Needs Cultural Risk Indicator (CNCRI) method to determine potential shortcomings that may be identified in the second step (Validated Learning) of the LDW method. Several customer needs and their component and design solutions that need close monitoring during the second step of the LDW method were identified. The highest risk customer needs included: culturally appropriate design, aesthetic appeal, security, and durability.
Based on the experiences of the design team, several important lessons were learned that can both be applied to improving the secure bar soap dispenser product and to the broader field of product design for the developing world. These lessons include: Customers in the developing world may be more concerned with cost than durability, cultural appeal of a device is highly dependent on first -hand experience and can easily be misunderstood or misrepresented, the LDW method is an invaluable tool in identifying customer needs that may be overlooked due to cultural and socio-economic differences. The use of the LDW framework and the CNCRI method in an undergraduate design group was found to be useful, viable, and valuable to both the undergraduate student learning outcomes and the development of a product that can be deployed to its intended market. Further development of an end-to-end tool chain is needed to better integrate product development for the developing world into mainstream engineering curriculum.