bluuebunny/crossref_metadata_2025 huggingface dataset:
Piezoelectric Coefficients of Thin Polymer Films Measured by Interferometry
Authors: Zheng Zhenji , Guya Ian L. , Tansley Trevor L.
Published: August 2009

The effective d33 of sub-micron piezoelectric polymer films, deposited on glass substrates, has been measured using an optical interferometer. The polymers used were polyvinylidene fluoride (PVDF) and copolymers of PVDF with trifluoroethylene (TrFE). The interferometer measures movement of the polymer surface in response to an applied electric field, and is easily able to detect motion of a picometre. In this situation, the rigid glass substrate effectively clamps the soft polymer film in the lateral direction. Nevertheless, effective d33 values approaching 10 pm Vhave been observed.

One advantage of such thin films, is the ability to pole them with quite low voltages. For example, a 100 nm film can be poled by 10 volts. The low voltage required to achieve poling in such thin films means that the poling voltage can be left permanently connected, thus maintaining the piezoelectric activity. By adding a periodic bias voltage to the driving signal, it is possible to observe hysteresis in the piezoelectric coefficient corresponding to the polarization hysteresis loop. The piezoelectric coefficient shows an abrupt change in sign at the coercive field. corresponding to the reversal of the net polarization.
Design of Microelectrode Arrays for Electrostatic Microactuators and Capacitive Microsensors
Authors: Chang Peizen , Chang Chienliu , Yen Kaihsiang
Published: August 2009

This study presents a novel means of simplifying the design process of micro machined deformable mirrors. Varying the widths of an array of constant-pitched electrodes allows us to precisely control the electrostatic-force profile needed to shape the mirror using only one voltage input. A mirror is formed by a thin membrane micromachined from a silicon wafer and is coated with a thin metallic film. The electrodes are deposited on a ground plane over which the membrane is suspended. By viewing the mirror as a surface composed of many small patches with the same pitch, the required traction of each patch can be calculated from the desired deformation by using basic elasticity formulae. The analytical solution of the electrostatic field between the mirror and an electrode of one pitch can be obtained by adopting the conformal mapping method. Once establishing the relationship between the traction and the width of the electrode, the widths of all the electrodes can be obtained by correlating the electrode width to that of the design goal. The proposed method applies equally well to design both membrane electrostatic actuators and capacitive sensors. Moreover, the design method is not necessary to solve the PDE (Partial Differential Equations) of the structure governing equations, and is always valid for any axisymmetric deformation.
Natural Frequencies of Multi-Layer Composite Plate with Embedded Shape Memory Alloy Wires
Authors: Ostachowicz W. , Krawczuk M. , Zak A.
Published: August 2009

This paper illustrates stress-strain relationships for a single composite lamina with SMA wires and shows their influence upon changes in natural frequencies of a composite multilayered plate. Governing equations based on the finite element method are presented. The plate is modeled by plate finite elements with eight nodes and five degrees of freedom at each node (i.e., three axial displacements and two rotations). For both axial displacements and rotations biquadratic shape functions are used. Results of numerical calculations for different initial strains of SMA wires and their influence on natural frequencies of a composite laminated plate are presented.
Piezoelectric Boundary Element Crack Closure Calculation of 3D Strain Energy Release Rates
Authors: Hill Lisa R. , Farris Thomas N.
Published: August 2009

Piezoceramic materials are very brittle and susceptible to fracture, especially under the severe loading conditions which may occur in service as sensors and actuators in smart structures. The presence of these cracks alters the mechanical and electrical fields inside the body, which can cause failure from a catastrophic fracture event or the cumulative effects of cyclic fatigue. A three-dimensional boundary element program is developed to evaluate the effect of flaws on piezoelectric materials. The program is based on the linear governing equations of piezoelectricity and relies on a numerically evaluated Green's function for solution. Mode I fracture is examined, combining the linear boundary element solution with the modified crack closure integral to determine strain, rather than total, energy release rates since this is the appropriate predictor for crack growth in piezoelectric materials. Solutions for a two-dimensional slit crack and three-dimensional penny-shaped and elliptical cracks are presented. These solutions are developed using the insulated crack face electrical boundary condition. The boundary element method combined with modified crack closure is shown to accurately calculate strain energy release rates for linear piezoelectric fracture.
Two Variant Modeling of Shape Memory Materials: Unfolding a Phase Diagram Triple Point
Authors: Wu Xiaochuang , Pence Thomas J.
Published: August 2009

For shape memory materials, the combined effects of hysteresis and phase mixing are described in the absence of stress by the four transformation temperatures: Mf, Ms, As, Af. These temperatures can be viewed as the four-way splitting of a single transformation temperature that applies when both effects are absent. Treating the combined effect of hysteresis and phase mixing in the presence of stress have led to internal variable models in which transformation zones replace abrupt transition boundaries in traditional stress vs. temperature thermodynamic phase diagrams. We discuss how these descriptions emerge from a hysteresis and phase mixing mediated unfolding of an underlying phase diagram for a three species system involving austenite and two variants of martensite. The unfolding concept dictates certain general features of the resulting phase diagram zonal geometry, correlates this geometry with particular transformations and transformation combinations, and provides insight into the evolutionary kinetics that governs these transformations. A complete evolutionary model for arbitrary temperature and single stress component histories can be extracted from knowledge of the purely thermal behavior coupled with material data specification in terms of: transformation strain, austenite and martensite elastic moduli, transformation latent heat, and the start and finish stresses for martensite detwinning. The accompanying evolutionary kinetics is given an incremental formulation that captures shape memory and superelasticity, and also allows for the identification of attracting states associated with periodic stressing. The kinetics consistently permits an algebraic description of transformation progression for phase species undergoing depletion, but not for those phase species that are in flux or are increasing under multiple concurrent transformation. This latter result is established by an analysis of the path independent integrability of the evolution kinetics which serves to clarify the resulting description with respect to other models.
Transformation of Embedded Shape Memory Alloy Ribbons
Authors: Jonnalagadda K. D. , Sottos N. R. , Qidwai M. A. , Lagoudas D. C.
Published: August 2009

Shape memory alloy (SMA) wires can be embedded in a host material to alter the stiffness or modal response and provide vibration control. The interaction between the embedded SMA and the host material is critical to applications requiring transfer of loads or strain from the wire to the host. Although there has been a significant amount of research dedicated to characterizing and modeling the response of SMA alone, little research has focused on the transformation behavior of embedded SMAs. In the current work, photoelasticity was used to quantify the internal stresses induced by the actuation of a thin SMA ribbon in a polymer matrix. Through the use of a CCD camera and a frame grabber, photoelastic fringes were digitally recorded at discrete time increments. The stress contours were then analyzed quantitatively as a function of time. A numerical simulation of the embedded ribbon was also carried out using a coupled SMA constitutive model. The thermomechanical model accurately predicted the stress contours throughout the experiment.
Development of Mesoscale Actuator Device with Microinterlocking Mechanism
Authors: Chen Quanfang , Yao Da-Jeng , Kim Chang-Jin "CJ" , Carman Greg P.
Published: August 2009

A novel proof-of-concept prototype Mesoscale Actuator Device (MAD) is described in this paper. The MAD is similar to piezoelectric driven inchworm motors with the exception that mechanically interlocking microridges replace the traditional frictional clamping mechanisms. The interlocked microridges, microfabricated from single crystal silicon, are shown to support macroscopic loads with exact values dependent upon manufacturing processes. Tests conducted on the current design demonstrate that the interlocked microridges support 16 MPa in shear or that two sets of 3 x 5 mm locked chips support a 50 kgf. Operation of a prototype MAD device containing microridges is accomplished at relatively large frequencies using an open loop control signal. Synchronizing the locking and unlocking of the microridges with the elongating and contracting actuator requires a dedicated waveform in the voltage signal supplied and permitted large operational frequencies. The system was successfully operated from 0.2 Hz to 500 Hz corresponding to speeds from 2,um/s to 5 mm/s. The upper limit (500 Hz) was imposed by software limitations and not related to physical limitations of the current device.
A Nonlinear Optimal Control Method for Magnetostrictive Actuators
Authors: Smith Ralph C.
Published: August 2009

This paper addresses the development of a nonlinear optimal control methodology for magnetostrictive actuators. At moderate to high drive levels, the output from these actuators is highly nonlinear and contains significant magnetic and magnetomechanical hysteresis. These dynamics must be accommodated by models and control laws to utilize the full capabilities of the actuators. A characterization based upon ferromagnetic mean field theory provides a model which accurately quantifies both transient and steady state actuator dynamics under a variety of operating conditions. The control method consists of a linear perturbation feedback law used in combination with an optimal open loop nonlinear control. The nonlinear control incorporates the hysteresis and nonlinearities inherent in the transducer and can be computed offline. The feedback control is constructed through linearization of the perturbed system about the optimal system and is efficient for online implementation. As demonstrated through numerical examples, the combined hybrid control is robust and can be readily implemented in linear PDE-based structural models.
The Effect of Temperature Dependent Material Properties on the Response of Piezoelectric Composite Materials
Authors: Lee Ho-Jun , Saravanos Dimitris A.
Published: August 2009

Analytical formulations for thermopiezoelectric composite materials are extended to account for thermal effects arising from temperature dependent material properties. The updated mechanics also has the inherent capability to capture thermal effects which arise due to coefficient of thermal expansion mismatch and pyroelectric phenomena, providing a comprehensive thermal analysis capability. The thermal effects are represented at the material level through the thermopiezoelectric constitutive equations. These equations are incorporated into a layerwise laminate theory to provide a unified representation of the coupled mechanical, electrical, and thermal response of piezoelectric composite materials. Corresponding finite element equations are derived and implemented for beams and plates to model the active and sensory response of piezoelectric composite laminates. Applications demonstrate the significance of incorporating temperature dependent material properties on the response of piezoelectric composite beams and plates in both active and sensory configurations.
An Integrated Active-Parametric Control Approach for Active-Passive Hybrid Piezoelectric Network with Variable Resistance
Authors: Morgan Ronald A. , Wang K. W.
Published: August 2009

Previous studies have shown that piezoelectric materials can be used to provide passive damping by shunting them with an electrical network, such as a series RL circuit. This same configuration can also be used in conjunction with an active voltage source as an active-passive hybrid vibration control method. This active-passive piezoelectric network (APPN) concept, which combines the advantages of passive damping and active control, has proven to be very effective for vibration suppression, especially in narrow-band applications. It has also been recognized that the resistor element in these devices, which is necessary to provide passive damping, can reduce the authority of the active control action by dissipating a portion of the control power. One possible method to improve upon this situation is to use a variable resistor in the shunt circuit and on-line adjust the resistance based on feedback. However, the concurrent design method previously synthesized for APPN systems becomes difficult to implement when such a state-dependent and time-varying resistor is used. In this research, an effective and simple active-parametric control law is developed for an APPN system with variable resistance. The active control law uses a simple but effective rate feedback law along with a feedback linearization technique to compensate for the dynamics of the variable resistor. The parametric control law is designed to turn the resistor off when the active source is supplying power to the actuator and turn the resistor on when necessary to dissipate power from the structure. With this variable resistance action it is possible to retain the passive damping abilities of the APPN circuit while minimizing the amount of control power that is dissipated in the circuit. A series of simulations are conducted in order to demonstrate the increased efficiency due to the variable resistance action. The effects of excitation bandwidth and controller gain on the performance of the system are also examined.
The Application of a Smart Landing Gear Oleo Incorporating Electrorheological Fluid
Authors: Berg C. D. , Wellstead P. E.
Published: August 2009

The objectives of this paper are to outline the use of Electrorheological (ER) fluid within an aerospace system. The advantages of ER fluid-based systems are given followed by design considerations which include those related to the non-linear behaviour of an ER fluid subjected to oscillatory shear. A control strategy is outlined for the use of a smart landing gear (LG) oleo incorporating ER fluid. The paper also considers the issues associated with airworthiness requirements and ER fluid devices.

For airworthiness approval a smart oleo based LG system must primarily be shown to be safe and as such has to be fault tolerant. A major failure for this application would be if the control strategy failed and the oleo damping coefficient was consistently too low; a backup system is therefore incorporated into the design and other potential modes of failure considered.

A semi-active control strategy applied to a variable damping coefficient LG oleo has specific requirements, partly due to the fact that for the take-off and landing phases of flight they are different. A semi-active control strategy is outlined based on the requirements for the alteration of damping coefficient according to the phase of an aircraft's flight. The strategy is the focus of current work to estimate the effectiveness of semi-active vibration control as applied to an undercarriage.
Magnetorheological Throttle Valve in Passive Damping Systems
Authors: Gorodkin S. , Lukianovich A. , Kordonski W.
Published: August 2009

The present paper considers the efficiency of modelling experimental pressureflowrate characteristics of an MR throttle valve by a technique, according to which hydraulic resistance coefficient of a valve is determined as a function of Reynolds and Hedstrdm numbers. In predictions, an MR fluid is characterised by density, out-of-field viscosity and yield stress. It is shown that the hydraulic characteristics of a valve predicted by Hedstrom's technique are fit to the experimental ones over the entire range of magnetic field and MR fluid flowrate. The procedure for prediction of valve parameters that allows a damper design to be optimised is presented.
Magnetorheological Suspension-Based High Precision Finishing Technology (MRF)
Authors: Kordonski William , Golini Don
Published: August 2009

In MRF the mechanical energy for material removal is generated by the hydrodynamic flow of a magnetorheological (MR) polishing suspension throughout a preset converging gap formed by the workpiece surface and a moving rigid wall. MRF reduces the surface microroughness of optical materials to < 10 A. Shape errors are corrected to a fraction of a wavelength of light and subsurface damage is removed.
Conducting Polmers as a Basis for Responsive Materials Systems
Authors: Barisci Joseph N. , Lewis Trevor W. , Spinks Geoffrey M. , Too Chee O. , Wallace Gordon G.
Published: August 2009

Conducting polymers such as polypyrrole and polyaniline are being extensively studied for their use in a wide range of new products. These materials are unique in that they have switchable properties due to their 2 or more mechanically stable oxidation states. Thus, films or coatings can be easily switched by the application of small voltages and currents to change the mechanical and electrical properties, the density, light absorbance and even to emit light in a diode arrangement. This paper reviews the factors that influence the performance of conducting polymers in four applications being developed at the Intelligent Polymer Research Institute: actuators, membranes, sensors and corrosion resistant coatings.
The Dynamic Performance of an Electrorheological Fluid in Squeeze Flow under AC Excitation
Authors: El Wahed Ali K. , Sproston John L. , Stanway Roger
Published: August 2009

This paper is concerned with an experimental comparative assessment of the mechanical performance of an ER fluid in oscillatory squeeze flow under various AC conditions. Interest in this topic arose from the desire to employ the fluid in this way in a shortstroke vibration damper. In this investigation the fluid is sandwiched between two parallel plane electrodes, the upper one being fixed and the lower one vibrating normal to its plane. The magnitude of the transmitted force across the fluid is seen to be highly dependent on the shape of the input waveform, on the mechanical vibration frequency as well as on the electrical excitation frequency and level of applied voltage.
Damage Detection in Structures Using Precursor Transformation Method
Authors: Mehrabi Armin B. , Tabatabai Habib , Lotfi Hamid R.
Published: August 2009

In this paper, a new concept for damage detection and long-term health monitoring of structures is presented. The Precursor Transformation Method (PTM) is based on determining the causes (precursors) of change in the measured state of the structure under non-variable loading conditions (e.g., dead loads in bridges). The PTM concept addresses the inability of the current structural monitoring methods to discriminate, in structural behavior terms, the meaning of voluminous measured sensor data on a timely and cost effective basis. This method offers advantages in sensitivity and cost efficiency when compared to conventional vibration-based or parameter estimation methods. PTM was developed as part of a research project sponsored by the Federal Highway Administration on bridge stay cable condition assessment.

Measured changes in the state of a structure (displacements, strains, internal forces) can be related to precursors through a transformation matrix. This matrix is formed by determining the patterns of change in the state of structure associated with externally imposed strains (temperatures) or displacements representing possible damage scenarios. A finite element model of the undamaged structure is used to calculate these patterns. The use of an undamaged model of the structure in determining damage patterns simplifies the calculation process significantly, while introducing some approximation in results. Theoretical derivations and special case studies indicate that these approximations are limited to second order effects, and in many cases well within measurement and calculation accuracies. Examples using simulated damages on two truss structures and a cable-stayed bridge are also presented.
Detection of Non-Symmetrical Damage in Smart Plate-Like Structures
Authors: Banks H. T. , Emeric P. R.
Published: August 2009

A two-dimensional model for in-plane vibrations of a cantilever plate with a nonsymmetrical damage is used in the context of defect identification in materials with piezoelectric ceramic patches bonded to their surface. These patches can act both as actuators and sensors in a selfanalyzing fashion, which is a characteristic of smart materials. A Galerkin method is used to approximate the dynamic response of these structures. The natural frequency shifts due to the damage are estimated numerically and compared to experimental data obtained from tests on cantilever aluminum plate-like structures damaged at different locations with defects of different depths. The damage location and extent are determined by an enhanced least square identification method. Efficacy of the frequency shift based algorithms is demonstrated using experimental data.
Arrayed Electrostatic Scratch Drive Actuators: Toward Visible Effects up to the Human Scale
Authors: Minotti Patrice , Bourbon Gilles , Langlet Philippe , Masuzawa Takahisa
Published: August 2009

This paper investigates millimeter scale electrostatic motors designed through a new "bottom-up design approach." Active polysilicon sheets involving thousands of elementary scratch drive actuators are analyzed, according to the driving force superposition capabilities of distributed electrostatic actuators. Driving forces as high as 1 00,000 pIN are reported in this paper, using 6 mm2 polysilicon sheets that integrate up to 1430 elementary scratch drive actuators. The mechanical power transmission from the sheet to the external load is also investigated. Because of structural height limitations, active polysilicon sheets do not allow significant driving forces to be transmitted to the external world. Therefore, original architectures, such as tubular electrostatic motors, are proposed using the insertion of a flexible polysilicon stator within the gap of a macroscopic cylindrical joint. An original self-assembling method is used in order to develop a first generation of millimeter scale electrostatic actuators. Expected performances that are evaluated from the in situ sheet characterization (i.e., from characterization onto the silicon wafer) point out the relevance of the bottom-up design methodology proposed in this paper. For the first time, visible effects up to the human scale are conceivable from silicon-based electrostatic motors that will allow innumerable actuation applications to be performed in the near future.
Actuation of Trailing Edge Flap in a Wing Model Using Piezostack Device
Authors: Chandra Ramesh , Chopra Inderjit
Published: August 2009

This paper presents a methodology to actuate trailing edge flap in a wing model using a high performance piezostack device. A composite wing model was built around this piezostack actuator with integrated mechanical amplification. The free displacement and block force of this high voltage actuator were respectively determined as 28 mil and 16 lb at 1000 volts. The linear motion of the actuator was converted to rotary motion for flap actuation using a hinge offset mechanism. This model was tested to evaluate the performance of flap actuation without and with aerodynamic forces. The flap deflection was measured using a Hall sensor, and a maximum of 8.5 deg flap deflection was achieved. The influence of free stream velocity and angle of attack on flap deflection was examined. A 30% decrease in flap deflection at free stream velocity at 95 ft/sec was noticed. Angle of attack of 10 deg did not change the flap deflection. Flap deflection was predicted from force-displacement relation of actuator and calculated hinge moment and good correlation between experiment and prediction was achieved.
Shape Memory Alloys for Passive Vibration Damping
Authors: Fosdick Roger , Ketema Yohannes
Published: August 2009

We study the use of shape memory alloys for the purpose of passive vibration damping in a one degree of freedom oscillator. We assume that the pseudoelastic behavior of the shape memory material is due to a stress-induced phase transformation which is governed by a kinetic relation. We consider both impulsively initiated unforced motions and periodically forced motions. Hysteresis is present in both cases. For a periodically forced motion, a limit cycle is attained after transients die out and we give an example which shows how the energy dissipated per cycle depends on the forcing frequency. We also introduce an "equivalent viscous damping coefficient" and show how it depends on the forcing frequency. This provides a measure of the effectiveness of pseudoelasticity as a damping mechanism. The combined effect of viscous and pseudoelastic damping is briefly discussed.
Locating Structural Damage Using Frequency Response Reference Functions
Authors: Schulz Mark J. , Naser Ahmad S. , Pai P. Frank , Chung Jaycee
Published: August 2009

A technique for monitoring vibration measurements to detect structural damage is presented. Frequency response functions from a healthy structure are measured for reference data, then cross-spectral densities between pairs of combined damage and external forces are computed to detect any occurring damage. The excitation forces are not measured, and can be uniform, random, and uncorrelated, or applied at a single point on the structure. The technique bounds the damage location between the closest sensors on the structure, only a small number of sensors are needed, the damage force is approximated, and no model of the structure is used. For bending vibrations, rotations must also be measured which in practice is often difficult. In a finite-element simulation, the method located small damage and approximated the damage force for a beam structure.
Test Results of Resonant Integrated Microbeam Sensor (RIMS) for Acoustic Emission Monitoring
Authors: Schoess Jeffrey N. , Zook J. David
Published: August 2009

The feasibility of detecting stress-wave acoustic phenomena with Honeywell's resonant microbeam-based MEMS sensor technology is presented. The baseline technical approach described here incorporates an integrated silicon microstructure and a resonant microbeam with micron-level feature size, and features frequency sensitivity up to 500 kHz. The stress-wave acoustic MEMS concept has been demonstrated successfully in the laboratory test environment to sense simulated acoustic emission (AE) events for structural fatigue crack monitoring applications. The technical design approach and laboratory test results are presented.
Flexural Piezoelectric Transducers with Frequency Agility Obtained via Membrane Loads
Authors: Htbert Chad A. , Lesieutre George A.
Published: August 2009

Broadband transducers find uses in many applications. One approach to increasing the bandwidth of a flexural transducer is to add damping to the device, usually decreasing its sensitivity in the process. An alternative approach, useful in some applications, involves active tuning of the natural frequency of a high-sensitivity narrowband device. In this research, membrane loads were used to alter the natural frequencies and electromechanical coupling coefficients of three-layer (trilaminar) piezoelectric ceramic transducers. A coupling coefficient is a measure of the effectiveness with which a piezoelectric material or device converts electrical energy to mechanical energy or vice versa. Applying in-plane loads increased the effectiveness of the transducers by increasing their operating frequency range, while maintaining high coupling coefficients.

Two types of trilaminar flexural piezoceramic transducers were studied: beams and disks. The measured electrical impedance of individual devices was used to determine shortand open-circuit natural frequencies, and then coupling coefficients. In addition, finite element models were developed and used to predict the same quantities. Rotational springs were used in these models to account for non-ideal experimental boundary conditions, while reduction of the piezoelectric material coupling accounted for loss of performance due to stress depoling and aging. Good agreement between experimental data and theory was obtained.

Significant changes in natural frequencies, as well as increases in coupling coefficients were obtained for both beam and disk transducers. Experiments with the trilaminar piezoceramic beams yielded a 36% change in frequency, with an accompanying 38% increase in coupling coefficient. Experiments with the disks yielded a change in frequency of 13%, and an increase in coupling coefficient of 15%. These results demonstrated the feasibility of using membrane loads to improve the frequency-agility of flexural piezoceramic transducers. Candidate applications include acoustic transducers and pneumatic valves.
Properties and Applications of Commercial Magnetorheological Fluids
Authors: Jolly Mark R. , Bender Jonathan W. , Carlson J. David
Published: August 2009

The rheological and magnetic properties of several commercial magnetorheological (MR) fluids are presented and discussed. These fluids are compared using appropriate figures of merit based on conventional design paradigms. Some contemporary applications of MR fluids are discussed. These applications illustrate how various material properties may be balanced to provide optimal performance.
Multi-Objective Optimization of an Adaptive Composite Beam Using the Physical Programming Approach
Authors: Suleman A. , Gonicalves M. A.
Published: August 2009

The objective of this paper is to present the optimization of an adaptive composite structure using the physical programming approach. To this end, a multi-objective optimization problem of an adaptive composite beam with piezoelectric actuators bonded to its surface is performed. The goal is to optimize the size and placement of the actuator pairs, in order to maximize the performance of their actuation power, to minimize the mass of the piezoelectric material and to maintain the required actuation voltages below maximum operating values.

A generalized tri-dimensional version of the Heaviside function has been used to represent the distribution of the piezoelectric actuators. A closed form solution for the equations of equilibrium is presented.

Physical programming presents the following advantages over the more conventional optimization methodologies: reduced computational effort and time, elimination of both iterative selection of weights and prioritization of objective functions.
Shape Control of Laminated Cantilevered Beams with Piezoelectric Actuators
Authors: Wang C. M. , Ang K. K. , Ajit A.
Published: August 2009

Treated herein is the shape control of a composite laminated beam using piezoelectric patch actuators. The first order shear deformation beam theory is used for the analysis to ensure accurate bending solutions. Optimality conditions and analytical expressions are derived for determining the optimal voltages to be applied to the piezoelectric actuators so as to bend the beam to the desired shape. The formulation incorporates upper and lower bounds on the voltages as these voltages are, in practice, constrained due to cost and material constraints. To verify the correctness of the formulation and the optimality conditions, the optimal voltage for the well-known Lee and Moon's piezoelectric cantilevered beam is determined and compared with existing results in the literature. Several shape control problems of laminated beams are solved which include symmetric and asymmetric beams with two sided and one sided piezoelectric patch actuator configurations. As a special case of the more general patch actuator formulation, the problem of determining optimal voltages for a symmetric beam with piezoelectric layered actuators is also solved. The obtained optimal voltages for the various beam problems considered herein may serve also as benchmark results for checking the validity, convergence and accuracy of numerical results obtained by other numerical methods such as the Finite Element Method.
MTDR Monitoring Systems for the Integrity of Infrastructures
Authors: Su Miau-Bin , Chen Yuh-Jyh
Published: August 2009

Most infrastructures are formed by large amount of parts, like members of truss, decks of bridge, and so on. Relative movement including shearing and extension between members causes load redistribution or even failure. Monitoring the integrity of the structural system can assure its performance and safety. MTDR (Metallic Time Domain Reflectometry) is proposed here to be an intelligent monitoring system using one coaxial cable embedded into members as the sensing and conducting media all the way through the monitored structure. Relative movements between each member at the connecting points are monitored simultaneously by sending a fast rise impulse into the cable. This paper presents laboratory measurements necessary to quantitatively interpret the reflected waveform. The type and magnitude of reflected waveform caused by shearing and extension between members were investigated. The interpretive techniques were defined and verified experimentally. Quantification between reflected waveform change and amount of relative movements are achieved and provided.
Intelligent Sensing for Innovative Bridges
Authors: Shehata Emile , Rizkalla Sami
Published: August 2009

This paper discusses two types of fiber optic sensors used for monitoring highway bridges in Manitoba, Canada. The first, the Taylor Bridge, is the longest smart bridge built in North America and was completed in 1997. Four girders, large portions of the deck slab and the barrier wall are reinforced with carbon and glass fiber reinforced polymer (FRP) materials. The bridge is remotely monitored using fiber optic sensors embedded in the girders, the deck slab and the barrier wall to provide continuous information on the health and structural performance of the bridge. Signals obtained from the optical sensors are transmitted through a telephone line, thereby allowing an office-based engineer to monitor the stresses and strains via a computer anywhere in the world. The paper discusses the expert system program used to reduce the data collected from the bridge into engineering information which can be used to assess the performance of the FRP material and the behavior of the bridge.

The second, the Norwood Bridge, is another innovative bridge also built in Winnipeg, Manitoba. The bridge is a complex precast reinforced concrete structure including an innovative mechanical connection at the supports to provide continuity. Monitoring of the bridge was requested by the owner, the City of Winnipeg, to verify structural behavior during different stages of construction and operation. A different type of fiber optic system was used in this bridge. Both the Taylor and the Norwood Bridge projects were undertaken by the Network of Centres of Excellence on Intelligent Sensing for Innovative Structures (ISIS Canada) which was able to provide the valuable link between the emerging new technology in structural remote monitoring and the construction industry.
A Novel Fiber Optic Delamination Detection Scheme: Theoretical and Experimental Feasibility Studies
Authors: Elvin Niell , Leung Christopher K. Y. , Sudarshanam V. S. , Ezekiel Shaoul
Published: August 2009

Delamination detection is important in ensuring the safety and timely repair of structures. In this paper, a novel technique for detecting delamination is proposed. By embedding an optical fiber inside a structural component, the integrated strain along the fiber can be determined. With a load moving along the component, a plot of integrated strain vs load position can be obtained. By correlating changes in the plot with the presence of delaminations, a simple loading test can be employed for delamination detection. The objective of the present investigation is to assess the feasibility of the proposed technique. Experimentally, to ensure the measurement of small length changes as a result of delamination, a highly sensitive interferometer is developed. Laboratory tests are carried out on simply supported beams and beams on elastic foundation. To compare with experimental measurements, finite element analysis is carried out to obtain numerical results. The experimental and numerical results correlate reasonably well with one another. The findings of this investigation demonstrate the potential of the technique and warrant further developments for practical applications.
Calcium Signaling in Neuronal Cells Exposed to the Munitions Compound Cyclotrimethylenetrinitramine (RDX)
Authors: Ehrich Marion , Wu Xiaohua , Werre Stephen R. , Major Michael A. , McCain Wilfred C. , Reddy Gunda
Published: August 2009

Cyclotrimethylenetrinitramine (RDX) has been used extensively as an explosive in military munitions. Mechanisms for seizure production, seen in past animal studies, have not been described. Increased calcium levels contribute to excitotoxicity, so in this study neuroblastoma cells are loaded with calcium-indicating dye before application of 1.5 µM to 7.5 mM RDX, with fluorescence recorded for 30 cycles of 11 seconds each. The lowest concentration of RDX increases calcium fluorescence significantly above baseline for cycles 2 to 8; millimolar concentrations increase calcium fluorescence significantly above baseline for cycles 2 to 30. Increases in calcium, like those of 200 nM carbachol, are prevented with 10 mM of calcium chelator ethylene glycol-bis(β-aminoethyl ether)-N,N,N,N tetra-acetic acid (EGTA, tetrasodium salt). Calcium channel blocker verapamil (20 μM), Ca2+-ATPase inhibitor thapsigargin (5 μM), and general membrane stabilizer lidocaine (10 mM) partially attenuate carbachol- and RDX-induced increases in calcium, suggesting that RDX transiently increases intracellular calcium by multiple mechanisms.
Normative interpretations of diversity
Authors: Lægaard Sune
Published: August 2009

Normative interpretations of particular cases consist of normative principles or values coupled with social theoretical accounts of the empirical facts of the case. The article reviews the most prominent normative interpretations of the Muhammad cartoons controversy over the publication of drawings of the Prophet Muhammad in the Danish newspaper Jyllands-Posten. The controversy was seen as a case of freedom of expression, toleration, racism, (in)civility and (dis)respect, and the article notes different understandings of these principles and how the application of them to the controversy implied different social theoretical accounts of the case. In disagreements between different normative interpretations, appeals are often made to the ‘context’, so it is also considered what roles ‘context’ might play in debates over normative interpretations.
Political cultures compared
Authors: Meer Nasar , Mouritsen Per
Published: August 2009

One outcome of the Muhammad cartoons controversy has been an opportunity for comparative critical examination of public discourse on conceptions of citizenship and belonging vis-à-vis Muslim minorities in different national contexts. In this article, we focus upon the press reaction in two north-western European countries that on first appearance offer radically different cases. While Britain is a formerly imperial power where ‘legitimate’ public articulations of the collective ‘we’ must take stock of the sensibilities in this diverse inheritance, Denmark’s emergence as a modern constitutional state is premised on a cultural, linguistic and ethnic homogeneity. It would only be fair to anticipate, therefore, that any comparison of press discourse on matters of religious minority toleration and respect for difference would herald very different outcomes to these traditions.

Yet this article shows that, on closer inspection, Jyllands-Posten’s more ‘radical’ approach marked a departure from other Danish newspapers in a manner that left it relatively isolated, and that the self-restraint shown by the British press in not reprinting the cartoons was far from universally supported, and subject to significant internal criticism. Indeed, the press discourse in both countries cast the reaction to the cartoons controversy by Muslims themselves as a sign of failed integration, and each moreover stressed a need for civility and respect — even where there was disagreement over the kinds of ‘dialogue’ that should take place. Nevertheless, significant divergences and cleavages remained, and the explanation for these differences rests not only on Britain’s more ‘multicultural’ traditions, but also the experiences of the Rushdie affair and the subsequent debate that had already taken place in Britain. What is striking is the ways in which the Danish discourse appears to be plotting a course that is not that radically different from one taken in the British case, specifically the extent to which a recognition of religious minority sensibilities needs to be offset with a civic incorporation that is cast in interdependent terms in a way that is inclusive of — and not alienating to — Muslims.
The Muhammad cartoons conflict and transnational activism
Authors: Olesen Thomas
Published: August 2009

There are many ways to approach the case of the Muhammad cartoons conflict. This article proposes looking at the conflict as an instance of transnational activism. The conflict started out as a Danish issue — prompted by a Danish newspaper, Jyllands-Posten, and its publication in September 2005 of a series of satirical cartoons of the Prophet Muhammad — but in a matter of months the controversy escalated into a full-blown transnational phenomenon. The aim of the article is not to develop new theory or provide detailed empirical support for the arguments, but rather to indicate a new research agenda on transnational activism. The author hopes that scholars of religion, culture and politics, that is, the core readership of Ethnicities , might find inspiration in such an exercise. The article identifies and addresses four challenges posed by the conflict to the study of transnational activism.
Electrocardiographic left ventricular hypertrophy regression induced by an angiotensin receptor blocker-based regimen in hypertensive patients with diabetes: data from the SARA study
Authors: Barrios Vivencio , Escobar Carlos , Calderón Alberto , Echarri Rocio , Barrios Sara , Navarro-Cid Josefa
Published: August 2009

Introduction. This study examined the influence of diabetes on left ventricular hypertrophy (LVH) detected by different electrocardiographic (ECG) criteria and its changes induced by a 12-month candesartan-based regimen.

Methods. The patients were treated for a 12-month period with a candesartan-based regimen (8/16 mg + hydrochlorothiazide12.5 mg + additional drugs to target blood pressure < 140/90 mmHg [< 130/80 in diabetics]). Cornell voltage index (CorV), Cornell product (CorP), Sokolow-Lyon voltage index (SokV), and Sokolow-Lyon product (SokP) were calculated. In total 276 patients were included, 51 with diabetes.

Results. At study end, blood pressure was reduced 19.0±9.2/7.3±3.4 mmHg in diabetic patients and 18.8±9.1/8.0±3.2 mmHg in non-diabetic subjects (both p<0.01 vs. baseline; p=0.85 between groups).At baseline, 37.5% of diabetic and 26.4% of non-diabetic patients fulfilled criteria of ECG-LVH by CorP (p=0.02), 25.7% and 23.2%, respectively, by SokP (p=0.18), 11.8% and 13.7% by CorV (p=0.16), and 14.3% and 11.6% by SokV (p=0.10).At study end, the prevalence of ECG-LVH was reduced to 25.1% (relative risk reduction [RRR] 33.3%, p=0.001) and 18.2% (RRR 29.2%, p=0.001) by CorP and SokP, in diabetic patients, respectively. In non-diabetic patients, only the CorP criterion showed a significant decrease (RRR 18.9%, p=0.01). No significant changes were observed by other criteria.The RRR of ECG-LVH with treatment was significantly higher in diabetics according to CorP and SokP criteria.

Conclusions. The prevalence of ECG-LVH detected by CorP was higher in diabetics. Diabetics achieved higher reductions in ECG-LVH prevalence than non-diabetics with a candesartan-based regimen.
Rating Scale Items
Authors: Christ Theodore J. , Boice Christina
Published: August 2009

Ratings scales are a common component of many multisource, multimethod frameworks for socioemotional and behavior assessment of children. There is a modest literature base to support the use of attitudinal, behavioral, and personality rating scales. Much of that historic literature focuses on the characteristics and interpretations of specific scales, which are mostly Likert-type scales. There are many more scale types and item types that receive less attention within the literature and less application in practice. This article provides a brief summary of the literature relevant to formats, components, and nomenclature associated with rating scale item types. This article is intended to provide basic information that might inspire and contribute to the development and evaluation of novel rating scales with a variety of item types, especially those relevant to Direct Behavior Rating methods of assessment.
Foundation for the Development and Use of Direct Behavior Rating (DBR) to Assess and Evaluate Student Behavior
Authors: Christ Theodore J. , Riley-Tillman T. Chris , Chafouleas Sandra M.
Published: August 2009

Direct Behavior Rating (DBR) is a method of social—emotional and behavior assessment that combines the immediacy of systematic direct observation and the efficiency of behavior rating scales. The purpose of this article is to discuss the defensibility and usability of DBR. This article provides a brief summary of (a) the past, present, and future directions of social— emotional and behavior assessment methods in schools; (b) the defining features of DBR; (c) the guiding principles for DBR development and evaluation; and (d) DBR research to date. Special emphasis is placed on single-item scale DBR (SIS-DBR) and three general outcome behaviors that are most relevant for use in schools. Research and recommendations for standard SIS-DBR instrumentation and procedures are reviewed, along with future directions for research and practice.
Introduction
Authors: Dörrenbächer Christoph , Becker-Ritterspach Florian
Published: August 2009

Intrafirm competition, production relocation and outsourcing define crucial ways of organising and reorganising the cross-border operations of multinational corporations. What is more: these organisational activities put severe pressure on established economic coordination and governance both in developed as well as in developing countries. However, despite their organisational, political and economic salience, rather little is known about these processes and in particular about their socio-political dimensions. To this end, the contributions of this special issue aim at exploring, first, who the relevant actors are, what their interests are and how their strategies can be captured in intrafirm competition, production relocation and outsourcing. Second, the contributions discuss the wider socio-economic implications of firm-level processes by discussing, for example, the impact of outsourcing and relocation on employment fragmentation. Finally, the importance of public discourses is highlighted with regard to their role in both legitimating and promoting intrafirm competition, production relocation and outsourcing.