No abstract

A flashback phenomenon is reproduced by a direct numerical simulation (DNS) of a premixed hydrogen−air flame in a turbulent channel flow, and effects of the pressure oscillation, is caused by a virtual combustion instability on the flashback characteristics, are investigated. In addition, the interaction between the flashback flame structure and the turbulent flow structure is examined in detail. For the hydrogen−air reaction, a chemical reaction model, which considers 9 chemical species and 20 reactions, is employed. The results show that the pressure oscillation strongly affects the flashback characteristics, such as the flashback speed and heat flux on the wall, and is at risk for increasing the flashback speed, because the acceleration of the flashback speed by the pressure oscillation is greater than the deceleration of it. Independent of the pressure oscillation, the turbulent eddies passing through the flame tend to be suppressed and vanish by the acceleration of the streamwise flow caused by thermal expansion. However, other turbulent eddies are generated again in a form of longitudinal eddies behind the flame only at the cusps and center of the channel where the upper and lower flames meet, because of the strong fluid shear owing to the thermal expansion.

Abstract. Ozone is widely used for gas treatment, advanced oxidation processes, microorganisms inactivation, etc. In this research, we investigated the effect of nitrogen addition to ozone generation characteristics by atmospheric pressure Townsend discharge (APTD) type and filamentary dielectric barrier discharge (DBD) type ozone generators. The result showed that the ozone generated by the filamentary DBD increases rapidly with the increase of O 2 content, and is higher than that by the APTD. On the other hand, it is interesting that the ozone generated by the APTD gradually decreases with the increase of O2 content. In order to clarify why the characteristics of ozone generation by the two kinds of discharge modes showed different dependency to the N2 content, we analyzed the exhaust gas composition using FTIR spectroscopy and calculated the rate coefficients using BOLSIG+ code. As a result, we found that although O2 content decreased with increasing N2 content, additional O atoms produced by excited N2 molecules contribute to ozone generation in case of APTD.

Color images of single-photon emission computed tomography (SPECT) using technetium-99m(V) dimercaptosuccinic acid (99mTc(V)-DMS) were demonstrated in a patient with lung metastases from osteosarcoma. SPECT image using 99mTc(V)-DMS could be useful for the detection of lung metastasis from osteosarcoma.