Archive for October, 2012

Sap Flow Tool 1.3 Released

Tuesday, October 16th, 2012

Sap Flow Tool 1.3 has been released. It is a major release which includes some of the most requested features to date: importing and visualising non-sap flow data (even non-ICT International data) and custom graphs for combining data from multiple sensors and/or files.

The new version can be downloaded here (including a demo version).

New features:

General

  • NEW “visualise module”: custom graphs, display data from multiple sensors and files (even non-ICT International data).
  • Value inspector slider on all graphs: shows numerical value of all curves at the slider position.
  • Option to show DOY on graph x-axis.
  • Ability to search in the user manual.

Files window

  • Import any data file (sap flow calculations still limited to ICT International .csv and .bin files).
  • Quick view graph: plot the currently selected item in the Files window.
  • Batch import of multiple data files + drag & drop in the Files window.
  • Batch export of multiple sensors.
  • Auto-reimport exported data.
  • Merge data from the same sensor in different files.
  • Files window filter: show only items that match certain criteria.
  • Move files up and down in the Files window.

Visualise module

  • Custom graphs, display data from multiple sensors and files.
  • Apply data filters to any curve on the graph.
  • Export all data from the custom graphs.
  • New example: sample 6, shows the use of custom graphs and non-sap flow data.

Overview video:

http://www.youtube.com/watch?v=Rvw2Bc5uMkc

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PhytoSim used in sap flow research

Tuesday, October 2nd, 2012

In a recently published paper about a new sap flow measurement technique (Sapflow+) PhytoSim was used to develop, simulate and calibrate the Sapflow+ model. Besides that, the PhytoSim sensitivity and identifiability analysis was also used to determine if the heat velocity, volumetric heat capacity and thermal conductivities could be estimated from the measured data.

Reference:

Vandegehuchte M.W. and Steppe K. (2012). Sapflow+: a four-needle heat-pulse sap flow sensor enabling nonempirical sap flux density and water content measurements. New Phytologist, 196(1), 306-317. http://onlinelibrary.wiley.com/doi/10.1111/j.1469-8137.2012.04237.x/abstract

Abstract:

  • To our knowledge, to date, no nonempirical method exists to measure reverse, low or high sap flux density. Moreover, existing sap flow methods require destructive wood core measurements to determine sapwood water content, necessary to convert heat velocity to sap flux density, not only damaging the tree, but also neglecting seasonal variability in sapwood water content.
  • Here, we present a nonempirical heat-pulse-based method and coupled sensor which measure temperature changes around a linear heater in both axial and tangential directions after application of a heat pulse. By fitting the correct heat conduction–convection equation to the measured temperature profiles, the heat velocity and water content of the sapwood can be determined.
  • An identifiability analysis and validation tests on artificial and real stem segments of European beech (Fagus sylvatica L.) confirm the applicability of the method, leading to accurate determinations of heat velocity, water content and hence sap flux density.
  • The proposed method enables sap flux density measurements to be made across the entire natural occurring sap flux density range of woody plants. Moreover, the water content during low flows can be determined accurately, enabling a correct conversion from heat velocity to sap flux density without destructive core measurements.
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