The Experts below are selected from a list of 1659 Experts worldwide ranked by ideXlab platform

Xinwu Cao - One of the best experts on this subject based on the ideXlab platform.

  • the Launching Condition of a jet driven by the magnetic field and radiation pressure of an accretion disc
    arXiv: High Energy Astrophysical Phenomena, 2012
    Co-Authors: Xinwu Cao
    Abstract:

    We find that the cold gas can be magnetically launched from the disc surface with the help of the radiation pressure if the angular velocity of the radiation pressure dominated accretion disc is greater than a critical value, which decreases with increasing the disc thickness H/R (radiation pressure). This indicates the force exerted by the radiation from the disc indeed helps Launching the outflow. The rotational velocity of the gas in the disc depends on the strength of the magnetic field threading the disc and the inclination B_z/B_r of the field line at the disc surface. The Launching Condition for the cold gas at the disc surface sets an upper limit on the magnetic field strength, which is a function of the field line inclination B_z/B_r and the disc thickness H/R. This implies a more strict constraint on the maximal jet power can be extracted from a radiation pressure dominated accretion disc than that derived conventionally on the equipartition assumption.

  • the Launching Condition of a jet driven by the magnetic field and radiation pressure of an accretion disc
    Monthly Notices of the Royal Astronomical Society, 2012
    Co-Authors: Xinwu Cao
    Abstract:

    We find that cold gas can be magnetically launched from the surface of a disc with the help of the radiation pressure, if the angular velocity of the radiation-pressure-dominated accretion disc is greater than a critical value, which decreases when increasing the disc thickness Hd/R (radiation pressure). This indicates that the force exerted by the radiation from the disc does help to launch the outflow. The rotational velocity of the gas in the disc depends on the strength of the magnetic field threading the disc and the inclination ?0 (?0 = Bz/Br) of the field line at the disc's surface. The Launching Condition for cold gas at the disc's surface sets an upper limit on the magnetic field strength, which is a function of the field-line inclination ?0 and the disc thickness Hd/R. This implies that a more strict constraint on the maximal jet power can be extracted from a radiation-pressure-dominated accretion disc than that derived conventionally on the equipartition assumption.

C.d. Singh - One of the best experts on this subject based on the ideXlab platform.

  • critical micelle concentration cmc measurements using u shaped fiber optic probes
    Sensors and Actuators B-chemical, 2003
    Co-Authors: C.d. Singh, Y. Shibata, Masami Ogita
    Abstract:

    In this paper a simple U-shape optical fiber probe, for determination of critical micelle concentration (CMC), using evanescent adsorption effect has been described. Fabrication and characterization of the U-shape fiber optic probe has been discussed. The U-shaped is used to increase the evanescent field and hence it interaction with the sample solutions consisting mainly of sodium dodecylbenzenesulfonate. The effect of light Launching Condition and bending radius of the probe on the critical micelle concentration is studied. It has been shown that, for a given value of the sample solution, decrease the bending radius of the U-shape increases the sensitivity of the sensor and improve the finding of critical micelle concentration point.

  • Effect of Launching Condition in response time analysis for few selected tapered porous clad optical fiber gas sensors
    Optical and Quantum Electronics, 2001
    Co-Authors: C.d. Singh, Karan Singh
    Abstract:

    In this paper, the effect of Launching Condition of light and the geometry of the sensing region in the case of detection of gases using attenuated total internal reflection (ATR) technique in multimode step index tapered fiber has been described. Using ray approach the response time of the sensor in case of parabolic, linear and exponential-linear tapered optical fiber have been carried out. It has been shown that Launching Condition and geometry of the sensing region effect the sensitivity of the sensor. Out of three designs the sensor having exponential-linear tapered with selected ray Launching has maximum sensitivity and low response time of the sensor.

Schmauss Bernhard - One of the best experts on this subject based on the ideXlab platform.

  • Novel Model for the Angle and Skewness Dependent Transmission Behavior of Step-Index Polymer Optical Fiber
    'MDPI AG', 2018
    Co-Authors: Becker Thomas, Engelbrecht Rainer, Schmauss Bernhard
    Abstract:

    Step-index polymer optical fibers (SI-POFs) are deployed in both sensing and data transmission systems. The optical transmission behavior of these fibers is complex and affected by intrinsic influences like modal dispersion, scattering and attenuation as well as extrinsic influences like the Launching Condition and the angular sensitivity of the receiver. Since a proper modeling of the transmission behavior is important in order to evaluate the suitability of the fiber for a specific application, we present a novel model for step-index multi-mode fibers (SI-MMFs) which considers all the previously mentioned impacts. Furthermore, the model differentiates scattering and attenuation for propagating rays not only by their propagating angle θz but also by the skewness θϕ . It is therefore possible to distinguish between guided, tunneling and refracted modes. The model uses scatter and attenuation data from previously published measurements of an SI-POF and computes the impulse response of the transmission system which is transferred to the frequency domain to derive the amplitude and phase response. A possible application for SI-POF is the length or strain measurement of the fiber by measuring the phase of a harmonically modulated signal. These sensors rely on a linear relation between the length of the fiber and the phase of the modulated signal. We demonstrate the application of the model by simulating the length measurement error that occurs for these sensors by obtaining the phase response for the corresponding optical transmission system. Furthermore, we will demonstrate the flexibility of the model by varying several influences including the excitation of different mode categories and evaluate the impact on the measurement error. Finally, we compare the simulated length error derived from the model to real data obtained from a cutback measurement. An implementation of the model, which was used for all simulations in this paper, is publicly available

Bernhard Schmauss - One of the best experts on this subject based on the ideXlab platform.

  • Novel Model for the Angle and Skewness Dependent Transmission Behavior of Step-Index Polymer Optical Fiber
    'MDPI AG', 2018
    Co-Authors: Thomas Becker, Rainer Engelbrecht, Bernhard Schmauss
    Abstract:

    Step-index polymer optical fibers (SI-POFs) are deployed in both sensing and data transmission systems. The optical transmission behavior of these fibers is complex and affected by intrinsic influences like modal dispersion, scattering and attenuation as well as extrinsic influences like the Launching Condition and the angular sensitivity of the receiver. Since a proper modeling of the transmission behavior is important in order to evaluate the suitability of the fiber for a specific application, we present a novel model for step-index multi-mode fibers (SI-MMFs) which considers all the previously mentioned impacts. Furthermore, the model differentiates scattering and attenuation for propagating rays not only by their propagating angle θ z but also by the skewness θ ϕ . It is therefore possible to distinguish between guided, tunneling and refracted modes. The model uses scatter and attenuation data from previously published measurements of an SI-POF and computes the impulse response of the transmission system which is transferred to the frequency domain to derive the amplitude and phase response. A possible application for SI-POF is the length or strain measurement of the fiber by measuring the phase of a harmonically modulated signal. These sensors rely on a linear relation between the length of the fiber and the phase of the modulated signal. We demonstrate the application of the model by simulating the length measurement error that occurs for these sensors by obtaining the phase response for the corresponding optical transmission system. Furthermore, we will demonstrate the flexibility of the model by varying several influences including the excitation of different mode categories and evaluate the impact on the measurement error. Finally, we compare the simulated length error derived from the model to real data obtained from a cutback measurement. An implementation of the model, which was used for all simulations in this paper, is publicly available

Jerzy Siuzdak - One of the best experts on this subject based on the ideXlab platform.

  • Influence of modal filtering on the bandwidth of multimode optical fibers
    Optica Applicata, 2007
    Co-Authors: Grzegorz Stępniak, Jerzy Siuzdak
    Abstract:

    The multimode (MM) optical fiber maximum operational range is defined by the fiber bandwidth (related to the intermodal dispersion) rather than by the fiber attenuation. The relationship between the modal bandwidth of the fiber, the Launching Condition and mode coupling is fairly complicated. There is presented a theoretical study on the modal bandwidth of the multimode fiber. The theory is based on a numerical solution of the coupled mode diffusion equation that allows the bandwidth of the MM optical fiber to be calculated. It is shown that appropriate modal filtering at the receiver side of the fiber link increases the link bandwidth.