Eddy Covariance flux errors due to random and systematic timing errors during data acquisition

Modern eddy covariance (EC) systems collect high-frequency data (10–20 Hz) via digital outputs of instru ments. This is an important evolution with respect to the tra ditional and widely used mixed analog/digital systems, as fully digital systems help overcome the traditional limita tions of transmission reliability, data quality, and complete ness of the datasets

Eddy covariance flux errors due to random and systematic timing errors during data acquisition

Modern eddy covariance (EC) systems collect high-frequency data (10–20&thinsp;Hz) via digital outputs of instruments. This is an important evolution with respect to the traditional and widely used mixed analog/digital systems, as fully digital systems help overcome the traditional limitations of transmission reliability, data quality, and completeness of the datasets.However, fully digital acquisition introduces a new problem for guaranteeing data synchronicity when the clocks of the involved devices themselves cannot be synchronized, which is often the case with instruments providing data via serial or Ethernet connectivity in a streaming mode. In this paper, we suggest that, when assembling EC systems in-house, aspects related to timing issues need to be carefully considered to avoid significant flux biases.By means of a simulation study, we found that, in most cases, random timing errors can safely be neglected, as they do not impact fluxes significantly. At the same time, systematic timing errors potentially arising in asynchronous systems can effectively act as filters leading to significant flux underestimations, as large as 10&thinsp;%, by means of attenuation of high-frequency flux contributions. We characterized the transfer function of such filters as a function of the error magnitude and found cutoff frequencies as low as 1&thinsp;Hz, implying that synchronization errors can dominate high-frequency attenuations in open- and enclosed-path EC systems. In most cases, such timing errors neither be detected nor characterized a posteriori. Therefore, it is important to test the ability of traditional and prospective EC data logging systems to assure the required synchronicity and propose a procedure to implement such a test relying on readily available equipment.</p

Finding New Genes for Non-Syndromic Hearing Loss through an In Silico Prioritization Study

At present, 51 genes are already known to be responsible for Non-Syndromic hereditary Hearing Loss (NSHL), but the knowledge of 121 NSHL-linked chromosomal regions brings to the hypothesis that a number of disease genes have still to be uncovered. To help scientists to find new NSHL genes, we built a gene-scoring system, integrating Gene Ontology, NCBI Gene and Map Viewer databases, which prioritizes the candidate genes according to their probability to cause NSHL. We defined a set of candidates and measured their functional similarity with respect to the disease gene set, computing a score () that relies on the assumption that functionally related genes might contribute to the same (disease) phenotype. A Kolmogorov-Smirnov test, comparing the pair-wise distribution on the disease gene set with the distribution on the remaining human genes, provided a statistical assessment of this assumption. We found at a p-value that the former pair-wise is greater than the latter, justifying a prioritization strategy based on the functional similarity of candidate genes respect to the disease gene set. A cross-validation test measured to what extent the ranking for NSHL is different from a random ordering: adding 15% of the disease genes to the candidate gene set, the ranking of the disease genes in the first eight positions resulted statistically different from a hypergeometric distribution with a p-value and a power. The twenty top-scored genes were finally examined to evaluate their possible involvement in NSHL. We found that half of them are known to be expressed in human inner ear or cochlea and are mainly involved in remodeling and organization of actin formation and maintenance of the cilia and the endocochlear potential. These findings strongly indicate that our metric was able to suggest excellent NSHL candidates to be screened in patients and controls for causative mutations

Dokumentation der Energie und Massenstrombilanzierung für ADAM I im Online-Betrieb

The methanation process is of considerable importance to both the production of "Substitute Natural Gas" on the basis of coal gasification and the "Nuclear Long - Distance Energy System". The report describes how the data resulting from experiments with pilot plant ADAM I were recorded and integrated into a computer program. The experimental results are of use to the optimization of the methanation process within the "Nuclear Long-Distance Energy System.

Methanolsynthese mit CO2_{2}-reichem Synthesegas aus der Erdgas-Reformierung mit H2_{2}O und CO2_{2}

In diesem Bericht werden Versuchsergebnisse aus Experimenten mit den Pilotanlagen zur Umwandlung von Erdgas in Methanol diskutiert. Durch Variation der Betriebsparameter bei der Reformierung von Erdgas mit H$_{2}$O und CO$_{2}$ wurden Synthesegase unterschiedlichen CO$_{2}$-Gehaltes erzeugt und der Einfluß auf die Methanolsynthese studiert. Mit steigendem CO$_{2}$-Gehalt sinkt die Methanolausbeute. Ursache hierfür ist sowohl eine Verschiebung des thermodynamischen Gleichgewichtes als auch eine Verlangsamung der Reaktionskinetik. Dieses Verhalten kann mit einem kinetischen Rechenmodell simuliert werden

Methanolsynthese mit CO_2-reichem Synthesegas aus der Erdgas-Reformierung mit H_2O und CO_2

SIGLETIB: RN 5906(580) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman