bluuebunny/crossref_metadata_2025 huggingface dataset:
Three-Position Synthesis of Spherically Constrained Planar 3R Chains
Authors: Abdul-Sater Kassim , Irlinger Franz , Lueth Tim C.
Published: January 2016

This paper presents a dimensional finite position synthesis procedure for a 8-bar linkage, that we call the spherically constrained planar 3R chain. The procedure aims at using the well-developed constraint-based synthesis equations of spherical RR chains in order to constrain a planar serial 3R guiding chain, synthesized before for a maximum number of three task poses. This maximum number of task positions results from the specific linkage topology, which requires to select specific axes of spherical RR chains. However, three-position synthesis allows it to apply a specific version of the dyad triangle equation of planar RR chains to the problem. A particular assumption forces that this version of the dyad triangle equation becomes nothing but the synthesis equation of a planar 3R chain, which is easily solved for the three prescribed task poses. An example is provided showing a synthesized spherically constrained planar 3R chain reaching three prescribed planar poses.
Feature Improvement and Cost Reduction of Baitcasting Fishing Reels for Emerging Markets
Authors: Hume David , Isava Monica , Koepsell Emily , Kriebel Andrew , Marshall Adam , Slocum Jonathan , Jeunnette Mark , Winter Amos
Published: January 2016

Baitcasting fishing reels are a challenging product to sell to new users in emerging markets. Their complex and less-than-intuitive design make them poor candidates for a novice fisherman selecting his or her first fishing reel. Based upon manufacturer constraints and design requirements, our team lowered the price point and improved the usability of the Okuma Cerros baitcasting fishing reel to make it more appealing to a wider range of consumers, especially in emerging markets. This project resulted in a three-phase redesign: reducing cost via alternative materials and replacing bearings with bushings; prototyping a simplified cast control system; and proposing an improved user interface.
Using Optimization for the Mixed Exact-Approximate Synthesis of Planar Mechanisms
Authors: Sundram Jugesh , Larochelle Pierre
Published: January 2016

Exact synthesis algorithms for planar mechanisms for rigid-body guidance are limited by the number of poses the mechanism can position the rigid-body in Euclidean space. The mixed exact-approximate synthesis algorithm described guides a rigid exactly through two positions and approximately through n guiding positions. It breaks down a rigid-body guidance task into n sub-problems of three positions to be solved by an exact synthesis algorithm. A novel algorithm utilizing MATLAB’s constrained non-linear optimization tools is proposed. The algorithm can be utilized to find within a bounded design parameter space the RR dyad that exactly reaches two positions and minimizes the distance to n positions. Two such dyads can be synthesized independently and then combined to yield a planar four-bar mechanism. An example using the proposed algorithm to design a planar four-bar mechanism to solve McCarthy’s 11-position synthesis problem stated at the 2002 ASME Conference is included.
Multibody Analysis and Design of a Reconfigurable Parallel Kinematics Manipulator
Authors: Palpacelli Matteo , Callegari Massimo , Carbonari Luca , Palmieri Giacomo
Published: January 2016

This paper presents the design of a reconfigurable parallel kinematics machine endowed with three degrees of freedom of pure translation, or alternately of pure rotation. Such reconfigurability results from the use of lockable spherical joints, which realize the connection between each robot leg and the moving platform. Three actuated legs are used to drive the platform motion. The change of configuration occurs only at a specific pose, called home configuration. A control strategy allows to manage the shift phase and activate the two mobilities one at a time. Multibody simulations allowed to analyze the dynamic behavior of the manipulator and to verify the choices made with regard to the robot mechanics and the size of actuation systems. Position and differential kinematics of the manipulator are briefly introduced in order to demonstrate the simplicity of the analytic expressions and the mechanical feasibility of the manipulator.
A Computer Vision Approach for Automatically Mining and Classifying End of Life Products and Components
Authors: Dering Matthew L. , Tucker Conrad S.
Published: January 2016

The authors of this work present a computer vision approach that discovers and classifies objects in a video stream, towards an automated system for managing End of Life (EOL) waste streams. Currently, the sorting stage of EOL waste management is an extremely manual and tedious process that increases the costs of EOL options and minimizes its attractiveness as a profitable enterprise solution. There have been a wide range of EOL methodologies proposed in the engineering design community that focus on determining the optimal EOL strategies of reuse, recycle, remanufacturing and resynthesis. However, many of these methodologies assume a product/component disassembly cost based on human labor, which hereby increases the cost of EOL waste management. For example, recent EOL options such as resynthesis, rely heavily on the optimal sorting and combining of components in a novel way to form new products. This process however, requires considerable manual labor that may make this option less attractive, given products with highly complex interactions and components. To mitigate these challenges, the authors propose a computer vision system that takes live video streams of incoming EOL waste and i) automatically identifies and classifies products/components of interest and ii) predicts the EOL process that will be needed for a given product/component that is classified. A case study involving an EOL waste stream video is used to demonstrate the predictive accuracy of the proposed methodology in identifying and classifying EOL objects.
A Dynamic Model for Double-Planet Planetary Gearsets
Authors: Fyler Dylan C. , Inalpolat Murat
Published: January 2016

In this study, a two-dimensional, steady-state, discrete dynamic model of a double-planet planetary gearset is proposed. The dynamic model is generalized such that it can consist of number of planet branches and can operate under any operating conditions (load and speed). The contact between each external to external and external to internal gear pair is modeled to obtain stiffnesses and mesh displacement excitations using a generalized load distribution model. The natural modes are computed by solving the corresponding eigenvalue problem. The forced vibration response to gear mesh excitations is obtained by applying the modal summation technique. The model is capable of predicting gear mesh dynamic load and dynamic transmission error spectra for each gear mesh, dynamic bearing load spectra for each bearing as well as gear body dynamic displacements. Forced vibration response of an example system that consists of three double-planet branches is studied to demonstrate the influence of some of the key design parameters.
Optimization of a Dynamic Model of Magnetic Actuation of an Origami Mechanism
Authors: Bowen Landen , Springsteen Kara , Frecker Mary , Simpson Timothy
Published: January 2016

Self-folding origami has the potential to be utilized in novel areas such as self-assembling robotics and shape-morphing structures. Important decisions in the development of such applications include the choice of active material and its placement on the origami model. With proper placement, the error between the actual and target shapes can be minimized along with cost, weight, and power requirements. Through the incorporation of dynamic models of self-folding origami mechanisms into an optimization routine, optimal orientations for magnetically-active material are identified that minimize error to specified target shapes. The dynamic models, created using Adams 2014, are refined by improvements to magnetic material simulation and more accurate joint stiffness characterization. Self-folding dynamic models of the waterbomb base and Shafer’s Frog Tongue are optimized, demonstrating the potential use of this process as a design tool for other self-folding origami mechanisms.
The D3 Science-to-Design Methodology: Automated and Cognitive-Based Processes for Discovering, Describing, and Designing Complex Nanomechanical Biosystems
Authors: Egan Paul , Cagan Jonathan , Schunn Christian , LeDuc Philip , Moore Jeffrey , Chiu Felix
Published: January 2016

New opportunities in design often surface with scientific advances, however, the rapid pace of scientific findings in biological domains, and their complexity, may impede effective technological design. This paper addresses such challenges through weaving phases of scientific discovery, analytical description, and technological design in an integrative “d3 Methodology.” The method is implemented using human-guided automated processes developed with cognitive-based considerations. A case study of designing myosin bio-libraries is specifically investigated, and optimization results suggest that bio-libraries of designed synthetic isoforms have advantages over natural isoforms. The findings are motivating for future scientific endeavors to investigate the benefits of designed myosins, thus demonstrating reciprocity among design and science. The successes in implementing each d3 phase suggests the methodology is a feasible approach for nanoscale biosystems design, and is well-suited for driving the scientific inquiries of today towards the novel technologies of tomorrow.
A Compliant Mechanism Design for Refreshable Braille Display Using Shape Memory Alloy
Authors: Sapra Pulkit , Parsurampuria Ankit Kumar , Gupta Dhruv , Muralikrishnan Suman , Raj Mayank , Anand Akash , Darda Vinit , Paul Rohan , Balakrishnan M. , Rao P. V. M.
Published: January 2016

Refreshable Braille Display (RBD) is a device that enables people with visual imparity to read digital text through tactile interface. Braille literacy is essential for empowerment of visually impaired people and offers several advantages over auditory aids. Commercially available RBDs have not been able to penetrate the market due to their high cost. Shape memory alloy (SMA) based Braille display is a low cost alternative but faces the challenge of high power consumption, heat accumulation and low refresh rate. This paper discusses the design, analysis and experimental validation of a cantilever based compliant mechanism for SMA based RBD to solve these issues.
Symbolic Computation of Quantities Associated With Time-Periodic Dynamical Systems
Authors: Kirkland W. Grant , Sinha S. C.
Published: January 2016

Many dynamical systems can be modeled by a set of linear/nonlinear ordinary differential equations with periodic time-varying coefficients. The state transition matrix Φ(t,α) associated with the linear part of the equation can be expressed in terms of the periodic Lyapunov-Floquét transformation matrix Q(t,α) and a time-invariant matrix R(α). Computation of Q(t,α) and R(α) in a symbolic form as a function of system parameters α is of paramount importance in stability, bifurcation analysis, and control system design. In the past, a methodology has been presented for computing Φ(t,α) in a symbolic form, however Q(t,α) and R(α) have never been calculated in a symbolic form. Since Q(t,α) and R(α) were available only in numerical forms, general results for parameter unfolding and control system design could not be obtained in the entire parameter space. In this work a technique for symbolic computation of Q(t,α), and R(α) matrices is presented. First, Φ(t,α) is computed symbolically using the shifted Chebyshev polynomials and Picard iteration method as suggested in the literature. Then R(α) is computed using the Gaussian quadrature integral formula. Finally Q(t,α) is computed using the matrix exponential summation method. Using Mathematica, this approach has successfully been applied to the well-known Mathieu equation and a four dimensional time-periodic system in order to demonstrate the applications of the proposed method to linear as well as nonlinear problems.
Refined Theoretical Modeling of a New-Generation Pressure-Operated Soft Snake
Authors: Luo Ming , Pan Yixiao , Tao Weijia , Chen Fuchen , Skorina Erik H. , Onal Cagdas D.
Published: January 2016

Our pressure-operated soft snake robot promises inherent flexibility and versatility to operate on complex and unpredictable environments compared to traditional snake robots made of rigid linkage chains. We previously presented a theoretical framework to describe its unique dynamic behavior and experimentally verified the accuracy of this model. This previous work had some drawbacks; the maximum center of mass velocity of the previous soft snake was one tenth its body length per second and the dynamic model could not predict the behavior of the robot when following non-linear trajectories because of a lack of frictional torques. In this paper we introduce the next generation of our soft robotic snake we call the “WPI SRS”, which can locomote ten times faster than the previous version. Additionally, we present refinements to the dynamical model that can predict both linear and rotational motions of the robot. Finally, we demonstrate the accuracy of this refined model through experimentation.
Module Design and Functionally Non-Isomorphic Configurations of the Hex-DMR II System
Authors: Davis Joshua D. , Sevimli Yunuscan , Eldridge Baxter R. , Chirikjian Gregory S.
Published: January 2016

Modular robots have sustained the interest of the robotics community over the past several years. In particular, many modular robotic systems are reconfigurable, robust against faults, and low-cost due to mass production of a small number of homogeneous modules. Faults in these systems are normally tolerated through redundancy or corrected by discarding damaged modules which reduces the operational capabilities of the robot. To overcome these difficulties, we developed and discussed the general design constraints of a heterogeneous modular robotic system (Hex-DMR II) capable of autonomous team repair and diagnosis. In this paper, we discuss the design of each module, in detail, and present a new, novel elevator module. Then, we introduce a forest-like structure that enumerates every non-isomorphic, functional agent configuration of our system. Finally, we present a case study contrasting the kinematics and power consumption of two particular configurations during a mapping task.
A Simulation-Driven Graph Grammar Method for the Automated Synthesis of Passive Dynamic Brachiating Robots
Authors: Stöckli Fritz R. , Shea Kristina
Published: January 2016

Topologic configurations of passive dynamic locomotion robots are usually designed manually by human designers and often bio-inspired. However, it is possible that, among the large number of possible configurations, some valid solutions to the problem exist that are potentially superior to existing solutions and, at the same time, different from bio-inspired or otherwise intuition-inspired configurations, and thus not likely discovered without an automated design method. This paper addresses the problem of the automated design of passive dynamic systems in general by introducing a graph grammar based method that integrates dynamic simulation to evaluate and evolve configurations. In particular, the method is shown to find different, new solutions to the problem of the design of two-dimensional passive dynamic continuous contact brachiating robots. Brachiating is the swinging locomotion of primates moving from one tree branch to the next. The presented graph grammar rules preserve system properties among robot topologies, which makes it possible to maintain the necessary symmetry of the brachiating configurations. A separation of parametric optimization and topologic synthesis actions is proposed for the synthesis of passive dynamic systems. Compared to research on automated synthesis of robot topologies that use dynamic simulation to evaluate actuated and controlled robotic systems, this paper contributes a method to automatically generate alternative topologies for passive dynamic systems, which do not draw energy from a power source.
Reducing Sketch Inhibition During Concept Generation: Psychophysiological Evidence of the Effect of Interventions
Authors: Hu Wan-Lin , Booth Joran , Reid Tahira
Published: January 2016

This research investigated the effect of warm-up activities on cognitive states during concept generation. Psychophysiological tools including electroencephalography (EEG) and galvanic skin response (GSR) were used along with self-report measures (NASA TLX). Participants were divided into 3 test conditions: 1) no warm-up activity; 2) simple warm-up activities; 3) sketch-inhibition reducing activities. All participants did the same short design task. Results show that those who did a warm-up prior to ideation had a decrease in stress, especially for those who were personally familiar with the design problem. The art activities especially improved engagement for younger participants. We also saw that females who used the art-based activities reported lower mental workload during ideation and greater pride in their sketches. However, the warm-ups did not produce any difference in the number of ideas or other metrics of performance. These preliminary results indicate that warm-up activities, especially the art-based ones, help reduce inhibition by calming the cognitive state.
Parameter Design Strategies: A Comparison Between Human Designers and the Simulated Annealing Algorithm
Authors: Yu Bo Yang , de Weck Olivier , Yang Maria C.
Published: January 2016

Computer-based tools have great potential for facilitating the design of large-scale engineering systems. Interviews with veteran designers of desalination systems revealed that they tended to employ a trial-and-error approach to determine critical design parameters when using software design packages. A series of human experiments were conducted to observe the performance and behavior of test subjects during a series of simulated design processes involving seawater reverse osmosis (SWRO) plants. The subjects were mostly students with a spectrum of knowledge levels in desalination system design. The experiments showed that subjects who ranked top in performance behaved very differently from those who were bottom-ranked. The problem-solving profiles of the best performing subjects resembled a well-tuned simulated annealing optimization algorithm while the worst performing subjects used a pseudo random search strategy. This finding could be used to improve computer-based design tools by utilizing the synergy between strengths of humans and computers.
Teaching Students to Innovate: Evaluating Methods for Bioinspired Design and Their Impact on Design Self Efficacy
Authors: Durand Fabien , Helms Michael E. , Tsenn Joanna , McTigue Erin , McAdams Daniel A. , Linsey Julie S.
Published: January 2016

Bioinspired design is becoming an increasingly popular approach that makes use of nature as a source of inspiration to develop designs. Tools and methods are currently being evaluated to determine how designers may best leverage biological systems to generate designs. In this paper we present a study in an engineering elective course at Texas A&M University that explores the effects of five different methods for bioinspired design on the quality and quantity of ideas generated, student self-efficacy, as well as student feedback. These methods include Directed, Case Study, the use of AskNature.org, BioTRIZ, and Functional Modeling. We show that each of the methods produces numerous effective and creative solutions, with a high quality and quantity of ideas. We also show that the methods utilized to teach bioinspired design methods positively affect the students’ design confidence, outcome expectancy and anxiety, while also preserving students’ high motivation towards engineering design. Finally, we identify potential areas for improvement for the methods and the course.
Loaded Versus Unloaded Gait Balance Stability: A Measure of Dynamic Walking
Authors: Mummolo Carlotta , Park Sukyung , Mangialardi Luigi , Kim Joo H.
Published: January 2016

Several stability indices exist in the literature, each within their contexts and perspectives of quantification. However, no relevant index for the quantification of gait balance stability has been rigorously developed. Here, the novel Dynamic Gait Measure (DGM) is used to characterize the distinct gait balance stability of loaded walking, as compared to normal human walking. The DGM quantifies the normalized effects of inertia of a given gait with respect to the time-varying foot support region. The DGM is formulated in terms of the gait parameters reflecting a given gait strategy, and is extended to multiple steps of the gait cycle. The altered gait kinematics observed during load carriage (decreased single support duration, inertia effects, and step length) results in decreased DGM values (p < 0.0001), indicating that loaded walking is more statically stable compared with the unloaded walking. The DGM is compared with other common gait stability indices to validate its unique ability to catch the alteration (due to load carriage) in its corresponding gait stability characteristics.
Analysis and Design of a Remote Center Compliance Universal Joint
Authors: Dubois Pierre-Olivier , Birglen Lionel
Published: January 2016

This paper presents a novel mechanical design of a lower mobility remote center compliance linkage. This mechanism consists in three platforms connected by three legs with universal joints. Two of these platforms are attached to the ground while last one is the mobile platform. Using screw theory, it is first demonstrated that this mechanism allows its mobile platform to rotate around a fixed point in space without having a joint directly connected to this point. Indeed, knowing the mobility of the two former platforms, it is possible to define a wrench system for each leg and thus, find the reciprocal twist system of the mobile platform. Then, the results of the optimization of the mechanism’s design through a genetic algorithm is presented using the conditioning of its Jacobian matrix as a criterion. Finally, a compliant version of the mechanism is developed and a finite element analysis (FEA) simulation demonstrates the proper mobility of the system under typical loading scenarios.
Design and Development of a Novel Soft-and-Rigid Hybrid Actuator System for Robotic Applications
Authors: Haghshenas-Jaryani Mahdi , Carrigan Wei , Wijesundara Muthu B. J.
Published: January 2016

This paper presents the design and development of a pneumatic soft-and-rigid hybrid actuator system that consists of half-bellow shaped soft sections in-between block shape rigid sections. The hybrid actuator architecture allows for selective actuation of each soft section (acting as a joint) with precise control over its bending motion. The soft half-bellow section is designed as a series of hollow ridges extending straight to a flat base. This geometry provides forward and backward bending motion when subjected to positive and negative pressure, respectively. Bending occurs as the ridges of the soft section expand and contract more than the flat base due to pressure variations. The rigid sections serve as connections between soft actuator sections and enhance force transfer. As a case study, a hybrid actuator system was designed as a soft robotic digit with three soft joints and four rigid connecting sections. Finite element analysis was performed to evaluate the design parameters such as number of ridges and materials for the robotic finger. The joints (from proximal to distal) were designed to have four, three, and two ridges, respectively, to generate the desired range of angular motion. Fabrication of the finger was done with silicone rubber RTV-4234-T4 and PMC polyurethane rubber using a combination of compression molding and overmolding processes. The angular and translational displacements of the robotic finger were experimentally and numerically evaluated at different pressures. The trajectory of the fingertip is comparable to those reported in literature for continuous soft actuators with a similar length. The significance of this actuator system is that both range of angular and translational motions are achieved at low pressure, less than 70kPa, as opposed to reported pressures of greater than 100kPa. The presented results show the great potential of the soft robotic finger for use in robotic, rehabilitation, and assistive device applications.
Multi Rigid-Body Contact Dynamics With Regularized Friction
Authors: Gholami Farnood , Nasri Mostafa , Kövecses József
Published: January 2016

A novel mathematical formulation in terms of a linear complementarity problem is introduced for multibody contact problems. In this approach, contacts are characterized based on kinematic constraints while the friction forces are simultaneously regularized and incorporated into the formulation. The variables of the resulting linear complementarity problem are only the normal forces. The main advantage of this formulation is a significant dimension reduction in the resulting linear complementarity problem in comparison with its counterpart formulations in the literature. Moreover, the dimension can be even further reduced by removing the velocity variables from the formulation. The proposed formulation is examined for benchmark examples yielding promising results.
Web-Based Computing in C/C++
Authors: Wong Nathan , Gucwa Kevin , Cheng Harry H.
Published: January 2016

An interactive, web-based C/C++ computing environment has been developed to facilitate programming education. An editor with syntax highlighting is provided for students to solve the educational lessons designed to introduce computer programming concepts. The system uses SafeCh, a secure C/C++ interpreter that sandboxes the user to protect against server access, to execute code written by the user. Node.js, a JavaScript framework, is used to interface with SafeCh to redirect user input and output data from client to server and vice versa, creating an interactive programming environment. Users are able to access the learning environment conveniently using any internet-enabled device, including mobile phones and tablets. Most other web-based interactive programming tutorials teach scripting languages such as Python or JavaScript. The few existing web tutorials for C/C++ use server-side compilation and thus lack the same interactivity as is available with this system. Given the increasing popularity of programming education events such as Hour of Code, this web-based computing system can be a simple, interactive method to introduce and teach C/C++.
Manufacturing Functionally Gradient Material Objects With an Off the Shelf 3D Printer: Challenges and Solutions
Authors: Garland Anthony , Fadel Georges
Published: January 2016

This paper presents the challenges and solutions encountered while printing functionally gradient material (FGM) objects using an off the shelf Fused Deposition Modeling (FDM) 3D printer. The printer, Build Builder Dual-Feed Extruder from 3dprinter4u, has the unique design of extruding two different filaments out of one nozzle. Two separate motors independently pull two different filaments into one chamber causing plastic to extrude out of one nozzle. By using different filaments with different properties, an object with a material properties gradient can be manufactured. These material property gradients can help minimize the difficulty of bonding two different materials directly to each other, and give the designer the ability to tailor individual regions of one object to have different physical properties. Finding an optimal object design that can take advantage of this gradation is a unique problem that goes beyond the traditional solid modeling found in most CAD software. Once a design is obtained, slicing the object and creating an optimal build path is challenging because the gradation must be considered. Several objects were designed and manufactured to test the printers ability to print FGM objects. The python code used to add gradient change commands to the existing Gcode, and to slice a FGM flywheel while taking into account the material gradation has been made open source.
A Practical Method to Predict Total Fatigue Life of Welded Joints Structures
Authors: Gao Huiying , Zhu Shun-Peng , Lv Zhiqiang , Zuo Fang-Jun , Huang Hong-Zhong
Published: January 2016

Welded joints are usually the weakest link for welded structures due to the existence of stress concentration caused from welding. Fracture mechanics-based approach is a main method used to predict fatigue life for welded joints structures. In engineering, there are two main problems in fatigue life prediction, one is whether crack initiation life can be ignored or not, and the other one is to determine the crack size starting to propagate. Based on this research, a practical procedure is proposed to predict fatigue life of welded joints structures using an initial crack life model and Paris law. Emphasis is put on the discussion about crack initiation life and how to choose an appropriate method to determine the initial crack size. Noted that the proposed method in this paper does not need any tests to determine crack initiation life when crack size reaches a specified value, which depends on experience and is considered as crack size starting to propagate, thus human factors and uncertainty can be minished. Through comparison analysis, fatigue life predictions based on the proposed method are in a good agreement with experimental data.
Analytic Determination of Wrench Closure Workspace of Spatial Cable Driven Parallel Mechanisms
Authors: Sheng Zhiyu , Park Joon-Hyuk , Stegall Paul , Agrawal Sunil K.
Published: January 2016

This paper proposes an efficient way of determining analytically the Wrench Closure Workspace (WCW) of spatial redundant cable-driven parallel mechanisms (CDPM). The method builds upon the boundary surface equations obtained from the null space of the structure matrix of CDPM. The set of feasible solutions is obtained that satisfies positive tension in the cables. This method was applied to characterize the WCW of spatial CDPM which has redundancy of 1 or 2. A simulation study was carried out to validate the accuracy and efficiency of the method. Several advantages over conventional approaches for determining the WCW were identified through simulation.
Topology Optimization of Gearbox to Reduce Radiated Noise
Authors: Wang J. P. , Liu G. , Chang S. , Wu L. Y.
Published: January 2016

In this paper, topology optimization of gearbox to reduce the radiated noise is studied based on the analysis of modal acoustic contribution and panel acoustic contribution. Firstly, the bearing dynamic loads are obtained by solving the dynamic equations of gear system. Secondly, the vibration of gearbox is calculated using FEM and the radiated noise is simulated using BEM by taking these bearing dynamic loads as excitations. Thirdly, the panel having larger contribution to the sound pressure level (SPL) at a specific field point is found by panel acoustic contribution analysis (PACA), and this panel is taken as design domain. The mode order with larger contribution is determined by modal acoustic contribution analysis (MACA), and making corresponding natural frequency becomes far away from excited frequency is taken as a constraint. Finally, the topology optimization of gearbox is completed using SIMP method, and the ribs are arranged according to the optimization results. The results show that the equivalent sound pressure level at objective field point can be reduced obviously by using this method.
Efficient and Robust Implementation of the TLISMNI Method
Authors: Aboubakr Ahmed , Shabana Ahmed A.
Published: January 2016

The dynamics of large scale and complex multibody systems (MBS) that include flexible bodies and contact/impact pairs is governed by stiff equations. Because explicit integration methods can be very inefficient and often fail in the case of stiff problems, the use of implicit numerical integration methods is recommended in this case. This paper presents a new and efficient implementation of the two-loop implicit sparse matrix numerical integration (TLISMNI) method proposed for the solution of constrained rigid and flexible MBS differential and algebraic equations. The TLISMNI method has desirable features that include avoiding numerical differentiation of the forces, allowing for an efficient sparse matrix implementation, and ensuring that the kinematic constraint equations are satisfied at the position, velocity and acceleration levels. In this method, a sparse Lagrangian augmented form of the equations of motion that ensures that the constraints are satisfied at the acceleration level is first used to solve for all the accelerations and Lagrange multipliers. The generalized coordinate partitioning or recursive methods can be used to satisfy the constraint equations at the position and velocity levels. In order to improve the efficiency and robustness of the TLISMNI method, the simple iteration and the Jacobian-Free Newton-Krylov approaches are used in this investigation. The new implementation is tested using several low order formulas that include Hilber–Hughes–Taylor (HHT), L-stable Park, A-stable Trapezoidal, and A-stable BDF methods. The HHT method allow for including numerical damping. Discussion on which method is more appropriate to use for a certain application is provided. The paper also discusses TLISMNI implementation issues including the step size selection, the convergence criteria, the error control, and the effect of the numerical damping. The use of the computer algorithm described in this paper is demonstrated by solving complex rigid and flexible tracked vehicle models, railroad vehicle models, and very stiff structure problems. The results, obtained using these low order formulas, are compared with the results obtained using the explicit Adams-Bashforth predictor-corrector method. Using the TLISMNI method, which does not require numerical differentiation of the forces and allows for an efficient sparse matrix implementation, for solving complex and stiff structure problems leads to significant computational cost saving as demonstrated in this paper. In some problems, it was found that the new TLISMNI implementation is 35 times faster than the explicit Adams-Bashforth method.
SIMS measurement of hydrogen and deuterium detection limits in silicon: Comparison of different SIMS instrumentation
Authors: Stevie Fred A. , Zhou Chaunzhen , Hopstaken Marinus , Saccomanno Michael , Zhang Zhichun , Turansky Andrew
Published: January 2016

Hydrogen is the most abundant element in the universe, but it cannot be detected by many analytical techniques. This element is used to improve interface quality and reduce the impact of defects in silicon technology. Knowledge of the amount and distribution of hydrogen is of significant interest for many technologies, such as ZnO and glass manufacturing. Secondary ion mass spectrometry (SIMS) can provide analysis for hydrogen and the isotopes deuterium and tritium. Lower instrument vacuum will improve the hydrogen detection limit. Vacuum conditions can be optimized by methods such as overnight pumping of samples and sample holder heating. Adsorption of hydrogen from the vacuum environment during analysis can be minimized with use of high sputtering rate. The species monitored may be atomic or molecular, such as H− or Cs2H+. The latter species provides a practical means for hydrogen profiling in dielectric films in magnetic sector instruments with conventional charge compensation. It is of interest to compare the detection limit that can be obtained for various SIMS instrument configurations under typical operating conditions. Time of flight, magnetic sector, and quadrupole analyzers were used to analyze hydrogen and deuterium ion implanted silicon. The detection limits varied for the different analyzers used and were in the 1018–1019 atoms/cm3 range for hydrogen and as low as 1016 atoms/cm3 for deuterium.
Growth of free-standing wurtzite AlGaN by MBE using a highly efficient RF plasma source
Authors: Novikov Sergei V. , Staddon Chris R. , Whale Josh , Kent Anthony J. , Foxon C. Thomas
Published: January 2016

Ultraviolet light emitting diodes (UV LEDs) are now being developed for various potential applications including water purification, surface decontamination, optical sensing, and solid-state lighting. The basis for this development is the successful production of AlxGa1−xN UV LEDs grown by either metal-organic vapor phase epitaxy (MOVPE) or molecular beam epitaxy (MBE). Initial studies used mainly sapphire as the substrate, but this result in a high density of defects in the epitaxial films and now bulk GaN or AlN substrates are being used to reduce this to acceptable values. However, the lattice parameters of GaN and AlN are significantly different, so any AlGaN alloy grown on either substrate will still be strained. If, however, AlGaN substrates were available, this problem could be avoided and an overall lattice match achieved. At present, the existing bulk GaN and AlN substrates are produced by MOVPE and physical vapor transport, but thick free-standing films of AlGaN are difficult to produce by either method. The authors have used plasma-assisted MBE to grow free-standing AlxGa1−xN up to 100 μm in thickness using both an HD25 source from Oxford Applied Research and a novel high efficiency source from Riber to provide active nitrogen. Films were grown on 2- and 3-in. diameter sapphire and GaAs (111)B substrates with growth rates ranging from 0.2 to 3 μm/h and with AlN contents of 0% and ∼20%. Secondary ion mass spectrometer studies show uniform incorporation of Al, Ga, and N throughout the films, and strong room temperature photoluminescence is observed in all cases. For films grown on GaAs, the authors obtained free-standing AlGaN substrates for subsequent growth by MOVPE or MBE by removing the GaAs using a standard chemical etchant. The use of high growth rates makes this a potentially viable commercial process since AlxGa1−xN free-standing films can be grown in a single day and potentially this method could be extended to a multiwafer system with a suitable plasma source.
An acoustic study of multiple lateral consonants in three Central Australian languages
Authors: Tabain Marija , Butcher Andrew , Breen Gavan , Beare Richard
Published: January 2016

This study presents dental, alveolar, retroflex, and palatal lateral /̪ll ɭ ʎ/ data from three Central Australian languages: Arrernte, Pitjantjatjara, and Warlpiri. Formant results show that the laminal laterals (dental /̪l/ and palatal /ʎ/) have a relatively low F1, presumably due to a high jaw position for these sounds, as well as higher F4. In addition, the palatal /ʎ/ has very high F2. There is relatively little difference in F3 between the four lateral places of articulation. However, the retroflex /ɭ/ appears to have slightly lower F3 and F4 in comparison to the other lateral sounds. Importantly, spectral moment analyses suggest that centre of gravity and standard deviation (first and second spectral moments) are sufficient to characterize the four places of articulation. The retroflex has a concentration of energy at slightly lower frequencies than the alveolar, while the palatal has a concentration of energy at higher frequencies. The dental is characterized by a more even spread of energy. These various results are discussed in light of different acoustic models of lateral production, and the possibility of spectral cues to place of articulation across manners of articulation is considered.
Effects of relative and absolute frequency in the spectral weighting of loudness
Authors: Joshi Suyash Narendra , Wróblewski Marcin , Schmid Kendra K. , Jesteadt Walt
Published: January 2016

The loudness of broadband sound is often modeled as a linear sum of specific loudness across frequency bands. In contrast, recent studies using molecular psychophysical methods suggest that low and high frequency components contribute more to the overall loudness than mid frequencies. In a series of experiments, the contribution of individual components to the overall loudness of a tone complex was assessed using the molecular psychophysical method as well as a loudness matching task. The stimuli were two spectrally overlapping ten-tone complexes with two equivalent rectangular bandwidth spacing between the tones, making it possible to separate effects of relative and absolute frequency. The lowest frequency components of the “low-frequency” and the “high-frequency” complexes were 208 and 808 Hz, respectively. Perceptual-weights data showed emphasis on lowest and highest frequencies of both the complexes, suggesting spectral-edge related effects. Loudness matching data in the same listeners confirmed the greater contribution of low and high frequency components to the overall loudness of the ten-tone complexes. Masked detection thresholds of the individual components within the tone complex were not correlated with perceptual weights. The results show that perceptual weights provide reliable behavioral correlates of relative contributions of the individual frequency components to overall loudness of broadband sounds.
Spotlight on Athletes with a Disability: Malaysian Newspaper Coverage of the 2012 London Paralympic Games
Authors: Cheong Jadeera Phaik Geok , Khoo Selina , Razman Rizal
Published: January 2016

This study analyzed newspaper coverage of the 2012 London Paralympic Games by 8 Malaysian newspapers. Articles and photographs from 4 English-language and 4 Malay-language newspapers were examined from August 28 (1 day before the Games) to September 10, 2012 (1 day after the Games closing). Tables, graphs, letters, fact boxes, and lists of events were excluded from analysis. A total of 132 articles and 131 photographs were analyzed. Content analysis of the newspaper articles revealed that most (62.8%) of the articles contained positive reference to the athletes with a disability. There were equal numbers (39.1%) of action and static shots of athletes. More articles and photographs of Malaysian (58%) than non-Malaysian (42%) athletes with a disability were identified. Only 14.9% of the articles and photographs were related to female athletes with a disability.
Barriers and Facilitators for Generalizing Cycling Skills Learned at Camp to Home
Authors: Temple Viviene A. , Purves P. Lynn , Misovic Robyn , Lewis Coral J. , DeBoer Carrie
Published: January 2016

Many children with disabling conditions do not acquire the skills to successfully ride a 2-wheeled bicycle. The aim was to describe cycling patterns before and after an innovative learn-to-ride bike camp and factors that facilitate or hinder the generalization of skills developed at camp to home. Parents and children participated in semistructured interviews 3–4 mo postcamp. Transcripts were examined deductively for participation and contextual influences using a template of codes approach. None of the children were successfully riding a 2-wheeled bicycle before camp. Two patterns of participation were evident from narrative descriptions of postcamp riding: “riders” and “not there yet.” Major facilitating factors were the camp itself, the interaction between the camp and the health service, and continued parent involvement. The program transferred well to home for children who were riding independently on the last day of camp. Ongoing support is needed for children “not there yet.”
Erratum for the article by Haegele et al in APAQ 32(3)
Authors: Haegele Justin A. , Lee Jihyun , Porretta David L.
Published: January 2016

In the article by Haegele, J.A., Lee, L., and Porretta, D.L., “Research trends in Adapted Physical Activity Quarterly from 2004 to 2013”, in Adapted Physical Activity Quarterly, 32(3), 187–205, an incorrect DOI was printed. The correct DOI for that article is http://dx.doi.org/10.1123/APAQ.2014-0232.
Purinergic P2Y
6
receptors heterodimerize with angiotensin AT1 receptors to promote angiotensin II–induced hypertension
Authors: Nishimura Akiyuki , Sunggip Caroline , Tozaki-Saitoh Hidetoshi , Shimauchi Tsukasa , Numaga-Tomita Takuro , Hirano Katsuya , Ide Tomomi , Boeynaems Jean-Marie , Kurose Hitoshi , Tsuda Makoto , Robaye Bernard , Inoue Kazuhide , Nishida Motohiro
Published: January 2016

Aging changes the response of blood vessels to angiotensin II, contributing to hypertension.
ESCRT proteins restrict constitutive NF-κB signaling by trafficking cytokine receptors
Authors: Mamińska Agnieszka , Bartosik Anna , Banach-Orłowska Magdalena , Pilecka Iwona , Jastrzębski Kamil , Zdżalik-Bielecka Daria , Castanon Irinka , Poulain Morgane , Neyen Claudine , Wolińska-Nizioł Lidia , Toruń Anna , Szymańska Ewelina , Kowalczyk Agata , Piwocka Katarzyna , Simonsen Anne , Stenmark Harald , Fürthauer Maximilian , González-Gaitán Marcos , Miaczynska Marta
Published: January 2016

Proteins required for trafficking internalized cytokine receptors prevent the spurious activation of NF-κB signaling.
Papers of note in
Science Translational Medicine
Authors: Gough Nancy R.
Published: January 2016

This week’s articles feature insights into diacylglycerol kinase in the immune disorder XLP-1, allergy in infants, and the neurological disease fragile X syndrome.
Emergent repair of bronchial transection: both right and left main bronchial lung ventilation at surgery makes it easy for all
Authors: Dash Vedarth , Mahajan Jai Kumar , Yhosho Enono , Randhawa Jaskiran Singh
Published: January 2016

Maintaining adequate gas exchange is crucial during surgical repair of tracheobronchial injuries in children and reflects the skills of the anaesthetist and the surgeon. We present a 7-year-old girl who underwent urgent repair of the bronchial transection and novel use of ventilation of the transected lung helped accomplish the repair successfully.
Pyoderma gangrenosum induced by episiotomy
Authors: Alani Angela , Sadlier Muriel , Ramsay Bart , Ahmad Kashif
Published: January 2016

We present a patient who developed genital ulceration within hours following episiotomy procedure during a normal vaginal delivery. This was initially treated by the gynaecology and medical team as cellulitis with no improvement. A diagnosis of pyoderma gangrenosum (PG) was made by the dermatology team 12 days later. On further investigation, she was found to be hepatitis C positive. We report this case to highlight the phenomenon of pathergy and frequent misdiagnosis of PG by other medical teams. When a postsurgical wound is not healing despite relevant systemic treatment, the clinician should suspect PG as an early diagnosis and treatment is crucial.
Uveitis-glaucoma-hyphaema syndrome with in-the-bag placement of intraocular lens
Authors: Badakere Swathi Vallabh , Senthil Sirisha , Turaga Kiranmaye , Garg Prashant
Published: January 2016

Uveitis-glaucoma-hyphaema (UGH) syndrome is commonly reported following intraocular lens (IOL) implantation in the anterior chamber or malpositioned posterior chamber IOLs. It is extremely rare to have this complication in an eye with intact posterior capsule and a well placed in-the-bag IOL. We report a case of a 48-year-old man who presented with blurred vision after an uneventful cataract surgery in the right eye, and who was treated for anterior uveitis. The anterior chamber inflammation persisted despite intense treatment with topical steroids for 2 months, and the intraocular pressure was high. The posterior chamber IOL was in the bag and well covered by a capsulorrhexis margin. Dilated gonioscopy revealed inferior capsular bag hyphaema secondary to the superior haptic displacement due to a tear in the equatorial bag. Our case highlights the importance of dilated gonioscopy and a rare possibility of UGH syndrome in an eye with a well-placed IOL.