WorldWideScience

Sample records for performance piezo composites

  1. Analytical design model for a piezo-composite unimorph actuator and its verification using lightweight piezo-composite curved actuators

    Science.gov (United States)

    Yoon, K. J.; Park, K. H.; Lee, S. K.; Goo, N. S.; Park, H. C.

    2004-06-01

    This paper describes an analytical design model for a layered piezo-composite unimorph actuator and its numerical and experimental verification using a LIPCA (lightweight piezo-composite curved actuator) that is lighter than other conventional piezo-composite type actuators. The LIPCA is composed of top fiber composite layers with high modulus and low CTE (coefficient of thermal expansion), a middle PZT ceramic wafer, and base layers with low modulus and high CTE. The advantages of the LIPCA design are to replace the heavy metal layer of THUNDER by lightweight fiber-reinforced plastic layers without compromising the generation of high force and large displacement and to have design flexibility by selecting the fiber direction and the number of prepreg layers. In addition to the lightweight advantage and design flexibility, the proposed device can be manufactured without adhesive layers when we use a resin prepreg system. A piezo-actuation model for a laminate with piezo-electric material layers and fiber composite layers is proposed to predict the curvature and residual stress of the LIPCA. To predict the actuation displacement of the LIPCA with curvature, a finite element analysis method using the proposed piezo-actuation model is introduced. The predicted deformations are in good agreement with the experimental ones.

  2. Highly sensitive piezo-resistive graphite nanoplatelet-carbon nanotube hybrids/polydimethylsilicone composites with improved conductive network construction.

    Science.gov (United States)

    Zhao, Hang; Bai, Jinbo

    2015-05-13

    The constructions of internal conductive network are dependent on microstructures of conductive fillers, determining various electrical performances of composites. Here, we present the advanced graphite nanoplatelet-carbon nanotube hybrids/polydimethylsilicone (GCHs/PDMS) composites with high piezo-resistive performance. GCH particles were synthesized by the catalyst chemical vapor deposition approach. The synthesized GCHs can be well dispersed in the matrix through the mechanical blending process. Due to the exfoliated GNP and aligned CNTs coupling structure, the flexible composite shows an ultralow percolation threshold (0.64 vol %) and high piezo-resistive sensitivity (gauge factor ∼ 10(3) and pressure sensitivity ∼ 0.6 kPa(-1)). Slight motions of finger can be detected and distinguished accurately using the composite film as a typical wearable sensor. These results indicate that designing the internal conductive network could be a reasonable strategy to improve the piezo-resistive performance of composites.

  3. Effects of cyclic impacts on the performance of a piezo-composite electricity generating element in a d33 mode energy harvesting.

    Science.gov (United States)

    Pham, Van Lai; Ha, Ngoc San; Goo, Nam Seo; Choo, Jinkyo F

    2014-10-01

    The increasing use of piezoelectric generators to harvest energy from various ambient sources requires the establishment of durability data for piezoelectric materials. In this paper, a d3 mode piezocomposite electricity generating element (PCGE) was tested for its durability under cyclic impact loading. For this purpose, a motor driven lever system was designed to apply constant impact force on PCGEs. To investigate the durability of PCGEs, the output voltage of the PCGEs was observed upon repeated application of an impact force until eventual loss of the generated voltage. The experimental results enabled to determine the number of cycles until which PCGEs can be used without loss of their electricity generation performance with respect to the stress level applied on the PCGEs. At low stress level (around 0.76 MPa or lower), the PCGE showed almost insignificant degradation even after 2 million cycles whereas degradation occurred sooner (after 8 x 10(5) cycles) at higher stress levels (around 0.92 MPa or higher). The effects of impact loading on the durability of the PCGEs were also examined by X-ray photographs of the specimens.

  4. A Study on AE Signal Analysis of Composite Materials Using Matrix Piezo Electric Sensor

    International Nuclear Information System (INIS)

    Yu, Yeun Ho; Choi, Jin Ho; Kweon, Jin Hwe

    2007-01-01

    As fiber reinforced composite materials are widely used in aircraft, space structures and robot arms, the study on non-destructive testing methods has become an important research area for improving their reliability and safety. AE (acoustic emission) can evaluate the defects by detecting the emitting strain energy when elastic waves are generated by the initiation and growth of crack, plastic deformation, fiber breakage, matrix cleavage, or delamination. In the paper, AE signals generated under uniaxial tension were measured and analyzed using the 8x8 matrix piezo electric sensor. The electronic circuit to control the transmitting distance of AE signals was designed and constructed. The optical data storage system was also designed to store the AE signal of 64 channels using LED (light emitting diode) elements. From the tests, it was shown that the source location and propagation path of AE signals in composite materials could be detected effectively by the 8x8 matrix piezo electric sensor

  5. Design and manufacture of a lightweight piezo-composite curved actuator

    Science.gov (United States)

    Yoon, K. Joon; Shin, Seokjun; Park, Hoon C.; Goo, Nam Seo

    2002-02-01

    In this paper we are concerned with the design, manufacture and performance test of a lightweight piezo-composite curved actuator (called LIPCA) using a top carbon fiber composite layer with near-zero coefficient of thermal expansion (CTE), a middle PZT ceramic wafer, and a bottom glass/epoxy layer with a high CTE. The main point of the design for LIPCA is to replace the heavy metal layers of THUNDERTM by lightweight fiber reinforced plastic layers without losing the capabilities for generating high force and large displacement. It is possible to save up to about 40% of the weight if we replace the metallic backing material by the light fiber composite layer. We can also have design flexibility by selecting the fiber direction and the size of prepreg layers. In addition to the lightweight advantage and design flexibility, the proposed device can be manufactured without adhesive layers when we use an epoxy resin prepreg system. Glass/epoxy prepregs, a ceramic wafer with electrode surfaces, and a carbon prepreg were simply stacked and cured at an elevated temperature (177 °C) after following an autoclave bagging process. We found that the manufactured composite laminate device had a sufficient curvature after being detached from a flat mould. An analysis method using the classical lamination theory is presented to predict the curvature of LIPCA after curing at an elevated temperature. The predicted curvatures are in quite good agreement with the experimental values. In order to investigate the merits of LIPCA, performance tests of both LIPCA and THUNDERTM have been conducted under the same boundary conditions. From the experimental actuation tests, it was observed that the developed actuator could generate larger actuation displacement than THUNDERTM.

  6. Class-D amplifier design and performance for driving a Piezo Actuator Drive servomotor

    DEFF Research Database (Denmark)

    Zsurzsan, Tiberiu-Gabriel; Zhang, Zhe; Andersen, Michael A. E.

    2016-01-01

    This paper investigates the behavior of piezoelectric stacks in a Piezoelectric Actuator Drive (PAD) motor, which shows non-linear equivalent impedance and has a dramatic impact on the overall system performance. Therefore, in this paper, the piezo stackt’s model is discussed and an improved large...

  7. Performance and Mechanism of Piezo-Catalytic Degradation of 4-Chlorophenol: Finding of Effective Piezo-Dechlorination.

    Science.gov (United States)

    Lan, Shenyu; Feng, Jinxi; Xiong, Ya; Tian, Shuanghong; Liu, Shengwei; Kong, Lingjun

    2017-06-06

    Piezo-catalysis was first used to degrade a nondye pollutant, 4-chlorophenol (4-CP). In this process, hydrothermally synthesized tetragonal BaTiO 3 nano/micrometer-sized particles were used as the piezo-catalyst, and the ultrasonic irradiation with low frequency was selected as the vibration energy to cause the deformation of tetragonal BaTiO 3 . It was found that the piezoelectric potential from the deformation could not only successfully degrade 4-chlorophenol but also effectively dechlorinate it at the same time, and five kinds of dechlorinated intermediates, hydroquinone, benzoquinone, phenol, cyclohexanone, and cyclohexanol, were determined. This is the first sample of piezo-dechlorination. Although various active species, including h + , e - , •H, •OH, •O 2 - , 1 O 2 , and H 2 O 2 , were generated in the piezoelectric process, it was confirmed by ESR, scavenger studies, and LC-MS that the degradation and dechlorination were mainly attributed to •OH radicals. These •OH radicals were chiefly derived from the electron reduction of O 2 , partly from the hole oxidation of H 2 O. These results indicated that the piezo-catalysis was an emerging and effective advanced oxidation technology for degradation and dechlorination of organic pollutants.

  8. Impact damage detection in light composite sandwich panels using piezo-based nonlinear vibro-acoustic modulations

    International Nuclear Information System (INIS)

    Pieczonka, L; Ukowski, P; Klepka, A; Staszewski, W J; Uhl, T; Aymerich, F

    2014-01-01

    The nonlinear vibro-acoustic modulation technique is used for impact damage detection in light composite sandwich panels. The method utilizes piezo-based low-frequency vibration and high-frequency ultrasonic excitations. The work presented focuses on the analysis of modulation intensity. The results show that the method can be used for impact damage detection reliably separating damage-related from vibro-acoustic modulations from other intrinsic nonlinear modulations. (paper)

  9. Piezo1

    Science.gov (United States)

    Gottlieb, Philip A.; Sachs, Frederick

    2012-01-01

    Piezo ion channels have been found to be essential for mechanical responses in cells. These channels were first shown to exist in Neuro2A cells, and the gene was identified by siRNAs that diminished the mechanical response. Piezo channels are approximately 2500 amino acids long, have between 24–32 transmembrane regions, and appear to assemble into tetramers and require no other proteins for activity. They have a reversal potential around 0 mV and show voltage dependent inactivation. The channel is constitutively active in liposomes, indicating that no cytoskeletal elements are required. Heterologous expression of the Piezo protein can create mechanical sensitivity in otherwise insensitive cells. Piezo1 currents in outside-out patches were blocked by the extracellular MSC inhibitor peptide GsMTx4. Both enantiomeric forms of GsMTx4 inhibited channel activity in a manner similar to endogenous mechanical channels. Piezo1 can adopt a tonic (non-inactivating) form with repeated stimulation. The transition to the non-inactivating form generally occurs in large groups of channels, indicating that the channels exist in domains, and once the domain is compromised, the members simultaneously adopt new properties. Piezo proteins are associated with physiological responses in cells, such as the reaction to noxious stimulus of Drosophila larvae. Recent work measuring cell crowding, shows that Piezo1 is essential for the removal of extra cells without apoptosis. Piezo1 mutations have also been linked to the pathological response of red blood cells in a genetic disease called Xerocytosis. These finding suggest that Piezo1 is a key player in cells’ responses to mechanical stimuli. PMID:22790400

  10. Enhanced Performance of a Self-Powered Organic/Inorganic Photodetector by Pyro-Phototronic and Piezo-Phototronic Effects.

    Science.gov (United States)

    Peng, Wenbo; Wang, Xingfu; Yu, Ruomeng; Dai, Yejing; Zou, Haiyang; Wang, Aurelia C; He, Yongning; Wang, Zhong Lin

    2017-06-01

    Self-powered photodetectors (PDs) have long been realized by utilizing photovoltaic effect and their performances can be effectively enhanced by introducing the piezo-phototronic effect. Recently, a novel pyro-phototronic effect is invented as an alternative approach for performance enhancement of self-powered PDs. Here, a self-powered organic/inorganic PD is demonstrated and the influences of externally applied strain on the pyro-phototronic and the photovoltaic effects are thoroughly investigated. Under 325 nm 2.30 mW cm -2 UV illumination and at a -0.45% compressive strain, the PD's photocurrent is dramatically enhanced from ≈14.5 to ≈103 nA by combining the pyro-phototronic and piezo-phototronic effects together, showing a significant improvement of over 600%. Theoretical simulations have been carried out via the finite element method to propose the underlying working mechanism. Moreover, the pyro-phototronic effect can be introduced by applying a -0.45% compressive strain to greatly enhance the PD's response to 442 nm illumination, including photocurrent, rise time, and fall time. This work provides in-depth understandings about the pyro-phototronic and the piezo-phototronic effects on the performances of self-powered PD to light sources with different wavelengths and indicates huge potential of these two effects in optoelectronic devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Optimizing performance of silicon-based p-n junction photodetectors by the piezo-phototronic effect.

    Science.gov (United States)

    Wang, Zhaona; Yu, Ruomeng; Wen, Xiaonan; Liu, Ying; Pan, Caofeng; Wu, Wenzhuo; Wang, Zhong Lin

    2014-12-23

    Silicon-based p-n junction photodetectors (PDs) play an essential role in optoelectronic applications for photosensing due to their outstanding compatibility with well-developed integrated circuit technology. The piezo-phototronic effect, a three-way coupling effect among semiconductor properties, piezoelectric polarizations, and photon excitation, has been demonstrated as an effective approach to tune/modulate the generation, separation, and recombination of photogenerated electron-hole pairs during optoelectronic processes in piezoelectric-semiconductor materials. Here, we utilize the strain-induced piezo-polarization charges in a piezoelectric n-ZnO layer to modulate the optoelectronic process initiated in a p-Si layer and thus optimize the performances of p-Si/ZnO NWs hybridized photodetectors for visible sensing via tuning the transport property of charge carriers across the Si/ZnO heterojunction interface. The maximum photoresponsivity R of 7.1 A/W and fastest rising time of 101 ms were obtained from these PDs when applying an external compressive strain of -0.10‰ on the ZnO NWs, corresponding to relative enhancement of 177% in R and shortening to 87% in response time, respectively. These results indicate a promising method to enhance/optimize the performances of non-piezoelectric semiconductor material (e.g., Si) based optoelectronic devices by the piezo-phototronic effect.

  12. Enhanced Luminescence Performance of Quantum Wells by Coupling Piezo-Phototronic with Plasmonic Effects.

    Science.gov (United States)

    Huang, Xin; Jiang, Chunyan; Du, Chunhua; Jing, Liang; Liu, Mengmeng; Hu, Weiguo; Wang, Zhong Lin

    2016-12-27

    With a promising prospect of light-emitting diodes as an attractive alternative to conventional light sources, remaining challenges still cannot be addressed owing to their limited efficiency. Among the continued scientific efforts, significant improvement on the emission efficiency has been achieved via either piezo-phototronic effect-based strain modulation or resonant excitation of plasmons in metallic nanostructures. Here, we present the investigation on the coupling process between piezo-phototronic effect and localized surface plasmonic resonance for enhancing the photoluminescence of InGaN/GaN quantum wells coated with Ag nanoparticles. The underlying physical mechanism of experimental results originates from tuning plasmonic resonance controlled by the shift of emission wavelength via piezo-phototronic effect, and it is further confirmed with the support of theoretical calculations. As a result, our research provides an approach to the integration of plasmonics with piezo-phototronic effect and brings widespread applications to high-efficiency artificial lighting, on-chip integrated plasmonic circuits, subwavelength optical communication, and micro-optoelectronic mechanical systems.

  13. Ultra-Precision Measurement and Control of Angle Motion in Piezo-Based Platforms Using Strain Gauge Sensors and a Robust Composite Controller

    Science.gov (United States)

    Liu, Lei; Bai, Yu-Guang; Zhang, Da-Li; Wu, Zhi-Gang

    2013-01-01

    The measurement and control strategy of a piezo-based platform by using strain gauge sensors (SGS) and a robust composite controller is investigated in this paper. First, the experimental setup is constructed by using a piezo-based platform, SGS sensors, an AD5435 platform and two voltage amplifiers. Then, the measurement strategy to measure the tip/tilt angles accurately in the order of sub-μrad is presented. A comprehensive composite control strategy design to enhance the tracking accuracy with a novel driving principle is also proposed. Finally, an experiment is presented to validate the measurement and control strategy. The experimental results demonstrate that the proposed measurement and control strategy provides accurate angle motion with a root mean square (RMS) error of 0.21 μrad, which is approximately equal to the noise level. PMID:23860316

  14. Ultra-Precision Measurement and Control of Angle Motion in Piezo-Based Platforms Using Strain Gauge Sensors and a Robust Composite Controller

    Directory of Open Access Journals (Sweden)

    Zhi-Gang Wu

    2013-07-01

    Full Text Available The measurement and control strategy of a piezo-based platform by using strain gauge sensors (SGS and a robust composite controller is investigated in this paper. First, the experimental setup is constructed by using a piezo-based platform, SGS sensors, an AD5435 platform and two voltage amplifiers. Then, the measurement strategy to measure the tip/tilt angles accurately in the order of sub-μrad is presented. A comprehensive composite control strategy design to enhance the tracking accuracy with a novel driving principle is also proposed. Finally, an experiment is presented to validate the measurement and control strategy. The experimental results demonstrate that the proposed measurement and control strategy provides accurate angle motion with a root mean square (RMS error of 0.21 μrad, which is approximately equal to the noise level.

  15. Thermoelectrically induced nonlinear free vibration analysis of piezo laminated composite conical shell panel with random fiber orientation

    Directory of Open Access Journals (Sweden)

    Lal Achchhe

    2017-09-01

    Full Text Available This paper presents the free vibration response of piezo laminated composite geometrically nonlinear conical shell panel subjected to a thermo-electrical loading. The temperature field is assumed to be a uniform distribution over the shell surface and through the shell thickness and the electric field is assumed to be the transverse component E2 only. The material properties are assumed to be independent of the temperature and the electric field. The basic formulation is based on higher order shear deformation plate theory (HSDT with von-Karman nonlinearity. A C0 nonlinear finite element method based on direct iterative approach is outlined and applied to solve nonlinear generalized eigenvalue problem. Parametric studies are carried out to examine the effect of amplitude ratios, stacking sequences, cone angles, piezoelectric layers, applied voltages, circumferential length to thickness ratios, change in temperatures and support boundary conditions on the nonlinear natural frequency of laminated conical shell panels. The present outlined approach has been validated with those available results in the literature.

  16. Piezo-Stellantrieb

    OpenAIRE

    Mehlkopp, K.

    1992-01-01

    Piezo actuators are used for example in so-called fast tool servo systems with which tools can be fed at high frequency. The disadvantage here is the heat loss occurring in the piezo element increasing with rising frequency. Thus, the maximum feed frequency of such piezo actuators is limited. In order to permit high feed frequencies with the piezo actuator, the temperature of the piezo element is adapted to the ambient temperature of the piezo element. As a result of this thermal stabilizatio...

  17. On the design of 1-3 piezo-composites using topology optimization

    DEFF Research Database (Denmark)

    Sigmund, Ole; Torquato, S.; Aksay, I.A.

    1998-01-01

    (h)((*))g(h)((*)), and the electromechanical coupling factor k(h)((*)). The piezocomposite consists of piezoelectric rods embedded in an optimal polymer matrix. We use the topology optimization method to design the optimal (porous) matrix microstructure. When we design for maximum d(h)((*)) and d(h)((*))g(h)((*)) the optimal transversally......We use a topology optimization method to design 1-3 piezocomposites with optimal performance characteristics for hydrophone applications. The performance characteristics we focus on are the hydrostatic charge coefficient d(h)((*)), the hydrophone figure of merit d...

  18. Piezo-electrostrictive ceramics

    International Nuclear Information System (INIS)

    Kim, Ho Gi; Shin, Byeong Cheol

    1991-09-01

    This book deals with principle and the case of application of piezo-electrostrictive ceramics, which includes definition of piezoelectric materials and production and development of piezoelectric materials, coexistence of Pb(zr, Ti)O 3 ceramics on cause of coexistence in MPB PZT ceramics, electrostrictive effect of oxide type perovskite, practical piezo-electrostrictive materials, and breaking strength, evaluation technique of piezoelectric characteristic, and piezoelectric accelerometer sensor like printer head, ink jet and piezoelectric relay.

  19. Transduction of Repetitive Mechanical Stimuli by Piezo1 and Piezo2 Ion Channels

    Directory of Open Access Journals (Sweden)

    Amanda H. Lewis

    2017-06-01

    Full Text Available Several cell types experience repetitive mechanical stimuli, including vein endothelial cells during pulsating blood flow, inner ear hair cells upon sound exposure, and skin cells and their innervating dorsal root ganglion (DRG neurons when sweeping across a textured surface or touching a vibrating object. While mechanosensitive Piezo ion channels have been clearly implicated in sensing static touch, their roles in transducing repetitive stimulations are less clear. Here, we perform electrophysiological recordings of heterologously expressed mouse Piezo1 and Piezo2 responding to repetitive mechanical stimulations. We find that both channels function as pronounced frequency filters whose transduction efficiencies vary with stimulus frequency, waveform, and duration. We then use numerical simulations and human disease-related point mutations to demonstrate that channel inactivation is the molecular mechanism underlying frequency filtering and further show that frequency filtering is conserved in rapidly adapting mouse DRG neurons. Our results give insight into the potential contributions of Piezos in transducing repetitive mechanical stimuli.

  20. Piezotronics and piezo-phototronics

    CERN Document Server

    Wang, Zhong Lin

    2014-01-01

    This book introduces the fundamentals of piezotronics and piezo-phototronics, and shows how the functionality of piezotroics and piezo-phototronics are complementary to CMOS technology. Describes applications in sensing, nanorobotics and many other areas.

  1. Demystifying Mechanosensitive Piezo Ion Channels.

    Science.gov (United States)

    Xu, X Z Shawn

    2016-06-01

    Mechanosensitive channels mediate touch, hearing, proprioception, and blood pressure regulation. Piezo proteins, including Piezo1 and Piezo2, represent a new class of mechanosensitive channels that have been reported to play key roles in most, if not all, of these modalities. The structural architecture and molecular mechanisms by which Piezos act as mechanosensitive channels, however, remain mysterious. Two new studies have now provided critical insights into the atomic structure and molecular basis of the ion permeation and mechano-gating properties of the Piezo1 channel.

  2. Predicting the losses and the efficiency of a 1-3 piezo-composite transducer through a partial homogeneization method

    Directory of Open Access Journals (Sweden)

    Pastor, J.

    2002-02-01

    Full Text Available The topic of this work is the theoretical study of a disc-shaped acoustic transducer made with a 1-3 piezoelectric composite material. This material consists of PZT ceramic rods embedded in a polymer matrix. A modeling of this ideal transversally periodic structure is proposed. It is based on a finite element approach derived from homogenization techniques mainly used for composite material studies. The analysis focuses on a representative unit cell with specific boundary conditions on the lateral surfaces taking accurately into account the periodicity of the structure. The first step proposed is the development of a three-dimensional Fortran code with complex variables, especially adapted for this problem. Using the principle of correspondence of Lee-Mandel, this technique allows the prediction of the damping properties of the transducer from the complex modulus of the constituents. Both the versatility of the method and the rigorous character of the model are pointed out through various boundary conditions and mixed loadings. An interesting result is that, despite the lossy polymer matrix, a 1-3 composite can advantageously replace a much heavier massive transducer, in terms of efficiency and loss factor.

    El objetivo de este trabajo es el estudio teórico de un transductor acústico con forma de disco construido con un composite piezoeléctrico 1-3. Este material consiste en barras cerámicas de PZT embebidas en una matriz polimérica. Se propone un modelo de su estructura periódica transversal ideal basándose en una aproximación mediante elementos finitos derivada de técnicas de homogeneización usadas principalmente para estudios de materiales compuestos. El análisis se enfoca a una celdilla unidad representativa con unas condiciones de contorno específicas sobre las superficies laterales, teniendo en cuenta adecuadamente la periodicidad de la estructura. El primer paso propuesto es el desarrollo de un código Fortran

  3. The Development of Piezo-Driven Tools for Cellular Piercing

    Directory of Open Access Journals (Sweden)

    Changhai Ru

    2016-10-01

    Full Text Available Conventionally, intracytoplasmic sperm injection (ICSI in the mouse is conducted with piezo-drills that use a droplet of mercury for damping. The use of mercury causes concerns of toxicity and contamination. Although Fluorinert can be used as a substitute for mercury to reduce piezo-drill’s lateral vibration, the damping effect is not as satisfactory as mercury. In this work, a modified piezo-drill without using mercury was developed for the cellular piercing of mouse oocytes. Experimentally, appropriate parameters of driving voltage and frequency were obtained for the penetration of the zona pellucida of mouse oocytes. Furthermore, the lateral vibration of the injection pipette is lower than 1 μm in deionized water, which is not observable at 400 magnificence. With the piezo-drill without using mercury, the system performs the cellular piercing of mouse oocytes with a maximum cleavage rate of 94.7% (n = 117.

  4. A Study on Detection of Elastic Wave Using Patch Type Piezo-Polymer Sensor

    International Nuclear Information System (INIS)

    Kim, Ki Bok; Yoon, Dong Jin; Kueon, Jae Hwa; Lee, Young Seop

    2004-01-01

    Patch type piezo-polymer sensors for smart structures were experimented to detect elastic wave. The pencil lead braking test was performed to analyze the characteristics of patch-type piezo-polymer sensors such as polyvinyliden fluoride (PVDF) and polyvinylidene fluoride trifluorethylene (P(VDF-TrFE)) for several test specimens with various elastic wave velocities and acoustical impedances. The characteristics of the patch-type piezo-polymer sensor were compared with the commercial PZT acoustic emission (AE) sensor. The vacuum grease and epoxy resin were used as a couplant for the acoustic impedance matching between the sensor and specimen. The peak amplitude of elastic wave increased as the diameter of piezo-film and acoustical impedance of the specimen increased. The frequency detection range of the piezo-film sensors decreased with increasing diameter of the piezo-film sensor. The P(VDF-TrFE) sensor was more sensitive than the PVDF sensor

  5. Features of the piezo-phototronic effect on optoelectronic devices based on wurtzite semiconductor nanowires.

    Science.gov (United States)

    Yang, Qing; Wu, Yuanpeng; Liu, Ying; Pan, Caofeng; Wang, Zhong Lin

    2014-02-21

    The piezo-phototronic effect, a three way coupling effect of piezoelectric, semiconductor and photonic properties in non-central symmetric semiconductor materials, utilizing the piezo-potential as a "gate" voltage to tune the charge transport/generation/recombination and modulate the performance of optoelectronic devices, has formed a new field and attracted lots of interest recently. The mechanism was verified in various optoelectronic devices such as light emitting diodes (LEDs), photodetectors and solar cells etc. The fast development and dramatic increasing interest in the piezo-phototronic field not only demonstrate the way the piezo-phototronic effects work, but also indicate the strong need for further research in the physical mechanism and potential applications. Furthermore, it is important to distinguish the contribution of the piezo-phototronic effect from other factors induced by external strain such as piezoresistance, band shifting or contact area change, which also affect the carrier behaviour and device performance. In this perspective, we review our recent progress on piezo-phototronics and especially focus on pointing out the features of piezo-phototronic effect in four aspects: I-V characteristics; c-axis orientation; influence of illumination; and modulation of carrier behaviour. Finally we proposed several criteria for describing the contribution made by the piezo-phototronic effect to the performance of optoelectronic devices. This systematic analysis and comparison will not only help give an in-depth understanding of the piezo-phototronic effect, but also work as guide for the design of devices in related areas.

  6. The amplitude modulation of laser diode emission with antireflection piezo films on mirrors

    International Nuclear Information System (INIS)

    Abrarov, S.M.; Karimov, Kh.S.; Akhmedov, Kh.M.

    2001-01-01

    Present article is devoted to amplitude modulation of laser diode emission with antireflection piezo films on mirrors. The modulator based on laser diode and the emission amplitude modulation of which is performed by electric field impact on antireflection piezo films applied on mirrors was studied.

  7. Progress in piezo-phototronic effect modulated photovoltaics.

    Science.gov (United States)

    Que, Miaoling; Zhou, Ranran; Wang, Xiandi; Yuan, Zuqing; Hu, Guofeng; Pan, Caofeng

    2016-11-02

    Wurtzite structured materials, like ZnO, GaN, CdS, and InN, simultaneously possess semiconductor and piezoelectric properties. The inner-crystal piezopotential induced by external strain can effectively tune/control the carrier generation, transport and separation/combination processes at the metal-semiconductor contact or p-n junction, which is called the piezo-phototronic effect. This effect can efficiently enhance the performance of photovoltaic devices based on piezoelectric semiconductor materials by utilizing the piezo-polarization charges at the junction induced by straining, which can modulate the energy band of the piezoelectric material and then accelerate or prevent the separation process of the photon-generated electrons and vacancies. This paper introduces the fundamental physics principles of the piezo-phototronic effect, and reviews recent progress in piezo-phototronic effect enhanced solar cells, including solar cells based on semiconductor nanowire, organic/inorganic materials, quantum dots, and perovskite. The piezo-phototronic effect is suggested as a suitable basis for the development of an innovative method to enhance the performance of solar cells based on piezoelectric semiconductors by applied extrinsic strains, which might be appropriate for fundamental research and potential applications in various areas of optoelectronics.

  8. Spray-controlled combustionprocess with piezo injection; Strahlgefuehrtes Brennverfahren mit Piezo-Benzineinspritzung

    Energy Technology Data Exchange (ETDEWEB)

    Schaupp, U.; Altenschmidt, F.; Bertsch, D.; Laudenbach, N. [DaimlerChrysler AG, Stuttgart (Germany)

    2007-07-01

    The novel 2nd generation injection system of Mercedes-Benz have resulted in reduced fuel consumption and lower emissions while improving the engine performance. The piezo technology is a great technical advance. The characteristic field range in which stratified charge operation is possible has been extended since the first generation of injection systems. Lower fuel consumption is achieved not only in normal traffic but also when cruising on motorways at constant speed. The advantages are noticeable not only in the test cycle but also in real operation. The piezo injection valve was not available on the market and had to be constructed, including the 200 bar high-pressure fuel injection system. The stability of the injection system and the good mixing characteristics resulted in an optimally combustible mixture at the spark plug. Apart from stability in stratified charge operation, the possibility of multiple injection also has further advantages and potentials in terms of consumption and emissions. (orig.)

  9. Piezo-Phototronic Effect in a Quantum Well Structure.

    Science.gov (United States)

    Huang, Xin; Du, Chunhua; Zhou, Yongli; Jiang, Chunyan; Pu, Xiong; Liu, Wei; Hu, Weiguo; Chen, Hong; Wang, Zhong Lin

    2016-05-24

    With enhancements in the performance of optoelectronic devices, the field of piezo-phototronics has attracted much attention, and several theoretical works have been reported based on semiclassical models. At present, the feature size of optoelectronic devices are rapidly shrinking toward several tens of nanometers, which results in the quantum confinement effect. Starting from the basic piezoelectricity equation, Schrödinger equation, Poisson equation, and Fermi's golden rule, a self-consistent theoretical model is proposed to study the piezo-phototronic effect in the framework of perturbation theory in quantum mechanics. The validity and universality of this model are well-proven with photoluminescence measurements in a single GaN/InGaN quantum well and multiple GaN/InGaN quantum wells. This study provides important insight into the working principle of nanoscale piezo-phototronic devices as well as guidance for the future device design.

  10. Fabrication Effects on Polysilicon-based Micro cantilever Piezo resistivity for Biological Sensing Application

    International Nuclear Information System (INIS)

    Nina Korlina Madzhi; Balkish Natra; Mastura Sidek; Khuan, L.Y.; Anuar Ahmad

    2011-01-01

    In principle, adsorption of biological molecules on a functionalized surface of a micro fabricated cantilever will cause a surface stress and consequently the cantilever bending. In this work, four different type of polysilicon-based piezo resistive micro cantilever sensors were designed to increase the sensitivity of the micro cantilevers sensor because the forces involved is very small. The design and optimization was performed by using finite element analysis to maximize the relative resistance changes of the piezo resistors as a function of the cantilever vertical displacements. The resistivity of the piezo resistivity micro cantilevers was analyzed before and after dicing process. The maximum resistance changes were systematically investigated by varying the piezo resistor length. The results show that although the thickness of piezo resistor was the same at 0.5 μm the resistance value was varied. (author)

  11. A universal piezo-driven ultrasonic cell microinjection system.

    Science.gov (United States)

    Huang, Haibo; Mills, James K; Lu, Cong; Sun, Dong

    2011-08-01

    Over the past decade, the rapid development of biotechnologies such as gene injection, in-vitro fertilization, intracytoplasmic sperm injection (ICSI) and drug development have led to great demand for highly automated, high precision equipment for microinjection. Recently a new cell injection technology using piezo-driven pipettes with a very small mercury column was proposed and successfully applied in ICSI to a variety of mammal species. Although this technique significantly improves the survival rates of the ICSI process, shortcomings due to the toxicity of mercury and damage to the cell membrane due to large lateral tip oscillations of the injector pipette may limit its application. In this paper, a new cell injection system for automatic batch injection of suspended cells is developed. A new design of the piezo-driven cell injector is proposed for automated suspended cell injection. This new piezo-driven cell injector design relocates the piezo oscillation actuator to the injector pipette which eliminates the vibration effect on other parts of the micromanipulator. A small piezo stack is sufficient to perform the cell injection process. Harmful lateral tip oscillations of the injector pipette are reduced substantially without the use of a mercury column. Furthermore, ultrasonic vibration micro-dissection (UVM) theory is utilized to analyze the piezo-driven cell injection process, and the source of the lateral oscillations of the injector pipette is investigated. From preliminary experiments of cell injection of a large number of zebrafish embryos (n = 200), the injector pipette can easily pierce through the cell membrane at a low injection speed and almost no deformation of the cell wall, and with a high success rate(96%) and survival rate(80.7%) This new injection approach shows good potential for precision injection with less damage to the injected cells.

  12. Piezo-generator integrating a vertical array of GaN nanowires.

    Science.gov (United States)

    Jamond, N; Chrétien, P; Houzé, F; Lu, L; Largeau, L; Maugain, O; Travers, L; Harmand, J C; Glas, F; Lefeuvre, E; Tchernycheva, M; Gogneau, N

    2016-08-12

    We demonstrate the first piezo-generator integrating a vertical array of GaN nanowires (NWs). We perform a systematic multi-scale analysis, going from single wire properties to macroscopic device fabrication and characterization, which allows us to establish for GaN NWs the relationship between the material properties and the piezo-generation, and to propose an efficient piezo-generator design. The piezo-conversion of individual MBE-grown p-doped GaN NWs in a dense array is assessed by atomic force microscopy (AFM) equipped with a Resiscope module yielding an average output voltage of 228 ± 120 mV and a maximum value of 350 mV generated per NW. In the case of p-doped GaN NWs, the piezo-generation is achieved when a positive piezo-potential is created inside the nanostructures, i.e. when the NWs are submitted to compressive deformation. The understanding of the piezo-generation mechanism in our GaN NWs, gained from AFM analyses, is applied to design a piezo-generator operated under compressive strain. The device consists of NW arrays of several square millimeters in size embedded into spin-on glass with a Schottky contact for rectification and collection of piezo-generated carriers. The generator delivers a maximum power density of ∼12.7 mW cm(-3). This value sets the new state of the art for piezo-generators based on GaN NWs and more generally on nitride NWs, and offers promising prospects for the use of GaN NWs as high-efficiency ultra-compact energy harvesters.

  13. High-performance composite chocolate

    Science.gov (United States)

    Dean, Julian; Thomson, Katrin; Hollands, Lisa; Bates, Joanna; Carter, Melvyn; Freeman, Colin; Kapranos, Plato; Goodall, Russell

    2013-07-01

    The performance of any engineering component depends on and is limited by the properties of the material from which it is fabricated. It is crucial for engineering students to understand these material properties, interpret them and select the right material for the right application. In this paper we present a new method to engage students with the material selection process. In a competition-based practical, first-year undergraduate students design, cost and cast composite chocolate samples to maximize a particular performance criterion. The same activity could be adapted for any level of education to introduce the subject of materials properties and their effects on the material chosen for specific applications.

  14. GEC Ferranti piezo vibratory gyroscope

    Science.gov (United States)

    Nuttall, J. D.

    1993-01-01

    Prototypes of a piezo-electric vibratory angular rate transducer (gyroscope) (PVG) have been constructed and evaluated. The construction is on the lines suggested by Burdess. The sensitive element is a cylinder of radially poled piezo-electric ceramic. The cylinder is metallized inside and out, and the outer metallization is divided into eight electrodes. The metallization on the inside is earthed. A phase locked loop, using pairs of the electrodes, causes the cylinder to vibrate in one of its two fundamental, degenerate modes. In the presence of rotation, some of the vibration is coupled into the outer mode. This can be detected, or suppressed with a closed-up technique and provides a measure of rotation rate. The gyroscope provides a number of advantages over rotating mass and optical instruments: low size and mass, lower power consumption, potentially high reliability, potentially good dormancy, low cost and high maximum rate.

  15. Progress in piezotronics and piezo-phototronics

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhong Lin [School of Material Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia (United States)

    2012-09-04

    The fundamental principle of piezotronics and piezo-phototronics were introduced by Wang in 2007 and 2010, respectively. Due to the polarization of ions in a crystal that has non-central symmetry in materials such as the wurtzite structured ZnO, GaN and InN, a piezoelectric potential (piezopotential) is created in the crystal by applying a stress. Owing to the simultaneous possession of piezoelectricity and semiconductor properties, the piezopotential created in the crystal has a strong effect on the carrier transport at the interface/junction. Piezotronics is about the devices fabricated using the piezopotential as a ''gate'' voltage to tune/control charge carrier transport at a contact or junction. The piezo-phototronic effect is to use the piezopotential to control the carrier generation, transport, separation and/or recombination for improving the performance of optoelectronic devices, such as photon detector, solar cell and LED. This manuscript reviews the updated progress in the two new fields. A perspective is given about their potential applications in sensors, human-silicon technology interfacing, MEMS, nanorobotics and energy sciences. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. FO hydrophone with hydrostatic pressure compensation: comparative experiment with a conventional piezo hydrophone

    NARCIS (Netherlands)

    Cheng, L.K.; Bruijn, D. de

    1998-01-01

    This paper presents the performance of a TPD FO hydrophone with hydrostatic pressure compensation. In particularly a comparison with a conventional piezo hydrophone system is discussed. ©2003 Copyright SPIE

  17. Pressure tracking control of vehicle ABS using piezo valve modulator

    Science.gov (United States)

    Jeon, Juncheol; Choi, Seung-Bok

    2011-03-01

    This paper presents a wheel slip control for the ABS(anti-lock brake system) of a passenger vehicle using a controllable piezo valve modulator. The ABS is designed to optimize for braking effectiveness and good steerability. As a first step, the principal design parameters of the piezo valve and pressure modulator are appropriately determined by considering the braking pressure variation during the ABS operation. The proposed piezo valve consists of a flapper, pneumatic circuit and a piezostack actuator. In order to get wide control range of the pressure, the pressure modulator is desired. The modulator consists of a dual-type cylinder filled with different substances (fluid and gas) and a piston rod moving vertical axis to transmit the force. Subsequently, a quarter car wheel slip model is formulated and integrated with the governing equation of the piezo valve modulator. A sliding mode controller to achieve the desired slip rate is then designed and implemented. Braking control performances such as brake pressure and slip rate are evaluated via computer simulations.

  18. Obstructive Sleep Apnea Screening Using a Piezo-Electric Sensor.

    Science.gov (United States)

    Erdenebayar, Urtnasan; Park, Jong Uk; Jeong, Pilsoo; Lee, Kyoung Joung

    2017-06-01

    In this study, we propose a novel method for obstructive sleep apnea (OSA) detection using a piezo-electric sensor. OSA is a relatively common sleep disorder. However, more than 80% of OSA patients remain undiagnosed. We investigated the feasibility of OSA assessment using a single-channel physiological signal to simplify the OSA screening. We detected both snoring and heartbeat information by using a piezo-electric sensor, and snoring index (SI) and features based on pulse rate variability (PRV) analysis were extracted from the filtered piezo-electric sensor signal. A support vector machine (SVM) was used as a classifier to detect OSA events. The performance of the proposed method was evaluated on 45 patients from mild, moderate, and severe OSA groups. The method achieved a mean sensitivity, specificity, and accuracy of 72.5%, 74.2%, and 71.5%; 85.8%, 80.5%, and 80.0%; and 70.3%, 77.1%, and 71.9% for the mild, moderate, and severe groups, respectively. Finally, these results not only show the feasibility of OSA detection using a piezo-electric sensor, but also illustrate its usefulness for monitoring sleep and diagnosing OSA. © 2017 The Korean Academy of Medical Sciences.

  19. Method and Apparatus for High-Permeability Magnetostrictive/Piezo-Fiber Laminates Having Colossal, Near-Ideal Magnetoelectricity

    OpenAIRE

    2007-01-01

    An ME composite laminate of at least one (1-3) piezo-fiber layer coupled with high-permeability alloy magnetostrictive layers, optionally formed of FeBSiC or equivalent. The composite laminate alternates the (1-3) piezo-fiber and high-permeability alloy magnetostrictive layers in a stacked manner. Optionally, the magnetization direction of the high-permeability alloy magnetostrictive layers and polarization direction of the piezo-fiber layer are an (L-L) arrangement. Optionally, thin film pol...

  20. Miniature piezo electric vacuum inlet valve

    Science.gov (United States)

    Keville, Robert F.; Dietrich, Daniel D.

    1998-03-24

    A miniature piezo electric vacuum inlet valve having a fast pulse rate and is battery operated with variable flow capability. The low power (piezo electric valves which require preloading of the crystal drive mechanism and 120 Vac, thus the valve of the present invention is smaller by a factor of three.

  1. Mechanosensitive Channels: In Touch with Piezo

    OpenAIRE

    Xiao, Rui; Xu, X.Z. Shawn

    2010-01-01

    Mechanosensory transduction underlies touch, hearing and proprioception and requires mechanosensitive channels that are directly gated by forces; however, the molecular identities of these channels remain largely elusive. A new study has identified Piezo1 and Piezo2 as a novel class of mechanosensitive channels.

  2. Piezo Voltage Controlled Planar Hall Effect Devices.

    Science.gov (United States)

    Zhang, Bao; Meng, Kang-Kang; Yang, Mei-Yin; Edmonds, K W; Zhang, Hao; Cai, Kai-Ming; Sheng, Yu; Zhang, Nan; Ji, Yang; Zhao, Jian-Hua; Zheng, Hou-Zhi; Wang, Kai-You

    2016-06-22

    The electrical control of the magnetization switching in ferromagnets is highly desired for future spintronic applications. Here we report on hybrid piezoelectric (PZT)/ferromagnetic (Co2FeAl) devices in which the planar Hall voltage in the ferromagnetic layer is tuned solely by piezo voltages. The change of planar Hall voltage is associated with magnetization switching through 90° in the plane under piezo voltages. Room temperature magnetic NOT and NOR gates are demonstrated based on the piezo voltage controlled Co2FeAl planar Hall effect devices without the external magnetic field. Our demonstration may lead to the realization of both information storage and processing using ferromagnetic materials.

  3. Synergy between Piezo1 and Piezo2 channels confers high-strain mechanosensitivity to articular cartilage

    Science.gov (United States)

    Lee, Whasil; Leddy, Holly A.; Chen, Yong; Lee, Suk Hee; Zelenski, Nicole A.; McNulty, Amy L.; Wu, Jason; Beicker, Kellie N.; Coles, Jeffrey; Zauscher, Stefan; Grandl, Jörg; Sachs, Frederick; Liedtke, Wolfgang B.

    2014-01-01

    Diarthrodial joints are essential for load bearing and locomotion. Physiologically, articular cartilage sustains millions of cycles of mechanical loading. Chondrocytes, the cells in cartilage, regulate their metabolic activities in response to mechanical loading. Pathological mechanical stress can lead to maladaptive cellular responses and subsequent cartilage degeneration. We sought to deconstruct chondrocyte mechanotransduction by identifying mechanosensitive ion channels functioning at injurious levels of strain. We detected robust expression of the recently identified mechanosensitive channels, PIEZO1 and PIEZO2. Combined directed expression of Piezo1 and -2 sustained potentiated mechanically induced Ca2+ signals and electrical currents compared with single-Piezo expression. In primary articular chondrocytes, mechanically evoked Ca2+ transients produced by atomic force microscopy were inhibited by GsMTx4, a PIEZO-blocking peptide, and by Piezo1- or Piezo2-specific siRNA. We complemented the cellular approach with an explant-cartilage injury model. GsMTx4 reduced chondrocyte death after mechanical injury, suggesting a possible therapy for reducing cartilage injury and posttraumatic osteoarthritis by attenuating Piezo-mediated cartilage mechanotransduction of injurious strains. PMID:25385580

  4. High-power piezo drive amplifier for large stack and PFC applications

    Science.gov (United States)

    Clingman, Dan J.; Gamble, Mike

    2001-08-01

    This paper describes the continuing development of Boeing High Power Piezo Drive Amplifiers. Described is the development and testing of a 1500 Vpp, 8 amp switching amplifier. This amplifier is used to drive a piezo stack driven rotor blade trailing edge flap on a full size helicopter. Also discuss is a switching amplifier designed to drive a Piezo Fiber Composite (PFC) active twist rotor blade. This amplifier was designed to drive the PFC material at 2000 Vpp and 0.5 amps. These amplifiers recycle reactive energy, allowing for a power and weight efficient amplifier design. This work was done in conjunction with the DARPA sponsored Phase II Smart Rotor Blade program and the NASA Langley Research Center sponsored Active Twist Rotor (ATR) blade program.

  5. Mechanism of piezo - and pyroelectricity of poly (vinylidene fluoride) electret

    International Nuclear Information System (INIS)

    Wada, Y.

    1980-01-01

    Basic concepts of the piezo - and pyroelectricity theory of polymer electrets are given. The origins of these effects are presented. The piezo - and pyroelectric constants are numerically obtained. (L.C.) [pt

  6. Mechanosensitive Piezo Channels in the Gastrointestinal Tract.

    Science.gov (United States)

    Alcaino, C; Farrugia, G; Beyder, A

    2017-01-01

    Sensation of mechanical forces is critical for normal function of the gastrointestinal (GI) tract and abnormalities in mechanosensation are linked to GI pathologies. In the GI tract there are several mechanosensitive cell types-epithelial enterochromaffin cells, intrinsic and extrinsic enteric neurons, smooth muscle cells and interstitial cells of Cajal. These cells use mechanosensitive ion channels that respond to mechanical forces by altering transmembrane ionic currents in a process called mechanoelectrical coupling. Several mechanosensitive ionic conductances have been identified in the mechanosensory GI cells, ranging from mechanosensitive voltage-gated sodium and calcium channels to the mechanogated ion channels, such as the two-pore domain potassium channels K2P (TREK-1) and nonselective cation channels from the transient receptor potential family. The recently discovered Piezo channels are increasingly recognized as significant contributors to cellular mechanosensitivity. Piezo1 and Piezo2 are nonselective cationic ion channels that are directly activated by mechanical forces and have well-defined biophysical and pharmacologic properties. The role of Piezo channels in the GI epithelium is currently under investigation and their role in the smooth muscle syncytium and enteric neurons is still not known. In this review, we outline the current state of knowledge on mechanosensitive ion channels in the GI tract, with a focus on the known and potential functions of the Piezo channels. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. High-Performance Composite Chocolate

    Science.gov (United States)

    Dean, Julian; Thomson, Katrin; Hollands, Lisa; Bates, Joanna; Carter, Melvyn; Freeman, Colin; Kapranos, Plato; Goodall, Russell

    2013-01-01

    The performance of any engineering component depends on and is limited by the properties of the material from which it is fabricated. It is crucial for engineering students to understand these material properties, interpret them and select the right material for the right application. In this paper we present a new method to engage students with…

  8. Aerodynamic Performance and Particle Image Velocimetery of Piezo Actuated Biomimetic Manduca Sexta Engineered Wings Towards the Design and Application of a Flapping Wing Flight Vehicle

    Science.gov (United States)

    2013-12-01

    elucidated the complexity and convoluted interrelation between insect musculature, body composition, wing design, operating Reynolds number, wing flap geometry...Figure 2.23 shows the AFIT FWMAV components after the laminated carbon fiber sheets are cut on the laser and ready for assembly. (a) Structure (b...Linkage (c) Passive rotation joint (d) Rotation stop (e) Alignment clips (f) Wing Figure 2.23: AFIT FWMAV cut-out laminated carbon fiber assembly parts. The

  9. A Microfluidic Approach for Studying Piezo Channels.

    Science.gov (United States)

    Maneshi, M M; Gottlieb, P A; Hua, S Z

    2017-01-01

    Microfluidics is an interdisciplinary field intersecting many areas in engineering. Utilizing a combination of physics, chemistry, biology, and biotechnology, along with practical applications for designing devices that use low volumes of fluids to achieve high-throughput screening, is a major goal in microfluidics. Microfluidic approaches allow the study of cells growth and differentiation using a variety of conditions including control of fluid flow that generates shear stress. Recently, Piezo1 channels were shown to respond to fluid shear stress and are crucial for vascular development. This channel is ideal for studying fluid shear stress applied to cells using microfluidic devices. We have developed an approach that allows us to analyze the role of Piezo channels on any given cell and serves as a high-throughput screen for drug discovery. We show that this approach can provide detailed information about the inhibitors of Piezo channels. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. Ultrasonic guided wave sensing characteristics of large area thin piezo coating

    Science.gov (United States)

    Rathod, V. T.; Jeyaseelan, A. Antony; Dutta, Soma; Mahapatra, D. Roy

    2017-10-01

    This paper reports on the characterization method and performance enhancement of thin piezo coating for ultrasonic guided wave sensing applications. We deposited the coatings by an in situ slurry coating method and studied their guided wave sensing properties on a one-dimensional metallic beam as a substrate waveguide. The developed piezo coatings show good sensitivity to the longitudinal and flexural modes of guided waves. Sensing voltage due to the guided waves at various different ultrasonic frequencies shows a linear dependence on the thickness of the coating. The coatings also exhibit linear sensor output voltage with respect to the induced dynamic strain magnitude. Diameter/size of the piezo coatings strongly influences the voltage response in relation to the wavelength. The proposed method used a characterization set-up involving coated sensors, reference transducers and an analytical model to estimate the piezoelectric coefficient of the piezo coating. The method eliminates the size dependent effect on the piezo property accurately and gives further insight to design better sensors/filters with respect to frequency/wavelength of interest. The developed coatings will have interesting applications in structural health monitoring (SHM) and internet of things (IOT).

  11. Piezo-electric automatic vehicle classification system : Oregon Department of Transportation with Castle Rock Consultants for a SHRP Long Term Pavement Performance Site.

    Science.gov (United States)

    1990-05-01

    Oregon has twelve sites that are part of the Strategic Highway Research Program (SHRP), Long Term Pavement Performance (LTPP) studies. Part of the data gathering on these sites involves vehicle weight and classification. This pilot project was to hel...

  12. Piezo-electric automatic vehicle classification system : Oregon Department of Transportation with Castle Rock Consultants for a SHRP Long Term Pavement Performance Site : final report.

    Science.gov (United States)

    1991-07-01

    Oregon has twelve pavement test sites that are part of the Strategic Highway Research Program (SHRP), Long Term Pavement Performance (LTPP) studies. Part of the data gathering on these sites involves vehicle weight and classification. This pilot proj...

  13. Mechanical study of the Saclay piezo tuner PTS (piezo tuning system) Care-SRF-WP8

    International Nuclear Information System (INIS)

    Bosland, P.; Wu, B.

    2005-03-01

    The present tuner is working inside Tesla test facility's cryo-modules without any piezo actuator. Thus the Lorentz force detuning in the pulsed mode of the accelerator is limiting the maximum accelerating field of cavity at about 25 MV/m. Previous studies and tests have demonstrated that the integration of piezo actuators in the tuner can lead to the compensation of the Lorentz force detuning at field higher than 35 MV/m. Our goal is now to develop and optimize a new tuner integrating piezo actuators. The mechanical studies are now finished and fabrication is in progress. This report presents the principle of this new system, its design and reviews the cavity frequency shifts during preparation process and assesses the forces applied by the cavity on the piezo actuators. (A.C.)

  14. Natural Composites: Cellulose Fibres and the related Performance of Composites

    DEFF Research Database (Denmark)

    Lilholt, Hans; Madsen, Bo

    2014-01-01

    Biobased materials are becoming of increasing interest as potential structural materials for the future. A useful concept in this context is the fibre reinforcement of materials by stiff and strong fibres. The biobased resources can contribute with cellulose fibres and biopolymers. This offers th...... in stiffness, on the packing ability of cellulose fibres and the related maximum fibre volume fraction in composites, on the moisture sorption of cellulose fibres and the related mass increase and (large) hygral strains induced, and on the mechanical performance of composites....

  15. Improved Photoresponse Performance of Self-Powered ZnO/Spiro-MeOTAD Heterojunction Ultraviolet Photodetector by Piezo-Phototronic Effect.

    Science.gov (United States)

    Shen, Yanwei; Yan, Xiaoqin; Si, Haonan; Lin, Pei; Liu, Yichong; Sun, Yihui; Zhang, Yue

    2016-03-09

    Strain-induced piezoelectric potential (piezopotential) within wurtzite-structured ZnO can engineer the energy-band structure at a contact or a junction and, thus, enhance the performance of corresponding optoelectronic devices by effectively tuning the charge carriers' separation and transport. Here, we report the fabrication of a flexible self-powered ZnO/Spiro-MeOTAD hybrid heterojunction ultraviolet photodetector (UV PD). The obtained device has a fast and stable response to the UV light illumination at zero bias. Together with responsivity and detectivity, the photocurrent can be increased about 1-fold upon applying a 0.753% tensile strain. The enhanced performance can be attributed to more efficient separation and transport of photogenerated electron-hole pairs, which is favored by the positive piezopotential modulated energy-band structure at the ZnO-Spiro-MeOTAD interface. This study demonstrates a promising approach to optimize the performance of a photodetector made of piezoelectric semiconductor materials through straining.

  16. Bubbles in piezo-acoustic inkjet printing

    NARCIS (Netherlands)

    Lohse, D.; Jeurissen, R.J.M.; de Jong, J.; Versluis, M.; Wijshoff, H.M.A.; van den Berg, M.; Reinten, H.

    2008-01-01

    Ink-jet printing is considered as the hitherto most successful application of microfluidics. A notorious problem in piezo-acoustic ink-jet systems is the formation of air bubbles during operation. They seriously disturb the acoustics and can cause the droplet formation to stop. We could show by a

  17. Improving the accuracy of walking piezo motors.

    Science.gov (United States)

    den Heijer, M; Fokkema, V; Saedi, A; Schakel, P; Rost, M J

    2014-05-01

    Many application areas require ultraprecise, stiff, and compact actuator systems with a high positioning resolution in combination with a large range as well as a high holding and pushing force. One promising solution to meet these conflicting requirements is a walking piezo motor that works with two pairs of piezo elements such that the movement is taken over by one pair, once the other pair reaches its maximum travel distance. A resolution in the pm-range can be achieved, if operating the motor within the travel range of one piezo pair. However, applying the typical walking drive signals, we measure jumps in the displacement up to 2.4 μm, when the movement is given over from one piezo pair to the other. We analyze the reason for these large jumps and propose improved drive signals. The implementation of our new drive signals reduces the jumps to less than 42 nm and makes the motor ideally suitable to operate as a coarse approach motor in an ultra-high vacuum scanning tunneling microscope. The rigidity of the motor is reflected in its high pushing force of 6.4 N.

  18. A piezo-bar pressure probe

    Science.gov (United States)

    Friend, W. H.; Murphy, C. L.; Shanfield, I.

    1967-01-01

    Piezo-bar pressure type probe measures the impact velocity or pressure of a moving debris cloud. It measures pressures up to 200,000 psi and peak pressures may be recorded with a total pulse duration between 5 and 65 musec.

  19. Piezo pump and pressurized circuit provided therewith

    NARCIS (Netherlands)

    Van Es, Johannes; Wits, Wessel Willems

    2015-01-01

    A piezo pump for use in a pressurized circuit includes a pump chamber with an inlet provided with a one way inlet valve, for connection to a feeding line of the pressurized circuit and an outlet provided with a one way outlet valve, for connection to a discharge line of the pressurized circuit and a

  20. Aerodynamic performance and particle image velocimetery of piezo actuated biomimetic manduca sexta engineered wings towards the design and application of a flapping wing flight vehicle

    Science.gov (United States)

    DeLuca, Anthony M.

    Considerable research and investigation has been conducted on the aerodynamic performance, and the predominate flow physics of the Manduca Sexta size of biomimetically designed and fabricated wings as part of the AFIT FWMAV design project. Despite a burgeoning interest and research into the diverse field of flapping wing flight and biomimicry, the aerodynamics of flapping wing flight remains a nebulous field of science with considerable variance into the theoretical abstractions surrounding aerodynamic mechanisms responsible for aerial performance. Traditional FWMAV flight models assume a form of a quasi-steady approximation of wing aerodynamics based on an infinite wing blade element model (BEM). An accurate estimation of the lift, drag, and side force coefficients is a critical component of autonomous stability and control models. This research focused on two separate experimental avenues into the aerodynamics of AFIT's engineered hawkmoth wings|forces and flow visualization. 1. Six degree of freedom force balance testing, and high speed video analysis was conducted on 30°, 45°, and 60° angle stop wings. A novel, non-intrusive optical tracking algorithm was developed utilizing a combination of a Gaussian Mixture Model (GMM) and ComputerVision (OpenCV) tools to track the wing in motion from multiple cameras. A complete mapping of the wing's kinematic angles as a function of driving amplitude was performed. The stroke angle, elevation angle, and angle of attack were tabulated for all three wings at driving amplitudes ranging from A=0.3 to A=0.6. The wing kinematics together with the force balance data was used to develop several aerodynamic force coefficient models. A combined translational and rotational aerodynamic model predicted lift forces within 10%, and vertical forces within 6%. The total power consumption was calculated for each of the three wings, and a Figure of Merit was calculated for each wing as a general expression of the overall efficiency of

  1. High performance nano-composite technology development

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Whung Whoe; Rhee, C. K.; Kim, S. J.; Park, S. D. [KAERI, Taejon (Korea, Republic of); Kim, E. K.; Jung, S. Y.; Ryu, H. J. [KRICT, Taejon (Korea, Republic of); Hwang, S. S.; Kim, J. K.; Hong, S. M. [KIST, Taejon (Korea, Republic of); Chea, Y. B. [KIGAM, Taejon (Korea, Republic of); Choi, C. H.; Kim, S. D. [ATS, Taejon (Korea, Republic of); Cho, B. G.; Lee, S. H. [HGREC, Taejon (Korea, Republic of)

    1999-06-15

    The trend of new material development are being to carried out not only high performance but also environmental attraction. Especially nano composite material which enhances the functional properties of components, extending the component life resulting to reduced the wastes and environmental contamination, has a great effect on various industrial area. The application of nano composite, depends on the polymer matrix and filler materials, has various application from semiconductor to medical field. In spite of nano composite merits, nano composite study are confined to a few special materials as a lab, scale because a few technical difficulties are still on hold. Therefore, the purpose of this study establishes the systematical planning to carried out the next generation projects on order to compete with other countries and overcome the protective policy of advanced countries with grasping over sea's development trends and our present status. (author).

  2. High temperature performance of polymer composites

    CERN Document Server

    Keller, Thomas

    2014-01-01

    The authors explain the changes in the thermophysical and thermomechanical properties of polymer composites under elevated temperatures and fire conditions. Using microscale physical and chemical concepts they allow researchers to find reliable solutions to their engineering needs on the macroscale. In a unique combination of experimental results and quantitative models, a framework is developed to realistically predict the behavior of a variety of polymer composite materials over a wide range of thermal and mechanical loads. In addition, the authors treat extreme fire scenarios up to more than 1000°C for two hours, presenting heat-protection methods to improve the fire resistance of composite materials and full-scale structural members, and discuss their performance after fire exposure. Thanks to the microscopic approach, the developed models are valid for a variety of polymer composites and structural members, making this work applicable to a wide audience, including materials scientists, polymer chemist...

  3. High performance nano-composite technology development

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Whung Whoe; Rhee, C. K.; Kim, S. J.; Park, S. D. [KAERI, Taejon (Korea, Republic of); Kim, E. K.; Jung, S. Y.; Ryu, H. J. [KRICT, Taejon (Korea, Republic of); Hwang, S. S.; Kim, J. K.; Hong, S. M. [KIST, Taejon (Korea, Republic of); Chea, Y. B. [KIGAM, Taejon (Korea, Republic of); Choi, C. H.; Kim, S. D. [ATS, Taejon (Korea, Republic of); Cho, B. G.; Lee, S. H. [HGREC, Taejon (Korea, Republic of)

    1999-06-15

    The trend of new material development are being to carried out not only high performance but also environmental attraction. Especially nano composite material which enhances the functional properties of components, extending the component life resulting to reduced the wastes and environmental contamination, has a great effect on various industrial area. The application of nano composite, depends on the polymer matrix and filler materials, has various application from semiconductor to medical field. In spite of nano composite merits, nano composite study are confined to a few special materials as a lab, scale because a few technical difficulties are still on hold. Therefore, the purpose of this study establishes the systematical planning to carried out the next generation projects on order to compete with other countries and overcome the protective policy of advanced countries with grasping over sea's development trends and our present status. (author).

  4. High performance nano-composite technology development

    International Nuclear Information System (INIS)

    Kim, Whung Whoe; Rhee, C. K.; Kim, S. J.; Park, S. D.; Kim, E. K.; Jung, S. Y.; Ryu, H. J.; Hwang, S. S.; Kim, J. K.; Hong, S. M.; Chea, Y. B.; Choi, C. H.; Kim, S. D.; Cho, B. G.; Lee, S. H.

    1999-06-01

    The trend of new material development are being to carried out not only high performance but also environmental attraction. Especially nano composite material which enhances the functional properties of components, extending the component life resulting to reduced the wastes and environmental contamination, has a great effect on various industrial area. The application of nano composite, depends on the polymer matrix and filler materials, has various application from semiconductor to medical field. In spite of nano composite merits, nano composite study are confined to a few special materials as a lab, scale because a few technical difficulties are still on hold. Therefore, the purpose of this study establishes the systematical planning to carried out the next generation projects on order to compete with other countries and overcome the protective policy of advanced countries with grasping over sea's development trends and our present status. (author).

  5. Piezo1 regulates mechanotransductive release of ATP from human RBCs.

    Science.gov (United States)

    Cinar, Eyup; Zhou, Sitong; DeCourcey, James; Wang, Yixuan; Waugh, Richard E; Wan, Jiandi

    2015-09-22

    Piezo proteins (Piezo1 and Piezo2) are recently identified mechanically activated cation channels in eukaryotic cells and associated with physiological responses to touch, pressure, and stretch. In particular, human RBCs express Piezo1 on their membranes, and mutations of Piezo1 have been linked to hereditary xerocytosis. To date, however, physiological functions of Piezo1 on normal RBCs remain poorly understood. Here, we show that Piezo1 regulates mechanotransductive release of ATP from human RBCs by controlling the shear-induced calcium (Ca(2+)) influx. We find that, in human RBCs treated with Piezo1 inhibitors or having mutant Piezo1 channels, the amounts of shear-induced ATP release and Ca(2+) influx decrease significantly. Remarkably, a critical extracellular Ca(2+) concentration is required to trigger significant ATP release, but membrane-associated ATP pools in RBCs also contribute to the release of ATP. Our results show how Piezo1 channels are likely to function in normal RBCs and suggest a previously unidentified mechanotransductive pathway in ATP release. Thus, we anticipate that the study will impact broadly on the research of red cells, cellular mechanosensing, and clinical studies related to red cell disorders and vascular disease.

  6. Voltage gating of mechanosensitive PIEZO channels.

    Science.gov (United States)

    Moroni, Mirko; Servin-Vences, M Rocio; Fleischer, Raluca; Sánchez-Carranza, Oscar; Lewin, Gary R

    2018-03-15

    Mechanosensitive PIEZO ion channels are evolutionarily conserved proteins whose presence is critical for normal physiology in multicellular organisms. Here we show that, in addition to mechanical stimuli, PIEZO channels are also powerfully modulated by voltage and can even switch to a purely voltage-gated mode. Mutations that cause human diseases, such as xerocytosis, profoundly shift voltage sensitivity of PIEZO1 channels toward the resting membrane potential and strongly promote voltage gating. Voltage modulation may be explained by the presence of an inactivation gate in the pore, the opening of which is promoted by outward permeation. Older invertebrate (fly) and vertebrate (fish) PIEZO proteins are also voltage sensitive, but voltage gating is a much more prominent feature of these older channels. We propose that the voltage sensitivity of PIEZO channels is a deep property co-opted to add a regulatory mechanism for PIEZO activation in widely different cellular contexts.

  7. A self-adaption compensation control for hysteresis nonlinearity in piezo-actuated stages based on Pi-sigma fuzzy neural network

    Science.gov (United States)

    Xu, Rui; Zhou, Miaolei

    2018-04-01

    Piezo-actuated stages are widely applied in the high-precision positioning field nowadays. However, the inherent hysteresis nonlinearity in piezo-actuated stages greatly deteriorates the positioning accuracy of piezo-actuated stages. This paper first utilizes a nonlinear autoregressive moving average with exogenous inputs (NARMAX) model based on the Pi-sigma fuzzy neural network (PSFNN) to construct an online rate-dependent hysteresis model for describing the hysteresis nonlinearity in piezo-actuated stages. In order to improve the convergence rate of PSFNN and modeling precision, we adopt the gradient descent algorithm featuring three different learning factors to update the model parameters. The convergence of the NARMAX model based on the PSFNN is analyzed effectively. To ensure that the parameters can converge to the true values, the persistent excitation condition is considered. Then, a self-adaption compensation controller is designed for eliminating the hysteresis nonlinearity in piezo-actuated stages. A merit of the proposed controller is that it can directly eliminate the complex hysteresis nonlinearity in piezo-actuated stages without any inverse dynamic models. To demonstrate the effectiveness of the proposed model and control methods, a set of comparative experiments are performed on piezo-actuated stages. Experimental results show that the proposed modeling and control methods have excellent performance.

  8. High Performance Graphene Oxide Based Rubber Composites

    Science.gov (United States)

    Mao, Yingyan; Wen, Shipeng; Chen, Yulong; Zhang, Fazhong; Panine, Pierre; Chan, Tung W.; Zhang, Liqun; Liang, Yongri; Liu, Li

    2013-01-01

    In this paper, graphene oxide/styrene-butadiene rubber (GO/SBR) composites with complete exfoliation of GO sheets were prepared by aqueous-phase mixing of GO colloid with SBR latex and a small loading of butadiene-styrene-vinyl-pyridine rubber (VPR) latex, followed by their co-coagulation. During co-coagulation, VPR not only plays a key role in the prevention of aggregation of GO sheets but also acts as an interface-bridge between GO and SBR. The results demonstrated that the mechanical properties of the GO/SBR composite with 2.0 vol.% GO is comparable with those of the SBR composite reinforced with 13.1 vol.% of carbon black (CB), with a low mass density and a good gas barrier ability to boot. The present work also showed that GO-silica/SBR composite exhibited outstanding wear resistance and low-rolling resistance which make GO-silica/SBR very competitive for the green tire application, opening up enormous opportunities to prepare high performance rubber composites for future engineering applications. PMID:23974435

  9. A protein interaction mechanism for suppressing the mechanosensitive Piezo channels

    OpenAIRE

    Zhang, Tingxin; Chi, Shaopeng; Jiang, Fan; Zhao, Qiancheng; Xiao, Bailong

    2017-01-01

    Piezo proteins are bona fide mammalian mechanotransduction channels for various cell types including endothelial cells. The mouse Piezo1 of 2547 residues forms a three-bladed, propeller-like homo-trimer comprising a central pore-module and three propeller-structures that might serve as mechanotransduction-modules. However, the mechanogating and regulation of Piezo channels remain unclear. Here we identify the sarcoplasmic /endoplasmic-reticulum Ca2+ ATPase (SERCA), including the widely expres...

  10. Study of a Piezo-Thermo-Elastic Materials Console

    Directory of Open Access Journals (Sweden)

    hamza madjid berrabah

    2015-09-01

    Full Text Available In the first part of this work, analytical expressions were determined for the stresses through the thickness of a composite beam submitted to electrical excitation. In the second part of this study we are interested in the theory of elasticity, which is used to obtain exact solutions of piezo-thermo-elastic consoles gradually coupled evaluated under different loads. These solutions are used to identify the piezoelectric parameter and thermal coefficients of the materials. In addition, numerical results are obtained for the analysis of the loaded console by two different types of loading. In this study we show also that changing the linear thermal parameters of the material does not affect the distribution of the stress and the induction of the beam. However it affetcs the components of the deformation, electric field, the displacement and the electric potential of the console.

  11. A protein interaction mechanism for suppressing the mechanosensitive Piezo channels.

    Science.gov (United States)

    Zhang, Tingxin; Chi, Shaopeng; Jiang, Fan; Zhao, Qiancheng; Xiao, Bailong

    2017-11-27

    Piezo proteins are bona fide mammalian mechanotransduction channels for various cell types including endothelial cells. The mouse Piezo1 of 2547 residues forms a three-bladed, propeller-like homo-trimer comprising a central pore-module and three propeller-structures that might serve as mechanotransduction-modules. However, the mechanogating and regulation of Piezo channels remain unclear. Here we identify the sarcoplasmic /endoplasmic-reticulum Ca 2+ ATPase (SERCA), including the widely expressed SERCA2, as Piezo interacting proteins. SERCA2 strategically suppresses Piezo1 via acting on a 14-residue-constituted intracellular linker connecting the pore-module and mechanotransduction-module. Mutating the linker impairs mechanogating and SERCA2-mediated modulation of Piezo1. Furthermore, the synthetic linker-peptide disrupts the modulatory effects of SERCA2, demonstrating the key role of the linker in mechanogating and regulation. Importantly, the SERCA2-mediated regulation affects Piezo1-dependent migration of endothelial cells. Collectively, we identify SERCA-mediated regulation of Piezos and the functional significance of the linker, providing important insights into the mechanogating and regulation mechanisms of Piezo channels.

  12. A study on the performance of piezoelectric composite materials for designing embedded transducers for concrete assessment

    Science.gov (United States)

    Dumoulin, Cédric; Deraemaeker, Arnaud

    2018-03-01

    Ultrasonic measurements of concrete can provide crucial information about its state of health. The most common practice in the construction industry consists in using external probes which strongly limits the use of the method since large parts of the in-service structures are difficult to access. It is also possible to assess in real time the setting process of the concrete using ultrasonic measurements. In practice, the field measurement of the concrete hardening is limited by the formworks. As an alternative, some research teams have studied the possibility to directly embed the transducers into the concrete structures. The current embedded ultrasonic transducers are of two categories: bulk piezoelectric elements surrounded by several coating and matching layers and composites piezoelectric elements. Both technologies aim at optimizing the wave energy transmitted to the tested medium. The performances of the transducers of the first kind have been studied in a previous study. A fair amount of recent research has been focused on the development of novel cement-based piezoelectric composites. In this study, we first compare the effective properties of such cement-based materials with more widespread composites made with matrices of epoxy resins or polyurethane. The study only concerns the 1-3 fiber arrangement composites. The effective properties are computed using both an analytical mixing rule method and a finite element based homogenization method using representative volume elements (RVEs) which allows for considering more realistic fiber arrangements, leading yet to very similar results. The effective piezoelectric properties of cement-based composites appear to be very low compared to composites made of epoxy or polyurethane. This result is underlined by looking at the acoustic response and the electric input impedance of different piezoelectric disks where we compare performances of such transducers with a low-cost bulk piezoelectric disc element. The first

  13. Mastication noise reduction method for fully implantable hearing aid using piezo-electric sensor.

    Science.gov (United States)

    Na, Sung Dae; Lee, Gihyoun; Wei, Qun; Seong, Ki Woong; Cho, Jin Ho; Kim, Myoung Nam

    2017-07-20

    Fully implantable hearing devices (FIHDs) can be affected by generated biomechanical noise such as mastication noise. To reduce the mastication noise using a piezo-electric sensor, the mastication noise is measured with the piezo-electric sensor, and noise reduction is practiced by the energy difference. For the experiment on mastication noise, a skull model was designed using artificial skull model and a piezo-electric sensor that can measure the vibration signals better than other sensors. A 1 kHz pure-tone sound through a standard speaker was applied to the model while the lower jawbone of the model was moved in a masticatory fashion. The correlation coefficients and signal-to-noise ratio (SNR) before and after application of the proposed method were compared. It was found that the signal-to-noise ratio and correlation coefficients increased by 4.48 dB and 0.45, respectively. The mastication noise is measured by piezo-electric sensor as the mastication noise that occurred during vibration. In addition, the noise was reduced by using the proposed method in conjunction with MATLAB. In order to confirm the performance of the proposed method, the correlation coefficients and signal-to-noise ratio before and after signal processing were calculated. In the future, an implantable microphone for real-time processing will be developed.

  14. Cell-Type-Specific Splicing of Piezo2 Regulates Mechanotransduction

    Directory of Open Access Journals (Sweden)

    Marcin Szczot

    2017-12-01

    Full Text Available Summary: Piezo2 is a mechanically activated ion channel required for touch discrimination, vibration detection, and proprioception. Here, we discovered that Piezo2 is extensively spliced, producing different Piezo2 isoforms with distinct properties. Sensory neurons from both mice and humans express a large repertoire of Piezo2 variants, whereas non-neuronal tissues express predominantly a single isoform. Notably, even within sensory ganglia, we demonstrate the splicing of Piezo2 to be cell type specific. Biophysical characterization revealed substantial differences in ion permeability, sensitivity to calcium modulation, and inactivation kinetics among Piezo2 splice variants. Together, our results describe, at the molecular level, a potential mechanism by which transduction is tuned, permitting the detection of a variety of mechanosensory stimuli. : Szczot et al. find that the mechanoreceptor Piezo2 is extensively alternatively spliced, generating multiple distinct isoforms. Their findings indicate that these splice products have specific tissue and cell type expression patterns and exhibit differences in receptor properties. Keywords: Piezo, touch, sensation, ion-channel, splicing

  15. Micro Coriolis mass flow sensor driven by external piezo ceramic

    NARCIS (Netherlands)

    Zeng, Yaxiang; Groenesteijn, Jarno; Alveringh, Dennis; Wiegerink, Remco J.; Lötters, Joost Conrad

    2017-01-01

    We have realized a micro Coriolis mass flow meter driven with an external piezo ceramic. The piezoelec tric ceramic is glued on top of sensor chip with a inertial weight on top of the piezo ceramic. Its ability to measure mass flow is characterized by a laser Doppler vibrometer. Our measurement with

  16. Patterned piezo-, pyro-, and ferroelectricity of poled polymer electrets

    International Nuclear Information System (INIS)

    Qiu, Xunlin

    2010-01-01

    Polymers with strong piezo-, pyro-, and ferroelectricity are attractive for a wide range of applications. In particular, semicrystalline ferroelectric polymers are suitable for a large variety of piezo- and pyroelectric transducers or sensors, while amorphous polymers containing chromophore molecules are particularly interesting for photonic devices. Recently, a new class of polymer materials has been added to this family: internally charged cellular space-charge polymer electrets (so-called “ferroelectrets”), whose piezoelectricity can be orders of magnitude higher than that of conventional ferroelectric polymers. Suitable patterning of these materials leads to improved or unusual macroscopic piezo-, pyro-, and ferroelectric or nonlinear optical properties that may be particularly useful for advanced transducer or waveguide applications. In the present paper, the piezo-, pyro-, and ferroelectricity of poled polymers is briefly introduced, an overview on the preparation of polymer electrets with patterned piezo-, pyro-, and ferroelectricity is provided and a survey of selected applications is presented.

  17. Control Software for Piezo Stepping Actuators

    Science.gov (United States)

    Shields, Joel F.

    2013-01-01

    A control system has been developed for the Space Interferometer Mission (SIM) piezo stepping actuator. Piezo stepping actuators are novel because they offer extreme dynamic range (centimeter stroke with nanometer resolution) with power, thermal, mass, and volume advantages over existing motorized actuation technology. These advantages come with the added benefit of greatly reduced complexity in the support electronics. The piezo stepping actuator consists of three fully redundant sets of piezoelectric transducers (PZTs), two sets of brake PZTs, and one set of extension PZTs. These PZTs are used to grasp and move a runner attached to the optic to be moved. By proper cycling of the two brake and extension PZTs, both forward and backward moves of the runner can be achieved. Each brake can be configured for either a power-on or power-off state. For SIM, the brakes and gate of the mechanism are configured in such a manner that, at the end of the step, the actuator is in a parked or power-off state. The control software uses asynchronous sampling of an optical encoder to monitor the position of the runner. These samples are timed to coincide with the end of the previous move, which may consist of a variable number of steps. This sampling technique linearizes the device by avoiding input saturation of the actuator and makes latencies of the plant vanish. The software also estimates, in real time, the scale factor of the device and a disturbance caused by cycling of the brakes. These estimates are used to actively cancel the brake disturbance. The control system also includes feedback and feedforward elements that regulate the position of the runner to a given reference position. Convergence time for smalland medium-sized reference positions (less than 200 microns) to within 10 nanometers can be achieved in under 10 seconds. Convergence times for large moves (greater than 1 millimeter) are limited by the step rate.

  18. New piezo driven gas inlet valve for fusion experiments

    International Nuclear Information System (INIS)

    Usselmann, E.; Hemmerich, J.L.; How, J.; Holland, D.; Orchard, J.; Winkel, T.; Schargitz, U.; Pocheim, N.

    1989-01-01

    The gas inlet valves used at the JET experiment are described and their performances are discussed. A new gas-valve development suitable to replace the existing valves at JET and for future use in large fusion experiments is presented. The new valve is equipped with a piezo-electric translator and has a dosing range of 0-800 mbarls -1 for D 2 . The operating mode of the valve is fail-safe closed with a leak-rate of ≤ 10 -9 mbarls -1 . The design, the test results and throughput values in dependence of filling pressure and control voltage are presented and experiences with the prototype valve as a new gas inlet valve for the JET operation are described

  19. Piezo-Phototronic Effect Enhanced Flexible Solar Cells Based on n-ZnO/p-SnS Core-Shell Nanowire Array.

    Science.gov (United States)

    Zhu, Laipan; Wang, Longfei; Xue, Fei; Chen, Libo; Fu, Jianqiang; Feng, Xiaolong; Li, Tianfeng; Wang, Zhong Lin

    2017-01-01

    The piezo-phototronic effect is about the enhanced separation, transport, and recombination of the photogenerated carriers using the piezoelectric polarization charges present in piezoelectric-semiconductor materials. Here, it is presented that the piezo-phototronic effect can be effectively applied to improve the relative conversion efficiency of a flexible solar cell based on n-ZnO/p-SnS core-shell nanowire array for 37.3% under a moderate vertical pressure. The performance of the solar cell can be effectively enhanced by a gentle bending of the device, showing its potential for application in curly geometries. This study not only adds further understanding about the concept of increasing solar energy conversion efficiency via piezo-phototronic effect, but also demonstrates the great potential of piezo-phototronic effect in the application of large-scale, flexible, and lightweight nanowire array solar cells.

  20. Piezo-earpiece for micro-power generation from ear canal dynamic motion

    International Nuclear Information System (INIS)

    Delnavaz, Aidin; Voix, Jérémie

    2013-01-01

    This paper focuses on improving the past performance of ear canal energy harvesting by developing a piezo-earpiece prototype and a multiphysics finite element method to integrate more complex and effective piezoelectric structures. The proposed handmade piezo-earpiece prototype is a custom-moulded soft earpiece wrapped in a layer of flexible polyvinylidene fluoride. A finite element model is developed in order to estimate the energy harvesting capability of the piezoelectric layer. A prototype of the energy harvester is fabricated and tested. The experimental results show that the proposed device is able to generate 44 μJ of energy corresponding to an average value of 70 μW per jaw opening and closing cycle. Simulation of energy harvesting based on the finite element method is validated by the experimental results, thus confirming it as a versatile tool to model, optimize and evaluate the performance of other types of flexible piezoelectric structures for in-ear energy harvesting applications. (paper)

  1. Piezo-optic surfaces of lithium niobate crystals

    International Nuclear Information System (INIS)

    Mytsyk, B. G.; Dem'yanyshyn, N. M.

    2006-01-01

    A method of construction of the spatial distribution of the piezo-optic effect in crystals is proposed. A particular case of this method is the known technique of construction of indicator surfaces of the piezo-optic effect. The essence of the proposed method consists in determining the difference in the radius vectors of the optical indicatrix perturbed by stress and the free optical indicatrix. It is shown that this difference in the radius vectors is mathematically identical to the law of transformation of the piezo-optic tensor during the rotation of the coordinate system

  2. Piezo proteins: regulators of mechanosensation and other cellular processes.

    Science.gov (United States)

    Bagriantsev, Sviatoslav N; Gracheva, Elena O; Gallagher, Patrick G

    2014-11-14

    Piezo proteins have recently been identified as ion channels mediating mechanosensory transduction in mammalian cells. Characterization of these channels has yielded important insights into mechanisms of somatosensation, as well as other mechano-associated biologic processes such as sensing of shear stress, particularly in the vasculature, and regulation of urine flow and bladder distention. Other roles for Piezo proteins have emerged, some unexpected, including participation in cellular development, volume regulation, cellular migration, proliferation, and elongation. Mutations in human Piezo proteins have been associated with a variety of disorders including hereditary xerocytosis and several syndromes with muscular contracture as a prominent feature. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  3. Piezo Proteins: Regulators of Mechanosensation and Other Cellular Processes*

    Science.gov (United States)

    Bagriantsev, Sviatoslav N.; Gracheva, Elena O.; Gallagher, Patrick G.

    2014-01-01

    Piezo proteins have recently been identified as ion channels mediating mechanosensory transduction in mammalian cells. Characterization of these channels has yielded important insights into mechanisms of somatosensation, as well as other mechano-associated biologic processes such as sensing of shear stress, particularly in the vasculature, and regulation of urine flow and bladder distention. Other roles for Piezo proteins have emerged, some unexpected, including participation in cellular development, volume regulation, cellular migration, proliferation, and elongation. Mutations in human Piezo proteins have been associated with a variety of disorders including hereditary xerocytosis and several syndromes with muscular contracture as a prominent feature. PMID:25305018

  4. Piezo-Phototronic Enhanced UV Sensing Based on a Nanowire Photodetector Array.

    Science.gov (United States)

    Han, Xun; Du, Weiming; Yu, Ruomeng; Pan, Caofeng; Wang, Zhong Lin

    2015-12-22

    A large array of Schottky UV photodetectors (PDs) based on vertical aligned ZnO nanowires is achieved. By introducing the piezo-phototronic effect, the performance of the PD array is enhanced up to seven times in photoreponsivity, six times in sensitivity, and 2.8 times in detection limit. The UV PD array may have applications in optoelectronic systems, adaptive optical computing, and communication. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. A study on nozzle flow and spray characteristics of piezo injector for next generation high response injection

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jin Wook [Korea Institue of Machinery and Materials, Daejeon (Korea, Republic of); Min, Kyoung Doug [Seoul National University, Seoul (Korea, Republic of)

    2006-06-15

    Most diesel injector, which is currently used in high-pressure common rail fuel injection system of diesel engine, is driven by the solenoid coil energy for its needle movement. The main disadvantage of this solenoid-driven injector is a high power consumption, high power loss through solenoid coil and relatively fixed needle response's problem. In this study, a prototype piezo-driven injector, as a new injector mechanism driven by piezoelectric energy based on the concept of inverse piezo-electric effect, has been designed and fabricated to know the effect of piezo-driven injection processes on the diesel spray structure and internal nozzle flow. Firstly we investigated the spray characteristics in a constant volume chamber pressurized by nitrogen gas using the back diffusion light illumination method for high-speed temporal photography and also analyzed the inside nozzle flow by a fully transient simulation with cavitation model using VOF(Volume Of Fraction) method. The numerical calculation has been performed to simulate the cavitating flow of 3-dimensional real size single hole nozzle along the injection duration. Results were compared between a conventional solenoid-driven injector and piezo-driven injector, both equipped with the same micro-sac multi-hole injection nozzle. The experimental results show that the piezo-driven injector has short injection delay and a faster spray development and produces higher injection velocity than the solenoid-driven injector. And the predicted simulation results with the degree of cavitation's generation inside nozzle for faster needle response in a piezo-driven injector were reflected to spray development in agreement with the experimental spray images.

  6. A study on nozzle flow and spray characteristics of piezo injector for next generation high response injection

    International Nuclear Information System (INIS)

    Lee, Jin Wook; Min, Kyoung Doug

    2006-01-01

    Most diesel injector, which is currently used in high-pressure common rail fuel injection system of diesel engine, is driven by the solenoid coil energy for its needle movement. The main disadvantage of this solenoid-driven injector is a high power consumption, high power loss through solenoid coil and relatively fixed needle response's problem. In this study, a prototype piezo-driven injector, as a new injector mechanism driven by piezoelectric energy based on the concept of inverse piezo-electric effect, has been designed and fabricated to know the effect of piezo-driven injection processes on the diesel spray structure and internal nozzle flow. Firstly we investigated the spray characteristics in a constant volume chamber pressurized by nitrogen gas using the back diffusion light illumination method for high-speed temporal photography and also analyzed the inside nozzle flow by a fully transient simulation with cavitation model using VOF(Volume Of Fraction) method. The numerical calculation has been performed to simulate the cavitating flow of 3-dimensional real size single hole nozzle along the injection duration. Results were compared between a conventional solenoid-driven injector and piezo-driven injector, both equipped with the same micro-sac multi-hole injection nozzle. The experimental results show that the piezo-driven injector has short injection delay and a faster spray development and produces higher injection velocity than the solenoid-driven injector. And the predicted simulation results with the degree of cavitation's generation inside nozzle for faster needle response in a piezo-driven injector were reflected to spray development in agreement with the experimental spray images

  7. Testing of Piezo-Actuated Glass Micro-Membranes by Optical Low-Coherence Reflectometry.

    Science.gov (United States)

    Merlo, Sabina; Poma, Paolo; Crisà, Eleonora; Faralli, Dino; Soldo, Marco

    2017-02-25

    In this work, we have applied optical low-coherence reflectometry (OLCR), implemented with infra-red light propagating in fiberoptic paths, to perform static and dynamic analyses on piezo-actuated glass micro-membranes. The actuator was fabricated by means of thin-film piezoelectric MEMS technology and was employed for modifying the micro-membrane curvature, in view of its application in micro-optic devices, such as variable focus micro-lenses. We are here showing that OLCR incorporating a near-infrared superluminescent light emitting diode as the read-out source is suitable for measuring various parameters such as the micro-membrane optical path-length, the membrane displacement as a function of the applied voltage (yielding the piezo-actuator hysteresis) as well as the resonance curve of the fundamental vibration mode. The use of an optical source with short coherence-time allows performing interferometric measurements without spurious resonance effects due to multiple parallel interfaces of highly planar slabs, furthermore selecting the plane/layer to be monitored. We demonstrate that the same compact and flexible setup can be successfully employed to perform spot optical measurements for static and dynamic characterization of piezo-MEMS in real time.

  8. Tunable band gaps in acoustic metamaterials with periodic arrays of resonant shunted piezos

    International Nuclear Information System (INIS)

    Chen Sheng-Bing; Wen Ji-Hong; Wang Gang; Wen Xi-Sen

    2013-01-01

    Periodic arrays of resonant shunted piezoelectric patches are employed to control the wave propagation in a two-dimensional (2D) acoustic metamaterial. The performance is characterized by the finite element method. More importantly, we propose an approach to solving the conventional issue of the nonlinear eigenvalue problem, and give a convenient solution to the dispersion properties of 2D metamaterials with periodic arrays of resonant shunts in this article. Based on this modeling method, the dispersion relations of a 2D metamaterial with periodic arrays of resonant shunted piezos are calculated. The results show that the internal resonances of the shunting system split the dispersion curves, thereby forming a locally resonant band gap. However, unlike the conventional locally resonant gap, the vibrations in this locally resonant gap are unable to be completely localized in oscillators consisting of shunting inductors and piezo-patches

  9. Role of Piezo Channels in Joint Health and Injury.

    Science.gov (United States)

    Lee, W; Guilak, F; Liedtke, W

    2017-01-01

    Cartilage is an intrinsically mechanically sensitive tissue composed of chondrocytes as the only cell type. Chondrocyte mechanotransduction is not well understood, but recently we identified critical components of the mechanotransduction machinery demonstrating how mechanical stimulation of these cells can be converted into cellular calcium signals. Physiologic mechanical cues induce anabolic responses of (post-mitotic) chondrocytes via transient receptor potential vanilloid 4 ion channels, whereas injurious mechanical stress is transduced by Piezo1 jointly with Piezo2 ion channels. This chapter sheds light on the latter discovery and provides a rationale for follow-up questions, such as the nature of interaction between Piezo1 and Piezo2, and their tethering to the cytoskeleton. These recent insights can be leveraged toward translational medical progress to benefit diagnosis and treatment of osteoarthritis, representing a large and growing unmet medical need in the United States and large parts of the world. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. High performance carbon–carbon composites

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    protected against oxidation either through matrix modification with Si, Zr, Hf etc. or by multilayer oxidation protection ... advanced composites for a wide range of applications. The majority of products still ... CVD is a very slow process and it takes months together to get dense carbon–carbon composites. Porous structures ...

  11. High performance carbon-carbon composites

    Indian Academy of Sciences (India)

    These composites are made of fibres in various directions and carbonaceous polymers and hydrocarbons as matrix precursors. Their density and properties depend on the type and volume fraction of reinforcement, matrix precursor used and end heat treatment temperature. Composites made with thermosetting resins as ...

  12. Piezo Proteins: Regulators of Mechanosensation and Other Cellular Processes*

    OpenAIRE

    Bagriantsev, Sviatoslav N.; Gracheva, Elena O.; Gallagher, Patrick G.

    2014-01-01

    Piezo proteins have recently been identified as ion channels mediating mechanosensory transduction in mammalian cells. Characterization of these channels has yielded important insights into mechanisms of somatosensation, as well as other mechano-associated biologic processes such as sensing of shear stress, particularly in the vasculature, and regulation of urine flow and bladder distention. Other roles for Piezo proteins have emerged, some unexpected, including participation in cellular deve...

  13. Characterization of a piezo bendable X-ray mirror.

    Science.gov (United States)

    Vannoni, Maurizio; Freijo Martín, Idoia; Siewert, Frank; Signorato, Riccardo; Yang, Fan; Sinn, Harald

    2016-01-01

    A full-scale piezo bendable mirror built as a prototype for an offset mirror at the European XFEL is characterized. The piezo ceramic elements are glued onto the mirror substrate, side-face on with respect to the reflecting surface. Using a nanometre optical component measuring machine and a large-aperture Fizeau interferometer, the mirror profile and influence functions were characterized, and further analysis was made to investigate the junction effect, hysteresis, twisting and reproducibility.

  14. A piezo-ring-on-chip microfluidic device for simple and low-cost mass spectrometry interfacing.

    Science.gov (United States)

    Tsao, Chia-Wen; Lei, I-Chao; Chen, Pi-Yu; Yang, Yu-Liang

    2018-02-12

    Mass spectrometry (MS) interfacing technology provides the means for incorporating microfluidic processing with post MS analysis. In this study, we propose a simple piezo-ring-on-chip microfluidic device for the controlled spraying of MALDI-MS targets. This device uses a low-cost, commercially-available ring-shaped piezoelectric acoustic atomizer (piezo-ring) directly integrated into a polydimethylsiloxane microfluidic device to spray the sample onto the MS target substrate. The piezo-ring-on-chip microfluidic device's design, fabrication, and actuation, and its pulsatile pumping effects were evaluated. The spraying performance was examined by depositing organic matrix samples onto the MS target substrate by using both an automatic linear motion motor, and manual deposition. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) was performed to analyze the peptide samples on the MALDI target substrates. Using our technique, model peptides with 10 -6 M concentration can be successfully detected. The results also indicate that the piezo-ring-on-chip approach forms finer matrix crystals and presents better MS signal uniformity with little sample consumption compared to the conventional pipetting method.

  15. Growth performance, body measurements, carcass composition and ...

    African Journals Online (AJOL)

    Gizzard percentage was significantly greater in males, and heart percentage was significantly greater in females. Due to their high bodyweight, good FCR, and favourable carcass composition, SM3 Heavy male ducks are more useful as broiler duck than females. Keywords: carcasses, digestive system, growth, Pekin duck, ...

  16. Lateral bending of tapered piezo-semiconductive nanostructures for ultra-sensitive mechanical force to voltage conversion.

    Science.gov (United States)

    Araneo, Rodolfo; Falconi, Christian

    2013-07-05

    Quasi-1D piezoelectric nanostructures may offer unprecedented sensitivity for transducing minuscule input mechanical forces into high output voltages due to both scaling laws and increased piezoelectric coefficients. However, until now both theoretical and experimental studies have suggested that, for a given mechanical force, lateral bending of piezoelectric nanowires results in lower output electric potentials than vertical compression. Here we demonstrate that this result only applies to nanostructures with a constant cross-section. Moreover, though it is commonly believed that the output electric potential of a strained piezo-semiconductive device can only be reduced by the presence of free charges, we show that the output piezopotential of laterally bent tapered nanostructures, with typical doping levels and very small input forces, can be even increased up to two times by free charges.Our analyses confirm that, though not optimal for piezoelectric energy harvesting, lateral bending of tapered nanostructures with typical doping levels can be ideal for transducing tiny input mechanical forces into high and accessible piezopotentials. Our results provide guidelines for designing high-performance piezo-nano-devices for energy harvesting, mechanical sensing, piezotronics, piezo-phototronics, and piezo-controlled chemical reactions, among others.

  17. Lateral bending of tapered piezo-semiconductive nanostructures for ultra-sensitive mechanical force to voltage conversion

    International Nuclear Information System (INIS)

    Araneo, Rodolfo; Falconi, Christian

    2013-01-01

    Quasi-1D piezoelectric nanostructures may offer unprecedented sensitivity for transducing minuscule input mechanical forces into high output voltages due to both scaling laws and increased piezoelectric coefficients. However, until now both theoretical and experimental studies have suggested that, for a given mechanical force, lateral bending of piezoelectric nanowires results in lower output electric potentials than vertical compression. Here we demonstrate that this result only applies to nanostructures with a constant cross-section. Moreover, though it is commonly believed that the output electric potential of a strained piezo-semiconductive device can only be reduced by the presence of free charges, we show that the output piezopotential of laterally bent tapered nanostructures, with typical doping levels and very small input forces, can be even increased up to two times by free charges. Our analyses confirm that, though not optimal for piezoelectric energy harvesting, lateral bending of tapered nanostructures with typical doping levels can be ideal for transducing tiny input mechanical forces into high and accessible piezopotentials. Our results provide guidelines for designing high-performance piezo-nano-devices for energy harvesting, mechanical sensing, piezotronics, piezo-phototronics, and piezo-controlled chemical reactions, among others. (paper)

  18. Harvesting vibrational energy due to intermodal systems via nano coated piezo electric devices.

    Science.gov (United States)

    2015-12-01

    Vibrational energy resulting from intermodal transport systems can be recovered through the use of energy harvesting system consisting of PZT piezo electric material as the primary energy harvesting component. The ability of traditional PZT piezo ele...

  19. Improving Turbine Performance with Ceramic Matrix Composites

    Science.gov (United States)

    DiCarlo, James A.

    2007-01-01

    Under the new NASA Fundamental Aeronautics Program, efforts are on-going within the Supersonics Project aimed at the implementation of advanced SiC/SiC ceramic composites into hot section components of future gas turbine engines. Due to recent NASA advancements in SiC-based fibers and matrices, these composites are lighter and capable of much higher service temperatures than current metallic superalloys, which in turn will allow the engines to operate at higher efficiencies and reduced emissions. This presentation briefly reviews studies within Task 6.3.3 that are primarily aimed at developing physics-based concepts, tools, and process/property models for micro- and macro-structural design, fabrication, and lifing of SiC/SiC turbine components in general and airfoils in particular. Particular emphasis is currently being placed on understanding and modeling (1) creep effects on residual stress development within the component, (2) fiber architecture effects on key composite properties such as design strength, and (3) preform formation processes so that the optimum architectures can be implemented into complex-shaped components, such as turbine vanes and blades.

  20. Ion Permeation and Mechanotransduction Mechanisms of Mechanosensitive Piezo Channels.

    Science.gov (United States)

    Zhao, Qiancheng; Wu, Kun; Geng, Jie; Chi, Shaopeng; Wang, Yanfeng; Zhi, Peng; Zhang, Mingmin; Xiao, Bailong

    2016-03-16

    Piezo proteins have been proposed as the long-sought-after mechanosensitive cation channels in mammals that play critical roles in various mechanotransduction processes. However, the molecular bases that underlie their ion permeation and mechanotransduction have remained functionally undefined. Here we report our finding of the miniature pore-forming module of Piezo1 that resembles the pore architecture of other trimeric channels and encodes the essential pore properties. We further identified specific residues within the pore module that determine unitary conductance, pore blockage and ion selectivity for divalent and monovalent cations and anions. The non-pore-containing region of Piezo1 confers mechanosensitivity to mechano-insensitive trimeric acid-sensing ion channels, demonstrating that Piezo1 channels possess intrinsic mechanotransduction modules separate from their pore modules. In conclusion, this is the first report on the bona fide pore module and mechanotransduction components of Piezo channels, which define their ion-conducting properties and gating by mechanical stimuli, respectively. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Piezo2: A Candidate Biomarker for Visceral Hypersensitivity in Irritable Bowel Syndrome?

    OpenAIRE

    Bai, Tao; Li, Ying; Xia, Jing; Jiang, Yudong; Zhang, Lei; Wang, Huan; Qian, Wei; Song, Jun; Hou, Xiaohua

    2017-01-01

    Background/Aims Currently, there exists no biomarker for visceral hypersensitivity in irritable bowel syndrome (IBS). Piezo proteins have been proven to play an important role in the mechanical stimulation to induce visceral pain in other tissues and may also be a biomarker candidate. The aim of this study was to test the expressions of Piezo1 and Piezo2 proteins in the intestinal epithelial cells from different intestinal segments and to explore the correlation between Piezo proteins express...

  2. Piezo-optical and electro-optical behaviour of nematic liquid crystals dispersed in a ferroelectric copolymer matrix

    International Nuclear Information System (INIS)

    Ganesan, Lakshmi Meena; Wirges, Werner; Gerhard, Reimund; Mellinger, Axel

    2010-01-01

    Polymer-dispersed liquid crystals (PDLCs) are composite materials that consist of micrometre-sized liquid-crystal (LC) droplets embedded in a polymer matrix. From ferroelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) and a nematic LC, PDLC films containing 10 and 60 wt% LC were prepared, and their electro-optical and piezo-optical behaviour was investigated. The electric field that is generated by the application of mechanical stress leads to changes in the transmittance of the PDLC film through a combination of piezoelectric and electro-optical effects. Such a piezo-optical PDLC material may be useful, e.g., in sensing and visualization applications.

  3. Theoretical study of piezo-phototronic nano-LEDs.

    Science.gov (United States)

    Liu, Ying; Niu, Simiao; Yang, Qing; Klein, Benjamin D B; Zhou, Yu Sheng; Wang, Zhong Lin

    2014-11-12

    Two-dimensional finite-element simulation of the piezo-phototronic effect in p-n-junction-based devices is carried out for the first time. A charge channel can be induced at the p-n junction interface when strain is applied, given the n-side is a piezoelectric semiconductor and the p-type side is non-piezoelectric semiconductor. This provides the first simulated evidence supporting the previously suggested mechanism responsible for the experimentally observed gigantic change of light-emission efficiency in piezo-phototronic light-emitting devices. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Performance Study of the Natural Rubber Composite with Clay Minerals

    International Nuclear Information System (INIS)

    Nyo Nyo Myint; Tin Tin Aye; Kyaw Myo Naing; Nyunt Wynn

    2008-03-01

    The preparation, characterization and some applications of natural rubber clay composite have been studied. This study investigated the possibility of natural rubber latex to replace some part of natural clays. In formulation of rubber clay composite from natural rubber latex and various clay minerals, three main steps were involved (i) preparation of latex cream (ii) prevulcanization of latex cream (iii) mixing vulcanized latex compound, with other ingredients. In each step, several parameters have been carefully investigated to optimize the performance of natural rubber clay composite production. The composite products were of better quality and can be considered to be more cost effective.

  5. High Performance Thin-Film Composite Forward Osmosis Membrane

    KAUST Repository

    Yip, Ngai Yin; Tiraferri, Alberto; Phillip, William A.; Schiffman, Jessica D.; Elimelech, Menachem

    2010-01-01

    obstacle hindering further advancements of this technology. This work presents the development of a high performance thin-film composite membrane for forward osmosis applications. The membrane consists of a selective polyamide active layer formed

  6. A Tour de Force: The Discovery, Properties, and Function of Piezo Channels.

    Science.gov (United States)

    Gottlieb, P A

    2017-01-01

    Mechanical transducers appear throughout cell biology and are used to convert mechanical stress into chemical or electrical signals that allow the cell to respond to environmental changes. In the past six years, a eukaryotic mechanical channel family with two members, Piezo1 and Piezo2, has been identified. Piezo1 was shown to be a cation-selective channel that does not require ancillary proteins for activity. Mouse Piezo1 is large, with over 2500 amino acids, and is not homologous to other ion channels. Both piezo channels have rapid voltage-dependent inactivation with a reversal potential near 0mV. The CryoEm structure of Piezo1 at 4.8Å shows trimer stoichiometry. Since the discovery of the piezo channels, their roles in the physiological response of cells have started to emerge. Significant progress has been made in understanding the intrinsic properties of the channels and how these properties are modulated by cytoskeletal elements. Specific diseases, such as hereditary xerocytosis affecting red blood cells, have mutations in Piezo1 that alter the cell's response to force, typically slowing inactivation and introducing a latency for activation. A number of physiological functions for piezo channels have been identified. These range from sensing the stiffness of surrounding substrate, to the response to light touch, to serotonin release from the gut. This review provides a general overview of the properties and roles of Piezo1 and Piezo2 in eukaryotic mechanotransduction. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. High performance dental resin composites with hydrolytically stable monomers.

    Science.gov (United States)

    Wang, Xiaohong; Huyang, George; Palagummi, Sri Vikram; Liu, Xiaohui; Skrtic, Drago; Beauchamp, Carlos; Bowen, Rafael; Sun, Jirun

    2018-02-01

    The objectives of this project were to: 1) develop strong and durable dental resin composites by employing new monomers that are hydrolytically stable, and 2) demonstrate that resin composites based on these monomers perform superiorly to the traditional bisphenol A glycidyl dimethacrylate/triethylene glycol dimethacrylate (Bis-GMA/TEGDMA) composites under testing conditions relevant to clinical applications. New resins comprising hydrolytically stable, ether-based monomer, i.e., triethylene glycol divinylbenzyl ether (TEG-DVBE), and urethane dimethacrylate (UDMA) were produced via composition-controlled photo-polymerization. Their composites contained 67.5wt% of micro and 7.5wt% of nano-sized filler. The performances of both copolymers and composites were evaluated by a battery of clinically-relevant assessments: degree of vinyl conversion (DC: FTIR and NIR spectroscopy); refractive index (n: optical microscopy); elastic modulus (E), flexural strength (F) and fracture toughness (K IC ) (universal mechanical testing); Knoop hardness (HK; indentation); water sorption (W sp ) and solubility (W su ) (gravimetry); polymerization shrinkage (S v ; mercury dilatometry) and polymerization stress (tensometer). The experimental UDMA/TEG-DVBE composites were compared with the Bis-GMA/TEGDMA composites containing the identical filler contents, and with the commercial micro hybrid flowable composite. UDMA/TEG-DBVE composites exhibited n, E, W sp , W su and S v equivalent to the controls. They outperformed the controls with respect to F (up to 26.8% increase), K IC (up to 27.7% increase), modulus recovery upon water sorption (full recovery vs. 91.9% recovery), and stress formation (up to 52.7% reduction). In addition, new composites showed up to 27.7% increase in attainable DC compared to the traditional composites. Bis-GMA/TEGDMA controls exceeded the experimental composites with respect to only one property, the composite hardness. Significantly, up to 18.1% lower HK values in

  8. Touch, Tension, and Transduction - The Function and Regulation of Piezo Ion Channels.

    Science.gov (United States)

    Wu, Jason; Lewis, Amanda H; Grandl, Jörg

    2017-01-01

    In 2010, two proteins, Piezo1 and Piezo2, were identified as the long-sought molecular carriers of an excitatory mechanically activated current found in many cells. This discovery has opened the floodgates for studying a vast number of mechanotransduction processes. Over the past 6 years, groundbreaking research has identified Piezos as ion channels that sense light touch, proprioception, and vascular blood flow, ruled out roles for Piezos in several other mechanotransduction processes, and revealed the basic structural and functional properties of the channel. Here, we review these findings and discuss the many aspects of Piezo function that remain mysterious, including how Piezos convert a variety of mechanical stimuli into channel activation and subsequent inactivation, and what molecules and mechanisms modulate Piezo function. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Touch, Tension, and Transduction – the Function and Regulation of Piezo Ion Channels

    Science.gov (United States)

    Wu, Jason; Lewis, Amanda; Grandl, Jörg

    2016-01-01

    In 2010, two proteins, Piezo1 and Piezo2, were identified as the long-sought molecular carriers of an excitatory mechanically activated current found in many cells. This discovery has opened the floodgates for studying a vast number of mechanotransduction processes. Over the past six years, groundbreaking research has identified Piezos as ion channels that sense light touch, proprioception, and vascular blood flow, ruled out roles for Piezos in several other mechanotransduction processes, and revealed the basic structural and functional properties of the channel. Here, we review these findings and discuss the many aspects of Piezo function that remain mysterious, including how Piezos convert a variety of mechanical stimuli into channel activation and subsequent inactivation, and what molecules and mechanisms modulate Piezo function. PMID:27743844

  10. Piezo-phototronic UV/visible photosensing with optical-fiber-nanowire hybridized structures.

    Science.gov (United States)

    Wang, Zhaona; Yu, Ruomeng; Pan, Caofeng; Liu, Ying; Ding, Yong; Wang, Zhong Lin

    2015-03-04

    An optical-fiber-nanowire hybridized UV-visible photodetector (PD) is reported. The PD is designed to allow direct integration in optical communication systems without requiring the use of couplers via fiber-welding technology. The PD works in two modes: axial and off-axial illumination mode. By using the piezo-phototronic effect, the performance of the PD is enhanced/optimized by up to 718% in sensitivity and 2067% in photoresponsivity. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. The dynamics of the piezo inkjet printhead operation

    NARCIS (Netherlands)

    Wijshoff, H.M.A.

    2010-01-01

    The operation of a piezo inkjet printhead involves a chain of processes in many physical domains at different length scales. The final goal is the formation of droplets of all kinds of fluids with any desired volume, velocity, and a reliability as high as possible. The physics behind the chain of

  12. Air Entrapment and Drop Formation in Piezo Inkjet Printing

    NARCIS (Netherlands)

    van der Bos, J.A.

    2011-01-01

    Piezo drop-on-demand (DOD) inkjet printers are used in an increasing number of applications for their reliable deposition of droplets onto a substrate. Droplets of a few picoliters are ejected from an ink jet nozzle at a frequency of up to 50 kHz. However, entrapment of an air microbubble into the

  13. Air entrapment in piezo-driven inkjet printheads

    NARCIS (Netherlands)

    de Jong, J.; de Bruin, G.J.; de Bruin, Gerrit; Reinten, Hans; van den Berg, Marc; Wijshoff, Herman; Wijshoff, H.; Versluis, Michel; Lohse, Detlef

    2006-01-01

    The stability of inkjet printers is a major requirement for high-quality-printing. However, in piezo-driven inkjet printheads, air entrapment can lead to malfunctioning of the jet formation. The piezoactuator is employed to actively monitor the channel acoustics and to identify distortions at an

  14. Piezo-Phototronic Matrix via a Nanowire Array.

    Science.gov (United States)

    Zhang, Yang; Zhai, Junyi; Wang, Zhong Lin

    2017-12-01

    Piezoelectric semiconductors, such as ZnO and GaN, demonstrate multiproperty coupling effects toward various aspects of mechanical, electrical, and optical excitation. In particular, the three-way coupling among semiconducting, photoexcitation, and piezoelectric characteristics in wurtzite-structured semiconductors is established as a new field, which was first coined as piezo-phototronics by Wang in 2010. The piezo-phototronic effect can controllably modulate the charge-carrier generation, separation, transport, and/or recombination in optical-electronic processes by modifying the band structure at the metal-semiconductor or semiconductor-semiconductor heterojunction/interface. Here, the progress made in using the piezo-phototronic effect for enhancing photodetectors, pressure sensors, light-emitting diodes, and solar cells is reviewed. In comparison with previous works on a single piezoelectric semiconducting nanowire, piezo-phototronic nanodevices built using nanowire arrays provide a promising platform for fabricating integrated optoelectronics with the realization of high-spatial-resolution imaging and fast responsivity. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Extremely stable piezo mechanisms for the New Gravitational Wave Observatory

    NARCIS (Netherlands)

    Pijnenburg, J.A.C.M.; Rijnveld, N.; Hogenhuis, H.

    2012-01-01

    Detection and observation of gravitational waves requires extreme stability in the frequency range 3e-5 Hz to 1 Hz. NGO/LISA will attain this by creating a giant interferometer in space, based on free floating proof masses in three spacecrafts. To operate NGO/LISA, the following piezo mechanisms are

  16. H∞ control of piezo actuated tilting mirror mechanism

    NARCIS (Netherlands)

    Van Dijk, J.

    2015-01-01

    In here the high bandwidth (2000 Hz.) feedback control of a precision mechanisms driven by a piezo actuator demanding a high absolute accuracy is discussed. The mechanism considered is rotating a mirror for laser bundle manipulation. It will be shown that a loopshaping controller design using the

  17. Piezo-Electrochemical Energy Harvesting with Lithium-Intercalating Carbon Fibers.

    Science.gov (United States)

    Jacques, Eric; Lindbergh, Göran; Zenkert, Dan; Leijonmarck, Simon; Kjell, Maria Hellqvist

    2015-07-01

    The mechanical and electrochemical properties are coupled through a piezo-electrochemical effect in Li-intercalated carbon fibers. It is demonstrated that this piezo-electrochemical effect makes it possible to harvest electrical energy from mechanical work. Continuous polyacrylonitrile-based carbon fibers that can work both as electrodes for Li-ion batteries and structural reinforcement for composites materials are used in this study. Applying a tensile force to carbon fiber bundles used as Li-intercalating electrodes results in a response of the electrode potential of a few millivolts which allows, at low current densities, lithiation at higher electrode potential than delithiation. More electrical energy is thereby released from the cell at discharge than provided at charge, harvesting energy from the mechanical work of the applied force. The measured harvested specific electrical power is in the order of 1 μW/g for current densities in the order of 1 mA/g, but this has a potential of being increased significantly.

  18. The Kinetics and the Permeation Properties of Piezo Channels.

    Science.gov (United States)

    Gnanasambandam, R; Gottlieb, P A; Sachs, F

    2017-01-01

    Piezo channels are eukaryotic, cation-selective mechanosensitive channels (MSCs), which show rapid activation and voltage-dependent inactivation. The kinetics of these channels are largely consistent across multiple cell types and different stimulation paradigms with some minor variability. No accessory subunits that associate with Piezo channels have been reported. They are homotrimers and each ∼300kD monomer has an N-terminal propeller blade-like mechanosensing module, which can confer mechanosensing capabilities on ASIC-1 (the trimeric non-MSC, acid-sensing ion channel-1) and a C-terminal pore module, which influences conductance, selectivity, and channel inactivation. Repeated stimulation can cause domain fracture and diffusion of these channels leading to synchronous loss of inactivation. The reconstituted channels spontaneously open only in asymmetric bilayers but lack inactivation. Mutations that cause hereditary xerocytosis alter PIEZO1 kinetics. The kinetics of the wild-type PIEZO1 and alterations thereof in mutants (M2225R, R2456K, and DhPIEZO1) are summarized in the form of a quantitative model and hosted online. The pore is permeable to alkali ions although Li + permeates poorly. Divalent cations, notably Ca 2+ , traverse the channel and inhibit the flux of monovalents. The large monovalent organic cations such as tetramethyl ammonium and tetraethyl ammonium can traverse the channel, but slowly, suggesting a pore diameter of ∼8Å, and the estimated in-plane area change upon opening is around 6-20nm 2 . Ruthenium red can enter the channel only from the extracellular side and seems to bind in a pocket close to residue 2496. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Ionic Selectivity and Permeation Properties of Human PIEZO1 Channels.

    Directory of Open Access Journals (Sweden)

    Radhakrishnan Gnanasambandam

    Full Text Available Members of the eukaryotic PIEZO family (the human orthologs are noted hPIEZO1 and hPIEZO2 form cation-selective mechanically-gated channels. We characterized the selectivity of human PIEZO1 (hPIEZO1 for alkali ions: K+, Na+, Cs+ and Li+; organic cations: TMA and TEA, and divalents: Ba2+, Ca2+, Mg2+ and Mn2+. All monovalent ions permeated the channel. At a membrane potential of -100 mV, Cs+, Na+ and K+ had chord conductances in the range of 35-55 pS with the exception of Li+, which had a significantly lower conductance of ~ 23 pS. The divalents decreased the single-channel permeability of K+, presumably because the divalents permeated slowly and occupied the open channel for a significant fraction of the time. In cell-attached mode, 90 mM extracellular divalents had a conductance for inward currents carried by the divalents of: 25 pS for Ba2+ and 15 pS for Ca2+ at -80 mV and 10 pS for Mg2+ at -50 mV. The organic cations, TMA and TEA, permeated slowly and attenuated K+ currents much like the divalents. As expected, the channel K+ conductance increased with K+ concentration saturating at ~ 45 pS and the KD of K+ for the channel was 32 mM. Pure divalent ion currents were of lower amplitude than those with alkali ions and the channel opening rate was lower in the presence of divalents than in the presence of monovalents. Exposing cells to the actin disrupting reagent cytochalasin D increased the frequency of openings in cell-attached patches probably by reducing mechanoprotection.

  20. PHYSICAL PERFORMANCE AND BODY COMPOSITION IN MAINTENANCE HEMODIALYSIS (MHD PATIENTS

    Directory of Open Access Journals (Sweden)

    M Zhang

    2012-06-01

    Conclusions: These findings indicate that adult MHD pts had a higher % body fat. Measures of physical performance were markedly reduced in MHD pts as compared to Normals. Physical performance in MHD, measured especially by 6-MW, correlated negatively with some measures of body composition, particularly with LBMI.

  1. Bodies in Composition: Teaching Writing through Kinesthetic Performance

    Science.gov (United States)

    Butler, Janine

    2017-01-01

    This article calls on composition instructors to reflect consciously on how we can use our bodies kinesthetically to perform multimodal writing processes through gestural, visual, and spatial modes. Teaching writing through kinesthetic performance can show students that our bodies are being constructed via interaction with audiences, akin to the…

  2. Autoclave cycle optimization for high performance composite parts manufacturing

    OpenAIRE

    Nele, L.; Caggiano, A.; Teti, R.

    2016-01-01

    In aeronautical production, autoclave curing of composite parts must be performed according to a specified diagram of temperature and pressure vs time. Part-tool assembly thermal inertia and shape have a large influence on the heating and cooling rate, and therefore on the dwell time within the target temperature range. When simultaneously curing diverse composite parts, the total autoclave cycle time is driven by the part-tool assembly with the lower heating and cooling rates. With the aim t...

  3. High-bandwidth and flexible tracking control for precision motion with application to a piezo nanopositioner.

    Science.gov (United States)

    Feng, Zhao; Ling, Jie; Ming, Min; Xiao, Xiao-Hui

    2017-08-01

    For precision motion, high-bandwidth and flexible tracking are the two important issues for significant performance improvement. Iterative learning control (ILC) is an effective feedforward control method only for systems that operate strictly repetitively. Although projection ILC can track varying references, the performance is still limited by the fixed-bandwidth Q-filter, especially for triangular waves tracking commonly used in a piezo nanopositioner. In this paper, a wavelet transform-based linear time-varying (LTV) Q-filter design for projection ILC is proposed to compensate high-frequency errors and improve the ability to tracking varying references simultaneously. The LVT Q-filter is designed based on the modulus maximum of wavelet detail coefficients calculated by wavelet transform to determine the high-frequency locations of each iteration with the advantages of avoiding cross-terms and segmenting manually. The proposed approach was verified on a piezo nanopositioner. Experimental results indicate that the proposed approach can locate the high-frequency regions accurately and achieve the best performance under varying references compared with traditional frequency-domain and projection ILC with a fixed-bandwidth Q-filter, which validates that through implementing the LTV filter on projection ILC, high-bandwidth and flexible tracking can be achieved simultaneously by the proposed approach.

  4. Improved electrochemical performance of hierarchical porous carbon/polyaniline composites

    International Nuclear Information System (INIS)

    Hu Juan; Wang Huanlei; Huang Xiao

    2012-01-01

    Highlights: ► Polyaniline-coated hierarchical porous carbon (HPC) composites have been synthesized by in situ polymerization. ► The HPC/polyaniline composite has significantly better electrochemical capacitance performance than pure HPC and polyaniline. ► The amount of polyaniline loading has a significant effect on the composites’ electrochemical performances. - Abstract: Polyaniline (PANI)-coated hierarchical porous carbon (HPC) composites (HPC/PANI) for use as supercapacitor electrodes were prepared by in situ chemical oxidation polymerization at 273 K of an aniline solution containing well-dispersed HPC particles. After polymerization, a thin layer of PANI was coated on the surface of the HPC particles, which was confirmed by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope (TEM) and scanning electron microscopy (SEM). Compared to pure PANI and HPC, the electrochemical capacitance performance of the composites was significantly improved. The highest specific capacitance of the composites obtained is 478 F g −1 at 1 mV s −1 , which is more than twice as that of pure PANI and three times as that of pure HPC. Because of the influence from the hierarchical pore structure of the carbon material, the calculated specific capacitance of PANI in the composite (pseudocapacitance contribution from PANI) is almost one magnitude higher than that of pure PANI.

  5. Axisymmetric Vibration of Piezo-Lemv Composite Hollow Multilayer Cylinder

    Directory of Open Access Journals (Sweden)

    E. S. Nehru

    2012-01-01

    Full Text Available Axisymmetric vibration of an infinite piezolaminated multilayer hollow cylinder made of piezoelectric layers of 6 mm class and an isotropic LEMV (Linear Elastic Materials with Voids layers is studied. The frequency equations are obtained for the traction free outer surface with continuity conditions at the interfaces. Numerical results are carried out for the inner, middle, and outer hollow piezoelectric layers bonded by LEMV (It is hypothetical material layers and the dispersion curves are compared with that of a similar 3-layer model and of 3 and 5 layer models with inner, middle, and outer hollow piezoelectric layers bonded by CFRP (Carbon fiber reinforced plastics.

  6. Effect of MnO2, Bi2O3, and ZnO additions on the electrical properties of lead zirconate titanate piezo ceramics

    International Nuclear Information System (INIS)

    Klimov, V.V.; Selikova, N.I.; Bronnikov, A.N.

    2006-01-01

    The effect of manganese dioxide additions on the electrical properties of lead zirconate titanate (PZT) piezo ceramics has been investigated. The results demonstrate that, taken alone, manganese dioxide does not ensure the formation of hard PZT. The valence state of manganese in the piezo ceramics is shown to be 4+ if no other dopants are present and 3+ if manganese is introduced in combination with Bi and Zn. Microstructural examination indicates that the grain size of the singly doped ceramics is 5-15 μm, while that of the codoped ceramics is 1-3 μm. The polarization current curves of the piezo ceramics containing manganese, bismuth, and zinc oxides have extra maxima, which points to significant internal fields. The manganese is shown to reside at grain boundaries. The conclusion is made that it is the composition of Mn-containing intergranular phases, rather than the presence of manganese ions, that plays a key role in the formation of hard piezo ceramics [ru

  7. Synthesis of CdS nanorod arrays and their applications in flexible piezo-driven active H2S sensors

    International Nuclear Information System (INIS)

    Wang, Penglei; Deng, Ping; Nie, Yuxin; Zhao, Yayu; Xing, Lili; Xue, Xinyu; Zhang, Yan

    2014-01-01

    A flexible piezo-driven active H 2 S sensor has been fabricated from CdS nanorod arrays. By coupling the piezoelectric and gas sensing properties of CdS nanorods, the piezoelectric output generated by CdS nanorod arrays acts not only as a power source, but also as a response signal to H 2 S. Under externally applied compressive force, the piezoelectric output of CdS nanorod arrays is very sensitive to H 2 S. Upon exposure to 600 ppm H 2 S, the piezoelectric output of the device decreased from 0.32 V (in air) to 0.12 V. Such a flexible device can be driven by the tiny mechanical energy in our living environment, such as human finger pinching. Our research can stimulate a research trend on designing new material systems and device structures for high-performance piezo-driven active gas sensors. (paper)

  8. Master-slave control with trajectory planning and Bouc-Wen model for tracking control of piezo-driven stage

    Science.gov (United States)

    Lu, Xiaojun; Liu, Changli; Chen, Lei

    2018-04-01

    In this paper, a redundant Piezo-driven stage having 3RRR compliant mechanism is introduced, we propose the master-slave control with trajectory planning (MSCTP) strategy and Bouc-Wen model to improve its micro-motion tracking performance. The advantage of the proposed controller lies in that its implementation only requires a simple control strategy without the complexity of modeling to avoid the master PEA's tracking error. The dynamic model of slave PEA system with Bouc-Wen hysteresis is established and identified via particle swarm optimization (PSO) approach. The Piezo-driven stage with operating period T=1s and 2s is implemented to track a prescribed circle. The simulation results show that MSCTP with Bouc-Wen model reduces the trajectory tracking errors to the range of the accuracy of our available measurement.

  9. Oxygen Reduction Reaction for Generating H2 O2 through a Piezo-Catalytic Process over Bismuth Oxychloride.

    Science.gov (United States)

    Shao, Dengkui; Zhang, Ling; Sun, Songmei; Wang, Wenzhong

    2018-02-09

    Oxygen reduction reaction (ORR) for generating H 2 O 2 through green pathways have gained much attention in recent years. Herein, we introduce a piezo-catalytic approach to obtain H 2 O 2 over bismuth oxychloride (BiOCl) through an ORR pathway. The piezoelectric response of BiOCl was directly characterized by piezoresponse force microscopy (PFM). The BiOCl exhibits efficient catalytic performance for generating H 2 O 2 (28 μmol h -1 ) only from O 2 and H 2 O, which is above the average level of H 2 O 2 produced by solar-to-chemical processes. A piezo-catalytic mechanism was proposed: with ultrasonic waves, an alternating electric field will be generated over BiOCl, which can drive charge carriers (electrons) to interact with O 2 and H 2 O, then to form H 2 O 2 . © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. High Performance Fiber Reinforced Cement Composites 6 HPFRCC 6

    CERN Document Server

    Reinhardt, Hans; Naaman, A

    2012-01-01

    High Performance Fiber Reinforced Cement Composites (HPFRCC) represent a class of cement composites whose stress-strain response in tension undergoes strain hardening behaviour accompanied by multiple cracking, leading to a high strain prior to failure. The primary objective of this International Workshop was to provide a compendium of up-to-date information on the most recent developments and research advances in the field of High Performance Fiber Reinforced Cement Composites. Approximately 65 contributions from leading world experts are assembled in these proceedings and provide an authoritative perspective on the subject. Special topics include fresh and hardening state properties; self-compacting mixtures; mechanical behavior under compressive, tensile, and shear loading; structural applications; impact, earthquake and fire resistance; durability issues; ultra-high performance fiber reinforced concrete; and textile reinforced concrete. Target readers: graduate students, researchers, fiber producers, desi...

  11. Wound healing of osteotomy defects prepared with piezo or conventional surgical instruments: a pilot study in rabbits.

    Science.gov (United States)

    Ma, Li; Mattheos, Nikos; Sun, Yan; Liu, Xi Ling; Yip Chui, Ying; Lang, Niklaus Peter

    2015-08-01

    The aim of the present study was to evaluate and compare the wound-healing process following osteotomies performed with either conventional rotary burs or piezoelectric surgery in a rabbit model. Two types of osteotomy window defects of the nasal cavities were prepared on the nasal bone of 16 adult New Zealand white rabbits with either a conventional rotary bur or piezo surgery. The defects were covered with a resorbable membrane. Four animals were killed at 1, 2, 3, and 5 weeks after the surgical procedure, respectively. Histological and morphometric evaluations were performed to assess the volumetric density of various tissue components: the blood clot, vascularized structures, provisional matrix, osteoid, mineralized bone, bone debris, residual tissue, and old bone. Significantly more bone debris was found at 1 week in the conventionally-prepared defects compared to the piezo surgically-prepared defects. At 2 and 3 weeks, a newly-formed hard tissue bridge, mainly composed of woven bone, was seen; however, no statistically-significant differences were observed. At 5 weeks, the defects were completely filled with newly-formed bone. The defects prepared by piezo surgery showed a significantly decreased proportion of bone debris at 1 week, compared to conventional rotary bur defect. © 2014 Wiley Publishing Asia Pty Ltd.

  12. Numerical Modelling of a Piezo Roof Harvesting System: The Right Component Selection

    Directory of Open Access Journals (Sweden)

    Di Leo Romeo

    2017-06-01

    Full Text Available The present work focuses on a first study for a piezoelectric harvesting system, finalized to the obtaining of electrical energy from the kinetic energy of rainy precipitation, a renewable energy source not really considered until now. The system, after the realization, can be collocated on the roof of an house, configuring a “Piezo Roof Harvesting System”. After presenting a state of art of the harvesting systems from environmental energy, linked to vibrations, using piezoelectric structures, and of piezoelectric harvesting systems functioning with rain, the authors propose an analysis of the fundamental features of rainy precipitations for the definition of the harvesting system. Then, four key patterns for the realization of a piezoelectric energy harvesting system are discussed and analysed, arriving to the choice of a cantilever beam scheme, in which the piezoelectric material works in 31 mode. An electro-mechanical model for the simulation of performance of the unit for the energetic conversion, composed of three blocks, is proposed. The model is used for a simulation campaign to perform the final choice of the more suitable piezoelectric unit, available on the market, which will be adopted for the realization of the “Piezo Roof Harvesting System”.

  13. Enhancing the Efficiency of Silicon-Based Solar Cells by the Piezo-Phototronic Effect.

    Science.gov (United States)

    Zhu, Laipan; Wang, Longfei; Pan, Caofeng; Chen, Libo; Xue, Fei; Chen, Baodong; Yang, Leijing; Su, Li; Wang, Zhong Lin

    2017-02-28

    Although there are numerous approaches for fabricating solar cells, the silicon-based photovoltaics are still the most widely used in industry and around the world. A small increase in the efficiency of silicon-based solar cells has a huge economic impact and practical importance. We fabricate a silicon-based nanoheterostructure (p + -Si/p-Si/n + -Si (and n-Si)/n-ZnO nanowire (NW) array) photovoltaic device and demonstrate the enhanced device performance through significantly enhanced light absorption by NW array and effective charge carrier separation by the piezo-phototronic effect. The strain-induced piezoelectric polarization charges created at n-doped Si-ZnO interfaces can effectively modulate the corresponding band structure and electron gas trapped in the n + -Si/n-ZnO NW nanoheterostructure and thus enhance the transport process of local charge carriers. The efficiency of the solar cell was improved from 8.97% to 9.51% by simply applying a static compress strain. This study indicates that the piezo-phototronic effect can enhance the performance of a large-scale silicon-based solar cell, with great potential for industrial applications.

  14. Largely Improved Near-Infrared Silicon-Photosensing by the Piezo-Phototronic Effect.

    Science.gov (United States)

    Dai, Yejing; Wang, Xingfu; Peng, Wenbo; Zou, Haiyang; Yu, Ruomeng; Ding, Yong; Wu, Changsheng; Wang, Zhong Lin

    2017-07-25

    Although silicon (Si) devices are the backbone of modern (opto-)electronics, infrared Si-photosensing suffers from low-efficiency due to its limitation in light-absorption. Here, we demonstrate a large improvement in the performance, equivalent to a 366-fold enhancement in photoresponsivity, of a Si-based near-infrared (NIR) photodetector (PD) by introducing the piezo-phototronic effect via a deposited CdS layer. By externally applying a -0.15‰ compressive strain to the heterojunction, carrier-dynamics modulation at the local junction can be induced by the piezoelectric polarization, and the photoresponsivity and detectivity of the PD exhibit an enhancement of two orders of magnitude, with the peak values up to 19.4 A/W and 1.8 × 10 12 cm Hz 1/2 /W, respectively. The obtained maximum responsivity is considerably larger than those of commercial Si and InGaAs PDs in the NIR waveband. Meanwhile, the rise time and fall time are reduced by 84.6% and 76.1% under the external compressive strain. This work provides a cost-effective approach to achieve high-performance NIR photosensing by the piezo-phototronic effect for high-integration Si-based optoelectronic systems.

  15. The role of Drosophila Piezo in mechanical nociception.

    Science.gov (United States)

    Kim, Sung Eun; Coste, Bertrand; Chadha, Abhishek; Cook, Boaz; Patapoutian, Ardem

    2012-02-19

    Transduction of mechanical stimuli by receptor cells is essential for senses such as hearing, touch and pain. Ion channels have a role in neuronal mechanotransduction in invertebrates; however, functional conservation of these ion channels in mammalian mechanotransduction is not observed. For example, no mechanoreceptor potential C (NOMPC), a member of transient receptor potential (TRP) ion channel family, acts as a mechanotransducer in Drosophila melanogaster and Caenorhabditis elegans; however, it has no orthologues in mammals. Degenerin/epithelial sodium channel (DEG/ENaC) family members are mechanotransducers in C. elegans and potentially in D. melanogaster; however, a direct role of its mammalian homologues in sensing mechanical force has not been shown. Recently, Piezo1 (also known as Fam38a) and Piezo2 (also known as Fam38b) were identified as components of mechanically activated channels in mammals. The Piezo family are evolutionarily conserved transmembrane proteins. It is unknown whether they function in mechanical sensing in vivo and, if they do, which mechanosensory modalities they mediate. Here we study the physiological role of the single Piezo member in D. melanogaster (Dmpiezo; also known as CG8486). Dmpiezo expression in human cells induces mechanically activated currents, similar to its mammalian counterparts. Behavioural responses to noxious mechanical stimuli were severely reduced in Dmpiezo knockout larvae, whereas responses to another noxious stimulus or touch were not affected. Knocking down Dmpiezo in sensory neurons that mediate nociception and express the DEG/ENaC ion channel pickpocket (ppk) was sufficient to impair responses to noxious mechanical stimuli. Furthermore, expression of Dmpiezo in these same neurons rescued the phenotype of the constitutive Dmpiezo knockout larvae. Accordingly, electrophysiological recordings from ppk-positive neurons revealed a Dmpiezo-dependent, mechanically activated current. Finally, we found that Dmpiezo

  16. Composite Materials for Thermal Energy Storage: Enhancing Performance through Microstructures

    Science.gov (United States)

    Ge, Zhiwei; Ye, Feng; Ding, Yulong

    2014-01-01

    Chemical incompatibility and low thermal conductivity issues of molten-salt-based thermal energy storage materials can be addressed by using microstructured composites. Using a eutectic mixture of lithium and sodium carbonates as molten salt, magnesium oxide as supporting material, and graphite as thermal conductivity enhancer, the microstructural development, chemical compatibility, thermal stability, thermal conductivity, and thermal energy storage performance of composite materials are investigated. The ceramic supporting material is essential for preventing salt leakage and hence provides a solution to the chemical incompatibility issue. The use of graphite gives a significant enhancement on the thermal conductivity of the composite. Analyses suggest that the experimentally observed microstructural development of the composite is associated with the wettability of the salt on the ceramic substrate and that on the thermal conduction enhancer. PMID:24591286

  17. Composite materials for thermal energy storage: enhancing performance through microstructures.

    Science.gov (United States)

    Ge, Zhiwei; Ye, Feng; Ding, Yulong

    2014-05-01

    Chemical incompatibility and low thermal conductivity issues of molten-salt-based thermal energy storage materials can be addressed by using microstructured composites. Using a eutectic mixture of lithium and sodium carbonates as molten salt, magnesium oxide as supporting material, and graphite as thermal conductivity enhancer, the microstructural development, chemical compatibility, thermal stability, thermal conductivity, and thermal energy storage performance of composite materials are investigated. The ceramic supporting material is essential for preventing salt leakage and hence provides a solution to the chemical incompatibility issue. The use of graphite gives a significant enhancement on the thermal conductivity of the composite. Analyses suggest that the experimentally observed microstructural development of the composite is associated with the wettability of the salt on the ceramic substrate and that on the thermal conduction enhancer. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Tribological performance of polymer composites used in electrical ...

    Indian Academy of Sciences (India)

    engineering applications. ZAFER DEMIR. Anadolu University, Eskisehir, Turkey. MS received 28 December 2011; revised 13 March 2012. Abstract. Sliding wear performance of 20% mica-filled polyamide 6 (PA6 + 20% mica) and 20% short glass fibre- reinforced polysulphone (PSU + 20 GFR) polymer composites used in ...

  19. High performance thin-film composite forward osmosis membrane.

    Science.gov (United States)

    Yip, Ngai Yin; Tiraferri, Alberto; Phillip, William A; Schiffman, Jessica D; Elimelech, Menachem

    2010-05-15

    Recent studies show that osmotically driven membrane processes may be a viable technology for desalination, water and wastewater treatment, and power generation. However, the absence of a membrane designed for such processes is a significant obstacle hindering further advancements of this technology. This work presents the development of a high performance thin-film composite membrane for forward osmosis applications. The membrane consists of a selective polyamide active layer formed by interfacial polymerization on top of a polysulfone support layer fabricated by phase separation onto a thin (40 mum) polyester nonwoven fabric. By careful selection of the polysulfone casting solution (i.e., polymer concentration and solvent composition) and tailoring the casting process, we produced a support layer with a mix of finger-like and sponge-like morphologies that give significantly enhanced membrane performance. The structure and performance of the new thin-film composite forward osmosis membrane are compared with those of commercial membranes. Using a 1.5 M NaCl draw solution and a pure water feed, the fabricated membranes produced water fluxes exceeding 18 L m(2-)h(-1), while consistently maintaining observed salt rejection greater than 97%. The high water flux of the fabricated thin-film composite forward osmosis membranes was directly related to the thickness, porosity, tortuosity, and pore structure of the polysulfone support layer. Furthermore, membrane performance did not degrade after prolonged exposure to an ammonium bicarbonate draw solution.

  20. High performance co-polyimide nanofiber reinforced composites

    NARCIS (Netherlands)

    Yao, Jian; Li, Guang; Bastiaansen, Cees; Peijs, Ton

    2015-01-01

    Electrospun co-polyimide BPDA (3, 3′, 4, 4′-Biphenyltetracarboxylic dianhydride)/PDA (p-Phenylenediamine)/ODA (4, 4′-oxydianiline) nanofiber reinforced flexible composites were manufactured by impregnating these high performance nanofibers with styrene-butadiene-styrene (SBS) triblock copolymer

  1. Composition of Exports and Export Performance of Eurozone Countries

    NARCIS (Netherlands)

    Wierts, P.J.; Kerkhoff, H.; de Haan, J.

    2014-01-01

    This article investigates to what extent the composition of exports is related to the export performance of eurozone countries using a data set on exports from the oldest eurozone countries to their top 20 trade partners for the period 1988-2009. The results suggest that a higher share of high

  2. High Performance Thin-Film Composite Forward Osmosis Membrane

    KAUST Repository

    Yip, Ngai Yin

    2010-05-15

    Recent studies show that osmotically driven membrane processes may be a viable technology for desalination, water and wastewater treatment, and power generation. However, the absence of a membrane designed for such processes is a significant obstacle hindering further advancements of this technology. This work presents the development of a high performance thin-film composite membrane for forward osmosis applications. The membrane consists of a selective polyamide active layer formed by interfacial polymerization on top of a polysulfone support layer fabricated by phase separation onto a thin (40 μm) polyester nonwoven fabric. By careful selection of the polysulfone casting solution (i.e., polymer concentration and solvent composition) and tailoring the casting process, we produced a support layer with a mix of finger-like and sponge-like morphologies that give significantly enhanced membrane performance. The structure and performance of the new thin-film composite forward osmosis membrane are compared with those of commercial membranes. Using a 1.5 M NaCl draw solution and a pure water feed, the fabricated membranes produced water fluxes exceeding 18 L m2-h-1, while consistently maintaining observed salt rejection greater than 97%. The high water flux of the fabricated thin-film composite forward osmosis membranes was directly related to the thickness, porosity, tortuosity, and pore structure of the polysulfone support layer. Furthermore, membrane performance did not degrade after prolonged exposure to an ammonium bicarbonate draw solution. © 2010 American Chemical Society.

  3. Evaluation of Shielding Performance for Newly Developed Composite Materials

    Science.gov (United States)

    Evans, Beren Richard

    This work details an investigation into the contributing factors behind the success of newly developed composite neutron shield materials. Monte Carlo simulation methods were utilized to assess the neutron shielding capabilities and secondary radiation production characteristics of aluminum boron carbide, tungsten boron carbide, bismuth borosilicate glass, and Metathene within various neutron energy spectra. Shielding performance and secondary radiation data suggested that tungsten boron carbide was the most effective composite material. An analysis of the macroscopic cross-section contributions from constituent materials and interaction mechanisms was then performed in an attempt to determine the reasons for tungsten boron carbide's success over the other investigated materials. This analysis determined that there was a positive correlation between a non-elastic interaction contribution towards a material's total cross-section and shielding performance within the thermal and epi-thermal energy regimes. This finding was assumed to be a result of the boron-10 absorption reaction. The analysis also determined that within the faster energy regions, materials featuring higher non-elastic interaction contributions were comparable to those exhibiting primarily elastic scattering via low Z elements. This allowed for the conclusion that composite shield success within higher energy neutron spectra does not necessitate the use elastic scattering via low Z elements. These findings suggest that the inclusion of materials featuring high thermal absorption properties is more critical to composite neutron shield performance than the presence of constituent materials more inclined to maximize elastic scattering energy loss.

  4. A Comparison of Electrolytic Capacitors and Supercapacitors for Piezo-Based Energy Harvesting

    Science.gov (United States)

    2013-07-01

    A Comparison of Electrolytic Capacitors and Supercapacitors for Piezo-Based Energy Harvesting by Matthew H. Ervin, Carlos M. Pereira, John R...Capacitors and Supercapacitors for Piezo-Based Energy Harvesting Matthew H. Ervin Sensors and Electronic Devices Directorate, ARL Carlos M. Pereira... Supercapacitors for Piezo-Based Energy Harvesting 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Matthew H

  5. The Function of the Novel Mechanical Activated Ion Channel Piezo1 in the Human Osteosarcoma Cells

    OpenAIRE

    Jiang, Long; Zhao, Yi-ding; Chen, Wei-xiang

    2017-01-01

    Background The Piezo1 protein ion channel is a novel mechanical activated ion channel which is related to mechanical signal transduction. However, the function of the mechanically activated ion channel Piezo1 had not been explored. In this study, we explored the function of the Piezo1 ion channel in human osteosarcoma (OS) cells related to apoptosis, invasion, and the cell proliferation. Material/Methods Reverse transcription polymerase chain reaction (RT-PCR) and western-blotting were used t...

  6. Theoretical and experimental evaluation of piezo-optic parameters and photoelastic constant in tetragonal PWO.

    Science.gov (United States)

    Natali, Pier Paolo; Montalto, Luigi; Daví, Fabrizio; Mengucci, Paolo; Ciriaco, Andrea; Paone, Nicola; Rinaldi, Daniele

    2018-02-01

    The tetragonal PbWO 4 (PWO) is one of the most important scintillating crystals, being used both in the Compact Muon Solenoid (CMS) experiment at the European Organization for Nuclear Research (CERN) and in the PANDA project at the Facility for Antiproton and Ion Research (FAIR). Light yield and other relevant scintillation properties depend, among many factors, also on the crystal mechanical quality. Accordingly, a detailed knowledge of crystal piezo-optic properties is a mandatory step toward understanding elasto-optic behavior and performing crystal quality control. In this paper, we evaluate for the first time, to the best of our knowledge, by means of both photoelastic and x-ray measurements, some components of the piezo-optic tensor; moreover, when the crystal is acted upon by a uniaxial stress, we obtain an evaluation for the rotation angle of the optic plane under stress as well as the photoelastic constant. These parameters are necessary to detect the residual stresses within the crystal, if any, and to give an overall quality measure. Such a methodology is in general suitable for any tetragonal crystals.

  7. High-Precision Control of a Piezo-Driven Nanopositioner Using Fuzzy Logic Controllers

    Directory of Open Access Journals (Sweden)

    Mohammed Altaher

    2018-01-01

    Full Text Available This paper presents single- and dual-loop fuzzy control schemes to precisely control the piezo-driven nanopositioner in the x- and y-axis directions. Various issues are associated with this control problem, such as low stability margin due to the sharp resonant peak, nonlinear dynamics, parameter uncertainty, etc. As such, damping controllers are often utilised to damp the mechanical resonance of the nanopositioners. The Integral Resonant Controller (IRC is used in this paper as a damping controller to damp the mechanical resonance. A further inherent problem is the hysteresis phenomenon (disturbance, which leads to degrading the positioning performance (accuracy of the piezo-driven stage. The common approach to treat this disturbance is to invoke tracking controllers in a closed-loop feedback scheme in conjunction with the damping controllers. The traditional approach uses the Integral Controller (I or Proportional Integral (PI as a tracking controller, whereas this paper introduces the Proportional and Integral (PI-like Fuzzy Logic Controller (FLC as a tracking controller. The effectiveness of the proposed control schemes over conventional schemes is confirmed through comparative simulation studies, and results are presented. The stability boundaries of the proposed control schemes are determined in the same way as with a conventional controller. Robustness against variations in the resonant frequency of the proposed control schemes is verified.

  8. Performance Evaluation of Refractory Composite Coatings in Potassium Rich Environment

    Directory of Open Access Journals (Sweden)

    Kristina BRINKIENĖ

    2016-09-01

    Full Text Available A laboratory scale method was used to study the performance of reinforced cement composites in potassium rich environment of biomass combustion. Buckwheat husk (BH was used as potential source of unexploited biomass product applicable as biomass derived fuel. In order to enhance the alkali effect on the properties of the investigated materials, the solution of potassium carbonate (K2CO3 was selected as potassium rich aggressive environment. Two reinforced cement composites as potential repair coatings for restoration of damaged refractory surfaces with different composition of aggregate were used in corrosion tests. Performance of refractory coatings was evaluated by analysing the microstructure of the treated composites as well as mechanical properties. Energy-dispersive X-ray spectroscopy (SEM/EDS and optical microscopy were used to study the microstructure in the corroded region of the refractory coatings. Long term studies in the solution of 1M K2CO3 for 56 months have demonstrated that composite with the additive of fluid cracking catalyst of oil refinery and petrochemical industries is more durable in the potassium rich environment.DOI: http://dx.doi.org/10.5755/j01.ms.22.3.8348

  9. Wear performance of garnet aluminium composites at high contact pressure

    Science.gov (United States)

    Sharma, Anju; Arora, Rama; Kumar, Suresh; Singh, Gurmel; Pandey, O. P.

    2016-05-01

    To satisfy the needs of the engineering sector, researchers and material scientists in this area adopted the development of composites with tailor made properties to enhance efficiency and cost savings in the manufacturing sector. The technology of the mineral industry is shaping the supply and demand of minerals derived materials. The composites are best classified as high performance materials have high strength-to-weight ratios, and require controlled manufacturing environments for optimum performance. Natural mineral garnet was used as the reinforcement of composite because of satisfactory mechanical properties as well as an attractive ecological alternative to others ceramics. For this purpose, samples have been prepared with different sizesof the garnet reinforcement using the mechanical stirring method to achieve the homogeneously dispersed strengthening phase. A systematic study of the effect of high contact pressure on the sliding wear behaviour of garnet reinforced LM13 alloy composites is presented in this paper. The SEM analysis of the worn samples and debris reveals the clues about the wear mechanism. The drastic improvement in the wear resistance of the composites at high contact pressure shows the high potential of the material to be used in engineering applications.

  10. Using piezo-electric material to simulate a vibration environment

    Science.gov (United States)

    Jepsen, Richard A.; Davie, Neil T.; Vangoethem, Douglas J.; Romero, Edward F.

    2010-12-14

    A target object can be vibrated using actuation that exploits the piezo-electric ("PE") property. Under combined conditions of vibration and centrifugal acceleration, a centrifugal load of the target object on PE vibration actuators can be reduced by using a counterweight that offsets the centrifugal loading. Target objects are also subjected to combinations of: spin, vibration, and acceleration; spin and vibration; and spin and acceleration.

  11. Nonlinear wave beams in a piezo semiconducting layer

    International Nuclear Information System (INIS)

    Bagdoev, A.G.; Shekoyan, A.V.; Danoyan, Z.N.

    1997-01-01

    The propagation of quasi-monochromatic nonlinear wave in a piezo semiconducting layer taking into account electron-concentration nonlinearity is considered. For such medium the evolution equations for incoming and reflected waves are derived. Nonlinear Schroedinger equations and solutions for narrow beams are obtained. It is shown that symmetry of incoming and reflected waves does not take place. The focusing of beams is investigated.18 refs

  12. Modeling startup and shutdown transient of the microlinear piezo drive via ANSYS

    Science.gov (United States)

    Azin, A. V.; Bogdanov, E. P.; Rikkonen, S. V.; Ponomarev, S. V.; Khramtsov, A. M.

    2017-02-01

    The article describes the construction-design of the micro linear piezo drive intended for a peripheral cord tensioner in the reflecting surface shape regulator system for large-sized transformable spacecraft antenna reflectors. The research target -the development method of modeling startup and shutdown transient of the micro linear piezo drive. This method is based on application software package ANSYS. The method embraces a detailed description of the calculation stages to determine the operating characteristics of the designed piezo drive. Based on the numerical solutions, the time characteristics of the designed piezo drive are determined.

  13. Mechanical regulation of stem-cell differentiation by the stretch-activated Piezo channel.

    Science.gov (United States)

    He, Li; Si, Guangwei; Huang, Jiuhong; Samuel, Aravinthan D T; Perrimon, Norbert

    2018-03-01

    Somatic stem cells constantly adjust their self-renewal and lineage commitment by integrating various environmental cues to maintain tissue homeostasis. Although numerous chemical and biological signals have been identified that regulate stem-cell behaviour, whether stem cells can directly sense mechanical signals in vivo remains unclear. Here we show that mechanical stress regulates stem-cell differentiation in the adult Drosophila midgut through the stretch-activated ion channel Piezo. We find that Piezo is specifically expressed in previously unidentified enteroendocrine precursor cells, which have reduced proliferation ability and are destined to become enteroendocrine cells. Loss of Piezo activity reduces the generation of enteroendocrine cells in the adult midgut. In addition, ectopic expression of Piezo in all stem cells triggers both cell proliferation and enteroendocrine cell differentiation. Both the Piezo mutant and overexpression phenotypes can be rescued by manipulation of cytosolic Ca 2+ levels, and increases in cytosolic Ca 2+ resemble the Piezo overexpression phenotype, suggesting that Piezo functions through Ca 2+ signalling. Further studies suggest that Ca 2+ signalling promotes stem-cell proliferation and differentiation through separate pathways. Finally, Piezo is required for both mechanical activation of stem cells in a gut expansion assay and the increase of cytosolic Ca 2+ in response to direct mechanical stimulus in a gut compression assay. Thus, our study demonstrates the existence of a specific group of stem cells in the fly midgut that can directly sense mechanical signals through Piezo.

  14. Piezo proteins are pore-forming subunits of mechanically activated channels.

    Science.gov (United States)

    Coste, Bertrand; Xiao, Bailong; Santos, Jose S; Syeda, Ruhma; Grandl, Jörg; Spencer, Kathryn S; Kim, Sung Eun; Schmidt, Manuela; Mathur, Jayanti; Dubin, Adrienne E; Montal, Mauricio; Patapoutian, Ardem

    2012-02-19

    Mechanotransduction has an important role in physiology. Biological processes including sensing touch and sound waves require as-yet-unidentified cation channels that detect pressure. Mouse Piezo1 (MmPiezo1) and MmPiezo2 (also called Fam38a and Fam38b, respectively) induce mechanically activated cationic currents in cells; however, it is unknown whether Piezo proteins are pore-forming ion channels or modulate ion channels. Here we show that Drosophila melanogaster Piezo (DmPiezo, also called CG8486) also induces mechanically activated currents in cells, but through channels with remarkably distinct pore properties including sensitivity to the pore blocker ruthenium red and single channel conductances. MmPiezo1 assembles as a ∼1.2-million-dalton homo-oligomer, with no evidence of other proteins in this complex. Purified MmPiezo1 reconstituted into asymmetric lipid bilayers and liposomes forms ruthenium-red-sensitive ion channels. These data demonstrate that Piezo proteins are an evolutionarily conserved ion channel family involved in mechanotransduction.

  15. Composite measures for profiling hospitals on bariatric surgery performance

    Science.gov (United States)

    Dimick, Justin B.; Birkmeyer, Nancy J.; Finks, Jonathan F.; Share, David A.; English, Wayne J.; Carlin, Arthur M.; Birkmeyer, John D.

    2014-01-01

    Objective We sought to develop a novel composite measure for profiling hospital performance with bariatric surgery. Design, Setting, and Patients Using clinical registry data from the Michigan Bariatric Surgery Collaborative (MBSC), we studied all patients undergoing bariatric surgery from 2008 to 2010. For gastric bypass surgery, we used empirical Bayes techniques to create a composite measure by combining several measures, including serious complications, reoperations, and readmissions; hospital and surgeon volume; and outcomes with other, related procedures. Hospitals were ranked based on 2008-09 and placed in one of 3 groups: 3-star (top third), 2-star (middle third), and 1-star (bottom third). We assessed how well these ratings predicted outcomes in the next year (2010), compared to other widely used measures. Main Outcome Measures Risk-adjusted serious complications. Results Composite measures explained a larger proportion of hospital-level variation in serious complication rates with gastric bypass than other measures. For example, the composite measure explained 89% of the variation compared to only 28% for risk-adjusted complication rates alone. Composite measures also appeared better at predicting future performance compared to individual measures. When ranked on the composite measure, 1-star hospitals (bottom 20%), had 2-fold higher serious complication rates (4.6% vs. 2.4%; OR 2.0; 95% CI, 1.1 to 3.5) compared to 3-star (top 20%) hospitals. Differences in serious complications rates between 1-star and 3-star hospitals were much smaller when hospitals were ranked using serious complications (4.0% vs. 2.7%; OR 1.6; 95% CI, 0.8-2.9) and hospital volume (3.3% vs. 3.2%; OR 0.85; 95% CI, 0.4 to 1.7) Conclusions Composite measures are much better at explaining hospital-level variation in serious complications and predicting future performance than other approaches. In this preliminary study, it appears that such composite measures may be better than existing

  16. High performance hydrophilic pervaporation composite membranes for water desalination

    KAUST Repository

    Liang, Bin

    2014-08-01

    A three-layer thin film nanofibrous pervaporation composite (TFNPVC) membrane was prepared by sequential deposition using electrospraying/electrospinning. The poly(vinyl alcohol) (PVA) top barrier layer was first electrosprayed on aluminum foil and its thickness can be easily controlled by adjusting the collecting time. Next a polyacrylonitrile (PAN) nanofibrous scaffold was deposited by electrospinning as a mid-layer support. A nonwoven PET layer is used to complete the composite membrane. The pervaporation desalination performance of TFNPVC membranes was tested using NaCl solutions at 100. Pa and at room temperature. The TFNPVC membranes show excellent desalination performance (high water flux and salt rejection >. 99.5%) for different salt concentrations with virtually no change in performance after 50. h of operation. © 2014 Elsevier B.V.

  17. Board Composition and Firm Performance: Evidence from Bangladesh

    Directory of Open Access Journals (Sweden)

    Afzalur Rashid

    2010-03-01

    Full Text Available This study examines the influence of corporate board composition in the form of representation of outsideindependent directors on firm economic performance in Bangladesh. Two hypotheses are developed toexamine the relationship among composition of board memberships including independent directors andfirm performance. An observation of 274 Bangladeshi firm-years is used in the study. A linear regressionanalysis is used to test the hypotheses. Results reveal that the outside (independent directors cannot addpotential value to the firm’s economic performance in Bangladesh. The idea of the introduction ofindependent directors may have benefits for greater transparency, but the non-consideration of theunderlying institutional and cultural differences in an emerging economy such as Bangladesh may not resultin economic value addition to the firm. The findings provide an insight to the regulators in their quest forharmonization of international corporate governance practices.

  18. A new dimension for piezo actuators: free-form out-of-plane displacement of single piezo layers

    International Nuclear Information System (INIS)

    Wapler, Matthias C; Brunne, Jens; Wallrabe, Ulrike

    2013-01-01

    We present a controlled mode of ‘topological’ displacement of homogeneous piezo films that arises solely from an inhomogeneous in-plane strain due to an inhomogeneous polarization. For the rotationally symmetric case, we develop a theoretical model that analytically relates the shape of the displacement to the polarization for the cases of in-plane and out-of-plane polarization. This is verified experimentally for several examples, and we further demonstrate controlled asymmetric deformations. (fast track communication)

  19. Detecting Liquefied Petroleum Gas (LPG) at Room Temperature Using ZnSnO3/ZnO Nanowire Piezo-Nanogenerator as Self-Powered Gas Sensor.

    Science.gov (United States)

    Fu, Yongming; Nie, Yuxin; Zhao, Yayu; Wang, Penglei; Xing, Lili; Zhang, Yan; Xue, Xinyu

    2015-05-20

    High sensitivity, selectivity, and reliability have been achieved from ZnSnO3/ZnO nanowire (NW) piezo-nanogenerator (NG) as self-powered gas sensor (SPGS) for detecting liquefied petroleum gas (LPG) at room temperature (RT). After being exposed to 8000 ppm LPG, the output piezo-voltage of ZnSnO3/ZnO NW SPGS under compressive deformation is 0.089 V, much smaller than that in air ambience (0.533 V). The sensitivity of the SPGS against 8000 ppm LPG is up to 83.23, and the low limit of detection is 600 ppm. The SPGS has lower sensitivity against H2S, H2, ethanol, methanol and saturated water vapor than LPG, indicating good selectivity for detecting LPG. After two months, the decline of the sensing performance is less than 6%. Such piezo-LPG sensing at RT can be ascribed to the new piezo-surface coupling effect of ZnSnO3/ZnO nanocomposites. The practical application of the device driven by human motion has also been simply demonstrated. This work provides a novel approach to fabricate RT-LPG sensors and promotes the development of self-powered sensing system.

  20. High-performance fiber/epoxy composite pressure vessels

    Science.gov (United States)

    Chiao, T. T.; Hamstad, M. A.; Jessop, E. S.; Toland, R. H.

    1978-01-01

    Activities described include: (1) determining the applicability of an ultrahigh-strength graphite fiber to composite pressure vessels; (2) defining the fatigue performance of thin-titanium-lined, high-strength graphite/epoxy pressure vessel; (3) selecting epoxy resin systems suitable for filament winding; (4) studying the fatigue life potential of Kevlar 49/epoxy pressure vessels; and (5) developing polymer liners for composite pressure vessels. Kevlar 49/epoxy and graphite fiber/epoxy pressure vessels, 10.2 cm in diameter, some with aluminum liners and some with alternation layers of rubber and polymer were fabricated. To determine liner performance, vessels were subjected to gas permeation tests, fatigue cycling, and burst tests, measuring composite performance, fatigue life, and leak rates. Both the metal and the rubber/polymer liner performed well. Proportionately larger pressure vessels (20.3 and 38 cm in diameter) were made and subjected to the same tests. In these larger vessels, line leakage problems with both liners developed the causes of the leaks were identified and some solutions to such liner problems are recommended.

  1. Post-impact performance of composites; Predicting Compression after Impact (CAI) in composite laminates

    NARCIS (Netherlands)

    Esrall, F.

    2013-01-01

    Impact damage has been known to seriously limit the performance of composite aircraft structures. In the preliminary design phase, tens of thousands of subparts need to be analyzed for impact. Over the years, many approaches have been proposed to study the creation of impact damage and to determine

  2. Performance of Syariah and Composite Indices: Evidence from Bursa Malaysia

    OpenAIRE

    Mohamed Albaity; Rubi Ahmad

    2008-01-01

    This study provides new evidence on the risk and return performance of the Kuala Lumpur Syariah Index (KLSI) and the Kuala Lumpur Composite Index (KLCI). An Islamic stock market index such as KLSI selects stocks according to Islamic laws, and thus has a more stringent screening process than its conventional counterpart, KLCI. Our results, however, provide no evidence of significant statistical differences in risk-adjusted returns between Islamic and conventional stock market indices during 19...

  3. Quickly updatable hologram images with high performance photorefractive polymer composites

    Science.gov (United States)

    Tsutsumi, Naoto; Kinashi, Kenji; Nonomura, Asato; Sakai, Wataru

    2012-02-01

    We present here quickly updatable hologram images using high performance photorefractive (PR) polymer composite based on poly(N-vinyl carbazole) (PVCz). PVCz is one of the pioneer materials for photoconductive polymer. PVCz/7- DCST/CzEPA/TNF (44/35/20/1 by wt) gives high diffraction efficiency of 68 % at E = 45 V/μm with fast response speed. Response speed of optical diffraction is the key parameter for real-time 3D holographic display. Key parameter for obtaining quickly updatable hologram images is to control the glass transition temperature lower enough to enhance chromophore orientation. Object image of the reflected coin surface recorded with reference beam at 532 nm (green beam) in the PR polymer composite is simultaneously reconstructed using a red probe beam at 642 nm. Instead of using coin object, object image produced by a computer was displayed on a spatial light modulator (SLM) is used as an object for hologram. Reflected object beam from a SLM interfered with reference beam on PR polymer composite to record a hologram and simultaneously reconstructed by a red probe beam. Movie produced in a computer was recorded as a realtime hologram in the PR polymer composite and simultaneously clearly reconstructed with a video rate.

  4. Thermal expansion behaviour of high performance PEEK matrix composites

    International Nuclear Information System (INIS)

    Goyal, R K; Mulik, U P; Tiwari, A N; Negi, Y S

    2008-01-01

    The thermal expansion behaviour of high performance poly(ether-ether-ketone) (PEEK) composites reinforced with micro- (8 μm) and nano- (39 nm) sized Al 2 O 3 particles was studied. The distribution of Al 2 O 3 in the PEEK matrix was studied by scanning electron microscopy and transmission electron microscopy. The coefficient of thermal expansion (CTE) was reduced from 58 x 10 -6 deg. C -1 for pure PEEK to 22 x 10 -6 deg. C -1 at 43 vol% micro-Al 2 O 3 and to 23 x 10 -6 deg. C -1 at 12 vol% nano-Al 2 O 3 composites. For a given volume fraction, nano-Al 2 O 3 particles are more effective in reducing the CTE of composites than that of micro-Al 2 O 3 particles. This may be attributed to the much higher interfacial area or volume of nanocomposites than that of microcomposites. The upper limit and lower limit of the Schapery model separately fit closely the CTE of the micro- and nano-composites, respectively. Other models such as the rule of mixture and Kerner and Turner models were also correlated with the data

  5. Association between Body Composition and Motor Performance in Preschool Children

    Directory of Open Access Journals (Sweden)

    Tanja H. Kakebeeke

    2017-09-01

    Full Text Available Objective: Being overweight makes physical movement more difficult. Our aim was to investigate the association between body composition and motor performance in preschool children. Methods: A total of 476 predominantly normal-weight preschool children (age 3.9 ± 0.7 years; m/f: 251/225; BMI 16.0 ± 1.4 kg/m2 participated in the Swiss Preschoolers' Health Study (SPLASHY. Body composition assessments included skinfold thickness, waist circumference (WC, and BMI. The Zurich Neuromotor Assessment (ZNA was used to assess gross and fine motor tasks. Results: After adjustment for age, sex, socioeconomic status, sociocultural characteristics, and physical activity (assessed with accelerometers, skinfold thickness and WC were both inversely correlated with jumping sideward (gross motor task β-coefficient -1.92, p = 0.027; and -3.34, p = 0.014, respectively, while BMI was positively correlated with running performance (gross motor task β-coefficient 9.12, p = 0.001. No significant associations were found between body composition measures and fine motor tasks. Conclusion: The inverse associations between skinfold thickness or WC and jumping sideward indicates that children with high fat mass may be less proficient in certain gross motor tasks. The positive association between BMI and running suggests that BMI might be an indicator of fat-free (i.e., muscle mass in predominately normal-weight preschool children.

  6. Integration of piezo-capacitive and piezo-electric nanoweb based pressure sensors for imaging of static and dynamic pressure distribution.

    Science.gov (United States)

    Jeong, Y J; Oh, T I; Woo, E J; Kim, K J

    2017-07-01

    Recently, highly flexible and soft pressure distribution imaging sensor is in great demand for tactile sensing, gait analysis, ubiquitous life-care based on activity recognition, and therapeutics. In this study, we integrate the piezo-capacitive and piezo-electric nanowebs with the conductive fabric sheets for detecting static and dynamic pressure distributions on a large sensing area. Electrical impedance tomography (EIT) and electric source imaging are applied for reconstructing pressure distribution images from measured current-voltage data on the boundary of the hybrid fabric sensor. We evaluated the piezo-capacitive nanoweb sensor, piezo-electric nanoweb sensor, and hybrid fabric sensor. The results show the feasibility of static and dynamic pressure distribution imaging from the boundary measurements of the fabric sensors.

  7. Koncepce tlačítkového piezo-generátoru

    OpenAIRE

    Kučera, David

    2012-01-01

    Tato bakalářská práce se zabývá koncepcí tlačítkového piezo-generátoru. V práci jsou popsány typy piezo-generátorů, vysvětlen piezoelektrický jev, typy piezoelektrických materiálů se zaměřením na piezokeramiku. Dále jsou popsány materiálové vlastnosti piezoelektrických keramik. Na konci práce je popsán návrh samotného tlačítkového piezo-generátoru. This bachelor’s thesis deals with proposal of piezo-generator inside button. There are described types of piezo-generators, explained piezoelec...

  8. Structural identification and damage diagnosis using self-sensing piezo-impedance transducers

    Science.gov (United States)

    Lim, Yee Yan; Bhalla, Suresh; Kiong Soh, Chee

    2006-08-01

    The use of smart materials, such as lead zirconate titanate (PZT), has accelerated developments in the fields of structural identification and automated structural health monitoring (SHM). One such technique that has made much progress is the electro-mechanical impedance (EMI) technique, which employs self-sensing piezo-impedance transducers. In this technique, a PZT patch is surface bonded to the structure to be monitored and its corresponding electro-mechanical admittance signature is used for damage detection. This paper introduces a new method for identifying structures from the measured admittance signatures in terms of equivalent structural parameters, whereby the identified parameters are used for damage characterization. The new method has been applied to a truss, a beam and a concrete cube, and found to be able to successfully perform structural identification and damage diagnosis. In addition, several advantages have been ascertained in comparison with the conventional, non-parametric statistical methods.

  9. Topology optimization of piezo modal transducers with null-polarity phases

    DEFF Research Database (Denmark)

    Donoso, A.; Sigmund, O.

    2016-01-01

    Piezo modal transducers in 2d can be designed theoretically by tailoring polarity of the surface electrodes. However, it is also necessary to include null-polarity phases of known width separating areas of opposite polarity in the manufacturing process in order to avoid short-circuiting. Otherwise...... the performance of such devices could be spoiled. In this work, we propose an appropriate topology optimization interpolation function for the electrode profile such that the effect of this new phase (hereafter gap-phase) is included in the formulation of the design problem. The approach is density-based, where...... the interface is controlled by including the gradient norm in the electrode profile interpolation. Through a detailed case study in 1d, conclusions on how to control the width of this gap-phase are extracted, and subsequently extended to the 2d case....

  10. A new piezo-driven microgripper based on the double-rocker mechanism

    International Nuclear Information System (INIS)

    Yang, Yi-ling; Wei, Yan-ding; Tian, Geng; Zhao, Xiao-wei; Fu, Lei; Lou, Jun-qiang

    2015-01-01

    This paper reports the design and modelling of a new piezo-driven microgripper with large output displacements. The design of the microgripper is based on the double-rocker mechanism and the parallelogram mechanism. The microgripper can produce a large output displacement and a parallel movement of the gripper tips. Theoretical models for the microgripper are derived using the pseudorigid-body-model method. Through several finite-element analysis simulations, the optimal geometric parameters of the microgripper are obtained, and the theoretical models are evaluated and verified. The performance of the proposed microgripper is demonstrated by several experiments, and a micromanipulation case is presented. The experimental results indicate that the microgripper with the double-rocker mechanism has a large output displacement of 213.9 μm and a large amplification ratio of 21.4. The microgripper is capable of multiscale micromanipulation. (paper)

  11. Metal matrix composite fabrication processes for high performance aerospace structures

    Science.gov (United States)

    Ponzi, C.

    A survey is conducted of extant methods of metal matrix composite (MMC) production in order to serve as a basis for prospective MMC users' selection of a matrix/reinforcement combination, cost-effective primary fabrication methods, and secondary fabrication techniques for the achievement of desired performance levels. Attention is given to the illustrative cases of structural fittings, control-surface connecting rods, hypersonic aircraft air inlet ramps, helicopter swash plates, and turbine rotor disks. Methods for technical and cost analysis modeling useful in process optimization are noted.

  12. Packaging of active fiber composites for improved sensor performance

    International Nuclear Information System (INIS)

    Melnykowycz, M; Barbezat, M; Koller, R; Brunner, A J

    2010-01-01

    Active fiber composites (AFC) composed of lead zirconate titanate (PZT) fibers embedded in an epoxy matrix and sandwiched between two interdigitated electrodes provide a thin and flexible smart material device which can act as a sensor or actuator. The thin profiles of AFC make them ideal for integration in glass or carbon fiber composite laminates. However, due to the low tensile limit of the PZT fibers, AFC can fail at strains below the tensile limit of many composites. This makes their use as a component in an active laminate design somewhat undesirable. In the current work, tensile testing of smart laminates composed of AFC integrated in glass fiber laminates was conducted to assess the effectiveness of different packaging strategies for improving AFC sensor performance at high strains relative to the tensile limit of the AFC. AFC were encased in carbon fiber, silicon, and pre-stressed carbon fiber to improve the tensile limit of the AFC when integrated in glass fiber laminates. By laminating AFC with pre-stressed carbon fiber, the tensile limit and strain sensor ability of the AFC were significantly improved. Acoustic emission monitoring was used and the results show that PZT fiber breakage was reduced due to the pre-stressed packaging process

  13. A Low Mass Translation Mechanism for Planetary FTIR Spectrometry using an Ultrasonic Piezo Linear Motor

    Science.gov (United States)

    Heverly, Matthew; Dougherty, Sean; Toon, Geoffrey; Soto, Alejandro; Blavier, Jean-Francois

    2004-01-01

    One of the key components of a Fourier Transform Infrared Spectrometer (FTIR) is the linear translation stage used to vary the optical path length between the two arms of the interferometer. This translation mechanism must produce extremely constant velocity motion across its entire range of travel to allow the instrument to attain high signal-to-noise ratio and spectral resolving power. A new spectrometer is being developed at the Jet Propulsion Laboratory under NASA s Planetary Instrument Definition and Development Program (PIDDP). The goal of this project is to build upon existing spaceborne FTIR spectrometer technology to produce a new instrument prototype that has drastically superior spectral resolution and substantially lower mass, making it feasible for planetary exploration. In order to achieve these goals, Alliance Spacesystems, Inc. (ASI) has developed a linear translation mechanism using a novel ultrasonic piezo linear motor in conjunction with a fully kinematic, fault tolerant linear rail system. The piezo motor provides extremely smooth motion, is inherently redundant, and is capable of producing unlimited travel. The kinematic rail uses spherical Vespel(R). rollers and bushings, which eliminates the need for wet lubrication, while providing a fault tolerant platform for smooth linear motion that will not bind under misalignment or structural deformation. This system can produce velocities from 10 - 100 mm/s with less than 1% velocity error over the entire 100-mm length of travel for a total mechanism mass of less than 850 grams. This system has performed over half a million strokes under vacuum without excessive wear or degradation in performance. This paper covers the design, development, and testing of this linear translation mechanism as part of the Planetary Atmosphere Occultation Spectrometer (PAOS) instrument prototype development program.

  14. Improving piezo actuators for nanopositioning tasks

    Science.gov (United States)

    Seeliger, Martin; Gramov, Vassil; Götz, Bernt

    2018-02-01

    In recent years, numerous applications emerged on the market with seemingly contradicting demands. On one side, the structure size decreased while on the other side, the overall sample size and speed of operation increased. Although the principle usage of piezoelectric positioning solutions has become a standard in the field of micro- and nanopositioning, surface inspection and manipulation, piezosystem jena now enhanced the performance beyond simple control loop tuning and actuator design. In automated manufacturing machines, a given signal has to be tracked fast and precise. However, control systems naturally decrease the ability to follow this signal in real time. piezosystem jena developed a new signal feed forward system bypassing the PID control. This way, we could reduce signal tracking errors by a factor of three compared to a conventionally optimized PID control. Of course, PID-values still have to be adjusted to specific conditions, e.g. changing additional mass, to optimize the performance. This can now be done with a new automatic tuning tool designed to analyze the current setup, find the best fitting configuration, and also gather and display theoretical as well as experimental performance data. Thus, the control quality of a mechanical setup can be improved within a few minutes without the need of external calibration equipment. Furthermore, new mechanical optimization techniques that focus not only on the positioning device, but also take the whole setup into account, prevent parasitic motion down to a few nanometers.

  15. Aligned Carbon Nanotubes for High-Performance Films and Composites

    Science.gov (United States)

    Zhang, Liwen

    Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or

  16. Piezopotential gated nanowire devices: Piezotronics and piezo-phototronics

    KAUST Repository

    Wang, Zhong Lin

    2010-12-01

    Due to the polarization of ions in a crystal that has non-central symmetry, a piezoelectric potential (piezopotential) is created in the crystal by applying a stress. For materials such as ZnO, GaN, and InN in the wurtzite structure family, the effect of piezopotential on the transport behavior of charge carriers is significant due to their multiple functionalities of piezoelectricity, semiconductor and photon excitation. By utilizing the advantages offered by these properties, a few new fields have been created. Electronics fabricated by using inner-crystal piezopotential as a "gate" voltage to tune/control the charge transport behavior is named piezotronics, with applications in strain/force/pressure triggered/controlled electronic devices, sensors and logic units. Piezo-phototronic effect is a result of three-way coupling among piezoelectricity, photonic excitation and semiconductor transport, which allows tuning and controlling of electro-optical processes by strain induced piezopotential. The objective of this review article is to introduce the fundamentals of piezotronics and piezo-phototronics and to give an updated progress about their applications in energy science and sensors. © 2010 Elsevier Ltd All rights reserved.

  17. Structure-based membrane dome mechanism for Piezo mechanosensitivity.

    Science.gov (United States)

    Guo, Yusong R; MacKinnon, Roderick

    2017-12-12

    Mechanosensitive ion channels convert external mechanical stimuli into electrochemical signals for critical processes including touch sensation, balance, and cardiovascular regulation. The best understood mechanosensitive channel, MscL, opens a wide pore, which accounts for mechanosensitive gating due to in-plane area expansion. Eukaryotic Piezo channels have a narrow pore and therefore must capture mechanical forces to control gating in another way. We present a cryo-EM structure of mouse Piezo1 in a closed conformation at 3.7Å-resolution. The channel is a triskelion with arms consisting of repeated arrays of 4-TM structural units surrounding a pore. Its shape deforms the membrane locally into a dome. We present a hypothesis in which the membrane deformation changes upon channel opening. Quantitatively, membrane tension will alter gating energetics in proportion to the change in projected area under the dome. This mechanism can account for highly sensitive mechanical gating in the setting of a narrow, cation-selective pore. © 2017, Guo et al.

  18. Mechanical performance of laminated composites incorporated with nanofibrous membranes

    International Nuclear Information System (INIS)

    Liu, L.; Huang, Z.-M.; He, C.L.; Han, X.J.

    2006-01-01

    The effect of non-woven nanofibrous membranes as interlaminar interfaces on the mechanical performance of laminated composites was investigated experimentally. The nanofibrous membranes are porous, thin and lightweight, and exhibit toughness and strength to some extent. They give little increase in weight and thickness when incorporated into a laminate. More important, they can be used as a functional agent carrier for the laminate. The nanofiber membranes used in this paper were prepared by electrospinning of Nylon-6 (PA6), Epoxy 609 (EPO 1691-410) and thermoplastic polyurethane (TPU), with a thickness ranging from 20 to 150 μm. The non-woven fabrics were attached to one side of a glass/epoxy fabric lamina prior to lamination and each fabric was arranged in between two adjacent plies of the laminate. The nanofibrous membranes were characterized through scanning electron microscopy (SEM) and tensile testing, whereas the mechanical properties of the laminate were understood in terms of three-point bending and short-beam shear tests. Results have shown that the nanofibrous membranes in the ply interfaces with a proper thickness did not affect the mechanical performance of the composite laminates significantly

  19. Enhancing Light Emission of ZnO-Nanofilm/Si-Micropillar Heterostructure Arrays by Piezo-Phototronic Effect.

    Science.gov (United States)

    Li, Xiaoyi; Chen, Mengxiao; Yu, Ruomeng; Zhang, Taiping; Song, Dongsheng; Liang, Renrong; Zhang, Qinglin; Cheng, Shaobo; Dong, Lin; Pan, Anlian; Wang, Zhong Lin; Zhu, Jing; Pan, Caofeng

    2015-06-22

    n-ZnO nanofilm/p-Si micropillar heterostructure light-emitting diode (LED) arrays for white light emissions are achieved and the light emission intensity of LED array is enhanced by 120% under -0.05% compressive strains. These results indicate a promising approach to fabricate Si-based light-emitting components with high performances enhanced by piezo-phototronic effect, with potential applications in touchpad technology, personalized signatures, smart skin, and silicon-based photonic integrated circuits. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Sleep Apnea Detection Based on Thoracic and Abdominal Movement Signals of Wearable Piezo-Electric Bands.

    Science.gov (United States)

    Lin, Yin-Yan; Wu, Hau-Tieng; Hsu, Chi-An; Huang, Po-Chiun; Huang, Yuan-Hao; Lo, Yu-Lun

    2016-12-07

    Physiologically, the thoracic (THO) and abdominal (ABD) movement signals, captured using wearable piezo-electric bands, provide information about various types of apnea, including central sleep apnea (CSA) and obstructive sleep apnea (OSA). However, the use of piezo-electric wearables in detecting sleep apnea events has been seldom explored in the literature. This study explored the possibility of identifying sleep apnea events, including OSA and CSA, by solely analyzing one or both the THO and ABD signals. An adaptive non-harmonic model was introduced to model the THO and ABD signals, which allows us to design features for sleep apnea events. To confirm the suitability of the extracted features, a support vector machine was applied to classify three categories - normal and hypopnea, OSA, and CSA. According to a database of 34 subjects, the overall classification accuracies were on average 75.9%±11.7% and 73.8%±4.4%, respectively, based on the cross validation. When the features determined from the THO and ABD signals were combined, the overall classification accuracy became 81.8%±9.4%. These features were applied for designing a state machine for online apnea event detection. Two event-byevent accuracy indices, S and I, were proposed for evaluating the performance of the state machine. For the same database, the S index was 84.01%±9.06%, and the I index was 77.21%±19.01%. The results indicate the considerable potential of applying the proposed algorithm to clinical examinations for both screening and homecare purposes.

  1. Predicting the dental implant stability based on the antiresonance phase of a piezo-based impedance sensor

    Directory of Open Access Journals (Sweden)

    Paramita Banerjee

    2017-01-01

    Full Text Available Background: The stability of dental implants (DIs in in vivo tests can be determined using noninvasive resonance frequency analysis technique. A low-cost piezo-based sensor has been developed for this purpose which uses a readily available two-terminal piezo element, to which a metal substrate is adhesively glued for attaching the implant. Aim: The attainment of implant stability in dynamic tests using this sensor must be standardized in terms of the major antiresonance (AR in the impedance phase responses using sensor-DI assembly. This will be used to predetermine the dimensions of the glued metal substrate in the sensor design. Materials and Methods: Multiple sensors with varying sensor dimensions were developed. Static and dynamic impedance studies were performed on these and corresponding sensor-implant assemblies. Static tests as well as in vitro tests with the sensor-implant assembly dipped in a standardized dental plaster mixture were performed in controlled laboratory conditions. Results: The probability of acceptance of the hypothesis has been checked using binomial distribution with a significance level of 5%. Statistically observed that for 95% of the cases where the DI becomes stable in dental plaster, both AR phase and AR frequency (ARF return to their corresponding static values. Furthermore, for a piezo element, whose ARF is within 6–6.6 kHz, the sensor yields maximal phase when the length of the metallic strip is 2 cm. Conclusions: Experimental validation supports both claims. Hence, this work can be extended to in vivo DI stability determination and design aspects of the corresponding sensor.

  2. Mechanical sensitivity of Piezo1 ion channels can be tuned by cellular membrane tension

    Science.gov (United States)

    Lewis, Amanda H; Grandl, Jörg

    2015-01-01

    Piezo1 ion channels mediate the conversion of mechanical forces into electrical signals and are critical for responsiveness to touch in metazoans. The apparent mechanical sensitivity of Piezo1 varies substantially across cellular environments, stimulating methods and protocols, raising the fundamental questions of what precise physical stimulus activates the channel and how its stimulus sensitivity is regulated. Here, we measured Piezo1 currents evoked by membrane stretch in three patch configurations, while simultaneously visualizing and measuring membrane geometry. Building on this approach, we developed protocols to minimize resting membrane curvature and tension prior to probing Piezo1 activity. We find that Piezo1 responds to lateral membrane tension with exquisite sensitivity as compared to other mechanically activated channels and that resting tension can drive channel inactivation, thereby tuning overall mechanical sensitivity of Piezo1. Our results explain how Piezo1 can function efficiently and with adaptable sensitivity as a sensor of mechanical stimulation in diverse cellular contexts. DOI: http://dx.doi.org/10.7554/eLife.12088.001 PMID:26646186

  3. Experimental characterization of a bi-dimensional array of negative capacitance piezo-patches for vibroacoustic control

    Science.gov (United States)

    Tateo, F.; Collet, M.; Ouisse, M.; Ichchou, M. N.; Cunefare, K. A.

    2013-04-01

    A recent technological revolution in the fields of integrated MEMS has finally rendered possible the mechanical integration of active smart materials, electronics and power supply systems for the next generation of smart composite structures. Using a bi-dimensional array of electromechanical transducers, composed by piezo-patches connected to a synthetic negative capacitance, it is possible to modify the dynamics of the underlying structure. In this study, we present an application of the Floquet-Bloch theorem for vibroacoustic power flow optimization, by means of distributed shunted piezoelectric material. In the context of periodically distributed damped 2D mechanical systems, this numerical approach allows one to compute the multi-modal waves dispersion curves into the entire first Brillouin zone. This approach also permits optimization of the piezoelectric shunting electrical impedance, which controls energy diffusion into the proposed semi-active distributed set of cells. Furthermore, we present experimental evidence that proves the effectiveness of the proposed control method. The experiment requires a rectangular metallic plate equipped with seventy-five piezo-patches, controlled independently by electronic circuits. More specifically, the out-of-plane displacements and the averaged kinetic energy of the controlled plate are compared in two different cases (open-circuit and controlled circuit). The resulting data clearly show how this proposed technique is able to damp and selectively reflect the incident waves.

  4. High performance bio-based thermosets for composites and coatings

    Science.gov (United States)

    Paramarta, Adlina Ambeg

    In the recent decade, there has been increasing interest in using renewable feedstocks as chemical commodities for composites and coatings application. Vegetable oils are promising renewable resources due to their wide availability with affordable cost. In fact, the utilization of vegetable oils to produce composite and coatings products has been around for centuries; linseed oil was widely used for wide variety of paints. However, due to its chemical structure, the application of vegetable oils for high-performance materials is limited; and thus chemical modification is necessary. One of the modification approaches is by substituting the glycerol core in the triglycerides with sucrose to form sucrose esters of vegetable oil fatty acids, in which this resin possesses a higher number of functional group per molecule and a more rigid core. In this research, thermosets of highly functionalized sucrose esters of vegetable oils were developed. Two crosslinking methods of epoxidized surcrose soyate (ESS) resins were explored: direct polymerization with anhydride moieties for composite applications and Michael-addition reaction of acrylated-epoxidized sucrose soyate (AESS) for coatings applications. In the first project, it was shown that the reaction kinetics, thermal and mechanical properties of the materials can be tuned by varying the molar ratio between the epoxide and anhydride, plus the type and amount of catalyst. Furthermore, the toughness properties of the ESS-based thermosets can be improved by changing the type of anhydride crosslinkers and incorporating secondary phase rubbers. Then, in the second system, the epoxy functionality in the ESS was converted into acrylate group, which then crosslinked with amine groups through the Michael-addition reaction to produce coatings systems. The high number of functional groups and the fast reactivity of the crosslinker results in coatings that can be cured at ambient temperature, yet still possess moderately high glass

  5. Timing performance of ZnO:Ga nanopowder composite scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Turtos, Rosana M. [Universita degli Studi di Milano-Bicocca, Milano (Italy); Gundacker, Stefan; Lucchini, Marco T.; Lecoq, Paul; Auffray, Etiennette [CERN, Geneva (Switzerland); Prochazkova, Lenka; Cuba, Vaclav [Czech Technical University, Faculty of Nuclear Sciences and Physical Engineering, Prague (Czech Republic); Buresova, Hana [Nuvia a.s, Kralupy nad Vltavou (Czech Republic); Mrazek, Jan [Institute of Photonics and Electronics AS CR, Prague (Czech Republic); Nikl, Martin [Institute of Physics of the AS CR, Prague (Czech Republic)

    2016-11-15

    The implementation of nanocrystal-based composite scintillators as a new generation of ultrafast particle detectors is explored using ZnO:Ga nanopowder. Samples are characterized with a spectral-time resolved photon counting system and pulsed X-rays, followed by coincidence time resolution (CTR) measurements under 511 keV gamma excitation. Results are comparable to CTR values obtained using bulk inorganic scintillators. Bringing the ZnO:Ga nanocrystal's timing performance to radiation detectors could pave the research path towards sub-20 ps time resolution as shown in this contribution. However, an efficiency boost when placing nanopowders in a transparent host constitutes the main challenge in order to benefit from sub-nanosecond recombination times. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Performance analysis of a composite dual-winding reluctance machine

    International Nuclear Information System (INIS)

    Anih, Linus U.; Obe, Emeka S.

    2009-01-01

    The electromagnetic energy conversion process of a composite dual-winding asynchronous reluctance machine is presented. The mechanism of torque production is explained using the magnetic fields distributions. The dynamic model developed in dq-rotor reference frame from first principles depicts the machine operation and response to sudden load change. The device is self-starting in the absence of rotor conductors and its starting current is lower than that of a conventional induction machine. Although the machine possesses salient pole rotors, it is clearly shown that its performance is that of an induction motor operating at half the synchronous speed. Hence the device produces synchronous torque while operating asynchronously. Simple tests were conducted on a prototype demonstration machine and the results obtained are seen to be in tune with the theory and the steady-state calculations.

  7. Fatigue Performance of Composite Laminates After Low-velocity Impact

    Directory of Open Access Journals (Sweden)

    LIANG Xiao-lin

    2016-12-01

    Full Text Available Compression-compression fatigue tests were carried out on T300/5405 composite laminates after low-velocity impact, compression performance of the laminates with different impact damages was studied together with its fatigue life and damage propagation under different stress levels, then the effects of impact energy, stress level and damage propagation on fatigue life of laminates were discussed. The results indicate that impact damage can greatly reduce the residual strength of laminates; under low fatigue load levels, the higher impact energy is, the shorter the fatigue life of laminates with impact damage will be; damage propagation undergoes two stages during the fatigue test, namely the steady propagation and the rapid propagation, accounting for 80% and 20% of the overall fatigue life, respectively; damage propagation rate decreases with the reduction of stress level.

  8. Performance ratio hardness characteristics polystyrene-metal composite materials

    International Nuclear Information System (INIS)

    Klepikov, V.F.; Prokhorenko, E.M.; Lytvynenko, V.V.; Zakharchenko, A.A.; Hazhmuradov, M.A.

    2015-01-01

    The methods of measuring the hardness of layered polystyrene-metallic composite materials. It is proposed to use powder-like tungsten and powder-like steel as radiation-protective layer. A measurement of the hardness of composites of different composition, and given its dependence on the particle size and their form. The possibility of increasing the hardness of the composites reinforced with metallic additives. Radiation-protective characteristics were calculated for the studied species of composite materials. Influence of the quantitative composition of the metal components is studied on the change of the absorbed dose of gamma radiation

  9. Mechanical performance of oil palm empty fruit bunches/jute fibres reinforced epoxy hybrid composites

    Energy Technology Data Exchange (ETDEWEB)

    Jawaid, M. [School of Industrial Technology, Universiti Sains Malaysia, 11800 Penang (Malaysia); Abdul Khalil, H.P.S., E-mail: akhalilhps@gmail.com [School of Industrial Technology, Universiti Sains Malaysia, 11800 Penang (Malaysia); Abu Bakar, A. [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia)

    2010-11-15

    Research highlights: {yields} Hybrid composites constituents of natural fibres show good mechanical performances. {yields} Hybridization with 20% jute fibre gives rise to sufficient modulus to composites. {yields} Outer or core material affect mechanical performance of hybrid composites. {yields} Impact strength of pure EFB composite is higher than hybrid composites. - Abstract: Oil palm empty fruit bunches (EFB)/jute fibre reinforced epoxy hybrid composites with different sequence of fibre mat arrangement such as EFB/jute/EFB and jute/EFB/jute were fabricated by hand lay-up method. The effect of layering patterns on the mechanical performance of the composites was studied. The hybrid composites are intended for engineering applications as an alternative to synthetic fibre composites. Mechanical performance of hybrid composites were evaluated and compared with the pure EFB, pure jute composites and neat epoxy using flexural and impact testing. The flexural properties of hybrid composite is higher than that of pure EFB composite with respect to the weight fraction of fibre, where as the impact strength of pure EFB composite is much higher than those of hybrid composites. The flexural results were interpreted using sandwich theory. The fracture surface morphology of the impact testing samples of the hybrid composites was performed by scanning electron microscopy (SEM).

  10. Mechanical performance of oil palm empty fruit bunches/jute fibres reinforced epoxy hybrid composites

    International Nuclear Information System (INIS)

    Jawaid, M.; Abdul Khalil, H.P.S.; Abu Bakar, A.

    2010-01-01

    Research highlights: → Hybrid composites constituents of natural fibres show good mechanical performances. → Hybridization with 20% jute fibre gives rise to sufficient modulus to composites. → Outer or core material affect mechanical performance of hybrid composites. → Impact strength of pure EFB composite is higher than hybrid composites. - Abstract: Oil palm empty fruit bunches (EFB)/jute fibre reinforced epoxy hybrid composites with different sequence of fibre mat arrangement such as EFB/jute/EFB and jute/EFB/jute were fabricated by hand lay-up method. The effect of layering patterns on the mechanical performance of the composites was studied. The hybrid composites are intended for engineering applications as an alternative to synthetic fibre composites. Mechanical performance of hybrid composites were evaluated and compared with the pure EFB, pure jute composites and neat epoxy using flexural and impact testing. The flexural properties of hybrid composite is higher than that of pure EFB composite with respect to the weight fraction of fibre, where as the impact strength of pure EFB composite is much higher than those of hybrid composites. The flexural results were interpreted using sandwich theory. The fracture surface morphology of the impact testing samples of the hybrid composites was performed by scanning electron microscopy (SEM).

  11. Improved passive shunt vibration control of smart piezo-elastic beams using modal piezoelectric transducers with shaped electrodes

    International Nuclear Information System (INIS)

    Vasques, C M A

    2012-01-01

    Modal control and spatial filtering technologies for mitigation of vibration and/or structural acoustics radiation may be achieved through the use of distributed modal piezoelectric transducers with properly shaped electrodes. This approach filters out undesirable and uncontrollable modes over the bandwidth of interest in order to increase the robustness and stability of the controlled structural system, and may also yield higher values of the generalized modal electromechanical coupling coefficient, which is an important design parameter for achieving efficient passive shunt damping design. In this paper the improvements in passive shunt damping performance when using modal piezoelectric transducers with shaped electrodes are investigated for a two-layered resonant-shunted piezo-elastic smart beam structure. An electromechanical one-dimensional equivalent single-layer Euler–Bernoulli analytical model of two-layered smart piezo-elastic beams with arbitrary spatially shaped electrodes is established for modal and uniform electrode designs. The model is verified and validated by comparison with a one-dimensional discrete-layer (layerwise) finite element model, the damping performance of the shunted smart beam with shaped electrodes is investigated and assessed in terms of the generalized electromechanical coupling coefficient and frequency responses obtained when considering uniform and modally shaped electrodes and the underlying improved performance and advantages are assessed and discussed. (paper)

  12. Piezo-Phototronic Effect on Selective Electron or Hole Transport through Depletion Region of Vis-NIR Broadband Photodiode.

    Science.gov (United States)

    Zou, Haiyang; Li, Xiaogan; Peng, Wenbo; Wu, Wenzhuo; Yu, Ruomeng; Wu, Changsheng; Ding, Wenbo; Hu, Fei; Liu, Ruiyuan; Zi, Yunlong; Wang, Zhong Lin

    2017-08-01

    Silicon underpins nearly all microelectronics today and will continue to do so for some decades to come. However, for silicon photonics, the indirect band gap of silicon and lack of adjustability severely limit its use in applications such as broadband photodiodes. Here, a high-performance p-Si/n-ZnO broadband photodiode working in a wide wavelength range from visible to near-infrared light with high sensitivity, fast response, and good stability is reported. The absorption of near-infrared wavelength light is significantly enhanced due to the nanostructured/textured top surface. The general performance of the broadband photodiodes can be further improved by the piezo-phototronic effect. The enhancement of responsivity can reach a maximum of 78% to 442 nm illumination, the linearity and saturation limit to 1060 nm light are also significantly increased by applying external strains. The photodiode is illuminated with different wavelength lights to selectively choose the photogenerated charge carriers (either electrons or holes) passing through the depletion region, to investigate the piezo-phototronic effect on electron or hole transport separately for the first time. This is essential for studying the basic principles in order to develop a full understanding about piezotronics and it also enables the development of the better performance of optoelectronics. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. High Performance High Temperature Thermoelectric Composites with Metallic Inclusions

    Science.gov (United States)

    Ma, James M. (Inventor); Bux, Sabah K. (Inventor); Fleurial, Jean-Pierre (Inventor); Ravi, Vilupanur A. (Inventor); Firdosy, Samad A. (Inventor); Star, Kurt (Inventor); Kaner, Richard B. (Inventor)

    2017-01-01

    The present invention provides a composite thermoelectric material. The composite thermoelectric material can include a semiconductor material comprising a rare earth metal. The atomic percent of the rare earth metal in the semiconductor material can be at least about 20%. The composite thermoelectric material can further include a metal forming metallic inclusions distributed throughout the semiconductor material. The present invention also provides a method of forming this composite thermoelectric material.

  14. Building Face Composites Can Harm Lineup Identification Performance

    Science.gov (United States)

    Wells, Gary L.; Charman, Steve D.; Olson, Elizabeth A.

    2005-01-01

    Face composite programs permit eyewitnesses to build likenesses of target faces by selecting facial features and combining them into an intact face. Research has shown that these composites are generally poor likenesses of the target face. Two experiments tested the proposition that this composite-building process could harm the builder's memory…

  15. Properties and performance of flax yarn/thermoplastic polyester composites

    DEFF Research Database (Denmark)

    Madsen, Bo; Mehmood, Shahid

    2012-01-01

    Aiming at demonstrating the potential of unidirectional natural fiber-reinforced thermoplastic composites in structural applications, textile flax yarn/thermoplastic polyester composites with variable fiber volume fractions have been manufactured by a filament-winding process followed by a vacuum......-assisted compression molding process. The microstructure of the composites shows that the flax fiber yarns are well impregnated by the polyester matrix, and this supports the measured low porosity content of the composites. The experimental tensile modulus and ultimate tensile stress of the composites in the axial...

  16. Measurement of absolute displacement-amplitude of ultrasonic wave using piezo-electric detection method

    Energy Technology Data Exchange (ETDEWEB)

    Park, Seong Hyun; Kim, Jong Beom; Jhang, Kyung Young [Hanyang University, Seoul (Korea, Republic of)

    2017-02-15

    A nonlinear ultrasonic parameter is defined by the ratio of displacement amplitude of the fundamental frequency component to that of the second-order harmonic frequency component. In this study, the ultrasonic displacement amplitude of an SUS316 specimen was measured via a piezo-electric-based method to identify the validity of piezo-electric detection method. For comparison, the ultrasonic displacement was also determined via a laser-based Fabry-Pérot interferometer. The experimental results for both measurements were in good agreement. Additionally, the stability of the repeated test results from the piezo-electric method exceeded that of the laser-interferometric method. This result indicated that the piezo-electric detection method can be utilized to measure a nonlinear ultrasonic parameter due to its excellent stability although it involves a complicated process.

  17. Portable bench tester for piezo weigh-in-motion equipment : final report, June 2006.

    Science.gov (United States)

    2006-06-01

    The Ohio Department of Transportation's (ODOT) piezo weigh-in-motion (WIM) equipment must be tested for initial working operation and to insure continued correct operation. Currently, the only available method to verify the vehicle classification par...

  18. Installation and evaluation of weigh-in-motion utilizing quartz-piezo sensor technology.

    Science.gov (United States)

    2016-06-28

    The objective of the research study was: to install a quartz-piezo based WIM system, and to : determine sensor survivability, accuracy and reliability under actual traffic conditions in : Connecticuts environment. If the systems prove dependable a...

  19. Portable bench tester for piezo weigh-in-motion equipment : executive summary report.

    Science.gov (United States)

    2006-06-01

    The Ohio Department of Transportation's (ODOT) piezo weigh-in-motion (WIM) equipment must be tested for initial working operation and to insure continued correct operation. Currently, the only available method to verify the vehicle classification par...

  20. Measurement of absolute displacement-amplitude of ultrasonic wave using piezo-electric detection method

    International Nuclear Information System (INIS)

    Park, Seong Hyun; Kim, Jong Beom; Jhang, Kyung Young

    2017-01-01

    A nonlinear ultrasonic parameter is defined by the ratio of displacement amplitude of the fundamental frequency component to that of the second-order harmonic frequency component. In this study, the ultrasonic displacement amplitude of an SUS316 specimen was measured via a piezo-electric-based method to identify the validity of piezo-electric detection method. For comparison, the ultrasonic displacement was also determined via a laser-based Fabry-Pérot interferometer. The experimental results for both measurements were in good agreement. Additionally, the stability of the repeated test results from the piezo-electric method exceeded that of the laser-interferometric method. This result indicated that the piezo-electric detection method can be utilized to measure a nonlinear ultrasonic parameter due to its excellent stability although it involves a complicated process

  1. The structure of a conserved Piezo channel domain reveals a novel beta sandwich fold

    Science.gov (United States)

    Kamajaya, Aron; Kaiser, Jens; Lee, Jonas; Reid, Michelle; Rees, Douglas C.

    2014-01-01

    Summary Piezo has recently been identified as a family of eukaryotic mechanosensitive channels composed of subunits containing over 2000 amino acids, without recognizable sequence similarity to other channels. Here, we present the crystal structure of a large, conserved extramembrane domain located just before the last predicted transmembrane helix of C. elegans PIEZO, which adopts a novel beta sandwich fold. The structure was also determined of a point mutation located on a conserved surface at the position equivalent to the human PIEZO1 mutation found in Dehydrated Hereditary Stomatocytosis (DHS) patients (M2225R). While the point mutation does not change the overall domain structure, it does alter the surface electrostatic potential that may perturb interactions with a yet-to-be identified ligand or protein. The lack of structural similarity between this domain and any previously characterized fold, including those of eukaryotic and bacterial channels, highlights the distinctive nature of the Piezo family of eukaryotic mechanosensitive channels. PMID:25242456

  2. Novel yellow colored flame compositions with superior spectral performance

    Directory of Open Access Journals (Sweden)

    Ramy Sadek

    2017-02-01

    Full Text Available The production of colored flames is the primary purpose of military signaling, projectile tracing, and illuminating devices. Certain elements and compounds when heated to high temperature have the unique property of emitting lines or narrow bands in the visible region (380–780 nm. This study, reports on the development of novel yellow colored flame compositions with enhanced spectral performance in terms of luminous intensity, and color quality to standard Russian yellow tracer. The light intensity and the imprint spectra of developed yellow flares were measured using digital luxmeter and UV–Vis. spectrometer respectively. The main giving of this study is that the light intensity, and color quality of Russian yellow tracer were improved by 287%, and 170% respectively. This was accomplished by means of optimizing the ratio of novel binder to color source using aluminum metal fuel. Aluminum-based formulations were found to maximize the formation of yellow reactive emitting specimens, and to eliminate any interfering incandescent emission resulted from MgO. Quantification of yellow color emitting specimens in the combustion gaseous products was achieved using chemical equilibrium thermodynamic code named ICT (Institute of Chemical Technology in Germany, Virgin 2008; in an attempt to judge the light quality. This improvement in yellow flare performance established the rule that the emission intensity increases as the reaction temperature increases. In the meantime upper limit of temperature was avoided to maximize the color quality.

  3. Vegetation composition and structure significantly influence green roof performance

    Energy Technology Data Exchange (ETDEWEB)

    Dunnett, N.; Nagase, A.; Booth, R.; Grime, P. [Sheffield Univ., Sheffield (United Kingdom). Dept. of Landscape Architecture

    2005-07-01

    The majority of published literature on green roofs contains little specific information on the contribution of plants to the various functions and properties of green roofs. This paper reviewed previously published material in an attempt to shed light on the role of vegetation composition in green roof systems, with specific reference to hydrology and biodiversity support. Two ongoing experiments at the University of Sheffield were then considered: (1) a comparison of quality and quantity of runoff from different types of vegetation; and (2) a comparison of flowering seasons and biodiversity support of different vegetation. Results of the studies showed that there was no general pattern of variation in runoff that could be related to vegetation complexity or taxonomic composition of the communities. During the winter months, high precipitation quickly saturated the soil and percolate losses were similar for all treatments. In the summer, throughflow losses differed between treatments in relation to the structure of the plant canopy. Differing mechanisms resulted in variations in the volume of percolate that was collected. Lower volumes of percolate were observed in herb-only monocultures of Leontdon hispidus, a species with a high water content. Tap-rooted species were seen to more effectively absorb soil moisture. The biodiversity support study focused on the study of Sedum species and Labiatae species, which suggested that mixed vegetation containing these species had a far greater likelihood of attracting wild bees to support pollination. Results of the studies indicated that green roof vegetation with greater structural and species diversity may provide different benefits than sedum-dominated roots. Further studies are needed to investigate the trade-offs between vegetation types, and green roof functions and performance in order to justify calls for a wider diversity of green roof types. 8 refs., 2 tabs., 1 fig.

  4. Role of Piezo Channels in Ultrasound-stimulated Dental Stem Cells.

    Science.gov (United States)

    Gao, Qianhua; Cooper, Paul R; Walmsley, A Damien; Scheven, Ben A

    2017-07-01

    Piezo1 and Piezo2 are mechanosensitive membrane ion channels. We hypothesized that Piezo proteins may play a role in transducing ultrasound-associated mechanical signals and activate downstream mitogen-activated protein kinase (MAPK) signaling processes in dental cells. In this study, the expression and role of Piezo channels were investigated in dental pulp stem cells (DPSCs) and periodontal ligament stem cells (PDLSCs) after treatment with low-intensity pulsed ultrasound (LIPUS). Cell proliferation was evaluated by bromodeoxyuridine incorporation. Western blots were used to analyze the proliferating cell nuclear antigen as well as the transcription factors c-fos and c-jun. Enzyme-linked immunosorbent assay and Western blotting were used to determine the activation of MAPK after LIPUS treatment. Ruthenium red (RR), a Piezo ion channel blocker, was applied to determine the functional role of Piezo proteins in LIPUS-stimulated cell proliferation and MAPK signaling. Western blotting showed the presence of Piezo1 and Piezo2 in both dental cell types. LIPUS treatment significantly increased the level of the Piezo proteins in DPSCs after 24 hours; however, no significant effects were observed in PDLSCs. Treatment with RR significantly inhibited LIPUS-stimulated DPSC proliferation but not PDLSC proliferation. Extracellular signal-related kinase (ERK) 1/2 MAPK was consistently activated in DPSCs over a 24-hour time period after LIPUS exposure, whereas phosphorylated c-Jun N-terminal kinase and p38 mitogen-activated protein kinase MAPK were mainly increased in PDLSCs. RR affected MAPK signaling in both dental cell types with its most prominent effects on ERK1/2/MAPK phosphorylation levels; the significant inhibition of LIPUS-induced stimulation of ERK1/2 activation in DPSCs by RR suggests that stimulation of DPSC proliferation by LIPUS involves Piezo-mediated regulation of ERK1/2 MAPK signaling. This study for the first time supports the role of Piezo ion channels in

  5. A Study on the Optimal Actuation Structure Design of a Direct Needle-Driven Piezo Injector for a CRDi Engine

    Directory of Open Access Journals (Sweden)

    Sangik Han

    2017-03-01

    Full Text Available Recently, the high-pressure fuel injection performance of common-rail direct injection (CRDi engines has become more important, due to the need to improve the multi-injection strategy. A multiple injection strategy provides better emission and fuel economy characteristics than a normal single injection scheme. The CRDi engine performance changes with the type of high-pressure electro-mechanical injector that is used and its injection response in a multi-injection scheme. In this study, a direct needle-driven piezo injector (DPI was investigated, to optimize its actuation components, including the plate length, number of springs, and the elasticity of the spring between the injector needle and the piezo stack. Three prototype DPIs were proposed by this research. They were classified as Type 1, 2, and 3, depending on whether the injector needle was hydraulic or mechanical. Then, the optimal prototype was determined by conducting four evaluation experiments analyzing the maximum injection pressure, injection rate, spray visualization, and real engine combustion application. As a result, it was found that the Type 3 DPI prototype, with several pan-springs and plates, had the highest injection pressure, a steady injection rate, and the fastest spray speed. It also demonstrated the most effective emission reduction for a two-stage rapid spray injection in a single-cylinder CRDi engine. The Type 3 DPI displays an increased elasticity from its hydraulic needle that provides a synergy effect for improving DPI actuation.

  6. Merkel cells and Meissner's corpuscles in human digital skin display Piezo2 immunoreactivity.

    Science.gov (United States)

    García-Mesa, Y; García-Piqueras, J; García, B; Feito, J; Cabo, R; Cobo, J; Vega, J A; García-Suárez, O

    2017-12-01

    The transformation of mechanical energy into electrical signals is the first step in mechanotransduction in the peripheral sensory nervous system and relies on the presence of mechanically gated ion channels within specialized sensory organs called mechanoreceptors. Piezo2 is a vertebrate stretch-gated ion channel necessary for mechanosensitive channels in mammalian cells. Functionally, it is related to light touch, which has been detected in murine cutaneous Merkel cell-neurite complexes, Meissner-like corpuscles and lanceolate nerve endings. To the best of our knowledge, the occurrence of Piezo2 in human cutaneous mechanoreceptors has never been investigated. Here, we used simple and double immunohistochemistry to investigate the occurrence of Piezo2 in human digital glabrous skin. Piezo2 immunoreactivity was detected in approximately 80% of morphologically and immunohistochemically characterized (cytokeratin 20 + , chromogranin A + and synaptophisin + ) Merkel cells. Most of them were in close contact with Piezo2 - nerve fibre profiles. Moreover, the axon, but not the lamellar cells, of Meissner's corpuscles was also Piezo2 + , but other mechanoreceptors, i.e. Pacinian or Ruffini's corpuscles, were devoid of immunoreactivity. Piezo2 was also observed in non-nervous tissue, especially the basal keratinocytes, endothelial cells and sweat glands. The present results demonstrate the occurrence of Piezo2 in cutaneous sensory nerve formations that functionally work as slowly adapting (Merkel cells) and rapidly adapting (Meissner's corpuscles) low-threshold mechanoreceptors and are related to fine and discriminative touch but not to vibration or hard touch. These data offer additional insight into the molecular basis of mechanosensing in humans. © 2017 Anatomical Society.

  7. Pyrotechnic countermeasures: IV. Radiometric performance of a sulphur-based Flare composition

    Energy Technology Data Exchange (ETDEWEB)

    Koch, Ernst-Christian [NATO Munitions Safety Information Analysis Center (MSIAC), Brussels (Belgium)

    2008-10-15

    Radiometric performance of a sulphur-based flare composition has been investigated. Composition comprising sulphur, potassium perchlorate and antimony sulphide has acceptable band ratio but an order of magnitude weaker spectral efficiency than typical carbon-based compositions. The use of other sulphur compounds with potential for increased performance is discussed. For part III see Ref. [1]. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  8. Activation of TRPV1 channels inhibits mechanosensitive Piezo channel activity by depleting membrane phosphoinositides

    Science.gov (United States)

    Borbiro, Istvan; Badheka, Doreen; Rohacs, Tibor

    2015-01-01

    Capsaicin is an activator of the heat-sensitive TRPV1 (transient receptor potential vanilloid 1) ion channels and has been used as a local analgesic. We found that activation of TRPV1 channels with capsaicin either in dorsal root ganglion neurons or in a heterologous expression system inhibited the mechanosensitive Piezo1 and Piezo2 channels by depleting phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] and its precursor PI(4)P from the plasma membrane through Ca2+-induced phospholipase Cδ (PLCδ) activation. Experiments with chemically inducible phosphoinositide phosphatases and receptor-induced activation of PLCβ indicated that inhibition of Piezo channels required depletion of both PI(4)P and PI(4,5)P2. The mechanically activated current amplitudes decreased substantially in the excised inside-out configuration, where the membrane patch containing Piezo1 channels is removed from the cell. PI(4,5)P2 and PI(4)P applied to these excised patches inhibited this decrease. Thus, we concluded that Piezo channel activity requires the presence of phosphoinositides, and the combined depletion of PI(4,5)P2 or PI(4)P reduces channel activity. In addition to revealing a role for distinct membrane lipids in mechanosensitive ion channel regulation, these data suggest that inhibition of Piezo2 channels may contribute to the analgesic effect of capsaicin. PMID:25670203

  9. Bonding performance of self-adhesive flowable composites to enamel, dentin and a nano-hybrid composite.

    Science.gov (United States)

    Peterson, Jana; Rizk, Marta; Hoch, Monika; Wiegand, Annette

    2018-04-01

    This study aimed to analyze bond strengths of self-adhesive flowable composites on enamel, dentin and nano-hybrid composite. Enamel, dentin and nano-hybrid composite (Venus Diamond, Heraeus Kulzer, Germany) specimens were prepared. Three self-adhesive composites (Constic, DMG, Germany; Fusio Liquid Dentin, Pentron Clinical, USA; Vertise Flow, Kerr Dental, Italy) or a conventional flowable composite (Venus Diamond Flow, Heraeus Kulzer, Germany, etch&rinse technique) were applied to enamel and dentin. Nano-hybrid composite specimens were initially aged by thermal cycling (5000 cycles, 5-55 °C). Surfaces were left untreated or pretreated by mechanical roughening, Al 2 O 3 air abrasion or silica coating/silanization. In half of the composite specimens, an adhesive (Optibond FL, Kerr Dental, Italy) was used prior to the application of the flowable composites. Following thermal cycling (5000 cycles, 5-55 °C) of all specimens, shear bond strengths (SBS) and failure modes were analyzed (each subgroup n = 16). Statistical analysis was performed by ANOVAs/Bonferroni post hoc tests, Weibull statistics and χ 2 -tests (p composites on enamel and dentin were significantly lower (enamel: composite (enamel: 13.0 ± 5.1, dentin: 11.2 ± 6.3), and merely adhesive failures could be observed. On the nano-hybrid composite, SBS were significantly related to the pretreatment. Adhesive application improved SBS of the conventional, but not of the self-adhesive composites. The self-adhesive composite groups showed less cohesive failures than the reference group; the occurence of cohesive failures increased after surface pretreatment. Bonding of self-adhesive flowable composites to enamel and dentin is lower than bonding to a nano-hybrid composite.

  10. Structures and Performance of Graphene/Polyimide Composite Graphite Fibers

    Directory of Open Access Journals (Sweden)

    LI Na

    2017-09-01

    Full Text Available Dry-wet spinning process was used to gain graphene oxide/polyimide composite fibers, then graphene/polyimide composite carbon and graphite fibers were obtained through carbonized and graphitized. Different graphene oxide contents of the composite carbon and graphite fibers were measured by thermal gravimetric analysis, Raman, mechanical properties, electrical properties,SEM and so on. The results show that when the GO content is 0.3%(mass fraction,the same below, the thermal property of the graphene oxide/polyimide composite fibers is the best. The mechanical and electrical properties are obriously improved by the addition of GO, graphitization degree also increases. When the composite carbon fibers are treated at 2800℃, GO content increases to 2.0%, the thermal conductivity of the composite graphite fibers reaches 435.57W·m-1·K-1 and cross-section structures of carbon fibers are more compact.

  11. Improvement of performance of ultra-high performance concrete based composite material added with nano materials

    Directory of Open Access Journals (Sweden)

    Pang Jinchang

    2016-03-01

    Full Text Available Ultra-high performance concrete (UHPC, a kind of composite material characterized by ultra high strength, high toughness and high durability. It has a wide application prospect in engineering practice. But there are some defects in concrete. How to improve strength and toughness of UHPC remains to be the target of researchers. To obtain UHPC with better performance, this study introduced nano-SiO2 and nano-CaCO3 into UHPC. Moreover, hydration heat analysis, X-Ray Diffraction (XRD, mercury intrusion porosimetry (MIP and nanoindentation tests were used to explore hydration process and microstructure. Double-doped nanomaterials can further enhance various mechanical performances of materials. Nano-SiO2 can promote early progress of cement hydration due to its high reaction activity and C-S-H gel generates when it reacts with cement hydration product Ca(OH2. Nano-CaCO3 mainly plays the role of crystal nucleus effect and filling effect. Under the combined action of the two, the composite structure is denser, which provides a way to improve the performance of UHPC in practical engineering.

  12. PIEZO channel protein naturally expressed in human breast cancer cell MDA-MB-231 as probed by atomic force microscopy

    Science.gov (United States)

    Weng, Yuanqi; Yan, Fei; Chen, Runkang; Qian, Ming; Ou, Yun; Xie, Shuhong; Zheng, Hairong; Li, Jiangyu

    2018-05-01

    Mechanical stimuli drives many physiological processes through mechanically activated channels, and the recent discovery of PIEZO channel has generated great interests in its mechanotransduction. Many previous researches investigated PIEZO proteins by transcribing them in cells that originally have no response to mechanical stimulation, or by forming PIEZO-combined complexes in vitro, and few studied PIEZO protein's natural characteristics in cells. In this study we show that MDA-MB-231, a malignant cell in human breast cancer cell line, expresses the mechanosensitive behavior of PIEZO in nature without extra treatment, and we report its characteristics in response to localized mechanical stimulation under an atomic force microscope, wherein a correlation between the force magnitude applied and the channel opening probability is observed. The results on PIEZO of MDA-MB-231 can help establish a basis of preventing and controlling of human breast cancer cell via mechanical forces.

  13. Performance of patch repaired composite panels under fatigue loads

    International Nuclear Information System (INIS)

    Darwish, Feras H.; Hamoush, S.; Shivakumar, K.

    2006-01-01

    This paper evaluates the performance of bonded patch-scarf repairs of full scale laminated composite panels under cyclic load conditions. Nondestructive testing to characterize the quality of repairs and destructive testing to evaluate the performance of repaired panels were used in this study. Carbon/Epoxy prepreg material used was used to lay up six-ply (12 in. x 27 in. /305x686mm) (-60/60/0) s quasi-isotropic laminates. 7-ply scarf repair with a gradient of 0.5 inch (12.7mm) per layer was used to perform the repair of a damaged zone. The patch consisted of 7.5 inches (190mm) diameter adhesive film, 1 inch (25.4mm) diameter filler ply at 90fiber orientation, and six plies (2-7 inches (51-178mm) diameter) to match the lay-up of the parent material. The study was extended to include defective repairs. The defect was engineered by inserting a 1 inch (25.4 mm) circular Teflon flaw between the fifth and sixth layers of the patch. A total of 28 panels were prepared and divided into five categories: (1) three pristine panels (undamaged parental materials); (2) three damaged panels (1-inch-centered-hole); (3) two repaired panels with wrong fiber orientation; (4) nine good repaired panels, and (5) eleven defective repair panels (1 inch flaw). A nondestructive evaluation to check the conditions of the repairs was performed on most of the tested panels that include the pulse-echo C-scan and pseudo through transmission air coupled and water coupled C-scan. Based on the results of the experimental evaluation of this study, good repair restored 95% of the tensile strength while defective repair restored 90% of the tensile strength of the pristine panels. Under fatigue loading, panels repaired with a 1 inch delamination flaw within the patch layers showed a major reduction in fatigue life compared to the good repair panels under similar loading conditions. (author)

  14. PERFORMANCE EVALUATION OF CEILING RADIANT COOLING SYSTEM IN COMPOSITE CLIMATE

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Anuj [Malaviya National Institute of Technology (MNIT), Jaipur, India; Mathur, Jyotirmay [Malaviya National Institute of Technology (MNIT), Jaipur, India; Bhandari, Mahabir S [ORNL

    2015-01-01

    Radiant cooling systems are proving to be an energy efficient solution due to higher thermal capacity of cooling fluid especially for the buildings that require individual zone controls and where the latent loads are moderate. The Conventional air conditioners work at very low temperature i.e.5-8 c (refrigerant evaporator inlet) while the radiant cooling systems, also referred as high temperature cooling system, work at high temperatures i.e. 14-18 c. The radiant cooling systems can maintain lower MRT (Mean Radiant Temperature) as ceiling panels maintain uniform temperature gradient inside room and provide higher human comfort. The radiant cooling systems are relatively new systems and their operation and energy savings potential are not quantified for a large number of buildings and operational parameters. Moreover, there are only limited numbers of whole building simulation studies have been carried out for these systems to have a full confidence in the capability of modelling tools to simulate these systems and predict the impact of various operating parameters. Theoretically, savings achieve due to higher temperature set point of chilled water, which reduces chiller-running time. However, conventional air conditioner runs continuously to maintain requisite temperature. In this paper, experimental study for performance evaluation of radiant cooling system carried out on system installed at Malaviya National Institute of Technology Jaipur. This paper quantifies the energy savings opportunities and effective temperature by radiant cooling system at different chilled water flow rates and temperature range. The data collected/ analysed through experimental study will used for calibration and validation of system model of building prepared in building performance simulation software. This validated model used for exploring optimized combinations of key parameters for composite climate. These optimized combinations will used in formulation of radiant cooling system

  15. Composition

    DEFF Research Database (Denmark)

    Bergstrøm-Nielsen, Carl

    2014-01-01

    Cue Rondo is an open composition to be realised by improvising musicians. See more about my composition practise in the entry "Composition - General Introduction". Caution: streaming the sound/video files will in some cases only provide a few minutes' sample, or the visuals will not appear at all....... Please DOWNLOAD them to see/hear them in full length! This work is licensed under a Creative Commons "by-nc" License. You may for non-commercial purposes use and distribute it, performance instructions as well as specially designated recordings, as long as the author is mentioned. Please see http...

  16. Resistance Welding of Thermoplastic Composites : Process and Performance

    NARCIS (Netherlands)

    Shi, H.

    2014-01-01

    Compared to thermoset composites, thermoplastic composites are drawing more and more attention by aircraft industries not only due to their excellent material properties but also due to their potentials to reduce cycle time and structure cost by using low-cost manufacturing technologies such as

  17. Advanced wood- and bio-composites : enhanced performance and sustainability

    Science.gov (United States)

    Jerrold E. Winandy

    2006-01-01

    Use of wood-based-composites technology to create value-added commodities and traditional construction materials is generally accepted worldwide. Engineered wood- and lignocellulosic-composite technologies allow users to add considerable value to a diverse number of wood- and lignocellulosic feedstocks including small-diameter timber, fast plantation-grown timber,...

  18. Do Nanofilled/Nanohybrid Composites Allow for Better Clinical Performance of Direct Restorations Than Traditional Microhybrid Composites? A Systematic Review.

    Science.gov (United States)

    Angerame, D; De Biasi, M

    2018-03-23

    This systematic review was carried out to assess the clinical effectiveness of nanofilled and nanohybrid composites used for direct restorations in comparison with microhybrid composites. The guidelines for the preferred reporting items for systematic reviews and meta-analyses were followed. A search of articles published from July 1996 to February 2017 was performed in PubMed, SciVerse Scopus, Latin American and Caribbean Health Sciences, the Scientific Electronic Library Online, and the Cochrane Library. The present review selected only randomized controlled trials comparing the clinical performance of a nanofilled or nanohybrid composite for direct restorations with that of a microhybrid composite. The research found 201 studies. Twenty-one articles fulfilled the criteria of the present review. However, the included studies were characterized by great methodological diversities. As a general trend, nanofilled and nanohybrid composites were found to be capable of clinical performance, marginal quality, and resistance to wear similar to that of traditional composites without showing improved surface characteristics. The risk of bias of included studies was judged unclear or high. The clinical performance of nanofilled/nanohybrid composites was found to be comparable to that of traditional composites in the posterior area. The data concerning anterior and cervical restorations were insufficient. With regard to the esthetic properties, there is a compelling need for studies on anterior teeth in which the operators are kept unaware of the restorative material. Nanofilled/nanohybrid composites seem to be a valid alternative to traditional microhybrid composites, and at the moment, there is low-level evidence attesting a lack of their superiority.

  19. Test of piezo-ceramic motor technology in ITER relevant high magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Monti, Chiara, E-mail: chiara.monti@enea.it [Associazione EURATOM-ENEA sulla Fusione, via Enrico Fermi 45, 00044 Frascati, Rome (Italy); Besi Vetrella, Ugo; Mugnaini, Giampiero; Neri, Carlo; Rossi, Paolo; Viola, Rosario [Associazione EURATOM-ENEA sulla Fusione, via Enrico Fermi 45, 00044 Frascati, Rome (Italy); Dubus, Gregory; Damiani, Carlo [Fusion for Energy, c/ Josep Pla, 2 Torres Diagonal Litoral, 08019 Barcelona (Spain)

    2014-10-15

    In the framework of a Fusion for Energy (F4E) grant, a test campaign started in 2012 in order to assess the performance of the in-vessel viewing system (IVVS) probe concept and to verify its compatibility when exposed to ITER typical working conditions. ENEA laboratories went through with several tests simulating high magnetic fields, high temperature, high vacuum, gamma radiation and neutron radiation. A customized motor has been adopted to study the performances of ultrasonic piezo motors technology in high magnetic field conditions. This paper reports on the testing activity performed on the motor in a multi Tesla magnetic field. The job was carried out in a test facility of ENEA laboratories able to achieve 14 T. A maximum field of 10 T, fully compliant with ITER requirements (8 T), was applied. A specific mechanical assembly has been designed and manufactured to hold the motor in the region with high homogeneity of the field. Results obtained so far indicate that the motor is compatible with high magnetic fields, and are presented in the paper.

  20. TIPPtool: Compositional Specification and Analysis of Markovian Performance Models

    NARCIS (Netherlands)

    Hermanns, H.; Halbwachs, N.; Peled, D.; Mertsiotakis, V.; Siegle, M.

    1999-01-01

    In this short paper we briefly describe a tool which is based on a Markovian stochastic process algebra. The tool offers both model specification and quantitative model analysis in a compositional fashion, wrapped in a userfriendly graphical front-end.

  1. Cracking and impact performance characteristics of plastic composite ties.

    Science.gov (United States)

    2012-03-01

    As followup to a workshop on Engineered Composite Ties sponsored by the American Railway Engineering and Maintenance-of-Way Association and the Federal Railroad Administration, the Transportation Technology Center, Inc., in Pueblo, CO, conducted a se...

  2. The Effect of Training Data Set Composition on the Performance of a Neural Image Caption Generator

    Science.gov (United States)

    2017-09-01

    REPORT TYPE Technical Report 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE The Effect of Training Data Set Composition on the Performance of a...ARL-TR-8124 ● SEP 2017 US Army Research Laboratory The Effect of Training Data Set Composition on the Performance of a Neural...Laboratory The Effect of Training Data Set Composition on the Performance of a Neural Image Caption Generator by Abigail Wilson Montgomery Blair

  3. Performance of waste-paper/PETG wood–plastic composites

    Directory of Open Access Journals (Sweden)

    Lijie Huang

    2018-05-01

    Full Text Available Wood–plastic composites were prepared from polyethylene terephthalate- 1,4-cyclohexanedimethanol ester (PETG and waste-paper fiber that was unmodified, modified with alkyl-ketene-dimer (AKD, and modified with a silane-coupling agent. The mechanical properties, water absorption properties, surface structure, and thermal properties of the three prepared materials were compared. The results showed that the optimum amount of waste-paper powder is 10 wt%, while that of the waste-paper particles is 60–80 mesh. The use of AKD and coupling agent KH550 can reduce the water absorption of the composite; however, the reductive effect of the coupling agent is better, in that it is reduced by 0.3%. Modification using a 1-wt% KH550 coupling agent can effectively increase the tensile strength of a composite from 31.36 to 41.67 MPa (increase of 32.8%, while the bending strength increased from 86.47 to 98.31 MPa (increase of 13.7%. This also enhances the thermal stability of the composites. With the addition of the coupling agent, the composite material maintains good mechanical properties even after being immersed in water; this can enable the safe use of these composite materials in outdoor environments.

  4. Performance of waste-paper/PETG wood–plastic composites

    Science.gov (United States)

    Huang, Lijie; An, Shuxiang; Li, Chunying; Huang, Chongxing; Wang, Shuangfei; Zhang, Xiaoxiao; Xu, Mingzi; Chen, Jie; Zhou, Lei

    2018-05-01

    Wood-plastic composites were prepared from polyethylene terephthalate- 1,4-cyclohexanedimethanol ester (PETG) and waste-paper fiber that was unmodified, modified with alkyl-ketene-dimer (AKD), and modified with a silane-coupling agent. The mechanical properties, water absorption properties, surface structure, and thermal properties of the three prepared materials were compared. The results showed that the optimum amount of waste-paper powder is 10 wt%, while that of the waste-paper particles is 60-80 mesh. The use of AKD and coupling agent KH550 can reduce the water absorption of the composite; however, the reductive effect of the coupling agent is better, in that it is reduced by 0.3%. Modification using a 1-wt% KH550 coupling agent can effectively increase the tensile strength of a composite from 31.36 to 41.67 MPa (increase of 32.8%), while the bending strength increased from 86.47 to 98.31 MPa (increase of 13.7%). This also enhances the thermal stability of the composites. With the addition of the coupling agent, the composite material maintains good mechanical properties even after being immersed in water; this can enable the safe use of these composite materials in outdoor environments.

  5. A FRAMEWORK FOR PERFORMANCE EVALUATION AND MONITORING OF PUBLIC HEALTH PROGRAM USING COMPOSITE PERFORMANCE INDEX

    Directory of Open Access Journals (Sweden)

    Susanta Kumar Gauri

    2017-12-01

    Full Text Available A public health program (PHP taken up by the government of a country refers to all organized measures to prevent disease and promote health among the population, by providing different planned cares/services to the people. Usually, the target population for different PHP are different. The basic requirement for success of a PHP is to ensure that all the planned cares/services are reached to each member of the target population. Therefore, the important performance measures for a PHP are the implementation status of all the planned cares/services under the PHP. However, management and monitoring of a PHP become quite difficult by interpreting separately the information contained in a large number of performance measures. Therefore, usually a metric, called composite performance index (CPI, is evaluated to understand the overall performance of a PHP. However, due a scaling operation involved in the CPI computation procedure, the CPI value does not reveal the true overall implementation status of a PHP and consequently, it is effective for management of a PHP. This paper presents a new approach for CPI computation, in which scaling/normalization of the performance variables is not required and therefore, it can be used for monitoring the true overall implementation status of a PHP in a region. A systematic approach for monitoring a PHP using the CPI values is proposed and applied for monitoring the maternal and child healthcare (MCH program. The results are found effective towards continuous improvement of implementation status.

  6. Characterization and optimization of an ultrasonic piezo-optical ring sensor

    International Nuclear Information System (INIS)

    Frankforter, Erik; Lin, Bin; Giurgiutiu, Victor

    2016-01-01

    A resonant piezo-optical ring sensor with both piezoelectric and fiber Bragg grating (FBG) sensing elements was assessed for ultrasonic wave detection. The ring sensor is an existing device that has been shown experimentally to exhibit a number of sensing features: omnidirectionality, mode selectivity, and frequency tunability. The present study uses finite element modeling to understand these features as a means to characterize and optimize the sensor. A combined vibration-wave propagation modeling approach was used, where the vibrational modeling provided a basis for understanding sensing features, and the wave propagation modeling provided predictive power for sensor performance. The sensor features corresponded to the fundamental vibrational mode of the sensor, particularly to the base motion of this mode. The vibrational modeling was also used to guide sensor optimization, with an emphasis on the FBG and piezoelectric sensing elements. It was found that sensor symmetry and nodes of extraneous resonance modes could be exploited to provide a single-resonance response. A series of pitch-catch guided wave experiments were performed on a thin aluminum plate to assess the optimized sensor configuration. Tuning curves showed a single-frequency response to a Lamb wave and mechanical filtering away from the dominant frequency; the sensor capability for mechanical amplification of a Lamb wave and mechanical amplification of a pencil-lead-break acoustic emission event were also demonstrated. (paper)

  7. Development of a fast piezo-based frequency tuner for superconducting CH cavities

    International Nuclear Information System (INIS)

    Amberg, Michael

    2015-01-01

    In this thesis, a fast piezo-based frequency tuner for current and prospective superconducting (sc) CH-cavities has been developed. The novel tuning concept differs fundamentally from conventional tuning systems for superconducting cavities. So called dynamic bellow tuners are welded into the resonator to act against slow and fast frequency variations during operation. Because of their adjustable length it is possible to specifically influence the capacitance and therefore the resonance frequency of the cavity. To change the length of the dynamic bellow tuners the frequency tuner drive, which consists of a slow tuning device controlled by a stepper motor and a fast piezo-based tuning system, is mounted to the helium vessel of the cavity. To validate the whole tuning concept a frequency tuner drive prototype was built in the workshop of the Institute for Applied Physics (IAP) of Frankfurt University. First successful room temperature measurements show that the developed frequency tuning system is an excellent and promising candidate to fulfill the requirements of slow and fast frequency tuning of sc CH-cavities during operation. Furthermore, several coupled structural and electromagnetic simulations of the sc 325 MHz CH-cavity as well as the sc 217 MHz CH-cavity have been performed with the simulation softwares ANSYS Workbench and CST MicroWave Studio, respectively. With these simulations it was possible to reduce the required frequency range and thus the mechanical stroke of the dynamic bellow tuners on the one hand, and on the other hand the mechanical stability of the particular CH-cavity was investigated to avoid plastic deformations due to limiting external effects. To verify the accuracy of the coupled simulations the structural mechanical behaviour and the resulting frequency variations of the sc CH-cavities dependent on the external influences were measured at room temperature as well as at cryogenic temperatures around 4.2 K. The measurement results of both

  8. High precision silicon piezo resistive SMART pressure sensor

    International Nuclear Information System (INIS)

    Brown, Rod

    2005-01-01

    Instruments for test and calibration require a pressure sensor that is precise and stable. Market forces also dictate a move away from single measurand test equipment and, certainly in the case of pressure, away from single range equipment. A pressure 'module' is required which excels in pressure measurement but is interchangble with sensors for other measurands. A communications interface for such a sensor has been specified. Instrument Digital Output Sensor (IDOS) that permits this interchanagability and allows the sensor to be inside or outside the measuring instrument. This paper covers the design and specification of a silicon diaphragm piezo resistive SMART sensor using this interface. A brief history of instrument sensors will be given to establish the background to this development. Design choices of the silicon doping, bridge energisation method, temperature sensing, signal conversion, data processing, compensation method, communications interface will be discussed. The physical format of the 'in-instrument' version will be shown and then extended to the packaging design for the external version. Test results will show the accuracy achieved exceeds the target of 0.01%FS over a range of temperatures

  9. High precision silicon piezo resistive SMART pressure sensor

    Science.gov (United States)

    Brown, Rod

    2005-01-01

    Instruments for test and calibration require a pressure sensor that is precise and stable. Market forces also dictate a move away from single measurand test equipment and, certainly in the case of pressure, away from single range equipment. A pressure `module' is required which excels in pressure measurement but is interchangble with sensors for other measurands. A communications interface for such a sensor has been specified. Instrument Digital Output Sensor (IDOS) that permits this interchanagability and allows the sensor to be inside or outside the measuring instrument. This paper covers the design and specification of a silicon diaphragm piezo resistive SMART sensor using this interface. A brief history of instrument sensors will be given to establish the background to this development. Design choices of the silicon doping, bridge energisation method, temperature sensing, signal conversion, data processing, compensation method, communications interface will be discussed. The physical format of the `in-instrument' version will be shown and then extended to the packaging design for the external version. Test results will show the accuracy achieved exceeds the target of 0.01%FS over a range of temperatures.

  10. Actuation control of a PiezoMEMS biomimetic robotic jellyfish

    Science.gov (United States)

    Alejandre, Alvaro; Olszewski, Oskar; Jackson, Nathan

    2017-06-01

    Biomimetic micro-robots try to mimic the motion of a living system in the form of a synthetically developed microfabricated device. Dynamic motion of living systems have evolved through the years, but trying to mimic these motions is challenging. Micro-robotics are particular challenging as the fabrication of devices and controlling the motion in 3 dimensions is difficult. However, micro-scale robotics have potential to be used in a wide range of applications. MEMS based robots that can move and function in a liquid environment is of particular interest. This paper describes the development of a piezoMEMS based device that mimics the movement of a jellyfish. The paper focuses on the development of a finite element model that investigates a method of controlling the individual piezoelectric beams in order to create a jet propulsion motion, consisting of a quick excitation pulse followed by a slow recovery pulse in order to maximize thrust and velocity. By controlling the individual beams or legs of the jellyfish robot the authors can control the robot to move precisely in 3 dimensions.

  11. “Climb!” – A Composition Case Study. Actualising and Replicating Virtual Spaces in Classical Music Composition and Performance

    DEFF Research Database (Denmark)

    Kallionpaa, Maria; Gasselseder, Hans-Peter

    2018-01-01

    , for example, the acoustics of the concert hall, the instrumentation, the qualities of the concert instrument, or the technologies used. Today´s electroacoustic repertoires frequently contain manipulation of (either physical or virtual) space or acoustic qualities, which sets new requirements...... to the capabilities of the performers. This leads to a question what these requirements may be and how can the performers and composers best deal with them? Can the space itself form part of the structure of a composition and/or performance? This chapter explores the topic through a composition case study “Climb...

  12. Impact performance of the fibre-cement composites

    International Nuclear Information System (INIS)

    Agopyan, V.; Savastano Junior, H.

    1995-01-01

    The transition zone of short filament fibres randomly dispersed in a paste of ordinary portland cement is analysed. Composites of vegetable fibres (malva, sisal and coir) are compared with those containing chrysotile asbestos and polypropylene fibres. The series of composites are prepared to be tested at the ages of 7, 28, 90 and 180 days. The water-cement ratio is 0.38 and at the age of 28 days specimens with ratio of 0.30 and 0.46 are also tested. The backscattered electron image and energy dispersive spectroscopy identify the major properties of the fibre-matrix interface. The microstructural characteristics are directly associated with the toughness of the composites, once the energy dissipation at transition zone is confirmed. (author). 8 refs., 4 figs., 1 tab

  13. Sensitivity enhancement of polysilicon piezo-resistive pressure sensors with phosphorous diffused resistors

    International Nuclear Information System (INIS)

    Sivakumar, K; Dasgupta, N; Bhat, K N; Natarajan, K

    2006-01-01

    It is generally accepted that the piezo-resistive coefficient in single crystal silicon is higher when P-type impurities such as boron are used for doping the resistors. In this paper we demonstrate that the sensitivity of polycrystalline silicon piezo-resistive pressure sensors can be enhanced considerably when phosphorus diffusion source is used instead of boron dopant for realizing the piezo-resistors. Pressure sensors have been designed and fabricated with the polycrystalline piezo-resistors connected in the form of a Wheatstone bridge and laid out on thermal oxide grown on membranes obtained with a Silicon On Insulator (SOI) approach. The SOI wafers required for this purpose have been realized in-house by Silicon Fusion Bonding (SFB) and etch back technique in our laboratory. This approach provides excellent isolation between the resistors and enables zero temperature coefficient of the polysilicon resistor. The results obtained in our laboratory have clearly demonstrated that by optimizing the phosphorus diffusion temperature and duration, it is possible to achieve sensitivities in excess of 20mV /Bar for bridge input voltage of 10V, with linearity within 1% over a differential pressure range up to 10Bar (10 6 Pascal), and burst pressure in excess of 50 Bar as compared to the 10mV /Bar sensitivity obtained with boron doped polysilicon piezo-resistors. This enhancement is attributed to grain boundary passivation by phosphorous atoms

  14. Confinement Sensing and Signal Optimization via Piezo1/PKA and Myosin II Pathways

    Directory of Open Access Journals (Sweden)

    Wei-Chien Hung

    2016-05-01

    Full Text Available Summary: Cells adopt distinct signaling pathways to optimize cell locomotion in different physical microenvironments. However, the underlying mechanism that enables cells to sense and respond to physical confinement is unknown. Using microfabricated devices and substrate-printing methods along with FRET-based biosensors, we report that, as cells transition from unconfined to confined spaces, intracellular Ca2+ level is increased, leading to phosphodiesterase 1 (PDE1-dependent suppression of PKA activity. This Ca2+ elevation requires Piezo1, a stretch-activated cation channel. Moreover, differential regulation of PKA and cell stiffness in unconfined versus confined cells is abrogated by dual, but not individual, inhibition of Piezo1 and myosin II, indicating that these proteins can independently mediate confinement sensing. Signals activated by Piezo1 and myosin II in response to confinement both feed into a signaling circuit that optimizes cell motility. This study provides a mechanism by which confinement-induced signaling enables cells to sense and adapt to different physical microenvironments. : Hung et al. demonstrate that a Piezo1-dependent intracellular calcium increase negatively regulates protein kinase A (PKA as cells transit from unconfined to confined spaces. The Piezo1/PKA and myosin II signaling modules constitute two confinement-sensing mechanisms. This study provides a paradigm by which signaling enables cells to sense and adapt to different microenvironments.

  15. Measuring leg movements during sleep using accelerometry: comparison with EMG and piezo-electric scored events.

    Science.gov (United States)

    Terrill, Philip I; Leong, Matthew; Barton, Katrina; Freakley, Craig; Downey, Carl; Vanniekerk, Mark; Jorgensen, Greg; Douglas, James

    2013-01-01

    Periodic Limb Movements during Sleep (PLMS) can cause significant disturbance to sleep, resulting in daytime sleepiness and reduced quality of life. In conventional clinical practice, PLMS are measured using overnight electromyogram (EMG) of the tibialis anterior muscle, although historically they have also been measured using piezo-electric gauges placed over the muscle. However, PLMS counts (PLM index) do not correlate well with clinical symptomology. In this study, we propose that because EMG and piezo derived signals measure muscle activation rather than actual movement, they may count events with no appreciable movement of the limb and therefore no contribution to sleep disturbance. The aim of this study is thus to determine the percentage of clinically scored limb movements which are not associated with movement of the great toe measured using accelerometry. 9 participants were studied simultaneously with an overnight diagnostic polysomnogram (including EMG and piezo instrumentation of the right leg) and high temporal resolution accelerometry of the right great toe. Limb movements were scored, and peak acceleration during each scored movement was quantified. Across the participant population, 54.9% (range: 26.7-76.3) and 39.0% (range: 4.8-69.6) of limb movements scored using piezo and EMG instrumentation respectively, were not associated with toe movement measured with accelerometry. If sleep disturbance is the consequence of the limb movements, these results may explain why conventional piezo or EMG derived PLMI is poorly correlated with clinical symptomology.

  16. Tuning Piezo ion channels to detect molecular-scale movements relevant for fine touch

    Science.gov (United States)

    Poole, Kate; Herget, Regina; Lapatsina, Liudmila; Ngo, Ha-Duong; Lewin, Gary R.

    2014-01-01

    In sensory neurons, mechanotransduction is sensitive, fast and requires mechanosensitive ion channels. Here we develop a new method to directly monitor mechanotransduction at defined regions of the cell-substrate interface. We show that molecular-scale (~13 nm) displacements are sufficient to gate mechanosensitive currents in mouse touch receptors. Using neurons from knockout mice, we show that displacement thresholds increase by one order of magnitude in the absence of stomatin-like protein 3 (STOML3). Piezo1 is the founding member of a class of mammalian stretch-activated ion channels, and we show that STOML3, but not other stomatin-domain proteins, brings the activation threshold for Piezo1 and Piezo2 currents down to ~10 nm. Structure–function experiments localize the Piezo modulatory activity of STOML3 to the stomatin domain, and higher-order scaffolds are a prerequisite for function. STOML3 is the first potent modulator of Piezo channels that tunes the sensitivity of mechanically gated channels to detect molecular-scale stimuli relevant for fine touch. PMID:24662763

  17. A Flexure-Guided Piezo Drill for Penetrating the Zona Pellucida of Mammalian Oocytes.

    Science.gov (United States)

    Johnson, Wesley; Dai, Changsheng; Liu, Jun; Wang, Xian; Luu, Devin K; Zhang, Zhuoran; Ru, Changhai; Zhou, Chao; Tan, Min; Pu, Huayan; Xie, Shaorong; Peng, Yan; Luo, Jun; Sun, Yu

    2018-03-01

    Mammalian oocytes such as mouse oocytes have a highly elastic outer membrane, zona pellucida (ZP) that cannot be penetrated without significantly deforming the oocyte, even with a sharp micropipette. Piezo drill devices leverage lateral and axial vibration of the micropipette to accomplish ZP penetration with greatly reduced oocyte deformation. However, existing piezo drills all rely on a large lateral micropipette vibration amplitude ( 20 ) and a small axial vibration amplitude (0.1 ). The very large lateral vibration amplitude has been deemed to be necessary for ZP penetration although it also induces larger oocyte deformation and more oocyte damage. This paper reports on a new piezo drill device that uses a flexure guidance mechanism and a systematically designed pulse train with an appropriate base frequency. Both simulation and experimental results demonstrate that a small lateral vibration amplitude (e.g., 2 ) and an axial vibration amplitude as large as 1.2 were achieved. Besides achieving 100% effectiveness in the penetration of mouse oocytes (n = 45), the new piezo device during ZP penetration induced a small oocyte deformation of 3.4 versus larger than 10 using existing piezo drill devices.

  18. Wettability and Impact Performance of Wood Veneer/Polyester Composites

    Directory of Open Access Journals (Sweden)

    Shayesteh Haghdan

    2015-07-01

    Full Text Available Fiber-reinforced thermosetting composites have been of interest since the 1940s due to their ease of use in processing, fast curing times, and high specific stiffness and strength. While the use of plant fibers in a polyester matrix has been thoroughly studied, only limited information is available regarding using wood as reinforcement. In this study, composites of thin wood veneer and a polyester matrix were made and the difficulties in the lamination and curing processes were investigated. Sheets of Douglas fir, maple, and oak veneers using a catalyzed polyester resin were assembled as unidirectional, balanced, and unbalanced cross-ply laminates. These were compared to control specimens using glass fiber as reinforcement. The impact properties of the samples, with respect to the laminate thicknesses, were characterized using a drop-weight impact tester. The wettability and surface roughness of unsanded and sanded wood veneers were also investigated. Results showed that Douglas fir cross-ply laminates had an impact energy equivalent to glass fiber laminates, making them an interesting alternative to synthetic fiber composites. Wood/polyester laminates absorbed a considerable amount of energy through a higher number of fracture modes. The balanced lay-up limited twisting of the wood/polyester composites. The lowest contact angle and highest wettability were observed in unsanded Douglas fir veneers.

  19. Modelling and analysis of abrasive wear performance of composites ...

    African Journals Online (AJOL)

    It has been observed that fibre length plays a major role in wear phenomenon. The length of the fibre has been optimized using a popular evolutionary technique known as particle swarm optimization (PSO) and neural network. The study recommends that fibre length should be 7-8 mm for minimum wear of the composites.

  20. Performance of mechanical behavior of kenaf fibre reinforced foamed composite

    Science.gov (United States)

    Mahzabin, Mst. Sadia; Hock, Lim Jee; Kang, Lim Siong; Jarghouyeh, Ehsan Nikbakht

    2017-10-01

    This paper investigates the mechanical properties of lightweight foamed composite (LFC) with the inclusion of kenaf fibres and superplasticizer. NaOH treated kenaf fibre contents of 0.4%, 0.45% and 0.5% (by weight of cement) with 5cm length were used in composite. The density of 1000kg/m3 to 2000kg/m3 foamed concrete was used for all the tested specimens. The ratio of cement, sand and water used was 1:1.5:0.45. All the experiments were set up in accordance with International standard methods of testing. In reference to the results and discussion, the different percentages of fibre used were proven to have a lesser contribution towards compressive strength or might even have reduced the result. The results also showed that water absorption and density of the composite mortar increased as the volume of fiber increased from 0.4% to 0.5% However, a higher percentage of fiber inclusions had been recorded to have a positive contribution towards flexural and tensile splitting properties of composites.

  1. Aerospace Composite Materials Delivery Order 0003: Nanocomposite Polymeric Resin Enhancements for Improved Composite Performance

    National Research Council Canada - National Science Library

    Chen, Chenggang

    2002-01-01

    .... The addition of clays does not significantly alter the viscosity or cure kinetics so that the modified resin will still be suitable for liquid composite molding techniques such as resin transfer molding...

  2. Effect of flexure beam geometry and material on the displacement of piezo actuated diaphragm for micropump

    Science.gov (United States)

    Roopa, R.; Navin Karanth, P.; Kulkarni, S. M.

    2018-02-01

    In this paper, we present a COMSOL analysis of flexure diaphragm for piezo actuated valveless micropump. Diaphragms play an important role in micropumps, till now plane diaphragms are commonly used in micropumps. Use of compliant flexure hinges in diaphragm and other MEMS application is one of the new approach to achieving high deflection in diaphragm at low operating voltage. Flexures hinges in diaphragm acts as simply supported beam. Out-off plane compliance value and stiffness is considered for the selection of proper flexure for diaphragm. Diaphragm material also plays an important role in the diaphragm central deflection. Factor considered for diaphragm material selection is resilience; it is the ratio of yield stress to static modulus. Higher is the resilience will leads to higher deflection generated, it also imparts good compliance. Based on the resilience beryllium copper, stainless steel and brass materials are selected for diaphragm analysis. Simulations have been performed using COMSOL multiphysics. This study reports the effect of flexure hinge geometry and diaphragm material on the central deflection of diaphragms and compared with existing plane diaphragm. Simulation results illustrates that the deflection of three flexure diaphragm with 2mm width and 2mm length flexure is 6.75µm for stainless steel, 10.89 for beryllium copper and 12.10µm for brass, at 140V which is approximately twice that of plane diaphragm deflection. The maximum in both plane and three flexure diaphragm deflection is obtained for brass diaphragm compared to stainless steel and beryllium copper.

  3. Processing of fibre composites - challenges for maximum materials performance

    Energy Technology Data Exchange (ETDEWEB)

    Madsen, B.; Lilholt, H.; Kusano, Y.; Faester, S.; Ralph, B. (eds.)

    2013-09-01

    The Proceedings book contains 9 invited papers and 26 contributed papers. Among the specific topics covered by the papers are (1) experiments and theoretical models for the analysis of resin rheology, resin cure kinetics, together with fibre assembly permeability for efficient mould filling, and optimisation of process conditions, (2) modelling of residual stresses generated during processing for control and minimization of shape distortion, (3) design and characterisation of the fibre/matrix interface, and the related technological techniques for surface treatment, (4) development of techniques and analyses for the characterisation of the process controlled volumetric composition and microstructural parameters, such as length and orientation of fibres, and the related effect on composite properties, (5) compaction behaviour of fibre assemblies, (6) new types of fibres and matrices, such as bio-based and at nano-scale, and their processing and properties, and finally, (7) comparative studies and systems for selection, monitoring and control of processes. (LN)

  4. The annealing effects on irradiated SiC piezo resistive pressure sensor

    International Nuclear Information System (INIS)

    Almaz, E.; Blue, T. E.; Zhang, P.

    2009-01-01

    The effects of temperature on annealing of Silicon Carbide (SiC) piezo resistive pressure sensor which was broken after high fluence neutron irradiation, were investigated. Previously, SiC piezo resistive sensor irradiated with gamma ray and fast neutron in the Co-60 gamma-ray irradiator and Beam Port 1 (BP1) and Auxiliary Irradiation Facility (AIF) at the Ohio State University Nuclear Reactor Laboratory (OSUNRL) respectively. The Annealing temperatures were tested up to 400 C. The Pressure-Output voltage results showed recovery after annealing process on SiC piezo resistive pressure sensor. The bridge resistances of the SiC pressure sensor stayed at the same level up to 300 C. After 400 C annealing, the resistance values changed dramatically.

  5. A piezo-film-based measurement system for global haemodynamic assessment

    International Nuclear Information System (INIS)

    Clemente, Fabrizio; Cimmino, Pasquale; Arpaia, Pasquale

    2010-01-01

    A non-invasive piezo-film-based measurement method for haemodynamic assessment is proposed. The design of a system, able to reconstruct the blood pressure waveform online by dealing with problems arising from the piezo-film capacitive nature in the targeted frequency range (from quasi-dc up to 12 Hz), is illustrated. The system is based on a commercial piezo-film placed easily on the radial artery with a special brace without any discomfort for the patient. The analogical conditioning circuit and digital signal processing are continuously tuned with the signal from the sensor to reconstruct the blood pressure signal online. Diagnostic schema, based on physio-pathological models, have been implemented in order to compute online trends of max[dP(t)/d(t)] and volemic status highly useful for the intensivist and anaesthesiologist. The system was characterized by numerical simulation and experimental in vivo comparison to the traditional reference system

  6. Tribo-performance evaluation of ecofriendly brake friction composite materials

    Science.gov (United States)

    Kumar, Naresh; Singh, Tej; Grewal, G. S.

    2018-05-01

    This paper presents the potential of natural fibre in brake friction materials. Natural fibre filled ecofriendly brake friction materials were developed without Kevlar fibre evaluated for tribo-performance on a chase friction testing machine following SAE J 661a standard. Experimental results indicated that natural fibre enhances the fade performance, but depresses the friction and wear performance, whereas Kevlar fibre improves the friction, wear and recovery performance but depresses the fade performance. Also the results revealed that with the increase in natural fibre content, the friction and fade performances enhanced.

  7. Note: A rigid piezo motor with large output force and an effective method to reduce sliding friction force

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Ying; Lu, Qingyou, E-mail: qxl@ustc.edu.cn [High Magnetic Field Laboratory, Chinese Academy of Sciences and University of Science and Technology of China, Hefei, Anhui 230026 (China); Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China); Hou, Yubin [High Magnetic Field Laboratory, Chinese Academy of Sciences and University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2014-05-15

    We present a completely practical TunaDrive piezo motor. It consists of a central piezo stack sandwiched by two arm piezo stacks and two leg piezo stacks, respectively, which is then sandwiched and spring-clamped by a pair of parallel polished sapphire rods. It works by alternatively fast expanding and contracting the arm/leg stacks while slowly expanding/contracting the central stack simultaneously. The key point is that sufficiently fast expanding and contracting a limb stack can make its two sliding friction forces well cancel, resulting in the total sliding friction force is <10% of the total static friction force, which can help increase output force greatly. The piezo motor's high compactness, precision, and output force make it perfect in building a high-quality harsh-condition (vibration resistant) atomic resolution scanning probe microscope.

  8. Note: A rigid piezo motor with large output force and an effective method to reduce sliding friction force.

    Science.gov (United States)

    Guo, Ying; Hou, Yubin; Lu, Qingyou

    2014-05-01

    We present a completely practical TunaDrive piezo motor. It consists of a central piezo stack sandwiched by two arm piezo stacks and two leg piezo stacks, respectively, which is then sandwiched and spring-clamped by a pair of parallel polished sapphire rods. It works by alternatively fast expanding and contracting the arm/leg stacks while slowly expanding/contracting the central stack simultaneously. The key point is that sufficiently fast expanding and contracting a limb stack can make its two sliding friction forces well cancel, resulting in the total sliding friction force is piezo motor's high compactness, precision, and output force make it perfect in building a high-quality harsh-condition (vibration resistant) atomic resolution scanning probe microscope.

  9. Note: A rigid piezo motor with large output force and an effective method to reduce sliding friction force

    International Nuclear Information System (INIS)

    Guo, Ying; Lu, Qingyou; Hou, Yubin

    2014-01-01

    We present a completely practical TunaDrive piezo motor. It consists of a central piezo stack sandwiched by two arm piezo stacks and two leg piezo stacks, respectively, which is then sandwiched and spring-clamped by a pair of parallel polished sapphire rods. It works by alternatively fast expanding and contracting the arm/leg stacks while slowly expanding/contracting the central stack simultaneously. The key point is that sufficiently fast expanding and contracting a limb stack can make its two sliding friction forces well cancel, resulting in the total sliding friction force is <10% of the total static friction force, which can help increase output force greatly. The piezo motor's high compactness, precision, and output force make it perfect in building a high-quality harsh-condition (vibration resistant) atomic resolution scanning probe microscope

  10. Simple method of calculating the transient thermal performance of composite material and its applicable condition

    Institute of Scientific and Technical Information of China (English)

    张寅平; 梁新刚; 江忆; 狄洪发; 宁志军

    2000-01-01

    Degree of mixing of composite material is defined and the condition of using the effective thermal diffusivity for calculating the transient thermal performance of composite material is studied. The analytical result shows that for a prescribed precision of temperature, there is a condition under which the transient temperature distribution in composite material can be calculated by using the effective thermal diffusivity. As illustration, for the composite material whose temperatures of both ends are constant, the condition is presented and the factors affecting the relative error of calculated temperature of composite materials by using effective thermal diffusivity are discussed.

  11. Piezo films with adjustable anisotropic strain for bending actuators with tunable bending profiles

    International Nuclear Information System (INIS)

    Wapler, Matthias C; Stürmer, Moritz; Brunne, Jens; Wallrabe, Ulrike

    2014-01-01

    We present a method to produce in-plane polarized piezo films with a freely adjustable ratio of the strains in orthogonal in-plane directions. They can be used in piezo bending actuators with a tunable curvature profile. The strains are obtained as mean strains from a periodic polarization pattern produced by a suitable doubly interdigitated electrode structure. This mechanism is demonstrated for several examples using PZT sheets. We further discuss how this tuning and the parameters of the electrode layout affect the overall magnitude of the displacement. (paper)

  12. The piezo-magnetic parameters of Terfenol-D: An experimental viewpoint

    International Nuclear Information System (INIS)

    Davino, D.; Giustiniani, A.; Visone, C.

    2012-01-01

    Magnetostrictive and all multifunctional materials have experienced in the last decades a growing technological interest. Several contributions, in the literature, propose the above-mentioned materials in innovative sensors and actuators both for bulk and MEMS devices. More recently, magnetostrictive materials have been proposed for energy harvesting applications by exploiting the so-called Villari effect. In this case, the behavior and the amplitude of the piezo-magnetic coefficients are an important element to evaluate the conversion efficiency. Aim of this paper is to study the experimental behavior of the piezo-magnetic coefficients of a commercial Terfenol-D rod under controlled conditions.

  13. State of the art of durability-performance evaluation of hardened cement based on phase compositions

    International Nuclear Information System (INIS)

    Kurashige, Isao; Imoto, Harutake; Yamamoto, Takeshi; Hironaga, Michihiko

    2006-01-01

    Upgrading durability-performance evaluation technique for concrete is urgently demanded in connection to its application to radio-active waste repository which needs ultra long-term durability. Common concrete structures also require an advanced method for minimizing the life-cycle cost. The purpose of this research is to investigate current problems and future tasks on durability-performance evaluation of hardened cement from the view point of phase composition. Although the phase composition of hardened cement has not fully been reflected to durability-performance evaluation, it influences concrete durability as well as its pore structure. This report reviews state of the art of the factors affecting phase composition, analytical and experimental evaluation techniques for phase composition, and durability-performance evaluation methods of hardened cement based on phase composition. (author)

  14. The effect of z-binding yarns on the electrical properties of 3D woven composites

    KAUST Repository

    Saleh, Mohamed Nasr

    2017-09-28

    Electrical resistance monitoring (ERM) has been used to study the effect of the z-binding yarns on the initial electrical resistance (ER) and its change of three architectures of 3D woven carbon fibre composites namely (orthogonal “ORT”, layer-to-layer “LTL” and angle interlock “AI”) when tested in tension. Specimens are loaded in on-axis “warp” and off-axis “45°” directions. In-situ ERM is achieved using the four-probe technique. Monotonic and cyclic “load/unload” tests are performed to investigate the effect of piezo-resistivity and residual plasticity on resistance variation. The resistance increase for the off-axis loaded specimens (∼90%) is found to be higher than that of their on-axis counterparts (∼20%). In the case of cyclic testing, the resistance increase upon unloading is irreversible which suggests permanent damage presence not piezo-resistive effect. At the moment, it is difficult to obtain a direct correlation between resistance variation and damage in 3D woven composites due to the complexity of the conduction path along the three orthogonal directions, however this study demonstrates the potential of using ERM for damage detection in 3D woven carbon fibre-based composites and highlights the challenges that need to be overcome to establish ERM as a Structural Health Monitoring (SHM) technique for such material systems.

  15. Finite Element Modelling and Analysis of Damage Detection Methodology in Piezo Electric Sensor and Actuator Integrated Sandwich Cantilever Beam

    Science.gov (United States)

    Pradeep, K. R.; Thomas, A. M.; Basker, V. T.

    2018-03-01

    Structural health monitoring (SHM) is an essential component of futuristic civil, mechanical and aerospace structures. It detects the damages in system or give warning about the degradation of structure by evaluating performance parameters. This is achieved by the integration of sensors and actuators into the structure. Study of damage detection process in piezoelectric sensor and actuator integrated sandwich cantilever beam is carried out in this paper. Possible skin-core debond at the root of the cantilever beam is simulated and compared with undamaged case. The beam is actuated using piezoelectric actuators and performance differences are evaluated using Polyvinylidene fluoride (PVDF) sensors. The methodology utilized is the voltage/strain response of the damaged versus undamaged beam against transient actuation. Finite element model of piezo-beam is simulated in ANSYSTM using 8 noded coupled field element, with nodal degrees of freedoms are translations in the x, y directions and voltage. An aluminium sandwich beam with a length of 800mm, thickness of core 22.86mm and thickness of skin 0.3mm is considered. Skin-core debond is simulated in the model as unmerged nodes. Reduction in the fundamental frequency of the damaged beam is found to be negligible. But the voltage response of the PVDF sensor under transient excitation shows significantly visible change indicating the debond. Piezo electric based damage detection system is an effective tool for the damage detection of aerospace and civil structural system having inaccessible/critical locations and enables online monitoring possibilities as the power requirement is minimal.

  16. Hierarchical polypyrrole based composites for high performance asymmetric supercapacitors

    Science.gov (United States)

    Chen, Gao-Feng; Liu, Zhao-Qing; Lin, Jia-Ming; Li, Nan; Su, Yu-Zhi

    2015-06-01

    An advanced asymmetric supercapacitor with high energy density, exploiting hierarchical polypyrrole (PPy) based composites as both the anode [three dimensional (3D) chuzzle-like Ni@PPy@MnO2] and (3D cochleate-like Ni@MnO2@PPy) cathode, has been developed. The ultrathin PPy and flower-like MnO2 orderly coating on the high-conductivity 3D-Ni enhance charge storage while the unique 3D chuzzle-like and 3D cochleate-like structures provide storage chambers and fast ion transport pathways for benefiting the transport of electrolyte ions. The 3D cochleate-like Ni@MnO2@PPy possesses excellent pseudocapacitance with a relatively negative voltage window while preserved EDLC and free transmission channels conducive to hold the high power, providing an ideal cathode for the asymmetric supercapacitor. It is the first report of assembling hierarchical PPy based composites as both the anode and cathode for asymmetric supercapacitor, which exhibits wide operation voltage of 1.3-1.5 V with maximum energy and power densities of 59.8 Wh kg-1 and 7500 W kg-1.

  17. A Composite Model for Employees' Performance Appraisal and Improvement

    Science.gov (United States)

    Manoharan, T. R.; Muralidharan, C.; Deshmukh, S. G.

    2012-01-01

    Purpose: The purpose of this paper is to develop an innovative method of performance appraisal that will be useful for designing a structured training programme. Design/methodology/approach: Employees' performance appraisals are conducted using new approaches, namely data envelopment analysis and an integrated fuzzy model. Interpretive structural…

  18. Polydopamine and MnO2 core-shell composites for high-performance supercapacitors

    Science.gov (United States)

    Hou, Ding; Tao, Haisheng; Zhu, Xuezhen; Li, Maoguo

    2017-10-01

    Polydopamine and MnO2 core-shell composites (PDA@MnO2) for high-performance supercapacitors had been successfully synthesized by a facile and fast method. The morphology, crystalline phase and chemical composition of PDA@MnO2 composites are characterized using SEM, TEM, XRD, EDS and XPS. The performance of PDA@MnO2 composites are further investigated by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy in 1 M Na2SO4 electrolyte. The PDA@MnO2 core-shell nanostructure composites exhibit a high capacitance of 193 F g-1 at the current density of 1A g-1 and retained over 81.2% of its initial capacitance after 2500 cycles of charge-discharge at 2 A g-1. The results manifest that the PDA@MnO2 composites can be potentially applied in supercapacitors.

  19. Sensing and Energy Harvesting Novel Polymer Composites

    NARCIS (Netherlands)

    Zwaag, S. van der; Ende, D.A. van der; Groen, W.A.

    2014-01-01

    This chapter describes the development and properties of novel functional composite materials consisting of aligned piezo-ceramic particles or fibers in a polymeric matrix, which can be fully integrated in thermoset or thermoplastic products. The materials have a low potential for applications

  20. First-Ply-Failure Performance of Composite Clamped Spherical Shells

    Science.gov (United States)

    Ghosh, A.; Chakravorty, D.

    2018-05-01

    The failure aspects of composites are available for plates, but studies of the literature on shells unveils that similar reports on them are very limited in number. The aim of this work was to investigate the first-ply-failure of industrially and aesthetically important spherical shells under uniform loadings. Apart from solving benchmark problems, numerical experiments were carried out with different variations of their parameters to obtain the first-ply-failure stresses by using the finite-element method. The load was increased in steps, and the lamina strains and stresses were put into well-established failure criteria to evaluate their first-ply-failure stress, the failed ply, the point of initiation of failure, and failure modes and tendencies. The results obtained are analyzed to extract the points of engineering significance.

  1. Performance of carbon fiber reinforced rubber composite armour against shaped charge jet penetration

    OpenAIRE

    Yue Lian-yong; Li Wei; Zu Xu-dong; Huang Zheng-xiang; Gao Zhen-yu

    2016-01-01

    Natural rubber is reinforced with carbon fiber; the protective performances of the carbonfiber reinforced rubber composite armour to shaped charge jet have been studied based on the depth of penetration experiments. The craters on the witness blocks, the nature rubber based composite plates’ deformation and the Scanning Electron Microscopy for the hybrid fiber reinforced rubber plate also is analyzed. The results showed that the composite armour can affect the stability of the jet and made pa...

  2. Natural composites: Strength, packing ability and moisture sorption of cellulose fibres, and the related performance of composites

    DEFF Research Database (Denmark)

    Lilholt, Hans; Madsen, Bo

    2012-01-01

    Biobased materials are becoming of increasing interest as potential structural materials for the future. A useful concept in this context is the fibre reinforcement of materials by stiff and strong fibres. The bio-resources can contribute with cellulose fibres and (bio) polymers from hemicelluloses...... in stiffness, on the packing ability of cellulose fibres and the related maximum fibre volume fraction in composites, on the moisture sorption of cellulose fibres and the related mass increase and (large) hygral strains induced, and on the mechanical performance of composites....

  3. Fundamental piezo-Hall coefficients of single crystal p-type 3C-SiC for arbitrary crystallographic orientation

    Science.gov (United States)

    Qamar, Afzaal; Dao, Dzung Viet; Phan, Hoang-Phuong; Dinh, Toan; Dimitrijev, Sima

    2016-08-01

    Piezo-Hall effect in a single crystal p-type 3C-SiC, grown by LPCVD process, has been characterized for various crystallographic orientations. The quantified values of the piezo-Hall effect in heavily doped p-type 3C-SiC(100) and 3C-SiC(111) for different crystallographic orientations were used to obtain the fundamental piezo-Hall coefficients, P 12 = ( 5.3 ± 0.4 ) × 10 - 11 Pa - 1 , P 11 = ( - 2.6 ± 0.6 ) × 10 - 11 Pa - 1 , and P 44 = ( 11.42 ± 0.6 ) × 10 - 11 Pa - 1 . Unlike the piezoresistive effect, the piezo-Hall effect for (100) and (111) planes is found to be independent of the angle of rotation of the device within the crystal plane. The values of fundamental piezo-Hall coefficients obtained in this study can be used to predict the piezo-Hall coefficients in any crystal orientation which is very important for designing of 3C-SiC Hall sensors to minimize the piezo-Hall effect for stable magnetic field sensitivity.

  4. Piezo type mechanosensitive ion channel component 1 functions as a regulator of the cell fate determination of mesenchymal stem cells.

    Science.gov (United States)

    Sugimoto, Asuna; Miyazaki, Aya; Kawarabayashi, Keita; Shono, Masayuki; Akazawa, Yuki; Hasegawa, Tomokazu; Ueda-Yamaguchi, Kimiko; Kitamura, Takamasa; Yoshizaki, Keigo; Fukumoto, Satoshi; Iwamoto, Tsutomu

    2017-12-18

    The extracellular environment regulates the dynamic behaviors of cells. However, the effects of hydrostatic pressure (HP) on cell fate determination of mesenchymal stem cells (MSCs) are not clearly understood. Here, we established a cell culture chamber to control HP. Using this system, we found that the promotion of osteogenic differentiation by HP is depend on bone morphogenetic protein 2 (BMP2) expression regulated by Piezo type mechanosensitive ion channel component 1 (PIEZO1) in MSCs. The PIEZO1 was expressed and induced after HP loading in primary MSCs and MSC lines, UE7T-13 and SDP11. HP and Yoda1, an activator of PIEZO1, promoted BMP2 expression and osteoblast differentiation, whereas inhibits adipocyte differentiation. Conversely, PIEZO1 inhibition reduced osteoblast differentiation and BMP2 expression. Furthermore, Blocking of BMP2 function by noggin inhibits HP induced osteogenic maker genes expression. In addition, in an in vivo model of medaka with HP loading, HP promoted caudal fin ray development whereas inhibition of piezo1 using GsMTx4 suppressed its development. Thus, our results suggested that PIEZO1 is responsible for HP and could functions as a factor for cell fate determination of MSCs by regulating BMP2 expression.

  5. Improving Fatigue Performance of GFRP Composite Using Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Moneeb Genedy

    2015-01-01

    Full Text Available Glass fiber reinforced polymers (GFRP have become a preferable material for reinforcing or strengthening reinforced concrete structures due to their corrosion resistance, high strength to weight ratio, and relatively low cost compared with carbon fiber reinforced polymers (CFRP. However, the limited fatigue life of GFRP hinders their use in infrastructure applications. For instance, the low fatigue life of GFRP caused design codes to impose stringent stress limits on GFRP that rendered their use non-economic under significant cyclic loads in bridges. In this paper, we demonstrate that the fatigue life of GFRP can be significantly improved by an order of magnitude by incorporating Multi-Wall Carbon Nanotubes (MWCNTs during GFRP fabrication. GFRP coupons were fabricated and tested under static tension and cyclic tension with mean fatigue stress equal to 40% of the GFRP tensile strength. Microstructural investigations using scanning electron microscopy (SEM and Fourier Transform Infrared (FTIR spectroscopy were used for further investigation of the effect of MWCNTs on the GFRP composite. The experimental results show the 0.5 wt% and the 1.0 wt% MWCNTs were able to improve the fatigue life of GFRP by 1143% and 986%, respectively, compared with neat GFRP.

  6. Photocatalytic Performance of Carbon Monolith/TiO2 Composite

    Directory of Open Access Journals (Sweden)

    Marina Maletić

    2015-01-01

    Full Text Available The new and simple approach for deposition of catalytically active TiO2 coating on carbon monolith (CM carrier was presented. CM photocatalysts were impregnated with TiO2 using titanium solution and thermal treatment, and their photocatalytic activity was investigated in the process of methylene blue (MB photodegradation. For the purpose of comparison, CM composite photocatalysts were prepared by dip-coating method, which implies binder usage. The presence of TiO2 on CM carrier was confirmed by Raman spectroscopy and scanning electron microscopy. The sorption characteristics of CM and the role of adsorption in the overall process of MB removal were evaluated through amount of surface oxygen groups obtained by temperature-programmed desorption and specific surface area determined by BET method. CM has shown good adsorption properties toward MB due to high amount of surface oxygen groups and relatively high specific surface area. It was concluded that photocatalytic activity increases with CM disc thickness due to increase of MB adsorption and amount of deposited TiO2. Good photocatalytic activity achieved for samples obtained by thermal treatment is the result of better accessibility of MB solution to the TiO2 particles induced by binder absence.

  7. Entrapped air bubbles in piezo-driven inkjet printing: their effect on the droplet velocity

    NARCIS (Netherlands)

    Jong, de J.; Jeurissen, R.J.M.; Borel, H.; Berg, van den M.; Versluis, M.; Wijshoff, H.M.A.; Prosperetti, A.; Reinten, H.; Lohse, D.

    2006-01-01

    Air bubbles entrapped in the ink channel are a major problem in piezo-driven inkjet printing. They grow by rectified diffusion and eventually counteract the pressure buildup at the nozzle, leading to a breakdown of the jetting process. Experimental results on the droplet velocity udrop as a function

  8. Entrapped air bubbles in piezo-driven inkjet printing: Their effect on the droplet velocity

    NARCIS (Netherlands)

    de Jong, J.; Jeurissen, R.J.M.; Borel, Huub; van den Berg, Marc; Wijshoff, Herman; Versluis, Michel; Wijshoff, H.; Reinten, Hans; Prosperetti, Andrea; Lohse, Detlef

    2006-01-01

    Air bubbles entrapped in the ink channel are a major problem in piezo-driven inkjet printing. They grow by rectified diffusion and eventually counteract the pressure buildup at the nozzle, leading to a breakdown of the jetting process. Experimental results on the droplet velocity udrop as a function

  9. Infrared imaging and acoustic sizing of a bubble inside a MEMS piezo ink channel

    NARCIS (Netherlands)

    Bos, van der A.; Segers, T.; Jeurissen, R.J.M.; Berg, van den M.; Reinten, H.; Wijshoff, H.M.A.; Versluis, M.; Lohse, D.

    2011-01-01

    Piezo drop-on-demand inkjet printers are used in an increasing number of applications because of their reliable deposition of droplets onto a substrate. Droplets of a few picoliters are ejected from an inkjet nozzle at frequencies of up to 100 kHz. However, the entrapment of an air microbubble in

  10. The structure of a conserved piezo channel domain reveals a topologically distinct β sandwich fold.

    Science.gov (United States)

    Kamajaya, Aron; Kaiser, Jens T; Lee, Jonas; Reid, Michelle; Rees, Douglas C

    2014-10-07

    Piezo has recently been identified as a family of eukaryotic mechanosensitive channels composed of subunits containing over 2,000 amino acids, without recognizable sequence similarity to other channels. Here, we present the crystal structure of a large, conserved extramembrane domain located just before the last predicted transmembrane helix of C. elegans PIEZO, which adopts a topologically distinct β sandwich fold. The structure was also determined of a point mutation located on a conserved surface at the position equivalent to the human PIEZO1 mutation found in dehydrated hereditary stomatocytosis patients (M2225R). While the point mutation does not change the overall domain structure, it does alter the surface electrostatic potential that may perturb interactions with a yet-to-be-identified ligand or protein. The lack of structural similarity between this domain and any previously characterized fold, including those of eukaryotic and bacterial channels, highlights the distinctive nature of the Piezo family of eukaryotic mechanosensitive channels. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Contribution of current carrier mobility variation to piezo-resistive effect in SmS

    International Nuclear Information System (INIS)

    Vasil'ev, L.N.; Kaminskij, V.V.

    1999-01-01

    The value of the contribution from the change in the current carriers mobility and pressure to the piezo-resistive effect value in the materials on the basis of the samarium, monosulfide is studied. The conclusion, that the value of the piezoresistance of comprehensive compression should not exceed 7x10 -3 MPa -1 at T=300 K, experimental data [ru

  12. Progress in Piezo-Phototronic-Effect-Enhanced Light-Emitting Diodes and Pressure Imaging.

    Science.gov (United States)

    Pan, Caofeng; Chen, Mengxiao; Yu, Ruomeng; Yang, Qing; Hu, Youfan; Zhang, Yan; Wang, Zhong Lin

    2016-02-24

    Wurtzite materials exhibit both semiconductor and piezoelectric properties under strains due to the non-central symmetric crystal structures. The three-way coupling of semiconductor properties, piezoelectric polarization and optical excitation in ZnO, GaN, CdS and other piezoelectric semiconductors leads to the emerging field of piezo-phototronics. This effect can efficiently manipulate the emission intensity of light-emitting diodes (LEDs) by utilizing the piezo-polarization charges created at the junction upon straining to modulate the energy band diagrams and the optoelectronic processes, such as generation, separation, recombination and/or transport of charge carriers. Starting from fundamental physics principles, recent progress in piezo-phototronic-effect-enhanced LEDs is reviewed; following their development from single-nanowire pressure-sensitive devices to high-resolution array matrices for pressure-distribution mapping applications. The piezo-phototronic effect provides a promising method to enhance the light emission of LEDs based on piezoelectric semiconductors through applying static strains, and may find perspective applications in various optoelectronic devices and integrated systems. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Origin of the Force: The Force-From-Lipids Principle Applied to Piezo Channels.

    Science.gov (United States)

    Cox, C D; Bavi, N; Martinac, B

    2017-01-01

    Piezo channels are a ubiquitously expressed, principal type of molecular force sensor in eukaryotes. They enable cells to decode a myriad of physical stimuli and are essential components of numerous mechanosensory processes. Central to their physiological role is the ability to change conformation in response to mechanical force. Here we discuss the evolutionary origin of Piezo in relation to other MS channels in addition to the force that gates Piezo channels. In particular, we discuss whether Piezo channels are inherently mechanosensitive in accordance with the force-from-lipid paradigm which has been firmly established for bacterial MS channels and two-pore domain K + (K 2P ) channels. We also discuss the evidence supporting a reliance on or direct interaction with structural scaffold proteins of the cytoskeleton and extracellular matrix according to the force-from-filament principle. In doing so, we explain the false dichotomy that these distinctions represent. We also discuss the possible unifying models that shed light on channel mechanosensitivity at the molecular level. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Determination of flow-rate characteristics and parameters of piezo pilot valves

    Directory of Open Access Journals (Sweden)

    Takosoglu Jakub

    2017-01-01

    Full Text Available Pneumatic directional valves are used in most industrial pneumatic systems. Most of them are two-stage valves controlled by a pilot valve. Pilot valves are often chosen randomly. Experimental studies in order to determine the flow-rate characteristics and parameters of pilot valves were not conducted. The paper presents experimental research of two piezo pilot valves.

  15. Performance of polymer compositions as carrier to cowpea rhizobial ...

    African Journals Online (AJOL)

    ... was to evaluate inoculant formulations to cowpea (Vigna unguiculata L. Walp) containing polymers as carrier materials and rhizobial strains. To assess the efficiency of the new inoculants formulations, the rhizobial survival in inoculated and stored seeds and the field performance of a selected formulation were evaluated.

  16. Clinical performance of a hybrid resin composite with and without an intermediate layer of flowable resin composite: a 7-year evaluation

    DEFF Research Database (Denmark)

    van Dijken, Jan W V; Pallesen, Ulla

    2011-01-01

    The objective of this prospective clinical follow up was to evaluate the long term clinical performance of a hybrid resin composite in Class II restorations with and without intermediate layer of flowable resin composite....

  17. Simplified High-Performance Roll Out Composite Magnetometer Boom, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — In response to NASA's need for compact, low-cost deployable magnetometer booms for CubeSats, Roccor proposes to develop a Simple High-performance Roll-Out Composite...

  18. Relating performance of thin-film composite forward osmosis membranes to support layer formation and structure

    KAUST Repository

    Tiraferri, Alberto; Yip, Ngai Yin; Phillip, William A.; Schiffman, Jessica D.; Elimelech, Menachem

    2011-01-01

    the technology to the point that it is commercially viable. Here, a systematic investigation of the influence of thin-film composite membrane support layer structure on forward osmosis performance is conducted. The membranes consist of a selective polyamide

  19. High Density Polyethylene Composites Reinforced with Hybrid Inorganic Fillers: Morphology, Mechanical and Thermal Expansion Performance

    Directory of Open Access Journals (Sweden)

    Birm-June Kim

    2013-09-01

    Full Text Available The effect of individual and combined talc and glass fibers (GFs on mechanical and thermal expansion performance of the filled high density polyethylene (HDPE composites was studied. Several published models were adapted to fit the measured tensile modulus and strength of various composite systems. It was shown that the use of silane-modified GFs had a much larger effect in improving mechanical properties and in reducing linear coefficient of thermal expansion (LCTE values of filled composites, compared with the use of un-modified talc particles due to enhanced bonding to the matrix, larger aspect ratio, and fiber alignment for GFs. Mechanical properties and LCTE values of composites with combined talc and GF fillers varied with talc and GF ratio at a given total filler loading level. The use of a larger portion of GFs in the mix can lead to better composite performance, while the use of talc can help lower the composite costs and increase its recyclability. The use of 30 wt % combined filler seems necessary to control LCTE values of filled HDPE in the data value range generally reported for commercial wood plastic composites. Tensile modulus for talc-filled composite can be predicted with rule of mixture, while a PPA-based model can be used to predict the modulus and strength of GF-filled composites.

  20. High Density Polyethylene Composites Reinforced with Hybrid Inorganic Fillers: Morphology, Mechanical and Thermal Expansion Performance.

    Science.gov (United States)

    Huang, Runzhou; Xu, Xinwu; Lee, Sunyoung; Zhang, Yang; Kim, Birm-June; Wu, Qinglin

    2013-09-17

    The effect of individual and combined talc and glass fibers (GFs) on mechanical and thermal expansion performance of the filled high density polyethylene (HDPE) composites was studied. Several published models were adapted to fit the measured tensile modulus and strength of various composite systems. It was shown that the use of silane-modified GFs had a much larger effect in improving mechanical properties and in reducing linear coefficient of thermal expansion (LCTE) values of filled composites, compared with the use of un-modified talc particles due to enhanced bonding to the matrix, larger aspect ratio, and fiber alignment for GFs. Mechanical properties and LCTE values of composites with combined talc and GF fillers varied with talc and GF ratio at a given total filler loading level. The use of a larger portion of GFs in the mix can lead to better composite performance, while the use of talc can help lower the composite costs and increase its recyclability. The use of 30 wt % combined filler seems necessary to control LCTE values of filled HDPE in the data value range generally reported for commercial wood plastic composites. Tensile modulus for talc-filled composite can be predicted with rule of mixture, while a PPA-based model can be used to predict the modulus and strength of GF-filled composites.

  1. Enhanced electrochemical performance of porous activated carbon by forming composite with graphene as high-performance supercapacitor electrode material

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhi-Hang; Yang, Jia-Ying [Central South University, College of Chemistry and Chemical Engineering, Hunan Provincial Key Laboratory of Efficient and Clean Utilization of Manganese Resources (China); Wu, Xiong-Wei [Hunan Agricultural University, College of Science (China); Chen, Xiao-Qing; Yu, Jin-Gang, E-mail: yujg@csu.edu.cn [Central South University, College of Chemistry and Chemical Engineering, Hunan Provincial Key Laboratory of Efficient and Clean Utilization of Manganese Resources (China); Wu, Yu-Ping, E-mail: wuyp@fudan.edu.cn [Fudan University, New Energy and Materials Laboratory (NEML), Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials (China)

    2017-02-15

    In this work, a novel activated carbon containing graphene composite was developed using a fast, simple, and green ultrasonic-assisted method. Graphene is more likely a framework which provides support for activated carbon (AC) particles to form hierarchical microstructure of carbon composite. Scanning electron microscope (SEM), transmission electron microscope (TEM), Brunauer–Emmett–Teller (BET) surface area measurement, thermogravimetric analysis (TGA), Raman spectra analysis, XRD, and XPS were used to analyze the morphology and surface structure of the composite. The electrochemical properties of the supercapacitor electrode based on the as-prepared carbon composite were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), charge/discharge, and cycling performance measurements. It exhibited better electrochemical performance including higher specific capacitance (284 F g{sup −1} at a current density of 0.5 A g{sup −1}), better rate behavior (70.7% retention), and more stable cycling performance (no capacitance fading even after 2000 cycles). It is easier for us to find that the composite produced by our method was superior to pristine AC in terms of electrochemical performance due to the unique conductive network between graphene and AC.

  2. Enhanced electrochemical performance of porous activated carbon by forming composite with graphene as high-performance supercapacitor electrode material

    International Nuclear Information System (INIS)

    Wang, Zhi-Hang; Yang, Jia-Ying; Wu, Xiong-Wei; Chen, Xiao-Qing; Yu, Jin-Gang; Wu, Yu-Ping

    2017-01-01

    In this work, a novel activated carbon containing graphene composite was developed using a fast, simple, and green ultrasonic-assisted method. Graphene is more likely a framework which provides support for activated carbon (AC) particles to form hierarchical microstructure of carbon composite. Scanning electron microscope (SEM), transmission electron microscope (TEM), Brunauer–Emmett–Teller (BET) surface area measurement, thermogravimetric analysis (TGA), Raman spectra analysis, XRD, and XPS were used to analyze the morphology and surface structure of the composite. The electrochemical properties of the supercapacitor electrode based on the as-prepared carbon composite were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), charge/discharge, and cycling performance measurements. It exhibited better electrochemical performance including higher specific capacitance (284 F g"−"1 at a current density of 0.5 A g"−"1), better rate behavior (70.7% retention), and more stable cycling performance (no capacitance fading even after 2000 cycles). It is easier for us to find that the composite produced by our method was superior to pristine AC in terms of electrochemical performance due to the unique conductive network between graphene and AC.

  3. Effect of gamma radiation on the performance of jute fabrics-reinforced polypropylene composites

    Energy Technology Data Exchange (ETDEWEB)

    Haydaruzzaman [Department of Physics, Jahangirnagar University, Savar, Dhaka (Bangladesh); Khan, Ruhul A. [Radiation and Polymer Chemistry Laboratory, Institute of Nuclear Science and Technology, Bangladesh Atomic Energy Commission, G. P.O. Box 3787, Dhaka 1000 (Bangladesh); Khan, Mubarak A. [Radiation and Polymer Chemistry Laboratory, Institute of Nuclear Science and Technology, Bangladesh Atomic Energy Commission, G. P.O. Box 3787, Dhaka 1000 (Bangladesh)], E-mail: makhan.inst@gmail.com; Khan, A.H.; Hossain, M.A. [Department of Physics, Jahangirnagar University, Savar, Dhaka (Bangladesh)

    2009-11-15

    Jute fabrics-reinforced polypropylene (PP) composites (50% fiber) were prepared by compression molding. Composites were fabricated with non-irradiated jute fabrics/non-irradiated PP (C-0), non-irradiated jute fabrics/irradiated PP (C-1), irradiated jute fabrics/non-irradiated PP (C-2) and irradiated jute fabrics/irradiated PP (C-3). It was found that C-3 composite performed the best mechanical properties over other composites. Total radiation dose varied from 250-1000 krad and composites made of using 500 krad showed the best results. The optimized values (C-3 composites) for tensile strength (TS), bending strength (BS) and impact strength (IS) were found to be 63 MPa, 73 MPa and 2.93 kJ/m{sup 2}, respectively.

  4. THE INVESTIGATION TO THE SEX OF BODY COMPOSITION AND PHYSICAL PERFORMANCE OF ELITE MASTER ATHLETES

    OpenAIRE

    Aksel ÇELİK; Mert TUNER

    2010-01-01

    This study was performed to investigate the effect of regular aerobic exercise on body composition by bioelektrik impedance analysis (BIA) methods, respiratory function parameters and physical performance levels. 20 men and 10 women, total 30 long-distance elite master athletes who had joined World, European and The Balkans Championships in Athletics and into at least one degree, were included in the study. The body composition such as skeletal muscle mass, body fat weight, Waist-hip ratio an...

  5. Nonlinear Analysis of Actuation Performance of Shape Memory Alloy Composite Film Based on Silicon Substrate

    Directory of Open Access Journals (Sweden)

    Shuangshuang Sun

    2014-01-01

    Full Text Available The mechanical model of the shape memory alloy (SMA composite film with silicon (Si substrate was established by the method of mechanics of composite materials. The coupled action between the SMA film and Si substrate under thermal loads was analyzed by combining static equilibrium equations, geometric equations, and physical equations. The material nonlinearity of SMA and the geometric nonlinearity of bending deformation were both considered. By simulating and analyzing the actuation performance of the SMA composite film during one cooling-heating thermal cycle, it is found that the final cooling temperature, boundary condition, and the thickness of SMA film have significant effects on the actuation performance of the SMA composite film. Besides, the maximum deflection of the SMA composite film is affected obviously by the geometric nonlinearity of bending deformation when the thickness of SMA film is very large.

  6. Development of high performance electroless Ni-P-HNT composite coatings

    Science.gov (United States)

    Ranganatha, S.; Venkatesha, T. V.; Vathsala, K.

    2012-12-01

    Halloysite nanotubes (HNTs) of the dimension 50 nm × 1-3 μm (diameter × length) are utililized to fabricate the alloy composite by employing electroless/autocatalytic deposition technique. Electroless Ni-P-HNT binary alloy composite coatings are prepared successfully on low carbon steel. These nanotubes were made to get inserted/incorporated into nickel matrix and corresponding composites are examined for their electrochemical, mechanical and tribological performances and compared with that of plain Ni-P. The coatings were characterized using scanning electron microscopy (SEM) and Energy dispersive X-ray analysis (EDX) techniques to analyze surface nature and composition correspondingly. Small amount of incorporated HNTs made Ni-P deposits appreciable enhancement and betterment in corrosion resistance, hardness and friction resistance. This drastic improvement in the properties reflects the effect of addition of HNTs into Ni-P matrix leading to the development of high performance Ni-P-HNT composite coatings.

  7. Modifications Caused by Enzyme-Retting and Their Effect on Composite Performance

    Directory of Open Access Journals (Sweden)

    Jonn A. Foulk

    2011-01-01

    Full Text Available Bethune seed flax was collected from Canada with seed removed using a stripper header and straw pulled and left in field for several weeks. Unretted straw was decorticated providing a coarse fiber bundle feedstock for enzyme treatments. Enzyme treatments using a bacterial pectinolytic enzyme with lyase activity were conducted in lab-scale reactors. Four fiber specimens were created: no retting, minimal retting, moderate retting, and full retting. Fiber characterization tests: strength, elongation, diameter, metal content, wax content, and pH were conducted with significant differences between fibers. Thermosetting vinyl ester resin was used to produce composite panels via vacuum-assisted infusion. Composite performance was evaluated using fiber bundle pull-out, tensile, impact, and interlaminar shear tests. Composite tests indicate that composite panels are largely unchanged among fiber samples. Variation in composite performance might not be realized due to poor interfacial bonding being of larger impact than the more subtle changes incurred by the enzyme treatment.

  8. Polyaniline/single-wall carbon nanotube (PANI/SWCNT) composites for high performance supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Vinay; Miura, Norio [Art, Science and Technology Center for Cooperative Research, Kyushu University, Kasuga-shi, Fukuoka 816-8580 (Japan)

    2006-12-01

    PANI/SWCNT composites were prepared by electrochemical polymerisation of polyaniline onto SWCNTs and their capacitive performance was evaluated by means of cyclic voltammetry and charge-discharge cycling in 1M H{sub 2}SO{sub 4} electrolyte. The PANI/SWCNT composites single electrode showed much higher specific capacitance, specific energy and specific power than pure PANI and SWCNTs. The highest specific capacitance, specific power and specific energy values of 485F/g, 228Wh/kg and 2250W/kg were observed for 73wt.% PANI deposited onto SWCNTs. PANI/SWCNT composites also showed long cyclic stability. Based upon the variations in the surface morphologies and specific capacitance of the composite, a mechanism is proposed to explain enhancement in the capacitive characteristics. The PANI/SWCNT composites have demonstrated the potential as excellent electrode materials for application in high performance supercapacitors. (author)

  9. Study on Fatigue Performance of Composite Bolted Joints with Bolt-Hole Delamination

    Science.gov (United States)

    Liu, M. J.; Yu, S.; Zhao, Q. Y.

    2018-03-01

    Fatigue performance of composite structure with imperfections is a challenging subject at present. Based on cohesive zone method and multi-continuum theory, delamination evolution response and fatigue life prediction of a 3D composite single-lap joint with a bolt-hole have been investigated through computer codes Abaqus and Fe-safe. Results from the comparison of a perfect composite bolted joint with another defect one indicates that a relatively small delamination damage around the bolt hole brings about significant degradation of local material performance. More notably, fatigue life of stress concentration region of composite bolted joints is highly sensitive to external loads, as an increase of 67% cyclic load amplitude leads to an decrease of 99.5% local fatigue life in this study. However, the numerical strategy for solving composite fatigue problems is meaningful to engineering works.

  10. In Touch With the Mechanosensitive Piezo Channels: Structure, Ion Permeation, and Mechanotransduction.

    Science.gov (United States)

    Geng, J; Zhao, Q; Zhang, T; Xiao, B

    2017-01-01

    Mechanotransduction, the conversion of mechanical forces into biological signals, plays critical roles in various physiological and pathophysiological processes in mammals, such as conscious sensing of touch, pain, and sound, as well as unconscious sensing of blood flow-associated shear stress, urine flow, and bladder distention. Among the various molecules involved in mechanotransduction, mechanosensitive (MS) cation channels have long been postulated to represent one critical class of mechanotransducers that directly and rapidly converts mechanical force into electrochemical signals. Despite the awareness of their functional significance, the molecular identities of MS cation channels in mammals had remained elusive for decades till the groundbreaking finding that the Piezo family of genes, including Piezo1 and Piezo2, constitutes their essential components. Since their identification about 6years ago, tremendous progress has been made in understanding their physiological and pathophysiological importance in mechanotransduction and their structure-function relationships of being the prototypic class of mammalian MS cation channels. On the one hand, Piezo proteins have been demonstrated to serve as physiologically and pathophysiologically important mechanotransducers for most, if not all, mechanotransduction processes. On the other hand, they have been shown to form a remarkable three-bladed, propeller-shaped homotrimeric channel complex comprising a separable ion-conducting pore module and mechanotransduction modules. In this chapter, we review the major advancements, with a particular focus on the structural and biophysical features that enable Piezo proteins to serve as sophisticated MS cation channels for force sensing, transduction, and ion conduction. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Performance enhancement of direct ethanol fuel cell using Nafion composites with high volume fraction of titania

    Science.gov (United States)

    Matos, B. R.; Isidoro, R. A.; Santiago, E. I.; Fonseca, F. C.

    2014-12-01

    The present study reports on the performance enhancement of direct ethanol fuel cell (DEFC) at 130 °C with Nafion-titania composite electrolytes prepared by sol-gel technique and containing high volume fractions of the ceramic phase. It is found that for high volume fractions of titania (>10 vol%) the ethanol uptake of composites is largely reduced while the proton conductivity at high-temperatures is weakly dependent on the titania content. Such tradeoff between alcohol uptake and conductivity resulted in a boost of DEFC performance at high temperatures using Nafion-titania composites with high fraction of the inorganic phase.

  12. High performance thermoplastics: A review of neat resin and composite properties

    Science.gov (United States)

    Johnston, Norman J.; Hergenrother, Paul M.

    1987-01-01

    A review was made of the principal thermoplastics used to fabricate high performance composites. Neat resin tensile and fracture toughness properties, glass transition temperatures (Tg), crystalline melt temperatures (Tm) and approximate processing conditions are presented. Mechanical properties of carbon fiber composites made from many of these thermoplastics are given, including flexural, longitudinal tensile, transverse tensile and in-plane shear properties as well as short beam shear and compressive strengths and interlaminar fracture toughness. Attractive features and problems involved in the use of thermo-plastics as matrices for high performance composites are discussed.

  13. Study on Temperature and Synthetic Compensation of Piezo-Resistive Differential Pressure Sensors by Coupled Simulated Annealing and Simplex Optimized Kernel Extreme Learning Machine.

    Science.gov (United States)

    Li, Ji; Hu, Guoqing; Zhou, Yonghong; Zou, Chong; Peng, Wei; Alam Sm, Jahangir

    2017-04-19

    As a high performance-cost ratio solution for differential pressure measurement, piezo-resistive differential pressure sensors are widely used in engineering processes. However, their performance is severely affected by the environmental temperature and the static pressure applied to them. In order to modify the non-linear measuring characteristics of the piezo-resistive differential pressure sensor, compensation actions should synthetically consider these two aspects. Advantages such as nonlinear approximation capability, highly desirable generalization ability and computational efficiency make the kernel extreme learning machine (KELM) a practical approach for this critical task. Since the KELM model is intrinsically sensitive to the regularization parameter and the kernel parameter, a searching scheme combining the coupled simulated annealing (CSA) algorithm and the Nelder-Mead simplex algorithm is adopted to find an optimal KLEM parameter set. A calibration experiment at different working pressure levels was conducted within the temperature range to assess the proposed method. In comparison with other compensation models such as the back-propagation neural network (BP), radius basis neural network (RBF), particle swarm optimization optimized support vector machine (PSO-SVM), particle swarm optimization optimized least squares support vector machine (PSO-LSSVM) and extreme learning machine (ELM), the compensation results show that the presented compensation algorithm exhibits a more satisfactory performance with respect to temperature compensation and synthetic compensation problems.

  14. Piezo-phototronic Effect Enhanced UV/Visible Photodetector Based on Fully Wide Band Gap Type-II ZnO/ZnS Core/Shell Nanowire Array.

    Science.gov (United States)

    Rai, Satish C; Wang, Kai; Ding, Yong; Marmon, Jason K; Bhatt, Manish; Zhang, Yong; Zhou, Weilie; Wang, Zhong Lin

    2015-06-23

    A high-performance broad band UV/visible photodetector has been successfully fabricated on a fully wide bandgap ZnO/ZnS type-II heterojunction core/shell nanowire array. The device can detect photons with energies significantly smaller (2.2 eV) than the band gap of ZnO (3.2 eV) and ZnS (3.7 eV), which is mainly attributed to spatially indirect type-II transition facilitated by the abrupt interface between the ZnO core and ZnS shell. The performance of the device was further enhanced through the piezo-phototronic effect induced lowering of the barrier height to allow charge carrier transport across the ZnO/ZnS interface, resulting in three orders of relative responsivity change measured at three different excitation wavelengths (385, 465, and 520 nm). This work demonstrates a prototype UV/visible photodetector based on the truly wide band gap semiconducting 3D core/shell nanowire array with enhanced performance through the piezo-phototronic effect.

  15. Enhancing Photoresponsivity of Self-Aligned MoS2 Field-Effect Transistors by Piezo-Phototronic Effect from GaN Nanowires.

    Science.gov (United States)

    Liu, Xingqiang; Yang, Xiaonian; Gao, Guoyun; Yang, Zhenyu; Liu, Haitao; Li, Qiang; Lou, Zheng; Shen, Guozhen; Liao, Lei; Pan, Caofeng; Lin Wang, Zhong

    2016-08-23

    We report high-performance self-aligned MoS2 field-effect transistors (FETs) with enhanced photoresponsivity by the piezo-phototronic effect. The FETs are fabricated based on monolayer MoS2 with a piezoelectric GaN nanowire (NW) as the local gate, and a self-aligned process is employed to define the source/drain electrodes. The fabrication method allows the preservation of the intrinsic property of MoS2 and suppresses the scattering center density in the MoS2/GaN interface, which results in high electrical and photoelectric performances. MoS2 FETs with channel lengths of ∼200 nm have been fabricated with a small subthreshold slope of 64 mV/dec. The photoresponsivity is 443.3 A·W(-1), with a fast response and recovery time of ∼5 ms under 550 nm light illumination. When strain is introduced into the GaN NW, the photoresponsivity is further enhanced to 734.5 A·W(-1) and maintains consistent response and recovery time, which is comparable with that of the mechanical exfoliation of MoS2 transistors. The approach presented here opens an avenue to high-performance top-gated piezo-enhanced MoS2 photodetectors.

  16. Performance of Plain Woven Jute Fabric-Reinforced Polyester Matrix Composite in Multilayered Ballistic System

    Directory of Open Access Journals (Sweden)

    Sergio Neves Monteiro

    2018-02-01

    Full Text Available The ballistic performance of plain woven jute fabric-reinforced polyester matrix composites was investigated as the second layer in a multilayered armor system (MAS. Volume fractions of jute fabric, up to 30 vol %, were mixed with orthophthalic polyester to fabricate laminate composites. Ballistic tests were conducted using high velocity 7.62 mm ammunition. The depth of penetration caused by the bullet in a block of clay witness, simulating a human body, was used to evaluate the MAS ballistic performance according to the international standard. The fractured materials after tests were analyzed by scanning electron microscopy (SEM. The results indicated that jute fabric composites present a performance similar to that of the much stronger Kevlar™, which is an aramid fabric laminate, as MAS second layer with the same thickness. The mechanism of this similar ballistic behavior as well as the comparative advantages of the jute fabric composites over the Kevlar™ are discussed.

  17. Performance characterization of geopolymer composites for hot sodium exposed sacrificial layer in fast breeder reactors

    Energy Technology Data Exchange (ETDEWEB)

    Haneefa, K. Mohammed, E-mail: mhkolakkadan@gmail.com [Department of Civil Engineering, IIT Madras, Chennai (India); Santhanam, Manu [Department of Civil Engineering, IIT Madras, Chennai (India); Parida, F. C. [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam (India)

    2013-12-15

    Highlights: • Performance evaluation of geopolymers subjected to hot liquid sodium is performed. • Apart from mechanical properties, micro-analytical techniques are used for material characterization. • The geopolymer composite showed comparatively lesser damage than conventional cement composites. • Geopolymer technology can emerge as a new choice for sacrificial layer in SCFBRs. - Abstract: A sacrificial layer of concrete is used in sodium cooled fast breeder reactors (SCFBRs) to mitigate thermo-chemical effect of accidentally spilled sodium at and above 550 °C on structural concrete. Performance of this layer is governed by thermo-chemical stability of the ingredients of sacrificial layer concrete. Concrete with limestone aggregate is generally used as a sacrificial layer. Conventional cement based systems exhibit instability in hot liquid sodium environment. Geo-polymer composites are well known to perform excellently at elevated temperatures compared to conventional cement systems. This paper discusses performance of such composites subjected to exposure of hot liquid sodium in air. The investigation includes comprehensive evaluation of various geo-polymer composites before any exposure, after heating to 550 °C in air, and after immersing in hot liquid sodium initially heated to 550 °C in air. Results from the current study indicate that hot liquid sodium produces less damage to geopolymer composites than to the existing conventional cement based system. Hence, the geopolymer technology has potential application in mitigating the degrading effects of sodium fires and can emerge as a new choice for sodium exposed sacrificial layer in SCFBRs.

  18. Combustion performance of porous silicon-based energetic composites

    Energy Technology Data Exchange (ETDEWEB)

    Mason, Benjamin Aaron [Los Alamos National Laboratory; Son, Steve F [Los Alamos National Laboratory; Asay, Blaine W [Los Alamos National Laboratory; Cho, Kevin Y [PURDUE UNIV

    2009-01-01

    The combustion performance of oxidizer filled porous silicon(PSi) was studied. PSi samples with diameters of 2.54 cm were fabricated by electrochemical etching. The % porosity of the samples ranged from 55 to 82%. The samples were cut into 3-5 mm strips and filled with the oxidizers NaClO{sub 4} x 1H{sub 2}O, Ca(ClO{sub 4}){sub 2} x 4H{sub 2}O, S and perfluoropolyether (PFPE). The filled PSi was then burned by igniting the sample with a hot NiChrome{trademark} wire. The burns were recorded using high speed photography from which bring rates were calculated. That burning rates showed a strong dependency on quality of the oxidizer loading. The % porosity did not appear to have a direct affect on the burning rates for those studied. PSi loaded with NaClO{sub 4} x 1H{sub 2}O produced burning rates that ranged from 216-349 cm/s. PSi loaded with Ca(ClO{sub 4}){sub x}x 4 H{sub 2}O had burning rates of 154-285 cm/s. An S filled PSi sample burned a rate of 16 to 290 cm/s, and perfluoropolyether loaded PSi burned at a rate of 1.4 cm/s.

  19. A study of Acoustics Performance on Natural Fibre Composite

    Science.gov (United States)

    Nizam Yahya, Musli; Sambu, Mathan; Latif, Hanif Abdul; Junaid, Thuwaibah Mohd

    2017-08-01

    Natural fibres are fibre that can be directly obtained from an animal, mineral, or vegetable sources. Recently natural materials are becoming good alternatives for synthetic material as they provide good health to greener environment. The purpose of this study is to investigate and compare the acoustic characteristics of natural fibres; Kenaf fibre, Ijuk fibre, coconut coir and palm Oil frond. During the processing stage, each fibre is reinforced with 60:40 weight ratio of natural rubber (NR) separately. The fibres are then compressed after the natural rubber (NR) treatment into circular samples, of 28 mm and 100 mm diameters respectively. The thickness of each sample is fixed at 50mm. The acoustical performances were evaluated by using an impedance tube instrument. The frequency peak value of Kenaf is obtained in a range of 700 Hz - 800 Hz, while for coconut coir is at 1000 Hz - 1075 Hz frequency range. Palm oil frond gives high frequency at 850 Hz - 1200 Hz. However, Only Ijuk has obtained the highest frequency range of 3200 Hz - 3400 Hz. The results demonstrate that these fibres are a promising light and environment-friendly sound absorption material as they are ready to replace the common synthetic fibre.

  20. Review of high and ultrahigh performance cementitious composites incorporating various combinations of fibers and ultrafines

    Directory of Open Access Journals (Sweden)

    M.I. Khan

    2017-10-01

    Full Text Available The outcomes of the research in modern cementitious composites have paved the way for their wide use in construction industry. The introduction of short, discontinuous and randomly distributed fibers to these composites has altered their inherent brittleness. Extensive research has been carried out on the effects of using of mono-fibers in a cementitious composite. However, limited reports in the approachable references on the use of hybrid fibers are available. The synergetic interaction between hybrid fibers have beneficial impact on cementitious composites. The incorporation of micro- and nano-pozzolanic materials, such as fly ash and silica fume have been used to develop high performance cementitious composites such as reactive powder concrete, DUCTAL and CEMTEC multiscale. Further developments were recently achieved by the development of ultra-high performance cementitious composites. The matter of developing high and ultrahigh cementitious composites using various kinds of fibers and particles has received enormous attention from the scientific community. This paper presents a comprehensive critical literature review on the area of high and ultra-high performance cement-based materials.

  1. Miniaturized Low-Power Piezo Microvalve for NanoSat and CubeSat Propulsion, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — In the Phase I effort, Busek developed a miniature precision piezo-actuated microvalve weighing 32g and occupying 4.5 cm^3. The valve demonstrated continuous flow...

  2. The structure of new germanates, gallates, borates and silicates with laser, piezo, ferroelectric and ion conducting properties

    International Nuclear Information System (INIS)

    Belokonev, E.L.

    1994-01-01

    The results of structure investigation of more than 50 new crystalline germanates, gallates, borogermanates, borates, and silicates with laser, piezo, ferroelectric, and ion-conducting properties are described. The structure - properties relationship is examined. 71 refs.; 24 figs.; 10 tabs

  3. The effect of carbon nanofillers on the performance of electromechanical polyaniline-based composite actuators

    International Nuclear Information System (INIS)

    García-Gallegos, J C; Martín-Gullón, I; Conesa, J A; Vega-Cantú, Y I; Rodríguez-Macías, F J

    2016-01-01

    Different types of crystalline carbon nanomaterials were used to reinforce polyaniline for use in electromechanical bilayer bending actuators. The objective is to analyze how the different graphitic structures of the nanocarbons affect and improve the in situ polymerized polyaniline composites and their subsequent actuator behavior. The nanocarbons investigated were multiwalled carbon nanotubes, nitrogen-doped carbon nanotubes, helical-ribbon carbon nanofibers and graphene oxide, each one presenting different shape and structural characteristics. Films of nanocarbon-PAni composite were tested in a liquid electrolyte cell system. Experimental design was used to select the type of nanocarbon filler and composite loadings, and yielded a good balance of electromechanical properties. Raman spectroscopy suggests good interaction between PAni and the nanocarbon fillers. Electron microscopy showed that graphene oxide dispersed the best, followed by multiwall carbon nanotubes, while nitrogen-doped nanotube composites showed dispersion problems and thus poor performance. Multiwall carbon nanotube composite actuators showed the best performance based on the combination of bending angle, bending velocity and maximum working cycles, while graphene oxide attained similarly good performance due to its best dispersion. This parallel testing of a broad set of nanocarbon fillers on PAni-composite actuators is unprecedented to the best of our knowledge and shows that the type and properties of the carbon nanomaterial are critical to the performance of electromechanical devices with other conditions remaining equal. (paper)

  4. Enhancement of capacitance performance of activated carbon—Polyaniline composites by introducing methyl orange

    International Nuclear Information System (INIS)

    Jia Yujie; Jiang Jianchun; Sun Kang; Dai Tingyang

    2012-01-01

    Activated carbon–methyl orange–polyaniline (AC–MO–PAn) composites have been synthesized for the first time. The structural properties of the composites have been characterized with nitrogen absorption–desorption, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). The electrostatic force between MO molecules and aniline (An) salt is assumed to promote the adsorption of aniline on the surface of AC. On the other hand, the sulfonic groups in MO molecules play a role of dopant and provide active sites for the polymerization of aniline. Although the loading amount and structure of PAn in as-prepared AC–MO–PAn composites and conventional AC–PAn composites are almost the same, the electrochemical measurements indicate that the AC–MO–PAn composites have preferable capacitive performance and are favorable to be used as the electrode materials in supercapacitors.

  5. Performance of carbon fiber reinforced rubber composite armour against shaped charge jet penetration

    Directory of Open Access Journals (Sweden)

    Yue Lian-yong

    2016-01-01

    Full Text Available Natural rubber is reinforced with carbon fiber; the protective performances of the carbonfiber reinforced rubber composite armour to shaped charge jet have been studied based on the depth of penetration experiments. The craters on the witness blocks, the nature rubber based composite plates’ deformation and the Scanning Electron Microscopy for the hybrid fiber reinforced rubber plate also is analyzed. The results showed that the composite armour can affect the stability of the jet and made part of the jet fracture. The carbon fiber reinforced rubber composite armour has good defence ablity especially when the nature rubber plate hybrid 15% volume percentage carbonfiber and the obliquity angle is 68°. The hybrid fiber reinforced rubber composite armour can be used as a new kind of light protective armour.

  6. Piezo-phototronic effect enhanced UV photodetector based on CuI/ZnO double-shell grown on flexible copper microwire.

    Science.gov (United States)

    Liu, Jingyu; Zhang, Yang; Liu, Caihong; Peng, Mingzeng; Yu, Aifang; Kou, Jinzong; Liu, Wei; Zhai, Junyi; Liu, Juan

    2016-12-01

    In this work, we present a facile, low-cost, and effective approach to fabricate the UV photodetector with a CuI/ZnO double-shell nanostructure which was grown on common copper microwire. The enhanced performances of Cu/CuI/ZnO core/double-shell microwire photodetector resulted from the formation of heterojunction. Benefiting from the piezo-phototronic effect, the presentation of piezocharges can lower the barrier height and facilitate the charge transport across heterojunction. The photosensing abilities of the Cu/CuI/ZnO core/double-shell microwire detector are investigated under different UV light densities and strain conditions. We demonstrate the I-V characteristic of the as-prepared core/double-shell device; it is quite sensitive to applied strain, which indicates that the piezo-phototronic effect plays an essential role in facilitating charge carrier transport across the CuI/ZnO heterojunction, then the performance of the device is further boosted under external strain.

  7. Composites

    International Nuclear Information System (INIS)

    Kasen, M.B.

    1983-01-01

    This chapter discusses the roles of composite laminates and aggregates in cryogenic technology. Filamentary-reinforced composites are emphasized because they are the most widely used composite materials. Topics considered include composite systems and terminology, design and fabrication, composite failure, high-pressure reinforced plastic laminates, low-pressure reinforced plastics, reinforced metals, selectively reinforced structures, the effect of cryogenic temperatures, woven-fabric and random-mat composites, uniaxial fiber-reinforced composites, composite joints in cryogenic structures, joining techniques at room temperature, radiation effects, testing laminates at cryogenic temperatures, static and cyclic tensile testing, static and cyclic compression testing, interlaminar shear testing, secondary property tests, and concrete aggregates. It is suggested that cryogenic composite technology would benefit from the development of a fracture mechanics model for predicting the fitness-for-purpose of polymer-matrix composite structures

  8. Exploration of a digital audio processing platform using a compositional system level performance estimation framework

    DEFF Research Database (Denmark)

    Tranberg-Hansen, Anders Sejer; Madsen, Jan

    2009-01-01

    This paper presents the application of a compositional simulation based system-level performance estimation framework on a non-trivial industrial case study. The case study is provided by the Danish company Bang & Olufsen ICEpower a/s and focuses on the exploration of a digital mobile audio...... processing platform. A short overview of the compositional performance estimation framework used is given followed by a presentation of how it is used for performance estimation using an iterative refinement process towards the final implementation. Finally, an evaluation in terms of accuracy and speed...

  9. Board Composition and Firm Performance: Evidence from BIST 100 Companies in Turkey

    Directory of Open Access Journals (Sweden)

    Mete KARAYEL

    2016-09-01

    Full Text Available This study examines how board composition affects firm performance. Female directors, independent directors and foreign directors and board size were taken as the indicators of board composition. The empirical analysis, based on a sample of 100 firms drawn from the BIST 100 Index over a 3-year period, the years between 2012 and 2014. In the study, for financial performance indicators, Return on Assets, and Return on Equity were used and for market performance indicator Market Value to Book Value was used. After the analysis, it is found that, board composition has an impact on firm performance in BIST 100 companies. This study is unique in terms of analyzing the effects of 2012 regulation of mandating at least 1/3 of all board members to be independent directors and suggesting at least one female director to BIST 100 company boards by Capital Boards of Turkey.

  10. Genome Regions Associated with Functional Performance of Soybean Stem Fibers in Polypropylene Thermoplastic Composites.

    Directory of Open Access Journals (Sweden)

    Yarmilla Reinprecht

    Full Text Available Plant fibers can be used to produce composite materials for automobile parts, thus reducing plastic used in their manufacture, overall vehicle weight and fuel consumption when they replace mineral fillers and glass fibers. Soybean stem residues are, potentially, significant sources of inexpensive, renewable and biodegradable natural fibers, but are not curretly used for biocomposite production due to the functional properties of their fibers in composites being unknown. The current study was initiated to investigate the effects of plant genotype on the performance characteristics of soybean stem fibers when incorporated into a polypropylene (PP matrix using a selective phenotyping approach. Fibers from 50 lines of a recombinant inbred line population (169 RILs grown in different environments were incorporated into PP at 20% (wt/wt by extrusion. Test samples were injection molded and characterized for their mechanical properties. The performance of stem fibers in the composites was significantly affected by genotype and environment. Fibers from different genotypes had significantly different chemical compositions, thus composites prepared with these fibers displayed different physical properties. This study demonstrates that thermoplastic composites with soybean stem-derived fibers have mechanical properties that are equivalent or better than wheat straw fiber composites currently being used for manufacturing interior automotive parts. The addition of soybean stem residues improved flexural, tensile and impact properties of the composites. Furthermore, by linkage and in silico mapping we identified genomic regions to which quantitative trait loci (QTL for compositional and functional properties of soybean stem fibers in thermoplastic composites, as well as genes for cell wall synthesis, were co-localized. These results may lead to the development of high value uses for soybean stem residue.

  11. Effects of variations in fuel pellet composition and size on mixed-oxide fuel pin performance

    International Nuclear Information System (INIS)

    Makenas, B.J.; Jensen, B.W.; Baker, R.B.

    1980-10-01

    Experiments have been conducted which assess the effects on fuel pin performance of specific minor variations from nominal in both fuel pellet size and pellet composition. Such pellets are generally referred to in the literature as rogue pellets. The effect of these rogue pellets on fuel pin and reactor performance is shown to be minimal

  12. Impact of dietary fatty acids on muscle composition, liver lipids, milt composition and sperm performance in European eel

    DEFF Research Database (Denmark)

    Butts, Ian; Baeza, R.; Støttrup, Josianne

    2015-01-01

    of dietary regime on muscle composition, and liver lipids prior to induced maturation, and the resulting sperm composition and performance. To accomplish this fish were reared on three "enhanced" diets and one commercial diet, each with different levels of fatty acids, arachidonic acid (ARA......), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Neutral lipids from the muscle and liver incorporated the majority of the fatty acid profile, while phospholipids incorporated only certain fatty acids. Diet had an effect on the majority of sperm fatty acids, on the total volume of extractable milt...... induced medium milt volumes but had the highest sperm motility. EPA also seems important for sperm quality parameters since diets with higher EPA percentages had a higher volume of milt and higher sperm motility. In conclusion, dietary fatty acids had an influence on fatty acids in the tissues of male eel...

  13. Composite Measures of Health Care Provider Performance: A Description of Approaches

    Science.gov (United States)

    Shwartz, Michael; Restuccia, Joseph D; Rosen, Amy K

    2015-01-01

    Context Since the Institute of Medicine’s 2001 report Crossing the Quality Chasm, there has been a rapid proliferation of quality measures used in quality-monitoring, provider-profiling, and pay-for-performance (P4P) programs. Although individual performance measures are useful for identifying specific processes and outcomes for improvement and tracking progress, they do not easily provide an accessible overview of performance. Composite measures aggregate individual performance measures into a summary score. By reducing the amount of data that must be processed, they facilitate (1) benchmarking of an organization’s performance, encouraging quality improvement initiatives to match performance against high-performing organizations, and (2) profiling and P4P programs based on an organization’s overall performance. Methods We describe different approaches to creating composite measures, discuss their advantages and disadvantages, and provide examples of their use. Findings The major issues in creating composite measures are (1) whether to aggregate measures at the patient level through all-or-none approaches or the facility level, using one of the several possible weighting schemes; (2) when combining measures on different scales, how to rescale measures (using z scores, range percentages, ranks, or 5-star categorizations); and (3) whether to use shrinkage estimators, which increase precision by smoothing rates from smaller facilities but also decrease transparency. Conclusions Because provider rankings and rewards under P4P programs may be sensitive to both context and the data, careful analysis is warranted before deciding to implement a particular method. A better understanding of both when and where to use composite measures and the incentives created by composite measures are likely to be important areas of research as the use of composite measures grows. PMID:26626986

  14. Development of high performance electroless Ni-P-HNT composite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Ranganatha, S., E-mail: kamath.ranganath@gmail.com [Department of studies in chemistry, School of chemical sciences, Kuvempu university, Shankaraghatta-577451, Shimoga, Karnataka (India); Venkatesha, T.V., E-mail: drtvvenkatesha@yahoo.co.uk [Department of studies in chemistry, School of chemical sciences, Kuvempu university, Shankaraghatta-577451, Shimoga, Karnataka (India); Vathsala, K., E-mail: vathsala.mahesh@gmail.com [Nanotribology Laboratory, Mechanical engineering department, Indian Institute of Science, Bangalore 560012, Karnataka (India)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer Novel Ni-P composites were prepared by incorporating Halloysite nanotubes. Black-Right-Pointing-Pointer Mild steel specimens surface engineered by nickel using electroless technique. Black-Right-Pointing-Pointer Incorporated halloysite nanotubes made nickel matrix highly corrosion resistant. Black-Right-Pointing-Pointer HNT composite exhibits high hardness and largely reduces friction. - Abstract: Halloysite nanotubes (HNTs) of the dimension 50 nm Multiplication-Sign 1-3 {mu}m (diameter Multiplication-Sign length) are utililized to fabricate the alloy composite by employing electroless/autocatalytic deposition technique. Electroless Ni-P-HNT binary alloy composite coatings are prepared successfully on low carbon steel. These nanotubes were made to get inserted/incorporated into nickel matrix and corresponding composites are examined for their electrochemical, mechanical and tribological performances and compared with that of plain Ni-P. The coatings were characterized using scanning electron microscopy (SEM) and Energy dispersive X-ray analysis (EDX) techniques to analyze surface nature and composition correspondingly. Small amount of incorporated HNTs made Ni-P deposits appreciable enhancement and betterment in corrosion resistance, hardness and friction resistance. This drastic improvement in the properties reflects the effect of addition of HNTs into Ni-P matrix leading to the development of high performance Ni-P-HNT composite coatings.

  15. Development of high performance electroless Ni–P–HNT composite coatings

    International Nuclear Information System (INIS)

    Ranganatha, S.; Venkatesha, T.V.; Vathsala, K.

    2012-01-01

    Highlights: ► Novel Ni–P composites were prepared by incorporating Halloysite nanotubes. ► Mild steel specimens surface engineered by nickel using electroless technique. ► Incorporated halloysite nanotubes made nickel matrix highly corrosion resistant. ► HNT composite exhibits high hardness and largely reduces friction. - Abstract: Halloysite nanotubes (HNTs) of the dimension 50 nm × 1–3 μm (diameter × length) are utililized to fabricate the alloy composite by employing electroless/autocatalytic deposition technique. Electroless Ni–P–HNT binary alloy composite coatings are prepared successfully on low carbon steel. These nanotubes were made to get inserted/incorporated into nickel matrix and corresponding composites are examined for their electrochemical, mechanical and tribological performances and compared with that of plain Ni–P. The coatings were characterized using scanning electron microscopy (SEM) and Energy dispersive X-ray analysis (EDX) techniques to analyze surface nature and composition correspondingly. Small amount of incorporated HNTs made Ni–P deposits appreciable enhancement and betterment in corrosion resistance, hardness and friction resistance. This drastic improvement in the properties reflects the effect of addition of HNTs into Ni–P matrix leading to the development of high performance Ni–P–HNT composite coatings.

  16. High-performance thermoelectric materials based on ternary TiO2/CNT/PANI composites.

    Science.gov (United States)

    Erden, Fuat; Li, Hui; Wang, Xizu; Wang, FuKe; He, Chaobin

    2018-04-04

    In the present work, we report the fabrication of high-performance thermoelectric materials using TiO2/CNT/PANI ternary composites. We showed that a conductivity of ∼2730 S cm-1 can be achieved for the binary CNT (70%)/PANI (30%) composite, which is the highest recorded value for the reported CNT/PANI composites. We further demonstrated that the Seebeck coefficient of CNT/PANI composites could be enhanced by incorporating TiO2 nanoparticles into the binary CNT/PANI composites, which could be attributed to lower carrier density and the energy scattering of low-energy carriers at the interfaces of TiO2/a-CNT and TiO2/PANI. The resulting TiO2/a-CNT/PANI ternary system exhibits a higher Seebeck coefficient and enhanced thermoelectric power. Further optimization of the thermoelectric power was achieved by water treatment and by tuning the processing temperature. A high thermoelectric power factor of 114.5 μW mK-2 was obtained for the ternary composite of 30% TiO2/70% (a-CNT (70%)/PANI (30%)), which is the highest reported value among the reported PANI based ternary composites. The improvement of thermoelectric performance by incorporation of TiO2 suggests a promising approach to enhance power factor of organic thermoelectric materials by judicial tuning of the carrier concentration and electrical conductivity.

  17. Performance enhancement of quantum dot-sensitized solar cells based on polymer nano-composite catalyst

    International Nuclear Information System (INIS)

    Seo, Hyunwoong; Gopi, Chandu V.V.M.; Kim, Hee-Je; Itagaki, Naho; Koga, Kazunori; Shiratani, Masaharu

    2017-01-01

    Highlights: •We studied polymer nano-composite containing TiO 2 nano-particles as a catalyst. •Polymer nano-composite was applied for quantum dot-sensitized solar cells. •Polymer nano-composite catalyst was considerably improved with TiO 2 nano-particles. •Polymer nano-composite showed higher photovoltaic performance than conventional Au. -- Abstract: Polymer nano-composite composed of poly(3,4-ethylenedioxythiophene):poly (styrenesulfonate) and TiO 2 nano-particles was deposited on fluorine-doped tin oxide substrate and applied as an alternative to Au counter electrode of quantum dot-sensitized solar cell (QDSC). It became surface-richer with the increase in nano-particle amount so that catalytic reaction was increased by widened catalytic interface. Electrochemical impedance spectroscopy and cyclic voltammetry clearly demonstrated the enhancement of polymer nano-composite counter electrode. A QDSC based on polymer nano-composite counter electrode showed 0.56 V of V OC , 12.24 mA cm −2 of J SC , 0.57 of FF, and 3.87% of efficiency and this photovoltaic performance was higher than that of QDSC based on Au counter electrode (3.75%).

  18. Evaluation of mechanical properties and durability performance of HDPE-wood composites

    International Nuclear Information System (INIS)

    Tazi, M.; Erchiqui, F.; Kaddami, H.; Bouazara, M.; Poaty, B.

    2015-01-01

    The objective of this work is to evaluate the mechanical properties and durability performance of bio-composite materials made from sawdust and thermoplastic polymer (HDPE). For the preparation of the composites, sawdust in different proportions with Maleic Anhydride grafted Polyethylene (MAPE) as the coupling agent was used. The thermal and mechanical properties were successively characterized. The results indicate that adding wood fillers to a polymer matrix increases the degree of crystallinity and improves the tensile strength and ductility of composites. On the contrary, resistance to water absorption decreases as a function of the wood fillers. Scanning electron microscopy (SEM) was used to analyze morphological structure alteration when exposed to intense weathering. The biodegradability of bio-composites up to 97 days was also investigated; the results indicate that, by increasing the filler content, the amount of weight loss increased as well. In other words, even though the addition of sawdust to thermoplastic polymer improves the mechanical performance of a composite material, it also accelerates the biodegradation rate of the composite. An optimum amount of filler content might compromise the effect of biodegradation and mechanical properties of composite materials

  19. Evaluation of mechanical properties and durability performance of HDPE-wood composites

    Energy Technology Data Exchange (ETDEWEB)

    Tazi, M.; Erchiqui, F. [Engineering department, Université de Quebec en Abitibi-Témiscamingue (Canada); Kaddami, H. [Université Caddi Ayad Marrakech, Laboratoire ’LCO2MC’, B.P. 549, Marrakech 40000, Maroc (Morocco); Bouazara, M. [Mechanical department, Université de Québec à Chicoutimi Canada (Canada); Poaty, B. [Technology Center of industrial residuals, QC Canada (Canada)

    2015-05-22

    The objective of this work is to evaluate the mechanical properties and durability performance of bio-composite materials made from sawdust and thermoplastic polymer (HDPE). For the preparation of the composites, sawdust in different proportions with Maleic Anhydride grafted Polyethylene (MAPE) as the coupling agent was used. The thermal and mechanical properties were successively characterized. The results indicate that adding wood fillers to a polymer matrix increases the degree of crystallinity and improves the tensile strength and ductility of composites. On the contrary, resistance to water absorption decreases as a function of the wood fillers. Scanning electron microscopy (SEM) was used to analyze morphological structure alteration when exposed to intense weathering. The biodegradability of bio-composites up to 97 days was also investigated; the results indicate that, by increasing the filler content, the amount of weight loss increased as well. In other words, even though the addition of sawdust to thermoplastic polymer improves the mechanical performance of a composite material, it also accelerates the biodegradation rate of the composite. An optimum amount of filler content might compromise the effect of biodegradation and mechanical properties of composite materials.

  20. High performance thermoplastics - A review of neat resin and composite properties

    Science.gov (United States)

    Johnston, Norman J.; Hergenrother, Paul M.

    1987-01-01

    A review was made of the principal thermoplastics used to fabricate high performance composites. Neat resin tensile and fracture toughness properties, glass transition temperatures (Tg), crystalline melt temperatures (Tm) and approximate processing conditions are presented. Mechanical properties of carbon fiber composites made from many of these thermoplastics are given, including flexural, longitudinal tensile, transverse tensile and in-plane shear properties as well as short beam shear and compressive strengths and interlaminar fracture toughness.

  1. Performance of aged cement - polymer composite immobilizing borate waste simulates during flooding scenarios

    International Nuclear Information System (INIS)

    Eskander, S.B.; Bayoumi, T.A.; Saleh, H.M.

    2012-01-01

    An advanced composite of cement and water extended polyester based on the recycled Poly(ethylene terephthalate) waste was developed to incorporate the borate waste. Previous studies have reported the characterizations of the waste composite (cement-polymer composite immobilizing borate waste simulates) after 28 days of curing time. The current work studied the performance of waste composite aged for seven years and subjected to flooding scenario during 260 days using three types of water. The state of waste composite was assessed at the end of each definite interval of the water infiltration through visual examination and mechanical measurement. Scanning electron microscopy, infrared spectroscopy, X-ray diffraction and thermal analyses were used to investigate the changes that may occur in the microstructure of the waste composite under aging and flooding effects. The actual experimental results indicated reasonable evidence for the waste composite. Acceptable consistency was confirmed for the waste composite even after aging seven years and exposure to flooding scenario for 260 days.

  2. Ready to rumble: how team personality composition and task conflict interact to improve performance.

    Science.gov (United States)

    Bradley, Bret H; Klotz, Anthony C; Postlethwaite, Bennett E; Brown, Kenneth G

    2013-03-01

    Although prior work has proposed a number of conditions under which task conflict in teams may improve performance, composition variables have been left unexplored. Given the effects of personality traits on team processes and outcomes demonstrated in prior work, investigating whether specific personality compositions influence the effect of task conflict on team performance is critical to researchers' understanding of conflict in teams. Our results indicate that team-level averages of both openness to experience and emotional stability function as moderators of the relationship between task conflict and team performance. Specifically, task conflict had a positive impact on performance in teams with high levels of openness or emotional stability; in contrast, task conflict had a negative impact on performance in teams with low levels of openness or emotional stability. Thus, when task conflict emerges, teams composed of members who are open minded or emotionally stable are best able to leverage conflict to improve performance. Implications for theory and practice are discussed.

  3. Influence of hydrogen environment on the tribological performance of polymer composites

    International Nuclear Information System (INIS)

    Geraldine Theiler; Thomas Gradt

    2006-01-01

    In the past few years several projects dealing with the influence of hydrogen on the tribological properties of friction couples were conducted at the Federal Institute for Materials Research and Testing. This paper reports some investigations carried out with polymer composites. The results of tribological experiments with PTFE and PEEK composites against steel are presented here. Friction and wear were measured for continuous sliding and analyses of the worn surfaces were performed after the experiments. Tests were performed at room temperature in hydrogen as well as in LH 2 . The influence of hydrogen on the material properties was also evaluated by means of heat treatment in hydrogen before the tribological tests. Results indicate a good performance of the selected composites regarding friction and wear resistance. (authors)

  4. Performance modeling of direct contact membrane distillation (DCMD) seawater desalination process using a commercial composite membrane

    KAUST Repository

    Lee, Junggil

    2015-01-10

    This paper presents the development of a rigorous theoretical model to predict the transmembrane flux of a flat sheet hydrophobic composite membrane, comprising both an active layer of polytetrafluoroethylene and a scrim-backing support layer of polypropylene, in the direct contact membrane distillation (DCMD) process. An integrated model includes the mass, momentum, species and energy balances for both retentate and permeate flows, coupled with the mass transfer of water vapor through the composite membrane and the heat transfer across the membrane and through the boundary layers adjacent to the membrane surfaces. Experimental results and model predictions for permeate flux and performance ratio are compared and shown to be in good agreement. The permeate flux through the composite layer can be ignored in the consideration of mass transfer pathways at the composite membrane. The effect of the surface porosity and the thickness of active and support layers on the process performance of composite membrane has also been studied. Among these parameters, surface porosity is identified to be the main factor significantly influencing the permeate flux and performance ratio, while the relative influence of the surface porosity on the performance ratio is less than that on flux.

  5. Thermal buffering performance of composite phase change materials applied in low-temperature protective garments

    Science.gov (United States)

    Yang, Kai; Jiao, Mingli; Yu, Yuanyuan; Zhu, Xueying; Liu, Rangtong; Cao, Jian

    2017-07-01

    Phase change material (PCM) is increasingly being applied in the manufacturing of functional thermo-regulated textiles and garments. This paper investigated the thermal buffering performance of different composite PCMs which are suitable for the application in functional low-temperature protective garments. First, according to the criteria selecting PCM for functional textiles/garments, three kinds of pure PCM were selected as samples, which were n-hexadecane, n-octadecane and n-eicosane. To get the adjustable phase change temperature range and higher phase change enthalpy, three kinds of composite PCM were prepared using the above pure PCM. To evaluate the thermal buffering performance of different composite PCM samples, the simulated low-temperature experiments were performed in the climate chamber, and the skin temperature variation curves in three different low temperature conditions were obtained. Finally composite PCM samples’ thermal buffering time, thermal buffering capacity and thermal buffering efficiency were calculated. Results show that the comprehensive thermal buffering performance of n-octadecane and n-eicosane composite PCM is the best.

  6. Robust independent modal space control of a coupled nano-positioning piezo-stage

    Science.gov (United States)

    Zhu, Wei; Yang, Fufeng; Rui, Xiaoting

    2018-06-01

    In order to accurately control a coupled 3-DOF nano-positioning piezo-stage, this paper designs a hybrid controller. In this controller, a hysteresis observer based on a Bouc-Wen model is established to compensate the hysteresis nonlinearity of the piezoelectric actuator first. Compared to hysteresis compensations using Preisach model and Prandt-Ishlinskii model, the compensation method using the hysteresis observer is computationally lighter. Then, based on the proposed dynamics model, by constructing the modal filter, a robust H∞ independent modal space controller is designed and utilized to decouple the piezo-stage and deal with the unmodeled dynamics, disturbance, and hysteresis compensation error. The effectiveness of the proposed controller is demonstrated experimentally. The experimental results show that the proposed controller can significantly achieve the high-precision positioning.

  7. Analogy between dynamics of thermo-rheological and piezo-rheological pendulums

    International Nuclear Information System (INIS)

    Hedrih, K

    2008-01-01

    The constitutive stress-strain relations of the standard thermo-rheological and piezo-rheological hereditary element in differential form as well as in two different integro-differential forms are defined. The considered problem of a thermo-rheological hereditary discrete system nonlinear dynamics in the form of thermo-rheological double pendulum system with coupled pendulums gets the significance of two constrained bodies in plane motion problem, as a problem important for studying a sensor dynamics or actuator dynamics in active structure dynamics. System of the averaged equations in the first approximation for amplitudes and phases are derived and qualitatively analyzed. Analogy between nonlinear dynamics of the double pendulum systems with thermo-rheological and piezo-rheological properties between pendulums is pointed out

  8. On compressible and piezo-viscous flow in thin porous media.

    Science.gov (United States)

    Pérez-Ràfols, F; Wall, P; Almqvist, A

    2018-01-01

    In this paper, we study flow through thin porous media as in, e.g. seals or fractures. It is often useful to know the permeability of such systems. In the context of incompressible and iso-viscous fluids, the permeability is the constant of proportionality relating the total flow through the media to the pressure drop. In this work, we show that it is also relevant to define a constant permeability when compressible and/or piezo-viscous fluids are considered. More precisely, we show that the corresponding nonlinear equation describing the flow of any compressible and piezo-viscous fluid can be transformed into a single linear equation. Indeed, this linear equation is the same as the one describing the flow of an incompressible and iso-viscous fluid. By this transformation, the total flow can be expressed as the product of the permeability and a nonlinear function of pressure, which represents a generalized pressure drop.

  9. Monolithic optofluidic mode coupler for broadband thermo- and piezo-optical characterization of liquids.

    Science.gov (United States)

    Pumpe, Sebastian; Chemnitz, Mario; Kobelke, Jens; Schmidt, Markus A

    2017-09-18

    We present a monolithic fiber device that enables investigation of the thermo- and piezo-optical properties of liquids using straightforward broadband transmission measurements. The device is a directional mode coupler consisting of a multi-mode liquid core and a single-mode glass core with pronounced coupling resonances whose wavelength strongly depend on the operation temperature. We demonstrated the functionality and flexibility of our device for carbon disulfide, extending the current knowledge of the thermo-optic coefficient by 200 nm at 20 °C and uniquely for high temperatures. Moreover, our device allows measuring the piezo-optic coefficient of carbon disulfide, confirming results first obtained by Röntgen in 1891. Finally, we applied our approach to obtain the dispersion of the thermo-optic coefficients of benzene and tetrachloroethylene between 450 and 800 nm, whereas no data was available for the latter so far.

  10. Digital Imaging and Piezo-dispenser Actuator in Automatic Flocculation Control

    Directory of Open Access Journals (Sweden)

    Jani TOMPERI

    2012-01-01

    Full Text Available This study presents an image-based on-line control system for a coiled pipe flocculator. A digital imaging technique developed previously is utilized to measure the characteristic floc size and a high-pressure piezo-dispenser is introduced for accurate dosing and rapid mixing of the flocculant. The controller is a conventional PI controller. Step change experiments on feed water quality, flow rate and desired floc size have been carried out for controller tuning and testing. The paper shows that the piezo-dispenser provides better flocculation results than a conventional dosing pump, and the flocculation result can be automatically controlled even when the feed water quality rapidly changes. The proposed flocculator is a simple, inexpensive and practical system for long-term laboratory tests to investigate the functionality of flocculants on varying feed waters.

  11. Influence of the Lubricant Thermo-Piezo-Viscous Property on Hydrostatic Bearings in Oil Hydraulics

    DEFF Research Database (Denmark)

    Johansen, Per; Roemer, Daniel Beck; Andersen, Torben O.

    2016-01-01

    adds to the discrepancy of such simple design approach. In this paper the hydrostatic pressure force calculation is reviewed in terms of thermohydrodynamic (THD) lubrication theory, and simple analytical approximations of the hydrostatic pressure force, incorporating the piezo-viscous and thermo...... of these analytical approximations are explored in order to clarify the limits of application. In conclusion, it is found that the spatial gradient of the thermal field on the bearing surface is the significant factor in the thermo-viscous effect on the hydrostatic pressure profile, which leads to the conclusion...... that design engineers need to understand the thermodynamics of hydrostatic bearings, when using the conventional simple analytical approach, neglecting thermo-piezo-viscosity, in hydrostatic pressure force calculations....

  12. Effect of ramadan fasting on body composition and physical performance in female athletes.

    Science.gov (United States)

    Memari, Amir-Hossein; Kordi, Ramin; Panahi, Nekoo; Nikookar, Laya R; Abdollahi, Mohammad; Akbarnejad, Ali

    2011-09-01

    The aim of this study was to determine the effect of Ramadan fasting on body composition, calorie intake and physical performance in young female athletes undertaking training sessions during Ramadan. Twelve voluntary female athletes (15-27 years old) were assigned to the research. A prospective study was conducted to investigate the athletes on four different occasions: one week before Ramadan (T1), the second (T2) and fourth (T3) weeks of Ramadan, and two weeks after the end of Ramadan (T4). Food intake, body composition and physical performance (agility, balance and explosive leg power) were investigated on each occasion. Further, Physical performance was assessed by agility, vertical jump and balance tests. There was a significant main effect for time for body composition indices. A significant decrease was observed in weight (P=0.01) and body mass index (BMI) (P=0.01) in T2 compared with T1, further decrease in weight (Peffect for time for agility performance (P=0.03), but no significant main effect for time was observed for vertical jumping (P=0.1) and balance performance (P=0.3). This study has found that Ramadan fasting could affect the body composition, but not physical performance in female athletes during Ramadan.

  13. A Fast Optimization Method for Reliability and Performance of Cloud Services Composition Application

    Directory of Open Access Journals (Sweden)

    Zhao Wu

    2013-01-01

    Full Text Available At present the cloud computing is one of the newest trends of distributed computation, which is propelling another important revolution of software industry. The cloud services composition is one of the key techniques in software development. The optimization for reliability and performance of cloud services composition application, which is a typical stochastic optimization problem, is confronted with severe challenges due to its randomness and long transaction, as well as the characteristics of the cloud computing resources such as openness and dynamic. The traditional reliability and performance optimization techniques, for example, Markov model and state space analysis and so forth, have some defects such as being too time consuming and easy to cause state space explosion and unsatisfied the assumptions of component execution independence. To overcome these defects, we propose a fast optimization method for reliability and performance of cloud services composition application based on universal generating function and genetic algorithm in this paper. At first, a reliability and performance model for cloud service composition application based on the multiple state system theory is presented. Then the reliability and performance definition based on universal generating function is proposed. Based on this, a fast reliability and performance optimization algorithm is presented. In the end, the illustrative examples are given.

  14. Chemical gas sensors based on functionalized self-actuated piezo-resistive cantilevers

    OpenAIRE

    Filenko, Denys

    2008-01-01

    Der Schwerpunkt dieser Arbeit liegt in der Anwendung funktionalisierter Mikrocantilever mit integrierter bimorpher Aktuation und piezo-resistiver Detektion als chemische Gassensoren für den schnellen, tragbaren und preisgünstigen Nachweis verschiedener flüchtiger Substanzen. Besondere Beachtung erfährt die Verbesserung der Cantilever-Arbeitsleistung durch den Betrieb in speziellen Modi. Weiterer Schwerpunkt liegt in der Untersuchung von spezifischen Sorptionswechselwirkungen und Anwendung von...

  15. Piezo-phototronic Boolean logic and computation using photon and strain dual-gated nanowire transistors.

    Science.gov (United States)

    Yu, Ruomeng; Wu, Wenzhuo; Pan, Caofeng; Wang, Zhaona; Ding, Yong; Wang, Zhong Lin

    2015-02-04

    Using polarization charges created at the metal-cadmium sulfide interface under strain to gate/modulate electrical transport and optoelectronic processes of charge carriers, the piezo-phototronic effect is applied to process mechanical and optical stimuli into electronic controlling signals. The cascade nanowire networks are demonstrated for achieving logic gates, binary computations, and gated D latches to store information carried by these stimuli. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Characterization of a next-generation piezo bimorph X-ray mirror for synchrotron beamlines

    Energy Technology Data Exchange (ETDEWEB)

    Alcock, Simon G., E-mail: simon.alcock@diamond.ac.uk; Nistea, Ioana; Sutter, John P.; Sawhney, Kawal [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE (United Kingdom); Fermé, Jean-Jacques; Thellièr, Christophe; Peverini, Luca [Thales-SESO, 305 rue Louis Armand, Pôle d’Activités d’Aix les Milles, Aix-en-Provence (France)

    2015-01-01

    A next-generation bimorph mirror with piezos bonded to the side faces of a monolithic substrate was created. When replacing a first-generation bimorph mirror suffering from the junction effect, the new type of mirror significantly improved the size and shape of the reflected synchrotron X-ray beam. No evidence of the junction effect was observed even after eight months of continuous beamline usage. Piezo bimorph mirrors are versatile active optics used on many synchrotron beamlines. However, many bimorphs suffer from the ‘junction effect’: a periodic deformation of the optical surface which causes major aberrations to the reflected X-ray beam. This effect is linked to the construction of such mirrors, where piezo ceramics are glued directly below the thin optical substrate. In order to address this problem, a next-generation bimorph with piezos bonded to the side faces of a monolithic substrate was developed at Thales-SESO and optimized at Diamond Light Source. Using metrology feedback from the Diamond-NOM, the optical slope error was reduced to ∼0.5 µrad r.m.s. for a range of ellipses. To maximize usability, a novel holder was built to accommodate the substrate in any orientation. When replacing a first-generation bimorph on a synchrotron beamline, the new mirror significantly improved the size and shape of the reflected X-ray beam. Most importantly, there was no evidence of the junction effect even after eight months of continuous beamline usage. It is hoped that this new design will reinvigorate the use of active bimorph optics at synchrotron and free-electron laser facilities to manipulate and correct X-ray wavefronts.

  17. Characterization of a next-generation piezo bimorph X-ray mirror for synchrotron beamlines

    International Nuclear Information System (INIS)

    Alcock, Simon G.; Nistea, Ioana; Sutter, John P.; Sawhney, Kawal; Fermé, Jean-Jacques; Thellièr, Christophe; Peverini, Luca

    2015-01-01

    A next-generation bimorph mirror with piezos bonded to the side faces of a monolithic substrate was created. When replacing a first-generation bimorph mirror suffering from the junction effect, the new type of mirror significantly improved the size and shape of the reflected synchrotron X-ray beam. No evidence of the junction effect was observed even after eight months of continuous beamline usage. Piezo bimorph mirrors are versatile active optics used on many synchrotron beamlines. However, many bimorphs suffer from the ‘junction effect’: a periodic deformation of the optical surface which causes major aberrations to the reflected X-ray beam. This effect is linked to the construction of such mirrors, where piezo ceramics are glued directly below the thin optical substrate. In order to address this problem, a next-generation bimorph with piezos bonded to the side faces of a monolithic substrate was developed at Thales-SESO and optimized at Diamond Light Source. Using metrology feedback from the Diamond-NOM, the optical slope error was reduced to ∼0.5 µrad r.m.s. for a range of ellipses. To maximize usability, a novel holder was built to accommodate the substrate in any orientation. When replacing a first-generation bimorph on a synchrotron beamline, the new mirror significantly improved the size and shape of the reflected X-ray beam. Most importantly, there was no evidence of the junction effect even after eight months of continuous beamline usage. It is hoped that this new design will reinvigorate the use of active bimorph optics at synchrotron and free-electron laser facilities to manipulate and correct X-ray wavefronts

  18. Identification of a type of defects in CdTe crystals by the piezo spectroscopic method

    International Nuclear Information System (INIS)

    Tarbajev, M.Yi.

    1999-01-01

    The dependence of line shifts and the photoluminescence line intensity of bound exciton complexes on the direction of elastic deformation are studied for CdTe crystals at 4.2 K. On the basis of the found differences in piezo optic behavior of excitons bound to neutral donors and acceptors, the method of identification of a type of defects in CdTe crystals is proposed

  19. Design and Implementation of Output Feedback Control for Piezo Actuated Structure Using Embedded System

    Directory of Open Access Journals (Sweden)

    R.Maheswari

    2008-06-01

    Full Text Available This paper presents the design of periodic output feedback control using state feedback gain to control the vibration of piezo actuated cantilever beam. The effectiveness of the controller is evaluated through simulation and experimentally by exciting the structure at resonance. Real time implementation of the controller is done using microcontroller. The closed loop eigen values of the system with periodic output feedback and state feedback are identical.

  20. Clinical performance of direct versus indirect composite restorations in posterior teeth: A systematic review.

    Science.gov (United States)

    Azeem, Rubeena Abdul; Sureshbabu, Nivedhitha Malli

    2018-01-01

    Composite resin, serves as esthetic alternative to amalgam and cast restorations. Posterior teeth can be restored using direct or indirect composite restorations. The selection between direct and indirect technique is a clinically challenging decision-making process. Most important influencing factor is the amount of remaining tooth substance. The aim of this systematic review was to compare the clinical performance of direct versus indirect composite restorations in posterior teeth. The databases searched included PubMed CENTRAL (until July 2015), Medline, and Cochrane Database of Systematic Reviews. The bibliographies of clinical studies and reviews identified in the electronic search were analyzed to identify studies which were published outside the electronically searched journals. The primary outcome measure was evaluation of the survival of direct and indirect composite restorations in posterior teeth. This review included thirteen studies in which clinical performance of various types of direct and indirect composite restorations in posterior teeth were compared. Out of the thirteen studies which were included seven studies had a high risk of bias and five studies had a moderate risk of bias. One study having a low risk of bias, concluded that there was no significant difference between direct and indirect technique. However, the available evidence revealed inconclusive results. Further research should focus on randomized controlled trials with long term follow-up to give concrete evidence on the clinical performce of direct and indirect composite restorations.

  1. Effect of processing conditions on the interfacial zone of high performances thermoplastic composites

    International Nuclear Information System (INIS)

    Verdeau, Caroline

    1988-01-01

    This study concerns the microstructural and mechanical characterization performances thermoplastic unidirectional composites. Two semi-crystalline composites, APC2 (Peek/Carbon) and AC 40.60 (Pps/carbon) and one amorphous composite FC.PEI (PEI/Carbon) have been studied. Different processing conditions for the APC2 and AC 40.60 specimens have been employed. Amorphous matrix composites (fast cooling rates), crystalline matrix composites (slow cooling rates) and the effects of heat treatments on the matrix (lengthy hold time at the melting point followed by slow cooling) have been studied. Static test (3 points bending tests, transverse tensile tests - ±45 deg., tensile tests) allowed the different interfacial qualities to be revealed. If the fiber/matrix adhesion is excellent for APC2, it is poor for the FCPEI and AC 40.60 composites. The dynamic tests conducted on the torsion pendulum (forced oscillations; low frequencies) have shown for APC2 the existence of trans-crystallinity (mono-dimensional growth, perpendicular to the fiber surface) in the vicinity of the fiber. It has been shown that the fraction of trans-crystallinity is most important for treated specimens. In this study, an approach of the modelization of the viscoelastic behaviour of composites materials has been proposed. (author) [fr

  2. Composition

    DEFF Research Database (Denmark)

    Bergstrøm-Nielsen, Carl

    2011-01-01

    Strategies are open compositions to be realised by improvising musicians. See more about my composition practise in the entry "Composition - General Introduction". Caution: streaming the sound files will in some cases only provide a few minutes' sample. Please DOWNLOAD them to hear them in full...

  3. Composition

    DEFF Research Database (Denmark)

    2014-01-01

    Memory Pieces are open compositions to be realised solo by an improvising musicians. See more about my composition practise in the entry "Composition - General Introduction". Caution: streaming the sound files will in some cases only provide a few minutes' sample. Please DOWNLOAD them to hear them...

  4. The Application of a Piezo-Resistive Cardiorespiratory Sensor System in an Automobile Safety Belt

    Science.gov (United States)

    Hamdani, Syed Talha Ali; Fernando, Anura

    2015-01-01

    Respiratory and heart failure are conditions that can occur with little warning and may also be difficult to predict. Therefore continuous monitoring of these bio-signals is advantageous for ensuring human health. The car safety belt is mainly designed to secure the occupants of the vehicle in the event of an accident. In the current research a prototype safety belt is developed, which is used to acquire respiratory and heart signals, under laboratory conditions. The current safety belt is constructed using a copper ink based nonwoven material, which works based on the piezo-resistive effect due to the pressure exerted on the sensor as a result of expansion of the thorax/abdomen area of the body for respiration and due to the principle of ballistocardiography (BCG) in heart signal sensing. In this research, the development of a theoretical model to qualitatively describe the piezo-resistive material is also presented in order to predict the relative change in the resistance of the piezo-resistive material due to the pressure applied. PMID:25831088

  5. Snoring detection using a piezo snoring sensor based on hidden Markov models.

    Science.gov (United States)

    Lee, Hyo-Ki; Lee, Jeon; Kim, Hojoong; Ha, Jin-Young; Lee, Kyoung-Joung

    2013-05-01

    This study presents a snoring detection method based on hidden Markov models (HMMs) using a piezo snoring sensor. Snoring is a major symptom of obstructive sleep apnea (OSA). In most sleep studies, snoring is detected with a microphone. Since these studies analyze the acoustic properties of snoring, they need to acquire data at high sampling rates, so a large amount of data should be processed. Recently, several sleep studies have monitored snoring using a piezo snoring sensor. However, an automatic method for snoring detection using a piezo snoring sensor has not been reported in the literature. This study proposed the HMM-based method to detect snoring using this sensor, which is attached to the neck. The data from 21 patients with OSA were gathered for training and test sets. The short-time Fourier transform and short-time energy were computed so they could be applied to HMMs. The data were classified as snoring, noise and silence according to their HMMs. As a result, the sensitivity and the positive predictivity values were 93.3% and 99.1% for snoring detection, respectively. The results demonstrated that the method produced simple, portable and user-friendly detection tools that provide an alternative to the microphone-based method.

  6. The application of a piezo-resistive cardiorespiratory sensor system in an automobile safety belt.

    Science.gov (United States)

    Hamdani, Syed Talha Ali; Fernando, Anura

    2015-03-30

    Respiratory and heart failure are conditions that can occur with little warning and may also be difficult to predict. Therefore continuous monitoring of these bio-signals is advantageous for ensuring human health. The car safety belt is mainly designed to secure the occupants of the vehicle in the event of an accident. In the current research a prototype safety belt is developed, which is used to acquire respiratory and heart signals, under laboratory conditions. The current safety belt is constructed using a copper ink based nonwoven material, which works based on the piezo-resistive effect due to the pressure exerted on the sensor as a result of expansion of the thorax/abdomen area of the body for respiration and due to the principle of ballistocardiography (BCG) in heart signal sensing. In this research, the development of a theoretical model to qualitatively describe the piezo-resistive material is also presented in order to predict the relative change in the resistance of the piezo-resistive material due to the pressure applied.

  7. The Application of a Piezo-Resistive Cardiorespiratory Sensor System in an Automobile Safety Belt

    Directory of Open Access Journals (Sweden)

    Syed Talha Ali Hamdani

    2015-03-01

    Full Text Available Respiratory and heart failure are conditions that can occur with little warning and may also be difficult to predict. Therefore continuous monitoring of these bio-signals is advantageous for ensuring human health. The car safety belt is mainly designed to secure the occupants of the vehicle in the event of an accident. In the current research a prototype safety belt is developed, which is used to acquire respiratory and heart signals, under laboratory conditions. The current safety belt is constructed using a copper ink based nonwoven material, which works based on the piezo-resistive effect due to the pressure exerted on the sensor as a result of expansion of the thorax/abdomen area of the body for respiration and due to the principle of ballistocardiography (BCG in heart signal sensing. In this research, the development of a theoretical model to qualitatively describe the piezo-resistive material is also presented in order to predict the relative change in the resistance of the piezo-resistive material due to the pressure applied.

  8. Characterization of a next-generation piezo bimorph X-ray mirror for synchrotron beamlines.

    Science.gov (United States)

    Alcock, Simon G; Nistea, Ioana; Sutter, John P; Sawhney, Kawal; Fermé, Jean Jacques; Thellièr, Christophe; Peverini, Luca

    2015-01-01

    Piezo bimorph mirrors are versatile active optics used on many synchrotron beamlines. However, many bimorphs suffer from the `junction effect': a periodic deformation of the optical surface which causes major aberrations to the reflected X-ray beam. This effect is linked to the construction of such mirrors, where piezo ceramics are glued directly below the thin optical substrate. In order to address this problem, a next-generation bimorph with piezos bonded to the side faces of a monolithic substrate was developed at Thales-SESO and optimized at Diamond Light Source. Using metrology feedback from the Diamond-NOM, the optical slope error was reduced to ∼ 0.5 µrad r.m.s. for a range of ellipses. To maximize usability, a novel holder was built to accommodate the substrate in any orientation. When replacing a first-generation bimorph on a synchrotron beamline, the new mirror significantly improved the size and shape of the reflected X-ray beam. Most importantly, there was no evidence of the junction effect even after eight months of continuous beamline usage. It is hoped that this new design will reinvigorate the use of active bimorph optics at synchrotron and free-electron laser facilities to manipulate and correct X-ray wavefronts.

  9. Snoring detection using a piezo snoring sensor based on hidden Markov models

    International Nuclear Information System (INIS)

    Lee, Hyo-Ki; Lee, Jeon; Lee, Kyoung-Joung; Kim, Hojoong; Ha, Jin-Young

    2013-01-01

    This study presents a snoring detection method based on hidden Markov models (HMMs) using a piezo snoring sensor. Snoring is a major symptom of obstructive sleep apnea (OSA). In most sleep studies, snoring is detected with a microphone. Since these studies analyze the acoustic properties of snoring, they need to acquire data at high sampling rates, so a large amount of data should be processed. Recently, several sleep studies have monitored snoring using a piezo snoring sensor. However, an automatic method for snoring detection using a piezo snoring sensor has not been reported in the literature. This study proposed the HMM-based method to detect snoring using this sensor, which is attached to the neck. The data from 21 patients with OSA were gathered for training and test sets. The short-time Fourier transform and short-time energy were computed so they could be applied to HMMs. The data were classified as snoring, noise and silence according to their HMMs. As a result, the sensitivity and the positive predictivity values were 93.3% and 99.1% for snoring detection, respectively. The results demonstrated that the method produced simple, portable and user-friendly detection tools that provide an alternative to the microphone-based method. (note)

  10. On the use of non-MPB lead zirconium titanate (PZT) granules for piezoelectric ceramic–polymer sensorial composites

    NARCIS (Netherlands)

    Shaji Karapuzha, A.; Kunnamkuzhakkal James, N.; van der Zwaag, S.; Groen, W.A.

    2016-01-01

    Modern flexible and sensitive sensors based on polymer–ceramic composites employ lead zirconate titanate (PZT) granulates having the morphotropic phase boundary (MPB) composition as the piezo active ingredient, as this composition gives the best properties in fully ceramic piezoelectric sensors.

  11. On the use of non-MPB lead zirconium titanate (PZT) granules for piezoelectric ceramic–polymer sensorial composites

    NARCIS (Netherlands)

    Shaji Karapuzha, A.; Zwaag, S. van der; Groen, W.A.

    2016-01-01

    Modern flexible and sensitive sensors based on polymer–ceramic composites employ lead zirconate titanate (PZT) granulates having the morphotropic phase boundary (MPB) composition as the piezo active ingredient, as this composition gives the best properties in fully ceramic piezoelectric sensors. In

  12. Preparation of Reduced Graphene Oxide/MnO Composite and Its Electromagnetic Wave Absorption Performance

    Science.gov (United States)

    Yuan, Jiangtao; Li, Kunzhen; Liu, Zhongfei; Jin, Shaowei; Li, Shikuo; Zhang, Hui

    2018-02-01

    The composite containing reduced graphene oxide and MnO nanoparticles (RGO/MnO) has been prepared via a one step pyrolysis method. The MnO nanoparticles were uniformly dispersed on the surface of RGO nanosheets forming MnO/RGO composite. The composite displays a maximum absorption of ‒38.9 dB at 13.5 GHz and the bandwidth of reflection loss corresponding to -10 dB can reach 4.9 GHz (from 11.5 to 16.4 GHz) with a coating layer thickness of only 2 mm. Therefore, the obtained RGO/MnO composite a perfect lightweight and high-performance electromagnetic wave absorbent.

  13. Photocatalytic Performance of a Novel MOF/BiFeO3 Composite

    Directory of Open Access Journals (Sweden)

    Yunhui Si

    2017-10-01

    Full Text Available In this study, MOF/BiFeO3 composite (MOF, metal-organic framework has been synthesized successfully through a one-pot hydrothermal method. The MOF/BiFeO3 composite samples, pure MOF samples and BiFeO3 samples were characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, energy dispersive spectroscopy (EDS, and by UV–vis spectrophotometry. The results and analysis reveal that MOF/BiFeO3 composite has better photocatalytic behavior for methylene blue (MB compared to pure MOF and pure BiFeO3. The enhancement of photocatalytic performance should be due to the introduction of MOF change the surface morphology of BiFeO3, which will increase the contact area with MB. This composing strategy of MOF/BiFeO3 composite may bring new insight into the designing of highly efficient photocatalysts.

  14. Enhanced electrochemical performances with a copper/xylose-based carbon composite electrode

    Science.gov (United States)

    Sirisomboonchai, Suchada; Kongparakul, Suwadee; Nueangnoraj, Khanin; Zhang, Haibo; Wei, Lu; Reubroycharoen, Prasert; Guan, Guoqing; Samart, Chanatip

    2018-04-01

    Copper/carbon (Cu/C) composites were prepared through the simple and environmentally benign hydrothermal carbonization of xylose in the presence of Cu2+ ions. The morphology, specific surface area, phase structure and chemical composition were investigated. Using a three-electrode system in 0.1 M H2SO4 aqueous electrolyte, the Cu/C composite (10 wt% Cu) heat-treated at 600 °C gave the highest specific capacitance (316.2 and 350.1 F g-1 at 0.5 A g-1 and 20 mV s-1, respectively). The addition of Cu was the major factor in improving the electrochemical performance, enhancing the specific capacitance more than 30 times that of the C without Cu. Therefore, the Cu/C composite presented promising results in improving biomass-based C electrodes for supercapacitors.

  15. Chromium picolinate effects on body composition and muscular performance in wrestlers.

    Science.gov (United States)

    Walker, L S; Bemben, M G; Bemben, D A; Knehans, A W

    1998-12-01

    The purpose of this study was to assess the effects of 14 wk of chromium picolinate supplementation during the final 16 wk of a preseason resistance and conditioning program on body composition and neuromuscular performance in NCAA Division I wrestlers. During this phase of training, wrestlers are primarily interested in trying to improve physical performance and wrestling technique and are not engaged in severe, acute weight loss practices commonly employed before competition. This double-blinded, randomized placebo-controlled study involved 20 wrestlers from the University of Oklahoma assigned to either a treatment group (Cr+3; N = 7; 20.4 yr +/- 0.1) receiving 200 micrograms chromium picolinate daily, a placebo group (P; N = 7; 19.9 yr +/- 0.2), or a control group (C; N = 6; 20.2 yr +/- 0.1) using a stratified random sampling technique based on weight classification. Body composition, neuromuscular performance, metabolic performance, and serum insulin and glucose were measured before and immediately following the supplementation and training period. Repeated measures ANOVA indicated no significant changes in body composition for any of the groups. Aerobic power increased significantly (P pre- to post-test changes in bench press power were significant. These results suggest that chromium picolinate supplementation coupled with a typical preseason training program does not enhance body composition or performance variables beyond improvements seen with training alone.

  16. Tree cover and species composition effects on academic performance of primary school students.

    Science.gov (United States)

    Sivarajah, Sivajanani; Smith, Sandy M; Thomas, Sean C

    2018-01-01

    Human exposure to green space and vegetation is widely recognized to result in physical and mental health benefits; however, to date, the specific effects of tree cover, diversity, and species composition on student academic performance have not been investigated. We compiled standardized performance scores in Grades 3 and 6 for the collective student body in 387 schools across the Toronto District School Board (TDSB), and examined variation in relation to tree cover, tree diversity, and tree species composition based on comprehensive inventories of trees on school properties combined with aerial-photo-based assessments of tree cover. Analyses accounted for variation due to socioeconomic factors using the learning opportunity index (LOI), a regional composite index of external challenges to learning that incorporates income and other factors, such as students with English as a second language. As expected, LOI had the greatest influence on student academic performance; however, the proportion of tree cover, as distinct from other types of "green space" such as grass, was found to be a significant positive predictor of student performance, accounting for 13% of the variance explained in a statistical model predicting mean student performance assessments. The effects of tree cover and species composition were most pronounced in schools that showed the highest level of external challenges, suggesting the importance of urban forestry investments in these schools.

  17. Hemocompatible polyethersulfone/polyurethane composite membrane for high-performance antifouling and antithrombotic dialyzer.

    Science.gov (United States)

    Yin, Zehua; Cheng, Chong; Qin, Hui; Nie, Chuanxiong; He, Chao; Zhao, Changsheng

    2015-01-01

    Researches on blood purification membranes are fuelled by diverse clinical needs, such as hemodialysis, hemodiafiltration, hemofiltration, plasmapheresis, and plasma collection. To approach high-performance dialyzer, the integrated antifouling and antithrombotic properties are highly necessary for the design/modification of advanced artificial membranes. In this study, we propose and demonstrate that the physical blend of triblock polyurethane (PU) and polyethersulfone (PES) may advance the performance of hemodialysis membranes with greatly enhanced blood compatibility. It was found that the triblock PU could be blended with PES at high ratio owing to their excellent miscibility. The surfaces of the PES/PU composite membranes were characterized using attenuated total reflectance-Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, water contact angle measurement, and surface ζ-potentials. The results indicated that the membrane surfaces were assembled with hydrophilic segregation layer owing to the migration of amphiphilic PU segments during membrane preparation, which might confer the composite membranes with superior hemocompatibility. The cross-section scanning electron microscopy images of the composite membranes exhibited structure transformation from finger-like structure to sponge-like structure, which indicated that the composite membrane had tunable porosity and permeability. The further ultrafiltration experiments indicated that the composite membranes showed increased permeability and excellent antifouling ability. The blood compatibility observation indicated that PES/PU composite membranes owned decreased protein adsorption, suppressed platelet adhesion, and prolonged plasma recalcification time. These results indicated that the PES/PU composite membranes exhibited enhanced antifouling and antithrombotic properties than the pristine PES membrane. The strategy may forward the fabrication of blood compatible composite membranes for

  18. Facile synthesis of hybrid CNTs/NiCo2S4 composite for high performance supercapacitors

    Science.gov (United States)

    Li, Delong; Gong, Youning; Pan, Chunxu

    2016-07-01

    In this work, a novel carbon nanotubes (CNTs)/NiCo2S4 composite for high performance supercapacitors was prepared via a simple chemical bath deposition combined with a post-anion exchange reaction. The morphologies and phase structures of the composites were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy (Raman), X-ray photoelectron spectroscopy (XPS) and low-temperature sorption of nitrogen (BET). The electro-chemical tests revealed that the CNT/NiCo2S4 composite exhibited high electrochemical performance, because the CNTs were used as a conductive network for the NiCo2S4 hexagonal nanoplates. Compared with pure NiCo2S4 and the mechanically mixed CNTs/NiCo2S4 composite, the CNTs/NiCo2S4 composite electrode material exhibited excellent supercapacitive performance, such as a high specific capacitance up to 1537 F/g (discharge current density of 1 A/g) and an outstanding rate capability of 78.1% retention as the discharge current density increased to 100 A/g. It is therefore expected to be a promising alternative material in the area of energy storage.

  19. Design and performance prediction of a new generation adsorption chiller using composite adsorbent

    International Nuclear Information System (INIS)

    Gong, L.X.; Wang, R.Z.; Xia, Z.Z.; Chen, C.J.

    2011-01-01

    Research highlights: → Composite adsorbent 'employing lithium chloride in silica gel' and water as working pair. → A new type adsorbent bed is used to accommodate the composite adsorbent. → A dynamic model of the adsorption chiller is built. → The coefficient of performance (COP) and the cooling capacity will be improved. -- Abstract: This paper presents a novel adsorption chiller using composite adsorbent 'employing lithium chloride in silica gel' as adsorbent and water as adsorbate. A new type adsorbent bed is used to accommodate the composite adsorbent. The mass recovery between two adsorbent beds usually results in the adsorbate unbalance. So a novel auto water makeup unite is used to solve the problem. A dynamic model of the adsorption chiller is built based on the adsorption isotherms to predict the performance. The simulation result shows that the coefficient of performance (COP) and the cooling capacity will increase by using this new composite adsorbent. When the temperatures of hot water inlet, cooling water inlet, and chilled water inlet are 363, 303 and 293 K, COP will be 0.43, and the cooling capacity will be 5.295 kW. Also operation strategy is optimized. Different temperatures of hot water inlet, cooling water inlet and chilling water inlet will result in different COP and cooling capacity.

  20. Effect of variation in LPG composition on emissions and performance in a dual fuel diesel engine

    Energy Technology Data Exchange (ETDEWEB)

    H.E. Saleh [Mattaria, Helwan University, Cairo (Egypt). Department of Mechanical Power Engineering

    2008-10-15

    This paper investigates the effect of variation in LPG composition on emissions and performance characteristics in a dual fuel engine run on diesel fuel and five gaseous fuel of LPG with different composition. To quantify the best LPG composition for dual fuel operation especially in order to improve the exhaust emissions quality while maintaining high thermal efficiency comparable to a conventional diesel engine, a two-cylinder, naturally aspirated, four-stroke, DI diesel engine converted to run as pilot-injected dual fuel engine. The tests and data collection were performed under various conditions of load at constant engine speed. From the results, it is observed that the exhaust emissions and fuel conversion efficiency of the dual fuel engine are found to be affected when different LPG composition is used as higher butane content lead to lower NOx levels while higher propane content reduces CO levels. Fuel No. 3 (70% propane, 30% butane) with mass fraction 40% substitution of the diesel fuel was the best LPG composition in the dual fuel operation except that at part loads. Also, tests were made for fuel No. 3-diesel blend in the dual fuel operation at part loads to improve the engine performances and exhaust emissions by using the Exhaust Gas Recirculation (EGR) method. 26 refs., 15 figs., 5 tabs.

  1. Facile synthesis of hybrid CNTs/NiCo2S4 composite for high performance supercapacitors.

    Science.gov (United States)

    Li, Delong; Gong, Youning; Pan, Chunxu

    2016-07-11

    In this work, a novel carbon nanotubes (CNTs)/NiCo2S4 composite for high performance supercapacitors was prepared via a simple chemical bath deposition combined with a post-anion exchange reaction. The morphologies and phase structures of the composites were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy (Raman), X-ray photoelectron spectroscopy (XPS) and low-temperature sorption of nitrogen (BET). The electro-chemical tests revealed that the CNT/NiCo2S4 composite exhibited high electrochemical performance, because the CNTs were used as a conductive network for the NiCo2S4 hexagonal nanoplates. Compared with pure NiCo2S4 and the mechanically mixed CNTs/NiCo2S4 composite, the CNTs/NiCo2S4 composite electrode material exhibited excellent supercapacitive performance, such as a high specific capacitance up to 1537 F/g (discharge current density of 1 A/g) and an outstanding rate capability of 78.1% retention as the discharge current density increased to 100 A/g. It is therefore expected to be a promising alternative material in the area of energy storage.

  2. Surface functionalization of hexagonal boron nitride and its effect on the structure and performance of composites

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Wenqin; Zhang, Wei; Gao, Yuwen [Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, Department of Materials Science and Engineering, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Liang, Guozheng, E-mail: lgzheng@suda.edu.cn [Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, Department of Materials Science and Engineering, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Gu, Aijuan, E-mail: ajgu@suda.edu.cn [Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, Department of Materials Science and Engineering, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Yuan, Li [Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, Department of Materials Science and Engineering, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China)

    2013-04-01

    A new organized hexagonal boron nitride (OhBN) with significantly increased amount of amine groups was synthesized, and characterized by Fourier Transform Infrared (FTIR), X-ray Photoelectron Spectroscopy (XPS), Thermogravimetric (TG) analysis, UV–vis Transmittance Spectra, Transmission Electron Microscope (TEM) and the potentiometric titration. The content of amine groups for OhBN is about 5 times of that for original hexagonal boron nitride (hBN). Based on the preparation of OhBN, new composites consisting of OhBN and bismaleimide (BD) resin were developed, which show greatly improved integrated performance (including dynamic mechanical, dielectric and thermal properties) compared with BD resin and the hBN/BD composites. In the case of the OhBN/BD composite with 15 wt% OhBN, its storage modulus, dielectric loss, thermal conductivity and coefficient of thermal expansion are about 1.2, 0.56, 1.11 and 0.92 times of the corresponding values of hBN/BD composite, respectively; moreover, the glass transition temperature of the former is 15 °C higher than that of the latter. These interesting results suggest that the integrated performance of the composites is closely related to the surface nature of the fillers because the change in the surface nature not only varies the chemical structure, free volume and crosslinking density of the composite, but also determines the interfacial nature between inorganic fillers and the resin matrix. This investigation demonstrates that the method proposed herein provides a new approach to prepare organized inorganic fillers as well as corresponding composites with controlled structure and expected performances for cutting-edge industries.

  3. Rigid-body-spring model numerical analysis of joint performance of engineered cementitious composites and concrete

    Science.gov (United States)

    Khmurovska, Y.; Štemberk, P.; Křístek, V.

    2017-09-01

    This paper presents a numerical investigation of effectiveness of using engineered cementitious composites with polyvinyl alcohol fibers for concrete cover layer repair. A numerical model of a monolithic concaved L-shaped concrete structural detail which is strengthened with an engineered cementitious composite layer with polyvinyl alcohol fibers is created and loaded with bending moment. The numerical analysis employs nonlinear 3-D Rigid-Body-Spring Model. The proposed material model shows reliable results and can be used in further studies. The engineered cementitious composite shows extremely good performance in tension due to the strain-hardening effect. Since durability of the bond can be decreased significantly by its degradation due to the thermal loading, this effect should be also taken into account in the future work, as well as the experimental investigation, which should be performed for validation of the proposed numerical model.

  4. Consequences of sludge composition on combustion performance derived from thermogravimetry analysis

    International Nuclear Information System (INIS)

    Li, Meiyan; Xiao, Benyi; Wang, Xu; Liu, Junxin

    2015-01-01

    Highlights: • Volatiles, particularly proteins, play a key role in sludge combustion. • Sludge combustion performance varies with different sludge organic concentrations. • Carbohydrates significantly affect the combustion rate in the second stage. • Combustion performance of digested sludge is more negative compared with others. - Abstract: Wastewater treatment plants produce millions of tons of sewage sludge. Sewage sludge is recognized as a promising feedstock for power generation via combustion and can be used for energy crisis adaption. We aimed to investigate the quantitative effects of various sludge characteristics on the overall sludge combustion process performance. Different types of sewage sludge were derived from numerous wastewater treatment plants in Beijing for further thermogravimetric analysis. Thermogravimetric–differential thermogravimetric curves were used to compare the performance of the studied samples. Proximate analytical data, organic compositions, elementary composition, and calorific value of the samples were determined. The relationship between combustion performance and sludge composition was also investigated. Results showed that the performance of sludge combustion was significantly affected by the concentration of protein, which is the main component of volatiles. Carbohydrates and lipids were not correlated with combustion performance, unlike protein. Overall, combustion performance varied with different sludge organic composition. The combustion rate of carbohydrates was higher than those of protein and lipid, and carbohydrate weight loss mainly occurred during the second stage (175–300 °C). Carbohydrates have a substantial effect on the rate of system combustion during the second stage considering the specific combustion feature. Additionally, the combustion performance of digested sewage sludge is more negative than the others

  5. Consequences of sludge composition on combustion performance derived from thermogravimetry analysis

    Energy Technology Data Exchange (ETDEWEB)

    Li, Meiyan; Xiao, Benyi; Wang, Xu; Liu, Junxin, E-mail: jxliu@rcees.ac.cn

    2015-01-15

    Highlights: • Volatiles, particularly proteins, play a key role in sludge combustion. • Sludge combustion performance varies with different sludge organic concentrations. • Carbohydrates significantly affect the combustion rate in the second stage. • Combustion performance of digested sludge is more negative compared with others. - Abstract: Wastewater treatment plants produce millions of tons of sewage sludge. Sewage sludge is recognized as a promising feedstock for power generation via combustion and can be used for energy crisis adaption. We aimed to investigate the quantitative effects of various sludge characteristics on the overall sludge combustion process performance. Different types of sewage sludge were derived from numerous wastewater treatment plants in Beijing for further thermogravimetric analysis. Thermogravimetric–differential thermogravimetric curves were used to compare the performance of the studied samples. Proximate analytical data, organic compositions, elementary composition, and calorific value of the samples were determined. The relationship between combustion performance and sludge composition was also investigated. Results showed that the performance of sludge combustion was significantly affected by the concentration of protein, which is the main component of volatiles. Carbohydrates and lipids were not correlated with combustion performance, unlike protein. Overall, combustion performance varied with different sludge organic composition. The combustion rate of carbohydrates was higher than those of protein and lipid, and carbohydrate weight loss mainly occurred during the second stage (175–300 °C). Carbohydrates have a substantial effect on the rate of system combustion during the second stage considering the specific combustion feature. Additionally, the combustion performance of digested sewage sludge is more negative than the others.

  6. Visco-piezo-elastic parameter estimation in laminated plate structures

    DEFF Research Database (Denmark)

    Araujo, A. L.; Mota Soares, C. M.; Herskovits, J.

    2009-01-01

    A parameter estimation technique is presented in this article, for identification of elastic, piezoelectric and viscoelastic properties of active laminated composite plates with surface-bonded piezoelectric patches. The inverse method presented uses experimental data in the form of a set of measu...

  7. Lower blastocyst quality after conventional vs. Piezo ICSI in the horse reflects delayed sperm component remodeling and oocyte activation.

    Science.gov (United States)

    Salgado, R M; Brom-de-Luna, J G; Resende, H L; Canesin, H S; Hinrichs, Katrin

    2018-04-10

    The aim of this study was to evaluate the differential effects of conventional and Piezo-driven ICSI on blastocyst development, and on sperm component remodeling and oocyte activation, in an equine model. In vitro-matured equine oocytes underwent conventional (Conv) or Piezo ICSI, the latter utilizing fluorocarbon ballast. Blastocyst development was compared between treatments to validate the model. Then, oocytes were fixed at 0, 6, or 18 h after injection, and stained for the sperm tail, acrosome, oocyte cortical granules, and chromatin. These parameters were compared between injection techniques and between sham-injected and sperm-injected oocytes among time periods. Blastocyst rates were 39 and 40%. The nucleus number was lower, and the nuclear fragmentation rate was higher, in blastocysts produced by Conv. Cortical granule loss started at 0H after both sperm and sham injection. The acrosome was present at 0H in both ICSI treatments, and persisted to 18H in significantly more Conv than Piezo oocytes (72 vs. 21%). Sperm head area was unchanged at 6H in Conv but significantly increased at this time in Piezo; correspondingly, at 6H significantly more Conv than Piezo oocytes remained at MII (80 vs. 9.5%). Sham injection did not induce significant meiotic resumption. These data show that Piezo ICSI is associated with more rapid sperm component remodeling and oocyte meiotic resumption after sperm injection than is conventional ICSI, and with higher embryo quality at the blastocyst stage. This suggests that there is value in exploring the Piezo technique, utilized with a non-toxic fluorocarbon ballast, for use in clinical human ICSI.

  8. Mechanical performance of hemp fiber polypropylene composites at different operating temperatures

    Science.gov (United States)

    Mehdi Tajvidi; Nazanin Motie; Ghonche Rassam; Robert H. Falk; Colin Felton

    2010-01-01

    In order to quantify the effect of temperature on the mechanical properties of hemp fiber polypropylene composites, formulations containing 25% and 40% (by weight) hemp fiber were produced and tested at three representative temperatures of 256, 296, and 336 K. Flexural, tensile, and impact tests, as well as dynamic mechanical analysis, were performed and the reduction...

  9. Electrochemical performance of polypyrrole/silver vanadium oxide composite cathodes in lithium primary batteries

    Science.gov (United States)

    Anguchamy, Yogesh K.; Lee, Jong-Won; Popov, Branko N.

    Polypyrrole (PPy)/silver vanadium oxide (SVO) composite cathode materials were synthesized by polymerizing pyrrole onto the surface of pure SVO particles. Electrochemical characterization was carried out by performing galvanostatic discharge, pulse discharge and ac-impedance experiments. The composite electrode exhibited better performance than pristine SVO in all the experiments. The composite electrodes yielded a higher discharge capacity and a better pulse discharge capability when compared to the pristine SVO electrode. The pulse discharge and ac-impedance studies indicated that PPy forms an effective conductive network on the SVO surface and thereby reduces the particle-to-particle contact resistance and facilitates the interfacial charge transfer kinetics. To determine the thermal stability of the composite cathode, galvanostatic discharge and ac-impedance experiments were performed at different temperatures. The capacity increased with temperature due to enhanced charge transfer kinetics and low mass transfer limitations. The peak capacity was obtained at 60 °C, after which the performance degraded with any further increase in temperature.

  10. Electrochemical performance of polypyrrole/silver vanadium oxide composite cathodes in lithium primary batteries

    Energy Technology Data Exchange (ETDEWEB)

    Anguchamy, Yogesh K.; Lee, Jong-Won; Popov, Branko N. [Center for Electrochemical Engineering, Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208 (United States)

    2008-09-15

    Polypyrrole (PPy)/silver vanadium oxide (SVO) composite cathode materials were synthesized by polymerizing pyrrole onto the surface of pure SVO particles. Electrochemical characterization was carried out by performing galvanostatic discharge, pulse discharge and ac-impedance experiments. The composite electrode exhibited better performance than pristine SVO in all the experiments. The composite electrodes yielded a higher discharge capacity and a better pulse discharge capability when compared to the pristine SVO electrode. The pulse discharge and ac-impedance studies indicated that PPy forms an effective conductive network on the SVO surface and thereby reduces the particle-to-particle contact resistance and facilitates the interfacial charge transfer kinetics. To determine the thermal stability of the composite cathode, galvanostatic discharge and ac-impedance experiments were performed at different temperatures. The capacity increased with temperature due to enhanced charge transfer kinetics and low mass transfer limitations. The peak capacity was obtained at 60 C, after which the performance degraded with any further increase in temperature. (author)

  11. The Apperception of Musical Creativity: Performance as Ritual, Composition as Self-Realization

    Science.gov (United States)

    Nagy, Zvonimir

    2015-01-01

    Musical invention is defined in this article as a form of inward creativity. The creative acts of musical performance are understood in terms of ritual-like symbolic and stylized actions, and those of musical composition as the mind's enactment of meditation and reflection. This article draws on the relationship between two psychological…

  12. High Performance Li4Ti5O12/Si Composite Anodes for Li-Ion Batteries

    Directory of Open Access Journals (Sweden)

    Chunhui Chen

    2015-08-01

    Full Text Available Improving the energy capacity of spinel Li4Ti5O12 (LTO is very important to utilize it as a high-performance Li-ion battery (LIB electrode. In this work, LTO/Si composites with different weight ratios were prepared and tested as anodes. The anodic and cathodic peaks from both LTO and silicon were apparent in the composites, indicating that each component was active upon Li+ insertion and extraction. The composites with higher Si contents (LTO:Si = 35:35 exhibited superior specific capacity (1004 mAh·g−1 at lower current densities (0.22 A·g−1 but the capacity deteriorated at higher current densities. On the other hand, the electrodes with moderate Si contents (LTO:Si = 50:20 were able to deliver stable capacity (100 mAh·g−1 with good cycling performance, even at a very high current density of 7 A·g−1. The improvement in specific capacity and rate performance was a direct result of the synergy between LTO and Si; the former can alleviate the stresses from volumetric changes in Si upon cycling, while Si can add to the capacity of the composite. Therefore, it has been demonstrated that the addition of Si and concentration optimization is an easy yet an effective way to produce high performance LTO-based electrodes for lithium-ion batteries.

  13. Short Circuits or Superconductors? Effects of Group Composition on High-Achieving Students' Science Assessment Performance.

    Science.gov (United States)

    Webb, Noreen M.; Nemer, Kariane Mari; Zuniga, Stephen

    2002-01-01

    Studied the effects of group ability composition (homogeneous versus heterogeneous) on group processes and outcomes for high-ability students completing science assessments. Results for 83 high ability students show the quality of group functioning serves as the strongest predictor of high-ability students' performance and explained much of the…

  14. Moisture Performance of wood-plastic composites reinforced with extracted and delignified wood flour

    Science.gov (United States)

    Yao Chen; Nicole M. Stark; Mandla A. Tshabalala; Jianmin Gao; Yongming Fan

    2014-01-01

    This study investigated the effect of using extracted and delignified wood flour on water sorption properties of wood–plastic composites. Wood flour (WF) extraction was performed with three solvent systems: toluene/ethanol (TE), acetone/water (AW), and hot water (HW); delignification was conducted using sodium chlorite/acetic acid solution. A 24 full-factorial...

  15. A Temperature Compensation Method for Piezo-Resistive Pressure Sensor Utilizing Chaotic Ions Motion Algorithm Optimized Hybrid Kernel LSSVM

    Directory of Open Access Journals (Sweden)

    Ji Li

    2016-10-01

    Full Text Available A piezo-resistive pressure sensor is made of silicon, the nature of which is considerably influenced by ambient temperature. The effect of temperature should be eliminated during the working period in expectation of linear output. To deal with this issue, an approach consists of a hybrid kernel Least Squares Support Vector Machine (LSSVM optimized by a chaotic ions motion algorithm presented. To achieve the learning and generalization for excellent performance, a hybrid kernel function, constructed by a local kernel as Radial Basis Function (RBF kernel, and a global kernel as polynomial kernel is incorporated into the Least Squares Support Vector Machine. The chaotic ions motion algorithm is introduced to find the best hyper-parameters of the Least Squares Support Vector Machine. The temperature data from a calibration experiment is conducted to validate the proposed method. With attention on algorithm robustness and engineering applications, the compensation result shows the proposed scheme outperforms other compared methods on several performance measures as maximum absolute relative error, minimum absolute relative error mean and variance of the averaged value on fifty runs. Furthermore, the proposed temperature compensation approach lays a foundation for more extensive research.

  16. A Temperature Compensation Method for Piezo-Resistive Pressure Sensor Utilizing Chaotic Ions Motion Algorithm Optimized Hybrid Kernel LSSVM.

    Science.gov (United States)

    Li, Ji; Hu, Guoqing; Zhou, Yonghong; Zou, Chong; Peng, Wei; Alam Sm, Jahangir

    2016-10-14

    A piezo-resistive pressure sensor is made of silicon, the nature of which is considerably influenced by ambient temperature. The effect of temperature should be eliminated during the working period in expectation of linear output. To deal with this issue, an approach consists of a hybrid kernel Least Squares Support Vector Machine (LSSVM) optimized by a chaotic ions motion algorithm presented. To achieve the learning and generalization for excellent performance, a hybrid kernel function, constructed by a local kernel as Radial Basis Function (RBF) kernel, and a global kernel as polynomial kernel is incorporated into the Least Squares Support Vector Machine. The chaotic ions motion algorithm is introduced to find the best hyper-parameters of the Least Squares Support Vector Machine. The temperature data from a calibration experiment is conducted to validate the proposed method. With attention on algorithm robustness and engineering applications, the compensation result shows the proposed scheme outperforms other compared methods on several performance measures as maximum absolute relative error, minimum absolute relative error mean and variance of the averaged value on fifty runs. Furthermore, the proposed temperature compensation approach lays a foundation for more extensive research.

  17. Synthesis and electrochemical performance of polyaniline-MnO2 nanowire composites for supercapacitors

    Science.gov (United States)

    Chen, Ling; Song, Zhaoxia; Liu, Guichang; Qiu, Jieshan; Yu, Chang; Qin, Jiwei; Ma, Lin; Tian, Fengqin; Liu, Wei

    2013-02-01

    Polyaniline-MnO2 nanowire (PANI-MNW) composites were prepared by in situ chemical oxidative polymerization of aniline monomer in a suspension of MnO2 nanowires. The structure and morphology of the PANI-MNW composites were characterized by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). Their electrochemical properties were investigated using cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy in 1 mol/L KOH electrolyte. The PANI-MNW composites show significantly better specific capacity and redox performance in comparison to the untreated MnO2 nanowires. The enhanced properties can be mainly attributed to the composite structure wherein high porosity is created between MnO2 nanowires and PANI during the process of fabricating the PANI-MNW nanocomposites. A specific capacitance as high as 256 F/g is obtained at a current density of 1 A/g for PANI-MNW-5, and the composite also shows a good cyclic performance and coulomb efficiency.

  18. Design and Optimization of Composite Automotive Hatchback Using Integrated Material-Structure-Process-Performance Method

    Science.gov (United States)

    Yang, Xudong; Sun, Lingyu; Zhang, Cheng; Li, Lijun; Dai, Zongmiao; Xiong, Zhenkai

    2018-03-01

    The application of polymer composites as a substitution of metal is an effective approach to reduce vehicle weight. However, the final performance of composite structures is determined not only by the material types, structural designs and manufacturing process, but also by their mutual restrict. Hence, an integrated "material-structure-process-performance" method is proposed for the conceptual and detail design of composite components. The material selection is based on the principle of composite mechanics such as rule of mixture for laminate. The design of component geometry, dimension and stacking sequence is determined by parametric modeling and size optimization. The selection of process parameters are based on multi-physical field simulation. The stiffness and modal constraint conditions were obtained from the numerical analysis of metal benchmark under typical load conditions. The optimal design was found by multi-discipline optimization. Finally, the proposed method was validated by an application case of automotive hatchback using carbon fiber reinforced polymer. Compared with the metal benchmark, the weight of composite one reduces 38.8%, simultaneously, its torsion and bending stiffness increases 3.75% and 33.23%, respectively, and the first frequency also increases 44.78%.

  19. Understanding the Enhanced Catalytic Performance of Ultrafine Transition Metal Nanoparticles–Graphene Composites

    KAUST Repository

    Liu, Xin

    2015-08-11

    Catalysis, as the key to minimize the energy requirement and environmental impact of today\\'s chemical industry, plays a vital role in many fields directly related to our daily life and economy, including energy generation, environment control, manufacture of chemicals, medicine synthesis, etc. Rational design and fabrication of highly efficient catalysts have become the ultimate goal of today\\'s catalysis research. For the purpose of handling and product separation, heterogeneous catalysts are highly preferred for industrial applications and a large part of which are the composites of transition metal nanoparticles (TMNPs). With the fast development of nanoscience and nanotechnology and assisted with theoretical investigations, basic understanding on tailoring the electronic structure of these nanocomposites has been gained, mainly by precise control of the composition, morphology, interfacial structure and electronic states. With the rise of graphene, chemical routes to prepare graphene were developed and various graphene-based composites were fabricated. Transition metal nanoparticles-reduced graphene oxide (TMNPs–rGO) composites have attracted considerable attention, because of their intriguing catalytic performance which have been extensively explored for energy- and environment-related applications to date. This review summarizes our recent experimental and theoretical efforts on understanding the superior catalytic performance of subnanosized TMNPs–rGO composites.

  20. NiO/nanoporous graphene composites with excellent supercapacitive performance produced by atomic layer deposition

    International Nuclear Information System (INIS)

    Chen, Caiying; Chen, Chaoqiu; Duan, Feifei; Zhao, Shichao; Qin, Yong; Huang, Peipei; Li, Ping; Fan, Jinchuan; Song, Weiguo

    2014-01-01

    Nickel oxide (NiO) is a promising electrode material for supercapacitors because of its low cost and high theoretical specific capacitance of 2573 F g −1 . However, the low electronic conductivity and poor cycling stability of NiO limit its practical applications. To overcome these limitations, an efficient atomic layer deposition (ALD) method is demonstrated here for the fabrication of NiO/nanoporous graphene (NG) composites as electrode materials for supercapacitors. ALD allows uniform deposition of NiO nanoparticles with controlled sizes on the surface of NG, thus offering a novel route to design NiO/NG composites for supercapacitor applications with high surface areas and greatly improved electrical conductivity and cycle stability. Electrochemical measurements reveal that the NiO/NG composites obtained by ALD exhibited excellent specific capacitance of up to ∼1005.8 F g −1 per mass of the composite electrode (the specific capacitance value is up to ∼1897.1 F g −1 based on the active mass of NiO), and stable performance after 1500 cycles. Furthermore, electrochemical performance of the NiO/NG composites is found to strongly depend on the size of NiO nanoparticles. (paper)

  1. Sulfur nanocrystals anchored graphene composite with highly improved electrochemical performance for lithium-sulfur batteries

    Science.gov (United States)

    Zhang, Jun; Dong, Zimin; Wang, Xiuli; Zhao, Xuyang; Tu, Jiangping; Su, Qingmei; Du, Gaohui

    2014-12-01

    Two kinds of graphene-sulfur composites with 50 wt% of sulfur are prepared using hydrothermal method and thermal mixing, respectively. Transmission Electron Microscopy (TEM) and Energy Dispersive X-ray Spectra mapping show that sulfur nanocrystals with size of ∼5 nm dispersed on graphene sheets homogeneously for the sample prepared by hydrothermal method (NanoS@G). While for the thermal mixed graphene-sulfur composite (S-G mixture), sulfur shows larger and uneven size (50-200 nm). X-ray Photoelectron Spectra (XPS) reveals the strong chemical bonding between the sulfur nanocrystals and graphene. Comparing with the S-G mixture, the NanoS@G composite shows highly improved electrochemical performance as cathode for lithium-sulfur (Li-S) battery. The NanoS@G composite delivers an initial capacity of 1400 mAh g-1 with the sulfur utilization of 83.7% at a current density of 335 mA g-1. The capacity keeps above 720 mAh g-1 over 100 cycles. The strong adherence of the sulfur nanocrystals on graphene immobilizes sulfur and polysulfides species and suppressed the "shuttle effect", resulting higher coulombic efficiency and better capacity retention. Electrochemical impedance also suggests that the strong bonding enabled rapid electronic/ionic transport and improved electrochemical kinetics, therefore good rate capability is obtained. These results demonstrate that the NanoS@G composite is a very promising candidate for high-performance Li-S batteries.

  2. UiO-66-NH2/GO Composite: Synthesis, Characterization and CO2 Adsorption Performance

    Directory of Open Access Journals (Sweden)

    Yan Cao

    2018-04-01

    Full Text Available In this work, a new composite materials of graphene oxide (GO-incorporated metal-organic framework (MOF(UiO-66-NH2/GO were in-situ synthesized, and were found to exhibit enhanced high performances for CO2 capture. X-ray diffraction (XRD, scanning electron microscope (SEM, N2 physical adsorption, and thermogravimetric analysis (TGA were applied to investigate the crystalline structure, pore structure, thermal stability, and the exterior morphology of the composite. We aimed to investigate the influence of the introduction of GO on the stability of the crystal skeleton and pore structure. Water, acid, and alkali resistances were tested for physical and chemical properties of the new composites. CO2 adsorption isotherms of UiO-66, UiO-66-NH2, UiO-66/GO, and UiO-66-NH2/GO were measured at 273 K, 298 K, and 318 K. The composite UiO-66-NH2/GO exhibited better optimized CO2 uptake of 6.41 mmol/g at 273 K, which was 5.1% higher than that of UiO-66/GO (6.10 mmol/g. CO2 adsorption heat and CO2/N2 selectivity were then calculated to further evaluate the CO2 adsorption performance. The results indicated that UiO-66-NH2/GO composites have a potential application in CO2 capture technologies to alleviate the increase in temperature of the earth’s atmosphere.

  3. Thermal performance enhancement of erythritol/carbon foam composites via surface modification of carbon foam

    Science.gov (United States)

    Li, Junfeng; Lu, Wu; Luo, Zhengping; Zeng, Yibing

    2017-03-01

    The thermal performance of the erythritol/carbon foam composites, including thermal diffusivity, thermal capacity, thermal conductivity and latent heat, were investigated via surface modification of carbon foam using hydrogen peroxide as oxider. It was found that the surface modification enhanced the wetting ability of carbon foam surface to the liquid erythritol of the carbon foam surface and promoted the increase of erythritol content in the erythritol/carbon foam composites. The dense interfaces were formed between erythritol and carbon foam, which is due to that the formation of oxygen functional groups C=O and C-OH on the carbon surface increased the surface polarity and reduced the interface resistance of carbon foam surface to the liquid erythritol. The latent heat of the erythritol/carbon foam composites increased from 202.0 to 217.2 J/g through surface modification of carbon foam. The thermal conductivity of the erythritol/carbon foam composite before and after surface modification further increased from 40.35 to 51.05 W/(m·K). The supercooling degree of erythritol also had a large decrease from 97 to 54 °C. Additionally, the simple and effective surface modification method of carbon foam provided an extendable way to enhance the thermal performances of the composites composed of carbon foams and PCMs.

  4. Performance evaluation of CNT/polypyrrole/MnO2 composite electrodes for electrochemical capacitors

    International Nuclear Information System (INIS)

    Sivakkumar, S.R.; Ko, Jang Myoun; Kim, Dong Young; Kim, B.C.; Wallace, G.G.

    2007-01-01

    A ternary composite of CNT/polypyrrole/hydrous MnO 2 is prepared by in situ chemical method and its electrochemical performance is evaluated by using cyclic voltammetry (CV), impedance measurement and constant-current charge/discharge cycling techniques. For comparative purpose, binary composites such as CNT/hydrous MnO 2 and polypyrrole/hydrous MnO 2 are prepared and also investigated for their physical and electrochemical performances. The specific capacitance (SC) values of the ternary composite, CNT/hydrous MnO 2 and polypyrrole/hydrous MnO 2 binary composites estimated by CV technique in 1.0 M Na 2 SO 4 electrolyte are 281, 150 and 35 F g -1 at 20 mV s -1 and 209, 75 and 7 F g -1 at 200 mV s -1 , respectively. The electrochemical stability of ternary composite electrode is investigated by switching the electrode back and forth for 10,000 times between 0.1 and 0.9 V versus Ag/AgCl at 100 mV s -1 . The electrode exhibits good cycling stability, retaining up to 88% of its initial charge at 10,000th cycle. A full cell assembled with the ternary composite electrodes shows a SC value of 149 F g -1 at a current loading of 1.0 mA cm -2 during initial cycling, which decreased drastically to a value of 35 F g -1 at 2000th cycle. Analytical techniques such as scanning electron microscopy (SEM), X-ray diffraction spectroscopy (XRD), Brunauer-Emmet-Teller (BET) surface area measurement and inductively coupled plasma-atomic emission spectrometry (ICP-AES) are also used to characterize the composite materials

  5. Performance evaluation of CNT/polypyrrole/MnO{sub 2} composite electrodes for electrochemical capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Sivakkumar, S.R. [Department of Applied Chemistry and Biotechnology, Hanbat National University, San 16-1, Dukmyung-Dong, Yusung-Gu, Daejeon 305-719 (Korea, Republic of); Ko, Jang Myoun [Department of Applied Chemistry and Biotechnology, Hanbat National University, San 16-1, Dukmyung-Dong, Yusung-Gu, Daejeon 305-719 (Korea, Republic of)]. E-mail: jmko@hanbat.ac.kr; Kim, Dong Young [Optoelectronic Materials Research Center, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650 (Korea, Republic of); Kim, B.C. [ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia); Wallace, G.G. [ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia)

    2007-09-15

    A ternary composite of CNT/polypyrrole/hydrous MnO{sub 2} is prepared by in situ chemical method and its electrochemical performance is evaluated by using cyclic voltammetry (CV), impedance measurement and constant-current charge/discharge cycling techniques. For comparative purpose, binary composites such as CNT/hydrous MnO{sub 2} and polypyrrole/hydrous MnO{sub 2} are prepared and also investigated for their physical and electrochemical performances. The specific capacitance (SC) values of the ternary composite, CNT/hydrous MnO{sub 2} and polypyrrole/hydrous MnO{sub 2} binary composites estimated by CV technique in 1.0 M Na{sub 2}SO{sub 4} electrolyte are 281, 150 and 35 F g{sup -1} at 20 mV s{sup -1} and 209, 75 and 7 F g{sup -1} at 200 mV s{sup -1}, respectively. The electrochemical stability of ternary composite electrode is investigated by switching the electrode back and forth for 10,000 times between 0.1 and 0.9 V versus Ag/AgCl at 100 mV s{sup -1}. The electrode exhibits good cycling stability, retaining up to 88% of its initial charge at 10,000th cycle. A full cell assembled with the ternary composite electrodes shows a SC value of 149 F g{sup -1} at a current loading of 1.0 mA cm{sup -2} during initial cycling, which decreased drastically to a value of 35 F g{sup -1} at 2000th cycle. Analytical techniques such as scanning electron microscopy (SEM), X-ray diffraction spectroscopy (XRD), Brunauer-Emmet-Teller (BET) surface area measurement and inductively coupled plasma-atomic emission spectrometry (ICP-AES) are also used to characterize the composite materials.

  6. High performance natural rubber composites with a hierarchical reinforcement structure of carbon nanotube modified natural fibers

    International Nuclear Information System (INIS)

    Tzounis, Lazaros; Debnath, Subhas; Rooj, Sandip; Fischer, Dieter; Mäder, Edith; Das, Amit; Stamm, Manfred; Heinrich, Gert

    2014-01-01

    A simple and facile method for depositing multiwall carbon nanotubes (MWCNTs) onto the surface of naturally occurring short jute fibers (JFs) is reported. Hierarchical multi-scale structures were formed with CNT-networks uniformly distributed and fully covering the JFs (JF–CNT), as depicted by the scanning electron microscopy (SEM) micrographs. The impact of these hybrid fillers on the mechanical properties of a natural rubber (NR) matrix was systematically investigated. Pristine JFs were cut initially to an average length of 2.0 mm and exposed to an alkali treatment (a-JFs) to remove impurities existing in the raw jute. MWCNTs were treated under mild acidic conditions to generate carboxylic acid moieties. Afterward, MWCNTs were dispersed in an aqueous media and short a-JFs were allowed to react with them. Raman spectroscopy confirmed the chemical interaction between CNTs and JFs. The JF–CNT exposed quite hydrophobic behavior as revealed by the water contact angle measurements, improving the wettability of the non-polar NR. Consequently, the composite interfacial adhesion strength was significantly enhanced while a micro-scale “mechanical interlocking” mechanism was observed from the interphase-section transmission electron microscopy (TEM) images. SEM analysis of the composite fracture surfaces demonstrated the interfacial strength of NR/a-JF and NR/JF–CNT composites, at different fiber loadings. It can be presumed that the CNT-coating effectively compatibillized the composite structure acting as a macromolecular coupling agent. A detailed analysis of stress-strain and dynamic mechanical spectra confirmed the high mechanical performance of the hierarchical composites, consisting mainly of materials arising from natural resources. - Highlights: • Natural rubber (NR) composites reinforced with CNT-modified short jute fibers. • MWCNTs deposited to the surface of jute fibers via non-covalent interactions. • Hierarchical reinforcement structure with

  7. Synthesis and Performance of Tungsten Disulfide/Carbon (WS2/C) Composite as Anode Material

    Science.gov (United States)

    Yuan, Zhengyong; Jiang, Qiang; Feng, Chuanqi; Chen, Xiao; Guo, Zaiping

    2018-01-01

    The precursors of an amorphous WS2/C composite were synthesized by a simple hydrothermal method using Na2WO4·2H2O and CH3CSNH2 as raw materials, polyethylene glycol as dispersant, and glucose as the carbon source. The as-synthesized precursors were further annealed at a low temperature in flowing argon to obtain the final materials (WS2/C composite). The structure and morphology of the WS2/C composite were characterized by x-ray diffraction, x-ray photoelectron spectroscopy, and scanning electron microscopy. The electrochemical properties were tested by galvanostatic charge/discharge testing and alternating current (AC) impedance measurements. The results show that the as-prepared amorphous WS2/C composite features both high specific capacity and good cycling performance at room temperature within the potential window from 3.0 V to 0.01 V (versus Li+/Li) at current density of 100 mAg-1. The achieved initial discharge capacity was 1080 mAhg-1, and 786 mAhg-1 was retained after 170 cycles. Furthermore, the amorphous WS2/C composite exhibited a lower charge/discharge plateau than bare WS2, which is more beneficial for use as an anode. The cyclic voltammetry and AC impedance testing further confirmed the change in the plateau and the decrease in the charge transfer resistance in the WS2/C composite. The chemical formation process and the electrochemical mechanism of the WS2/C composite are also presented. The amorphous WS2/C composite can be used as a new anode material for future applications.

  8. Synergistic effect of tungsten disulfide and cenosphere combination on braking performance of composite friction materials

    International Nuclear Information System (INIS)

    Kachhap, Rakesh K.; Satapathy, Bhabani K.

    2014-01-01

    Graphical abstract: Graphical abstract showing correlation between enhanced frictional stability and enhanced visc-oelastic energy dissipation. - Highlights: • Developed new class of brake composites based on WS 2 and cenosphere. • Synergistic effect of WS 2 and cenosphere for enhanced friction stability. • Wear surface morphology revealed composition specific topography. • Friction fade-recovery performance remained optimal. - Abstract: Tungsten disulfide (WS 2 /TDS) based cenosphere (Cn) filled friction composites with varying cenosphere to WS 2 ratio (Cn/TDS) were fabricated by compression molding of phenolic resin based dry formulation mix and evaluated for their thermal, thermo-mechanical and tribological performances. The loss and revival of braking friction effectiveness due to heating or cooling of the disc termed as fade and recovery performance have been characterized on a Krauss friction testing machine following ECE R-90 industrial standards. The fade performance remained dependent on Cn/TDS, where enhanced fading could be correlated to lower Cn/TDS value accompanied with broader frictional fluctuations i.e. μ max –μ min . A decrease in the frictional-recovery response ensued with increase in Cn/TDS. Dynamic mechanical analysis revealed an increase in storage modulus till 2.5 wt.% of TDS loading followed by consistent decrease whereas two distinct peaks in loss modulus plots that are composition independent have been observed. Scanning electron microscopy revealed the worn surface morphology associated with the dynamics of contact patches formation and deformation vis-a-vis friction layer formation as integrally responsible for the observed friction performance. Energy dispersive analysis of X-rays (EDX) enabled compositional analysis of the friction layer viz. Fe, W, Si, and Al content which may have a mechanistic role in controlling phenomena like, disc rubbing, lubricity, porosity, and hardness of friction layer formed during braking

  9. Composite and Cascaded Generalized-K Fading Channel Modeling and Their Diversity and Performance Analysis

    KAUST Repository

    Ansari, Imran Shafique

    2010-12-01

    The introduction of new schemes that are based on the communication among nodes has motivated the use of composite fading models due to the fact that the nodes experience different multipath fading and shadowing statistics, which subsequently determines the required statistics for the performance analysis of different transceivers. The end-to-end signal-to-noise-ratio (SNR) statistics plays an essential role in the determination of the performance of cascaded digital communication systems. In this thesis, a closed-form expression for the probability density function (PDF) of the end-end SNR for independent but not necessarily identically distributed (i.n.i.d.) cascaded generalized-K (GK) composite fading channels is derived. The developed PDF expression in terms of the Meijer-G function allows the derivation of subsequent performance metrics, applicable to different modulation schemes, including outage probability, bit error rate for coherent as well as non-coherent systems, and average channel capacity that provides insights into the performance of a digital communication system operating in N cascaded GK composite fading environment. Another line of research that was motivated by the introduction of composite fading channels is the error performance. Error performance is one of the main performance measures and derivation of its closed-form expression has proved to be quite involved for certain systems. Hence, in this thesis, a unified closed-form expression, applicable to different binary modulation schemes, for the bit error rate of dual-branch selection diversity based systems undergoing i.n.i.d. GK fading is derived in terms of the extended generalized bivariate Meijer G-function.

  10. Circadian phenotype composition is a major predictor of diurnal physical performance in teams

    Directory of Open Access Journals (Sweden)

    Elise Rose Facer-Childs

    2015-10-01

    Full Text Available Team performance is a complex phenomenon involving numerous influencing factors including physiology, psychology, and management. Biological rhythms and the impact of circadian phenotype have not been studied for their contribution to this array of factors so far despite our knowledge of the circadian regulation of key physiological processes involved in physical and mental performance. This study involved 216 individuals from 12 different teams who were categorized into circadian phenotypes using the novel RBUB chronometric test. The composition of circadian phenotypes within each team was used to model predicted daily team performance profiles based on physical performance tests. Our results show that the composition of circadian phenotypes within teams is variable and unpredictable. Predicted physical peak performance ranged from 1.52pm to 8.59pm with performance levels fluctuating by up to 14.88% over the course of the day. The major predictor for peak performance time of day in a team is the occurrence of late circadian phenotypes. We conclude that circadian phenotype is a performance indicator in teams that allows new insight and a better understanding of team performance variation in the course of a day as often observed in different groupings of individuals.

  11. Circadian Phenotype Composition is a Major Predictor of Diurnal Physical Performance in Teams.

    Science.gov (United States)

    Facer-Childs, Elise; Brandstaetter, Roland

    2015-01-01

    Team performance is a complex phenomenon involving numerous influencing factors including physiology, psychology, and management. Biological rhythms and the impact of circadian phenotype have not been studied for their contribution to this array of factors so far despite our knowledge of the circadian regulation of key physiological processes involved in physical and mental performance. This study involved 216 individuals from 12 different teams who were categorized into circadian phenotypes using the novel RBUB chronometric test. The composition of circadian phenotypes within each team was used to model predicted daily team performance profiles based on physical performance tests. Our results show that the composition of circadian phenotypes within teams is variable and unpredictable. Predicted physical peak performance ranged from 1:52 to 8:59 p.m. with performance levels fluctuating by up to 14.88% over the course of the day. The major predictor for peak performance time in the course of a day in a team is the occurrence of late circadian phenotypes. We conclude that circadian phenotype is a performance indicator in teams that allows new insight and a better understanding of team performance variation in the course of a day as often observed in different groupings of individuals.

  12. Study on Electrochemical Performance of Carbonnanotubes/Fey 04 Composite Electrode Material

    Directory of Open Access Journals (Sweden)

    WANG Fang--yong

    2017-02-01

    Full Text Available For single super capacitor materials,each material has its own unique advantages and defects. In this paper, the synthesis of complex multi walled carbon nanotubes with Fe304 nanoparticles by simple hydrothermal method. Composite performance for Fe3 OQ nanoparticles adsorbed on carbon nano tube wall composed of reticular structure morphology. Synergy of two component,provides the binary nanometer compound larger specific capacity, excellent properties and good cycle stability. The experimental results proved that the improvement effects of CNT carbon materials on the electrochemical properties of pseudocapacitive electrode material,and CNT/Fe3 OQ nano- composites applied to supercapacitor electrode material.

  13. Effect of glass microfibre addition on the mechanical performances of fly ash-based geopolymer composites

    Directory of Open Access Journals (Sweden)

    Thamer Alomayri

    2017-09-01

    Full Text Available In the present study, various amounts of glass microfibres were introduced into a geopolymer for reinforcement purposes. The influence of these microfibres on the performance of the geopolymer composites was investigated. Results show that the appropriate addition of glass microfibres can improve the mechanical properties of geopolymer composites. In particular, the flexural strength, flexural modulus and impact strength increase at an optimum fibre content of 2 wt%. Further, adding glass microfibres to a plain geopolymer matrix has a significant effect on the pre-cracking behaviour. It substantially enhances the post-cracking response.

  14. Impact of gender and ethnic composition of South African boards of directors on intellectual capital performance

    Directory of Open Access Journals (Sweden)

    J-L. W. Mitchell Van der Zahn

    2006-01-01

    Full Text Available This study examines the association between the gender and ethnic composition of boards of directors and firm performance in a transitional nation. In contrast to prior research that largely focuses on firm performance within a financial context, this study concentrates on intellectual capital performance. Using data collected from 84 South African, empirical results indicate a positive association between the percentage of female and non-white directors on the board and a firm’s intellectual capital performance. Additional analysis shows the designation of female directors as an insider has a negative effect of intellectual capital performance. Designation of female and non-white directors as outsiders, meanwhile, has a positive influence on a firm’s intellectual capital performance. Finally, there was no association between the percentage of non-white inside directors on the board and intellectual capital performance.

  15. A State of the Art Review- Methods to Evaluate Electrical Performance of Composite Cross-arms and Composite-based Pylons

    DEFF Research Database (Denmark)

    Wang, Qian; Bak, Claus Leth; Silva, Filipe Miguel Faria da

    2016-01-01

    A novel uni-body composite pylon has been proposed for 400 kV transmission lines with advantages of compacted size, friendly looking and cost competitiveness. As its configuration is quite different from the traditional lattice pylon, its electrical performance needs in-depth investigation...... and evaluation, for which electrical testing methods are essential. However, as research on composite-based pylons is still in initial stage, leaving international standards and theoretical analysis on this topic very limited, effective testing methods to evaluate the fully composite pylon’s electrical...... performance need to be studied. This paper sums up experience and key advances on testing methods to evaluate electrical performance of composite cross-arms and composite-based pylons. Based on state of the art review, several feasible testing methods that can be used to verify the feasibility of the novel...

  16. Excellent Temperature Performance of Spherical LiFePO4/C Composites Modified with Composite Carbon and Metal Oxides

    Directory of Open Access Journals (Sweden)

    Bao Zhang

    2014-01-01

    Full Text Available Nanosized spherical LiFePO4/C composite was synthesized from nanosized spherical FePO4·2H2O, Li2C2O4, aluminum oxide, titanium oxide, oxalic acid, and sucrose by binary sintering process. The phases and morphologies of LiFePO4/C were characterized using SEM, TEM, CV, EIS, EDS, and EDX as well as charging and discharging measurements. The results showed that the as-prepared LiFePO4/C composite with good conductive webs from nanosized spherical FePO4·2H2O exhibits excellent electrochemical performances, delivering an initial discharge capacity of 161.7 mAh·g−1 at a 0.1 C rate, 152.4 mAh·g−1 at a 1 C rate and 131.7 mAh·g−1 at a 5 C rate, and the capacity retention of 99.1%, 98.7%, and 95.8%, respectively, after 50 cycles. Meanwhile, the high and low temperature performance is excellent for 18650 battery, maintaining capacity retention of 101.7%, 95.0%, 88.3%, and 79.3% at 55°C, 0°C, −10°C, and −20°C by comparison withthat of room temperature (25°C at the 0.5 C rate over a voltage range of 2.2 V to 3.6 V, respectively.

  17. Excellent temperature performance of spherical LiFePO4/C composites modified with composite carbon and metal oxides.

    Science.gov (United States)

    Zhang, Bao; Zeng, Tao; Zhang, Jiafeng; Peng, Chunli; Zheng, Junchao; Chen, Guomin

    2014-01-01

    Nanosized spherical LiFePO4/C composite was synthesized from nanosized spherical FePO4 ·2H2O, Li2C2O4, aluminum oxide, titanium oxide, oxalic acid, and sucrose by binary sintering process. The phases and morphologies of LiFePO4/C were characterized using SEM, TEM, CV, EIS, EDS, and EDX as well as charging and discharging measurements. The results showed that the as-prepared LiFePO4/C composite with good conductive webs from nanosized spherical FePO4 ·2H2O exhibits excellent electrochemical performances, delivering an initial discharge capacity of 161.7 mAh·g(-1) at a 0.1 C rate, 152.4 mAh·g(-1) at a 1 C rate and 131.7 mAh·g(-1) at a 5 C rate, and the capacity retention of 99.1%, 98.7%, and 95.8%, respectively, after 50 cycles. Meanwhile, the high and low temperature performance is excellent for 18650 battery, maintaining capacity retention of 101.7%, 95.0%, 88.3%, and 79.3% at 55°C, 0°C, -10°C, and -20°C by comparison withthat of room temperature (25°C) at the 0.5 C rate over a voltage range of 2.2 V to 3.6 V, respectively.

  18. Seismic Performance of Composite Shear Walls Constructed Using Recycled Aggregate Concrete and Different Expandable Polystyrene Configurations

    Directory of Open Access Journals (Sweden)

    Wenchao Liu

    2016-03-01

    Full Text Available The seismic performance of recycled aggregate concrete (RAC composite shear walls with different expandable polystyrene (EPS configurations was investigated. Six concrete shear walls were designed and tested under cyclic loading to evaluate the effect of fine RAC in designing earthquake-resistant structures. Three of the six specimens were used to construct mid-rise walls with a shear-span ratio of 1.5, and the other three specimens were used to construct low-rise walls with a shear-span ratio of 0.8. The mid-rise and low-rise shear walls consisted of an ordinary recycled concrete shear wall, a composite wall with fine aggregate concrete (FAC protective layer (EPS modules as the external insulation layer, and a composite wall with sandwiched EPS modules as the insulation layer. Several parameters obtained from the experimental results were compared and analyzed, including the load-bearing capacity, stiffness, ductility, energy dissipation, and failure characteristics of the specimens. The calculation formula of load-bearing capacity was obtained by considering the effect of FAC on composite shear walls as the protective layer. The damage process of the specimen was simulated using the ABAQUS Software, and the results agreed quite well with those obtained from the experiments. The results show that the seismic resistance behavior of the EPS module composite for shear walls performed better than ordinary recycled concrete for shear walls. Shear walls with sandwiched EPS modules had a better seismic performance than those with EPS modules lying outside. Although the FAC protective layer slightly improved the seismic performance of the structure, it undoubtedly slowed down the speed of crack formation and the stiffness degradation of the walls.

  19. Body Composition, Neuromuscular Performance, and Mobility: Comparison Between Regularly Exercising and Inactive Older Women.

    Science.gov (United States)

    Rava, Anni; Pihlak, Anu; Ereline, Jaan; Gapeyeva, Helena; Kums, Tatjana; Purge, Priit; Jürimäe, Jaak; Pääsuke, Mati

    2017-01-01

    The purpose of this study was to evaluate the differences in body composition, neuromuscular performance, and mobility in healthy, regularly exercising and inactive older women, and examine the relationship between skeletal muscle indices and mobility. Overall, 32 healthy older women participated. They were divided into groups according to their physical activity history as regularly exercising (n = 22) and inactive (n = 10) women. Body composition, hand grip strength, leg extensor muscle strength, rapid force development, power output, and mobility indices were assessed. Regularly exercising women had lower fat mass and higher values for leg extensor muscle strength and muscle quality, and also for mobility. Leg extensor muscle strength and power output during vertical jumping and appendicular lean mass per unit of body mass were associated with mobility in healthy older women. It was concluded that long-term regular exercising may have beneficial effects on body composition and physical function in older women.

  20. Ionic liquid assisted mechanochemical preparation and electrochemical performance of graphene nanosheets/polypyrrole composite for supercapacitor

    Energy Technology Data Exchange (ETDEWEB)

    Lu, X.J.; Zhang, X.G.; Yang, S.D.; Hao, L. [Nanjing Univ. of Aeronautics and Astronautics (China). College of Material Science and Engineering

    2010-07-01

    Carbons, metal oxides, and conducting polymers are the main materials used to construct supercapacitor electrodes. As a conducting polymer, polypyrrole (PPy) is both environmentally friendly and has high capacitive characteristics. In this study, an ionic liquid (IL) assisted mechanochemical technique was used to prepare a graphene nanosheet (GNS) PPy composite. 1-butyl-3-methylimidazolium tetrachloroferrate (Bmim[FeC1{sub 4}]) was used as a bifunctional IL, as both the dispersant of the GNS and as the oxidant of the PPy. The specific capacitance of the GNS, PPy, and GNS-PPy composites were calculated. Results of the study suggested that the superior performance of the GNS-PPy composite was caused by the synergistic effect between the GNS and PPy. Use of the GNS as a supporting material provided a relatively large area on which to deposit PPy particles, which allowed more PPy to participate in faradaic redox reactions. Electrical conductivity was also improved. 2 refs., 1 fig.

  1. RuO2/MnO2 composite materials for high-performance supercapacitor electrodes

    Science.gov (United States)

    Jianming, Lei; Xiaomei, Chen

    2015-08-01

    Ruthenium oxide and manganese oxide nanomaterials were respectively prepared by a sol-gel process and hydrothermal synthesis method. The morphologies and microstructures of the composite nanomaterials were characterized by SEM and XRD. Based on the cyclic voltammetry, electrochemical impedance spectroscopy and constant current charge-discharge techniques, the performances of the electrodes were investigated. The results show that the composite of manganese oxide and ruthenium oxide is beneficial to improve the impedance characteristic. The electrode with 60% (mass ratio) manganese oxide has a high specific capacitance of 438 F/g and a lower inner resistance of 0.304 Ω using 38% (mass ratio) H2SO4 solution. The capacitance retention of RuO2/MnO2 composite electrode was 92.5% after 300 cycles.

  2. RuO2/MnO2 composite materials for high-performance supercapacitor electrodes

    International Nuclear Information System (INIS)

    Lei Jianming; Chen Xiaomei

    2015-01-01

    Ruthenium oxide and manganese oxide nanomaterials were respectively prepared by a sol–gel process and hydrothermal synthesis method. The morphologies and microstructures of the composite nanomaterials were characterized by SEM and XRD. Based on the cyclic voltammetry, electrochemical impedance spectroscopy and constant current charge–discharge techniques, the performances of the electrodes were investigated. The results show that the composite of manganese oxide and ruthenium oxide is beneficial to improve the impedance characteristic. The electrode with 60% (mass ratio) manganese oxide has a high specific capacitance of 438 F/g and a lower inner resistance of 0.304 Ω using 38% (mass ratio) H 2 SO 4 solution. The capacitance retention of RuO 2 /MnO 2 composite electrode was 92.5% after 300 cycles. (paper)

  3. Effects of roughness on interfacial performances of silica glass and non-polar polyarylacetylene resin composites

    International Nuclear Information System (INIS)

    Jiang, Z.X.; Huang, Y.D.; Liu, L.; Long, J.

    2007-01-01

    The influence of roughness on interfacial performances of silica glass/polyarylacetylene resin composites was investigated. In order to obtain different roughness, silica glass surface was abraded by different grits of abrasives and its topography was observed by scanning electron microscopy and atomic force microscopy. At the same time, the failure mechanisms of composites were analyzed by fracture morphologies and the interfacial adhesion was evaluated by shear strength test. The results indicated that shear strength of silica glass/polyarylacetylene resin composites firstly increased and then decreased with the surface roughness of silica glass increased. The best surface roughness range of silica glass was 40-60 nm. The main mechanism for the improvement of the interfacial adhesion was physical interlocking at the interface

  4. Electrochemical performance of electroactive poly(amic acid)-Cu{sup 2+} composites

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Ying [Alan G. MacDiarmid Institute, College of Chemistry, Jilin University, Changchun, 130012 (China); Li, Fangfei [State Key Lab of Superhard Materials, Jilin University, Changchun 130012 (China); Hanlon, Ashley M.; Berda, Erik B. [Department of Chemistry and Materials Science Program, University of New Hampshire, Durham, New Hampshire 03824 (United States); Liu, Xincai; Wang, Ce [Alan G. MacDiarmid Institute, College of Chemistry, Jilin University, Changchun, 130012 (China); Chao, Danming, E-mail: chaodanming@jlu.edu.cn [Alan G. MacDiarmid Institute, College of Chemistry, Jilin University, Changchun, 130012 (China)

    2017-01-15

    Graphical abstract: Electroactive poly(amic acid)-Cu{sup 2+} (EPAA-Cu) composites on the substrates have been prepared, whose electrochemical properties, including electroactivity, electrochromism and anticorrosion, reveal drastic enhancement after incorporation of Cu{sup 2+} ions. - Highlights: • The electroactive poly(amic acid)-Cu{sup 2+} (EPAA-Cu) composites were prepared. • A significant current enhancement phenomenon of EPAA-Cu/ITO electrodes was observed. • EPAA-Cu/ITO electrochromic electrodes reveals a shorter switching times. • Excellent corrosive protection for the CS was achieved by incorporating Cu{sup 2+} ions. - Abstract: Electroactive poly(amic acid)-Cu{sup 2+} (EPAA-Cu) composites on substrates were successfully prepared via nucleophilic polycondensation followed by the use of an immersing method. Analysis of the structure properties of EPAA-Cu composites was performed using scanning electron microscopy (SEM), X-ray photoelectron spectra (XPS) and Fourier-transform infrared spectra (FTIR). A significant current enhancement phenomenon of EPAA-Cu/ITO electrodes was found as evident from cyclic voltammetry (CV) measurements. In addition, Cu{sup 2+} ions were incorporated into the composites and had a positive effect on their electrochromic behaviors decreasing their switching times. The anticorrosive performance of EPAA-Cu composites coatings on the carbon steel in 3.5 wt% NaCl solution were also investigated in detail using tafel plots analysis and electrochemical impedance spectroscopy. The anticorrosive ability of these coatings significantly enhanced through the incorporation of Cu{sup 2+} ions.

  5. Modal Analysis of 27 mm Piezo Electric Plate for Small-Scale Underwater Sonar-Based Navigation

    Directory of Open Access Journals (Sweden)

    M. O. Afolayan

    2013-01-01

    Full Text Available This work presents progress towards the development of a small-scale, purely sonar-based navigation device for a robotic fish (~394 mm long. Aperture overloading of small (5 mm diameter ultrasonic transmitters does not allow them to be used effectively inside water. A test on a 27 mm diameter buzzer piezo plate shows promising performance under water at frequencies from 4.5 kHz to 80 kHz. ANSYS-based simulation was therefore used to find modal frequencies at higher frequencies so as to optimize this encouraging result. The simulation process also discovered several antiresonant frequencies such as 38.5 kHz, 54 kHz, and 57.5 kHz. All frequencies above the 8th harmonic (10,589.02 Hz are out of phase with the input load except a resonance frequency of 42.5 kHz and an antiresonance frequency of 56.5 kHz. Also, the first harmonic (1,648.73 Hz is the only frequency that gave a nodal deformation.

  6. Three-dimensional microporous polypyrrole/polysulfone composite film electrode for supercapacitance performance

    International Nuclear Information System (INIS)

    Feng, Xiaojuan; Shi, Yanlong; Jin, Shuping

    2015-01-01

    The three-dimensional microporous polypyrrole/polysulfone (PPY/PSF) composite film was fabricated via a simple polymerization method. The morphology structure and chemical composition of the composite film were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), respectively. The electrochemical properties of the composite film electrode were evaluated by cyclic voltammetry, galvanostatic charging-discharging and electrochemical impedance spectroscopy. The material exhibits excellent capacitance performance including high capacitance of 500 F g"−"1 at 0.3 A g"−"1 current density, good cycle stability in 800 continuous cycles (only 4.5% decay after 800 cycles at 0.3 A g"−"1), and low inter resistance. The good property of the PPY/PSF electrode should be attributed to its structural features, including two-layer microporous structure which facilitates the penetration of electrolytes into the inner surface, high surface area which provides more active sites. These results show that the composite film is a promising candidate for high energy electrochemical capacitors.

  7. Three-dimensional microporous polypyrrole/polysulfone composite film electrode for supercapacitance performance

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Xiaojuan, E-mail: cherry-820@163.com; Shi, Yanlong; Jin, Shuping

    2015-10-30

    The three-dimensional microporous polypyrrole/polysulfone (PPY/PSF) composite film was fabricated via a simple polymerization method. The morphology structure and chemical composition of the composite film were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), respectively. The electrochemical properties of the composite film electrode were evaluated by cyclic voltammetry, galvanostatic charging-discharging and electrochemical impedance spectroscopy. The material exhibits excellent capacitance performance including high capacitance of 500 F g{sup −1} at 0.3 A g{sup −1} current density, good cycle stability in 800 continuous cycles (only 4.5% decay after 800 cycles at 0.3 A g{sup −1}), and low inter resistance. The good property of the PPY/PSF electrode should be attributed to its structural features, including two-layer microporous structure which facilitates the penetration of electrolytes into the inner surface, high surface area which provides more active sites. These results show that the composite film is a promising candidate for high energy electrochemical capacitors.

  8. Investigation of protein adsorption performance of Ni2+-attached diatomite particles embedded in composite monolithic cryogels.

    Science.gov (United States)

    Ünlü, Nuri; Ceylan, Şeyda; Erzengin, Mahmut; Odabaşı, Mehmet

    2011-08-01

    As a low-cost natural adsorbent, diatomite (DA) (2 μm) has several advantages including high surface area, chemical reactivity, hydrophilicity and lack of toxicity. In this study, the protein adsorption performance of supermacroporous composite cryogels embedded with Ni(2+)-attached DA particles (Ni(2+)-ADAPs) was investigated. Supermacroporous poly(2-hydroxyethyl methacrylate) (PHEMA)-based monolithic composite cryogel column embedded with Ni(2+)-ADAPs was prepared by radical cryo-copolymerization of 2-hydroxyethyl methacrylate (HEMA) with N,N'-methylene-bis-acrylamide (MBAAm) as cross-linker directly in a plastic syringe for affinity purification of human serum albumin (HSA) both from aqueous solutions and human serum. The chemical composition and surface area of DA was determined by XRF and BET method, respectively. The characterization of composite cryogel was investigated by SEM. The effect of pH, and embedded Ni(2+)-ADAPs amount, initial HSA concentration, temperature and flow rate on adsorption were studied. The maximum amount of HSA adsorption from aqueous solution at pH 8.0 phosphate buffer was very high (485.15 mg/g DA). It was observed that HSA could be repeatedly adsorbed and desorbed to the embedded Ni(2+)-ADAPs in poly(2-hydroxyethyl methacrylate) composite cryogel without significant loss of adsorption capacity. The efficiency of albumin adsorption from human serum before and after albumin adsorption was also investigated with SDS-PAGE analyses. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Piezo-Hydraulic Hybrid Pump for Flight Control, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Axis Engineering Technologies proposes a revolutionary new technology that can provide performance levels, in terms of output power, bandwidth and mass, previously...

  10. Experimental study of dual fuel engine performance using variable LPG composition and engine parameters

    International Nuclear Information System (INIS)

    Elnajjar, Emad; Selim, Mohamed Y.E.; Hamdan, Mohammad O.

    2013-01-01

    Highlights: • The effect of using variable LPG is studied. • Five fuels with propane to butane % volume ratio are: 100-70-55-25-0. • 100% Propane composition shows the highest noise levels with similar performance. • At 45° BTDC injection timing 55% Propane LPG the only fuel experience knocking. • LPG fuels gave similar engine performance, with differences in levels of noise. - Abstract: The present work investigates experimentally the effect of LPG fuel with different composition and engine parameters on the performance of a dual compression engine. Five different blends of LPG fuels are used with Propane to Butane volume ratio of 100:0, 70:30, 55:45, 25:75, and 0:100. A single cylinder, naturally aspirated, four strokes, indirectly injected, water cooled modified Ricardo E6 engine, is used in this study. The study is carried out by measuring the cylinder pressure, engine load, engine speed, crank angle, and the fuel’s flow rate. The engine performance under variable LPG fuel composition, engine load, pilot fuel injection timing, compression ratio, pilot fuel mass and engine speed, are estimated by comparing the following engine parameters: the cylinder maximum pressure, the indicated mean effective pressure, the maximum rate of pressure rise, and the thermal efficiency. The experimental data indicates that the engine parameters are playing a major role on the engine’s performance. Different LPG fuel composition did not show a major effect on the engine efficiency but directly impacted the levels of generated combustion noise

  11. Board of directors’ composition and performance in French CAC 40 listed firms

    Directory of Open Access Journals (Sweden)

    Ali Ahmadi

    2017-11-01

    Full Text Available Reflecting investor expectations, most prior corporate governance research attempt to find a relationship between boards of directors’ composition and firm financial performance. Specifically, we try to examine the relationship between the boards’ size, board independence, CEO duality and gender diversity and two measurements of performance in listed companies in CAC 40, namely return on assets (ROA and return of equities (ROE. We found evidence provide that board characteristics were positively correlated to the firm’ performance. However, our results show a significant association between ROE, ROA and the board of directors’ composition. We find significant negative association between financial information and equity-based management compensation. On the other hand, the presence of independent directors on the board seems to affect, positively, the level of financial performance of CAC 40 firms. Likewise, the stewardship theory assumption, the CEO duality is very high and is significantly associated with a higher level of firm performance. The results show that there was a significant relationship between board gender diversity and firm performance from our samples CAC 40 companies. In addition, we find significant negative impact of leverage on the financial performance for CAC 40 firms.

  12. Investigation on non-equilibrium performance of composite adsorbent for resorption refrigeration

    International Nuclear Information System (INIS)

    Jiang, L.; Wang, L.W.; Zhou, Z.S.; Zhu, F.Q.; Wang, R.Z.

    2016-01-01

    Highlights: • Performance of resorption refrigeration is analyzed based on non-equilibrium reaction process. • The porous matrix improves the heat and mass performance of composite adsorbent. • The actual desorption process has the significant hysteresis phenomenon. • The highest energy efficiency of Manganese and Calcium chloride working pair is 0.272. - Abstract: The aims of this paper is to indicate that the non-equilibrium adsorption testing results is more suitable for prediction of real refrigeration performance than equilibrium data. Therefore, a test unit is constructed to test the non-equilibrium performance of different composite adsorbents. The adsorption and desorption quantity are measured and calculated by smart differential pressure transmitter. The non-equilibrium adsorption performances of working pair of Manganese chloride–ammonia, Calcium chloride–ammonia and Ammonium chloride–ammonia are investigated respectively. Results show that hysteresis phenomena happens obviously in non-equilibrium desorption process, which is related with dual variables rather than single variable. Based on the testing results, resorption refrigeration performance is analyzed, in which Manganese chloride is used as high temperature salt (HTS), and Calcium chloride, Ammonium chloride are selected as low temperature salt (LTS) for comparison. Results show that the highest COP and SCP for resorption refrigeration are about 0.272 and 45.6 W/kg, respectively. Performance of Manganese chloride–Calcium chloride and Manganese chloride–Ammonium chloride working pairs are much lower when compared with theoretical data.

  13. Investigation of properties and performance of ceramic composite components: Final report on Phases 3 and 4

    Energy Technology Data Exchange (ETDEWEB)

    Curtin, W.A.; Halverson, H.; Carter, R.H.; Miraj, N.; Reifsnider, K.L. [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States)

    1998-01-15

    The objective of the Fossil Energy Advanced Research and Technology Development (AR and TD) Materials Program is to conduct research and development on materials for longer-term fossil energy applications as well as for generic needs of various fossil fuel technologies. The research program of the Materials Response Group at Virginia Tech addresses the need for reliable and durable structural ceramic composites to perform in high temperature environments. The research effort provides an experimental and analytical basis for the transition from properties of materials to performance of actual component structures. Phases 1 and 2 of the present program focused on the development of test capabilities, initial studies of component mechanical response under various conditions and the development of a life prediction methodology. These efforts have been described in previous reports. This report summarizes the major tasks completed under Phases 3 and 4 of the project. Overall, the authors have made significant progress in a broad spectrum of tasks in this program. Their efforts have encompassed component evaluation, assessment of new SiC-based composites with improved high-temperature potential, development of oxide coating materials for SiC, and the extension and development of new models for predicting the durability of composite components under specific operating conditions for various CMC applications. Each of these areas of work is an important area for achieving the ultimate goal of usable SiC-based composites in high-temperature corrosive environments typical of fossil energy applications.

  14. Performance of PRP Associated with Porous Chitosan as a Composite Scaffold for Regenerative Medicine

    Directory of Open Access Journals (Sweden)

    Andréa Arruda Martins Shimojo

    2015-01-01

    Full Text Available This study aimed to evaluate the in vitro performance of activated platelet-rich plasma associated with porous sponges of chitosan as a composite scaffold for proliferation and osteogenic differentiation of human adipose tissue-derived mesenchymal stem cells. The sponges were prepared by controlled freezing (−20, −80, or −196°C and lyophilization of chitosan solutions (1, 2, or 3% w/v. The platelet-rich plasma was obtained from controlled centrifugation of whole blood and activated with calcium and autologous serum. The composite scaffolds were prepared by embedding the sponges with the activated platelet-rich plasma. The results showed the performance of the scaffolds was superior to that of activated platelet-rich plasma alone, in terms of delaying the release of growth factors and increased proliferation of the stem cells. The best preparation conditions of chitosan composite scaffolds that coordinated the physicochemical and mechanical properties and cell proliferation were 3% (w/v chitosan and a −20°C freezing temperature, while −196°C favored osteogenic differentiation. Although the composite scaffolds are promising for regenerative medicine, the structures require stabilization to prevent the collapse observed after five days.

  15. Preparation and supercapacitance performance of manganese oxide nanosheets/graphene/carbon nanotubes ternary composite film

    International Nuclear Information System (INIS)

    Tang, Qianqiu; Sun, Minqiang; Yu, Shuangmin; Wang, Gengchao

    2014-01-01

    Graphical abstract: - Highlights: • The MnO 2 nanosheets/graphene/MWCNT composite film with a porous sandwich structure was fabricated through a filtration-directed self-assembly. • The introduction of graphene and MWCNT restricts dense stacking of MnO 2 nanosheets. • Ternary composite film exhibits impressive electrochemical performance compared to pure MnO 2 nanosheets. - Abstract: A novel MnO 2 nanosheets/graphene nanosheets/carboxylic multi-walled carbon nanotubes (MONS/GNS/cMWCNT) ternary composite film was fabricated through a filtration-directed self-assembly method. The Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) images showed the porous sandwiched structure of MONS/GNS/cMWCNT with GNS providing a conductive substrate and cMWCNT functioning as a vertical electron pathway. The X-ray diffraction (XRD) and Raman spectra further confirmed that the introduction of GNS and cMWCNT restricted the serious aggregation of MONS, resulting in a higher specific area (691 m 2 g −1 ). As a result, the MONS/GNS/cMWCNT composite film exhibited higher specific capacitance (248 Fg −1 at 1 Ag −1 in 1 M Na 2 SO 4 ), better rate performance (66.9% capacitance retention from 0.2 to 10 Ag −1 ) and cycling stability (86.5% retention after 3000 cycles) compared with those of pure dried MnO 2 nanosheets

  16. Nanofiber reinforcement of a geopolymer matrix for improved composite materials mechanical performance

    Science.gov (United States)

    Rahman, AKM Samsur

    Geopolymers have the potential to cross the process performance gap between polymer matrix and ceramic matrix composites (CMC), enabling high temperature capable composites that are manufactured at relatively low temperatures. Unfortunately, the inherently low toughness of these geopolymers limits the performance of the resulting fiber reinforced geopolymer matrix composites. Toughness improvements in composites can be addressed through the adjustments in the fiber/matrix interfacial strength and through the improvements in the inherent toughness of the constituent materials. This study investigates the potential to improve the inherent toughness of the geopolymer matrix material through the addition of nanofillers, by considering physical dimensions, mechanical properties, reinforcing capability and interfacial bond strength effects. A process optimization study was first undertaken to develop the ability to produce consistent, neat geopolymer samples, a critical precursor to producing nano-filled geopolymer for toughness evaluation. After that, single edge notched bend beam fracture toughness and un-notched beam flexural strength were evaluated for silicon carbide, alumina and carbon nanofillers reinforced geopolymer samples treated at various temperatures in reactive and inert environments. Toughness results of silicon carbide and carbon nanofillers reinforced geopolymers suggested that with the improved baseline properties, high aspect ratio nanofillers with high interfacial bond strength are the most capable in further improving the toughness of geopolymers. Among the high aspect ratio nanofillers i.e. nanofibers, 2vol% silicon carbide whicker (SCW) showed the highest improvement in fracture toughness and flexural strength of ~164% & ~185%, respectively. After heat treatment at 650 °C, SCW reinforcement was found to be effective, with little reduction in the performance, while the performance of alumina nanofiber (ANF) reinforced geopolymer significantly

  17. Tuning Light Emission of a Pressure-Sensitive Silicon/ZnO Nanowires Heterostructure Matrix through Piezo-phototronic Effects.

    Science.gov (United States)

    Chen, Mengxiao; Pan, Caofeng; Zhang, Taiping; Li, Xiaoyi; Liang, Renrong; Wang, Zhong Lin

    2016-06-28

    Based on white light emission at silicon (Si)/ZnO hetrerojunction, a pressure-sensitive Si/ZnO nanowires heterostructure matrix light emitting diode (LED) array is developed. The light emission intensity of a single heterostructure LED is tuned by external strain: when the applied stress keeps increasing, the emission intensity first increases and then decreases with a maximum value at a compressive strain of 0.15-0.2%. This result is attributed to the piezo-phototronic effect, which can efficiently modulate the LED emission intensity by utilizing the strain-induced piezo-polarization charges. It could tune the energy band diagrams at the junction area and regulate the optoelectronic processes such as charge carriers generation, separation, recombination, and transport. This study achieves tuning silicon based devices through piezo-phototronic effect.

  18. Cyclic performance tests of Sn/MWCNT composite lithium ion battery anodes at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Tocoglu, U., E-mail: utocoglu@sakarya.edu.tr; Cevher, O.; Akbulut, H. [Sakarya University, Engineering Faculty, Department of Metallurgical and Materials Engineering, Esentepe Campus 54187 (Turkey)

    2016-04-21

    In this study tin-multi walled carbon nanotube (Sn-MWCNT) lithium ion battery anodes were produced and their electrochemical galvanostatic charge/discharge tests were conducted at various (25 °C, 35 °C, 50 °C) temperatures to determine the cyclic behaviors of anode at different temperatures. Anodes were produced via vacuum filtration and DC magnetron sputtering technique. Tin was sputtered onto buckypapers to form composite structure of anodes. SEM analysis was conducted to determine morphology of buckypapers and Sn-MWCNT composite anodes. Structural and phase analyses were conducted via X-ray diffraction and Raman Spectroscopy technique. CR2016 coin cells were assembled for electrochemical tests. Cyclic voltammetry test were carried out to determine the reversibility of reactions between anodes and reference electrode between 0.01-2.0 V potential window. Galvanostatic charge/discharge tests were performed to determine cycle performance of anodes at different temperatures.

  19. Does mechanical disturbance affect the performance and species composition of submerged macrophyte communities?

    Science.gov (United States)

    Zhang, Qian; Xu, Ying-Shou; Huang, Lin; Xue, Wei; Sun, Gong-Qi; Zhang, Ming-Xiang; Yu, Fei-Hai

    2014-05-01

    Submerged macrophyte communities are frequently subjected to disturbance of various frequency and strength. However, there is still little experimental evidence on how mechanical disturbance affects the performance and species composition of such plant communities. In a greenhouse experiment, we constructed wetland communities consisting of five co-occurring clonal submerged macrophyte species (Hydrilla verticillata, Elodea canadensis, Ceratophyllum demersum, Chara fragilis, and Myriophyllum spicatum) and subjected these communities to three mechanical disturbance regimes (no, moderate and strong disturbance). Strong mechanical disturbance greatly decreased overall biomass, number of shoot nodes and total shoot length, and increased species diversity (evenness) of the total community. It also substantially decreased the growth of the most abundant species (H. verticillata), but did not affect growth of the other four species. Our data reveal that strong disturbance can have different effects on different submerged macrophyte species and thus alters the performance and species composition of submerged macrophyte communities.

  20. Ultra High Electrical Performance of Nano Nickel Oxide and Polyaniline Composite Materials

    Directory of Open Access Journals (Sweden)

    Xiaomin Cai

    2017-07-01

    Full Text Available The cooperative effects between the PANI (polyaniline/nano-NiO (nano nickel oxide composite electrode material and redox electrolytes (potassium iodide, KI for supercapacitor applications was firstly discussed in this article, providing a novel method to prepare nano-NiO by using β-cyelodextrin (β-CD as the template agent. The experimental results revealed that the composite electrode processed a high specific capacitance (2122.75 F·g−1 at 0.1 A·g−1 in 0.05 M KI electrolyte solution, superior energy density (64.05 Wh·kg−1 at 0.2 A·g−1 in the two-electrode system and excellent cycle performance (86% capacitance retention after 1000 cycles at 1.5 A·g−1. All those ultra-high electrical performances owe to the KI active material in the electrolyte and the PANI coated nano-NiO structure.

  1. Influence of the curing cycles on the fatigue performance of unidirectional glass fiber reinforced epoxy composites

    DEFF Research Database (Denmark)

    Hüther, Jonas; Brøndsted, Povl

    2016-01-01

    During the manufacturing process of fiber reinforced polymers the curing reaction of the resin results in shrinkage of the resin and introduces internal stresses in the composites. When curing at higher temperatures in order to shorten up the processing time, higher curing stresses and thermal...... to different levels of internal stresses. The mechanical properties, static strength and fatigue life time, are measured in three different directions of the material, i.e. the fiber direction, 0°, the 30° off axis direction, and the 90° direction transverse to the fiber direction. It is experimentally...... demonstrated that the resulting residual stresses barely influences the quasi-static mechanical properties of reinforced glass-fiber composites. It is found that the fatigue performance in the 0° direction is significantly influenced by the internal stresses, whereas the fatigue performance in the off axes...

  2. Evaluation of Environmental and Hydraulic Performance of Bio-Composite Revetment Blocks

    OpenAIRE

    Thamer A.  Ahmeed; Nor A.  Alias; Abdul H.  Ghazali; Mohd. S.  Jaafar

    2006-01-01

    It is necessary to develop a concrete revetment block which can cater for environment and at the same time it will be effective in protecting river banks (stabilize the slope of banks) from scouring during flood. In the present study, the environmental and hydraulic performance of the proposed revetment block was evaluated through laboratory and field tests. The tested revetment block is called bio-composite because it is composed of concrete, plastic mesh and biological material (coconut hus...

  3. The impact of gender composition on team performance and decision-making: Evidence from the field

    OpenAIRE

    Apesteguia, Jose; Azmat, Ghazala; Iriberri, Nagore

    2010-01-01

    We investigate whether the gender composition of teams affects their economic performance. We study a large business game, played in groups of three, in which each group takes the role of a general manager. There are two parallel competitions, one involving undergraduates and the other involving MBA students. Our analysis shows that teams formed by three women are significantly outperformed by all other gender combinations, both at the undergraduate and MBA levels. Looking across the performa...

  4. Reply to “Response: Board Composition and Firm Performance: Evidence from Bangladesh - A Sceptical View”

    Directory of Open Access Journals (Sweden)

    Afzalur Rashid

    2012-09-01

    Full Text Available This paper replies to Chowdhury’s (2010 response to the paper "Board Composition and Firm Performance: Evidence from Bangladesh" (2010. It challenges the strength of the criticisms, arguing that the factors discussed in Chowdhury (2010 do not necessarily impair the outcome of the research. The authors elucidate issues raised, and in so doing, reproduce the results incorporating the commentator’s suggestions.

  5. Dynamic performance of a C/C composite finger seal in a tilting mode

    Directory of Open Access Journals (Sweden)

    Hailin ZHAO

    2017-08-01

    Full Text Available The complex operating state of aeroengines has an impact on the performance of finger seals. However, little work has been focused on the issue and the dynamic performance of finger seals is also rarely studied. Therefore, a distributed mass equivalent model considering working conditions is proposed in this paper for solving the existing problems. The effects of the fiber bundle density and the preparation direction of the fiber bundle of a C/C composite on the dynamic performance of a finger seal are investigated in rotor tilt based on the proposed model. The difference between the C/C composite finger seal performances under the rotor precession and nutation tilt cases is also investigated. The results show that the fiber bundle density and the preparation direction of the fiber bundle have an influence on the dynamic performance of the finger seal as rotor tilt is considered, and the dynamic performance of the finger seal is different in the two kinds of tilting modes. In addition, a novel method for design of finger seals is presented based on the contact pressure between finger boots and the rotor. Finger seals with good leakage rates and low wear can be acquired in this method.

  6. Biochar composite membrane for high performance pollutant management: Fabrication, structural characteristics and synergistic mechanisms.

    Science.gov (United States)

    Ghaffar, Abdul; Zhu, Xiaoying; Chen, Baoliang

    2018-02-01

    Biochar, a natural sourced carbon-rich material, has been used commonly in particle shape for carbon sequestration, soil fertility and environmental remediation. Here, we report a facile approach to fabricate freestanding biochar composite membranes for the first time. Wood biochars pyrolyzed at 300 °C and 700 °C were blended with polyvinylidene fluoride (PVdF) in three percentages (10%, 30% and 50%) to construct membranes through thermal phase inversion process. The resultant biochar composite membranes possess high mechanical strength and porous structure with uniform distribution of biochar particles throughout the membrane surface and cross-section. The membrane pure water flux was increased with B300 content (4825-5411 ± 21 L m -2 h -1 ) and B700 content (5823-6895 ± 72 L m -2 h -1 ). The membranes with B300 were more hydrophilic with higher surface free energy (58.84-60.31 mJ m -2 ) in comparison to B700 (56.32-51.91 mJ m -2 ). The biochar composite membranes indicated promising adsorption capacities (47-187 mg g -1 ) to Rhodamine B (RhB) dye. The biochar membranes also exhibited high retention (74-93%) for E. coli bacterial suspensions through filtration. After simple physical cleaning, both the adsorption and sieving capabilities of the biochar composite membranes could be effectively recovered. Synergistic mechanisms of biochar/PVdF in the composite membrane are proposed to elucidate the high performance of the membrane in pollutant management. The multifunctional biochar composite membrane not only effectively prevent the problems caused by directly using biochar particle as sorbent but also can be produced in large scale, indicating great potential for practical applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Identifying individual changes in performance with composite quality indicators while accounting for regression to the mean.

    Science.gov (United States)

    Gajewski, Byron J; Dunton, Nancy

    2013-04-01

    Almost a decade ago Morton and Torgerson indicated that perceived medical benefits could be due to "regression to the mean." Despite this caution, the regression to the mean "effects on the identification of changes in institutional performance do not seem to have been considered previously in any depth" (Jones and Spiegelhalter). As a response, Jones and Spiegelhalter provide a methodology to adjust for regression to the mean when modeling recent changes in institutional performance for one-variable quality indicators. Therefore, in our view, Jones and Spiegelhalter provide a breakthrough methodology for performance measures. At the same time, in the interests of parsimony, it is useful to aggregate individual quality indicators into a composite score. Our question is, can we develop and demonstrate a methodology that extends the "regression to the mean" literature to allow for composite quality indicators? Using a latent variable modeling approach, we extend the methodology to the composite indicator case. We demonstrate the approach on 4 indicators collected by the National Database of Nursing Quality Indicators. A simulation study further demonstrates its "proof of concept."

  8. Cardiorespiratory Fitness and Body Composition of Soccer Referees; Do These Correlate With Proper Performance?

    Science.gov (United States)

    Mazaheri, Reza; Halabchi, Farzin; Seif Barghi, Tohid; Mansournia, Mohammad Ali

    2016-03-01

    The elite-level referee is exposed to similar physical demands to those placed on a midfield soccer player. They have an important responsibility to implement the rules of the game. So, good health and performance of soccer referees have a great importance. The purpose of this study was to assess the cardiorespiratory fitness and body composition of all 78 soccer referees officiating at the Iranian Premier League and determine the correlation between these parameters and performance. In a cross-sectional study, all referees selected for the competitions were enrolled. Participants underwent exercise stress test, pulmonary function test and body composition assessment. Then the weekly scores of each referee, assessed by qualified supervisors of national federation were obtained using the FIFA standard form throughout the season (34 weeks) and registered. Among 78 participants (including 32 center and 46 side referees), mean and standard deviation of age, body mass index, percent of body fat, VO2max and performance scores were 37 ± 3.8, 23.6 ± 2.1, 20.7 ± 3.9, 59.9 ± 7.1 and 85.8 ± 0.25, respectively. No significant correlation between referees' mean score and selected parameters were found. It seems that the acquired scores of top-class referees may be influenced by multiple factors other than the laboratory findings of cardiopulmonary fitness and body composition.

  9. Electrospun polyacrylonitrile/polyurethane composite nanofibrous separator with electrochemical performance for high power lithium ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Zainab, Ghazala [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620 (China); Wang, Xianfeng, E-mail: wxf@dhu.edu.cn [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620 (China); Key Laboratory of Textile Science & Technology, Ministry of Education, College of Textiles, Donghua University, Shanghai 201620 (China); Key Laboratory of High Performance Fibers & Products, Ministry of Education, College of Textiles, Donghua University, Shanghai 201620 (China); Nanofibers Research Center, Modern Textile Institute, Donghua University, Shanghai 200051 (China); Yu, Jianyong [Key Laboratory of Textile Science & Technology, Ministry of Education, College of Textiles, Donghua University, Shanghai 201620 (China); Key Laboratory of High Performance Fibers & Products, Ministry of Education, College of Textiles, Donghua University, Shanghai 201620 (China); Nanofibers Research Center, Modern Textile Institute, Donghua University, Shanghai 200051 (China); Zhai, Yunyun; Ahmed Babar, Aijaz; Xiao, Ke [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620 (China); Ding, Bin, E-mail: binding@dhu.edu.cn [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620 (China); Key Laboratory of Textile Science & Technology, Ministry of Education, College of Textiles, Donghua University, Shanghai 201620 (China); Key Laboratory of High Performance Fibers & Products, Ministry of Education, College of Textiles, Donghua University, Shanghai 201620 (China); Nanofibers Research Center, Modern Textile Institute, Donghua University, Shanghai 200051 (China)

    2016-10-01

    Lithium ion batteries (LIBs) for high performance require separators with auspicious reliability and safety. Keeping LIBs reliability and safety in view, microporous polyacrylonitrile (PAN)/polyurethane (PU) nonwoven composite separator have been developed by electrospinning technique. The physical, electrochemical and thermal properties of the PAN/PU separator were characterized. Improved ionic conductivity up to 2.07 S cm{sup −1}, high mechanical strength (10.38 MPa) and good anodic stability up to 5.10 V are key outcomes of resultant membranes. Additionally, high thermal stability displaying only 4% dimensional change after 0.5 h long exposure to 170 °C in an oven, which could be valuable addition towards the safety of LIBs. Comparing to commercialized polypropylene based separators, resulting membranes offered improved internal short-circuit protection function, offering better rate capability and enhanced capacity retention under same observation conditions. These fascinating characteristics endow these renewable composite nonwovens as promising separators for high power LIBs battery. - Highlights: • The PAN/PU based separators were prepared by multi-needle electrospinning technique. • The electrospun separators displays good mechanical properties and thermal stability. • These separators exhibit good wettability with liquid electrolyte, high ion conductivity and internal short-circuit protection. • Nanofibrous composite nonwoven possesses stable cyclic performance which give rise to acceptable battery performances.

  10. High-performance supercapacitors using graphene/polyaniline composites deposited on kitchen sponge

    International Nuclear Information System (INIS)

    Moussa, Mahmoud; Michimore, Andrew; Majeswki, Peter; Ma, Jun; El-Kady, Maher F; Wang, Hao; Xu, Jian; Zhou, Qinqin

    2015-01-01

    We in this study used a commercial grade kitchen sponge as the scaffold where both graphene platelets (GnPs) and polyaniline (PANi) nanorods were deposited. The high electrical conductivity of GnPs (1460 S cm −1 ) enhances the pseudo-capacitive performance of PANi grown vertically on the GnPs basal planes; the interconnected pores of the sponge provide sufficient inner surface between the GnPs/PANi composite and the electrolyte, which thus facilitates ion diffusion during charge and discharge processes. When the composite electrode was used to build a supercapacitor with two-electrode configuration, it exhibited a specific capacitance of 965.3 F g −1 at a scan rate of 10 mV s −1 in 1.0 M H 2 SO 4 solution. In addition, the composite Nyquist plot showed no semicircle at high frequency corresponding to a low equivalent series resistance of 0.35 Ω. At 100 mV s −1 , the supercapacitor demonstrated an energy density of 34.5 Wh kg −1 and a power density of 12.4 kW kg −1 based on the total mass of the active materials on both electrodes. To demonstrate the performance, we built an array consisting of three cells connected in series, which lit up a red light emitting diode for five minutes. This simple method holds promise for high-performance yet low-cost electrodes for supercapacitors. (paper)

  11. The fast piezo-based frequency tuner for sc CH-cavities

    Energy Technology Data Exchange (ETDEWEB)

    Amberg, Michael [Helmholtz-Institut Mainz (HIM), Mainz (Germany); IAP University of Frankfurt, Frankfurt am Main (Germany); Aulenbacher, Kurt; Barth, Winfried [Helmholtz-Institut Mainz (HIM), Mainz (Germany); Busch, Marco; Dziuba, Florian; Podlech, Holger; Ratzinger, Ulrich [IAP University of Frankfurt, Frankfurt am Main (Germany)

    2014-07-01

    Superconducting (sc) structures have to fulfill strict mechanical requirements to assure a stable operation of a cavity. Even small mechanical disturbances caused by effects like microphonic noise, pressure fluctuations of the liquid helium bath or Lorentz force detuning can change the resonance frequency of the cavity in the range of several hundred kHz. To control the slow and fast frequency variations during operation a compact frequency tuner prototype equipped with a stepper motor and a piezo actuator has been developed at the Institute for Applied Physics (IAP) of Frankfurt University. The tuner design and the results of first mechanical tests at room temperature of the first prototype are presented.

  12. Visible-Light Modulation on Lattice Dielectric Responses of a Piezo-Phototronic Soft Material.

    Science.gov (United States)

    Huang, E-Wen; Hsu, Yu-Hsiang; Chuang, Wei-Tsung; Ko, Wen-Ching; Chang, Chung-Kai; Lee, Chih-Kung; Chang, Wen-Chi; Liao, Tzu-Kang; Thong, Hao Cheng

    2015-12-16

    In situ synchrotron X-ray diffraction is used to investigate a three-way piezo-phototronic soft material. This new system is composed of a semi-crystalline poly(vinylidene fluoride-co-trifluoroethylene) piezoelectric polymer and titanium oxide nanoparticles. Under light illumination, photon-induced piezoelectric responses are nearly two times higher at both the lattice-structure and the macroscopic level than under conditions without light illumination. A mechanistic model is proposed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. On the application of reynolds theory to thermo-piezo-viscous lubrication in oil hydraulics

    DEFF Research Database (Denmark)

    Johansen, Per; Roemer, Daniel Beck; Andersen, Torben O.

    2015-01-01

    The efficiency of fluid power motors and pumps is a subject to research, which has generated numerous publications during the last three decades. The main incentives for this research are optimization of reliability and efficiency through the study of loss and wear mechanisms, which are very....... In this paper the derivation of Reynolds equation from the continuum assumption is reviewed and it is shown that the validity of Reynolds theory based pressure field solutions in oil hydraulic thermo-piezo-viscous lubrication models are subject to maximum bounds on the pressure and temperature field gradients...

  14. 5-year clinical performance of resin composite versus resin modified glass ionomer restorative system in non-carious cervical lesions

    DEFF Research Database (Denmark)

    Franco, Eduardo Batista; Benetti, Ana Raquel; Ishikiriama, Sérgio Kiyoshi

    2006-01-01

    To comparatively assess the 5-year clinical performance of a 1-bottle adhesive and resin composite system with a resin-modified glass ionomer restorative in non-carious cervical lesions.......To comparatively assess the 5-year clinical performance of a 1-bottle adhesive and resin composite system with a resin-modified glass ionomer restorative in non-carious cervical lesions....

  15. Performance of direct methanol fuel cell with a palladium–silica nanofibre/Nafion composite membrane

    International Nuclear Information System (INIS)

    Thiam, H.S.; Daud, W.R.W.; Kamarudin, S.K.; Mohamad, A.B.; Kadhum, A.A.H.; Loh, K.S.; Majlan, E.H.

    2013-01-01

    Highlights: • This study introduces Pd–SiO 2 Carbon Nano Fibre as an additive to Nafion membrane. • It investigates the effects of membrane annealing temperature and casting solvent. • Results show that Pd–SiO 2 fibre/Nafion performs lower methanol permeability. • This could effectively reduces methanol crossover in direct methanol fuel cell. - Abstract: Palladium–silica nanofibres (Pd–SiO 2 fibre) were adopted as an additive to Nafion recast membranes in order to reduce methanol crossover and improve the cell performance. The performance of a membrane electrode assembly (MEA) with fabricated composite membrane was evaluated through a passive air-breathing single cell direct methanol fuel cell (DMFC). The limiting crossover current density was measured to determine the methanol permeation in the DMFC. The effects of membrane annealing temperature and casting solvent of composite membrane on the cell performance were investigated and are discussed here. Compared to recast Nafion with the same thickness (150 μm), the Pd–SiO 2 fibre/Nafion composite membrane exhibited higher performance and lower methanol permeability. A maximum power density of 10.4 mW cm −2 was obtained with a 2 M methanol feed, outperforming the much thicker commercial Nafion 117 with a power density of 7.95 mW cm −2 under the same operating conditions. The experimental results showed that the Pd–SiO 2 fibre as inorganic fillers for Nafion could effectively reduce methanol crossover and improve the membrane performance in DMFC applications

  16. Simple, low-noise piezo driver with feed-forward for broad tuning of external cavity diode lasers.

    Science.gov (United States)

    Doret, S Charles

    2018-02-01

    We present an inexpensive, low-noise (piezo driver suitable for frequency tuning of external-cavity diode lasers. This simple driver improves upon many commercially available drivers by incorporating circuitry to produce a "feed-forward" signal appropriate for making simultaneous adjustments to the piezo voltage and laser current, enabling dramatic improvements in a mode-hop-free laser frequency tuning range. We present the theory behind our driver's operation, characterize its output noise, and demonstrate its use in absorption spectroscopy on the rubidium D 1 line.

  17. In situ ZnO nanowire growth to promote the PVDF piezo phase and the ZnO-PVDF hybrid self-rectified nanogenerator as a touch sensor.

    Science.gov (United States)

    Li, Zetang; Zhang, Xu; Li, Guanghe

    2014-03-28

    A PVDF-ZnO nanowires (NWs) hybrid generator (PZHG) was designed. A simple, cost effective method to produce the PVDF β phase by nano force is introduced. With the ZnO NWs growing, the in situ nano extension force promotes the phase change. A theoretical analysis of the ZnO NWs acting as a self-rectifier of the nano generator is established. The ZnO NWs acted as a self-adjustment diode to control the current output of the PZHG by piezo-electric and semi-conductive effects. Based on the self-controllability of the piezoelectric output, three kinds of finger touching are distinguished by the output performances of the PZHG, which is applicable to an LCD touch pad.

  18. Basic role of the fiber/matrix interface on the fatigue performance of unidirectional fiberglass-reinforced composites

    International Nuclear Information System (INIS)

    Shih, C.

    1985-01-01

    The goal of this study was that of determining the fiber/matrix interface in affecting the static bending and flexural fatigue performance of oriented fiber composites, and of evaluating the performance of silicon phthalocyanine coupling agents. Untreated, commercial silane treated, and silicon phthalocyanine agent treated fiberglass composites, as well as boiling-water degraded composites, were used to get different fiber/matrix interface conditions. The dry flexural strength of all composites was about the same. The flexural strength and the fractography of N-(2-aminoethyl)-3-aminopropyl-trimethoxysilane treated composites essentially remained the same after the hydrothermal treatment. Silicon phthalocyanine agent treated composites had a marginally high wet flexural strength retention as compared with that of the composites without coupling agent. When the interface degraded, the failure modes in a four-point bending (flexural) test changed from tensile flexural failure to compressive flexural failure, then to the shear failure mode

  19. Nanostructure Sn-Co-C composite lithium ion battery electrode with unique stability and high electrochemical performance

    International Nuclear Information System (INIS)

    Li Mengyuan; Liu Chunling; Shi Meirong; Dong Wensheng

    2011-01-01

    Nanostructure Sn-Co-C composites with different compositions are synthesized by a simple solution polymerization using inexpensive raw materials followed by pyrolysis in nitrogen atmosphere. The nanostructure Sn-Co-C composites are characterized using various analytic techniques. The results show that the electrochemical performances of the composites are strongly dependent on their structure and composition. Among these composites the Sn-Co-C-1 with a weight composition of Sn 0.31 Co 0.09 C 0.6 exhibits high reversible capacity and excellent cycleability when used as an anode for rechargeable lithium ion batteries. This composite is composed of SnCo 2 , SnCo, Sn and amorphous carbon, and the nanoparticles of SnCo 2 , SnCo and Sn are uniformly dispersed into the amorphous carbon matrix, the average diameter of these metal nanoparticles is 8.44 nm.

  20. Micromechanics and Piezo Enhancements of HyperSizer

    Science.gov (United States)

    Arnold, Steven M.; Bednarcyk, Brett A.; Yarrington, Phillip; Collier, Craig S.

    2006-01-01

    The commercial HyperSizer aerospace-composite-material-structure-sizing software has been enhanced by incorporating capabilities for representing coupled thermal, piezoelectric, and piezomagnetic effects on the levels of plies, laminates, and stiffened panels. This enhancement is based on a formulation similar to that of the pre-existing HyperSizer capability for representing thermal effects. As a result of this enhancement, the electric and/or magnetic response of a material or structure to a mechanical or thermal load, or its mechanical response to an applied electric or magnetic field can be predicted. In another major enhancement, a capability for representing micromechanical effects has been added by establishment of a linkage between HyperSizer and Glenn Research Center s Micromechanics Analysis Code With Generalized Method of Cells (MAC/GMC) computer program, which was described in several prior NASA Tech Briefs articles. The linkage enables Hyper- Sizer to localize to the fiber and matrix level rather than only to the ply level, making it possible to predict local failures and to predict properties of plies from those of the component fiber and matrix materials. Advanced graphical user interfaces and database structures have been developed to support the new HyperSizer micromechanics capabilities.

  1. Photocatalytic performance of graphene/TiO_2-Ag composites on amaranth dye degradation

    International Nuclear Information System (INIS)

    Roşu, Marcela-Corina; Socaci, Crina; Floare-Avram, Veronica; Borodi, Gheorghe; Pogăcean, Florina; Coroş, Maria; Măgeruşan, Lidia; Pruneanu, Stela

    2016-01-01

    Ternary nanocomposites containing TiO_2, silver and graphene with different reduction levels were prepared and used as photocatalysts for amaranth azo dye degradation, under UV and natural light exposure. The obtained materials were characterized by TEM, XRD, FTIR and UV-Vis spectroscopy, confirming the successful formation of the nanocomposites. HPLC analysis along with UV-Vis spectroscopy were employed to quantify the concentration of non-degraded dye in solution. The graphene/TiO_2-Ag nanocomposites proved to have remarkable photocatalytic activities for amaranth degradation under UV and solar irradiation (85.3–98% of dye has disappeared in the first 2 h). Also, significant removal efficiencies (between 40.5 and 71.8%) of photocatalysts, in day light conditions, were demonstrated. The best result for amaranth dye degradation was obtained with the reduced graphene/TiO_2-Ag catalyst (up to 99.9%). Based on the degradation products analysis, a photodegradation pathway of amaranth dye was also proposed. - Highlights: • Graphene/TiO_2-Ag composites were prepared by a combined chemical-thermal method. • The composites showed improved light-absorption characteristics. • A significant degradation performance of amaranth was obtained with these composites under UV and natural light exposure. • Graphene/TiO_2-Ag composites offer a high potential for various photocatalytic applications in pollutant removal processes.

  2. Synthesis and Photocatalytic Performance of RGO/ZnO Nanorod Composites

    Directory of Open Access Journals (Sweden)

    LU Jia

    2016-12-01

    Full Text Available ZnO nanorods and RGO/ZnO nanorods composites were prepared by hydrothermal method. The influence of RGO content on the photocatalytic activity of RGO/ZnO nanorods composites was studied. ZnO nanorods and RGO/ZnO nanocomposites were characterized by X-ray diffraction (XRD, field emission electron microscopy (FESEM, X-ray photoelectron spectroscopy (XPS and diffuse reflectance UV-visible absorption spectroscopy techniques. The results show that RGO/ZnO samples are synthesized successfully. With different additions of GO, the RGO/ZnO samples obtained exhibit different absorption characteristics in visible light region. The photocatalytic results of using methyl orange (MO as the simulated pollutant show that RGO/ZnO nanorods composites exhibit high degradation efficiency under UV-Vis light illumination. The highest photocatalytic performance is obtained for RGO/ZnO composites when the mass ratio of RGO to ZnO is 3%. MO is almost completely degraded in 120min. RGO/ZnO also shows the visible-light-driven photocatalytic activity under visible light illumination (λ>400nm, and the maximum MO degradation efficiency in 180min can reach 26.2%, meanwhile, RGO/ZnO samples exhibit good photostability.

  3. Research on optimizing components of microfine high-performance composite cementitious materials

    International Nuclear Information System (INIS)

    Hu Shuguang; Guan Xuemao; Ding Qingjun

    2002-01-01

    The relationship between material components and mechanical properties was studied in terms of composite material principles and orthogonal experimental design. Moreover, the microstructure of microfine high-performance composite cementitious material (MHPCC) paste was investigated by means of scanning electron microscopy (SEM) methods. The results showed that the composite material consisting of blast furnace slag (BFS), gypsum (G 2 ) and expansive agent (EA) could obviously improve the strength of the cementitious material containing 40% fly ash (FA). Although microfine cement (MC) was merely 45% percent of the MHPCC, the compressive strength of MHPCC paste was higher than that of neat MC paste. BFS played an important role in MHPCC. The optimum-added quantity of BFS was 15%. The needle-shaped ettringite obtained from the EA reacting with Ca(OH) 2 forms a three-dimensional network structure, which not only improved the early strength of MHPCC paste but also increased its late strength. The reason was that the network structure, which was similar to a fiber-reinforced composite, was formed in the late period of hydration with the progress of hydration and the deposition of hydration products into the network structure

  4. Core-Shell Composite Fibers for High-Performance Flexible Supercapacitor Electrodes.

    Science.gov (United States)

    Lu, Xiaoyan; Shen, Chen; Zhang, Zeyang; Barrios, Elizabeth; Zhai, Lei

    2018-01-31

    Core-shell nanofibers containing poly(acrylic acid) (PAA) and manganese oxide nanoparticles as the core and polypyrrole (PPy) as the shell were fabricated through electrospinning the solution of PAA and manganese ions (PAA/Mn 2+ ). The obtained nanofibers were stabilized by Fe 3+ through the interaction between Fe 3+ ions and carboxylate groups. Subsequent oxidation of Mn 2+ by KMnO 4 produced uniform manganese dioxide (MnO 2 ) nanoparticles in the fibers. A PPy shell was created on the fibers by immersing the fibers in a pyrrole solution where the Fe 3+ ions in the fiber polymerized the pyrrole on the fiber surfaces. In the MnO 2 @PAA/PPy core-shell composite fibers, MnO 2 nanoparticles function as high-capacity materials, while the PPy shell prevents the loss of MnO 2 during the charge/discharge process. Such a unique structure makes the composite fibers efficient electrode materials for supercapacitors. The gravimetric specific capacity of the MnO 2 @PAA/PPy core-shell composite fibers was 564 F/g based on cyclic voltammetry curves at 10 mV/s and 580 F/g based on galvanostatic charge/discharge studies at 5 A/g. The MnO 2 @PAA/PPy core-shell composite fibers also present stable cycling performance with 100% capacitance retention after 5000 cycles.

  5. Text Comprehension Mediates Morphological Awareness, Syntactic Processing, and Working Memory in Predicting Chinese Written Composition Performance

    Science.gov (United States)

    Guan, Connie Qun; Ye, Feifei; Wagner, Richard K.; Meng, Wanjin; Leong, Che Kan

    2014-01-01

    The goal of the present study was to test opposing views about four issues concerning predictors of individual differences in Chinese written composition: (a) Whether morphological awareness, syntactic processing, and working memory represent distinct and measureable constructs in Chinese or are just manifestations of general language ability; (b) whether they are important predictors of Chinese written composition, and if so, the relative magnitudes and independence of their predictive relations; (c) whether observed predictive relations are mediated by text comprehension; and (d) whether these relations vary or are developmentally invariant across three years of writing development. Based on analyses of the performance of students in grades 4 (n = 246), 5 (n = 242) and 6 (n = 261), the results supported morphological awareness, syntactic processing, and working memory as distinct yet correlated abilities that made independent contributions to predicting Chinese written composition, with working memory as the strongest predictor. However, predictive relations were mediated by text comprehension. The final model accounted for approximately 75 percent of the variance in Chinese written composition. The results were largely developmentally invariant across the three grades from which participants were drawn. PMID:25530630

  6. EXPERIMENTAL RESEARCH OF THE THREE-DIMENSIONAL PERFORMANCE OF COMPOSITE STEEL AND CONCRETE STRUCTURES

    Directory of Open Access Journals (Sweden)

    Zamaliev Farit Sakhapovich

    2012-12-01

    steel-concrete slabs limits their use in the construction of residential housing. This article describes the composition, geometry, reinforcement, and anchors to enable the use of concrete slabs and steel beams. The article contains photographs that illustrate the load distribution model. Methods of testing of fiber strains of concrete slabs and steel profiles, deflections of beams, shear stresses in the layers of the "steel-to-concrete" contact area that may involve slab cracking are analyzed. Dynamics of fiber deformations of concrete slabs, steel beams, and layers of the "steel-to-concrete" contact areas, deflection development patterns, initial cracking and crack development to destruction are analyzed. The author also describes the fracture behavior of the floor model. Results of experimental studies of the three-dimensional overlapping of structural elements are compared to the test data of individual composite beams. Peculiarities of the stress-strain state of composite steel and concrete slabs, graphs of strains and stresses developing in sections of middle and external steel-and-concrete beams, deflection graphs depending on the loading intensity are provided. The findings of the experimental studies of the three-dimensional performance of composite steel-and-concrete slabs are provided, as well.

  7. Photocatalytic performance of graphene/TiO{sub 2}-Ag composites on amaranth dye degradation

    Energy Technology Data Exchange (ETDEWEB)

    Roşu, Marcela-Corina, E-mail: marcela.rosu@itim-cj.ro; Socaci, Crina; Floare-Avram, Veronica; Borodi, Gheorghe; Pogăcean, Florina; Coroş, Maria; Măgeruşan, Lidia; Pruneanu, Stela

    2016-08-15

    Ternary nanocomposites containing TiO{sub 2}, silver and graphene with different reduction levels were prepared and used as photocatalysts for amaranth azo dye degradation, under UV and natural light exposure. The obtained materials were characterized by TEM, XRD, FTIR and UV-Vis spectroscopy, confirming the successful formation of the nanocomposites. HPLC analysis along with UV-Vis spectroscopy were employed to quantify the concentration of non-degraded dye in solution. The graphene/TiO{sub 2}-Ag nanocomposites proved to have remarkable photocatalytic activities for amaranth degradation under UV and solar irradiation (85.3–98% of dye has disappeared in the first 2 h). Also, significant removal efficiencies (between 40.5 and 71.8%) of photocatalysts, in day light conditions, were demonstrated. The best result for amaranth dye degradation was obtained with the reduced graphene/TiO{sub 2}-Ag catalyst (up to 99.9%). Based on the degradation products analysis, a photodegradation pathway of amaranth dye was also proposed. - Highlights: • Graphene/TiO{sub 2}-Ag composites were prepared by a combined chemical-thermal method. • The composites showed improved light-absorption characteristics. • A significant degradation performance of amaranth was obtained with these composites under UV and natural light exposure. • Graphene/TiO{sub 2}-Ag composites offer a high potential for various photocatalytic applications in pollutant removal processes.

  8. Zirconium oxide nanotube-Nafion composite as high performance membrane for all vanadium redox flow battery

    Science.gov (United States)

    Aziz, Md. Abdul; Shanmugam, Sangaraju

    2017-01-01

    A high-performance composite membrane for vanadium redox flow battery (VRB) consisting of ZrO2 nanotubes (ZrNT) and perfluorosulfonic acid (Nafion) was fabricated. The VRB operated with a composite (Nafion-ZrNT) membrane showed the improved ion-selectivity (ratio of proton conductivity to permeability), low self-discharge rate, high discharge capacity and high energy efficiency in comparison with a pristine commercial Nafion-117 membrane. The incorporation of zirconium oxide nanotubes in the Nafion matrix exhibits high proton conductivity (95.2 mS cm-1) and high oxidative stability (99.9%). The Nafion-ZrNT composite membrane exhibited low vanadium ion permeability (3.2 × 10-9 cm2 min-1) and superior ion selectivity (2.95 × 107 S min cm-3). The VRB constructed with a Nafion-ZrNT composite membrane has lower self-discharge rate maintaining an open-circuit voltage of 1.3 V for 330 h relative to a pristine Nafion membrane (29 h). The discharge capacity of Nafion-ZrNT membrane (987 mAh) was 3.5-times higher than Nafion-117 membrane (280 mAh) after 100 charge-discharge cycles. These superior properties resulted in higher coulombic and voltage efficiencies with Nafion-ZrNT membranes compared to VRB with Nafion-117 membrane at a 40 mA cm-2 current density.

  9. Body composition and military performance--many things to many people.

    Science.gov (United States)

    Friedl, Karl E

    2012-07-01

    Soldiers are expected to maintain the highest possible level of physical readiness because they must be ready to mobilize and perform their duties anywhere in the world at any time. The objective of Army body composition standards is to motivate physical training and good nutrition habits to ensure a high state of readiness. Establishment of enforceable and rational standards to support this objective has been challenging even at extremes of body size. Morbidly obese individuals are clearly not suited to military service, but very large muscular individuals may be superbly qualified for soldier performance demands. For this reason, large individuals are measured for body fat using a waist circumference-based equation (female soldiers are also measured for hip circumference). The main challenge comes in setting appropriate fat standards to support the full range of Army requirements. Military appearance ideals dictate the most stringent body fat standards, whereas health risk thresholds anchor the most liberal standards, and physical performance associations fall on a spectrum between these 2 poles. Standards should not exclude or penalize specialized performance capabilities such as endurance running or power lifting across a spectrum of body sizes and fat. The full integration of women into the military further complicates the issue because of sexually dimorphic characteristics that make gender-appropriate standards essential and where inappropriately stringent standards can compromise both health and performance of this segment of the force. Other associations with body composition such as stress effects on intraabdominal fat distribution patterns and metabolic implications of a fat reserve for survival in extreme environments are also relevant considerations. This is a review of the science that underpins the U.S. Army body composition standards.

  10. The role of film composition and nanostructuration on the polyphenol sensor performance

    Directory of Open Access Journals (Sweden)

    Cibely Silva Martin

    2016-12-01

    Full Text Available The recent advances in the supramolecular control in nanostructured films have improved the performance of organic-based devices. However, the effect of different supramolecular arrangement on the sensor or biosensor performance is poorly studied yet. In this paper, we show the role of the composition and nanostructuration of the films on the impedance and voltammetric-based sensor performance to catechol detection. The films here studied were composed by a perylene derivative (PTCD-NH2 and a metallic phthalocyanine (FePc, using Langmuir-Blodgett (LB and physical vapor deposition (PVD techniques. The deposition technique and intrinsic properties of compounds showed influence on electrical and electrocatalytic responses. The PVD PTCD-NH2 shows the best sensor performance to the detection of catechol. Quantification of catechol contents in mate tea samples was also evaluated, and the results showed good agreement compared with Folin-Ciocalteu standard method for polyphenol detection.

  11. Controlling Buffeting Loads by Rudder and Piezo-Actuation

    Science.gov (United States)

    Moses, Robert W.; Pototzky, Anthony S.; Henderson, Douglas A.; Galea, Stephen C.; Manokaran, Donald S.; Zimcik, David G.; Wickramasinghe, Viresh; Pitt, Dale M.; Gamble, Michael A.

    2005-01-01

    High performance aircraft, especially those with twin vertical tails, encounter unsteady buffet loads when flying at high angles of attack. These stochastic loads result in significant stresses, which may cause fatigue damage leading to restricted capabilities and availability of the aircraft. An international collaborative research activity among Australia, Canada and the United States, conducted under the auspices of The Technical Cooperation Program (TTCP) contributed resources toward a program that coalesced a broad range of technical knowledge and expertise into a single investigation to demonstrate the enhanced performance and capability of the advanced active Buffet Load Alleviation ( ) control system in preparation for a flight test demonstration. The research team investigated the use of active structural control to alleviate the damaging structural response to these loads by applying advanced directional piezoelectric actuators, the aircraft rudder, switch mode amplifiers, and advanced control strategies on an F/A-18 aircraft empennage. Some results of the full-scale investigation are presented herein.

  12. Performance evaluation on solar still integrated with nano-composite phase change materials

    International Nuclear Information System (INIS)

    Rajasekhar, G.; Eswaramoorthy, M.

    2015-01-01

    This paper communicates the performance evaluation of single slope solar still integrated with nano-composite phase change materials and compare with the experimental results of with and without phase change materials. A solar still with 1 m"2 surface area is developed with non-selective coating of absorber sheet with the provision of thermal energy storage materials. The solar still is tested on typical days with and without thermal energy storage materials. It is found that from the experimental studies that nano-materials (Al_2O_3) dispersed in paraffin wax is giving better cumulative yield of distillate than paraffin wax alone and without paraffin wax thermal storage. The daily efficiency of the solar still is computed for solar still with nano-composite phase change materials is 45% and solar still paraffin wax alone thermal storage is 40% and solar still without any thermal storage is 38%. It is concluded from the experimental studies; solar still integrated with nano-composite phase change materials gives better performance than with and without phase change material alone. (authors)

  13. Improved electrochemical performance of polyindole/carbon nanotubes composite as electrode material for supercapacitors

    Science.gov (United States)

    Cai, Zhi-Jiang; Zhang, Qin; Song, Xian-You

    2016-09-01

    Polyindole/carbon nanotubes (PIN/CNTs) composite was prepared by an in-situ chemical oxidative polymerization of indole monomer with CNTs using ammonium persulfate as oxidant. The obtained composite material was characterized by SEM, TEM, FT-IR, Raman spectroscopy, XPS, XRD and BET surface areas measurements. It was found that the CNTs were incorporated into the PIN matrix and nanoporous structure was formed. Spectroscopy results showed that interfacial interaction bonds might be formed between the polyindole chains and CNTs during the in-situ polymerization. PIN/CNTs composite was evaluated by electrochemical impedance spectroscopy, cyclic voltammetry and charge/discharge tests to determine electrode performances in relation to supercapacitors properties in both aqueous and non-aqueous system. A maximum specific capacitance and specific volumetric capacitance of 555.6 F/g and 222.2 F/cm3 can be achieved at 0.5 A/g in non-aqueous system. It also displayed good rate performance and cycling stability. The specific capacitance retention is over 60% at 10 A/g and 91.3% after 5000 cycles at 2 A/g, respectively. These characteristics point to its promising applications in the electrode material for supercapacitors.

  14. Progress in Jc and magnetic field performance of Bi-2223/Ag composite tapes

    International Nuclear Information System (INIS)

    Savvides, N.; Katsaros, A.; Reilly, D.; Thorley, A.; Herrmann, J.

    1998-01-01

    Full text: The application of high-temperature superconductors to electric power systems is actively pursued by several commercial teams around the world. A promising candidate is the Bi-2223/Ag composite superconductor. For large scale commercial applications the conductor must meet certain engineering specifications including high current capacity in the presence of a self-generated magnetic field ranging from a few hundred mT in transmission cables to 1-2 T in transformers and current limiters, and to much higher fields in the case of superconducting coils for energy storage and magnets. In the last two years, a commercial consortium consisting of Metal Manufactures Ltd, University of Wollongong and CSIRO has focused on the development of Bi-2223/Ag composite tape suitable for use in electric power applications. The powder-in-tube process is used to produce conventional single filament and multifilament tapes and twisted conductors. An appropriate measure of 'process capability' is routine running of the process and evaluation of tape performance. In this paper we report on the electrical properties of Bi-2223/Ag composite tapes produced as part of the long-length product development. The transport critical current density of tapes is measured in magnetic fields up to 9 T (H parallel and H perpendicular tape-plane) and as a function of temperature (4 - 80 K). Transport ac losses are determined at 77 K and 60 Hz, and the bend strain performance is determined at 77 K for strains up to 1.5 %

  15. Three-dimensional N-doped graphene/polyaniline composite foam for high performance supercapacitors

    Science.gov (United States)

    Zhu, Jun; Kong, Lirong; Shen, Xiaoping; Chen, Quanrun; Ji, Zhenyuan; Wang, Jiheng; Xu, Keqiang; Zhu, Guoxing

    2018-01-01

    Three-dimensional (3D) graphene aerogel and its composite with interconnected pores have aroused continuous interests in energy storage field owning to its large surface area and hierarchical pore structure. Herein, we reported the preparation of 3D nitrogen-doped graphene/polyaniline (N-GE/PANI) composite foam for supercapacitive material with greatly improved electrochemical performance. The 3D porous structure can allow the penetration and diffusion of electrolyte, the incorporation of nitrogen doping can enhance the wettability of the active material and the number of active sites with electrolyte, and both the N-GE and PANI can ensure the high electrical conductivity of total electrode. Moreover, the synergistic effect between N-GE and PANI materials also play an important role on the electrochemical performance of electrode. Therefore, the as-prepared composite foam could deliver a high specific capacitance of 528 F g-1 at 0.1 A g-1 and a high cyclic stability with 95.9% capacitance retention after 5000 charge-discharge cycles. This study provides a new idea on improving the energy storage capacity of supercapacitors by using 3D graphene-based psedocapacitive electrode materials.

  16. Aqueous preparation of polyethylene glycol/sulfonated graphene phase change composite with enhanced thermal performance

    International Nuclear Information System (INIS)

    Li, Hairong; Jiang, Ming; Li, Qi; Li, Denian; Chen, Zongyi; Hu, Waping; Huang, Jing; Xu, Xizhe; Dong, Lijie; Xie, Haian; Xiong, Chuanxi

    2013-01-01

    Highlights: • We report an aqueous preparation technique of PEG/graphene phase change composite. • Hydrophilic sulfonated graphene (SG) nanosheets were synthesized. • Large increase in thermal conductivity is attained at low SG loading. • High latent heat is retained due to the low filler loading. • Affinity between SG and PEG contributes to the enhanced thermal performance. - Abstract: A polyethylene glycol (PEG)/sulfonated graphene (SG) phase change composite with enhanced thermal performance was prepared by solution processing in aqueous medium. It is remarkable that the addition of only 4 wt.% of SG to PEG could lead to a four times higher increase in thermal conductivity and a slight decrease in the phase change enthalpy, which is attributed to the formation of efficient thermal conductive network within the PEG matrix relevant to the excellent thermal property and unique 2-dimensional morphology of graphene as well as strong interface affinity between PEG matrix and SG nanosheets. The aqueous preparation technique is expected to pioneer a new way to prepare environment friendly organic phase change materials, and the production of PEG/SG composites is potentially scalable due to the facile fabricating process

  17. Study of geometry angles forming a coaxial nozzle to performance of laser fusion powder composition

    Directory of Open Access Journals (Sweden)

    Павло Васильович Кондрашев

    2017-06-01

    Full Text Available The main purpose of scientific and experimental research, as reflected in this work is the search for solutions and approaches aimed at improving process performance laser alloying powder composition focused laser radiation. Priori information analysis showed the complexity of the process of laser powder fusion tracks from the physical point of view with a lot of technological impacts. Therefore, in this paper we used the method of experimental design, which will allow a more accurate experimental results compared with other methods of research. Based on the experimental screening were identified most significant technological factors influence. These are: powder mass flow, the geometric configuration of the delivery means of powder composition in the area of laser processing, the speed of movement of the substrate. To study the process performance laser alloying powder compositions were applied methods of mathematical statistics, namely, was elected symmetric quasi-D-optimal plan Pisochynskoho for 3 technological factors influence that has good statistical properties and sold regression equation of second order. As a result of the measures was received mathematical model of laser powder fusion focused laser radiation in a second order polynomial. The technique demonstrated the productivity of the process of laser powder fusion focused laser radiation, obtained by using a mathematical model of the process.

  18. Enhancement in ballistic performance of composite hard armor through carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Jason Gibson

    2013-12-01

    Full Text Available The use of carbon nanotubes in composite hard armor is discussed in this study. The processing techniques to make various armor composite panels consisting of Kevlar®29 woven fabric in an epoxy matrix and the subsequent V50 test results for both 44 caliber soft-point rounds and 30 caliber FSP (fragment simulated projectile threats are presented. A 6.5% improvement in the V50 test results was found for a combination of 1.65 wt% loading of carbon nanotubes and 1.65 wt% loading of milled fibers. The failure mechanism of carbon nanotubes during the ballistic event is discussed through scanning electron microscope images of the panels after the failure. Raman Spectroscopy was also utilized to evaluate the residual strain in the Kevlar®29 fibers post shoot. The Raman Spectroscopy shows a Raman shift of 25 cm−1 for the Kevlar®29 fiber utilized in the composite panel that had an enhancement in the V50 performance by using milled fiber and multi-walled carbon nanotubes. Evaluating both scenarios where an improvement was made and other panels without any improvement allows for understanding of how loading levels and synergistic effects between carbon nanotubes and milled fibers can further enhance ballistic performance.

  19. Performance of high amylose starch-composited gelatin films influenced by gelatinization and concentration.

    Science.gov (United States)

    Wang, Wenhang; Wang, Kun; Xiao, Jingdong; Liu, Yaowei; Zhao, Yana; Liu, Anjun

    2017-01-01

    In order to study the impact of starch in film performance, high amylose corn starch was composited in gelatin films under different gelatinization conditions and, in high and low concentrations (10 and 50wt.%). It was found that hot water gelatinized starch (Gel-Shw) increased film mechanical strength and was dependent upon the starch concentration. The addition of an alkali component to the starch significantly enhanced the swelling of the starch granules and expedited the gelatinization process. Incorporation of starch, especially the alkalized starch (Sha), into the gelatin films decreased film solubility which improved its water resistance and water vapor permeability (WVP). Multiple techniques (DSC, TGA, FT-IR, and XRD) were used to characterize the process and results, including the crosslinking of the dissolved starch molecules and the particles formed from gelatinized starch during retrogradation process, which played an important role in improving the thermal stability of the composited gelatin films. Overall, the starch-gelatin composition provides a potential approach to improve gelatin film performance and benefit its applications in the food industry. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Compressed multiwall carbon nanotube composite electrodes provide enhanced electroanalytical performance for determination of serotonin

    International Nuclear Information System (INIS)

    Fagan-Murphy, Aidan; Patel, Bhavik Anil

    2014-01-01

    Serotonin (5-HT) is an important neurochemical that is present in high concentrations within the intestinal tract. Carbon fibre and boron-doped diamond based electrodes have been widely used to date for monitoring 5-HT, however these electrodes are prone to fouling and are difficult to fabricate in certain sizes and geometries. Carbon nanotubes have shown potential as a suitable material for electroanalytical monitoring of 5-HT but can be difficult to manipulate into a suitable form. The fabrication of composite electrodes is an approach that can shape conductive materials into practical electrode geometries suitable for biological environments. This work investigated how compression of multiwall carbon nanotubes (MWCNTs) epoxy composite electrodes can influence their electroanalytical performance. Highly compressed composite electrodes displayed significant improvements in their electrochemical properties along with decreased internal and charge transfer resistance, reproducible behaviour and improved batch to batch variability when compared to non-compressed composite electrodes. Compression of MWCNT epoxy composite electrodes resulted in an increased current response for potassium ferricyanide, ruthenium hexaammine and dopamine, by preferentially removing the epoxy during compression and increasing the electrochemical active surface of the final electrode. For the detection of serotonin, compressed electrodes have a lower limit of detection and improved sensitivity compared to non-compressed electrodes. Fouling studies were carried out in 10 μM serotonin where the MWCNT compressed electrodes were shown to be less prone to fouling than non-compressed electrodes. This work indicates that the compression of MWCNT carbon-epoxy can result in a highly conductive material that can be moulded to various geometries, thus providing scope for electroanalytical measurements and the production of a wide range of analytical devices for a variety of systems

  1. Constitutive modeling of SMA SMP multifunctional high performance smart adaptive shape memory composite

    International Nuclear Information System (INIS)

    Jarali, Chetan S; Raja, S; Upadhya, A R

    2010-01-01

    Materials design involving the thermomechanical constitutive modeling of shape memory alloy (SMA) and shape memory polymer (SMP) composites is a key topic in the development of smart adaptive shape memory composites (SASMC). In this work, a constitutive model for SASMC is developed. First, a one-dimensional SMA model, which can simulate the pseudoelastic (PE) and shape memory effects (SME) is presented. Subsequently, a one-dimensional SMP model able to reproduce the SME is addressed. Both SMA and SMP models are based on a single internal state variable, namely the martensite fraction and the frozen fraction, which can be expressed as a function of temperature. A consistent form of the analytical solution for the SMP model is obtained using the fourth-order Runge–Kutta method. Finally, the SASMC constitutive model is proposed, following two analytical homogenization approaches. One approach is based on an equivalent inclusion method and the other approach is the rule of mixtures. The SMA and SMP constitutive models are validated independently with experimental results. However, the validation of the composite model is performed using the two homogenization approaches and a close agreement in results is observed. Results regarding the isothermal and thermomechanical stress–strain responses are analyzed as a function of SMA volume fraction. Further, it is concluded that the proposed composite model is able to reproduce consistently the overall composite response by taking into consideration not only the phase transformations, variable modulus and transformation stresses in SMA but also the variable modulus, the evolution of stored strain and thermal strain in the SMP

  2. The Piezo Actuator-Driven Pulsed Water Jet System for Minimizing Renal Damage after Off-Clamp Laparoscopic Partial Nephrectomy.

    Science.gov (United States)

    Kamiyama, Yoshihiro; Yamashita, Shinichi; Nakagawa, Atsuhiro; Fujii, Shinji; Mitsuzuka, Koji; Kaiho, Yasuhiro; Ito, Akihiro; Abe, Takaaki; Tominaga, Teiji; Arai, Yoichi

    2017-09-01

    In the setting of partial nephrectomy (PN) for renal cell carcinoma, postoperative renal dysfunction might be caused by surgical procedure. The aim of this study was to clarify the technical safety and renal damage after off-clamp laparoscopic PN (LPN) with a piezo actuator-driven pulsed water jet (ADPJ) system. Eight swine underwent off-clamp LPN with this surgical device, while off-clamp open PN was also performed with radio knife or soft coagulation. The length of the removed kidney was 40 mm, and the renal parenchyma was dissected until the renal calyx became clearly visible. The degree of renal degeneration from the resection surface was compared by Hematoxylin-Eosin staining and immunostaining for 1-methyladenosine, a sensitive marker for the ischemic tissue damage. The mRNA levels of neutrophil gelatinase-associated lipocalin (Ngal), a biomarker for acute kidney injury, were measured by quantitative real-time PCR. Off-clamp LPN with ADPJ system was successfully performed while preserving fine blood vessels and the renal calix with little bleeding. In contrast to other devices, the resection surface obtained with the ADPJ system showed only marginal degree of ischemic changes. Indeed, the expression level of Ngal mRNA was lower in the resection surface obtained with the ADPJ system than that with soft coagulation (p = 0.02). Furthermore, using the excised specimens of renal cell carcinoma, we measured the breaking strength at each site of the human kidney, suggesting the applicability of this ADPJ to clinical trials. In conclusion, off-clamp LPN with the ADPJ system could be safely performed with attenuated renal damage.

  3. Graphene quantum dots-three-dimensional graphene composites for high-performance supercapacitors.

    Science.gov (United States)

    Chen, Qing; Hu, Yue; Hu, Chuangang; Cheng, Huhu; Zhang, Zhipan; Shao, Huibo; Qu, Liangti

    2014-09-28

    Graphene quantum dots (GQDs) have been successfully deposited onto the three-dimensional graphene (3DG) by a benign electrochemical method and the ordered 3DG structure remains intact after the uniform deposition of GQDs. In addition, the capacitive properties of the as-formed GQD-3DG composites are evaluated in symmetrical supercapacitors. It is found that the supercapacitor fabricated from the GQD-3DG composite is highly stable and exhibits a high specific capacitance of 268 F g(-1), representing a more than 90% improvement over that of the supercapacitor made from pure 3DG electrodes (136 F g(-1)). Owing to the convenience of the current method, it can be further used in other well-defined electrode materials, such as carbon nanotubes, carbon aerogels and conjugated polymers to improve the performance of the supercapacitors.

  4. Micromechanical Models of Mechanical Response of High Performance Fibre Reinforced Cement Composites

    DEFF Research Database (Denmark)

    Li, V. C.; Mihashi, H.; Alwan, J.

    1996-01-01

    generation of FRC with high performance and economical viability, is in sight. However, utilization of micromechanical models for a more comprehensive set of important HPFRCC properties awaits further investigations into fundamental mechanisms governing composite properties, as well as intergrative efforts......The state-of-the-art in micromechanical modeling of the mechanical response of HPFRCC is reviewed. Much advances in modeling has been made over the last decade to the point that certain properties of composites can be carefully designed using the models as analytic tools. As a result, a new...... across responses to different load types. Further, micromechanical models for HPFRCC behavior under complex loading histories, including those in fracture, fatigue and multuaxial loading are urgently needed in order to optimize HPFRCC microstrcuctures and enable predictions of such material in structures...

  5. Photorefractive performance of polymer composite sensitized by CdSe nanoparticles passivated by 1-hexadecylamine

    Science.gov (United States)

    Aslam, Farzana; Binks, David J.; Rahn, Mark D.; West, David P.; O'Brien, Paul; Pickett, Nigel

    2005-07-01

    The performance of a photorefractive polymer composite sensitized by 1-hexadecylamine capped CdSe nanoparticles is reported. The polymer composite also comprises the charge transporting matrix poly(N-vinylcarbazole) and the electro-optic chromophore 1-(2-ethylhexyloxy)-2,5-dimethyl-4-(4-nitrophenylazo) benzene. At an applied field of 70?V?µ m-1 two beam coupling gain of 13.2?cm-1 was observed, confirming the photorefractive nature of the induced grating. At the same field, a holographic contrast of 9.12×10-4±6×10-6, a photorefractive sensitivity of 5.1×10-4 ±0.2×10-4?cm3?J-1 and a space-charge field rise time of 13±1?s were obtained.

  6. Walker Branch Throughfall Displacement Experiment Data Report: Site Characterization, System Performance, Weather, Species Composition, and Growth

    Energy Technology Data Exchange (ETDEWEB)

    Hanson, P.J.

    2001-09-04

    This numeric data package provides data sets, and accompanying documentation, on site characterization, system performance, weather, species composition, and growth for the Throughfall Displacement Experiment, which was established in the Walker Branch Watershed of East Tennessee to provide data on the responses of forests to altered precipitation regimes. The specific data sets include soil water content and potential, coarse fraction of the soil profile, litter layer temperature, soil temperature, monthly weather, daily weather, hourly weather, species composition of trees and saplings, mature tree and sapling annual growth, and relative leaf area index. Fortran and SAS{trademark} access codes are provided to read the ASCII data files. The data files and this documentation are available without charge on a variety of media and via the Internet from the Carbon Dioxide Information Analysis Center (CDIAC).

  7. Colloidal processing and CO_2-capture performance Al_2O_3-zeolite 13X composites

    International Nuclear Information System (INIS)

    Andersson, L.; Akhtar, F.; Ojuva, A.; Bergstroem, L.

    2012-01-01

    Hierarchically porous composites for CO_2-capture have been produced by coating the inner walls of foam-like macroporous alumina monoliths, produced by templated synthesis, with microporous zeolite 13X particles. Homogeneous and dense coatings of the particulate adsorbent were obtained when the impregnation process was performed at a pH above 9. At this pH-level the colloidally stable suspensions of the negatively charged zeolite 13X particles could fill all the voids of the highly connected pore space of the alumina supports and attach to the monolith walls, which had been pre-coated with poly(ethylene imine). A CO_2-uptake as high as 5 mmol CO_2/g zeolite 13X was achieved for alumina-zeolite 13X composites through minimisation of the added inorganic binder, kaolin, to only 3.0 wt% with respect to zeolite content, and through optimisation of the thermal treatment.

  8. The performance of integrated active fiber composites in carbon fiber laminates

    International Nuclear Information System (INIS)

    Melnykowycz, M; Brunner, A J

    2011-01-01

    Piezoelectric elements integrated into fiber-reinforced polymer-matrix laminates can provide various functions in the resulting adaptive or smart composite. Active fiber composites (AFC) composed of lead zirconate titanate (PZT) fibers can be used as a component in a smart material system, and can be easily integrated into woven composites. However, the impact of integration on the device and its functionality has not been fully investigated. The current work focuses on the integration and performance of AFC integrated into carbon-fiber-reinforced plastic (CFRP) laminates, focusing on the strain sensor performance of the AFC–CFRP laminate under tensile loading conditions. AFC were integrated into cross-ply CFRP laminates using simple insertion and interlacing of the CFRP plies, with the AFC always placed in the 90° ply cutout area. Test specimens were strained to different strain levels and then cycled with a 0.01% strain amplitude, and the resulting signal from the AFC was monitored. Acoustic emission monitoring was performed during tensile testing to provide insight to the failure characteristics of the PZT fibers. The results were compared to those from past studies on AFC integration; the strain signal of AFC integrated into CFRP was much lower than that for AFC integrated into woven glass fiber laminates. However, the profiles of the degradations of the AFC signal resulting from the strain were nearly identical, showing that the PZT fibers fragmented in a similar manner for a given global strain. The sensor performance recovered upon unloading, which is attributed to the closure of cracks between PZT fiber fragments

  9. Lateral nanowire/nanobelt based nanogenerators, piezotronics and piezo-phototronics

    KAUST Repository

    Wang, Zhong Lin

    2010-11-01

    Relying on the piezopotential created in ZnO under straining, nanogenerators, piezotronics and piezo-phototronics developed based on laterally bonded nanowires on a polymer substrate have been reviewed. The principle of the nanogenerator is a transient flow of electrons in external load as driven by the piezopotential created by dynamic straining. By integrating the contribution made by millions of nanowires, the output voltage has been raised to 1.2 V. Consequently, self-powered nanodevices have been demonstrated. This is an important platform technology for the future sensor network and the internet of things. Alternatively, the piezopotential can act as a gate voltage that can tune/gate the transport process of the charge carriers in the nanowire, which is a gate-electrode free field effect transistor (FET). The device fabricated based on this principle is called the piezotronic device. Piezo-phototronic effect is about the tuning and controlling of electro-optical processes by strain induced piezopotential. The piezotronic, piezophotonic and pieozo-phototronic devices are focused on low frequency applications in areas involving mechanical actions, such as MEMS/NEMS, nanorobotics, sensors, actuators and triggers. © 2010 Elsevier B.V. All rights reserved.

  10. Design issues of the piezo motor for the spacecraft reflector control system

    Directory of Open Access Journals (Sweden)

    Azin Anton

    2018-01-01

    Full Text Available Creation of large-size reflectors for spacecrafts is a topical issue for the space industry. The accuracy of the reflecting surface form and the structure weight are the main criteria for the reflector design. The accuracy of the reflecting surface form during a long-term operation is provided by adjustment when using piezoelectric motors in the reflector design. These motors have small weight-size parameters and can reach great torque values. The piezo motor is a distributed mechanical-acoustic oscillation system. Mechanical-acoustic oscillations are generated in the piezo motor by a PZT-stack and transmitted to an oscillator element, and then from the oscillator element to a load action element. At high frequencies, when dimensions of the oscillator are proportionate to the wavelength, the energy is transmitted by means of acoustic waves. In this case, mechanical waves practically are not involved in the energy transmission process. This thesis shows a method for selecting the material of a mechanical-acoustic oscillation system according to the efficiency of the acoustic energy transmission via a piezoelectric layered structure.

  11. Integral force feedback control with input shaping: Application to piezo-based scanning systems in ECDLs

    Science.gov (United States)

    Zhang, Meng; Liu, Zhigang; Zhu, Yu; Bu, Mingfan; Hong, Jun

    2017-07-01

    In this paper, a hybrid control system is developed by integrating the closed-loop force feedback and input shaping method to overcome the problem of the hysteresis and dynamic behavior in piezo-based scanning systems and increase the scanning speed of tunable external cavity diode lasers. The flexible hinge and piezoelectric actuators are analyzed, and a dynamic model of the scanning systems is established. A force sensor and an integral controller are utilized in integral force feedback (IFF) to directly augment the damping of the piezoelectric scanning systems. Hysteresis has been effectively eliminated, but the mechanical resonance is still evident. Noticeable residual vibration occurred after the inflection points and then gradually disappeared. For the further control of mechanical resonance, based on the theory of minimum-acceleration trajectory planning, the time-domain input shaping method was developed. The turning sections of a scanning trajectory are replaced by smooth curves, while the linear sections are retained. The IFF method is combined with the input shaping method to control the non-linearity and mechanical resonance in high-speed piezo-based scanning systems. Experiments are conducted, and the results demonstrate the effectiveness of the proposed control approach.

  12. Active Damping of a Piezoelectric Tube Scanner using Self-Sensing Piezo Actuation

    Science.gov (United States)

    Kuiper, S.; Schitter, G.

    2010-01-01

    In most Atomic Force Microscopes (AFM), a piezoelectric tube scanner is used to position the sample underneath the measurement probe. Oscillations stemming from the weakly damped resonances of the tube scanner are a major source of image distortion, putting a limitation on the achievable imaging speed. This paper demonstrates active damping of these oscillations in multiple scanning axes without the need for additional position sensors. By connecting the tube scanner in a capacitive bridge circuit the scanner oscillations can be measured in both scanning axes, using the same piezo material as an actuator and sensor simultaneously. In order to compensate for circuit imbalance caused by hysteresis in the piezo element, an adaptive balancing circuit is used. The obtained measurement signal is used for feedback control, reducing the resonance peaks in both scanning axes by 18 dB and the cross-coupling at those frequencies by 30 dB. Experimental results demonstrate a significant reduction in scanner oscillations when applying the typical triangular scanning signals, as well as a strong reduction in coupling induced oscillations. Recorded AFM images show a considerable reduction in image distortion due to the proposed control method, enabling artifact free AFM imaging at a speed of 122 lines per second with a standard piezoelectric tube scanner. PMID:26412944

  13. Integral force feedback control with input shaping: Application to piezo-based scanning systems in ECDLs.

    Science.gov (United States)

    Zhang, Meng; Liu, Zhigang; Zhu, Yu; Bu, Mingfan; Hong, Jun

    2017-07-01

    In this paper, a hybrid control system is developed by integrating the closed-loop force feedback and input shaping method to overcome the problem of the hysteresis and dynamic behavior in piezo-based scanning systems and increase the scanning speed of tunable external cavity diode lasers. The flexible hinge and piezoelectric actuators are analyzed, and a dynamic model of the scanning systems is established. A force sensor and an integral controller are utilized in integral force feedback (IFF) to directly augment the damping of the piezoelectric scanning systems. Hysteresis has been effectively eliminated, but the mechanical resonance is still evident. Noticeable residual vibration occurred after the inflection points and then gradually disappeared. For the further control of mechanical resonance, based on the theory of minimum-acceleration trajectory planning, the time-domain input shaping method was developed. The turning sections of a scanning trajectory are replaced by smooth curves, while the linear sections are retained. The IFF method is combined with the input shaping method to control the non-linearity and mechanical resonance in high-speed piezo-based scanning systems. Experiments are conducted, and the results demonstrate the effectiveness of the proposed control approach.

  14. Omnidirectional piezo-optical ring sensor for enhanced guided wave structural health monitoring

    International Nuclear Information System (INIS)

    Giurgiutiu, Victor; Roman, Catalin; Lin, Bin; Frankforter, Erik

    2015-01-01

    This paper presents a novel method for the detection of ultrasonic waves from acoustic emission events using piezoelectric wafer ac3tive sensors (PWAS) and optical fiber Bragg grating (FBG) sensing combined with mechanical resonance amplification principles. The method is best suited for detecting the out-of-plane motion of the AE wave with preference for a certain frequency that can be adjusted by design. Several issues are discussed: (a) study the mode shapes of the sensors under different resonance frequencies in order to understand the behavior of the ring in a frequency band of interest; (b) comparison of analytical results and mode shapes with FEM predictions; (c) choice of the final piezo-optical ring sensor shape; (d) testing of the piezo-optical ring sensor prototype; (e) discussion of the ring-sensor test results in comparison with conventional results from PWAS and FBG sensors mounted directly on the test structure. The paper ends with summary, conclusions, and suggestions for further work. (paper)

  15. Piezo-optic tensor of crystals from quantum-mechanical calculations.

    Science.gov (United States)

    Erba, A; Ruggiero, M T; Korter, T M; Dovesi, R

    2015-10-14

    An automated computational strategy is devised for the ab initio determination of the full fourth-rank piezo-optic tensor of crystals belonging to any space group of symmetry. Elastic stiffness and compliance constants are obtained as numerical first derivatives of analytical energy gradients with respect to the strain and photo-elastic constants as numerical derivatives of analytical dielectric tensor components, which are in turn computed through a Coupled-Perturbed-Hartree-Fock/Kohn-Sham approach, with respect to the strain. Both point and translation symmetries are exploited at all steps of the calculation, within the framework of periodic boundary conditions. The scheme is applied to the determination of the full set of ten symmetry-independent piezo-optic constants of calcium tungstate CaWO4, which have recently been experimentally reconstructed. Present calculations unambiguously determine the absolute sign (positive) of the π61 constant, confirm the reliability of 6 out of 10 experimentally determined constants and provide new, more accurate values for the remaining 4 constants.

  16. Piezo-sensor self-diagnostics using electrical impedance measurements.

    Energy Technology Data Exchange (ETDEWEB)

    Park, G. H. (Gyu Hae); Farrar, C. R. (Charles R.); Rutherford, A. C. (Amanda C.); Robertson, A. N. (Amy N.)

    2004-01-01

    This paper present the piezoelectric sensor self-diagnostic procedure that performs in-situ monitoring of the operational status of piezoelectric materials (PZT) used for sensors and actuators in structural health monitoring (SHM) applications. The use of active-sensing piezoelectric materials has received considerable attention in the SHM community. A critical aspect of the piezoelectric active-sensing technologies is that usually large numbers of distributed sensors and actuators are needed to perform the required monitoring process. The sensor/actuator self-diagnostic procedure, where the sensors/actuators are confirmed to be functioning properly during operation, is therefore a critical component to successfully complete the SHM process and to minimize the false indication regarding the structural health. The basis of this procedure is to track the changes in the capacitive value of piezoelectric materials resulting from the sensor failure, which is manifested in the imaginary part of the measured electrical admittances. Furthermore, through the analytical and experimental investigation, it is confirmed that the bonding layer between the PZT and a host structure significantly contributes to the measured capacitive values. Therefore, by monitoring the imaginary part of the admittances, one can quantitatively assess the degradation of the mechanical/electrical properties of the PZT and its attachment to a host structure. This paper concludes with an experimental example to demonstrate the feasibility of the proposed sensor-diagnostic procedure.

  17. High performance all-carbon composite transparent electrodes containing uniform carbon nanotube networks

    Energy Technology Data Exchange (ETDEWEB)

    Yun, Hyung Duk; Kwak, Jinsung; Kim, Se-Yang [School of Materials Science and Engineering & Low-Dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919 (Korea, Republic of); Seo, Han; Bang, In Cheol; Kim, Sung Youb [School of Mechanical and Nuclear Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919 (Korea, Republic of); Kang, Seoktae [Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141 (Korea, Republic of); Kwon, Soon-Yong, E-mail: sykwon@unist.ac.kr [School of Materials Science and Engineering & Low-Dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919 (Korea, Republic of); School of Mechanical and Nuclear Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919 (Korea, Republic of)

    2016-08-05

    Indium tin oxide-free, flexible transparent electrodes (TEs) are crucial for the future commercialization of flexible and wearable electronics. While carbon-based TEs containing carbon nanotube (CNT) networks show promise, they usually exhibit poor dispersion properties, limiting their performance and practicality. In this study, we report a highly efficient and bending durable all-carbon composite TE (ac-TE) that employs uniform CNT networks on a monolayer graphene/polyethylene terephthalate (PET) substrate via a simple air spray deposition method. The air-sprayed CNT/graphene assembly was free-standing on solution, making a polymer-free transfer of carbon composites to target substrates possible. The excellent performance of the ac-TEs was attributed to the uniformly networked CNTs on the polycrystalline graphene with a well-controlled density, effectively bridging the line defects and filling the tears/voids or folds necessarily existing in the as-processed graphene. The sheet resistance of the ac-TEs was increased only 6% from its original value at a bending radius of 2.7 mm, while that of the pristine graphene/PET assembly increased 237%. Mechanical bending of the ac-TEs worsened the electrical performance by only ∼1.7% after 2000 bending cycles at a bending radius of 2.5 mm. Degradation of the performance by the bending was the result of line defects formation in the graphene, demonstrating the potential of the uniform CNT networks to achieve more efficient and flexible carbon-based TEs. Furthermore, the chemically-doped ac-TEs showed commercially suitable electronic and optical properties with much enhanced thermal stability, closer to practical TEs in flexible devices. - Highlights: • Highly efficient and bending durable all-carbon composite transparent electrodes (TEs) are designed. • The performance was strongly dependent on morphology of CNT networks on graphene. • The mechanism relies on the defect reductions in graphene by uniform CNT coating

  18. High performance all-carbon composite transparent electrodes containing uniform carbon nanotube networks

    International Nuclear Information System (INIS)

    Yun, Hyung Duk; Kwak, Jinsung; Kim, Se-Yang; Seo, Han; Bang, In Cheol; Kim, Sung Youb; Kang, Seoktae; Kwon, Soon-Yong

    2016-01-01

    Indium tin oxide-free, flexible transparent electrodes (TEs) are crucial for the future commercialization of flexible and wearable electronics. While carbon-based TEs containing carbon nanotube (CNT) networks show promise, they usually exhibit poor dispersion properties, limiting their performance and practicality. In this study, we report a highly efficient and bending durable all-carbon composite TE (ac-TE) that employs uniform CNT networks on a monolayer graphene/polyethylene terephthalate (PET) substrate via a simple air spray deposition method. The air-sprayed CNT/graphene assembly was free-standing on solution, making a polymer-free transfer of carbon composites to target substrates possible. The excellent performance of the ac-TEs was attributed to the uniformly networked CNTs on the polycrystalline graphene with a well-controlled density, effectively bridging the line defects and filling the tears/voids or folds necessarily existing in the as-processed graphene. The sheet resistance of the ac-TEs was increased only 6% from its original value at a bending radius of 2.7 mm, while that of the pristine graphene/PET assembly increased 237%. Mechanical bending of the ac-TEs worsened the electrical performance by only ∼1.7% after 2000 bending cycles at a bending radius of 2.5 mm. Degradation of the performance by the bending was the result of line defects formation in the graphene, demonstrating the potential of the uniform CNT networks to achieve more efficient and flexible carbon-based TEs. Furthermore, the chemically-doped ac-TEs showed commercially suitable electronic and optical properties with much enhanced thermal stability, closer to practical TEs in flexible devices. - Highlights: • Highly efficient and bending durable all-carbon composite transparent electrodes (TEs) are designed. • The performance was strongly dependent on morphology of CNT networks on graphene. • The mechanism relies on the defect reductions in graphene by uniform CNT coating

  19. Structural Health Monitoring with Fiber Bragg Grating and Piezo Arrays

    Science.gov (United States)

    Black, Richard J.; Faridian, Ferey; Moslehi, Behzad; Sotoudeh, Vahid

    2012-01-01

    Structural health monitoring (SHM) is one of the most important tools available for the maintenance, safety, and integrity of aerospace structural systems. Lightweight, electromagnetic-interference- immune, fiber-optic sensor-based SHM will play an increasing role in more secure air transportation systems. Manufacturers and maintenance personnel have pressing needs for significantly improving safety and reliability while providing for lower inspection and maintenance costs. Undetected or untreated damage may grow and lead to catastrophic structural failure. Damage can originate from the strain/stress history of the material, imperfections of domain boundaries in metals, delamination in multi-layer materials, or the impact of machine tools in the manufacturing process. Damage can likewise develop during service life from wear and tear, or under extraordinary circumstances such as with unusual forces, temperature cycling, or impact of flying objects. Monitoring and early detection are key to preventing a catastrophic failure of structures, especially when these are expected to perform near their limit conditions.

  20. Seating Arrangement, Group Composition and Competition-driven Interaction: Effects on Students' Performance in Physics

    International Nuclear Information System (INIS)

    Roxas, R. M.; Monterola, C.; Carreon-Monterola, S. L.

    2010-01-01

    We probe the effect of seating arrangement, group composition and group-based competition on students' performance in Physics using a teaching technique adopted from Mazur's peer instruction method. Ninety eight lectures, involving 2339 students, were conducted across nine learning institutions from February 2006 to June 2009. All the lectures were interspersed with student interaction opportunities (SIO), in which students work in groups to discuss and answer concept tests. Two individual assessments were administered before and after the SIO. The ratio of the post-assessment score to the pre-assessment score and the Hake factor were calculated to establish the improvement in student performance. Using actual assessment results and neural network (NN) modeling, an optimal seating arrangement for a class was determined based on student seating location. The NN model also provided a quantifiable method for sectioning students. Lastly, the study revealed that competition-driven interactions increase within-group cooperation and lead to higher improvement on the students' performance.

  1. Development of a high-performance composite cathode for LT-SOFC

    Science.gov (United States)

    Lee, Byung Wook

    carried out to develop a high-performance composite cathode, in particular, for LT-SOFC operating 650°C and below since stability and compatibility of the materials in interest are secured at low temperatures. First, a nano-sized pyrochlore bismuth ruthenate (Bi2Ru 2O7 or BRO7 shortly), one of the promising cathode materials, was successfully synthesized using glycine-nitrate combustion (GNC) route. Stoichiometric Bi2Ru2O7 without any impurity phase was achieved with considerably improved processing condition, leading to the crystallite size of ~24nm in diameter. Even though the resulting powder tends to agglomerate, resulting in overall 200~400nm size range, it still showed better quality than the one prepared by solid state (SS) reaction route followed by extra milling steps such as vibro-milling and sonication for further particle size reduction. Glycine-to-nitrate (G/N) ratio was found to play a critical role in determining the reaction temperature and reaction duration, thus phase purity and particle morphology (particle size, shape, and agglomeration etc). Composite cathodes of such prepared BRO7 (GNC BRO7) combined with SS erbia-stabilized bismuth oxide, Bi1.6Er0.4O3 or ESB, showed better electrochemical performance than vibro-milled BRO7 (VM BRO7)-SS ESB. ASR values of 0.123Ocm2 at 700°C and 4.59cOm 2 at 500°C, respectively, were achieved, which follows well the trend of particle size effect on performance of composite cathodes. Additionally, the number of processing steps (thus time) was reduced by GNC route. Several issues in regard to synthesis process and characteristics of BRO7 material itself will be addressed in this dissertation. Secondly, a unique in-situ composite cathode synthesis was successfully developed and applied for BRO7-ESB composite cathodes to improve percolation and to reduce agglomeration of each phase inside the cathode so that the effective triple phase boundary (TPB) length was extended. To disperse and stabilize ESB powder in de

  2. The effect of breakfast composition and energy contribution on cognitive and academic performance: a systematic review.

    Science.gov (United States)

    Edefonti, Valeria; Rosato, Valentina; Parpinel, Maria; Nebbia, Gabriella; Fiorica, Lorenzo; Fossali, Emilio; Ferraroni, Monica; Decarli, Adriano; Agostoni, Carlo

    2014-08-01

    Most studies that assess the effects of breakfast on subsequent mental abilities compared performance in subjects who had or had not consumed this meal. However, characteristics of breakfast itself may induce metabolic and hormonal alterations of the gastrointestinal tract and potentially modify cognitive performance. Moreover, as far as the evidence on the positive effects of having breakfast is becoming more robust, interest may shift to the specific characteristics of an adequate breakfast. The objective was to summarize existing evidence on the role of nutrient composition or energy intake at breakfast on the accomplishment of school-related tasks and cognition. We conducted a systematic review of the literature through the PubMed database. From the literature search, we identified 102 articles, 15 of which met the inclusion criteria. Of these, 3 studies provided information on the relation between cognitive and academic performance and energy intake at breakfast, 11 provided the same information for the macronutrient composition of breakfast, and 1 investigated both the aspects. Eleven studies considered breakfast meals differing in glycemic index/load. Selected studies were generally carried out in well-nourished children and adults of both sexes from general education. They were mostly experimental studies of short duration and had a limited number of subjects. Cognitive and academic performance was investigated by looking at multiple domains, including memory, attention, reasoning, learning, and verbal and math abilities, with a variety of test batteries scheduled at different time points in the morning. Breakfast options differed in terms of included foods and place and time of administration. There is insufficient quantity and consistency among studies to draw firm conclusions. However, whereas the hypothesis of a better and more sustained performance with a breakfast providing >20% daily energy intake still needs substantiation, there does appear to be

  3. Performance of ground-penetrating radar on granitic regoliths with different mineral composition

    Science.gov (United States)

    Breiner, J.M.; Doolittle, James A.; Horton, Radley M.; Graham, R.C.

    2011-01-01

    Although ground-penetrating radar (GPR) is extensively used to characterize the regolith, few studies have addressed the effects of chemical and mineralogical compositions of soils and bedrock on its performance. This investigation evaluated the performance of GPR on two different granitic regoliths of somewhat different mineralogical composition in the San Jacinto Mountains of southern California. Radar records collected at a site where soils are Alfisols were more depth restricted than the radar record obtained at a site where soils are Entisols. Although the Alfisols contain an argillic horizon, and the Entisols have no such horizon of clay accumulation, the main impact on GPR effectiveness is related to mineralogy. The bedrock at the Alfisol site, which contains more mafic minerals (5% hornblende and 20% biotite), is more attenuating to GPR than the bedrock at the Entisol site, where mafic mineral content is less (<1% hornblende and 10% biotite). Thus, a relatively minor variation in bedrock mineralogy, specifically the increased biotite content, severely restricts the performance of GPR. Copyright ?? 2011 by Lippincott Williams & Wilkins.

  4. Skeletal muscle fiber type composition and performance during repeated bouts of maximal, concentric contractions

    Science.gov (United States)

    Colliander, E. B.; Dudley, G. A.; Tesch, P. A.

    1988-01-01

    Force output and fatigue and recovery patterns were studied during intermittent short-term exercise. 27 men performed three bouts of 30 maximal unilateral knee extensions on 2 different occasions. Blood flow was maintained or occluded during recovery periods (60 s). Blood flow was restricted by inflating a pneumatic cuff placed around the proximal thigh. Muscle biopsies from vastus lateralis were analyzed for identification of fast twitch (FT) and slow twitch (ST) fibers and relative FT area. Peak torque decreased during each bout of exercise and more when blood flow was restricted during recovery. Initial peak torque (IPT) and average peak torque (APT) decreased over the three exercise bouts. This response was 3 fold greater without than with blood flow during recovery. IPT and APT decreased more in individuals with mainly FT fibers than in those with mainly ST fibers. It is suggested that performance during repeated bouts of maximal concentric contractions differs between individuals with different fiber type composition. Specifically, in high intensity, intermittent exercise with emphasis on anaerobic energy release a high FT composition may not necessarily be advantageous for performance.

  5. Copper nanofiber-networked cobalt oxide composites for high performance Li-ion batteries

    Directory of Open Access Journals (Sweden)

    Shim Hee-Sang

    2011-01-01

    Full Text Available Abstract We prepared a composite electrode structure consisting of copper nanofiber-networked cobalt oxide (CuNFs@CoO x . The copper nanofibers (CuNFs were fabricated on a substrate with formation of a network structure, which may have potential for improving electron percolation and retarding film deformation during the discharging/charging process over the electroactive cobalt oxide. Compared to bare CoO x thin-film (CoO x TF electrodes, the CuNFs@CoO x electrodes exhibited a significant enhancement of rate performance by at least six-fold at an input current density of 3C-rate. Such enhanced Li-ion storage performance may be associated with modified electrode structure at the nanoscale, improved charge transfer, and facile stress relaxation from the embedded CuNF network. Consequently, the CuNFs@CoO x composite structure demonstrated here can be used as a promising high-performance electrode for Li-ion batteries.

  6. Performance characterization of active fiber-composite actuators for helicopter rotor blade applications

    Science.gov (United States)

    Wickramasinghe, Viresh K.; Hagood, Nesbitt W.

    2002-07-01

    The primary objective of this work was to characterize the performance of the Active Fiber Composite (AFC) actuator material system for the Boeing Active Material Rotor (AMR) blade application. The AFCs were a new structural actuator system consisting of piezoceramic fibers embedded in an epoxy matrix and sandwiched between interdigitated electrodes to orient the driving electric field in the fiber direction to use the primary piezoelectric effect. These actuators were integrated directly into the blade spar laminate as active plies within the composite structure to perform structural actuation for vibration control in helicopters. Therefore, it was necessary to conduct extensive electromechanical material characterization to evaluate AFCs both as actuators and as structural components of the rotor blade. The characterization tests designed to extract important electromechanical properties under simulated blade operating conditions included stress-strain tests, free strain tests and actuation under tensile load tests. This paper presents the test results as well as the comprehensive testing process developed to evaluate the relevant AFC material properties. The results from this comprehensive performance characterization of the AFC material system supported the design and operation of the Boeing AMR blade scheduled for hover and forward flight wind tunnel tests.

  7. Infrared imaging and acoustic sizing of a bubble inside a micro-electro-mechanical system piezo ink channel

    NARCIS (Netherlands)

    van der Bos, J.A.; van der Bos, Arjan; Segers, Tim; Segers, T.J.; Jeurissen, R.J.M.; van den Berg, Marc; Reinten, Hans; Wijshoff, Herman; Wijshoff, H.; Versluis, Michel; Lohse, Detlef

    2011-01-01

    Piezo drop-on-demand inkjet printers are used in an increasing number of applications because of their reliable deposition of droplets onto a substrate. Droplets of a few picoliters are ejected from an inkjet nozzle at frequencies of up to 100 kHz. However, the entrapment of an air microbubble in

  8. A micro-optical system for endoscopy based on mechanical compensation paradigm using miniature piezo-actuation.

    Science.gov (United States)

    Cerveri, Pietro; Zazzarini, Cynthia Corinna; Patete, Paolo; Baroni, Guido

    2014-06-01

    The goal of the study was to investigate the feasibility of a novel miniaturized optical system for endoscopy. Fostering the mechanical compensation paradigm, the modeled optical system, composed by 14 lenses, separated in 4 different sets, had a total length of 15.55mm, an effective focal length ranging from 1.5 to 4.5mm with a zoom factor of about 2.8×, and an angular field of view up to 56°. Predicted maximum lens travel was less than 3.5mm. The consistency of the image plane height across the magnification range testified the zoom capability. The maximum predicted achromatic astigmatism, transverse spherical aberration, longitudinal spherical aberration and relative distortion were less than or equal to 25μm, 15μm, 35μm and 12%, respectively. Tests on tolerances showed that the manufacturing and opto-mechanics mounting are critical as little deviations from design dramatically decrease the optical performances. However, recent micro-fabrication technology can guarantee tolerances close to nominal design. A closed-loop actuation unit, devoted to move the zoom and the focus lens sets, was implemented adopting miniaturized squiggle piezo-motors and magnetic position encoders based on Hall effect. Performance results, using a prototypical test board, showed a positioning accuracy of less than 5μm along a lens travel path of 4.0mm, which was in agreement with the lens set motion features predicted by the analysis. In conclusion, this study demonstrated the feasibility of the optical design and the viability of the actuation approach while tolerances must be carefully taken into account. Copyright © 2014 IPEM. Published by Elsevier Ltd. All rights reserved.

  9. Performance and Durability of Environmental Barrier Coatings on SiC/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming; Harder, Bryan; Bhatt, Ramakrishna

    2016-01-01

    This presentation highlights advanced environmental barrier coating (EBC) and SiC-SiC Ceramic Matrix Composites (CMC) systems for next generation turbine engines. The emphasis will be placed on fundamental coating and CMC property evaluations; and the integrated system performance and degradation mechanisms in simulated laboratory turbine engine testing environments. Long term durability tests in laser rig simulated high heat flux the rmomechanical creep and fatigue loading conditions will also be presented. The results can help improve the future EBC-CMC system designs, validating the advanced EBC-CMC technologies for hot section turbine engine applications.

  10. Theoretical Rocket Performance of Liquid Methane with Several Fluorine-Oxygen Mixtures Assuming Frozen Composition

    Science.gov (United States)

    Gordon, Sanford; Kastner, Michael E

    1958-01-01

    Theoretical rocket performance for frozen composition during expansion was calculated for liquid methane with several fluorine-oxygen mixtures for a range of pressure ratios and oxidant-fuel ratios. The parameters included are specific impulse, combustion-chamber temperature, nozzle-exit temperature molecular weight, characteristic velocity, coefficient of thrust, ratio of nozzle-exit area to throat area, specific heat at constant pressure, isentropic exponent, viscosity, and thermal conductivity. The maximum calculated value of specific impulse for a chamber pressure of 600 pounds per square inch absolute (40.827atm) and an exit pressure of 1 atmosphere is 315.3 for 79.67 percent fluorine in the oxidant.

  11. Effects of Proteoliposome Composition and Draw Solution Types on Separation Performance of Aquaporin-Based Proteoliposomes

    DEFF Research Database (Denmark)

    Zhao, Yang; Vararattanavech, Ardcharaporn; Li, Xuesong

    2013-01-01

    Escherichia coli cells, and their separation properties were characterized by stopped-flow measurements. The current study systematically investigated the effect of proteoliposome composition (lipid type, protein-to-lipid ratio (PLR), and the addition of cholesterol) on water permeability and NaCl retention......Aquaporins are a large family of water transport proteins in cell membranes. Their high water permeability and solute rejection make them potential building blocks for high-performance biomimetic membranes for desalination. In the current study, proteoliposomes were prepared using AquaporinZ from...

  12. High Photocatalytic Performance of Two Types of Graphene Modified TiO2 Composite Photocatalysts

    Science.gov (United States)

    Zhang, Jun; Li, Sen; Tang, Bo; Wang, Zhengwei; Ji, Guojian; Huang, Weiqiu; Wang, Jinping

    2017-07-01

    High quality and naturally continuous structure of three-dimensional graphene network (3DGN) endow it a promising candidate to modify TiO2. Although the resulting composite photocatalysts display outstanding performances, the lacking of active sites of the 3DGN not only goes against a close contact between the graphene basal plane and TiO2 nanoparticles (weaken electron transport ability) but also limits the efficient adsorption of pollutant molecules. Similar with surface functional groups of the reduced graphene oxide (RGO) nanosheets, surface defects of the 3DGN can act as the adsorption sites. However, the defect density of the 3DGN is difficult to control (a strict cool rate of substrate and a strict flow of precursor gas are necessary) because of its growth approach (chemical vapor deposition method). In this study, to give full play to the functions of graphene, the RGO nanosheets and 3DGN co-modified TiO2 composite photocatalysts are prepared. After optimizing the mass fraction of the RGO nanosheets in the composite photocatalyst, the resulting chemical adsorption ability and yields of strong oxidizing free radicals increase significantly, indicating the synergy of the RGO nanosheets and 3DGN.

  13. Does fasting during Ramadan alter body composition, blood constituents and physical performance?

    Science.gov (United States)

    Ramadan, J

    2002-01-01

    To study the effect of Ramadan fast (RF) on body composition, plasma constituents, hematology, and cardiorespiratory responses to constant submaximal exercise. Sixteen sedentary healthy Kuwaiti adult males were included in the study. The subjects were tested under thermo-neutral conditions during a spring-like month of Ramadan and 2 months thereafter. They were tested during the week before RF (Pre1); the last 3 days of RF (End1); the week before a non-Ramadan month (Pre2), and the last 3 days of the non-Ramadan month (End2). The following measurements were made: body composition, cellular and biochemical constituents of blood, heart rate, ventilatory responses and blood pressure. No significant changes were observed in body composition, cellular and biochemical constituents of blood. The heart rate and ventilatory responses to the moderately intense bouts of submaximal aerobic exercise ( approximately 70% of VO(2max)) were significantly reduced (p Ramadan fasting had no adverse effect on the subjects when performing aerobic exercise at submaximal level. The mild changes in cardiorespiratory responses could be due to dehydration, abstention from consumption of substances with negative inotropy and circadian rhythms. Copyright 2002 S. Karger AG, Basel

  14. Compressive performance and crack propagation in Al alloy/Ti{sub 2}AlC composites

    Energy Technology Data Exchange (ETDEWEB)

    Hanaor, D.A.H., E-mail: dorian.hanaor@sydney.edu.au [School of Civil Engineering, University of Sydney, Sydney, NSW 2006 (Australia); Hu, L. [Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011 (United States); Kan, W.H.; Proust, G. [School of Civil Engineering, University of Sydney, Sydney, NSW 2006 (Australia); Foley, M. [Australian Centre for Microscopy and Microanalysis, University of Sydney, Sydney, NSW 2006 (Australia); Karaman, I.; Radovic, M. [Department of Materials Science and Engineering, Texas A& M University, College Station, TX 77843 (United States)

    2016-08-30

    Composite materials comprising a porous Ti{sub 2}AlC matrix and Al 6061 alloy were fabricated by a current-activated pressure assisted melt infiltration process. Coarse, medium and fine meso-structures were prepared with Al alloy filled pores of differing sizes. Materials were subjected to uniaxial compressive loading up to stresses of 668 MPa, leading to the failure of specimens through crack propagation in both phases. As-fabricated and post-failure specimens were analysed by X-ray microscopy and electron microscopy. Quasi-static mechanical testing results revealed that compressive strength was the highest in the fine structured composite materials. While the coarse structured specimens exhibited a compressive strength of 80% relative to this. Reconstructed micro-scale X-ray tomography data revealed different crack propagation mechanisms. Large planar shear cracks propagated throughout the fine structured materials while the coarser specimens exhibited networks of branching cracks propagating preferentially along Al alloy-Ti{sub 2}AlC phase interfaces and through shrinkage pores in the Al alloy phase. Results suggest that control of porosity, compensation for Al alloy shrinkage and enhancement of the Al alloy-Ti{sub 2}AlC phase interfaces are key considerations in the design of high performance metal/Ti{sub 2}AlC phase composites.

  15. Towards Enhanced Performance Thin-film Composite Membranes via Surface Plasma Modification

    Science.gov (United States)

    Reis, Rackel; Dumée, Ludovic F.; Tardy, Blaise L.; Dagastine, Raymond; Orbell, John D.; Schutz, Jürg A.; Duke, Mikel C.

    2016-01-01

    Advancing the design of thin-film composite membrane surfaces is one of the most promising pathways to deal with treating varying water qualities and increase their long-term stability and permeability. Although plasma technologies have been explored for surface modification of bulk micro and ultrafiltration membrane materials, the modification of thin film composite membranes is yet to be systematically investigated. Here, the performance of commercial thin-film composite desalination membranes has been significantly enhanced by rapid and facile, low pressure, argon plasma activation. Pressure driven water desalination tests showed that at low power density, flux was improved by 22% without compromising salt rejection. Various plasma durations and excitation powers have been systematically evaluated to assess the impact of plasma glow reactions on the physico-chemical properties of these materials associated with permeability. With increasing power density, plasma treatment enhanced the hydrophilicity of the surfaces, where water contact angles decreasing by 70% were strongly correlated with increased negative charge and smooth uniform surface morphology. These results highlight a versatile chemical modification technique for post-treatment of commercial membrane products that provides uniform morphology and chemically altered surface properties. PMID:27363670

  16. Effect of Montmorillonite Nanogel Composite Fillers on the Protection Performance of Epoxy Coatings on Steel Pipelines.

    Science.gov (United States)

    Atta, Ayman M; El-Saeed, Ashraf M; Al-Lohedan, Hamad A; Wahby, Mohamed

    2017-06-02

    Montmorillonite (MMT) clay mineral is widely used as filler for several organic coatings. Its activity is increased by exfoliation via chemical modification to produce nanomaterials. In the present work, the modification of MMT to form nanogel composites is proposed to increase the dispersion of MMT into epoxy matrices used to fill cracks and holes produced by the curing exotherms of epoxy resins. The dispersion of MMT in epoxy improved both the mechanical and anti-corrosion performance of epoxy coatings in aggressive marine environments. In this respect, the MMT surfaces were chemically modified with different types of 2-acrylamido-2-methyl propane sulfonic acid (AMPS) nanogels using a surfactant-free dispersion polymerization technique. The effect of the chemical structure, nanogel content and the interaction with MMT surfaces on the surface morphology, surface charges and dispersion in the epoxy matrix were investigated for use as nano-filler for epoxy coatings. The modified MMT nanogel epoxy composites showed excellent resistance to mechanical damage and salt spray resistance up to 1000 h. The interaction of MMT nanogel composites with the epoxy matrix and good response of AMPS nanogel to sea water improve their ability to act as self-healing materials for epoxy coatings for steel.

  17. A novel poly(acrylic acid-co-acrylamide)/diatomite composite flocculant with outstanding flocculation performance.

    Science.gov (United States)

    Xu, Kun; Liu, Yao; Wang, Yang; Tan, Ying; Liang, Xuecheng; Lu, Cuige; Wang, Haiwei; Liu, Xiusheng; Wang, Pixin

    2015-01-01

    Series of anionic flocculants with outstanding flocculation performance, poly(acrylic acid-co-acrylamide)/diatomite composite flocculants (PAAD) were successfully prepared through aqueous solution copolymerization and applied to flocculate from oil-field fracturing waste-water. The structure of PAAD was characterized by Fourier transform infra-red spectroscopy, (13)C nuclear magnetic resonance and X-ray diffraction tests, and its properties were systematically evaluated by viscometer, thermogravimetry analysis and flocculation measurements. Furthermore, the influences of various reaction parameters on the apparent viscosity of flocculant solution were studied, and the optimum synthesis condition was determined. The novel composite flocculants exhibited outstanding flocculation properties. Specifically, the dosage of composite flocculants that could make the transmittance of treated wastewater exceed 90% was only approximately 12-35 ppm, which was far lower than that of conventional flocculants. Meanwhile, the settling time was lower than 5 s, which was similar to that of conventional flocculants. This was because PAAD flocculants had a higher absorption capacity, and larger chain extending space than conventional linear flocculants, which could refrain from the entanglement of linear polymer chains and significantly improve flocculation capacity.

  18. Performance Investigation of a Full-Scale Hybrid Composite Bull Gear

    Science.gov (United States)

    LaBerge, Kelsen; Handschuh, Robert; Roberts, Gary; Thorp, Scott

    2016-01-01

    Hybrid composite gears have been investigated as a weight saving technology for rotorcraft transmissions. These gears differ from conventional steel gears in that the structural material between the shaft interface and the gear rim is replaced with a lightweight carbon fiber composite. The work discussed here is an extension of previous coupon level hybrid gear tests to a full-scale bull gear. The NASA Glenn Research Center High-Speed Helical Gear Rig was modified for this program allowing several hybrid gear web configurations to be tested while utilizing the same gear rim. Testing was performed on both a baseline (steel) web configuration and a hybrid (steel-composite)configuration. Vibration, orbit and temperature data were recorded and compared between configurations. Vibration levels did not differ greatly between the hybrid and steel configurations, nor did temperature differential between inlet and outlet. While orbit shape displayed differences between the hybrid and baseline configurations, the general overall amplitude was comparable. The hybrid configuration discussed here successfully ran at 3300 hp(2,460 kW), however, progressive growth of the orbit while running at this test condition discontinued the test. Researchers continue to search for the cause of this orbit shift.

  19. Robust and thermal-enhanced melamine formaldehyde–modified glassfiber composite separator for high-performance lithium batteries

    International Nuclear Information System (INIS)

    Wang, Qingfu

    2015-01-01

    The composite separator of melamine formaldehyde resin coated glass microfiber membrane was prepared for high performance lithium ion battery. It was demonstrated that this composite membranes possessed a significantly enhanced tensile strength and a modified porous structure, compared with that of pristine glass microfiber membrane. Impressive improvements in thermo-stability, with no shrinkage at an elevated temperature of 150 °C. Meanwhile, such composite membrane presented a favorable wettability and remarkable electrochemical stability in commercial liquid electrolyte. In addition, the battery test results of LiCoO 2 /graphite cells proved the composite membrane was a promising separator with an improved cycling performance and rate capability. The cycle performance of LiFePO 4 /Li cells at the elevated temperature of 120 °C demonstrated their excellent safety characteristic as separator in LIB, indicating the composite membrane was a potential separator candidate for high power battery.

  20. Performance of a 1 kW Class Nafion-PTFE Composite Membrane Fuel Cell Stack

    Directory of Open Access Journals (Sweden)

    Pattabiraman Krishnamurthy

    2012-01-01

    Full Text Available Composite membranes have been prepared by impregnation of Nafion into the expanded polytetrafluoroethylene (EPTFE matrix. Nafion loading in the composite membranes was kept constant at 2 mg/cm2. The lower amount of electrolyte per unit area in the composite membranes offers cost advantages compared to conventional membrane of 50 μm thickness with an electrolyte loading of ~9 mg/cm2. Composite membranes (30 μm thickness were found to have higher thermal stability and mechanical strength compared to the conventional membranes (50 μm thickness. The performance of the membrane electrode assembly made with these composite membranes was comparable to that of the conventional membranes. Single cells fabricated from these MEAs were tested for their performance and durability before scaling them up for large area. The performance of a 20-cell stack of active area 330 cm2 fabricated using these membranes is reported.