Emissions from agricultural sources substantially contribute to global warming. The inverse dispersion method (IDM) has been successfully used for emission measurements from various agricultural ...sources. The IDM has also been validated in multiple studies with artificial gas releases mostly in open fields. Release experiments from buildings have rarely been conducted and were partly affected by additional nearby sources of the target gas. Specific release studies for naturally ventilated animal housings are lacking. In this study, a known and predefined amount of methane (CH4) was released from an artificial source inside a barn that mimicked a naturally ventilated dairy housing, and IDM recovery rates, using a backward Lagrangian stochastic (bLS) model, were determined. For concentration measurements, open-path devices (OPs) with a path length of 110 m were placed in a downwind direction of the barn at fetches of 2.0h, 5.3h, 8.6h, and 12h (h equals the height of the highest obstacle), and a 3D ultrasonic anemometer (UA) was placed in the middle of the first three OP paths. Upwind of the barn, an additional OP and a UA were installed. The median IDM recovery rates determined with the UA placed upwind of the barn and the downwind OP ranged between 0.55–0.75. It is concluded that, for the present study case, the effect of the building and a tree in the main wind axis led to a systematic underestimation of the IDM-derived emission rate probably due to deviations in the wind field and turbulent dispersion from the underlying assumptions of the used dispersion model.
Hat tricks Buhler, J. P.
The Mathematical intelligencer,
09/2002, Letnik:
24, Številka:
4
Journal Article
Recenzirano
Buhler discusses the infamous hats mathematical problem which has circulated widely in mathematics circles. In full generality it is a fiendishly difficult puzzle based on random possibilities and ...comes very close to the mathematics research frontier.
X-ray spectroscopy of kaonic atoms provides a versatile tool to study the strong interaction at low energies via a direct observation of its influence on the ground state of kaonic hydrogen atoms. ...The SIDDHARTA experiment provided precise results on the energy shift and width of the kaonic hydrogen 1s state induced by the strong interaction. To enable the extraction of the antikaon-nucleon scattering lengths a0 and a1, SIDDHARTA-2 aims to determine the energy shift and width in kaonic deuterium with precisions of 30 eV and 75 eV, respectively. This measurement is aggravated by the low kaonic deuterium X-ray yield and a high background environment and will only be possible by implementing a severe upgrade on the SIDDHARTA apparatus.
The pyrolysis products of polymethylsiloxanes (PMS) have been studied in order to characterize their phase composition from the viewpoint of equilibrium thermodynamics. Dilatometry measurements and ...redox analyses with PbO have been conducted and the results analysed and compared with respect to the second law of thermodynamics. In agreement with equilibrium thermodynamics, which shows that there is no ternary compound in the Si–O–C system, the experimental results imply that the pyrolysis residue is an amorphous or nanocrystalline composite consisting of a SiO2-phase matrix with embedded SiC and C particles. These findings seem to contradict the accepted scientific opinion of ternary silicon-oxycarbide phases.
The Angel of Jewish History casts a philosophical gaze upon the relationship between the traditional Jewish past and the present through the metaphysical worldviews of five formative Jewish studies ...scholars: Yosef Hayim Yerushalmi, Amos Funkenstein, Gershom Scholem, Baruch Kurzweil, and Nathan Rotenstreich. Their hermeneutic worldviews and writings deal with the nature and formation of modern Judaism, the Wissenschaft des Judentums, historicism, the image of the Jewish past and tradition, secularization, and God's status in present-day Jewish reality. In this volume, these issues are explored against the background of the tense discourse between the perception of modern Jewish reality as a break from the past and tradition and the argument for continuity despite the changes and developments of modernity.
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