13 Articles found

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  • Comparing Optical Turbidity With LISST-ABS

    Comparing Optical Turbidity With LISST-ABS

    For measuring suspended sediments, the use of optical backscatter sensors or other turdibity sensors is widespread. At the same time, it is understood that these sensors respond to total particle area, not volume or mass. In other words, optical ...

  • How the LISST-ABS works

    How the LISST-ABS works

    INTRODUCTION: Sequoia’s Acoustic Backscatter Sensor, LISST-ABS is designed to measure suspended sediment concentration at a point. Unlike ADCP’s which may record similar backscatter strength at multiple points along the acoustic beams ...

  • Sensitivity of response of LISST-ABS and OBS to size distribution changes

    Sensitivity of response of LISST-ABS and OBS to size distribution changes

    This Note shows how the calibration of the LISST-ABS acoustic backscatter sensor and of optical backscatter sensor (OBS) changes when water contains a broad distribution of particle sizes, and why LISST-ABS is inherently superior. Particle size ...

  • Scintillation effect in LISST – The importance of temperature differences

    Scintillation effect in LISST – The importance of temperature differences

    Scintillation is what makes stars twinkle. It is what causes mirage in deserts or on hot surfaces. It is what causes shimmer underwater in the vicinity of hot vents in oceans. These effects result from temperature fluctuations in air or water. The ...

  • LISST-SL velocity thresholds

    LISST-SL velocity thresholds

    Is there a low velocity threshold for the LISST-SL? Does it need a minimum flow speed in order to sample? What is that? Absolutely! The internal pump in the SL will adjust the intake velocity to match the ambient flow speed in order to make the ...

  • What is the acceptance angle of the LISST instruments?

    What is the acceptance angle of the LISST instruments?

    The acceptance angle of the LISST-100X / LISST-STX transmission measurement differs between instruments: IN AIR, the LISST-100X type C has an acceptance angle of 0.0177 degrees while a type B has an acceptance angle of 0.0353 degrees. The ...

  • What type of batteries do the instruments use? How long do they last?

    What type of batteries do the instruments use? How long do they last?

    All instruments use custom made alkaline battery packs, except the LISST-Portable with touch panel display and the LISST-Portable|XR that uses rechargeable Lithium-Ion (Li-ion) batteries. Older versions of the LISST-Portable uses rechargeable Nickel ...

  • What is a shape model and which should I choose?

    What is a shape model and which should I choose?

    For the LISST-100X and LISST-Portable particle sizers, the user has an option to choose between two different shape models for inverting the scattering pattern into a size distribution. The two models are called Spherical and Randomly shaped ...

  • Grain size distribution and sediment flux structure in a river profile, measured with a LISST-SL instrument

    Grain size distribution and sediment flux structure in a river profile, measured with a LISST-SL instrument

    Abstract New data on sediment transport in a river are reported using a LISST-SL laser diffraction instrument that simultaneously measures velocity, optical transmission, depth, temperature, and sediment particle size distribution (PSD) ...

    Yogesh.C. Agrawal;Ole A. Mikkelsen;H. C. Pottsmith

  • Sauter mean diameter determination for the fine fraction of suspended sediments using a LISST-25X diffractometer

    Sauter mean diameter determination for the fine fraction of suspended sediments using a LISST-25X diffractometer

    ABSTRACT The L1SST-25X ability for measuring the Sauter mean diameter of the fine fraction of sediment samples, SMD/. is evaluated. A simple algorithm to determine the SMDf is proposed. The algorithm is based on the standard output variables from ...

    Leonardo Filippa;Alfredo Trento;Ana M. Alvarez

  • Using sediment particle size class analysis to better understand urban land-use effects

    Using sediment particle size class analysis to better understand urban land-use effects

    Abstract A nested-scale experimental watershed study design was used to demonstrate rainfall-runoff and sediment particle size class variability in a representative urbanizing watershed in central Missouri USA. On average, sediment particle size ...

    Jason A. Hubbart

  • Acceptance angle effects on the beam attenuation in the ocean

    Acceptance angle effects on the beam attenuation in the ocean

    Abstract The beam attenuation serves as a proxy for particulate matter and is a key parameter in visibility algorithms for the aquatic environment. It is well known, however, that the beam attenuation is a function of the acceptance angle of the ...

    Emmanuel Boss;Wayne H. Slade;M. Behrenfeld;G. Dall`Olmo

  • Light scattering by random shaped particles and consequences on measuring suspended sediments by laser diffraction

    Light scattering by random shaped particles and consequences on measuring suspended sediments by laser diffraction

    We present new observational data on small-angle light scattering properties of natural, random shaped particles, as contrasted with spherical particles. The interest in this "shape effect" on scattering arises from the need for a suitable kernel ...

    Yogesh.C. Agrawal;Amanda Whitmire;Ole A. Mikkelsen;H. C. Pottsmith