bluuebunny/crossref_metadata_2025 huggingface dataset:
Stochastic Vector Identification and Uncertain Modal Parameter Estimation for a Smart Composite Beam
Authors: Hios John D. , Fassois Spilios D.
Published: March 2009

This study aims at identifying the modal characteristics and their uncertainties for a smart
composite beam. The problem is addressed via Vector AutoRegressive with eXogenous excitation
(VARX) models. The advantages of VARX modeling include simplicity of implementation, high
accuracy, parsimony of representation, and capability of handling modal uncertainties. Two
different approaches to assess the modal parameter uncertainties are investigated. The first is based
upon linearizing the function that relates the VARX model parameters with the modal parameters,
whereas the second is based upon computer simulations using the Monte Carlo and the bootstrap
schemes. The results indicate that VARX modeling captures the system dynamics and provides
accurate modal parameters with tight confidence intervals.
Numerical Simulation for Concrete Structure Health Monitoring Based on Smart Piezoelectric Transducer Array
Authors: Yan Shi , Sun Wei
Published: March 2009

This paper presents results of numerical simulations for the health monitoring of a concrete
shear wall structure based on an impedance method applying the finite element method (FEM). The
concrete shear wall model pasted with PZT transducers array was established for the numerical
analysis. The PZT patches excited electrically at high frequency were used as transducers for
scanning and making data acquisition from signatures at both health and damaged stages of the shear
wall. The signatures from the patches located in the vicinity of the damage area were analyzed and
discovered to drastically change and those located at relatively far distance from the damage area
were less affected. The damages are quantified using an index named root mean square of the
deviation in signatures with respect to the baseline signature of the health state. At last, an
arrangement principle of the PZT transducers array is conceptually discussed in details.
Development of a Ferroelectric Shell Finite Element
Authors: Zouari Wajdi , Elhadrouz M. , Ben Zineb T.
Published: March 2009

Ferroelectricity is the non-linear behaviour exhibited by piezoelectric ceramics,
especially in the application of high electric field. Actually, the demand for numerical tools
taking into account this non linear phenomenon is increasing to reliably design applications
using piezoelectric ceramics. In this context, a shell finite element based on the
Reissner/Mindlin's theory and integrating a bi-dimensional macroscopic constitutive law for
domain switching effects (ferroelectricity) is developed. This element is implemented into the
finite element code ABAQUS using the subroutine UEL (User ELement). The
thermodynamical framework of the law is based on two scalar valued functions: the Helmoltz
free energy and an electric switching function. One internal variable (the remanent
polarization) is introduced and a non linear switching effect hardening is considered. An
implicit integration of the constitutive equations based on the return-mapping algorithm is
developed.
Wing Mechanization Design and Wind Tunnel Testing for a Perching Micro Air Vehicle
Authors: Lukens Jennifer M. , Reich Gregory W. , Sanders Brian
Published: March 2009

This paper describes the development of a mechanized wing concept for a perching
micro air vehicle. The wings are capable of rotating in pitch at two spanwise joints to simulate the
motion of a bird’s wings during a perching maneuver. This project focuses on the wing
mechanization design and analysis as well as the structure/mechanism integration. The advantage of
a perching type of landing is that it allows the vehicle to land with approximately zero vertical and
horizontal velocity on a tree branch, power line, or ledge. The requirements to perform this
maneuver were investigated, the structural design was developed, and the mechanization integration
to achieve this motion was determined. A model was designed and manufactured to demonstrate the
kinematic mechanism making this wing motion possible. Wind tunnel testing and analytical
simulation were also completed to further develop the model.
Microsystems Technologies for Use in Structures and Integrated Systems
Authors: Schönecker Andreas , Gebhardt Sylvia
Published: March 2009

Piezoceramics are considered as key functional material in micro systems and smart
structure technology. Showing superior mechanical, dielectric, pyroelectric, ferroelectric and
piezoelectric properties they introduce improved functionality, e.g. sensing, actuation, energy
harvesting, health monitoring or shape control. Various applications such as micro integrated
valves, drives, voltage converter, piezoelectric, pyroelectric and ultrasound sensors are expected.
Another field of application concerns active structures in space, automotive or machine building
industry. Progress was achieved by combining flexible board and piezo technology which opens up
a new class of reliable ready to use actuator and sensor modules. Tailored design and packaging are
seen as key factors for progress in custom applications. Load carrying structures with embedded
actuators, sensors and electronics, which are usually pre-integrated in modules, offer the
opportunity for noise reduction, vibration and shape control and health monitoring. The present
paper summarizes the potential of advanced, microsystems compatible piezotechnology for active
structures and systems. The focus will be given to PZT film and fibre processing and the integration
in silicon wafer, ceramic multilayer and polymer matrix architectures. Finally, forward-looking
applications are highlighted.
Damping by SMA in Civil Engineering Structures
Authors: Martorell F. , Torra Vicenç , Isalgué Antonio , Perea M.L. , Terriault Patrick , Lovey Francisco C.
Published: March 2009

The particular properties of Shape Memory Alloys associated to their thermoelastic
martensitic transformation with hysteresis permits applications of SMA as a damper via the
conversion of the work absorbed in each cycle in heat. The guaranteed behavior requires the
appropriateness of SMA for the complete requirements of the application. This work shows two
complementary aspects of the SMA application in Civil Engineering, the first of them, the SMA
dampers in earthquake damping of a family house. The second aspect relates an elementary
approach to the damping of stayed cables in bridges, using some data from the Iroise Bridge. The
application in the first case needs long time constancy of properties and then around 200 cycles
during an earthquake. In the second case, the fatigue life of SMA imposes that only small strains in
the alloy can be accepted. Finally, it is emphasized the importance of working conditions, including
temperature and time.
Inhibition of Alzheimer Amyloid Aggregation with Sulfate Glycopolymers
Authors: Miura Yoshiko , Yamamoto Kiyofumi , Yasuda Kikuko , Nishida Yoshihiro , Kobayashi Kazukiyo
Published: March 2009

Glycopolymers carrying sulfate saccharides were found to suppress the formation of
amyloid fibrils by amyloid beta peptides, as evaluated by fluorescence assay of thioflavin T and AFM.
CD spectra showed that the conformation of amyloid beta peptides was changed from beta peptides
depended on the glycopolymer additives, and that the glycopolymer additives reduced the β-sheet
contents. Neutralization activity was confirmed by in vitro assay with HeLa cells. The sulfate group
and the appropriate sugar contents were essential for the inhibitory effect.
Towards an Integrated, Fully-Implantable Vestibular Prosthesis for Balance Restoration
Authors: Constandinou Timothy G. , Georgiou Julius , Toumazou Chris
Published: March 2009

Neuroprosthetics is a relatively new topic but it has already shown its potential. Since the
application of this science, it has already significantly improved the quality of life of over 60,000
individuals who previously suffered from severely impaired hearing or total deafness. Today,
through use of cochlear implants, children born totally deaf can enjoy going to regular schools and
communicating normally. Individuals suffering from dizziness and balance disorders can also
benefit from the progress made in cochlear prosthetics. The inner ear's vestibular system provides
cues about self-motion and help stabilise vision during movement. Damage to this system can result
in dizziness, imbalance, blurred vision and instability in locomotion, a leading cause of death in the
elderly. We propose a hybrid CMOS/MEMS platform for bypassing a dysfunctional pathway in
individuals that suffer from balance-related disorders. Combining MEMS-based inertia sensing
with CMOS-based neural monitoring and processing electronics, this prosthesis aims to deliver a
corrective artificial stimulus to the vestibulocochlear (VIII) nerve. We describe a novel system
outlining the architectural aspects and implementation methodology used in the design.
Theory and Experiments for Mechanically-Induced Remodeling of Tissue Engineered Blood Vessels
Authors: Gleason Rudolph L. , Wan William
Published: March 2009

There is a great unmet clinical need to develop small diameter tissue engineered blood
vessels (TEBV) with low thrombogenicity and immune response and suitable mechanical
properties. In this paper we describe experimental and computational frameworks to characterize
the use of mechanical stimuli to improve the mechanical properties of TEBVs. We model the
TEBV as a constrained mixture and track the production, degradation, mechanical state, and
organization of each structural constituent. Specifically, we assume that individual load bearing
constituents can co-exist within each neighborhood and, although they are constrained to deform
together, each constituent within this neighborhood may have different natural (i.e., stress-free)
configurations. Motivated by this theoretical framework, we have designed a bioreactor and
biomechanical testing device for TEBVs. This device is designed to provide precise and
independent control of mean and cyclic luminal flow rate, transmural pressure, and axial load over
weeks and months in culture and perform intermittent biaxial biomechanical tests. This device also
fits under a two-photon laser scanning microscope for 3-dimenstional imaging of the content and
organization of cells and matrix constituents. These data directly support our theoretical model.
Design of a Progressively Expandable Stent Using Finite Elements
Authors: Terriault Patrick , Lafortune P. , Plamondon Dominic , Brailovski Vladimir
Published: March 2009

Currently, a minimally invasive surgery called stenting is extensively used to increase the
lumen of partially obstructed arteries. Unfortunately, restenosis, a postoperative phenomenon in
which the lumen of the artery is reduced due to a traumatism of the artery, is still a concern. The
most popular solution that has been adopted by stent manufacturers comprises drug-eluting stents.
This paper presents a new stent concept in which the treatment of restenosis is carried out from a
completely different angle. Indeed, instead of traumatizing the artery, and then trying to control
restenosis with drugs, the new stent minimizes the traumatism of the artery by expanding itself, not
instantaneously, but progressively, and in a controlled manner. To achieve this, a nitinol stent over
which a series of polymer rings are installed tries to reach a fully deployed configuration, but the
polymer rings, which act as a retainer, become soft over time due to creeping. Thus, after the initial
deployment in the artery, the stent continues its expansion autonomously over an extended period
of time (a few weeks). It is believed that the artery has enough time to adapt to the expansion,
leading to minimum traumatism. This paper presents the stent design.
Functional Materials for Wearable Sensing, Actuating and Energy Harvesting
Authors: De Rossi Danilo , Carpi Federico , Galantini Fabia
Published: March 2009

This paper describes the early conception and latest developments of electroactive polymer (EAP)-
based sensors, actuators and power sources, implemented as wearable devices for smart electronic
textiles (e-textiles). Such textiles, functioning as multifunctional wearable human interfaces, are
today considered relevant promoters of progress and useful tools in several biomedical field, such
as biomonitoring, rehabilitation and telemedicine. This paper presents the more performing EAPbased
devices developed by our lab and other research groups for sensing, actuating and energy
harvesting, with reference to their already demonstrated or potential applicability to electronic
textiles.
Ultrasonic Transducer Based on β-PVDF for Fluidic Microagitation in a Lab-on-a-Chip Device
Authors: Cardoso Vanessa F. , Martins P. , Serrado-Nunes Jivago , Rebouta L. , Rocha José Gerardo , Minas G. , Lanceros-Méndez Senentxu
Published: March 2009

This paper describes a fully-integrated lab-on-a-chip device for testing and monitoring
biochemical parameters in biological fluids. The major innovation of this microdevice is the
application of an acoustic microagitation technique with automatic electronic control based on a
β-PVDF piezoelectric polymer placed underneath the microfluidic structures. Experimental results
regarding the influence of the thickness of the polymer on the reaction rate of biological fluids are
presented. Moreover, the study of the transmittance curve of β-PVDF with transparent conductive
electrodes is also presented. Transparent electrodes are a constraint once the polymer is incorporate
underneath the reaction chamber due to the analytical measurement by spectrophotometry.
Towards In Vivo Nanomachines
Authors: Friedrichs Eike , Jungmann Ralf , Tsokou Angeliki , Renner Stephan , Simmel Friedrich C.
Published: March 2009

DNA has been recently used to construct a variety of nanoscale machines and switches,
among them devices which can translocate, compute, or bind and release molecules. For future
applications it is interesting to investigate whether these "artificial" functions can also be
implemented in vivo. As one step towards in vivo applications, we currently utilize RNA molecules
for construction or control of molecular devices. RNA molecules can be transcribed from "artificial
genes" and either fold into functional nanoassemblies themselves or drive other nucleic acid-based
devices as a "fuel". Furthermore, coupling of nanomachines to RNA transcription enables control of
their behavior using gene regulatory motifs.
Cyborg MAVs Using Power Harvesting and Behavioral Control Schemes
Authors: Reissman Timothy , Garcia Ephrahim
Published: March 2009

The focus of this research is to use flying insects, coupled with lightweight electronics,
to develop cyborg MAVs, or CMAVs. The premise isn't simply to build telemetry devices on the
insects, but to embed controls and power systems within the insects to create MAVs that are alive
yet manipulated in their actions. The model insect implemented is the Manduca sexta moth, which
has a wingspan up to 10cm, a body mass up to 2 grams, and can withstand payloads up to 1 gram.
The technique used to create these CMAVs is an integration of MEMS and CMOS devices onto a
single silicon device that is surgically inserted into the moth. The control and sensor systems are
powered by harvesting energy from the vibration of the insect flight by means of piezoelectric
material and inductor-coils. Methods for controlling the insect flight include reactionary responses
to visual and direct stimulation. Guidance is achieved through an ultra-wideband communication
system and a micro GPS system. The primary discussion topics of this paper are the power
harvesting devices employed and the control schemes used to manipulate the flight of the CMAVs.
Reverse Engineering of Self-Propelled Anguilliform Swimmers
Authors: Kern Stefan , Chatelain Philippe , Koumoutsakos Petros
Published: March 2009

Biological mimesis pertains usually to the translation of a natural form or mechanism
into an engineering design. Mimesis however can also apply to the design process itself as one may
employ the principles of natural evolution to the optimization of engineering problems. As an
exemplary case study for this approach, we present the application of an Evolutionary Strategy to
the optimization of anguilliform swimming. This investigation uses three-dimensional simulations
of the flow past a self-propelled body. The motion of the body is not specified a priori but is instead
the result of a reverse engineering process. This procedure helps us identify systematically the links
between swimming kinematics and biological function. Three distinct objectives are considered:
the swimming efficiency, the burst swimming speed, and the acoutic far field signature. We focus
on the acoustic and dynamic features, and in particular, we extract phaseshift information for
motion controllers..
Modeling the Dynamics of Human Swimming
Authors: Nakashima Motomu
Published: March 2009

Swimming movement of human being is quite distinctive compared to those of the other
aquatic animals. Taking into account of such peculiarity, the authors recently have developed a
simulation model “SWUM” to analyze the dynamics of the human swimming. The simulation model
itself is firstly described. Next, examples of analysis, applications of the model, and its future are
respectively described.
Vortex Rings in Bio-Inspired and Biological Jet Propulsion
Authors: Krueger Paul S. , Moslemi Ali A. , Nichols J. Tyler , Bartol Ian K. , Stewart William J.
Published: March 2009

Pulsed-jets are commonly used for aquatic propulsion, such as squid and jellyfish
locomotion. The sudden ejection of a jet with each pulse engenders the formation of a vortex ring
through the roll-up of the jet shear layer. If the pulse is too long, the vortex ring will stop forming
and the remainder of the pulse is ejected as a trailing jet. Recent results from mechanical pulsedjets
have demonstrated that vortex rings lead to thrust augmentation through the acceleration of
additional ambient fluid. This benefit is most pronounced for short pulses without trailing jets.
Simulating vehicle motion by introducing background co-flow surrounding the jet has shown that
vortex ring formation can be interrupted, but only if the co-flow is sufficiently fast. Recent in situ
measurements on squid have captured vortical flows similar to those observed in the laboratory,
suggesting thrust augmentation may play a role in their swimming performance. Likewise, recent
measurements with a mechanical self-propelled pulsed-jet vehicle (“robosquid”) have shown a
cruise-speed advantage obtained by pulsing.
Fractals to Model Hierarchical Biomaterials
Authors: Carpinteri Alberto , Cornetti Pietro , Pugno Nicola Maria , Sapora Alberto
Published: March 2009

Many biological materials exhibit a hierarchical structure over more than one length
scale. Understanding how hierarchy affects their mechanical properties emerges as a primary
concern, since it can guide the synthesis of new materials to be tailored for specific applications. In
this paper the strength and stiffness of hierarchical materials are investigated by means of a fractal
approach. A new model is proposed, based both on geometric and material considerations and
involving simple recursive formulas.
Dynamic and Static Displacements of Atoms in B2-Phase of TiNi Alloy
Authors: Gundyrev Vyacheslav M. , Zel'dovich Vitaly I.
Published: March 2009

We measured integrated intensities of 26 reflections of the B2-phase of titanium
nickelide single crystal and determined structure factors for these reflections. Based on the structure
factors, mean squares of displacements of Ni and Ti atoms with respect to the crystal-lattice sites
have been determined. After that we determined the mean squares of atomic displacements Ni
and Ti in temperature range of existence of the B2-pase, at temperatures Т1=328 K and T2=376
K. We separated the mean squares of atomic displacements Ni and Ti into static and
dynamic ones. The mean squares of dynamic displacements of Ni and Ti atoms are identical, but the
mean square of static displacements is greater by a factor of 4.7 for Ni atoms than for Ti atoms. The
Debye temperature calculated from the mean squares of displacements of Ni atoms is 360 K; that
calculated for Ti atoms in a similar way is 390 K. The large value of complete atomic displacements
in TiNi is due to static rather than dynamic displacements of atoms, mainly due to static
displacements of nickel atoms.
Experimental Characterization of NiTi SMAs Thermomechanical Behaviour Using Temperature and Strain Full-Field Measurements
Authors: Schlosser Pauline , Favier Denis , Louche Herve , Orgéas Laurent
Published: March 2009

The tension behaviour of initially austenitic NiTi thin wall tubes was investigated using
measurements of temperature and strain fields simultaneously. The first specimen was totally
superelastic but the unloading was performed before the end of the loading stress plateau. The
second specimen loading was performed beyond the stress plateau to allow analyzing the
unloading, but was not superelastic and at a faster strain rate. Both tests show homogeneous
behaviour at the beginning of the loading. Strong localisations, taking the shape of helical bands,
are observed during the loading and unloading stress plateaus. To obtain quantitative energy
information, allowing a better recognition of the deformation mechanisms, an estimation of the
local heat sources based on image processing of the temperature fields is presented. Two methods
of heat sources estimation allowing analysis of deformation mechanisms are proposed in the present
paper: first during the homogeneous, then during localized stages.
SMA Fatigue in Civil Engineering Applications
Authors: Casciati Fabio , Faravelli Lucia , Isalgué Antonio , Martorell F. , Soul H. , Torra Vicenç
Published: March 2009

Shape Memory Alloys (SMA) show particular properties associated to their martensitic
transformation between metastable phases. Their use in dampers requires a deep knowledge of the
SMA behavior and its coherence with the application requirements. In earthquakes engineering
standard conditions require that, after several years or decades at rest, an excellent performance is
necessary for one or two minutes, i.e., nearly 200 working oscillations. When the target is the
damping of stayed cables in bridges under the wind or rain actions, a larger number of oscillations
is expected per each working day. This contribution analyzes the fatigue behavior of a CuAlBe
alloy (appropriate for earthquakes) and discusses the results of some available experiments on a
NiTi alloy for their eventual application to stayed cables..
High Energy Milling and Hot Extrusion of Equiatomic NiTi Shape Memory Alloy
Authors: Silva Maria do Carmo , da Silva L.C.E. , Ambrozio Filho Francisco
Published: March 2009

In this work a 50Ni50Ti at % powder mixture, commercially pure, prepared by
mechanical alloying in an attritor with the following conditions: the milling speed and the ball
charge were 1500 rpm and 15:1 respectively. The milling time was 1h under a nitrogen atmosphere
at room temperature. After milling it was determined the particles size distribution, the phases by Xray
diffractions (XRD) and the powder morphology by scanning electron microscopy (SEM). The
powders after milling were compacted and hot extruded at 600 °C with an extrusion ratio of 3 to 1
and characterized by evaluation the density and microstructural determination by optical
microscopy. The obtained results are discussed to show that this route could be an alternative route
to prepare the shape memory alloy.
Influence of Substrate Temperature on Texture for Deposited TiNi Films
Authors: Ikenaga Noriaki , Kishi Yoichi , Yajima Zenjiro , Sakudo Noriyuki
Published: March 2009

In order to fabricate two-dimensional micro actuators with shape memory alloy films, it is
especially important to evaluate the anisotropy of transformation strain that is caused by texture. In
this paper, microstructures of sputter-deposited TiNi films are examined. The films of 1 μm in
thickness are sputter-deposited on Si(001) substrates by RF magnetron multi-sputtering system
equipped with four separate confocal sources as well as with substrate heating. Pure Ti and Ni targets
of 50 mm in diameter are used for the sources. The films deposited at ambient temperature have been
generally amorphous. However, we find that some films which are deposited at 773K of substrate
temperature are crystalline, when we appropriately choose sputtering parameters such as source
voltage and the distance between a target and the substrate. X-ray powder diffraction and pole figure
measurements reveal that these films are oriented with {110}B2 parallel or inclined at 45 degree to
the substrate. Furthermore, we also find that crystallized film is deposited even at 673K of substrate
temperature by applying pulse bias voltage to the substrate.
Thermomechanical Modelling and Experimental Testing of a Shape Memory Alloy Hybrid Composite Plate
Authors: Daghia Federica , Faiella Gabriella , Antonucci Vincenza , Giordano Michele
Published: March 2009

Shape memory alloys (SMA) exhibit functional properties associated with the shape
memory effect, responsible of the SMA shape recovery after a cycle of deforming-heating and of a
simultaneous generation of mechanical work. Composite systems incorporating SMA wires have
the ability to actively change shape and other structural characteristics. The functional properties of
such adaptive composites are related to the martensitic transformation in the SMA elements and to
the constraining behaviour that the composite matrix has on the SMA wires. In this work the
behaviour of a shape memory alloy hybrid composite (SMAHC) is numerically and experimentally
investigated. A plate was fabricated using prestrained SMA wires embedded in an epoxy resin pre
preg glass fibres composite system. Upon calorimetric and mechanical material characterization, a
finite element model was used in order to predict the structural behaviour of the SMAHC. In the
experimental tests, the plate was clamped at one side and actuated via electrical heating.
Temperature and displacement data were collected and compared with the prediction of the finite
element model. The results show that the model is able to capture the shape change in the actuation
region, although a thorough description of the SMAHC behaviour requires further modelling work,
including the simulation of the SMA loading history during composite manufacturing.
Effect of the Loading History on Shape Memory Alloy Transformation Temperatures
Authors: Faiella Gabriella , Antonucci Vincenza , Giordano Michele , Daghia Federica , Viola Erasmo
Published: March 2009

Due to the complex microstructure and phase transformations taking place in Shape
Memory Alloys (SMA), the behaviour and properties of these materials are deeply influenced by
their loading history in terms of stress, strain and temperature. Indeed, a thorough understanding of
the effects of the loading history on SMA properties is fundamental for a correct modelling and
design of SMA applications, in particular in the case of complex loading. An example are shape
memory alloys embedded in composite systems, in which stress, strain and temperature vary
simultaneously depending upon the properties of the SMA and composite. This work presents the
first results of an experimental investigation on the effects of the loading history on SMA
transformation temperatures. Nitinol wires of untrained material were considered. Specimens
consisting of Martensite and R-phase were subjected to different loading histories, keeping in turn
stress, strain or temperature at a constant value. Transformation temperatures at zero stress of these
samples were measured via Differential Scanning Calorimetry. Contrarily to most constitutive
models assumptions, the DSC results highlight a dependence of the transformation temperatures on
the loading history, influencing in particular the Martensite to Austenite phase transformation.
Elemental Interfaces and Displacive Phase Transformations
Authors: Paidar Václav
Published: March 2009

Two basic processes, namely shear and shuffling of atomic planes can be considered as
elementary mechanisms of displacive phase transformations. The atomistic models suitable to
investigate the role of interfaces in the structural changes are tested. The many-body potentials are
used for the description of interatomic forces. General displacements of atomic planes are
examined, i.e. γ-surface type calculations extensively used for stacking fault and lattice dislocation
analysis are applied to single plane shuffling and alternate shuffling of every other atomic plane
producing in combination with homogeneous deformation the hcp structure. Similar approach
considering shear type planar displacements leads to the Zener path between the bcc and fcc
lattices. The effect of additional deformation required to obtain the close-packed atomic
arrangements is analysed.
Influence of Thermomechanical Treatment on Transformation Temperatures of Cu-Al-Ni Shape Memory Alloys
Authors: Veloso Ana Cris R. , Gomes Rodinei Medeiros , Santos Dagoberto Brandao , Lima I.C.E.G. , de Lima Severino Jackson Guedes , Melo Tadeu Antonio de Azevedo
Published: March 2009

In this study Cu-13.8Al alloys with 3.0% and 4.0% (wt%) of nickel were obtained by
induction melting. The effect of homogenization heat treatment and hot rolling on the
transformation temperatures of these alloys was investigated by differential scanning calorimetry. It
was observed that the transformation temperatures increase with long homogenization times, and
also by hot rolling, and this displacement is smaller for alloys with 4.0% of nickel. In both alloys in
the quenched state, the reversion reaction is characterized by the appearance of multiple peaks
attributed to the presence of martensites 2H and 18R. The influence of the rolling process must be
associated with the loss of Ni and Al during the process.
The Investigation about the Shape Memory Behavior of Wool
Authors: Hu Jin Lian , Dong Zheng E , Liu Yan , Liu Yi Jun
Published: March 2009

Shape memory polymers are a promising class of stimuli-responsive materials that
have dual-shape capability. This kind of materials can recover their shape in a
predefined way from temporary shape to desired permanent shape when exposed to an
appropriate stimulus. In the development and extensive application of synthetic shape
memory polymers on textile industrials, the thermal and hygrothermal effects of wool
materials have attracted considerable attention. In this article the fundamental concept
of the shape memory polymers and the fundamental aspects of the shape-memory
effect were reviewed. The thermal and hygrothermal effects of wool materials were
also summarized to discuss the shape memory behavior of wool materials. Besides the
effects of synthetic shape memory polymers on the thermal and hygrothermal of the
woven wool fabrics were introduced to show the shape memory behavior of treated
wool further.
Photochromic Wool Fabrics with Enhanced Durability and Photochromic Performance
Authors: Lin Tong , Cheng Tong , Brady Rex , Wang Xun Gai
Published: March 2009

In our previous work, we have produced a photochromic wool fabric by applying a thin
layer of hybrid silica-photochromic dye onto the wool surface. The coating showed a very fast
optical response, but had little influence on the fabric handle, however durability was low. In this
context, we reported that durability of the hybrid layer can be improved by introducing epoxy
groups into the silica matrix via co-hydrolysis and co-condensation of an alkyl trialkoxysilane
(ATAS) and 3-glycidoxypropyltrimethoxysilane (GPTMS). The presence of epoxy groups in the
silica enhanced both washing and abrasion durabilities. Also, the optical response speed was
slightly increased as well. Effects of the type of alkyl silane and the GPTMS:alkyl silane ratio on
the coating durability, fabric handle and optical response were examined.
Designing with a Responsive Colour Palette: The Development of Colour and Pattern Changing Products
Authors: Robertson Sara , Taylor Sarah , Christie Robert , Fletcher John , Rossini Luca
Published: March 2009

This paper presents an illustrated discussion of the potential for creative design applications of
thermochromic textiles brought into contact with specifically designed heat-profiling circuitry. The
results are derived from a current research programme at the design/technology interface on the
application of colour change technology in interior textile design. Examples are given of textile
samples combining printed thermochromics with circuitry to demonstrate the aesthetic qualities that
can be achieved from integration of the technologies in a flexible fabric system. Dynamic colour
change effects controlled by prototype circuitry and power electronics are demonstrated. The paper
concludes with an analysis of the potential for product/artefact development in the area of “smart”
design and how, as a consequence, a responsive interior might be envisaged.
Gold Coated Polyester Yarn
Authors: Schwarz Anne , Hakuzimana Jean , Gasana Emmanuel , Westbroek Philippe , Van Langenhove Lieva
Published: March 2009

Textiles are increasingly studied to use them as sensing and measuring devices of body
parameters. For this purpose they need to be modified to provide on the one hand reliable and stable
electroconductive properties and on the other they should be biocompatible. This can be achieved by
depositing electroconductive materials such as metals on the textile surface. Gold is an ideal material to
use as it offers the aforementioned criteria and can be applied as a thin coating on the surface of a fibre,
yarn or fabric. We developed gold coated yarns that are highly electrically conductive, skin-friendly
and stable.
In this presentation, we describe the gold coating method and show first results of the characterisation
of the coated yarns.
A commercially available polyester yarn was coated with a thin layer of gold by using an electroless
plating method. The plating solution was optimised towards the concentration of each component, the
working temperature and pH.
The quantitative analysis of the surface coverage of gold with EDAX and cyclic voltammetry showed
in both cases a surface coverage of more than 95%.
For the future, research will be continued to characterise the longterm behaviour of the yarns.
Electrically Conductive Monofilaments for Smart Textiles
Authors: Jiménez Laura , Rocha A.M. , Aranberri I. , Covas José A. , Catarino A.P.
Published: March 2009

The main objective of this work is to develop conductive yarns to be used as electrical
wiring in e-textiles with the typical mechanical properties of a textile yarn. Present work
deals with the study of conductive polymer composites filaments of PP (polypropylene)
with CB (carbon black), carbon black of high conductivity (CBHC) and CF (carbon
fibers) .The novelty of this work resides in creating oriented filaments using traditional
fiber processing techniques together with a specially designed drafting machine. In the
authors’ opinion, the composite conductivity could be improved with the orientation of
the (nano)carbon-based fillers by melt drawing after extrusion in order to facilitate the
flow channels creation.
Monte Carlo Simulation of Electroactive Polymer Actuators
Authors: Kiyohara Kenji , Sugino Takushi , Asaka Kinji
Published: March 2009

In order to understand the mechanism of the bending motion of the electroactive polymer
actuators from the molecular interaction, we performed Monte Carlo simulations in two length scales;
the micrometer scale and the nanometer scale. In the micrometer scale picture, the bending motion of
an actuator can be viewed as the inhomogeneous expansion/contraction of the three layer system. We
theoretically formulated the deformation of the actuator in terms of the elastic constants and the stress
exerted due to the applied voltage. For the nanometer scale, noting that the electrodes of the EAP
actuators have porous structures, we modeled the anode and the cathode by the porous electrodes
where the ions are confined in the space with the dimension comparable to the ion size. We found
that significant osmotic stress arises in the porous electrodes when voltage is applied. The results of
such multi-scale analyses are combined with the experimental results to obtain the insights into the
molecular mechanism of the actuators and to give the guideline for the molecular design of the
actuators.
Tunable Membrane for Electromagnetic Devices Using Dielectric Elastomers
Authors: Bolzmacher Christian , Bauer Karin , Schmid Ulrich , Seidel Helmut , Hafez Moustapha
Published: March 2009

The amplitudes of miniaturized electromagnetic actuators are clearly enhanced if the
eigenfrequencies of the membrane are used for actuation. However, the bandwidth for such
operation is very limited. This can be overcome to some extent by the employment of membranes
with electrically tunable stiffness. In this context we investigated membranes of dielectric elastomer
materials and present experimental results on the ability to change their pre-strain to shift the
eigenmodes to lower frequencies upon activation. Furthermore, the viscoelastic properties of an
acrylic and a silicone membrane are investigated and compared to dynamic experiments. The
parameters for the stiffness and viscoelasticity are derived from the experimental creep data and
incorporated in a hyperelastic material model. Using this adapted stress-strain relationship the
membrane behavior over time can be evaluated for different loading as well as pre-strain
conditions.
Distributed Impedance Model of Ionic Polymer-Metal Composite Actuators
Authors: Takagi Kentaro , Asaka Kinji , Nishida Gou , Nakabo Yoshihiro , Luo Zhi Wei
Published: March 2009

This paper discusses a distributed system modeling of the electrical impedance of ionic
polymer-metal composites from the point of view of the electrode roughness. A diffusion-like
equation is derived from the distributed circuit model which represents the fractal-like distribution of
the polymer-electrode interface. The port-Hamiltonian representation of the system is also shown. In
the experiment, the frequency response of the impedance is measured under various conditions.
Ionic Polymer-Metal Composite Actuator Behaviour in Two Novel Configurations
Authors: Khazravi M. , Dehghani-Sanij A.A.
Published: March 2009

IPMCs are one of the most promising smart actuators to replace traditional actuators for some specific
applications particularly in the micro-nano scales. IPMC actuator’s shape and configuration have a dramatic
effect on the actuation parameters. While the behaviour of IPMCs as a single fixed end strip actuator
(cantilever) has been widely studied since the early 80’s, its behaviour in other configurations is relatively
unknown. This paper presents work carried out in order to reconfigure these actuators for some new
applications. The first configuration is when both ends of an IPMC actuator strip are fully constrained, in
both the actuator plane and the normal direction. In this case the displacement and force measurements at the
mid point of the strip are presented. The results of a series of experiments show the behaviour of the actuator
in this configuration and using these results some models have been proposed. The second configuration is
when only one end of the strip is fixed and the other end is constrained in the normal direction with respect
to the plane of the actuator strip. A series of experiments were also carried out to explore the IPMC actuator
behaviour in terms of maximum displacement and force generated in this configuration. The behaviour of the
IPMC actuator in these two configurations is also investigated by studying the internal stresses in the IPMC
structure.
Contractile and Buckling Actuators Based on Dielectric Elastomers: Devices and Applications
Authors: Carpi Federico , Frediani Gabriele , Mannini Andrea , De Rossi Danilo
Published: March 2009

Dielectric elastomer (DE) actuators are able to typically show significant
electromechanical performances, which make this electroactive polymer technology particularly
attractive for so-called ‘artificial muscle’ devices. This paper deals with two types of DE actuators
recently developed in our lab. The first type is represented by the so-called ‘folded actuators’, based
on a simple configuration suitable to easily implement linear contractile devices. The structure
consists of a monolithic electroded sheet of elastomer, which is folded up and compacted; the
resulting contractile actuator is functionally equivalent to a multilayer stack with interdigitated
electrodes, but can be manufactured more easily. The second type of devices is represented by the
so-called ‘buckling actuators’. They operate with out-of-plane unidirectional displacements of an
elastomer membrane. This paper describes the structure and the properties of both these actuators,
along with different examples of applications currently being developed in our lab for the
biomedical, the robotic and the space fields.
A Co-Axial Dielectric Elastomer Actuator
Authors: Stoyanov Hristiyan , Kofod Guggi , Gerhard Reimund
Published: March 2009

Dielectric elastomer actuators based on Maxwell-stress induced deformation, are considered for
many potential applications where high actuation strain and high energy density are required. They
usually rely on a planar actuator configuration, however, a string-like actuator would be less bulky,
and more versatile for several applications. In this paper, a co-axial dielectric elastomer actuator that
produces relatively high actuation strain is presented. The actuator is manufactured through
alternating dip-coating steps with insulating and conductive thin layers. A soluble thermoplastic
block-copolymer, SEBS(poly-(styrene-ethylene-butylene-styrene), is used for the dielectric layers
as well as for the host material of the compliant electrodes. Electrical conductivity of the electrodes
is achieved by incorporation of conductive carbon-black particles in the elastomer matrix. Actuators
with a single and with multiple active layers (up to three) have been successfully demonstrated. This
geometry is advantageous in that it is compact and can be bundled easily, and should therefore be
practical in applications such as “artificial muscles”.
A Closer Look at the Polyacrylamide Fibers for Natural-Like Artificial Muscle Fabrication
Authors: Bassil Maria , Davenas Joel , El Tahchi M.
Published: March 2009

Polyacrylamide (PAAM) gels suits better the artificial muscle fabrication despite their
response time which stays low compared to natural human muscle. This main problem is due to
their bulky form where the ions exchange takes a long time compared to the microsecond scale in
human muscle. Thus a successful artificial muscle will need to replicate the small scales of the
muscle fibers that can achieve fast response. In this study we develop a technique for PAAM gel
fibers fabrication with micrometric diameter, 1D structure, aiming to convert isotropic swelling into
a directional one and we propose an electrical activation mode for a linear actuation mechanism.
The Characterization of Defects in Silicon Carbide Crystals by X-Ray Topography in the Back-Reflection Geometry
Authors: Vetter William M.
Published: March 2009

Synchrotron white-beam x-ray topographs taken in the back-reflection mode have proved a powerful tool in the study of defects in semiconductor-grade silicon carbide crystals. Capable of mapping the distribution of axial dislocations across a wafer's area (notably the devastating micropipe defect), it can also provide information on their natures. Under favorable conditions, various other types of defect may be observed in back-reflection topographs of SiC, among which are subgrain boundaries, inclusions, and basal plane dislocations. Observed defect images in backreflection topographs may be simulated using relatively simple computer algorithms based on ray tracing. It has been possible to use back-reflection topographs of SiC substrates with device structures deposited upon them to relate the incidence of defects to device failure.
Investigation and Identification of Transition Metals in p-Type Boron-Doped Silicon by Non-Invasive Techniques
Authors: Palais Olivier , Hidalgo P.
Published: March 2009

This paper describes the “pairing - dissociation” behaviour of metal-acceptor pairs and proposes a method to measure metal concentrations in p-type boron doped silicon based on a contactless measurement technique. The first part of this paper sums up the previous non destructive electrical characterization methods that have led to the evaluation of iron concentrations in p-type boron- doped silicon by the inspired contactless techniques. It is demonstrated that the lifetime measurement method proposed allows the detection of contaminants at concentrations as low as 109at.cm-3. In the second part, the specific cases of iron and chromium that are among the most harmful metal contaminants are discussed. We show that these contaminants, even if their concentrations are not known, are identifiable by contactless measurements that allow the analysis of their kinetics of pairing with boron atoms and of their respective interactions with extended defects, such as grain boundaries in multicrystalline silicon.
Defect Engineering in Impurity-Free Disordered (Al)GaAs for Optoelectronic Devices Application
Authors: Deenapanray Prakash N.K.
Published: March 2009

The defects created in GaAs and AlxGa1-xAs epitaxial layers by impurity-free disordering (IFD) were studied by deep level transient spectroscopy (DLTS) and capacitance-voltage (C-V)measurements. IFD introduces three electron traps S1 (EC – 0.23 eV), S2* (EC – 0.53 eV), and S4 (EC – 0.74 eV) in n-type GaAs. We propose that S1 is a defect that may involve As-clustering or a complex of arsenic interstitials, Asi, and the arsenic-antisite, AsGa. S2* is the superposition of two defects, which may be VGa-related, while S4 is identified as the defect EL2. The same set of defects is created in impurity-free disordered n-type AlxGa1-xAs, but with the defects either pinned relative to the conduction band or the Fermi level. In contrast to disordering in n-type GaAs, IFD of p-type GaAs results in the pronounced atomic relocation of impurities, including Zn and Cu, in the nearsurface region of the disordered layer. The redistribution of these fast diffusers poses serious constraints regarding the application of IFD to the band gap engineering of doped GaAs-based heterostructures for optoelectronic devices application. However, we will demonstrate that this impurity segregation effect can be minimized. The discussion takes a critical look at the technological viability of impurity-free disordering for the integration of GaAs-based optoelectronic devices.
First Principles Calculations of Hydrogen Aggregation in Silicon
Authors: Martsinovich N. , Rosa A.L. , Heggie M.I. , Briddon Patrick R.
Published: March 2009

We use DFT calculations to investigate the problem of hydrogen aggregation in silicon. We study atomic structures of finite hydrogen aggregates containing four or more hydrogen atoms. Beyond four hydrogen atoms, complexes consisting of Si-H bonds are likely to form, rather than aggregates of H2 molecules, which are the most stable diatomic hydrogen complex. Our calculations show that the basic structural unit of such complexes is a hydrogenated dislocation loop, which is formed spontaneously by a structural transformation of two H∗2 complexes. Hydrogen-induced formation of dislocation loops may account for the experimental observations of dislocation loops in proton-implanted or hydrogen plasma-treated silicon. We indicate the routes leading from H∗2 aggregates and hydrogenated dislocation loops to twodimensional hydrogen-induced platelets. We discuss the effect of hydrogen-catalysed formation of dislocation loops on the plasticity of silicon.