bluuebunny/crossref_metadata_2025_split huggingface dataset:
Finite Element-Based Numerical Investigations of a Beamlike Actuator Combining Shape Memory and Superelastic Effects
Authors: Reis Danillo C. , Rade Domingos A. , Santos Osmar S. 
Published: December 2019

Abstract
It has been amply demonstrated that the development of SMA actuators has a great potential of application in several branches of industry. Obviously, the efficiency of the actuators depends both on the inherent features of the materials they are made of and the geometric characteristics of the devices. This work considers a particular type of actuator first conceived by [1], consisting in the association of two cantilever beams, the first presenting the shape memory effect and the second presenting the superelastic effect, coupled mechanically so as to guarantee two equilibrium positions and thus a stand-alone cyclic actuator, in which the superelastic beam provides the bias action. Numerical simulations of the behavior of the actuator are performed using the commercial finite element software COMSOL, which implements the Boyd-Lagoudas thermomechanical model. The goal of the simulations is to characterize the actuation range of the actuator, in terms of maximum displacement obtained at the tip. The effect of the dimensions of the beams on the tip displacement under some load scenarios is investigated. The results provide guidelines for the design of the actuator to fulfill specific requirements, also suggesting the use of numerical optimization for the optimal design of the actuator accounting for constraints.
Control of Brake Squeal Using Shunted Piezoelectric Pads
Authors: Abdullah Yaqoub , Baz Amr 
Published: December 2019

Abstract
Brake squeal phenomenon poses serious challenges to the automotive industry due to its technical complexity and the pressing need for mitigating its undesirable effects. More importantly, brake squeal causes significant customer dissatisfaction and adversely affects the subjective quality of the vehicles. These effects have substantial economic impact on the automotive industry. Furthermore, it is essential to properly treat the brake squeal problems in order to avoid unexpected catastrophic failure of the brake system.
In this paper, it is proposed to mitigate the brake squeal problems by providing the brake pads with piezoelectric patches which are shunted by properly tuned electric networks. The shunted piezoelectric pads offer a unique ability to convert the mechanical energy induced by the brake squeal into electrical energy which can be dissipated into the network in order to enhance the damping and stability characteristics of the brake system. Accordingly, it is envisioned that the proposed approach would enable the disc brake systems to operate over broad ranges of operating parameters without experiencing the adverse effects of brake squeal.
The proposed system is modeled by a simple two Degree-Of-Freedom (DOF) disc brake model. The structural DOF are integrated with the constitutive model of the shunted piezoelectric network in order to predict the threshold of brake squeal. The stability limits of the proposed brake system are established as a function of the design parameters of the shunted piezoelectric network. Numerical examples are presented to demonstrate the effectiveness of the proposed system in expanding the operating range of the brake system without experiencing squeal problems.
Application of the proposed system to a distributed disc brake system model is a natural extension of the present work.
A Three-Row Opposed Gripping Mechanism With Radial Configuration for Wall-Climbing Robots
Authors: Xie Chao , Wu Xuan , Wang Xiaojie 
Published: December 2019

Abstract
This paper presents a three-row opposed gripping mechanism with radial configuration for wall-climbing robots inspired by the structure of the gripper of LEMUR IIB. The mechanism builds upon a kind of microspines for climbing robots. This work utilizes an opposed spoke configuration with 3 rows of 31 microspines on each linkage array, splayed around a central bracket. A single motor drives the 3 linkage arrays by a set of gears to achieve attachment and detachment procedures, and the trajectory of each linkage array tip makes the miniature spines easy to penetrate in and pull off the surfaces. The mechanism designed as a foot of climbing robots can vertically resist at least 1kg of load on rough surface. The findings provide a foundation for constructing a system for a rough-wall-climbing robot.
Active Thermal Management of FRP Composites via Embedded Vascular Networks
Authors: Cole Jim , Bond Ian , Lawrie Andrew 
Published: December 2019

Abstract
Fibre-reinforced polymer (FRP) composite materials are limited in high temperature applications by the matrix glass transition temperature, Tg. At and above this temperature, significant mechanical performance is lost, and degradation processes accelerated. This research explores the use of internal passages, or vascules, within the laminate to carry a coolant fluid, absorbing heat energy and cooling the material. A custom thermal chamber and four-point flexural test fixture were developed to perform in-situ thermo-mechanical testing. Vascular and non-vascular carbon/epoxy specimens were manufactured, containing arrays of four 1.1 mm diameter vascules. Specimens were exposed to temperatures from ambient to 170 °C (Tg = 200 °C). Flexural modulus varied little with temperature across all tests. Non-vascular specimens at 170 °C showed a reduction in ultimate strength of 21 % compared to under ambient conditions. The presence of vascules caused a small improvement in flexural modulus and strength, due to displacement of a small number of 0° fibre tows further from the neutral axis as a result of the manufacturing process. At 15 L·min−1 coolant flow, vascular specimens showed full retention of strength compared to non-vascular specimens at ambient, demonstrating the potential mechanical performance benefits.
DNA Nanotechnologies for the Design of Bio-Inspired Soft Nanocomposites With Reversible Rigidity
Authors: Calais Theo , Stalin Thileepan , Joseph Vincent S. , Valdivia y Alvarado Pablo 
Published: December 2019

Abstract
Structures and mechanisms in soft robotics are primarily based on chemically versatile species such as hydrogels, polymers, or elastomers, thus offering great potential for the design of adaptive core properties. In particular, tunable rigidity is highly desirable to enable control of soft grippers or for advanced robot locomotion. However, most of the strategies explored so far rely on mechanisms, such as phase transitions or shape memory effects, that require heavy external hardware or have a limited range of tunable rigidity.
In this work, we propose a novel strategy inspired by the sea cucumber dermis mechanism. High aspect ratio carbon nanotubes (CNTs) are reversibly interconnected by DNA oligonucleotides within a polyacrylamide (PAAm) hydrogel. The combination of the excellent mechanical properties of CNTs and the reversible hybridization of DNA strands into a stable double-helicoidal structure allowed the reversible tunability of mechanical properties over one order of magnitude (from ∼100 Pa to ∼1 kPa) within minutes by increasing the temperature beyond the melting temperature of DNA strands (∼50 °C). First, the functionalization strategy of CNTs with DNA strands is described and characterized. The aggregation of CNTs driven by the DNA hybridization is then demonstrated. The mechanical properties of hydrogels functionalized with CNTs are finally analyzed using rheology measurements.
A Variable Camber Piezocomposite Trailing-Edge for Subsonic Aircraft: Multidisciplinary Design Optimization
Authors: Wright Cody , Bilgen Onur 
Published: December 2019

Abstract
A continuous-surface morphing airfoil is desirable for commercial aircraft in order to improve fuel efficiency, and due to the potential to morph the wing into a high-lift configuration for take-off and landing. Piezocomposite actuators have shown to be a feasible strategy for camber morphing in small unmanned fixed-wing aircraft with a Reynold’s number in the range of 50,000 to 250,000. As an extension, this paper presents a theoretical framework and results for morphing in single and multi-segment natural laminar flow airfoils with a maximum Reynold’s number of 825,000. The airfoils presented employ a continuous inextensible surface. To achieve morphing, piezocomposite actuating elements are applied on the suction and pressure surfaces of the airfoils. The geometric properties of the airfoils are determined using a genetic algorithm optimization method with a migration strategy in order to maintain population diversity. The algorithm optimizes independently the substrate thicknesses for the nominal airfoil, the leading edge, and the piezocomposite bonded surfaces. In addition, positions and voltages for each piezocomposite actuators are optimized. The genetic algorithm uses an objective function to maximize the change in coefficient of lift to morph the airfoil from its baseline (i.e. cruise) state to the high-lift state. Analysis is performed using a coupled fluid-structure interaction method assuming static aero-elastic behavior. Optimization is followed by a parametric analysis to examine lift, drag, and lift-to-drag ratio of the airfoils over their full operational range. The optimization is performed on a symmetric, asymmetric, and the aft element of a slotted multi-segment airfoil to examine the capabilities of induced-strain actuation at high dynamic pressures.
Miniaturized Broadband Vibration Energy Harvester With Piecewise-Linear Asymmetric Restoring Force
Authors: Masuda Arata , Zhao Feng 
Published: December 2019

Abstract
This paper presents a design study of a miniaturized broadband nonlinear vibration energy harvester (VEH) with piecewise-linear restoring force based on a mechanically-sprung resonator with stoppers. It is commonly recognized that a VEH based on a nonlinearly-sprung resonator can show broadband frequency characteristics while keeping its maximum power performance due to its bent resonance peak. The resonator to be investigated in this study consists of a magnet composite as a mass moving through an induction coil, two planar springs, and mechanical stoppers. The magnet composite is comprised of two repelling cylindrical magnets and a steel disk between them, all encapsulated in a thin stainless-steel cylinder. The planar springs with spiral-like shape are respectively connected to the both ends of the magnet composite so that they provide soft linear stiffness in a compact size. The mechanical stoppers installed to constrain the deformation of the spring give the resonator piecewise-linear hardening characteristics which effectively broaden the resonance band. In this study, the prototype VEH developed in the previous study is presented, and the gaps between the springs and stoppers are adjusted so that the resultant piecewise-linear restoring force shows symmetric or asymmetric property with respect to the equilibrium point. Experimental studies and analyses are carried out to examine the performance of the presented VEH in terms of the frequency response. The comparison of three different configurations of the stopper illustrates how the asymmetry in the bilinear restoring force affects the shape of the resonance peak. It is also suggested that the asymmetry may help the VEH operate in broader band by exploiting its ability of tailoring the resonance characteristics, which still needs further investigation.
Compact Telescopic Morphing Lattice Boom
Authors: McHale Ciarán , Telford Robert , Weaver Paul M. 
Published: December 2019

Abstract
This paper reports on the design and manufacture of a compact telescopic morphing lattice (CTML) space boom. This boom stows within a 1U CubeSat volume and weighs only 0.475kg. Once deployed, the CTML has a total length of 2m, 20 times the stowed height. The device consists of three multi-stable cylindrical composite lattices connected in series. To improve packaging efficiency, these lattices nest inside one another in the stowed configuration. The morphing lattice is a structure that uses prestress and lamina orientation to seamlessly morph from a short stowed state to a long deployed state. By tailoring the manufacturing parameters, the lattices in the boom have been designed to maximize the deployment force and to be self-deploying. Therefore, the CTML only requires a small, lightweight mechanism to regulate the deployment speed. The deployment speed regulator can also potentially retract the boom back to the stowed state, facilitating reconfigurability.
Target Shape Optimization of 3D Compliant Mechanism With Superelastic Joints and Shape Memory Actuation
Authors: Jovanova Jovana , Nastevska Angela , Frecker Mary 
Published: December 2019

Abstract
The shape memory effect and the superelasticity of nickel titanium (NiTi) alloys are beneficial for design of compliant mechanisms. The superelastic behavior of NiTi can be tailored for optimal flexure design in the compliant mechanism, allowing large deformation and shape change. The shape memory effect can also be utilized to actuate the compliant mechanism flexures enabling programing of the material to take on variety of shapes at different temperatures over time.
The compliant mechanism analyzed in this work is inspired from 3D multi leg spider-like locomotion, enabling movement in all directions by triggering different target shapes in time. The control of the material spatial distribution facilitated by additive manufacturing will enable tailored superelastic and shape memory behavior in the flexures of the multifunctional 3D compliant mechanism.
Design optimization and analyses as well as overall shape change are explored in this work. Superelastic joints are introduced as flexures to enable segment flexibility. The temperature change is used for actuation taking in consideration different initial strain conditions.
Memcapacitive Devices in Neuromorphic Circuits via Polymeric Biomimetic Membranes
Authors: Basham Colin , Pitz Megan , Najem Joseph , Sarles Stephen , Hasan Md Sakib 
Published: December 2019

Abstract
Two-terminal adaptive materials and circuit elements that mimic the signal processing, learning, and computing capabilities of biological synapses are essential for next-generation computing systems. To this end, we have recently developed resistive (ion channel) and capacitive (lipid bilayer) memory elements that mimic the composition, structure, and plasticity of biological synapses. Unlike solid-state counterparts, these biomolecular systems are low-power, analog, less noisy, biocompatible, and capable of exhibiting multiple timescales of short-term synaptic plasticity. However, lipid membranes lack structural stability and modularity necessary for a long-lasting adaptive material system. To address this issue, we propose the replacement of phospholipids with amphiphilic polymers to create artificial membranes, which have been demonstrated to be more durable than phospholipids. With the focus on memory capacitors, we demonstrate that polymeric bilayers can exhibit pinched hysteresis in the Q-v plane because of voltage-induced geometrical changes. Further, we demonstrate that the memcapacitive response is altered based on the surrounding oil medium; smaller oil molecules are retained at higher volume in the membrane, so that thicker bilayers have lower nominal capacitance but can vary this value by over 400%. Finally, we present a physics-based model that enables us to predict the device’s areal voltage-dependent response. Polymeric bilayers represent a significant enhancement in the field of soft-matter, geometrically-reconfigurable memcapacitors, and their highly customizable compositions will allow for a finely tuned electrical response that has a future in brain-inspired materials and circuits.
Nanocomposite Coating for Strain Monitoring
Authors: Magnafico Erika , Poli Francesco , Casalotti Arnaldo , Lanzara Giulia 
Published: December 2019

Abstract
In recent years carbon nanotubes (CNTs) have been widely used for the realization of polymeric matrix nanocomposites for strain monitoring applications in civil, biomedical and aerospace engineering. In fact, by embedding CNTs in an insulated polymer matrix, it is possible to realize a conductive nanocomposite with piezoresistive behaviour which allows to monitor the occurring strains through an electrical resistance change. In this work a conductive coating made of Multi-Walled Carbon Nanotubes (MWNTs) and PolymethylMethacrilate (PMMA) is fabricated and is applied onto a fiberglass structure surface. In order to characterize the electrical behaviour of the coating and its capability to sense strain, an experimental campaign is carried out by applying a voltage to the manufactured coating. Its variations throughout the surface in the longitudinal and transverse directions are then evaluated to identify the electric field distribution and its dependence on strain.
Exfoliated-Graphite/Latex Piezoresistive System for Mapping Plantar Pressure
Authors: Riegel Allison , Gray Jonathan , Zegeye Ephraim F. 
Published: December 2019

Abstract
Diabetics often have neuropathy that prevents them from noticing developing foot ulcers. Pressure sensors can detect areas with abnormally high pressure, allowing earlier detection, prevention, and treatment of developing ulcers. Accurate pressure sensors are often limited to bulky or stationary systems, or have other limitations such as lack of accuracy, slow response times, and cost. This paper explains the fabrication of a prototype system using a bilayer flexible sensor for better accuracy in measuring pressure. The sensor is made of an exfoliated graphite film on a latex substrate and is layered with rubber padding to allow deformation. It is connected to an electronic system that reads changing resistance due to pressure and maps the applied pressure. This system might be a low cost, accurate, and durable alternative to current systems.
Refractive change in children with accommodative esotropia
Authors: Bonafede Lucas , Bender Lloyd , Shaffer James , Ying Gui-shuang , Binenbaum Gil 
Published: December 2019

Objective
To determine whether there is a measurable change in hyperopia in children with accommodative esotropia over time.

Methods and analysis
A retrospective cohort of children with fully or partially accommodative esotropia diagnosed by age 7 years, followed to age 10 or older, and with at least two cycloplegic refractions, one before age 7 years and one after age 10 years. The annual change was calculated from linear mixed-effect models, overall and during two age periods with subgroup analysis by baseline refractive error (<4D, ≥4D) and type (partial, full) of accommodative esotropia.

Results
405 subjects were studied. Mean age at first and last visit was 3.2 and 12.1 years, respectively, with mean 7.6 cycloplegic refractions. The annual change (95% CI) in refractive error was −0.071 (−0.087 to –0.055) D/yr. Between ages 3 and 7, hyperopia among children with baseline hyperopia <4D increased by 0.12 (0.08 to 0.16) D/yr, while hyperopia among those with baseline 4D or greater was stable (0.0D/yr, −0.03 to 0.04) (p<0.001). Hyperopia decreased from age 7 to 15 years in both subgroups: <4D subgroup −0.17 (−0.20 to –0.14) D/yr, ≥4D subgroup −0.18 (−0.21 to –0.15) D/yr (p=0.58). There was no significant difference in refractive change between fully (n=274) and partially (n=131) accommodative esotropia (p≥0.10).

Conclusion
Hyperopia in children with accommodative esotropia is stable or increases up to age 7 years, depending on baseline hyperopia, but decreases gradually between ages 7 and 15 years regardless of baseline refractive error.
Characteristics and determinants of high-risk unscheduled return visits to the emergency department
Authors: Hiti Eveline A , Tamim Hani , Makki Maha , Geha Mirabelle , Kaddoura Rima , Obermeyer Ziad 
Published: December 2019

BackgroundHigh-risk unscheduled return visits (HRURVs), defined as return visits within 72 hours that require admission or die in the emergency department (ED) on representation, are a key quality metric in the ED. The objective of this study was to determine the incidence and describe the characteristics and predictors of HRURVs to the ED.MethodsCase–control study, conducted between 1 November 2014 and 31 October 2015. Cases included all HRURVs over the age of 18 that presented to the ED. Controls were selected from patients who were discharged from the ED during the study period and did not return in the next 72 hours. Controls were matched to cases based on gender, age (±5 years) and date of presentation.ResultsOut of 38 886 ED visits during the study period, 271 are HRURVs, giving an incidence of HRURV of 0.70% (95% CI 0.62% to 0.78%). Our final analysis includes 270 HRURV cases and 270 controls, with an in-ED mortality rate of 0.7%, intensive care unit admission of 11.1% and need for surgical intervention of 22.2%. After adjusting for other factors, HRURV cases are more likely to be discharged with a diagnosis related to digestive system or infectious disease (OR 1.64, 95% CI 1.02 to 2.65 and OR 2.81, 95% CI 1.05 to 7.51, respectively). Furthermore, presentation to the ED during off-hours is a significant predictor of HRURV (OR 1.64, 95% CI 1.11 to 2.43) as is the presence of a handover during the patient visit (OR 1.68, 95% CI 1.02 to 2.75).ConclusionHRURV is an important key quality outcome metric that reflects a subgroup of ED patients with specific characteristics and predictors. Efforts to reduce this HRURV rate should focus on interventions targeting patients discharged with digestive system, kidney and urinary tract and infectious diseases diagnosis as well as exploring the role of handover tools in reducing HRURVs.
Dealing with immune‐mediated haematological diseases in dogs and cats 1. Haemolytic anaemia
Authors: Whitley Nat 
Published: December 2019

Background: Immune‐mediated haemolytic anaemia (IMHA) is one of the more frequently encountered immune‐mediated diseases and one of the more common causes of severe anaemia in dogs and cats. Autoimmunity typically occurs due to a combination of genetic risk factors and environmental influences. Several dog breeds are predisposed, notably American and English cocker spaniels, springer spaniels, Old English sheepdogs, poodles, Irish setters and dachshunds. Prevalence within a breed may vary with geography and breed line.Aim of the article: This is the first article in a two‐part series on immune‐mediated haematological diseases in dogs and cats, and focuses on the diagnosis and management of IMHA. The second article, which will be published in the January/February 2020 issue of In Practice, will discuss immune‐mediated thrombocytopenia (IMT) and Evans syndrome (combined IMHA and IMT).