Search

Thermographic examination of 157 German Holstein heifer calves was performed to investigate the feasibility of this technique for on-farm recording of surface temperature of the head and to examine potential factors that affect the recordings. Baseline values were obtained from six defined locations on the head including both eyes, both horn buds, the muzzle and the mucous membrane of the muzzle using a high-end thermographic camera (ThermoPro TP8, Firma DIAS Infrared GmbH). Evaluation of the influence of various factors on thermographic measurements showed that ambient temperature had the largest effect on surface temperature of the head (regression coefficient, 0.10 to 0.32, p ≤ 0.01) whereas humidity had no effect (in t-test p ≥ 0.33 over all locations). There was a no correlation between rectal temperature and surface temperature (rp ≤ 0.05). The surface temperature decreased with increasing age of the calves (regression coefficient, - 0.42 to - 0.14, p ≤ 0.01). The agreement between double readings made shortly after one another was excellent at all locations (r ≥ 0.95). The emission of infrared energy varied among different locations; the most infrared energy was emitted by the eyes and the least by the muzzle. Paired locations (eyes and horn buds) had symmetric emission patterns of infrared energy. Measuring the surface temperature of the head of calves in their normal barn environment using a standardised protocol was feasible and thus could potentially be used for monitoring calves under field conditions.Mittels Infrarot-Thermographie wurden 157 gesunde, weibliche Deutsch-Holstein Kälber thermographisch untersucht. Es war das Ziel der Studie, Oberflächentemperaturen an definierten Lokalisationen im Kopfbereich von Deutsch-Holstein Kälbern unter Stallbedingungen standardisiert zu erfassen und die Einflussfaktoren auf die Ergebnisse zu charakterisieren. Im Rahmen der Studie wurden mittels einer High-End Wärmebildkamera (ThermoPro TP8, Firma DIAS Infrared GmbH) Ruhewerte von sechs Lokalisationen im Kopfbereich (linkes Auge (liAu), rechtes Auge (reAu), linke Hornanlage (liHa), rechte Horn­anlage (reHa), Flotzmaul (FM), Schleimhaut des Flotzmauls (SHFM)) erfasst. Die Umgebungstemperatur hatte einen Einfluss auf die Oberflächentemperaturen (r = 0,10 bis 0,32; p ≤ 0,01). Die Luftfeuchtigkeit wirkte sich nicht auf die Messergebnisse aus (im t-Test p ≥ 0,33 über alle Lokalisationen) . Es war kein Zusammenhang zwischen der rektal erfassten Körperinnentemperatur und den thermographisch ermittelten Oberflächentemperaturen feststellbar (rp ≤ 0,05). Mit zunehmendem Alter der Tiere konnte ein Abfall der Oberflächentemperaturen beobachtet werden (r = – 0,42 bis – 0,14; p ≤ 0,01). Die Wiederholbarkeit der thermographischen Doppelmessungen war sehr gut (r ≥ 0,95). An den verschiedenen Lokalisationen wurde Wärme in unterschiedlichem Maße emittiert, wobei die Augen die höchsten und das Flotzmaul die niedrigsten Oberflächentemperaturen aufwiesen. Die paarigen Lokalisationen (liAu:reAu, liHA:reHa) wiesen ein symmetrisches Wärmestrahlungsmuster auf. Die Thermographie kann im Kopfbereich von weiblichen Deutsch-Holstein Kälbern im Milchviehbetrieb zur Erfassung von unterschiedlichen Oberflächentemperaturen eingesetzt werden.Un total de 157 veaux femelles provenant d’un troupeau de 1 500 vaches holstein ont été examinées au moyen d’une caméra thermographique haut de gamme (Ther-moPro TP8, Firma DIAS Infrared GmbH). Le but de la présente étude était d’étudier la faisabilité de cette technique pour l’enregistrement à la ferme de la température de surface de la tête de veaux laitiers et d’examiner les facteurs potentiels qui affectent les enregistrements. Tous les veaux ont été doucement tenus par une personne formée afin de normaliser la procédure. Les valeurs de base ont été obtenues à partir de six endroits définis sur la tête, y compris les deux yeux, les deux boutons de corne, le mufle et la muqueuse du museau. L’évaluation de l’influence de divers facteurs sur les mesures thermographiques a montré que la température ambiante avait le plus grand effet sur la température de surface de la tête (coefficient de régression, 0,10 à 0,32, p ≤ 0,01) alors que l’humidité n’avait aucun effet (dans le test t, p ≥ 0,33 sur tous les lieux). Il n’y avait pas de corrélation entre la température rectale et la température de surface (rp ≤ 0,05). La température de surface diminuait avec l’âge des veaux (coefficient de régression, -0,42 à -0,14, p ≤ 0,01). La concordance entre les lectures doubles faites peu de temps après les autres était excellente dans tous les sites (r ≥ 0,95) L’émission d’énergie infrarouge variait selon les endroits. L’énergie infrarouge la plus importante a été émise par les yeux et la plus faible par le mufle. Les sites appariés (yeux et cornes) présentaient des profils d’émission symétriques d’énergie infrarouge. La thermographie peut être utilisée chez veaux Holstein pour la détection de différentes température de surface de la tête.La termografia a infrarossi è un metodo di imaging non invasivo, rapido e senza contatto, per la misurazione delle temperature superficiali utilizzata per diverse indicazioni mediche in medicina veterinaria. L’obiettivo del presente studio era quello di studiare la fattibilità di questa tecnica per la registrazione in stalla della temperatura superficiale della testa dei vitelli Holstein tedeschi e di esaminare i potenziali fattori che influenzano i risultati. A tale scopo, 157 giovenche sane di razza tedesca Holstein di un’azienda da latte con 1500 vacche sono state esaminate termograficamente con una telecamera termografica di fascia alta (ThermoPro TP8, DIAS Infrared GmbH). Tutti i vitelli sono stati trattenuti delicatamente da una persona addestrata per standardizzare la procedura. Nell’ambito dello studio si sono registrati i valori di riferimento ottenuti da sei posizioni localizzate sulla testa, (occhio sinistro (liAu), occhio destro (reAu), corno sinistro (liHa), corno destro (reHa), muso (FM), mucosa dello specchio nasolabiale (SHFM)). È stato esaminato in che modo determinati fattori hanno influenzato le misurazioni termografiche. La temperatura ambientale ha avuto la maggiore ­influenza sulle temperature superficiali (coefficienti di regressione da 0,10 a 0,32; p ≤ 0,01). L’umidità non ha influenzato i risultati della misurazione (nel test t p ≥ 0,33 su tutte le posizioni). Non vi è stata nessuna relazione tra la temperatura rettale registrata e la temperatura superficiale rilevabile termograficamente (rp ≤ 0,05), D’altra parte, con l’aumentare dell’età degli animali si può osservare una diminuzione delle temperature superficiali (coefficienti di regressione da - 0,42 a - 0,14; p ≤ 0,01). La ripetibilità delle doppie misurazioni termografiche consecutive per ogni localizzazione è stata molto buona (r ≥ 0,95). Il calore veniva emesso a vari livelli nelle varie posizioni, dove gli occhi avevano le temperature superficiali più alte e lo specchio nasolabiale le temperature superficiali più basse. Le posizioni accoppiate (liAu:reAu, liHA:reHa) presentavano modelli di radiazione simmetrica del calore. Pertanto, nelle aziende, un uso della termografia per il rilevamento delle temperature superficiali nell’area della testa delle giovenche di razza tedesca Holstein è possibile. Queste misurazioni forniscono la base per un potenziale uso della termografia per monitorare la salute dei vitelli.

The convective heat losses of cavity receivers for solar thermal power towers are of great importance for the overall efficiency of the whole system. However, the influence of wind on these losses has not been studied sufficiently for large scale cavity receivers with different inclination angles. In this present study the impact of head-on and side-on wind on large cavity receivers with inclination angles in the range of 0° (horizontal cavity) to 90° (vertical cavity) is analyzed numerically. The simulation results are compared to data published in literature. When no wind is present the losses decrease considerably with increasing inclination angle of the receiver. In case of a horizontal receiver wind does not have a huge impact on the losses: they remain constant on a high level. In case of an inclined cavity wind increases the heat losses significantly in most of the cases, although the highest absolute value of the losses occurs for the horizontal receiver exposed to head on wind. In some cases, when wind is flowing parallel to the aperture plane, a reduction of the heat losses is observed. The temperature distribution in the cavity is analyzed in order to explain the impact of wind on the heat losses. Wind in general causes a shrinking of the zone with uniform high temperature in the upper region of the cavity, whereas wind flowing parallel to the aperture plane additionally inhibits hot air from leaving the cavity and therefore leads to an increased temperature in the lower zone.