The Experts below are selected from a list of 4290 Experts worldwide ranked by ideXlab platform

Han Lan Ke - One of the best experts on this subject based on the ideXlab platform.

  • Study on the Photosynthetic Efficiency of the Osmanthus fragrans Leaves by Using Photo-Acoustic Tomography Spectroscopy Technology
    Advanced Materials Research, 2020
    Co-Authors: Han Lan Ke
    Abstract:

    By using a new kind of single-beam normalized photo-Acoustic Tomography spectroscopy (PAS-CT) technology with non-damage detection, the photo-Acoustic Tomography spectroscopy, optical absorption properties and photosynthetic pigment content of the green and yellow leaves of Osmanthus fragrans were studied. The results show that: photo-Acoustic Tomography spectroscopy could be obtained from different chopping frequency and different sample position. The more photosynthetic pigment content the leaves of Osmanthus fragrans contains, the bigger optical absorption coefficient and the higher photosynthetic efficiency they have. In the research, we could find that the photosynthetic pigment content of the green leaves of Osmanthus fragrans is higher than that of the yellow ones. As a result, the optical absorption coefficient and the photosynthetic efficiency of the green ones are higher than the yellow ones. The photo-Acoustic Tomography spectroscopy technology could be a kind of non-damage detection to confirm the growth of trees.

  • Study on the Photosynthetic Efficiency of the Cinnamomum camphora Leaves by Using Photo-Acoustic Tomography Spectroscopy Technology
    Advanced Materials Research, 2012
    Co-Authors: Han Lan Ke, Ting Yang, Dong Yu Li, Dao Qing Zhang, Xiao Qiong Feng
    Abstract:

    By using a new kind of single-beam normalized photo-Acoustic Tomography spectroscopy (PAS-CT) technology with non-damage detection, the photo-Acoustic Tomography spectroscopy, optical absorption properties and photosynthetic pigment content of the green and yellow leaves of Cinnamomum camphora were studied. The results show that: photo-Acoustic Tomography spectroscopy could be obtained from different chopping frequency and different sample position. The more photosynthetic pigment content the leaves of Cinnamomum camphora contains, the bigger optical absorption coefficient and the higher photosynthetic efficiency they have. In the research, we could find that the photosynthetic pigment content of the green leaves of Cinnamomum camphora is higher than that of the red ones. As a result, the optical absorption coefficient and the photosynthetic efficiency of the green ones are higher than the red ones. The photo-Acoustic Tomography spectroscopy technology could be a kind of non-damage detection to confirm the growth of trees.

  • Study on the Photosynthetic Efficiency of the Michelia alba Leaves by Using Photo-Acoustic Tomography Spectroscopy Technology
    Advanced Materials Research, 2012
    Co-Authors: Xiao Qiong Feng, Dao Qing Zhang, Ting Yang, Han Lan Ke
    Abstract:

    By using a new kind of single-beam normalized photo-Acoustic Tomography spectroscopy (PAS-CT) technology with non-damage detection, the photo-Acoustic Tomography spectroscopy, optical absorption properties and photosynthetic pigment content of the green and yellow leaves of Michelia alba were studied. The results show that: photo-Acoustic Tomography spectroscopy could be obtained from different chopping frequency and different sample position. The more photosynthetic pigment content the leaves of Michelia alba contains, the bigger optical absorption coefficient and the higher photosynthetic efficiency they have. In the research, we could find that the photosynthetic pigment content of the green leaves of Michelia alba is higher than that of the yellow ones. As a result, the optical absorption coefficient and the photosynthetic efficiency of the green ones are higher than the yellow ones. The photo-Acoustic Tomography spectroscopy technology could be a kind of non-damage detection to confirm the growth of trees.

Astrid Ziemann - One of the best experts on this subject based on the ideXlab platform.

  • Acoustic Tomography of the Atmosphere Using Unscented Kalman Filter
    IEEE Transactions on Geoscience and Remote Sensing, 2014
    Co-Authors: Soheil Kolouri, Mahmood R. Azimi-sadjadi, Astrid Ziemann
    Abstract:

    Acoustic travel-time Tomography of the atmosphere is a nonlinear inverse problem which attempts to reconstruct temperature and wind velocity fields in the atmospheric surface layer using the dependence of sound speed on temperature and wind velocity fields along the propagation path. This paper presents a new statistical-based Acoustic travel-time Tomography algorithm based on unscented Kalman filter (UKF) which is capable of reconstructing and tracking temperature and wind velocity fields (state variables) within a specified investigation area. The method exploits an iterative ray-tracing algorithm to handle situations when straight-ray assumption no longer holds. The observations used in the UKF process consists of the Acoustic travel times computed for every pair of transmitter/reciever nodes deployed in the investigation area. A first-order spatial-temporal autoregressive model is used to account for state evolution in the UKF. To evaluate the performance of the UKF-based Acoustic Tomography method, 2-D fractal Brownian motion is used to generate synthetic temperature and wind velocity fields with spatial and temporal resolution of 1 m and 12 s, respectively. The UKF-based Acoustic Tomography algorithm is then compared to the well-known time-dependent stochastic inversion method. The results reveal the effectiveness of the proposed method for accurate and fast reconstruction of temperature and wind velocity fields.

  • recent progress in Acoustic Tomography of the atmosphere
    IOP Conference Series: Earth and Environmental Science, 2008
    Co-Authors: D.k. Wilson, Vladimir E. Ostashev, Sergey N Vecherin, Astrid Ziemann, George H Goedecke
    Abstract:

    Acoustic Tomography of the atmospheric surface layer is based on measurements of travel times of sound propagation among different pairs of sources and receivers usually located several meters above the ground on a horizontal scale of about 100 m. The measured travel times are used as input data in an inverse algorithm for reconstruction of temperature and wind velocity fields. Improved knowledge of these fields is important in boundary layer meteorology, theories of turbulence, and studies of electromagnetic and Acoustic wave propagation in the atmosphere. In this paper, a short overview and current status of Acoustic travel-time Tomography of the atmosphere are presented. A brief description of a 3D array for Acoustic Tomography of the atmosphere which is being built at the Boulder Atmospheric Observatory is given. Furthermore, different inverse algorithms for reconstruction of temperature and velocity fields are discussed, including stochastic inversion and a recently developed time-dependent stochastic inversion. The latter inverse algorithm was used to reconstruct temperature and wind velocity fields in Acoustic Tomography experiments. Examples of the reconstructed fields are presented and discussed.

  • Acoustic Tomography inside the atmospheric boundary layer
    Physics and Chemistry of The Earth Part B-hydrology Oceans and Atmosphere, 1999
    Co-Authors: Klaus Arnold, Astrid Ziemann, Armin Raabe
    Abstract:

    Abstract Acoustic Tomography is presented as a technique for remote monitoring of meteorological quantities. This method and a special algorithm of analysis can directly produce area averaged values of meteorological parameters. As a result, consistent data will be delivered for validation of numerical atmospheric micro-scale models. Such a measuring system can complement conventional point measurements over different surfaces. The procedure of Acoustic Tomography uses the horizontal propagation of sound waves in the atmospheric surface layer. The state of the crossed atmosphere can be estimated from measurements of travel time of Acoustic signals between sources and receivers on different points in a tomographic array. Derivation of area averaged values of the sound speed and furthermore of air temperature results from the inversion of travel time values for all possible Acoustic paths. Thereby, the applied straight-ray two-dimensional Tomography model is characterised as a method with small computational equirements and simple handling, especially, for online work.

  • Acoustic Tomography in the atmospheric surface layer
    Annales Geophysicae, 1999
    Co-Authors: Astrid Ziemann, Klaus Arnold, Armin Raabe
    Abstract:

    Abstract. Acoustic Tomography is presented as a technique for remote monitoring of meteorological quantities. This method and a special algorithm of analysis can directly produce area-averaged values of meteorological parameters. As a result consistent data will be obtained for validation of numerical atmospheric micro-scale models. Such a measuring system can complement conventional point measurements over different surfaces. The procedure of Acoustic Tomography uses the horizontal propagation of sound waves in the atmospheric surface layer. Therefore, to provide a general overview of sound propagation under various atmospheric conditions a two-dimensional ray-tracing model according to a modified version of Snell's law is used. The state of the crossed atmosphere can be estimated from measurements of Acoustic travel time between sources and receivers at different points. Derivation of area-averaged values of the sound speed and furthermore of air temperature results from the inversion of travel time values for all Acoustic paths. Thereby, the applied straight ray two-dimensional tomographic model using SIRT (simultaneous iterative reconstruction technique) is characterised as a method with small computational requirements, satisfactory convergence and stability properties as well as simple handling, especially, during online evaluation. Key words. Meteorology and atmospheric dynamics (turbulence; instruments and techniques).

Xiao Qiong Feng - One of the best experts on this subject based on the ideXlab platform.

  • Study on the Photosynthetic Efficiency of the Cinnamomum camphora Leaves by Using Photo-Acoustic Tomography Spectroscopy Technology
    Advanced Materials Research, 2012
    Co-Authors: Han Lan Ke, Ting Yang, Dong Yu Li, Dao Qing Zhang, Xiao Qiong Feng
    Abstract:

    By using a new kind of single-beam normalized photo-Acoustic Tomography spectroscopy (PAS-CT) technology with non-damage detection, the photo-Acoustic Tomography spectroscopy, optical absorption properties and photosynthetic pigment content of the green and yellow leaves of Cinnamomum camphora were studied. The results show that: photo-Acoustic Tomography spectroscopy could be obtained from different chopping frequency and different sample position. The more photosynthetic pigment content the leaves of Cinnamomum camphora contains, the bigger optical absorption coefficient and the higher photosynthetic efficiency they have. In the research, we could find that the photosynthetic pigment content of the green leaves of Cinnamomum camphora is higher than that of the red ones. As a result, the optical absorption coefficient and the photosynthetic efficiency of the green ones are higher than the red ones. The photo-Acoustic Tomography spectroscopy technology could be a kind of non-damage detection to confirm the growth of trees.

  • Study on the Photosynthetic Efficiency of the Michelia alba Leaves by Using Photo-Acoustic Tomography Spectroscopy Technology
    Advanced Materials Research, 2012
    Co-Authors: Xiao Qiong Feng, Dao Qing Zhang, Ting Yang, Han Lan Ke
    Abstract:

    By using a new kind of single-beam normalized photo-Acoustic Tomography spectroscopy (PAS-CT) technology with non-damage detection, the photo-Acoustic Tomography spectroscopy, optical absorption properties and photosynthetic pigment content of the green and yellow leaves of Michelia alba were studied. The results show that: photo-Acoustic Tomography spectroscopy could be obtained from different chopping frequency and different sample position. The more photosynthetic pigment content the leaves of Michelia alba contains, the bigger optical absorption coefficient and the higher photosynthetic efficiency they have. In the research, we could find that the photosynthetic pigment content of the green leaves of Michelia alba is higher than that of the yellow ones. As a result, the optical absorption coefficient and the photosynthetic efficiency of the green ones are higher than the yellow ones. The photo-Acoustic Tomography spectroscopy technology could be a kind of non-damage detection to confirm the growth of trees.

Noriaki Gohda - One of the best experts on this subject based on the ideXlab platform.

  • Vertical underwater Acoustic Tomography in an experimental basin
    Journal of the Acoustical Society of America, 2017
    Co-Authors: Guangming Li, David Ingram, Arata Kaneko, Minmo Chen, Noriaki Gohda, Nick Polydorides
    Abstract:

    Ocean Acoustic Tomography is well developed for monitoring environmental parameter changing for mesoscale ocean distribution. Small scale underwater Acoustic Tomography could be used for flow profile mapping in experimental tank. Vertical Acoustical Tomography analyse is a key aspect for 3D mapping of flow current profile. This article investigates vertical underwater Acoustic Tomography in a circular multidirectional wave/current basin. Two modified coastal Acoustic Tomography (CAT) systems were deployed in the 25 m diameter circular basin. High frequency (50 kHz) M-sequence signal was transmitted reciprocally for time of flight. The 2 m depth water column was divided into 5 layers for layered analysis. Multipath arrivals reflected by surface and bottom were distinguished by ray tracing. The 0.8 m/s straight flow was generated along the sound propagation path. Vertical layered current velocity was analyzed by solving inverse problem. The study suggest that vertical Acoustic Tomography could be used in th...

  • Recent progress in coastal Acoustic Tomography
    Journal of the Acoustical Society of America, 2016
    Co-Authors: Arata Kaneko, Fadli Syamsudin, Yudi Adityawarman, Hong Zheng, Chen-fen Huang, Naokazu Taniguchi, Noriaki Gohda
    Abstract:

    Coastal Acoustic Tomography (CAT) which was proposed by Hiroshima University in 1990s as a shallow-sea application of ocean Acoustic Tomography (OAT) is developed as a mirror-type CAT (MCAT) for measuring deep strait throughflows in Indonesian archipelago seas in real time. MCAT system is composed of a land station (M0) connected to a 100 m submarine cable edged by a 5 kHz subsurface transceiver and triangular-arrayed bottom-moored stations (M1, M2, and M3). Reciprocal data are first obtained among three station pairs (M1M2, M2M3, and M3M1). Data received at M1 from M2 and M3 are transferred to the land station (M0) by the first mirror reflection, resulting in travel time summations (t21 + t10, t31 + t10) (t21: travel time from M2 to M1). Data obtained at the offshore stations M2 and M3 are transferred to the nearshore station M1 by the first mirror reflection, resulting in travel time summations (t12 + t21, t13 + t31, t23 + t31, and t32 + t21). All the first mirror data at M1 are also transferred to M0 b...

  • The application of coastal Acoustic Tomography to a large experimental wave/current basin
    Journal of the Acoustical Society of America, 2016
    Co-Authors: Guangming Li, David Ingram, Arata Kaneko, Noriaki Gohda, Nick Polydorides
    Abstract:

    This article describes the use of Acoustic Tomography to characterize the flow pattern in the Flowave basin. Flowave is a unique circular wave/current basin, 2 m deep and 25 m in diameter. Current can be created in any direction at speed of up to 1.2 ms.-1. Two coastal Acoustic Tomography (CAT) stations were used operating at 50 kHz with a M- sequence signal. By combining three different pairs of station positions and seven current directions a network of seven CAT stations has been emulated. Throughout the test, a current speed of 0.8 ms-1 was used. Using the inverse Fourier method, a velocity profile has been obtained. During the experiment, a Nortek vectrino velocimetry was placed between the stations. This paper will present the comparison between the vectrino and CAT measurement.

  • Current structure measurements by the coastal Acoustic Tomography
    Journal of the Acoustical Society of America, 2006
    Co-Authors: Arata Kaneko, Noriaki Gohda, Hong Zheng, Keisuke Yamaguchi, Yoshio Takasugi
    Abstract:

    The coastal Acoustic Tomography (CAT), coastal‐sea application of deep‐sea Acoustic Tomography (Munk and Wunsch, 1978), is proposed as an advanced technology to map current structures in the coastal sea. A sequence of successful experiments was recently carried out in the coastal seas with various oceanographic conditions around Japan (Yamaguchi et al., 2005; Kaneko et al., 2005; Lin et al., 2005). In the Tokyo Bay experiment of November 2002, the 2‐D tidal currents inducing a clockwise residual circulation were mapped by eight CAT systems, located at both the eastern and western coasts of the bay. The vortex‐embedded tidal currents with a maximum velocity of 5 ms−1 were targets in the Kanmon Strait experiment of March 2003. In the Hiroshima Bay experiment of September 2003, the stratified sea was shifted to the homogenized sea after the passage of a typhoon. The transition of tidal current structures before and after the typhoon was well measured by seven CAT systems, located at the northern coast and on...

  • A multistation coastal Acoustic Tomography system with coherent operation
    Journal of the Acoustical Society of America, 2006
    Co-Authors: Hong Zheng, Arata Kaneko, Noriaki Gohda
    Abstract:

    A multistation coastal ocean Acoustic Tomography (CAT) system with coherent operation has been developed and applied to field experiments over ten times in the last 8 years. The system is designed to measure both temperature and current velocity fields in the coastal ocean. As is well known, an ocean Acoustic Tomography is generally based on travel time measurements. In the CAT system, the clock accuracy for travel time measurement is most important to realize coherent transmission from multistations and to measure especially current velocity. For highly accurate coherent transmission from multistations, each station is equipped with a timing module synchronized by the clock signals of global positioning system (GPS). As a result, time error is maintained less than 0.1 μs. In the sound transmission from multistations, the code division multiple access (CDMA) and spread spectrum technology are applied. The coded signals also improved remarkably the signal‐to‐noise ratio of the CAT system. With detecting no...

Vladimir E. Ostashev - One of the best experts on this subject based on the ideXlab platform.

  • Acoustic Tomography of the Atmospheric Surface Layer
    2014
    Co-Authors: Vladimir E. Ostashev, Alfred J. Bedard
    Abstract:

    Abstract : Acoustic Tomography of the atmospheric surface layer (ASL) is based on the measurements of the travel times of sound propagation between speakers and microphone which constitute a Tomography array. The travel times are then used as input parameters in the inverse algorithms for reconstruction of temperature and wind velocity fields. In this project, we have continued our long-term theoretical and experimental studies of Acoustic Tomography of the ASL. The inverse algorithms for the tomographic reconstruction were modified and extended. In particular, two algorithms were developed for the assessment and elimination of the systematic errors in the travel-time measurements. The algorithms were applied for the reconstruction of the turbulence fields from the travel times obtained with the Acoustic Tomography array at the Boulder Atmospheric Observatory (BAO). The BAO Tomography array was also used for measurements of the area-averaged values of temperature, wind velocity, and horizontal heat flux. To improve a spatial resolution of an ultrasonic anemometer, it was suggested that one consider it is as a small Acoustic Tomography array and apply appropriate inverse methods for reconstruction of temperature and velocity. The upgrades of the BAO Acoustic Tomography array were completed and new experiments were carried out.

  • Acoustic Tomography of the atmosphere at the Boulder Atmospheric Observatory.
    Journal of the Acoustical Society of America, 2008
    Co-Authors: Vladimir E. Ostashev, Alfred J. Bedard, Sergey N Vecherin, D.k. Wilson
    Abstract:

    An array for Acoustic Tomography of the atmosphere has been built at the NOAA Boulder Atmospheric Observatory. In this paper, a short description of the array and some Acoustic Tomography results are presented. The array consists of three speaker and five microphone towers located along the perimeter of a square with a side length of 80 m. The towers are 9.1 m high. The speakers and microphones can be located at different (multiple) levels on the towers to do three‐dimensional Tomography. The transducers are connected via cables with the central command and data acquisition computer. The array enables measurements of travel times of sound propagation between different pairs of speakers and microphones. The measurements are done repeatedly within a short time interval so that the information about the temporal change in the travel times can be employed in tomographic reconstruction. Then, these travel times are used as input data in a time‐dependent stochastic inversion for reconstruction of temperature an...

  • recent progress in Acoustic Tomography of the atmosphere
    IOP Conference Series: Earth and Environmental Science, 2008
    Co-Authors: D.k. Wilson, Vladimir E. Ostashev, Sergey N Vecherin, Astrid Ziemann, George H Goedecke
    Abstract:

    Acoustic Tomography of the atmospheric surface layer is based on measurements of travel times of sound propagation among different pairs of sources and receivers usually located several meters above the ground on a horizontal scale of about 100 m. The measured travel times are used as input data in an inverse algorithm for reconstruction of temperature and wind velocity fields. Improved knowledge of these fields is important in boundary layer meteorology, theories of turbulence, and studies of electromagnetic and Acoustic wave propagation in the atmosphere. In this paper, a short overview and current status of Acoustic travel-time Tomography of the atmosphere are presented. A brief description of a 3D array for Acoustic Tomography of the atmosphere which is being built at the Boulder Atmospheric Observatory is given. Furthermore, different inverse algorithms for reconstruction of temperature and velocity fields are discussed, including stochastic inversion and a recently developed time-dependent stochastic inversion. The latter inverse algorithm was used to reconstruct temperature and wind velocity fields in Acoustic Tomography experiments. Examples of the reconstructed fields are presented and discussed.

  • IGARSS - Array for Acoustic Tomography of the atmosphere
    IEEE International Geoscience and Remote Sensing Symposium, 2002
    Co-Authors: Vladimir E. Ostashev, Alfred J. Bedard, A. Voronovich
    Abstract:

    Tomography has been widely used in many fields of science, medicine and technology for remote sensing of different media. Acoustic Tomography of the atmosphere allows one to reconstruct the three-dimensional temperature and velocity fields and to monitor their evolution in time. It was first employed in the 1990s. In this paper, we overview arrays for Acoustic Tomography of the atmosphere which have been employed so far. Furthermore, we describe an Acoustic Tomography array which is proposed to be built at the NOAA Environmental Technology Laboratory. The array will allow us to remotely measure the temperature and velocity fields in a volume with the size of about 40 m/spl times/40 m/spl times/6 m, located at several meters above the ground. No currently existing meteorological instrumentation allows one to do such measurements. The temperature and velocity fields which will be reconstructed with the use of this array are important for many applications: boundary layer meteorology; propagation of Acoustic and electromagnetic waves in the atmosphere; experimental verification of large eddy simulation and direct numerical simulation; etc.

  • Array for Acoustic Tomography of the atmosphere
    IEEE International Geoscience and Remote Sensing Symposium, 2002
    Co-Authors: Vladimir E. Ostashev, Alfred J. Bedard, A. Voronovich
    Abstract:

    Tomography has been widely used in many fields of science, medicine and technology for remote sensing of different media. Acoustic Tomography of the atmosphere allows one to reconstruct the three-dimensional temperature and velocity fields and to monitor their evolution in time. It was first employed in the 1990s. In this paper, we overview arrays for Acoustic Tomography of the atmosphere which have been employed so far. Furthermore, we describe an Acoustic Tomography array which is proposed to be built at the NOAA Environmental Technology Laboratory. The array will allow us to remotely measure the temperature and velocity fields in a volume with the size of about 40 m/spl times/40 m/spl times/6 m, located at several meters above the ground. No currently existing meteorological instrumentation allows one to do such measurements. The temperature and velocity fields which will be reconstructed with the use of this array are important for many applications: boundary layer meteorology; propagation of Acoustic and electromagnetic waves in the atmosphere; experimental verification of large eddy simulation and direct numerical simulation; etc.