The Experts below are selected from a list of 288 Experts worldwide ranked by ideXlab platform
Kenya Hashimoto - One of the best experts on this subject based on the ideXlab platform.
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enhancement of effective electromechanical Coupling Factor by mass loading in layered surface acoustic wave device structures
Japanese Journal of Applied Physics, 2016Co-Authors: Gongbin Tang, Tao Han, Akihiko Teshigahara, Takao Iwaki, Kenya HashimotoAbstract:This paper describes a drastic enhancement of the effective Coupling Factor by mass loading in layered surface acoustic wave (SAW) device structures such as the ScAlN film/Si substrate structure. This phenomenon occurs when the piezoelectric layer exhibits a high acoustic wave velocity. The mass loading decreases the SAW velocity and causes SAW energy confinement close to the top surface where an interdigital transducer is placed. It is shown that this phenomenon is obvious even when an amorphous SiO2 film is deposited on the top surface for temperature compensation. This enhancement was also found in various combinations of electrode, piezoelectric layer, and/or substrate materials. The existence of this phenomenon was verified experimentally using the ScAlN film/Si substrate structure.
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enhanced Coupling Factor of surface acoustic wave devices employing scaln diamond layered structure with embedded electrodes
Diamond and Related Materials, 2015Co-Authors: Qiaozhen Zhang, Tao Han, Jing Chen, Weibiao Wang, Kenya HashimotoAbstract:Abstract A layered structure ScAlN/diamond configured with embedded electrodes is studied for high frequency and wide band SAW devices. Theoretical studies are performed to calculate the phase velocity and K 2 dispersion curves of the Rayleigh mode and its higher modes. The influences of various ScAlN film thickness and electrode thickness as well as different electrode materials on K 2 are also investigated. The maximum electromechanical Coupling Factor ( K 2 ) of surface acoustic wave (SAW) resonator based on such structure has been theoretically shown up to be 14.5%, which is about 2.5 times larger than the previously reported. Such an enhancement of K 2 makes this layered structure great potential application to ultrawide band SAW filters operating in 2–3 GHz range.
Seungyoung Ahn - One of the best experts on this subject based on the ideXlab platform.
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Effect of ferrite addition above the base ferrite on the Coupling Factor of wireless power transfer for vehicle applications
Journal of Applied Physics, 2015Co-Authors: Tushar Batra, Erik Schaltz, Seungyoung AhnAbstract:Power transfer capability of wireless power transfer systems is highly dependent on the magnetic design of the primary and secondary inductors and is measured quantitatively by the Coupling Factor. The inductors are designed by placing the coil over a ferrite base to increase the Coupling Factor and reduce magnetic emissions to the surroundings. Effect of adding extra ferrite above the base ferrite at different physical locations on the self-inductance, mutual inductance, and Coupling Factor is under investigation in this paper. The addition can increase or decrease the mutual inductance depending on the placement of ferrite. Also, the addition of ferrite increases the self-inductance of the coils, and there is a probability for an overall decrease in the Coupling Factor. Correct placement of ferrite, on the other hand, can increase the Coupling Factor relatively higher than the base ferrite as it is closer to the other inductor. Ferrite being a heavy compound of iron increases the inductor weight signifi...
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effect of ferrite addition above the base ferrite on the Coupling Factor of wireless power transfer for vehicle applications
Journal of Applied Physics, 2015Co-Authors: Tushar Batra, Erik Schaltz, Seungyoung AhnAbstract:Power transfer capability of wireless power transfer systems is highly dependent on the magnetic design of the primary and secondary inductors and is measured quantitatively by the Coupling Factor. The inductors are designed by placing the coil over a ferrite base to increase the Coupling Factor and reduce magnetic emissions to the surroundings. Effect of adding extra ferrite above the base ferrite at different physical locations on the self-inductance, mutual inductance, and Coupling Factor is under investigation in this paper. The addition can increase or decrease the mutual inductance depending on the placement of ferrite. Also, the addition of ferrite increases the self-inductance of the coils, and there is a probability for an overall decrease in the Coupling Factor. Correct placement of ferrite, on the other hand, can increase the Coupling Factor relatively higher than the base ferrite as it is closer to the other inductor. Ferrite being a heavy compound of iron increases the inductor weight significantly and needs to be added judiciously. Four zones have been identified in the paper, which shows different sensitivity to addition of ferrite in terms of the two inductances and Coupling Factor. Simulation and measurement results are presented for different air gaps between the coils and at different gap distances between the ferrite base and added ferrite. This paper is beneficial in improving the Coupling Factor while adding minimum weight to wireless power transfer system.
Tao Han - One of the best experts on this subject based on the ideXlab platform.
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enhancement of effective electromechanical Coupling Factor by mass loading in layered surface acoustic wave device structures
Japanese Journal of Applied Physics, 2016Co-Authors: Gongbin Tang, Tao Han, Akihiko Teshigahara, Takao Iwaki, Kenya HashimotoAbstract:This paper describes a drastic enhancement of the effective Coupling Factor by mass loading in layered surface acoustic wave (SAW) device structures such as the ScAlN film/Si substrate structure. This phenomenon occurs when the piezoelectric layer exhibits a high acoustic wave velocity. The mass loading decreases the SAW velocity and causes SAW energy confinement close to the top surface where an interdigital transducer is placed. It is shown that this phenomenon is obvious even when an amorphous SiO2 film is deposited on the top surface for temperature compensation. This enhancement was also found in various combinations of electrode, piezoelectric layer, and/or substrate materials. The existence of this phenomenon was verified experimentally using the ScAlN film/Si substrate structure.
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enhanced Coupling Factor of surface acoustic wave devices employing scaln diamond layered structure with embedded electrodes
Diamond and Related Materials, 2015Co-Authors: Qiaozhen Zhang, Tao Han, Jing Chen, Weibiao Wang, Kenya HashimotoAbstract:Abstract A layered structure ScAlN/diamond configured with embedded electrodes is studied for high frequency and wide band SAW devices. Theoretical studies are performed to calculate the phase velocity and K 2 dispersion curves of the Rayleigh mode and its higher modes. The influences of various ScAlN film thickness and electrode thickness as well as different electrode materials on K 2 are also investigated. The maximum electromechanical Coupling Factor ( K 2 ) of surface acoustic wave (SAW) resonator based on such structure has been theoretically shown up to be 14.5%, which is about 2.5 times larger than the previously reported. Such an enhancement of K 2 makes this layered structure great potential application to ultrawide band SAW filters operating in 2–3 GHz range.
Guofeng Lou - One of the best experts on this subject based on the ideXlab platform.
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equivalent circuit model of low frequency magnetoelectric effect in disk type terfenol d pzt laminate composites considering a new interface Coupling Factor
Sensors, 2017Co-Authors: Guofeng LouAbstract:This paper describes the modeling of magnetoelectric (ME) effects for disk-type Terfenol-D (Tb0.3Dy0.7Fe1.92)/PZT (Pb(Zr,Ti)O3) laminate composite at low frequency by combining the advantages of the static elastic model and the equivalent circuit model, aiming at providing a guidance for the design and fabrication of the sensors based on magnetoelectric laminate composite. Considering that the strains of the magnetostrictive and piezoelectric layers are not equal in actual operating due to the epoxy resin adhesive bonding condition, the magnetostrictive and piezoelectric layers were first modeled through the equation of motion separately, and then coupled together with a new interface Coupling Factor kc, which physically reflects the strain transfer between the phases. Furthermore, a theoretical expression containing kc for the transverse ME voltage coefficient αv and the optimum thickness ratio noptim to which the maximum ME voltage coefficient corresponds were derived from the modified equivalent circuit of ME laminate, where the interface Coupling Factor acted as an ideal transformer. To explore the influence of mechanical load on the interface Coupling Factor kc, two sets of weights, i.e., 100 g and 500 g, were placed on the top of the ME laminates with the same thickness ratio n in the sample fabrication. A total of 22 T-T mode disk-type ME laminate samples with different configurations were fabricated. The interface Coupling Factors determined from the measured αv and the DC bias magnetic field Hbias were 0.11 for 500 g pre-mechanical load and 0.08 for 100 g pre-mechanical load. Furthermore, the measured optimum thickness ratios were 0.61 for kc = 0.11 and 0.56 for kc = 0.08. Both the theoretical ME voltage coefficient αv and optimum thickness ratio noptim containing kc agreed well with the measured data, verifying the reasonability and correctness for the introduction of kc in the modified equivalent circuit model.
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equivalent circuit model of low frequency magnetoelectric effect in disk type terfenol d pzt laminate composites considering a new interface Coupling Factor
Sensors, 2017Co-Authors: Guofeng Lou, Xinjie Yu, Shihua LuAbstract:This paper describes the modeling of magnetoelectric (ME) effects for disk-type Terfenol-D (Tb0.3Dy0.7Fe1.92)/PZT (Pb(Zr,Ti)O3) laminate composite at low frequency by combining the advantages of the static elastic model and the equivalent circuit model, aiming at providing a guidance for the design and fabrication of the sensors based on magnetoelectric laminate composite. Considering that the strains of the magnetostrictive and piezoelectric layers are not equal in actual operating due to the epoxy resin adhesive bonding condition, the magnetostrictive and piezoelectric layers were first modeled through the equation of motion separately, and then coupled together with a new interface Coupling Factor kc, which physically reflects the strain transfer between the phases. Furthermore, a theoretical expression containing kc for the transverse ME voltage coefficient αv and the optimum thickness ratio noptim to which the maximum ME voltage coefficient corresponds were derived from the modified equivalent circuit of ME laminate, where the interface Coupling Factor acted as an ideal transformer. To explore the influence of mechanical load on the interface Coupling Factor kc, two sets of weights, i.e., 100 g and 500 g, were placed on the top of the ME laminates with the same thickness ratio n in the sample fabrication. A total of 22 T-T mode disk-type ME laminate samples with different configurations were fabricated. The interface Coupling Factors determined from the measured αv and the DC bias magnetic field Hbias were 0.11 for 500 g pre-mechanical load and 0.08 for 100 g pre-mechanical load. Furthermore, the measured optimum thickness ratios were 0.61 for kc = 0.11 and 0.56 for kc = 0.08. Both the theoretical ME voltage coefficient αv and optimum thickness ratio noptim containing kc agreed well with the measured data, verifying the reasonability and correctness for the introduction of kc in the modified equivalent circuit model.
Bruce R Selman - One of the best experts on this subject based on the ideXlab platform.
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a role for the disulfide bond spacer region of the chlamydomonas reinhardtii Coupling Factor 1 gamma subunit in redox regulation of atp synthase
Journal of Bioenergetics and Biomembranes, 1996Co-Authors: Stuart A Ross, Michael X Zhang, Bruce R SelmanAbstract:Theγ-subunit of chloroplast Coupling Factor 1 contains a disulfide bond which is involved in the redox regulation of the enzyme. In all the sequenced plant γ-subunits this disulfide bond is separated by a five amino acid spacer region. To investigate the regulatory significance of this region genetic transformation experiments were performed withChlamydomonas reinhardtii. C. reinhardtii strainatpC1(nit 1-305, cw 15, mt−), which does not accumulate the CF1γ-subunit polypeptide, was independently transformed with two constructs, each bearing mutations within the disulfide bond spacer region between Cys198 and Cys204 of theγ-subunit. Successful complementation was confirmed by phenotypic selection. Northern blot analysis, and reverse transcription polymerase chain reaction. Whereas wild-type thylakoid membrane particles catalyzein vitro, PMS-dependent photophosphorylation that is stimulated 2-fold by the addition of DTT, similar particles from each of the mutant strains exhibit rates of ATP synthesis that are independent of DTT. Consistent with these results, wild-type CF1 ATPase activity is stimulated by DTT which is in contrast to the ATPase activities of both the mutant strains which are independent of DTT addition. These results suggest a role for the γ-subunit disulfide bond spacer region in the redox regulation of chloroplast ATP synthase.
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role of the chlamydomonas reinhardtii Coupling Factor 1 γ subunit cysteine bridge in the regulation of atp synthase
Journal of Biological Chemistry, 1995Co-Authors: Stuart A Ross, Michael X Zhang, Bruce R SelmanAbstract:Abstract The γ-subunit of Coupling Factor 1 (CF1) contains a cysteine bridge that is thought to be involved in the redox control of enzymatic activity. In order to test the regulatory significance of this disulfide bond, genetic transformation experiments with Chlamydomonas reinhardtii were performed. C. reinhardtii strain atpC1 (nit1-305, cw 15, mt−), which is null for the γ-subunit, was transformed and complemented with γ-subunit constructs containing amino acid substitutions localized to the cysteine bridge between Cys198and Cys204. Successful complementation was confirmed by phenotypic selection, Northern blot analysis, reverse transcription polymerase chain reaction, and cDNA sequencing. CF1ATPase activities of the soluble enzymes were measured in the presence and absence of dithiothreitol (DTT). Mutant CF1enzymes showed no effect of DTT although increased activity was observed for the wild-type enzyme. In vitro, phenazine methosulfate-dependent photophosphorylation assays revealed that wild-type CF1exhibits a 2-fold stimulation in the presence of 25 mM DTT, whereas each of the mutant enzymes has activities that are DTT-independent. Growth measurements indicated that despite the absence of a regulatory disulfide/dithiol, the mutant strains grew with the same kinetics as wild type. This study provides evidence to illustrate the involvement of the γ-subunit in the redox regulation of ATP synthesis in vivo. This work is also the first demonstration in C. reinhardtii of stable nuclear transformation using mutated genes to complement a known defect.
