The Experts below are selected from a list of 7416 Experts worldwide ranked by ideXlab platform
Jae-hwan Kim - One of the best experts on this subject based on the ideXlab platform.
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Enhanced Electromechanical Behavior of cellulose film by zinc oxide nanocoating and its vibration energy harvesting
Acta Materialia, 2016Co-Authors: Seongcheol Mun, Seung Ki Min, Hyun Chan Kim, Joo Hyung Kim, Lindong Zhai, Hyun-u Ko, Jae-hwan KimAbstract:Cellulose has been reported as a renewable smart material useful for sensors and actuators. We report an enhanced Electromechanical Behavior of zinc oxide nanocoated cellulose film (ZONCE). A zinc oxide nanolayer is uniformly formed on the surface of a regenerated cellulose film by using a solution based hydrothermal process. Such a simple ZnO nanolayer deposition of ZONCE shows a drastic improvement of its Electromechanical Behavior. Physical, chemical, electrical, mechanical and Electromechanical characteristics along with the reasons of improved Electromechanical Behavior of ZONCE are discussed in this paper. Using the ZONCE, a vibration energy harvester is demonstrated. It is promising that the ZONCE is easy to fabricate by an inexpensive solution process without sacrificing biocompatibility, transparency, flexibility and low cost.
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Electromechanical Behavior of room temperature ionic liquid dispersed cellulose
Journal of Physical Chemistry C, 2009Co-Authors: Suresha K Mahadeva, Jae-hwan KimAbstract:The effect of 1-butyl-3-methylimidazolium hexafluorophosphate (BMIPF6) dispersion on the structure, thermal stability and Electromechanical Behavior of cellulose was investigated by infrared spectroscopy, X-ray diffraction, thermogravimetry and bending actuation test. Dispersion of BMIPF6 in cellulose matrix was carried out by solution blending technique. Upon dispersion of 20 wt % BMIPF6, the bending displacement of the actuator was enhanced by four times as compared to that of pristine cellulose. However, BMIPF6 dispersion resulted in increased amorphous region and reduced its thermal stability of cellulose. This might be due to interruption of cellulose crystallization by entrapment of BMIPF6 molecules between cellulose layers and weakening of the intra- and intermolecular hydrogen bonds of cellulose. Humidity effect and the durability of the BMIPF6 dispersed cellulose actuator are discussed.
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Effect of Room Temperature Ionic Liquids Adsorption on Electromechanical Behavior of Cellulose Electro-Active Paper
Macromolecular Research, 2009Co-Authors: Suresha K Mahadeva, Chen Yi, Jae-hwan KimAbstract:The cellulose smart material called electro-active paper (EAPap) is made by regenerating cellulose. How-ever, the actuator performance is degraded at low humidity levels. To solve this drawback, EAPap bending actuators were made by activating wet cellulose films in three different room-temperature ionic liquids: 1-butyl-3-methylimidazo-lium hexaflurophosphate (BMIPF 6), 1-butyl-3-methylimidazolium chloride (BMICL) and 1-butyl-3-methylimida-zolium tetrafluroborate (BMIBF 4). In the results, the actuator performance was dependent on the type of anions in the ionic liquids, in the order of BF 4 > Cl > PF 6 . The BMIBF 4 -activated actuator showed the maximum displacement of 3.8 mm with low electrical power consumption at relatively low humidity. However, the BMICL-activated actu-ator showed a slight degradation of actuator performance. Further performance and durability improvement will be possible once various ionic liquids are blended with cellulose.
J Schwartz - One of the best experts on this subject based on the ideXlab platform.
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weibull analysis of the Electromechanical Behavior of agmg sheathed bi2sr2cacu2o8 x round wires and yba2cu3o7 δ coated conductors
Superconductor Science and Technology, 2010Co-Authors: A. Mbaruku, Honghai Song, J SchwartzAbstract:The development of superconducting magnets requires not only a conductor that is capable of carrying sufficient critical current density (Jc) at high magnetic field, but also one that is mechanically robust and predictable. Here, the Electromechanical Behavior of AgMg sheathed Bi2Sr2CaCu2O8 + x (Bi2212) round wires and YBa2Cu3O7 − δ (YBCO) coated conductors is studied using a statistical approach based upon three-parameter Weibull statistics, where the three parameters α, β, and γ describe the scale, shape and location of the resulting distribution function. The results show that Bi2212 round wire has significantly different Behavior than previously studied Bi2212 tape conductors, with evidence of an underlying mechanically strong but poorly connected electrical 'backbone' in the round wire that is not found in the tape conductor. Furthermore, the Bi2212 round wire results indicate a distribution in the dependence of critical current upon strain (Ic(e)) at the microscopic level, consistent with reports that a complex network of interfilamentary bridges plays a key role in connectivity. Unlike the Behavior of either Bi2212 round wire or tape, the YBCO coated conductor shows a universal Behavior for strains below yield, consistent with the presence of a strong, stiff NiW substrate that dominates the mechanical Behavior, and a high purity, high density, highly textured YBCO layer with reversible Electromechanical properties. These results indicate that, in particular for Bi2212 conductors, the strain-dependence of the location parameter, γ(e), which defines the minimum critical current for any segment of conductor at a particular value of strain, is a more important function for magnet design than Ic(e) or the critical strain, ec. Using the approach reported previously and applied here, this curve is readily obtained using a limited length of conductor, but provides an important level of conservatism to the design of magnets using long lengths of conductor.
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statistical analysis of the Electromechanical Behavior of agmg sheathed bi2sr2cacu2o8 x superconducting tapes using weibull distributions
Journal of Applied Physics, 2007Co-Authors: A L Mbaruku, J SchwartzAbstract:Manufacturing of AgMg sheathed Bi2Sr2CaCu2O8+x superconducting tapes involves multiple processes. Microstructural studies across tape sections have shown that the microstructure is nonuniform across the tape. These nonuniformities are largely due to manufacturing defects, even in well-controlled manufacturing processes. Consequently, the electrical and mechanical properties vary in these different sections. Here, we report results from analyzing the Electromechanical properties of AgMg sheathed Bi2Sr2CaCu2O8+x tapes in different sections using a statistical approach. 24 samples were studied at strains of 0%, 0.25%, and 0.349% for a total of 72 samples. The probability of electrical and mechanical failures of the tapes is then analyzed using two- and three-parameter Weibull distributions. It is found that the mechanical failure of these tapes is homogeneous, consistent with failure in the AgMg sheath, but that the Electromechanical failure is inhomogeneous within the conductor and as a function of strain, ...
Y P Shen - One of the best experts on this subject based on the ideXlab platform.
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effects of stress and electric field on the Electromechanical properties of pb mg1 3nb2 3 o3 0 32pbtio3 single crystals
Journal of Applied Physics, 2005Co-Authors: Q Wan, Changqing Chen, Y P ShenAbstract:The effects of constant bias stress and electric field on the Electromechanical Behavior of ⟨001⟩-oriented Pb(Mg1∕3Nb2∕3)O3–0.32PbTiO3 (PMN–0.32PT) relaxor ferroelectric single crystals have been investigated. Both unipolar and bipolar responses are considered. Obtained results show that compressive bias stress with appropriate magnitude can significantly increase the piezoelectric constant. It is also found that bias electric field in the poling direction stabilizes the microstructure of PMN–0.32PT and reduces the hysteresis loss. The observed effects of bias stress and bias electric field on the Electromechanical properties of ⟨001⟩-oriented PMN–0.32PT single crystals can be interpreted in terms of phase-transformation-induced polarization rotation through intermediate phases.
A. Mbaruku - One of the best experts on this subject based on the ideXlab platform.
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weibull analysis of the Electromechanical Behavior of agmg sheathed bi2sr2cacu2o8 x round wires and yba2cu3o7 δ coated conductors
Superconductor Science and Technology, 2010Co-Authors: A. Mbaruku, Honghai Song, J SchwartzAbstract:The development of superconducting magnets requires not only a conductor that is capable of carrying sufficient critical current density (Jc) at high magnetic field, but also one that is mechanically robust and predictable. Here, the Electromechanical Behavior of AgMg sheathed Bi2Sr2CaCu2O8 + x (Bi2212) round wires and YBa2Cu3O7 − δ (YBCO) coated conductors is studied using a statistical approach based upon three-parameter Weibull statistics, where the three parameters α, β, and γ describe the scale, shape and location of the resulting distribution function. The results show that Bi2212 round wire has significantly different Behavior than previously studied Bi2212 tape conductors, with evidence of an underlying mechanically strong but poorly connected electrical 'backbone' in the round wire that is not found in the tape conductor. Furthermore, the Bi2212 round wire results indicate a distribution in the dependence of critical current upon strain (Ic(e)) at the microscopic level, consistent with reports that a complex network of interfilamentary bridges plays a key role in connectivity. Unlike the Behavior of either Bi2212 round wire or tape, the YBCO coated conductor shows a universal Behavior for strains below yield, consistent with the presence of a strong, stiff NiW substrate that dominates the mechanical Behavior, and a high purity, high density, highly textured YBCO layer with reversible Electromechanical properties. These results indicate that, in particular for Bi2212 conductors, the strain-dependence of the location parameter, γ(e), which defines the minimum critical current for any segment of conductor at a particular value of strain, is a more important function for magnet design than Ic(e) or the critical strain, ec. Using the approach reported previously and applied here, this curve is readily obtained using a limited length of conductor, but provides an important level of conservatism to the design of magnets using long lengths of conductor.
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Relationships Between Conductor Damage, Quenching and Electromechanical Behavior in YBCO Coated Conductors
IEEE Transactions on Applied Superconductivity, 2007Co-Authors: A. Mbaruku, Ulf P. Trociewitz, Xiaorong Wang, Justin SchwartzAbstract:The implementation of emerging superconducting materials into magnet systems with long service lifetimes requires a thorough understanding of their engineering properties, including their quench and Electromechanical Behaviors. Furthermore, it is essential to understand the role of defects in the conductor, whether they be pre-existing defects from the conductor manufacturing process that locally reduce Jc, or local defects that result from a non-destructive quench (i.e., a quench that may reduce Jc locally but does not significantly affect the end-to-end Behavior). This paper reports results on both of these types of defects and the interplay between quenching and Electromechanical Behavior. Quench studies investigate the initiation and propagation of quenches in coated conductors. Disturbances in homogeneous conductors are initiated by a pulsed heater attached to the conductor. Disturbances in locally damaged conductors are initiated by increasing the transport current above the Ic at the local defect but below the end-to-end Ic. Samples are quenched to determine the minimum quench energy and the quench propagation velocity. Homogeneous samples are also quenched to the point of initiating local damage, thereby identifying the maximum allowable hot-spot temperature or hot-spot temperature gradient. Samples used in quench studies are subsequently used in Ic-strain measurements to determine how quenching affects subsequent performance. Samples that exhibit reduced Ic from quenching, and samples from regions adjacent to such damaged samples, are studied. It is found that quenching can reduce the Electromechanical performance of conductors that do not initially show a reduction in their electrical performance.
Ichiroh Takeuchi - One of the best experts on this subject based on the ideXlab platform.
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electrochemical impedance spectroscopy and Electromechanical Behavior of bucky gel actuators containing ionic liquids
Journal of Physical Chemistry C, 2010Co-Authors: Ichiroh Takeuchi, Kinji Asaka, Kenji Kiyohara, Takushi Sugino, Ken Mukai, Hyacinthe RandriamahazakaAbstract:In this paper, bucky-gel electrodes containing various ionic liquid species were prepared by casting, using “bucky gel”, a gelatinous room-temperature ionic liquid (IL) containing single-walled carbon nanotubes (SWCNT). Their electrochemical impedance responses were measured and analyzed. Also, the Electromechanical responses of the actuators composed of two bucky-gel electrodes sandwiching an ionic liquid gel layer were studied by measuring the displacement due to an applied sinusoidal voltage at various frequencies. All impedance data were successfully simulated by the equivalent circuit model of a porous electrode based on the transmission line circuit model. By using the same parameter values of the porous electrode model, the frequency dependence of the strain generated in the bucky-gel actuators can be simulated. On the basis of the experimental and simulation results, the Electromechanical responses of the bucky-gel actuator were analyzed by taking into account the electrochemical properties of the...
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Electromechanical Behavior of a fully plastic actuator based on dispersed nano carbon ionic liquid gel electrodes
Carbon, 2009Co-Authors: Ichiroh Takeuchi, Kinji Asaka, Kenji Kiyohara, Takushi Sugino, Ken Mukai, Naohiro Terasawa, Soshi ShiraishiAbstract:Abstract A bucky-gel actuator based on active electrodes composed of activated carbon nanofibers (ACNFs), ionic liquids (ILs) and poly (vinylidene fluoride-co-hexafluoropropylene (PVdF(HFP)) as polymer support have been developed (ACNF-actuator). The frequency dependence of the displacement was measured for the actuators containing seven kinds of ILs. The frequency responses of the ACNF-actuators were one order of magnitude lower than those of the SWCNT-actuators. The reason for this is attributed to the lower conductivity of the ACNF-electrode. In order to improve the response of the ACNF-actuator, the electrode of the actuator was optimized by mixing the ACNFs with SWCNTs (ACNF–SWCNT electrode) or vapor grown carbon fibers (VGCFs) (ACNF–VGCF electrode) for the purpose of increasing the conductivity of the electrode. We have improved the performance of the actuator by optimizing the ratio of the two carbons. We are thus able to tune nano-carbon materials for specific applications of the Electromechanical actuator.
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Electromechanical Behavior of fully plastic actuators based on bucky gel containing various internal ionic liquids
Electrochimica Acta, 2009Co-Authors: Ichiroh Takeuchi, Kinji Asaka, Kenji Kiyohara, Takushi Sugino, Ken Mukai, Naohiro Terasawa, Takanori Fukushima, Takuzo AidaAbstract:Abstract In the previous papers, we have reported the first dry actuator that can be fabricated simply by layer-by-layer casting, using ‘bucky gel’, a gelatinous room-temperature ionic liquid (IL) containing single-walled carbon nanotubes (SWNTs). In this paper, the Electromechanical and electrochemical properties of the bucky-gel actuators composed of the bucky-gel electrode and the gel electrolyte layers containing seven kinds of internal ILs were studied for exploring the details of the actuation mechanism. We measured the frequency dependence of the displacement response of the bucky-gel actuator and it can be successfully simulated by the electrochemical kinetic model. From the simulated result for the frequency dependence of the Electromechanical response of the bucky-gel actuators, we determined two parameters for the simulation, the generated strain at a limit of low frequency and the time constant. The time constant was represented by the equivalent circuit composed of series combination of the ionic resistance R, the double-layer capacitance C and the electrode resistance Rel. The IL-dependence of the time constant was determined by that of the ionic resistance R of the gel electrolyte layer. The generated strain at a limit of low frequency is considered to be related to the Electromechanical mechanism of the bucky-gel actuator. From their dependence on the IL species and the theoretical modeling reported in the previous papers, we conclude that both the steric repulsion effect due to the transfer of ions to the electrode and ‘the charge injection’ give the bending motion of the bucky-gel actuator. The volume-changes of the cathode and anode change according to the sizes of the cation and anion, respectively. The ion size gives the dependence of the bending motion of the bucky-gel actuator on the internal ionic species.
