Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: Infrared images of heat fields around a linear heater in tree trunks: what can be learned about sap flow measurement? | Ann. For. Sci. 63 2006 653-660 INRA EDP Sciences 2006 DOI forest 2006046 653 Original article Infrared images of heat fields around a linear heater in tree trunks what can be learned about sap flow measurement Helmut TRIBUTSCHa Nadezhda NADEZHDINAb Jan CERMAKb a Hahn-Meither Institute Dept. Solare Energetik 14109 Berlin Germany b Institute of Forest Ecology Mendel University of Agriculture and Forestry Zemedelska 3 Brno 61300 Czech Republic Received 23 September 2005 accepted 22 February 2006 Abstract - This contribution aims at improving the understanding of sap flow measurements in trees. Infrared heat field images taken around heating needles in sap transporting tree trunks are characterized by isotherms of elliptic shape with the heating needle in the lower focus. Increasing sap flow increases the eccentricity of the elliptic heat field. This dynamics of ellipses provides a simplified experimental-mathematical approach for the understanding and evaluation of the otherwise very complicated heat transfer- and distribution-problem involved. The results obtained are used to discuss criteria for possible improved positioning patterns for needle sensors aimed for sap flow calculation using the dynamics of ellipses. ellipse heat dissipation method heat field deformation method linear heater sensor geometry Résumé - Images infrarouges des champs de chaleur autour d un radiateur linéaire dans les troncs des arbres que peut-on apprendre au sujet de la mesure du flux de sève Cet article vise à améliorer la comprehension des mesures du flux de sève dans les arbres. Des images infrarouges prises autour des aiguilles de chauffage dans les troncs transportant la sève ont été caractérisées par des isothermes de forme elliptique avec l aiguille chauffante dans le foyer le plus bas. L accroissement du flux de sève accroĩt l excentricité du champ de chaleur elliptique. Ces dynamique des ellipses fournissent une approche expérimentale et mathématique simplifiée pour la .
