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Cheng-fu Yang - One of the best experts on this subject based on the ideXlab platform.

  • Influences of Different Calcining Method on the Characteristics of 0.65(K0.5Bi0.5TiO3)–0.35BaTiO3 Ceramics
    Advanced Materials Research, 2014
    Co-Authors: Yuan Tai Hsieh, Cheng-fu Yang, Chien-chen Diao, Ying Hsun Lin
    Abstract:

    0.65(K0.5Bi0.5)TiO3–0.35BaTiO3 (0.65 KBT-0.35 BT3) ceramic was synthesized using a conventional calcination process (CC-process), and using a two-step calcination process that combined hydrothermal and CC processes (HT-CC-process). The effects of these two different calcination processes on the physical and dielectric properties of 0.65 KBT-0.35 BT3 ceramics were recorded and analyzed. When the CC-process was used, secondary phases—namely, BaBi4Ti4O15, K2TiO3, and K4Ti3O8—were observed in the XRD patterns of 0.65 KBT-0.35 BT3 ceramics. When the HT-CC-process was used, only the (K0.5Bi0.5)TiO3 (or (K0.5Bi0.5, Ba)TiO3) phase was observed in the XRD patterns, with no secondary phases. Due to the secondary phases, the CC-process 0.65 KBT-0.35 BT3 ceramic had lower dielectric peaks and broader temperature-dielectric Constant Curve than the 0.65 KBT-0.35 BT3 ceramic synthesized using the HT-CC-process.

  • Effects of NaNbO3 concentration on the relaxor and dielectric properties of the lead-free (Na0.5Bi0.5)TiO3 ceramics
    CrystEngComm, 2013
    Co-Authors: Cheng-fu Yang
    Abstract:

    In this study, different NaNbO3 concentrations (abbreviated as NN) were added into lead-free (Na0.5Bi0.5)TiO3 (NBT) to form the (1 − x) NBT–x NN ceramics by using the solid-state reaction method, where x was equal to 0.1, 0.2, 0.3, and 0.4, respectively. The dielectric Constant–temperature (er–T) Curves revealed that the solid solution underwent two phase transitions, from ferroelectric to anti-ferroelectric phases and from anti-ferroelectric to paraelectric phases. The er–T Curves also showed that the depolarization temperature (Td) was shifted to lower value, the Curie temperature (Tc) was shifted to higher value, and the maximum dielectric Constant decreased with increasing NN concentration. The Curie–Weiss law and the modified Curie–Weiss law were used to discuss the phase transitions of the (1 − x) NBT–x NN ceramics. Dielectric study revealed that the behavior of the relaxor-type ferroelectric ceramics became more obvious as increasing NN composition was added into the NBT ceramic. As observed from the er–T Curves, the 0.8 NBT–0.2 NN ceramic revealed a higher dielectric Constant and more stable dielectric Constant Curve.

Somenath Mukherjee - One of the best experts on this subject based on the ideXlab platform.

  • Vibration analysis of multi-supported Curved panel using the periodic structure approach
    International Journal of Mechanical Sciences, 2002
    Co-Authors: Chitaranjan Pany, S. Parthan, Somenath Mukherjee
    Abstract:

    This papers deals with the radial vibration of a row of cylindrical panels of finite length using the concept of wave propagation in periodic structures. For this study, the structure is considered as an assemblage of a number of identical cylindrically Curved panels each of which will be referred to as a periodic element. For a given geometry dispersion Curves of the propagation Constant versus (non-dimensional) natural frequency have been drawn corresponding to the circumferential wave propagation. New conclusions that have emerged from this study are as follows. It is shown that by a proper choice of the periodic element the bounding frequencies and the corresponding modes in all the propagation bands can be determined. These have been shown to correspond to a single Curved panel with all its edges simply supported. It is noted that there are no attenuation gaps in the entire frequency spectrum beyond the lowest bounding frequency. This is a unique feature of circumferential wave propagation around circular cylindrical shells and panels, as opposed to the wave propagation of periodically supported beams and rectangular panels without curvature. The natural frequency corresponding to every circumferential mode of the complete shell has been identified on the propagation Constant Curve. It has been observed that the natural frequencies of a cylindrically Curved panel of a given curvature and length but of different circumferential arc length (corresponding to different angles subtended at the centre of any circular cross-section) may also be identified on the same propagation Constant Curve. Finally, it is shown that the same propagation Constant Curve may also be used to determine all the natural frequencies of a finite row of Curved panels with the extreme edges simply supported. Wherever possible the numerical results have been compared with those obtained independently from finite element analysis and/or results available in the literature. Flutter analysis of multi-span Curved panels using a wave approach is the ultimate objective of this work.

Kee Hoon Kim - One of the best experts on this subject based on the ideXlab platform.

  • Low-magnetic-field control of dielectric Constant at room temperature realized in Ba0.5Sr1.5Zn2Fe12O22
    New Journal of Physics, 2009
    Co-Authors: Yisheng Chai, Sae Hwan Chun, S. Y. Haam, Ingyu Kim, Kee Hoon Kim
    Abstract:

    We show that room temperature resistivity of Ba0.5Sr1.5Zn2Fe12O22 single crystals increases by more than three orders of magnitude upon being subjected to optimized heat treatments. The increase in the resistivity allows the determination of magnetic field (H)-induced ferroelectric phase boundaries up to 310 K through the measurements of dielectric Constant at a frequency of 10 MHz. Between 280 and 310 K, the dielectric Constant Curve shows a peak centered at zero magnetic field and thereafter decreases monotonically up to 0.1 T, exhibiting a magnetodielectric effect of 1.1%. This effect is ascribed to the realization of magnetic field-induced ferroelectricity at an H value of less than 0.1 T near room temperature. Comparison between electric and magnetic phase diagrams in wide temperature- and field-windows suggests that the magnetic field for inducing ferroelectricity has decreased near its helical spin ordering temperature around 315 K due to the reduction of spin anisotropy in Ba0.5Sr1.5Zn2Fe12O22.

Jan P. Roos - One of the best experts on this subject based on the ideXlab platform.

  • Analysis of time-activity Curves related to myocardial metabolism. The case of 123I-heptadecanoic acid.
    Nuclear Medicine Communications, 1991
    Co-Authors: Machiel J. Van Eenige, Frans C. Visser, G. Westera, A. Van Lingen, A. J. P. Karreman, P. D. Bezemer, Jan P. Roos
    Abstract:

    Time-activity Curves are frequently used in the external assessment of the kinetics of radiolabelled non-esterified fatty acids. Analysis of time-activity Curves is accomplished by fitting an analytical Curve through the data points of the time-activity Curve, resulting in two or more parameters of the Curve fit. Before interpreting the results of Curve fitting, the precision of each of the parameters has to be determined. In the present study the precision of the parameters of monoexponential plus Constant Curve fit of time-activity Curves after administration of 123I-heptadecanoic acid was assessed for an acquisition time of 75 min. Two parameters were used, the T1/2 of the monoexponential and the ratio A/A+C, where A is the amplitude of the monoexponential and C the Constant. A model study was used to assess the precision of the parameters of Curve fitting. The precision of the parameters was calculated for wide ranges of the T1/2 (0-60 min), A/A+C (0-100%) and the noise content of the time-activity Curve. The results are presented as the 10th and 90th percentiles.

David Wolfenson - One of the best experts on this subject based on the ideXlab platform.

  • Two methods of inducing low plasma progesterone concentrations have different effects on dominant follicles in cows.
    Journal of dairy science, 2000
    Co-Authors: A. Shaham-albalancy, Miriam Rosenberg, Y. Folman, Y. Graber, R Meidan, David Wolfenson
    Abstract:

    Abstract The effects of two methods of inducing low progesterone concentrations on the shape of the plasma progesterone Curve and on follicular characteristics in lactating cows were studied. A low ascending progesterone Curve was elicited by three PGF 2α injections on d 3 to 4 of the estrous cycle; a low Constant Curve by induction of corpus luteum regression on d 6 and insertion of two progesterone-containing intravaginal devices from d 6 to 15 of the cycle. Plasma progesterone concentration was highest in the untreated control group, intermediate in low ascending group, and lowest in the low Constant group. On d 15, both control and low ascending groups had one large healthy and one large atretic follicle, suggesting a turnover of follicular waves; in the low Constant group, the presence of only one very large healthy follicle indicated follicular persistence. Estradiol concentration in the follicular fluid and its production by granulosa cells were highest in the low Constant, intermediate in the low ascending, and lowest in the control group. Androstenedione concentration in the follicular fluid and its production by theca cells were higher in the low Constant than in the low ascending and control groups. The results indicate that the low ascending progesterone Curve affected follicular development and steroidogenesis differently from the low Constant Curve. We suggest that the low ascending Curve mimics the effects of naturally occurring low plasma progesterone concentrations better, and it might, therefore, be used as a model for studying the effects of low plasma progesterone on fertility.