bluuebunny/crossref_metadata_2025 huggingface dataset:
COMPARISON OF FLUOROSCOPY AND COMPUTED TOMOGRAPHY FOR TRACHEAL LUMEN DIAMETER MEASUREMENT AND DETERMINATION OF INTRALUMINAL STENT SIZE IN HEALTHY DOGS
Authors: Williams Jackie M. , Krebs Ingar A. , Riedesel Elizabeth A. , Zhao Qianqian
Published: January 2016

Tracheal collapse is a progressive airway disease that can ultimately result in complete airway obstruction. Intraluminal tracheal stents are a minimally invasive and viable treatment for tracheal collapse once the disease becomes refractory to medical management. Intraluminal stent size is chosen based on the maximum measured tracheal diameter during maximum inflation. The purpose of this prospective, cross‐sectional study was to compare tracheal lumen diameter measurements and subsequent selected stent size using both fluoroscopy and CT and to evaluate inter‐ and intraobserver variability of the measurements. Seventeen healthy Beagles were anesthetized and imaged with fluoroscopy and CT with positive pressure ventilation to 20 cm H2O. Fluoroscopic and CT maximum tracheal diameters were measured by three readers. Three individual measurements were made at eight predetermined tracheal sites for dorsoventral (height) and laterolateral (width) dimensions. Tracheal diameters and stent sizes (based on the maximum tracheal diameter + 10%) were analyzed using a linear mixed model. CT tracheal lumen diameters were larger compared to fluoroscopy at all locations (P‐value < 0.0001). When comparing modalities, fluoroscopic and CT stent sizes were statistically different. Greater overall variation in tracheal diameter measurement (height or width) existed for fluoroscopy compared to CT, both within and among observers. The greater tracheal diameter measured with CT and lower measurement variability has clinical significance, as this may be the imaging modality of choice for appropriate stent selection to minimize complications in veterinary patients.
Evaluation of Different Meshing Techniques for the Case of a Stented Artery
Authors: Lotfi Azadeh , Simmons Anne , Barber Tracie
Published: January 2016

The formation and progression of in-stent restenosis (ISR) in bifurcated vessels may vary depending on the technique used for stenting. This study evaluates the effect of a variety of mesh styles on the accuracy and reliability of computational fluid dynamics (CFD) models in predicting these regions, using an idealized stented nonbifurcated model. The wall shear stress (WSS) and the near-stent recirculating vortices are used as determinants. The meshes comprise unstructured tetrahedral and polyhedral elements. The effects of local refinement, as well as higher-order elements such as prismatic inflation layers and internal hexahedral core, have also been examined. The uncertainty associated with individual mesh style was assessed through verification of calculations using the grid convergence index (GCI) method. The results obtained show that the only condition which allows the reliable comparison of uncertainty estimation between different meshing styles is that the monotonic convergence of grid solutions is in the asymptotic range. Comparisons show the superiority of a flow-adaptive polyhedral mesh over the commonly used adaptive and nonadaptive tetrahedral meshes in terms of resolving the near-stent flow features, GCI value, and prediction of WSS. More accurate estimation of hemodynamic factors was obtained using higher-order elements, such as hexahedral or prismatic grids. Incorporating these higher-order elements, however, was shown to introduce some degrees of numerical diffusion at the transitional area between the two meshes, not necessarily translating into high GCI value. Our data also confirmed the key role of local refinement in improving the performance and accuracy of nonadaptive mesh in predicting flow parameters in models of stented artery. The results of this study can provide a guideline for modeling biofluid domain in complex bifurcated arteries stented in regards to various stenting techniques.
A Cost-Driven Design Methodology for Additive Manufactured Variable Platforms in Product Families
Authors: Yao Xiling , Moon Seung Ki , Bi Guijun
Published: January 2016

Additive manufacturing (AM) has evolved from prototyping to functional part fabrication for a wide range of applications. Challenges exist in developing new product design methodologies to utilize AM-enabled design freedoms while limiting costs at the same time. When major design changes are made to a part, undesired high cost increments may be incurred due to significant adjustments of AM process settings. In this research, we introduce the concept of an additive manufactured variable product platform and its associated process setting platform. Design and process setting adjustments based on a reference part are constrained within a bounded feasible space (FS) in order to limit cost increments. In this paper, we develop a cost-driven design methodology for product families implemented with additive manufactured variable platforms. A fuzzy time-driven activity-based costing (FTDABC) approach is introduced to estimate AM production costs based on process settings. Time equations in the FTDABC are computed in a trained adaptive neuro-fuzzy inference system (ANFIS). The process setting adjustment's FS boundary is identified by solving a multi-objective optimization problem. Variable platform design parameter limitations are computed in a Mamdani-type expert system, and then used as constraints in the design optimization to maximize customer perceived utility. Case studies on designing an R/C racing car family illustrate the proposed methodology and demonstrate that the optimized additive manufactured variable platforms can improve product performances at lower costs than conventional consistent platform-based design.
Limit-Cycle Analysis of Planar Rotor/Autobalancer System Influenced by Alford's Force
Authors: Jung DaeYi , DeSmidt H. A.
Published: January 2016

In recent years, there has been much interest in the use of so-called automatic balancing devices (ABDs) in rotating machinery. Essentially, ABDs or “autobalancers” consist of several freely moving eccentric balancing masses mounted on the rotor, which, at certain operating speeds, act to cancel rotor imbalance at steady-state. This “automatic balancing” phenomenon occurs as a result of nonlinear dynamic interactions between the balancer and rotor, wherein the balancer masses naturally synchronize with the rotor with appropriate phase and cancel the imbalance. However, due to inherent nonlinearity of the autobalancer, the potential for other, undesirable, nonsynchronous limit-cycle behavior exists. In such situations, the balancer masses do not reach their desired synchronous balanced steady-state positions resulting in increased rotor vibration. In this paper, an approximate analytical harmonic solution for the limit cycles is obtained for the special case of symmetric support stiffness together with the so-called Alford's force cross-coupling term. The limit-cycle stability is assessed via Floquet analysis with a perturbation. It is found that the stable balanced synchronous conditions coexist with undesirable nonsynchronous limit cycles. For certain combinations of bearing parameters and operating speeds, the nonsynchronous limit-cycle can be made unstable guaranteeing global asymptotic stability of the synchronous balanced condition. Additionally, the analytical bifurcation of the coexistence zone and the pure balanced synchronous condition is derived. Finally, the analysis is validated through numerical time- and frequency-domain simulation. The findings in this paper yield important insights for researchers wishing to utilize ABDs on rotors having journal bearing support.
Performance and Robustness Improvements in Ultrasonic Transportation Against Large-Scale Streaming
Authors: Jia Kun , Yang Ke-ji , Ju Bing-Feng
Published: January 2016

Acoustic streaming generated from the traveling-wave component of a synthesized sound field often has considerable influence on ultrasonic manipulations, in which the behavior of microparticles may be disturbed. In this work, the large-scale streaming pattern in a chamber with three incident plane waves is simulated, illustrating a directional traveling stream pattern and several vortical structures. Based on the numerical results, the trapping capability of an acoustic potential well is quantitatively characterized according to several evaluation criteria: the boundary and elastic constant of the acoustic potential well, the acoustic radiation force offset ratio, and the elastic constant offset ratio. By optimizing these parameters, the constraint of the acoustic potential well can be strengthened to promote the performance and robustness of the ultrasonic transportation. An ultrasonic manipulation device employing three 1.67-MHz lead zirconate titanate (PZT) transducers with rectangular radiation surface is prototyped and performance tested. The experimental results show that the average fluctuations of a microparticle during transportation have been suppressed into a region less than 0.01 times the wavelength. Particle displacement from equilibrium is no longer observed.
Design Innovation Through Transformation
Authors: Dong Andy
Published: January 2016

The act of changing a product by substituting technologies remains a challenging problem for companies with incumbent and dominant designs. This paper describes a new method to quantify the degree of this change based on the graph edit distance of functional models of products. The knowledge structure of a product is represented by its functional model using the ontology of the functional basis. Its knowledge structure is then compared to an equivalent small-world graph, widely regarded as the most efficient structure for information sharing. Finally, the graph edit distance between a product model and its equivalent small-world graph is calculated. This paper demonstrates a general purpose manner to study design innovation through technological transformation.
Harmonic Balance Method for Nonlinear Vibration of Compound Planetary Gear Sets
Authors: Zhu Weilin , Wu Shijing , Wang Xiaosun
Published: January 2016

In this paper, a new nonlinear time-varying dynamic model for compound planetary gear sets, which incorporates the time-varying meshing stiffness, transmission errors and gear backlash, has been presented. The harmonic balance method (HBM), which is an analytical approach widely used for nonlinear oscillators, is employed to investigate the dynamic characteristics of the gear sets. The matrix form iteration algebraic equations has been established and solved by HBM and single rank inverse Broyden method to reveal the effect of transmission error and gear backlash on the frequency response characteristic of the system. Sub-harmonic resonant, super-harmonic resonant and jump phenomenon have been illustrated by several examples.
Temperature and Stress Examinations on Pistons for Damage Prevention and Efficiency Enhancement: Carbon/Carbon Composite Piston vs Conventional Aluminum Pistons
Authors: Kaan Murat , Kelestemur M. Halidun
Published: January 2016

By identifying well-known failures in pistons, uniquely on skirt area where overlapping with cylinder mainly occurs and causing pistons to fail are investigated. Hence, aim of this paper is to compare two different pistons by analyzing their temperature and stress/strain distributions on specific areas, specifically crown and skirt. By considering the unique properties of carbon, mainly the low coefficient of thermal expansion, density and toughness; expectations in carbon/carbon pistons seemed highly promising compared to conventionally used aluminum pistons. Furthermore, necessary analyses are made by a finite element software package, AbaQus. It is observed that the usage of carbon/carbon composite as a material for pistons shows a high thermal durability which is crucial for necessary cooling stage than aluminum due to its low thermal conductivity property. It is also shown that compared to aluminum, carbon/carbon pistons are 30% lighter in weight, more resistible to mechanical loadings such being pressure, inertial loadings, side forces, and thermal effects. Carbon/carbon composite piston’s tolerance to higher Von Mises stresses around 489 MPa and temperatures up to 664 °C shows a clear superiority when compared to aluminum. Carbon/carbon composite pistons are also much more relevant to be used in an engine for weight reduction and increasing clearance tolerance down to 0.01 mm between the piston and cylinder liner which indirectly reduces the mass of components and directly reduces side forces by a longer connecting rod usage allowance.
Tailored Formulations of Geometric Constraints for Algebraic Analysis of Mechanism Kinematics
Authors: Piipponen Samuli , Hyry Eero , Tuomela Jukka , Müller Andreas
Published: January 2016

Algebraic analysis of the kinematics of large and complicated mechanisms is complicated by the fact that the computational complexity grows very quickly as a function of the number of variables. However, for mechanisms which contain only revolute and/or cylindrical joints one can always simplify the original constraint ideal by choosing the right prime component of the ideal of revolute or cylindrical joint. By making these choices one automatically discards components which are irrelevant to the problem and hence the resulting ideal is simpler than the original. In this way one can immediately analyze some systems whose analysis in the original form is not feasible. As an example we illustrate our results using the spherical 4–bar mechanism.
Modeling and Bifurcation Characteristics of Double Stage Planetary Gear Train With Multiple Clearances
Authors: Zhu Rupeng , Sheng Dongping , Lu Fengxia , Li Miaomiao , Bao Heyun
Published: January 2016

This paper proposes a new non-linear transverse-torsional coupled model for double stage planetary gear train, and gear’s geometric eccentricity error, synthetical transmission error, time-varying meshing stiffness, sun-planet and planet-ring gear pair’s backlashes and sun gear’s bearing clearance are taken into account. The differential governing equations of motion are derived and solved by applying variable step-size Runge-Kutta numerical integration method. The system motion state is investigated systematically and qualitatively, and exhibits diverse bifurcation and chaos characteristics under different bifurcation parameters including meshing frequency, sun-planet backlash and planet-ring backlash. Analysis results showed that the increasing damping could suppress the region of chaotic motion and improve the system’s stability significantly; the route of period-doubling to chaotic motion was observed for both first and second stage’s motion state under the bifurcation parameter of meshing frequency; The routes of period doubling and crisis to chaos were identified under the bifurcation parameter of sun-planet backlash; Besides, the increasing damping ratio could split the bifurcation diagram window into different sections and strong coupling effects are generated to second stage’s motion. Several different types of routes to chaos were observed under the bifurcation parameter of planet-ring backlash including period doubling and 3T-periodic channel; Besides, it concluded that planet-ring backlash could generate a strong coupling effect to both stage’s nonlinear behavior.
Design of a Novel Flexible Endoscope-Cardioscope
Authors: Li Zheng , Oo Min Zin , Nalam Varun , Thang Vu Duc , Yu Haoyong , Ren Hongliang , Kofidis Theodoros
Published: January 2016

In this paper, we present a novel flexible endoscope which is well suited to minimally invasive cardiac surgery (MICS). It is named ‘the Cardioscope’. The Cardioscope is composed of a handle, a rigid shaft, a flexible section and the imaging system. The flexible section is composed of an elastic tube, a number of spacing discs, a constraint tube and four tendons. Compared with other flexible endoscopes, the Cardioscope is much more dexterous. The maximum bending angle of the Cardioscope is 190°. Ex-vivo tests show that the cardioscope is well suited to (MICS), it provides much larger scope of vision than rigid endoscopes and provides good manipulation inside the confined environment. In the test, the Cardioscope successfully explores the full heart through a single hole, which shows the design is promising. Despite it was designed for MICS, the Cardioscope can also be applied to other minimally invasive surgeries, such as laparoscopy, neurosurgery, transnasal and transoral surgery.
New Angular Transmission Design Based on a Four-Bar Linkage Mechanism
Authors: Kim Jong-Won , Bak Jeongae , Seo TaeWon , Kim Jongwon
Published: January 2016

This paper presents a new angular transmission device based on a four-bar linkage mechanism. This mechanism consists of a four-bar linkage and an output gear similar to the Geneva drive. When the input link of the four-bar linkage is rotated once, the trajectory of the coupler point is generated. Then, the coupler point drives the motion of the output gear. To rotate the output gear by a specific angle, the design of the four-bar linkage is very important. The mechanism was generated using a new method for four-bar linkage design. Unlike some conventional methods, the new method can consider both the trajectory and the velocity of a coupler point. The new device has two advantages compared to the Geneva drive. Firstly, because the positions of the input and output axes are close to each other, the space efficiency of the new device is higher than that of the Geneva drive. Secondly, the duty factor of the new device is larger than that of the Geneva drive, and the mechanical loads applied to the output gear, such as that from acceleration, are much lower. Kinematic and dynamic simulation analysis was conducted to verify the advantages of the new device.
Development of a Compliant-Mechanism-Based Compact Three-Axis Force Sensor for High-Precision Manufacturing
Authors: Hao Guangbo , Murphy Marc , Luo Xichun
Published: January 2016

This paper develops a light-weight compact three-axis force senor for high-precision manufacturing application. This sensor uses a cubic three-axial translational compliant parallel mechanism to undergo the loading on its end-effector thereby producing voltages through strain gauges on the deformed beams. The cubic compliant parallel mechanism and sensor system are described at first. Force sensing theoretical analysis is then presented followed by the initial experimental testing and analysis. A linear matrix based multi-axis loading decoupling method is also proposed so that the sensed force can maximally reflect the actual applied force in each axis. The work in this paper is expected to lay a foundation for further investigation into the online force sensing in the high-precision machine tool.
Failure Prediction Model and ESR Modeling of Electrolytic Capacitor With Application to Predictive Maintenance
Authors: Malek Hadi , Dadras Sara , Chen YangQuan
Published: January 2016

Being one of the most used passive components in power electronics, electrolytic capacitors have the shortest life span due to their wear-out failure which is mainly caused by vaporization and deterioration of capacitor electrolyte. Knowing these two phenomena increase Equivalent Series Resistance (ESR) of the capacitor, tracking ESR value over the system operating time can be a good indicator for state of health of an electrolytic capacitor. In order to set the maintenance schedule, various ESR monitoring algorithms computing remaining time before failure have been investigated in literature. These real-time algorithms use classical models for ESR and life-time estimation which are not precise enough and leads the maintenance program to be either risky if the prediction is more than the actual life-time or more expensive if it is much less than the actual life span.

This paper presents a generalized equivalent model using fractional order element for electrolytic capacitor to estimate the ESR and impedance of faultless running capacitor. Unlike other existing fractional order models, proposed model considers a fractional order dynamic only in the dielectric losses and the terminal capacitor remains integer order as observed in actual capacitor’s behavior.

Furthermore, a novel failure predictive model using Mittage-Leffler function is proposed to track the ESR increment due to aging of the capacitor and estimate the failure time based on the information which are provided through ESR monitoring system. Using this model increase the life-time prediction accuracy. Hence the predictive maintenance of the system with capacitors nearing their failure time can be set more precisely. These two fractional order models are compared against classical ESR and life-time prediction models to illustrate the enhanced performances of the proposed models.
Fractional Order Model of Broadband Piezoelectric Energy Harvesters
Authors: Li Dan , Cao Junyi , Zhou Shengxi , Chen Yangquan
Published: January 2016

This paper presents a factional model for broadband piezoelectric energy harvesting systems. Piezoelectric materials pay a significant role in harvesting ambient vibration energy. Due to their inherent characteristics and electromechanical interaction effect, piezoelectric energy harvesting exhibits the hysteresis characteristic under sweeping environmental vibration. Fractional order model of piezoelectric energy harvesting could capture the hysteresis characteristics. Simulation and experimental results show that fractional model of piezoelectric energy harvesting is more effective in describing the system dynamic.
Smart Device and Network Based Control of a Compliant Ankle-Foot-Orthosis
Authors: Zhu Yong
Published: January 2016

Ankle Foot Orthoses (AFO) are externally applied devices that control the foot and ankle joint complex. The goal of this project is to create a smart device and network based mobile control, communicator and mechanical performance analyzer for a prototype AFO, which is powered by artificial pneumatic muscles to aid walking in patients with ankle and foot injuries. The preliminary proof of concept study of the system to improve comfort and offer settings control will be presented. It can potentially provide a higher computing and analyzing power in the design of medical devices by the combination of smart mobile device technology with microcontrollers and Internet.
A Total Lagrangian ANCF Liquid Sloshing Approach for Multibody System Applications
Authors: Wei Cheng , Wang Liang , Shabana Ahmed A.
Published: January 2016

The objective of this investigation is to develop a total Lagrangian non-incremental liquid sloshing solution procedure based on the finite element (FE) absolute nodal coordinate formulation (ANCF). The proposed liquid sloshing modeling approach can be used to avoid the difficulties of integrating most of fluid dynamics formulations, which are based on the Eulerian approach, with multibody system (MBS) dynamics formulations, which are based on a total Lagrangian approach. The proposed total Lagrangian FE fluid dynamics formulation, which can be systematically integrated with computational MBS algorithms, differs significantly from the conventional FE or finite volume methods which are based on an Eulerian representation that employs the velocity field of a fixed control volume in the region of interest. The ANCF fluid equations are expressed in terms of displacement and gradient coordinates of material points, allowing for straight forward implementation of kinematic constraint equations and for the systematic modeling of the interaction of the fluid with the external environment or with rigid and flexible bodies. The fluid incompressibility conditions and surface traction forces are considered and derived directly from the Navier Stokes equations. Two ANCF brick elements, one is obtained using an incomplete polynomial representation and the other is obtained from a B-spline volume representation, are used. The new approach ensures the continuity of the displacement gradients at the nodal points and allows for imposing higher degree of continuity across the element interface by applying algebraic constraint equations that can be used to eliminate dependent variables and reduce the model dimensionality. Regardless of the magnitude of the fluid displacement, the fluid has a constant mass matrix, leading to zero Coriolis and centrifugal forces. The analysis presented in this paper demonstrates the feasibility of developing an efficient non-incremental total Lagrangian approach for modeling sloshing problems in MBS system applications in which the bodies can experience large displacements including finite rotations. Several examples are presented in order to shed light on the potential of using the ANCF liquid sloshing formulation developed in this study.
Comparison Principle and Solution Bound of Fractional Differential Equations
Authors: Xu Yufeng
Published: January 2016

The comparison principle of fractional differential equations is discussed in this paper. We obtain two kinds of comparison principle which are related to the functions in the right hand side of equations, and the order of fractional derivative, respectively. By using the comparison principle, the boundedness of fractional Lorenz system and fractional Lorenz-like system are studied numerically. Numerical simulations are carried out which demonstrate our theoretical analysis.
Large Motion Visualization and Estimation for Fluid-Structure Simulations
Authors: Hsu Tzu-Sheng Shane , Fitzgerald Timothy , Nguyen Vincent Phuc , Balachandran Balakumar
Published: January 2016

Studies of fluid-structure interactions associated with flexible structures such as flapping wings require the capture and quantification of large motions of bodies that may be opaque. As a case study, motion capture of a free flying insect is considered by using three synchronized high-speed cameras. A solid finite element (FE) representation is used as a reference body and successive snapshots in time of the displacement fields are reconstructed via an optimization procedure. One of the original aspects of this work is the formulation of an objective function and the use of shadow matching and strain-energy regularization. With this objective function, the authors penalize the shape differences between silhouettes of the captured images and the FE representation of the deformed body. A similar method with a three-dimensional voxel cloud (VC) reconstruction is also illustrated. Challenges faced in implementing the VC method are discussed and the current computational implementation will also be covered.
Research on Efficiency and Load Sharing Characteristics of High-Speed-Ratio Planetary Gear Transmissions
Authors: Liang Jianbin , Qin Datong , Wen Wei , Jiang Jun
Published: January 2016

Wolfrom planetary gear (WPG), James Ferguson planetary gear (JFPG) and plus-planetary gear (PPG), feature high speed ratios and a low number of gears, but their efficiency is low and their performance is sensitive to manufacturing errors. In this paper, low-loss gears are used to improve the efficiency of these high-speed-ratio planetary gear transmissions. The methods to achieve the low-loss gears are optimizing modification coefficients and addendum coefficients simultaneously in order to equalize approach-contact ratio and recess-contact ratio. Besides, the sensitivity of the load sharing performance to manufacturing errors is analyzed in the view of load sharing characteristics. A load sharing model, which includes position errors of planet bearings and tooth profile errors of planets, is built up to obtain the load sharing characteristics of WPG, JFPG and PPG. Load sharing performance of WPG, JFPG and PPG with manufacturing errors are analyzed. And effects of load sharing measures are compared.
Study on Induced Principal Curvature and Induced Principal Direction Based on Normal Vector of Instantaneous Contact Line
Authors: Zhao Yaping , Xi Chenru , Zhang Yimin
Published: January 2016

The computing formulae, in different forms, for the normal vector of the instantaneous contact line are summarized systematically. For some of them, the distinct and sententious proof techniques are put forward. Based on the normal vector of the transient contact line, the computing formulae for the induced normal curvature and the induced geodesic torsion are deduced laconically and strictly. Owing to making use of the normal vector of the transient contact line, the style of the obtained formulae is more elegant. Particularly, a novel developing approach for the computing formula of the induced geodesic torsion is proposed. On the basis of the induced geodesic torsion, the computing formulae for the induced principal directions are derived. From this, the calculating formulae for the induced principal curvatures are obtained rigorously and conveniently. All these work reveal the pivotal position of the normal vector of the momentary contact line in the meshing theory for the line conjugate gearing. By right of the meshing theory established, the meshing analysis for the modified TA worm drive is performed. A number of basic and important formulae are attained and the numerical outcome of the induced principal curvature is given out.
The Value of Flexible Capacity Expansion Strategies in Design of Complex Decentralized Engineering Systems
Authors: Hu Junfei , Cardin Michel-Alexandre
Published: January 2016

This paper presents and applies a simulation-based methodology to assess the value of flexible decentralized engineering systems (i.e., the ability to flexibly expand the capacity in multiple sites over time and space). This work differs from others by analyzing explicitly the tradeoffs between economies of scale (EoS) — which favors building large capacity upfront to reduce unit cost and accommodate high anticipated demand — and the time value of money — which favors deferring capacity investments to the future and deploying smaller modules to reduce unit cost. The study aims to identify the best strategies to deploy capacity of complex engineered systems over time and improve their economic lifecycle performance in the face of uncertainty. This study is illustrated using a waste-to-energy system operated in Singapore. The results show that a decentralized design with the real option to expand the capacity in different locations and times improves the expected net present value by more than 20% under the condition of economies of scale α = 0.8 and discount rate λ = 8%, as compared to a fixed centralized design. The results also indicate that a flexible decentralized design outperforms other rigid designs under certain circumstances since it not only reduces transportation costs, but also has the advantage of flexible deployment strategies, such as deferring investment and avoiding unnecessary capacity. The results help designers and managers better compare centralized and decentralized design opportunities and to recognize the value of flexible decentralized designs in small-scale urban environments. The example also provides guidance for applying flexibility to a wider range of complex engineered systems and to determine the best strategies for deploying the capacity of systems in other urban contexts.
Mathematical Classification of the Spiral and Ring Galaxy Morphologies Based on the Fractional Trigonometry
Authors: Lorenzo Carl F. , Hartley Tom T.
Published: January 2016

The ongoing development of the fractional trigonometry has created a new set of spiral functions, the fractional spiral functions. These spirals include both barred and normal spirals in a common formulation. This paper studies the applicability of the fractional spirals to the mathematical classification of spiral and ring galaxy morphologies. The fractional spirals are found to provide a high quality fit to a variety of ring and spiral galaxies over a significant range of the spiral length. Further, the r–s character of the de Vaucouleurs classification is found to relate to particular parameters of the spirals. Additional benefits include; direct inference of galaxies inclination, estimates of major deviations of the galaxy optical center from the geometric center, and further application of the mathematical description of the galaxy morphology.
Sliding Mode Control of an Exoskeleton Gait Rehabilitation Robot Driven by Pneumatic Muscle Actuators
Authors: Cao Jinghui , Xie Sheng Quan , McDaid Andrew , Das Raj
Published: January 2016

This paper firstly summarizes a newly developed knee joint mechanism of a gait rehabilitation robot, as well as a modified dynamics model for pneumatic muscle actuators (PMAs). The major sections focus on the development of single-input-single-output sliding mode trajectory tracking controller for the knee mechanism. The sliding mode controller takes the models of the whole system, which include the pneumatic flow dynamics of the analogue valves and PMAs, dynamic model of the PMAs and dynamics of the mechanism, into account. It controls the voltage applied to the valves to track desired angular trajectories of the knee joint. The preliminary experiments on the sliding mode controller have been conducted and the results have indicated that the knee mechanism’s successful tracking of sinusoidal waves with frequencies and magnitudes closed to actual human gait. Currently, the researchers are working on the development of multi-inputs-multi-outputs control of the mechanism for both trajectory tracking and compliance adjustments.
Designing Rigidly Foldable Horns Using Bricard’s Octahedron
Authors: Tachi Tomohiro
Published: January 2016

This paper proposes a design method to obtain a family of rigidly foldable structures with one degree of freedom. The mechanism of flat-foldable degree-four cones and mutually compatible cones sharing a boundary are interpreted as the mechanism of Bricard’s flexible octahedra. By sequentially concatenating compatible cones, one can design horn-shaped rigid-origami mechanisms. This paper presents a method to inversely obtain rigidly foldable horns that follow given space curves. The resulting rigidly foldable horns can be used as building blocks for a transformable cellular structure and attachments to existing rigidly foldable structures.
Methods for Selecting Level of Automation: A Critical Comparison of Approaches and Integrated Proposal
Authors: Salmi Anas , Dhulia Jayavardhan , Summers Joshua D. , David Pierre , Blanco Eric
Published: January 2016

The purpose of this paper is to first review and then propose methods for determining the appropriate levels of automation for assembly operations. Based on a literature review in decision making methods, an evaluation against method requirements is made. The analysis shows that no single method fulfills all the defined requirements, yet two methods are identified that jointly address all the requirements: Boothroyd’s and Dewhurst (B&D) method and the Dynamo method. B&D and Dynamo methods are then combined into a new method, exploiting elements of each. An additional step for graphical modeling of the assembly processes using the Assembly Sequence Modeling Language (ASML) is integrated to facilitate alternative exploration. This newly proposed method is discussed and revealed promising in the field of assembly systems Level of Automation (LoA) measurement and improvement.
Realizations for Determining the Energy Stored in Fractional-Order Operators
Authors: Hartley Tom T. , Lorenzo Carl F.
Published: January 2016

The purpose of this paper is to determine physical electrical circuits, in both impedance and admittance forms, that match fractional-order integrators and differentiators, namely 1/sq and sq. Then, using these idealized infinite-dimensional circuits, the energy storage and loss expressions for them are determined, carefully relating the associated infinite-dimensional state variables to physically meaningful quantities. The resulting realizations and energy expressions allow a variety of implementations for understanding the transient behavior of fractional-order systems.
The Way Makers Prototype: Principles of DIY Design
Authors: Camburn Bradley A. , Sng Karen H. , Perez K. Blake , Otto Kevin , Wood Kristin L. , Jensen Daniel , Crawford Richard
Published: January 2016

Recent research demonstrates the importance of prototyping to support early stage design efforts. There remains a substantial opportunity to provide tools that codify the leap between the logical objectives of the design effort, and an individual’s intuitive design and fabrication experience. This study investigates project articles on the open source, Do-It-Yourself (DIY) design repository, Instructables.com. The database contains guides for producing low cost functional prototypes. Many entries in the repository include documentation of the design process along with instructions for fabrication. Through a systematic research methodology, we extract five prototype design and fabrication principles from articles in the database. An online crowdsourced assessment enables inter-rater testing, with multiple parallel raters. This assessment validates presence of the principles in the database. A controlled study was conducted in which one of two groups was exposed to the principles. This study evaluates connectivity, successful adoption of the principles by participants in the experimental group, and resulting design performance effects. Two case studies of prototyping are also provided. Observations indicate that application of the principles positively impacts prototyping outcomes. A potential area for improvement is edge case evaluation, i.e. principles only found in a single extraordinary sample.
Correlation of Relevant Case Properties and the Flank Load Carrying Capacity of Case-Hardened Gears
Authors: Koenig Johannes , Koller Peter , Tobie Thomas , Stahl Karsten
Published: January 2016

The flank load carrying capacity of case-hardened gears is significantly influenced by the condition of the case properties. A negatively influenced case, e.g. due to grinding burn, may result in a significantly reduced load carrying capacity of the tooth flank. On the other hand, additional finishing methods such as shot peening and superfinishing allow a positive influence on the case properties, resulting in a further increase of the tooth flank load carrying capacity. The variation of the case properties is not adequately taken into account by the current standards DIN 3990 / ISO 6336.

This paper summarizes the results of the FVA research project 521 I. This project investigated the effects of shot peening and superfinishing on the tooth flank load carrying capacity. Based on the experimental results, an extension of the calculation method for the permissible contact stress σHP is proposed.
Prediction of Isolated Resonance Curves Using Nonlinear Normal Modes
Authors: Kuether R. J. , Renson L. , Detroux T. , Grappasonni C. , Kerschen G. , Allen M. S.
Published: January 2016

Isolated resonance curves are separate from the main nonlinear forced-response branch, so they can easily be missed by a continuation algorithm and the resonant response might be underpredicted. The present work explores the connection between these isolated resonances and the nonlinear normal modes of the system and adapts an energy balance criterion to connect the two. This approach provides new insights into the occurrence of isolated resonances as well as a method to find an initial guess to compute the isolated resonance curve using numerical continuation.

The concepts are illustrated on a finite element model of a cantilever beam with a nonlinear spring at its tip. This system presents jumps in both frequency and amplitude in its response to a swept sinusoidal excitation. The jumps are found to be the result of a modal interaction that creates an isolated resonance curve that eventually merges with the main resonance branch as the excitation force increases. Excellent insight into the observed dynamics is provided with the NNM theory, which supports that NNMs can also be a useful tool for predicting isolated resonance curves and other behaviors in the damped, forced response.
Accurate Model for the Minimum Volume Design of Single Stage Spur Gear Train
Authors: Wang Cheng , Shi Zhao Yao
Published: January 2016

At present, the existing problems in gear volume optimization include: (1) the clearance volume caused by the bottom clearance and addendum modification is not considered in the volume models which causes the error of volume calculation. (2) Gears employ fixed structure and their structural changes caused by the dimension changes are not considered in the process of optimization. In view of the above mentioned problems, the paper firstly deduces the formula of clearance volume. An example is provided to verify that the clearance volume should be considered in the accurate calculation of gear volume. Secondly, volume formulas of different structure of spur gear including solid structure, web-type structure, spoke type structure with cross shape section and with H-shape section are deduced. The design variables, objective function and constrains are briefly introduced. Finally, a single stage spur gear train is as an example, the optimization is carried out. The result shows when the transmission ratio is changed from 3.2 to 2, the structure of gear changes from the web-type to the solid. It means gear with fixed structure is not reasonable in the process of optimization.
Improved Voltage Sag Detection Method and Optimal Design for the Digital Low-Pass Filter in Small UAVs
Authors: Pei Shuiqiang , Hu Xiaoguang , Zhang Guofeng , Fu Li
Published: January 2016

Real-time and accurate detection of the voltage sag characteristics is the premise to achieve dynamic voltage restorer compensation. An improved αβ-dq transformation detection method is presented for the limitations of traditional detection methods. In this method, the α-axis component of the αβ static coordinate system is deduced according to the single-phase voltage. The virtual β-axis component is constructed from the derivative of the α-axis component. The magnitudes, duration, phase-angle jump of the voltage sag are detected quickly and accurately by αβ-dq transformation and low-pass filter. The original data is real-time, which ensures faster detection response speed and reduces the computation greatly. In addition, an optimization design method for digital low-pass filter is presented against the contradictions existing in real-time and filtering effect of common low-pass filter. This adopts inertial filter to improve the characteristics of Butterworth low-pass filter and enable them to better adapt to the needs of the voltage sag detection thus improving the real-time quality and precision of dynamic voltage restorer.
Modeling and Adaptive Robust Posture Control of 3-RPS Pneumatic Parallel Platform
Authors: Shang Ce , Tao Guoliang , Zuo He , Meng Deyuan
Published: January 2016

Due to the compressibility, nonlinear characteristic and parameters uncertainty, the position control of a pneumatic cylinder or parallel platform is still very difficult while compared with the electro-driven ones. In this paper, the dynamic model of a single proportional value controlled pneumatic cylinder is established. In order to reduce the affection of the parameters uncertainty, the online parameters estimation is adopted into the controller design. Based on the NI CompactRio hardware and Veristand platform, the algorithm is realized to the physical system successfully. The position error is generally lower than 1%. Then, the algorithm is expanded to the problem for the 3-RPS pneumatic parallel platform. The Lyapunov’s method is used to prove the effectiveness of controller and the experiment results show that the posture error of the platform can be as low as 0.5%. By using this approach, the pneumatic ones can be much more competitive and valuable in the industrial market of position or posture control.
An Innovative Navigation Strategy for Autonomous Underwater Vehicles: An Unscented Kalman Filter Based Approach
Authors: Allotta Benedetto , Costanzi Riccardo , Meli Enrico , Ridolfi Alessandro , Chisci Luigi , Fantacci Claudio , Caiti Andrea , Di Corato Francesco , Fenucci Davide
Published: January 2016

Developing reliable navigation strategies is mandatory in the field of Underwater Robotics and in particular for Autonomous Underwater Vehicles (AUVs) to ensure the correct achievement of a mission. Underwater navigation is still nowadays critical, e.g. due to lack of access to satellite navigation systems (e.g. the Global Positioning System, GPS): an AUV typically proceeds for long time intervals only relying on the measurements of its on-board sensors, without any communication with the outside environment. In this context, the filtering algorithm for the estimation of the AUV state is a key factor for the performance of the system; i.e. the filtering algorithm used to estimate the state of the AUV has to guarantee a satisfactory underwater navigation accuracy. In this paper, the authors present an underwater navigation system which exploits measurements from an Inertial Measurement Unit (IMU), Doppler Velocity Log (DVL) and a Pressure Sensor (PS) for the depth, and relies on either an Extended Kalman Filter (EKF) or an Unscented Kalman Filter (UKF) for state estimation. A comparison between the EKF approach, classically adopted in the field of underwater robotics and the UKF is given. These navigation algorithms have been experimentally validated through the data related to some sea tests with the Typhoon class AUVs, designed and assembled by the Department of Industrial Engineering of the Florence University (DIEF) for exploration and surveillance of underwater archaeological sites in the framework of the THESAURUS and European ARROWS projects. The comparison results are significant as the two filtering strategies are based on the same process and sensors models. At this initial stage of the research activity, the navigation algorithms have been tested offline. The presented results rely on the experimental navigation data acquired during two different sea missions: in the first one, Typhoon AUV #1 navigated in a Remotely Operated Vehicle (ROV) mode near Livorno, Italy, during the final demo of THESAURUS project (held in August 2013); in the latter Typhoon AUV #2 autonomously navigated near La Spezia in the framework of the NATO CommsNet13 experiment, Italy (held in September 2013). The achieved results demonstrate the effectiveness of both navigation algorithms and the superiority of the UKF without increasing the computational load. The algorithms are both affordable for online on-board AUV implementation and new tests at sea are planned for spring 2015.
Measurement of 3D Objects in a Robotic Cell
Authors: Wojciechowski Jakub , Ciszak Olaf
Published: January 2016

There is reduction in implementation costs of systems considered too complicated and expensive caused by increasing efficiency and availability of hardware and software. The paper contains a proposal to extend features of standard vision system by 3D scanning capability. System is expected to be implemented in new and existing robotic stations. Basic mathematical equations and hints for the selection of system components are provided.