bluuebunny/crossref_metadata_2025 huggingface dataset:
Motivational Differences Between Senior and Freshman Engineering Design Students: A Multi-Institution Study
Authors: Bessette Amanda , Morkos Beshoy , Sangelkar Shraddha
Published: December 2016

This research paper presents the initial results of a multi-institute study comparing motivational factors between freshmen and senior mechanical engineering design students. A total of 418 freshman and senior undergraduate mechanical engineering students enrolled at the Florida Institute of Technology and the Pennsylvania State University Erie are studied. To measure motivation we utilize an adaptation of the Motivated Strategies for Learning Questionnaire (MSLQ). The MSLQ examines five factors when measuring motivation and performance. The motivational factors are test anxiety, self-efficacy, and intrinsic value while the performance factors are cognitive value, and self-regulation. Surveys are administered during both the beginning (first two weeks) and end (final two weeks) of the semester. Data is collected from freshmen and seniors through their introduction to engineering and senior design courses, respectively, at both institutes. Statistical analysis compares Likert scale student responses to demographic data. The analysis compares the motivational factors for female versus male, international versus domestic, and senior versus freshman students. Results indicate there is a change in motivational factors as students’ progress from freshman to seniors. Most of the changes are positive, such as a decrease in anxiety, increase in self-recognition, and increase in intrinsic value. Moreover, there were differences between Florida Tech and Penn State students as the makeup of both student bodies are different. This paper will compare the results and provide recommendations for improving motivational factors in freshman students to support their engineering studies and persistence in engineering.
Dynamic Characterization of Vertically Aligned Carbon Nanotube Pads for Materials Handling Applications
Authors: Candelino Nicholas , Jalili Nader
Published: December 2016

Vertically-aligned carbon nanotube (VACNT) pads have recently received widespread attention for use as contact surfaces in material handling processes that involve the transfer of bare silicon wafers. Such processes will benefit from the strong friction force interactions and minimal adhesion force offered by these pads, allowing the wafer to be picked up, carried, and quickly placed, without encountering problems which may arise due to excessive adhesive forces. Despite these benefits, practical implementation has been hindered because VACNTs have nonlinear mechanical characteristics which are still not well understood. Consequently, significant attention has been devoted to fully understand and determine the behaviors associated with their nonlinear dynamic mechanical properties. Along this line, several experimental techniques are applied in this paper to further develop a comprehensive understanding of the mechanical behavior of these pads under compressive loading. It is important to note that the samples used in this testing are not standard VACNTs, but have been grown separately from the final substrate on which they are mounted during testing. After growth, the samples are turned upside-down and fixed so that the bottom ends of all VACNTs are planar and present an ultra-flat top surface for contact during manipulation. The tests performed in this research include a low energy impact test and position controlled load-displacement testing with both constant and sinusoidal velocity loading and unloading. Through these testing procedures, the dependencies of the VACNT material properties to compression depth and displacement rate are observed and an attempt is made to incorporate them into a continuous model. For this, the results from the low energy impact testing provide grounds to state the nature of the nonlinear behavior in our VACNTs. By interrogating the available data from each testing technique, a combination of information provided by the theoretical energy balance and the identified coefficients from the Levenberg-Marquardt curve-fitting algorithm is then applied to generate a parametrized phenomenological model of the VACNT pad behavior. The proposed identified model is continuous and reasonably accounts for the overall material behavior as seen in the experimental data. The validity of this model is shown by means of normalized vector correlation of over 99% between the results of the numerical simulations and the existing experimental data. The material behaviors observed in this research qualitatively support those of several earlier investigators who have previously recognized the complex dissipative behavior of VACNTs. The proposed work itself paves the road for developing a useful engineering model of VACNT pad dynamics which will enable their introduction to mechanical applications in industry.
Numerical Investigations of Parametrically Excited Non-Linear Multi Degree of Freedom Micro-Electromechanical Systems
Authors: Kniffka Till J. , Ecker Horst , Mace Brian R. , Halkyard Roger
Published: December 2016

More and more systems exploit parametric excitation (PE) to improve their performance compared to conventional system. Especially in the field of micro-electromechanical systems (MEMS) such technologies rapidly gain in importance. Different to conventional resonance cases PE may destabilise the system’s rest position when parametrically excited time-periodically with a certain PE frequency. At such parametric resonances vibrations are only limited due to non-linearities. The system is repelled by the unstable rest position and enters a bifurcated limit cycle.

Finding these limit cycles has become more easy in recent years. Advances have been made in numerical path following tools regarding both their power and their user friendliness. As a result, designing such systems has become more common. Indeed, the focus of studies has been on 1DOF systems mostly.

However, for multi degree of freedom systems choosing a meaningful phase space to discuss the results is a task on its own. Quasi-modally transforming the equations of motion, the vibrations are decomposed allowing one to focus on the predominant modes. By concentrating on these predominant modes, continuation results can be displayed in meaningfully reduced phase-parameter spaces. Basins of attraction can be found in Poincaré sections of these phase-parameter spaces.

Employing these approaches, it is demonstrated how to investigate a non-linear 2DOF PE MEMS, how to change the characteristics of the limit cycles and how this affects their basins of attraction.
In-Hand Manipulation Primitives for a Minimal, Underactuated Gripper With Active Surfaces
Authors: Ma Raymond R. , Dollar Aaron M.
Published: December 2016

Dexterous in-hand manipulation tasks have been difficult to execute, even with highly complex hands and control schemes, as the object grasp stability needs to be maintained while it is displaced in the hand workspace. Researchers have shown that underactuated, adaptive hand designs can effectively immobilize objects with simple, open-loop, but there have been few cases where underactuation has been leveraged to enhance in-hand manipulation. In this work, we investigate the performance of a gripper utilizing a thumb with an active, belt-driven, conveyor surface and an opposing, underactuated finger with passive rollers, for a variety of manipulation tasks and range of objects. We show that consistent, repeatable object motion can be obtained while ensuring a rigid grasp without a priori knowledge of the object geometry or contact locations, due to the adaptive qualities of underactuated design. Many dexterous in-hand manipulation examples with their anthropomorphic equivalents are examined, and simple, open-loop control schemes to optimize the repeatability of these tasks are proposed.
Adaptive Semi-Implicit Integrator for Articulated Rigid-Body Systems
Authors: Hewlett Joe , Kovacs Laszlo , Callejo Alfonso , Kry Paul G. , Kövecses József , Angeles Jorge
Published: December 2016

This paper concerns the dynamic simulation of constrained rigid-body systems in the context of real-time applications and stable integrators. The goal is to adaptively find a balance between the stability of an over-damped implicit scheme and the energetic consistency of the symplectic, semi-implicit Euler scheme. As a starting point, we investigate in detail the properties of a new time stepping scheme proposed by Tournier et al., “Stable constrained dynamics”, ACM transactions on Graphics, 2015, which approximates a full non-linear implicit solution with a single linear system without compromising stability. This introduces a geometric stiffness term that improves numerical stability up to a certain time step size, at the cost of large mechanical dissipation compared to the traditional formulation. Dissipation is sometimes undesirable from a mechanical point of view, especially if the dissipation is not quantified. In this paper, we propose to use an additional control parameter to regulate how “implicit” the Jacobian matrix is, and change the degree to which the geometric stiffness term contributes. For the selection of this parameter, adaptive schemes will be proposed based on the monitoring of energy drift. The proposed adaptive method is verified through the simulation of chain-like systems.
Digital Solutions for Integrated and Collaborative Additive Manufacturing
Authors: Lu Yan , Witherell Paul , Lopez Felipe , Assouroko Ibrahim
Published: December 2016

Software tools, knowledge of materials and processes, and data provide three pillars on which Additive Manufacturing (AM) lifecycles and value chains can be supported. These pillars leverage efforts dedicated to the development of AM databases, high-fidelity models, and design and planning support tools. However, as of today, it remains a challenge to integrate distributed AM data and heterogeneous predictive models in software tools to drive a more collaborative AM development environment. In this paper, we describe the development of an analytical framework for integrated and collaborative AM development. Information correlating material, product design, process planning and manufacturing operations are captured and managed in the analytical framework. A layered structure is adopted to support the composability of data, models and knowledge bases. The key technologies to enable composability are discussed along with a suite of tools that assist designers in the management of data, models and knowledge components. A proof-of-concept case study demonstrates the potential of the AM analytical framework.
Semi-Active Suspension Suboptimal Control Using Dynamic Programming of a Quarter Car Suspension System
Authors: Dye John , BuchMueller Nathan , Lankarani Hamid
Published: December 2016

Many modern vehicle control systems utilize automatic braking and torque control to enhance driver inputs for improved stability and deceleration performance of passenger cars. A semi-active suspension approach may allow changes to the suspension characteristics under various conditions or driver inputs during vehicle operation. Suspensions are increasingly using semi active components to enhance handling characteristics by electronically adjusting vehicle dynamics. The active style of adjustment includes modifying suspension parameters directly such as electronic damping rates. The type of controller is important to react or adjust dynamically to the nonlinear nature of suspension systems. An optimal controller is introduced in attempt to improve ride comfort or road handling capability by manipulating the damping coefficient for a given trajectory. A suboptimal approach is given by utilizing a type of receding horizon control. The cost function, as used by Savaresi, contains a bias parameter to shift focus between road holding and passenger comfort. A dynamic quarter car suspension model is presented for simulation of nonlinear vehicle dynamics. During simulation at a given time step, various control inputs are simulated for finite steps into the future. The control input that minimizes the cost function is selected and the simulation time is allowed to advance with that input. The model is simulated using parameters for a typical passenger car and a 100 millisecond update rate from the suboptimal controller. A road profile with a bump is simulated and its transients are analyzed. The suboptimal controller is compared to its purely mechanical realization with a fixed damping coefficient. It is shown when manipulating the cost function ride comfort is desired chassis accelerations are minimized and when maximum road holding is desired tire deflection is minimized.
Modelling Changes in the Dynamic Response of a Cantilever Beam During the Machining Process Using the Discrete Element Method
Authors: Andersen Anders H. , Foldager Frederik F. , Ringgaard Kasper , Balling Ole
Published: December 2016

Production of high accuracy components often involves machining processes. If the machining processes are pushed to increase productivity, it can become challenging to comply with strict tolerances and surface finish requirements. Both the finite element method and the discrete element method have been used for off-line deflection compensation and stability analysis. This contribution investigates the capabilities of a simplified discrete element model in the use for offline simulation of the dynamic behavior of a workpiece during machining. A cantilever beam is modelled and the natural frequencies are monitored as material is removed. Results are compared with theoretical frequencies and with finite element analysis. The model shows a good correspondence in the frequency behavior as material is removed compared with finite element results, though the simple discrete element model under-predicts the stiffness of the beam with approximate 5% for the first two modes.
Design and Analysis of a Reconfigurable Walking Robot Based on 6-URS Mechanism
Authors: Li Yanwen , Sun Wenlong
Published: December 2016

This paper presents a new reconfigurable walking robot that can be applied to the unstructured environment and task. The advantages of reconfigurable robot and walking robot are applied to the walking robot. In order to test and verify the superiority of the robot, the model of 6-URS reconfigurable walking robot is established, the degrees of freedom of the robot before reconfiguration and after reconfiguration is computed separately, and the rationality of the driving plan is judged with the aid of screw theory. Then, the calculation formula of zero moment point is deduced and the stability condition of the robot in the process of walking and reconstructing is obtained according to D’Alembert’s principle. The above analysis shows the 6-URS robot can not only satisfy the requirement of walking but also has the ability of reconfigurability. After reconstructed, the robot can perform the tasks by its arms, such as handling and grabbing. The researching result of this paper possesses important significance on the dynamics analysis, control research and gait planning of this walking robot.
Energy Modeling Method Based on FBS Framework for Energy Efficiency Analysis
Authors: Li Lu , Yu Suiran , Peng Qingjin
Published: December 2016

This paper proposes a FBS-based energy modeling method for highly energy-efficient product design. By this modeling method, the structured relations between the product energy demands and design parameters are developed along with the systematic FBS design process. Meanwhile, by introducing quantified energy analysis to the systematic design domain mapping course, the method helps designers understand energy consuming behaviors of the product and identify efficiency-improving breakthrough points in product design. A case study of a mechanical servo press is presented for the demonstration of this method.
The Impact of Abstraction and Fidelity Levels on the Usefulness of Early System Functional Models
Authors: Hunter Sean C. , Jensen David C. , Tumer Irem Y. , Hoyle Christopher
Published: December 2016

For many complex engineered systems, a risk informed approach to design is critical to ensure both robust safety and system reliability. Early identification of failure paths in complex systems can greatly reduce the costs and risks absorbed by a project in future failure mitigation strategies. By exploring the functional effect of potential failures, designers can identify preferred architectures and technologies prior to acquiring specific knowledge of detailed physical system forms and behaviors. Early design-stage failure analysis is enabled by model-based design, with several research methodologies having been developed to support this design stage analysis through the use of computational models. The abstraction necessary for implementation at the design stage, however, leads to challenges in validating the analysis results presented by these models.

This paper describes initial work on the comparison of models at varying levels of abstraction with results obtained on an experimental testbed in an effort to validate a function-based failure analysis method. Specifically, the potential functional losses of a simple rover vehicle are compared with experimental findings of similar failure scenarios. Expected results of the validation procedure suggest that a model’s validity and quality are a function of the depth to which functional details are described.
Design and Implementation of Cyber-Physical Manufacturing Cloud Using MTConnect
Authors: Liu Xiaoqing Frank , Shahriar Md Rakib , Sunny S. M. Nahian Al , Leu Ming C. , Cheng Maggie , Hu Liwen
Published: December 2016

Cyber-physical systems are gaining momentum in the domain of manufacturing. Cloud Manufacturing is also revolutionizing the manufacturing world. However, although there exist numerous physical manufacturing machines which are network-ready, very few of them are operated in a networked environment due to lack of scalability of existing cyber-physical systems. Combining the features offered by cloud manufacturing and cyber-physical systems, we develop a service-oriented architecture of scalable cyber-physical manufacturing cloud with MTConnect. A testbed of cyber-physical manufacturing cloud is being developed based on the above scalable architecture. In this system, manufacturing machines and their capabilities virtualized in a cyber-physical cloud. Manufacturing operations are represented as web services so that they are accessible across the Internet. Performance of the testbed of our cyber-physical manufacturing cloud with MTConnect is evaluated and test results show that our system achieves excellent service performance of manufacturing operations across Internet.
Monitoring and Change Point Estimation of Normal (In-Control) and Fatigued (Out-of-Control) State in Workers
Authors: Sedighi Maman Zahra , Baghdadi Amir , Megahed Fadel , Cavuoto Lora
Published: December 2016

This paper presents a fused metric for the assessment of physical workload that can improve fatigue detection using a statistical visualization approach. The goal for considering this combined metric is to concisely reduce the number of variables acquired from multiple sensors. The sensor system gathers data from a heart rate monitor and accelerometers placed at different locations on the body including trunk, wrist, hip and ankle. Two common manufacturing tasks of manual material handling and small parts assembly were tested. Statistical process control was used to monitor the metrics for the workload state of the human body. A cumulative sum (CUSUM) statistical analysis was applied to each of the single metrics and the combined metric of heart rate reserve and acceleration (HRR*ACC). The sensor data were transformed to linear profiles by using the CUSUM plot, which can be monitored by profile monitoring techniques. A significant variation between the lifting replications was observed for the combined metric in comparison to the single metrics, which is an important factor in selecting a fused metric. The results show that the proposed approach can improve the ability to detect different states (i.e., fatigue vs. non-fatigued) in the human body.
A Framework for Fused Experimental/Numerical Plant and Control System Optimization Using Iterative G-Optimal Design of Experiments
Authors: Deodhar Nihar , Vermillion Christopher
Published: December 2016

This paper presents a methodology for optimally fusing experiments and numerical simulations in the design of a combined plant and control system. The proposed methodology uses G-optimal Design of Experiments to balance the need for experimental data with the expense of collecting a multitude of experimental results. Specifically, G-optimal design is used to first select a batch of candidate experimental configurations, then determine which of those points to test experimentally and which to numerically simulate. The optimization process is carried out iteratively, where the set of candidate design configurations is shrunken at each iteration using a Z-test, and the numerical model is corrected according to the most recent experimental results. The methodology is presented on a model of an airborne wind energy system, wherein both the center of mass location (plant parameter) and trim pitch angle (controller parameter) are critical to system performance.
Kinematics and Statics Including Cable Sag for Large Cable-Suspended Robots
Authors: Sridhar Dheerendra , Williams Robert L.
Published: December 2016

Cable sag can have significant effects on the cable length computation in a cable-suspended robot and this is more pronounced in large-scale outdoor systems. This requires modeling the cable as a catenary instead of an approximated straight-line model. Furthermore, when there is actuation redundancy involved, the modeling and simulation of the system becomes much more complex, requiring optimizing routines to solve the problem.

A cable-sag-compensated (catenary) model was implemented in simulation for an example large outdoor cable-suspended robot system to solve the coupled kinematics and statics problems. This involved optimization of cable tensions and finding the errors involved in the cable length. A comparative analysis between the straight-line and cable sag model is presented, the main contribution of this paper. Based on the qualitative and quantitative results obtained, recommendations were made on the choice of model and solution methodologies.
Investigating Predictive Metamodeling for Additive Manufacturing
Authors: Yang Zhuo , Eddy Douglas , Krishnamurty Sundar , Grosse Ian , Denno Peter , Lopez Felipe
Published: December 2016

Additive manufacturing (AM) is a new and disruptive technology that comes with a set of unique challenges. One of them is the lack of understanding of the complex relationships between the numerous physical phenomena occurring in these processes. Metamodels can be used to provide a simplified mathematical framework for capturing the behavior of such complex systems. At the same time, they offer a reusable and composable paradigm to study, analyze, diagnose, forecast, and design AM parts and process plans. Training a metamodel requires a large number of experiments and even more so in AM due to the various process parameters involved. To address this challenge, this work analyzes and prescribes metamodeling techniques to select optimal sample points, construct and update metamodels, and test them for specific and isolated physical phenomena. A simplified case study of two different laser welding process experiments is presented to illustrate the potential use of these concepts. We conclude with a discussion on potential future directions, such as data and model integration while also accounting for sources of uncertainty.
Approach Towards a Decision Support System for Additive Manufacturing
Authors: Eddy Douglas , Calderara Justin , Price Mark , Krishnamurty Sundar , Grosse Ian
Published: December 2016

Advancements in the capabilities of additive manufacturing (AM) have increased its usage as an appropriate manufacturing process, particularly when the number of parts in an assembly can be significantly reduced, production volumes are low, or geometric complexity is difficult, if not impossible, to obtain through conventional subtractive processes. However, there are many reasons why it is best to not design a given part based on AM technology. The choice of conventional versus AM manufacturing must occur as early as possible in the design process as this choice can substantially affect how the product is designed. Making the wrong decision will lead to wasted design time, increased time to market the product, a functionally inferior design, and/or a costlier product. To address this critical manufacturing decision, we introduce a usable template and a decision making method for manufacturing process selection which is integrated early into the design process (DS-SAM). This work can serve as the logical foundation for a potential holistic and more mathematically rigorous formulation toward a decision making method that could infer design evaluations based on designer inputs. This approach improves early design efficiency and effectiveness by methodically focusing on the key design process elements to optimally compare alternatives earlier in a design process. The benefits and potential cost savings of using the DS-SAM approach are demonstrated by a pair of case studies, and the results are discussed.
Generic Automated Finger Design
Authors: Honarpardaz Mohammadali , Tarkian Mehdi , Feng Xiaolong , Sirkett Daniel , Ölvander Johan
Published: December 2016

Finger design automation for grippers is one of the areas of highest interest for robot industries. The few studies that have been carried out in the finger design automation research area are limited to objects with specific geometrical properties (e.g. polyhedral). This paper introduces the Generic Automated Finger Design (GAFD) method that contains the essential key processes for automatic design of reliable fingers. The proposed method is implemented on two geometrically complex workpieces and appropriate fingers are designed. The results are discussed in detail and benchmarked against existing approaches.
CGA Approach to Kinematic Analysis of a 2-DoF Parallel Positioning Mechanism
Authors: Li Wanzhen , Sun Tao , Huo Xinming , Song Yimin
Published: December 2016

This paper proposes CGA based approach to determine motions and constraints, analyze mobility, identify singularity of parallel mechanisms, which is perfectly demonstrated by taking 3-RSR&SS parallel positioning mechanism as an example. By introducing CGA, which combining elements of geometry and algebra, the motions and constraints are expressed as simple formulas and their relations are calculated by means of outer product with clear physical meaning, these lead to the motions and constraints are determined in a visual, concise and efficient way, and the number and type of DoF and accessible motions are obtained readily. The inverse and forward position solutions are obtained easily utilizing special geometric relations of 3-RSR&SS parallel positioning mechanism, which are proven by calculating relations among point, line and plane in virtue of CGA operation rules. Two indices of singularity are defined to identify singular configurations of 3-RSR&SS parallel positioning mechanism in the light of the shuffle and outer products. The work of this paper lay a solid theoretical and technical foundation for the prototype design and manufacture of 3-RSR&SS parallel positioning mechanism.
Estimation of the Total Fatigue Life of Metallic Structures
Authors: Abdo Peter , Fardoun Farouk , Huynh Phuoc
Published: December 2016

The fatigue life of a component is defined as the total number of cycles or time to induce fatigue damage and to initiate a dominant fatigue flaw which is propagated to final failure.(Shigley & Mischke 2002)

The aim of this project is to calculate the total fatigue life of metallic structures under cyclic loading by applying equations found by Basquin and Manson-Coffin. The local stresses and strains necessary for the calculation are determined by the finite element method. Former studies concerning this subject have used analytical methods to find the local conditions at the critical section. The analytical methods, based on Neuber and Molski-Glinka’s approaches, permit the calculation of the local stresses and strains at the critical section of the structure’s geometry as a function of the nominal stress (forces) applied.

For the finite elements method, ABAQUS is used to determine the local conditions at the critical section of a T-shaped model.
Multiphase Thermomechanical Topology Optimization of Functionally Graded Lattice Injection Molds
Authors: Wu Tong , Liu Kai , Tovar Andres
Published: December 2016

This work presents a design methodology of lightweight, thermally efficient injection molds with functionally graded lattice structure using multiphase thermomechanical topology optimization. The aim of this methodology is to increase or maintain thermal and mechanical performance as well as to lower the cost of thermomechanical components such as injection molds when these are fabricated using additive manufacturing technologies. The proposed design approach makes use of thermal and mechanical finite element analyses to evaluate the components stiffness and heat conduction in two length scales: mesoscale and macroscale. The mesoscale contains the structural features of the lattice unit cell. Mesoscale homogenized properties are implemented in the macroscale model, which contains the components boundary conditions including the external mechanical loads as well as the heat sources and heat sinks. The macroscale design problem addressed in this work is to find the optimal distribution of given number of lattice unit cell phases within the component so its mass is minimized, while satisfying stiffness and heat conduction constraints of the overall component and the specific regions. This problem is solved through two steps: conceptual design generation and multiphase material distribution. In the first step, the mass is minimized subject to constraints of mechanical compliance and thermal cost function. In the second step, a given number of lattice material are optimally distributed subjected to nonlinear thermal and mechanical constraints, e.g., maximum nodal temperature, maximum nodal displacement. The proposed design approach is demonstrated through 2D and 3D examples including the optimal design of the core of an injection mold. The results demonstrate that a small reduction in mechanical and thermal performance allows for significant mass savings: the second example shows that 3.5% heat conduction reduction and 8.7% stiffness reduction results in 30.3% mass reduction.
Complex Housing: Modelling and Optimization Using an Improved Multi-Objective Simulated Annealing Algorithm
Authors: Cao Pei , Fan Zhaoyan , Gao Robert , Tang Jiong
Published: December 2016

This research concerns the complex housing optimization problem encountered in engineering design, where the volume in space occupied by components need to be minimized along with other objectives and constraints. Since in real applications the constraints are usually complex, the formulation of computationally tractable optimization becomes challenging. In this research, we first develop the mathematical model of such optimization problem, then propose two versions of an improved multi-objective simulated annealing (MOSA) approach towards the design optimization, i.e., optimizing the placement of cylinders under prescribed constraints to minimize the volume occupied, and the estimated plumbing line length. Our case study indicates that the new MOSA algorithm has improved performance towards complex housing with hard constraints and the design can indeed be automated. The outcome of this research may benefit both existing manufacturing practice and future additive manufacturing.
From 5-SS Platform Linkage to Four-Revolute Jointed Planar, Spherical and Bennett Mechanisms
Authors: Ge Xin , Purwar A. , Ge Q. J.
Published: December 2016

Recently, we developed a novel approach to the problem of geometric design of 5-SS platform linkages such that its moving points are constrained on a sphere or a plane. Dual quaternions are used to obtain the bilinear design equations with seven design variables, which can be further recast into a linear equation with 16 design variables with a set of simple proportional relationships. This leads to a novel algorithm that reduces the kinematic design problem to that of null space analysis followed by a generalized eigenvalue problem. In this paper, we show that the same approach leads to a unified algorithm for synthesizing planar, spherical and spatial Bennet mechanisms with four revolute joints as over-constrained four-revolute jointed mechanisms in three dimensional space. Numerical examples are given in the end.
Norigami Folding Machines for Complex 3D Shapes
Authors: Romero J. A. , Diago L. A. , Nara C. , Shinoda J. , Hagiwara I.
Published: December 2016

Creating complex 3D objects from a flat sheet of material using origami folding techniques has attracted attention in science and engineering. Here, we introduce the concept of “Norigami” that is a mixture of three Japanese words: “Nori” that means glue, “Ori” that means Folding, and “Kami”/“Gami” that means paper. Using traditional origami, spherical or other spatial object are very difficult to achieve by a robot due to the complexity of the movements involved. In Norigami complex 3D shapes can be achieved by a machine or robot mixing simple origami folding with pasting patterns. In the current work, a Norigami robot is designed and developed using Lego NXT technology in order to create a spherical object that can be mass produced.
Visualization Study on Two-Phase Flow Behaviors in the Gas-Liquid-Solid Microreactor for Hydrogenation of Nitrobenzene
Authors: Feng Hao , Zhu Xun , Chen Rong , Liao Qiang
Published: December 2016

In this study, visualization study on the gas-liquid two phase flow characteristics in a gas-liquid-solid microchannel reactor was carried out. Palladium nanocatalyst was coated onto the polydopamine functionalized surface of the microchannel through eletroless deposition. The materials characterization results indicated that palladium nanocatalyst were well dispersed on the modified surface. The effects of both the gas and liquid flow rates as well as inlet nitrobenzene concentration on the two-phase flow characteristics were studied. The experimental results revealed that owing to the chemical reaction inside the microreactor, the gas slug length gradually decreased along the flow direction. For a given inlet nitrobenzene concentration, increasing the liquid flow rate or decreasing the gas flow rate would make the variation of the gas slug length more obvious. High inlet nitrobenzene concentration would intensify both the nitrobenzene transfer efficiency and gas reactants consumption, and thereby the flow pattern in the microchannel was transferred from Taylor flow into bubble flow. Besides, the effect of both flow rate and original nitrobenzene concentration on the variation of nitrobenzene conversion and the desired product aniline yield were also discussed.
The Same Initial Condition of the Optimum Method for All Specifications
Authors: Tsugawa Takuji
Published: December 2016

In the previous study (AJK2015-09034 A meridian profile obtained by no restriction in optimum process), an optimum meridian profile of impeller and guidevane by no restriction was obtained. In case of no restriction, all the design parameters and specifications are variable optimum parameters. As the result, the combination of the best design parameters and specifications were selected. In optimum process, blade number, outlet impeller mid span diameter, rotational speed of impeller and specific speed were also variable optimum parameters. As the variable design parameters need to change gradually, the blade number considering as solidity is used as real number in optimum process. There are two kinds of object functions in previous case study. One object function is composed of efficiency and initiated suction specific speed. The ideal goal of efficiency is 100%. The goal of initiated suction specific speed is 1000. The best specific speed of best efficiency was 680 and 852. The other object function is composed of only efficiency. The best specific speed of best efficiency was 520 and 539. The unit of specific speed is composed of m, min−1 and m3/min. In this case study, the initial conditions of design parameters for all design specifications are born from the best one combination of optimum design parameters obtained by no restriction in the previous case study. In this method, the optimum profile for various specifications are obtained by the optimum profile of the best specific speed in condition of changing the specific speed little by little. In previous study, the suitable initial value of all design parameters for each design specifications was not able to obtain. In this case study, the two optimum meridian profiles of low and high specific speed (200 and 3000) was born from one same meridian profile obtained by no restriction in previous optimum process, that is, it become clear that all design parameters calculated by no restriction produces initial value of all design parameters for all specifications in case study of the two kind of specific speed 200 and 3000.

If the ideal goal value of efficiency is 100% and the goal value of the initiated suction specific speed is 1000, the initiated suction specific speed looks like as restriction. If the ideal goal value of the initiated suction specific speed is very large value and the efficiency is not 100% but small value, the efficiency looks like as restriction. The object function contains the efficiency and suction specific speed. The coupling constant combined efficiency and suction specific speed is important constant for the object function. As the result of this case study, one of a meridian profile obtained by no restriction in optimum process was able to become the same initial condition of the optimum method for all specifications.
Laminar-Turbulent Transition Flows of Non-Newtonian Slurries: Models Assessment
Authors: Adane Kofi Freeman K. , Agelin-Chaab Martin
Published: December 2016

In this study a qualitative assessment of transitional velocity engineering models for predicting non-Newtonian slurry flows in a horizontal pipe was performed using data from wide pipe diameters (25–268 mm). In addition, Gamma Theta transition model was used to compute selected flow conditions. In general, it was observed that most of the current engineering models predict conservative transitional velocities. However, caution should be exercised in design situations where both pipe diameter and viscoplastic viscosity influence the value of Hedström number. It was found that the Gamma Theta transition model predicted a laminar flow condition in the fully developed region which is contrary to what has been observed in experiment.
Numerical Study of the Flow Structure and Transport in a Two-Dimensional Channel With Oscillating Periodic Cavities and a Bounding Top Wall
Authors: Ragunathan Srivathsan
Published: December 2016

The dynamics of the flow in a two-dimensional channel with an arrangement of periodic cavities in an oscillating lower bounding wall and a confining top wall is studied numerically in this paper. The open-source CFD code, OpenFOAM v.2.2.2, based on the Finite Volume method is used to solve the problem. The flow dynamics is studied with respect to variations in the location of the confining top wall (non-dimensionalized with the Stokes layer thickness z/δ), cavity-size-based Reynolds Number (Red) and the ratio of the Stokes Layer Thickness to the Cavity Size (δ/d). This is an extension of work done for a previous paper [20]. The evolution and transport of vortex structures in the vicinity of the are presented over the oscillation cycle time by means of instantaneous streamline plots. The effect of the location of the confining top wall on the flow structure is presented in some detail by comparison of the evolution of the streamlines to a case where the top wall is absent. The transfer of fluid mass in and out of the cavity is shown to be strongly dependent on the Red and the z/δ (for the same Red, smaller the z/δ, lower is the mass transfer efficiency).
Investigation of Mean and Turbulent Flow Behaviour Over an Escarpment
Authors: Kilpatrick R. , Siddiqui K. , Hangan H. , Parvu D.
Published: December 2016

Mean and turbulent flow behaviour over a 1:25 scale model of Bolund hill was investigated at Western University’s Wind Engineering, Energy, and Environment Research Institute (WindEEE) using Particle Image Velocimetry (PIV). A range of upstream flow and surface conditions were considered.

Results showed almost no Reynolds dependency on the mean flow and weak dependency of Reynolds number on the upstream surface roughness conditions. However, a strong Reynolds number and upstream surface rough dependency is observed on the turbulent flow particularly in the shear layer formed in the immediate downstream region of the escarpment. It is concluded that the consideration of Reynolds number independency must be cautiously used when extrapolating the flow parameters from scaled model testing to full scale in the field.
Design and Performance Assessments of a Partial Admission Axial Turbine Using Supercritical Carbon Dioxide
Authors: Kang Young-Seok , Huh Jae-Sung , Cho Junhyun , Shin Hyungki , Baik Young-Jin
Published: December 2016

Power density of a super-critical carbon dioxide cycle is very high due to its fluid-like density. For this reason, generally size of turbines are very compact compared to that of the air Brayton cycle. However, such an advantage sometimes becomes a challenge for aerodynamic design, because low volume flow rate of the turbine requires design point at a very low specific speed. One of the solution for the challenge is to design a turbine stage as a partial admission stage in which flow enters the turbine nozzle over only a portion of its annulus. Then it secures a sufficient turbine inlet area, even though performance degradation should be taken in to account.

In this study, aerodynamic design of an axial turbine has been carried out and its performance has been assessed with numerical simulations. One of design requirements for the axial turbine was to minimize rotor inlet and outlet pressure difference to avoid potential axial thrust. In spite of a small amount of expansion ratio in the turbine stage, the absolute pressure difference could cause severe damage to rotor dynamic system and require complicated bearing system. For this reason, in this study, the turbine was designed as impulse type axial turbine with partial admission.

Required rotating speed and resultant low volume flow rate restricted mean diameter and blade height at the stage inlet. The final design has a very low aspect ratio, less than unity. The number of nozzle and rotor are 12 and 34, respectively. The rotating speed of the rotor is 45,000 rpm. The ratio of nozzle arc to blade pitch is approximately 3, which determines efficiency deterioration due to the partial admission.

During the numerical simulations, to implement real gas property, Redlich-Kwong-Aungier cubic equation was used. As the turbine operating point is far from its critical point, the Redlich-Kwong-Aungier cubic equation showed a good agreement with real supercritical gas property.

To assess full and partial admission turbine performance, steady state numerical simulations have been performed. The full annulus CFD domain was constructed for the partial admission stage. At the design condition, there was 15% isentropic efficiency drop in case of the partial admission stage relative to the full admission stage. Also similar amount of power output penalty was investigated from the partial admission case. As the nozzle was choked at the design condition, the mass flow rate was conserved regardless of the admission type. Then in the flowing region, design velocity triangle in front of the rotor well established, while additional loss was generated along the circumferential direction over non flowing region.
An Analytical Study on the Effect of Active Wing Folding and Twist on the Aerodynamic Performance and Energy Consumption of a Bio-Inspired Ornithopter
Authors: Matta Alexander , Bayandor Javid
Published: December 2016

The vast majority of bird scale ornithopters still utilize single active degree of freedom wings in which the flapping motion is actuated at the root of the wing. Yet, as we look to nature, we see that birds utilize more than one active degree of freedom. The purpose of this study is to determine the effect of dynamic wing twist and wing folding on lift and thrust produced by a flapping wing as well as their effects on power consumption. The method of analysis this study utilizes is a version of MST, a Modified Strip Theory, in order to model the aerodynamics of the wing. Both non-folding and folding wing scenarios are considered where the parameters varied include dynamic wing twist amplitude, time averaged wing twist, and dynamic wing twist and flapping phase offset. Furthermore, unlike many other theoretical studies, when examining power consumption both the aerodynamic force as well as inertial effects are considered as inertial effects can be of the same order as aerodynamic force. Moreover, the negative power occurring on the upstroke cannot be always considered to lead to energy transfer back into the system as many studies assume. Thus, this study discusse the impact of negative power and its implications on ornithopter design.
Numerical Simulation of the Flow Field of a Confined, Submerged Slot Jet Impinging on an Oscillating Surface: A Parametric Study
Authors: Ragunathan Srivathsan
Published: December 2016

Impinging jets are an attractive option for spot-cooling of high heat flux devices because of the stagnation region surrounding the point of impingement and the resulting high heat transfer. In small devices with a small jet (microjet) , however, the cooled region due to just a single jet is small. One way to potentially increase this area exposed to the impinging jet is by oscillating the heated surface. In the current paper, the flow structure and transport in a confined and submerged jet impingement arrangement impinging on a wall oscillating horizontally is numerically studied with respect to both parameters governing jet impingement :Jet Reynolds Number (from 40 to 200), distance from the jet inlet to the impinging wall (z/d ratios of 2 and 5) and an oscillation parameter (oscillatory peak Reynolds Numbers of 55 and 110). OpenFOAM v 2.2.2, an open-source CFD code based on the finite volume method is used to solve the problem. The Grid Convergence Index (GCI) is used to estimate discretization uncertainty and error bars on all of the parameters calculated. The flow structure in a confined submerged jet is made up of a double recirculation zone (mostly attributed to the confining top wall) the reattachment regions are associated with a secondary peak in the Nusselt Number. Heat transfer is not studied in this paper. The effect of the oscillating lower wall on the locations of the primary and the secondary recirculation zones are studied with respect to all the parameters mentioned above over a complete oscillation cycle. The local skin friction coefficients along different sections on the lower wall are computed along sections of the oscillating wall and compared to the case where there is no oscillation.The results are anticipated to have significant impact on the heat transfer enhancement possible in such an arrangement.