bluuebunny/crossref_metadata_2025 huggingface dataset:
Increasing Rates of Psychiatric Publication From Low- and Middle-Income Countries
Authors: Large Matthew , Nielssen Olav , Farooq Saeed , Glozier Nick
Published: August 2009

Objective: The low level of psychiatric research in low- and middle-income (LAMI) countries has been identified as a cause for concern, particularly because the extent of the unmet need for psychiatric treatment in many LAMI countries is not known. The aim of this study was to establish if the worldwide increase in research publication during the last decade included an increase in publication about mental disorders from LAMI countries.

Method: We searched PubMed for articles about mental disorder, depression and schizophrenia using the names of LAMI and high-income (HI) countries in the institutional affi liation address (AD) field published during two five-year periods: 1998—2002 and 2003—2007. We then examined the relationship between per capita publications about mental disorder and the independent variables of per capita gross domestic product purchasing power parity (GDP ppp), per capita psychiatric beds, per capita psychiatrists, total population and whether the country had a designated mental health budget.

Results: The number of medical research publications per capita, and the number of publications about mental disorder from LAMI countries is low when compared to the rate from HI countries. However, the absolute number of publications from LAMI regions and the proportion of research publications about mental disorder, schizophrenia and depression increased significantly during the decade of the study. There were independent associations between GDP ppp and population size and the rate of publications about mental disorder in LAMI countries. Conclusions: The overall increase in the number of publications about mental disorder in the last decade probably reflects an increase in psychiatric research in LAMI countries. The increase in rates of publication was greatest in middle-income countries with the largest populations.
Stigmatization of Mental Illness Among Nigerian Schoolchildren
Authors: Ronzoni Pablo , Dogra Nisha , Omigbodun Olayinka , Bella Tolulope , Atitola Olayinka
Published: August 2009

Background: Despite the fact that about 10% of children experience mental health problems, they tend to hold negative views about mental illness. The objective of this study was to investigate the views of Nigerian schoolchildren towards individuals with mental illness or mental health problems.

Methods: A cross-sectional design was used. Junior and senior secondary schoolchildren from rural and urban southwest Nigeria were asked: ‘What sorts of words or phrases might you use to describe someone who experiences mental health problems?’ The responses were tabulated, grouped and interpreted by qualitative thematic analysis.

Results: Of 164 students, 132 (80.5%) responded to the question. Six major themes emerged from the answers. The most popular descriptions were ‘derogatory terms’ (33%). This was followed by ‘abnormal appearance and behaviour’ (29.6%); ‘don’t know’ answers (13.6%); ‘physical illness and disability’ (13.6%); ‘negative emotional states’ (6.8%); and ‘language and communication difficulties’ (3.4%). Conclusion: The results suggest that, similar to findings elsewhere, stigmatization of mental illness is highly prevalent among Nigerian children. This may be underpinned by lack of knowledge regarding mental health problems and/or fuelled by the media. Educational interventions and encouraging contact with mentally ill persons could play a role in reducing stigma among schoolchildren.
The relationship between heparin level and activated clotting time in the adult cardiac surgery population
Authors: FitzGerald DJ , Patel A , Body SC , Garvin S
Published: August 2009

The purpose of this descriptive study was to examine the relationship between heparin levels (HL) determined by heparin protamine titration (HPT) and activated clotting time (ACT) for cardiopulmonary bypass (CPB) in an adult cardiac surgery population. We examined institutional databases for all patients who underwent CPB at a single US academic institution from February 2005 until July 2007. Baseline ACT, predicted and actual heparin dose response (HDR), target and actual ACT, heparin concentration and heparin bolus dose were recorded. We examined the ACT and HL after the initial heparin bolus dose (Post-Hep) and 10 minutes after the initiation of CPB (CPB+10). The Post-Hep and CPB+10 ACT and HL are reported for 3802 patients. The distribution of ACTs for HL of 0.7, 1.4, 2.0, 2.7 and 3.4 units heparin/mL blood at both time points are reported. Additional analysis of the relationship of HL to ACTs of 300, 350, 400 and 480 seconds is also presented.
Evaluation of air handling in a new generation neonatal oxygenator with integral arterial filter
Authors: Gomez D , Preston TJ , Olshove VF , Phillips AB , Galantowicz ME
Published: August 2009

Prime volume of the cardiopulmonary bypass circuit may lead to significant hemodilution and the potential need for blood products for all patients, but may be more critical in the pediatric and, specifically, the neonatal patient. We report on the first use of the Terumo® CAPIOX® FX05 (Baby-FX™) oxygenator with integral arterial filter, prime volume 43 ml, evaluating performance and air-handling of six Baby-FX™ versus thirteen Baby-RX™ oxygenators. The Terumo Baby-FX™ primes and performs as easily as the Baby-RX™ series. A significant prime component in the neonatal CPB circuit can be the arterial line filter (ALF). Removal of the ALF may lead to significant reduction in prime volume, decreased exposure to foreign surfaces with subsequent reduction in inflammation, and potential elimination or reduction in blood product exposures.
Renal dysfunction in cardiac surgery: identifying potential risk factors
Authors: Barnum JL , Sistino JJ
Published: August 2009

Aprotinin has been associated with increased renal failure and mortality when used in cardiac surgery. The purpose of this retrospective study was to compare the incidence of renal failure and mortality in our patient population to the published rates, accounting for risk factors associated with renal failure. After IRB approval; using the STS Database and cardiopulmonary bypass pump records, a total of 2292 cardiac patients were identified from January 2004 through June 2008. Forty-nine patients were excluded because they were on renal dialysis preoperatively. There were 1226 coronary artery bypass patients. Patients were separated into groups, according to which antifibrinolytic agent was used. This study included a total of 716 patients, divided into three groups; aprotinin ( n = 436), tranexamic acid ( n = 61), and off-pump coronary artery bypass (OPCAB) ( n = 219). Epsilon aminocaproic acid (AMICAR) was given by the anesthesiologist to the majority of the remaining 510 patients and was not recorded on the bypass record. Therefore, patients given AMICAR were not included in this study. Outcomes included renal dialysis after surgery and mortality. Risk factors were identified and compared to patients in a study published by Mangano in the New England Journal of Medicine (N Engl J Med 2006; 354: 353–365). Aprotinin vs. control group showed no significant difference in risk factors for diabetes mellitus, hypertension, creatinine level above 1.3 mg/dl, or low ejection fraction. The percentage of patients requiring renal dialysis and mortality was less in Medical University of South Carolina (MUSC) patients than the other published study. Overall, the patients in the MUSC study had greater risk factors for renal failure, with the exception of patients with preoperative serum creatinine of >1.3 mg/dl (8.3 vs. 15.1%). This study does not show the same risk for renal failure associated with aprotinin that has been published elsewhere.
Review: The Use of Antidepressants in Pregnant and Breastfeeding Women: A Review of Recent Studies
Authors: Kendall-Tackett Kathleen , Hale Thomas W.
Published: August 2009

Antidepressants are one of the most commonly prescribed medications for pregnant and lactating women. However, there have been some recent concerns about their safety. This article summarizes recent research on the impact of untreated depression on the baby, the effects of antidepressants on the baby when prescribed during pregnancy, the short- and longer-term effects of prenatal exposure on infants and children, and the passage of medications into breast milk. Recommendations are made on providing mothers and their health care providers with information so they can make accurate risk/benefit analyses about using these medications while pregnant or breastfeeding.
The Impact of New Employers From the Outside, the Growth of Local Capitalism, and New Amenities on the Social and Economic Welfare of Small Towns
Authors: Besser Terry L. , Recker Nicholas , Parker Matthew
Published: August 2009

The purpose of this study was to determine if the outcomes of economic development result in the anticipated economic and social benefits.The authors differentiated between the proximal outcomes of development (e.g., attracting a new employer) and their distal outcomes (e.g., increased employment and income). Indicators of economic change from secondary sources were merged with primary data from resident surveys and key informants’ interviews for 99 small Iowa towns for the analyses. Findings show that the opening of absentee-owned employers had positive economic benefits compared to the situation in other similar towns. However, it was not accompanied by gains in quality of life. The growth of local capitalism was associated with more positive quality of life outcomes. New amenities were not associated with economic or quality of life changes.
Priest, Blood, Sacrifice: Re-Membering the Maternal Divine
Authors: Green Ali
Published: August 2009

The presence of the woman priest presiding at the Eucharist causes a `collision' with traditional phallocentric Christian rites, not least around blood sacrifice. Sociological, philosophical and psychological research has found this to be a male-only practice designed to control women. I argue that the woman priest brings new and recovered meanings and possibilities relating to the maternal divine that revivify and enrich old interpretations associated with the Eucharist. A doubly gendered priesthood symbolically connects bloodshed not only with violence and death but with birth and nurturing, with nature and with community. Women's priesthood calls for sexual difference to be acknowledged and celebrated within the Christian narrative in a way that allows both women and men to flourish as children of God.
Redemption from Mother Nature to Our Father the Lord?* An Ecofeminist Analysis of Hymns in the Swedish Church Edition of Psalmer i 2000-talet
Authors: Samuelsson Maria Jansdotter
Published: August 2009

The feminist critical deconstruction of Western culture and theology written by Luce Irigaray could be said to represent a certain branch of ecofeminist perspectives on religion. The article analyses the symbolic structures of suppression of women, body and nature and the exaltation of spirit, culture and the androcentric God, inherent in four hymns included in the new supplement (2006) to the book of hymns in the Lutheran Church of Sweden. The analysis shows that these symbolic structures are visible also in these more recent hymns, even though they can be said to also consider and bring out women's experiences. Despite their `feminist' approach, they have not, on any deeper level, affected the subordination of women and the nature-given.
Her Blue Body*: A Pagan Reading of Alice Walker Womanism
Authors: Razak Arisika
Published: August 2009

This essay explores the earth-based woman-centered paganism found in Alice Walker's womanist writings. It argues that Walker's visionary landscape is influenced by indigenous spirituality and woman-centered Goddess beliefs which place humans in a sacred web of life that includes plants, animals, elemental forces, the earth, the cosmos, and the living and the dead. In this landscape, humans are not stewards of creation, but members of the whole. A review of several of her visionary novels— including The Temple of My Familiar, By the Light of My Father's Smile and The Color Purple—suggest that Walker links women's erotic freedom, social and cultural liberation, and sexual and spiritual redemption. She rejects dualistic notions which oppose spirituality and sexuality, and through characters who embody transgressive sexuality, she suggests that a fully enjoyed and empowered female sexuality is a gateway to the perception of the divine as well as a path to healing, self-love and authenticity. A self-declared pagan, her holistic framework integrates the personal, sexual, spiritual, and cosmic with the needs of the earth and all sentient life.
Actuation Properties of Electrochemically Driven Polypyrrole Free-Standing Films
Authors: Chiarelli P. , Santa A. Della , de Rossi D. , Mazzoldi A.
Published: August 2009

In this paper we report about investigations on coupled electrochemomechanical phenomena in polypyrrole (PPy) free-standing films. Quantitative measurements of isotonic length and relaxed elastic modulus changes are performed on PPy samples during cyclic voltammetry and square-wave amperometry. The link between dimensional and mechanical changes in the samples and doping salt exchange kinetics is investigated and a possible interpretation is proposed.
Piezoelectric Ultrasonic Motors
Authors: Wallaschek Jorg
Published: August 2009

Piezoelectric ultrasonic motors are a new type of actuator. They are characterized by high torque at low rotational speed, simple mechanical design and good controllability. They also provide a high holding torque even if no power is applied. Compared to electromagnetic actuators the torque per volume ratio of piezoelectric ultrasonic motors can be higher by an order of magnitude. Recently various types of piezoelectric ultrasonic motors have been developed for industrial applications such as cameralens drive or as actuator in the head restraint of automobile seats. This paper describes several types of piezoelectric ultrasonic motors. In the first part the working principle of the travelling wave motor is explained. In the second part other types of piezoelectric ultrasonic motors are described and classified with respect to the vibration modes and contact mechanisms used in their design. Finally some open problems in piezoelectric ultrasonic motor research are addressed.
Effect of Driving Field and Temperature on the Response Behavior of Ferroelectric Actuator and Sensor Materials
Authors: Zhang Q. M , Wang H. , Zhao J.
Published: August 2009

Three commonly used ferroelectric actuator and sensor materials, namely polyvinylidene fluoride copolymers, lead zirconate titanate piezoceramics (PZT), and lead magnesium niobate-lead titanate relaxors (PMN-PT) at low PT content, are characterized with respect to temperature and driving field amplitude. It is shown that changes in the response and loss with the driving field amplitude are mainly caused by irreversible process and hysteresis effect in the materials, which are different from a nonlinear process. To analyze the driving field amplitude dependence of the response of a piezoelectric material, a representation is proposed which divides the material response behavior into three regions with increased driving field amplitude: 1) a linear response region, 2) a region with increased response sensitivity, nonlinearity and hysteresis, and 3) a saturation and depoling region. Based on this, the operating field limit is clearly defined for different materials and different applications. For ferroelectric relaxor materials, since the magnitude of the field induced piezoelectric coefficients depends on both the dielectric constant and the polarization level, a material with a smaller difference between the temperatures of depolarization and dielectric constant maximum will yield higher piezoelectric constants. In addition, the relaxor materials exhibit large nonlinear effects which may be useful in smart materials and structures.
Heat Transfer Considerations for Couette Devices Operating with Electro Structured Fluids
Authors: Smyth R. , Bullough W. A. , Lim L. K. , Makin J.
Published: August 2009

A numerical solution for the outflow of heat from a cylindrical clutch type of device is used to show the effects of the various significant dimensions, fluid characteristics, and running arrangements for unexcited operation. In the first instance the fluid is considered to be isothermal and in the second the radial temperature distribution across it is calculated. In this second case the average temperature of the film flow is now established and the effect of the various parameters examined with the whole film viscosity taken at this average temperature.

Results are verified from experimental data acquired from a single acting clutch using two fluids and speeds.
Truss Structure Integrity Identification Using PZT Sensor-Actuator
Authors: Sun F. P. , Chaudhry Z. , Liang C. , Rogers C. A.
Published: August 2009

This paper presents a frequency domain impedance-signature-based technique for health monitoring of an assembled truss structure. Unlike conventional modal analysis approaches, the technique uses piezoceramic (PZT) elements as integrated sensor-actuators for acquisition of signature pattern of the truss. The concept of the localization of sensing/actuation area for damage detection of an assembled structure is presented for the first time. Through a PZT patch bonded to a truss node and the measurement of its electric admittance, which is coupled with the mechanical impedance of the truss, the signature pattern of a truss is monitored. The admittance of a truss in question is compared with that of the original healthy truss. Statistic algorithm is then applied to extract a damage index of the truss based on the signature pattern difference. Experimental proof that over a selected band, the detection range of a bonded PZT sensor on a truss is highly constrained to its immediate neighborhood is presented. This characteristic allows accurate determination of the damage location in a complex real-world structure with a minimum mathematical modeling and numerical computation.
Crack Growth in Ferroelectric Ceramics Driven by Cyclic Polarization Switching
Authors: Lynch C. S. , Chen L. , Suo Z. , Mcmeeking R. M. , Yang W.
Published: August 2009

Ferroelectric ceramics are susceptible to stable crack growth under cyclic electric field of high magnitude. The stresses originate from mismatch strains induced by the electric field around inhomogeneities, such as processing flaws, terminated electrodes and the cracks themselves. The phenomenon is studied using a lead lanthanum zirconate-titanate ceramic. A flaw is indented on the surface of a ceramic sample. Subject to a cyclic electric field of magnitude exceeding the coercive field, cracks eminate from the flaw, in the direction perpendicular to the voltage drop. Tests relevant to the phenomenon are also performed. Polarization and strain as functions of applied electric field are measured at various temperatures and applied stresses. Discharge is demonstrated through an air gap between two ceramic plates subjected to a voltage drop. Models are presented that explain the cyclic nature of the crack growth.
Adaptive Composite Materials with Shape Memory Alloy Actuators for Cylinders and Pressure Vessels
Authors: Paine Jeffrey S. N. , Rogers Craig A. , Smith Randy A.
Published: August 2009

An investigation of adaptive hybrid composite cylinders utilizing active Shape Memory Alloy (SMA) composite layers for use in high-pressure vessel applications is presented. An analytical analysis using a linear elastic composite cylinder formulation shows that adapative SMA elements in a composite cylinder can be used to actively reduce peak tensile hoop stresses in the composite cylinder inner walls. Lower peak hoop stresses are produced by using the active SMA elements to create a compound cylinder effect. Significant reductions in peak tensile stresses can be accomplished using the adaptive compound cylinder effect. The resulting hoop stresses in the thickwall composite are also more efficiently loaded through-out the cylinder wall thickness. With the adaptive hybrid composite materials, high-pressure composite cylinders can be produced which have lower levels of radial expansion. A model for the adaptive composite material cylinder and representative stress states for various composite materials is presented. Parametric studies were performed to demonstrate the utility of the adaptive composite cylinder concept for various composite materials and pressure vessel configurations.
Manufacturing of Adaptive Graphite/Epoxy Structures with Embedded Nitinol Wires
Authors: Hebda D. A. , Whitlock M. E. , Ditman J. B. , White S. R.
Published: August 2009

Shape memory alloy (SMA) composites are a class of smart materials in which embedded nitinol wires are used as actuators. Previous research in SMA composites has been limited to wires using one-way shape memory behavior. The objective of this paper is to assess the feasibility of using two-way shape memory (TWSM) training of nitinol, a nickel-titanium SMA, wires for their use as embedded actuators in SMA composites and to investigate the effects of processing conditions on SMA composite quality and actuation ability. Training of the TWSM behavior in nitinol was investigated for a range of initial strains and training cycles. In each case, over 50% of the initial strain can be recovered after training and trained response is generally stable after about 30 training cycles. SMA composite specimens were manufactured using either hot press or autoclave methods and several different types of cure cycles. Voids were found to congregate near the embedded wire surface and can typically be as high as 10% in these regions. Using a staged-cure cycle, the average void content was reduced to 1.3-1.5%. The effect of the composite cure cycle was found to have no significant effect on trained nitinol wire behavior. Finally, the structural behavior of an SMA composite beam was investigated by actuating wires through electrical resistance heating. The tip deflection of a cantilevered beam was found to be primarily composed of SMA transformational effects, however, some localized heating was evident.
Open Loop Compensation in a Stack-Mass Positioning System
Authors: Duong Khanh , Garcia Ephrahim
Published: August 2009

A piezoceramic stack-mass positioning system was tested with different frequencies and voltages for its response to different input conditions. It is observed that the response of the positioning system varied with different input conditions. A technique is developed to compensate for this variation by the use of an open loop compensator. This open loop controller is able to compensate for the phase lag inherent in the stack-mass system, thereby improving its dynamic response and position resolution.
One-Dimensional Analytical Constant Parameter Linear Electromagnetic-Magnetomechanical Models of a Cylindrical Magnetostrictive (Terfenol-D) Transducer
Authors: Hall David L. , Flatau Alison B.
Published: August 2009

A method is presented for including motional and eddy current effects when analytically modeling electrical impedance functions of cylindrical magnetostrictive transducers. To approximate eddy current effects, onedimensional analytical constant parameter linear electromagnetic models of a cylindrical magnetostrictive transducer are developed. Maxwell's equations are solved for the magnetic field strength as a function of radial position. Closed form expressions for magnetic flux as a function of radial position are then derived, from which transducer electrical impedance functions are formulated. Two different physical models of the transducer are considered. The first model results in the classic eddy current solution for a rod in a wound wire solenoid. The second physical model includes the effects of a conducting external cylindrical housing. Motional effects are incorporated into the electromagnetic models via the magnetomechanical model, which is a frequency and load dependent, complex valued expression for the "dynamic magnetic permeability" of the magnetostrictive material within the transducer. The functional form for this dynamic magnetic permeability is derived by comparing the transduction equations for the magnetostrictive material with those for the transducer containing the material. Electrical impedance functions for both physical models are compared with an experimental measurement for a particular magnetostrictive transducer (using Terfenol-D) in its low signal linear range of operation. The second physical model was found to offer the better simulation of the experimental measurement of the transducer's electrical impedance, with errors in magnitude or phase of less than + 5% for excitation frequencies between 100 and 10,000 Hz (the asrun mechanical resonant frequency was 8800 Hz). Experience has shown that measured material parameters typically yield simulations of electrical impedance functions within i 10%. Predictions of electrical impedance functions for Terfenol-D transducers, calculated based on estimated or published Terfenol-D parameters, can be in error by well over 40%. Thus, the accuracy of model results seem to be controlled primarily by the accuracy with which magnetostrictive material parameters are known.
Anisotropic Actuation with Piezoelectric Fiber Composites
Authors: Bent Aaron A. , Hagood Nesbitt W. , Rodgers John P.
Published: August 2009

An investigation was made into the field of planar structural actuation with anisotropic active materials. The mechanisms for creating anisotropic actuators were discussed, and the impact of anisotropy was shown at the individual lamina level and at the laminated structure level. Models for laminated structures were developed using an augmented Classical Laminated Plate Theory incorporating induced stress terms to accommodate anisotropic actuator materials. A twistextension coupled laminate was used to exemplify how twist can be directly induced into isotropic host structures using anisotropic actuation. Four anisotropic actuators with different material anisotropies were compared using this example. Finally, a laminate incorporating piezoelectric fiber composite actuators was manufactured and tested. Excellent agreement was found between the predicted and experimental response.
Free Response of a Thermally Driven, Composite Actuator
Authors: Wirtz R. A. , Gordaninejad F. , Wu Weida
Published: August 2009

A thermally driven force/displacement actuator may be fabricated from a composite consisting of a shape memory alloy (SMA) and an elastomer. A simple onedimensional device is described where a thin layer of SMA overlays an elastomer which is in turn bonded to a heat sink. A thermal response model is developed which includes the martensite fraction of the SMA, in addition to the effects of heat capacity of the composite and conductive resistance of the elastomer. Solutions, in terms of temperature-composition-time trajectories, for free response are obtained using different phase transition models. Calculations for a device consisting of Nitinol overlaying a typical elastomer show that rapid response, coupled with small power consumption, may be achieved if device size is kept small.
Vibration Control of a Cylindrical Shell Using Piezoelectric Actuators
Authors: Tani Junji , Qiu Jinhao , Miura Hidehisa
Published: August 2009

This paper presents a method to control the vibration of a cylindrical shell system. The cylindrical shell system consists of a layer of plastic film and two layers of piezoelectric film, a part of which is used as the actuator. This study presents the analysis of vibration problem caused by periodic excitation. The problem is solved by means of the modal expansion method. A numerical simulation and an experiment of vibration control are performed by applying.<,(control theory to the cylindrical shell system. The result shows the effectiveness for the suppression of the forced vibration of the cylindrical shell system by using this control method.
Comparison of Different Impedance-Based Models for Out-of-Phase Actuation of Actuators Bonded on Ring Structures
Authors: Lalande Frederic , Chaudhry Zaffir , Rogers Craig A.
Published: August 2009

Two different impedance models representing out-of-phase actuation of induced strain actuators bonded to the surface of a circular ring are compared. The first impedance model derivation is based on the use of eigenfunctions to determine the structural impedance of the ring, while the second model is based on modal expansion. A discussion of the proper way to apply the equivalent loading due to the out-of-phase actuation is done. A finite element analysis using piezoelectric elements is performed. A comparison between the impedance modeling and the more conventional static modeling approach is also made. Based on the governing equations derivation, the equivalent actuator loading can be included either as an induced uniform moment over the footprint of the actuators or as an external line moment at the ends of the actuators. A dynamic finite element analysis is performed using ANSYS 5.0 piezoelectric elements. The structural responses predicted by both eigenfunctions and modal expansion impedance models show a good match with those obtained using finite element analysis.
Design Considerations for a Strain Actuated Adaptive Wing for Aeroelastic Control
Authors: Lin Charrissa Y. , Crawley Edward F.
Published: August 2009

The dominant issues in the preliminary design of a strain actuated aeroelastic wing are examined. First, the scaling parameter for piezoelectric actuation authority is obtained and used to extrapolate strain actuation variables from an earlier model. Second, the interaction of composite fiber angle and geometric sweep angle is studied, specifically the effect of these parameters on the passive aeroelastic behavior and potential closedloop actuation authority. Finally, a taper ratio trade is completed to understand the effect of varying taper ratio on the passive and active aeroelastic characteristics.
Smart Structural Composites with Monofilament, Piezoelectric Sensors
Authors: Cheng S. -J. , Timm D. C. , Lu Y. , Shaikh N. , Ianno N. J.
Published: August 2009

Smart materials or structures have embedded sensors to monitor their own state as well as environmental stimuli. A novel sensor was developed by sputtering a piezoelectric film onto a conductive fiber or metal wire. This sensor, similar in configuration to an optical fiber, is active since an electric field is developed when strained. Several of these sensors were embedded into a cantilevered beam and a filamentwound cylinder made from AS4/ Epon 828 composites. A variety of test cases were used to demonstrate its sensing feasibility, including free and forced vibrations and acoustic emissions.
Development of a Modal Model for Simultaneous Active and Passive Piezoelectric Vibration Suppression
Authors: Agnes Gregory S.
Published: August 2009

The use of piezoelectric materials simultaneously as passive single-mode devices and active broadband actuators to suppress structural vibrations is discussed. A simple modal model that predicts this behavior is developed. Experimental studies conducted to verify the model show a reduction of 20 dB in the response of the second mode of the structure is possible via passive shunting while simultaneously commanding the piezoactuator. The results indicate that for vibration problems involving a few modes, piezoelectric devices combining active and passive techniques can significantly reduce the broadband structural response to disturbances.
Analytical Modeling of Electrorheological Material Based Adaptive Beams
Authors: Yalcintas Melek , Coulter John P.
Published: August 2009

The use of electrorheological (ER) materials in adaptive structures has received much attention recently. ER adaptive structures are based on controlling the pre-yield rheology of the ER material, which is achieved by applying different electrical fields to the ER material. In this study the dynamic behavior of an ER material based adaptive beam was modeled. Previous modeling efforts were extended towards a more detailed analysis of modal results. The adaptive beams focused on were composed of three layers: an ER material controllable damping layer and surrounding upper and lower elastic plates. A structural model of the assembly in a transverse continuous vibration mode subjected to simply supported boundary conditions was developed and analyzed. It was assumed that each structure was subjected to sinusoidal actuation applied at one or two locations. The model was tested under the conditions of varying forcing frequency from 0-300 Hz, and applied electrical field from 0-3.5 kV/mm. Time domain displacement response, natural frequencies, and loss factors of the structures at varying electric fields and varying damping layer thicknesses were obtained. The analytical results of the adaptive beam were compared with experimental results under the same physical conditions. Qualitative agreement between theory and experimentation resulted. In addition an effort was made to reduce the vibration of the structure by selecting the optimum electrical field which yields minimized vibration for each excitation frequency.
An Adaptive Beam Model with Electrorheological Material Based Applications
Authors: Yalcintas Melek , Coulter John P.
Published: August 2009

In this investigation a theoretical model for adaptive beam structures with various boundary conditions was developed, and its potential applicability to electrorheological (ER) material based adaptive beams was introduced. The cross-sectional configuration of the beam selected was based on sandwiching a damping material between elastic face plates. The transverse continuous vibration model developed is based on thin plate theory. In the model shear and rotary inertia effects are neglected, and it is assumed that no slipping between the elastic layers and the damping layer occurs. All layers are considered to have the same transverse displacement. The resulting analytical model is able to predict the structural vibration response at any location on the beam surface, and is applicable to generalized sets of boundary conditions. In this study, different boundary and external excitation conditions were considered. The transverse vibration response was studied for different boundary conditions. Variations in the mode shapes, natural frequencies, and loss factors, as functions of mode number and excitation frequency, were analyzed. ER material based adaptive beam semi-active vibration control capabilities were analyzed from the observed model results.
Automated Signal Monitoring Using Neural Networks in a Smart Structural System
Authors: Chen Stuart S. , Kim Sungkon
Published: August 2009

Automated health monitoring of instrumented structures will require an appropriate suite of information processing techniques. One such technique, involving Quickprop neural networks, is developed to identify and locate structural damage in a 3D steel truss-type structure instrumented with accelerometers and strain gauges. In experiments conducted in a structural testing laboratory, transient vibration tests caused by impact hammer strikes were conducted on the instrumented structure which was subjected to various damage scenarios. Results of the investigation indicate that neural networks provide a promising approach as one component of the computational tool kit required for on-line autonomous health monitoring of instrumented structures. Anticipating the need for such a comprehensive tool kit, a computational framework for automated signal monitoring is proposed and introduced as well. This framework incorporates signal processors based on neural networks in an object-oriented model for structural monitoring and diagnosis.
Multivariable Neural Network Based Controllers for Smart Structures
Authors: Damle Rajendra , Rao Vittal , Kern Frank
Published: August 2009

This paper details identification and robust control of smart structures using artificial neural networks. To demonstrate the use of artificial neural networks in the control of smart structural systems, two smart structure test articles were fabricated. Active materials like piezoelectric (PZT), polyvinylidene (PVDF) and shape memory alloys (SMA) were used as actuators and sensors. The Eigensystem Realization Algorithm (ERA), a structural identification method has been utilized to determine a minimal order discrete time state space model of the test articles. The ERA requires the Markov parameters of the physical system. A neural network based method has been developed to estimate the Markov parameters of a multi input multi output system from experimental test data. The accelerated adaptive learning rate algorithm and the adaptive activation function were utilized to improve the learning characteristics of the network and reduce the learning time. The identified models were used to design a robust controllers for vibration suppression of smart structures using a modified Linear Quadratic Gaussian with Loop Transfer Recovery (LQG/LTR) method. This control design methodology has better loop transfer recovery properties while accommodating the limited control force available from the SMA and the PZT actuators. This controller was copied into a feedforward neural network using the connectionist approach. This neural network controller was implemented using a PC based data acquisition system. The closed loop performance and robustness properties of the conventional and the neural network based controller are compared experimentally.
Galvanomagnetic Effects in Lateral p+-n Diode Structure
Authors: Nedev N. , Smirnov N.
Published: August 2009

The magnetic field influence on the operation of a p+-n diode structure with two base contacts on the upper surface which are laterally and symmetrically positioned relative to the injecting p+ region has been studied using the finite difference method. This analysis is important for the design of bipolar magnetic field sensors. Results for the changes of the potential distribution and of the electron and hole concentrations caused by a magnetic field applied perpendicular to the device cross section are presented. The influence of some geometric (device thickness, distance between electrodes) and physical (carrier mobility, surface recombination rates) parameters on the device operation is studied.
Coupled Micro to Macro Analysis of a Composite That Hosts Embedded Piezoelectric Actuators
Authors: Shalev Doron , Aboudi Jacob
Published: August 2009

A coupled micro-macromechanical approach is employed to model a fiber reinforced composite actuated by distributed piezoelectric patches. The coupled electromechanical behavior of the piezoelectric patch is formulated. The microstructures of the fiber reinforced composite and the piezoelectric composite are analyzed, and their mutual influence on the performance of the entire composite structure is estimated. Different cases of voltages, piezoelectric volume fractions and number of composite layers are studied. In-plane stresses across the composite thickness are presented to illustrate the resulting responses.
Prediction and Measurement of Modal Damping of Laminated Composite Beams with Piezoceramic Sensor/Actuator
Authors: Kang Young Kyu , Park Hyun Chul , Hwang Woonbong , Han Kyung Seop
Published: August 2009

Damping factor and modal damping of carbon/epoxy laminated composite beams with the piezoceramic sensor and actuator are predicted theoretically and measured experimentally. Finite element method is used for the analysis of dynamic characteristics of the laminated composite beams with and without the piezoceramics. The impulse technique is applied to measure the fundamental frequency, the damping ratio and the modal damping for the first bending mode of the beams. When a pair of piezoceramics is attached to the clamping side of the beam as a sensor and an actuator, the damping and the stiffness of the beam are changed. Taking into account the damping and the stiffness of the adhesive layer and the piezoceramics in the finite element modeling, damping ratio, fundamental frequency and modal damping are in good agreement with those of the measured values. To investigate the effects of sensor/actuator dynamics, vibration analysis of the beam without piezoceramics is also carried out. Damping ratio, fundamental frequency and modal damping of the beams without piezoceramics agree very well with those of measured values, as for the beams with piezoceramics. It is suggested that the modal damping (2w) is a more appropriate performance index rather than the damping ratio (O) for the vibration suppression in the structure, since one of the goals of structural vibration control is to suppress vibrational amplitude as fast as possible and the modal damping is directly related to the settling time of the vibration.
Control of Broadband Acoustic Radiation with Adaptive Structures
Authors: Smith Jerome P. , Fuller Chris R. , Burdisso Ricardo A.
Published: August 2009

Active Structural Acoustic Control has been demonstrated for harmonic disturbances on various structures. This paper presents an extension of this work to the attenuation of acoustic radiation from planar structures subject to broadband disturbances. An adaptive, multiinput multi-output (MIMO), feedforward broadband acoustic control system has been developed. The control approach is the least mean squares (LMS) algorithm. The compensators are adaptive finite impulse response (FIR) filters. The control inputs are implemented with piezoceramic actuators. Both far-field microphones and polyvinylidene fluoride (PVDF) distributed structural sensors are used as error sensors. Both the actuator locations and the PVDF sensor configurations were optimally chosen to minimize radiated sound power assuming multiple frequency excitation. The disturbance is band-limited zero mean white noise and is implemented with a point force shaker. In the control of harmonically excited systems, satisfactory attenuation is possible with a single-input single-output (SISO) controller. In contrast, for systems excited with broadband disturbances, a MIMO controller is necessary for significant acoustic attenuation. Experimental results for the control of a simply supported plate are presented.
Vibration Suppression in a Flexible Structure Based on Fiber Optics Michelson Interferometric Sensor
Authors: Chien Pie-Yau , Chang Yau-Sheng , Chang Ming-Wen
Published: August 2009

A two-wavelength fiber optics Michelson interferometric sensor has been employed to detect the vibration signal in a flexible beam. The synthetic wavelength and synthetic heterodyne detection schemes have been adopted for signal processing on optical phase detection. The active control technique was also developed and implemented to suppress the vibration signal that was generated from the piezoelectric transducer. A 38 dB suppression has been obtained.
Application of Single Mode Optical Fiber Sensors in Structural Vibration Suppression
Authors: Yang S. M. , Chen C. W.
Published: August 2009

Optical fibers are small, lightweight, and flexible that can operate over a wide range of environmental conditions and respond to many physical properties. This paper presents two single-mode Michelson interferometric optical fiber sensors for the vibration control application of smart structures. Analysis and experiment show that the length and location of the sensing fiber in the smart structure has to be carefully selected such that the structural vibration amplitude is within the sensor measurement range for linear output. Experiments are also conducted by feeding back the fiber sensor signal to the piezoelectric actuator embedded inside the smart structure so as to suppress structural vibration. The results show that both optical fiber sensors-one with an external piezoelectric modulator and the other with an internal frequency modulated light source-are effective in vibration control application.
Numerical Analysis of Asymmetrical-Core Two-Mode Fiber Interferometers Subjected to Bending
Authors: de Almeida SéRgio Frascino Muller , de Oliveira Costa António Marcos , Carrara Sidney Luiz Alessi
Published: August 2009

A finite element formulation for solving the scalar wave equation is described. The proposed formulation leads to an eigenvalue problem defined in terms of positive definite matrices. Therefore, convergence of the two first eigenvectors/eigenvalues to modes LP01 and LP1, and their correspondent propagation constants is guaranteed. A computer code was written to implement the finite element formulation. The software assembles the matrix eigenvalue problem and solves it either with the sub-space iteration method or the power iteration method. The software also computes the coordinates of the centroid of the modal field distribution of each mode. The finite element model can be used to assess the effects of bending the optical fiber about an arbitrary axis on the guided light. The numerical analysis accounts for the mechanical deformation of the fiber cross section and the variation of the refractive index profile due to all strain components present in pure bending.

A comparison of the analyses of light propagation in the fiber under unstrained and strained conditions enables one to estimate the bend sensitivity of a two-mode fiber interferometer. Numerical results confirm experimental observations that a small asymmetry of the core index profile may lead to a significant bend sensitivity of a two-mode fiber interferometer. The present model was used to assess the influence of several parameters on the bend sensitivity of an asymmetrical core two-mode fiber interferometer. The excellent agreement between the numerical and experimental results indicates that this numerical model is a reliable tool to analyze the effect of bending strains in twomode fiber interferometers.
Simplifications and Comparisons of Shape Memory Alloy Constitutive Models
Authors: Brinson L. C. , Huang M. S.
Published: August 2009

Here we will present a simplification of the form of one popular shape memory alloy (SMA) constitutive model. This simplification allows a more compact written form and hence easier calculations with the one-dimensional SMA constitutive law first developed by Tanaka, later modified by Liang and Rogers, and again by Brinson. In addition, a new derivation of the model will be given based on micromechanics. In this context, comparisons between the Tanaka and two other models will be presented and implications discussed. It will be shown that the constitutive models are in fact quite similar, and that the important distinction between these SMA models is primarily in the formulation of the transformation kinetics. Several examples will be presented utilizing the models.
Pseudoelastic Hysteresis in Martensitic Reorientation of Cu-Zn-AI Polycrystalline Shape Memory Alloys
Authors: Yan W. -Y. , Sun Q. -P. , Hwang K. -C.
Published: August 2009

The stress-induced martensitic reorientation of two kinds of Cu-Zn-Al polycrystalline shape memory alloys were studied through experiment. Special attention was paid to the deformation behavior of these polycrystals during the reorientation. Experimental result indicates that for the two materials after reorientation the deformation is pseudoelastic as long as applied stress is smaller than the prestress that induced the reorientation. Detailed research on the pseudoelastic hysteresis was performed. The experimental phenomena are very similar to that of the pseudoelasticity of shape memory alloys due to the forward and reverse martensitic transformations at high temperature.