The sunspot groups have been observed since 1610 and their numbers have been used for evaluating the amplitude of solar activity. Daniel Mögling recorded his sunspot observations for more than 100 days in 1626-1629 and formed a significant dataset of sunspot records before the Maunder Minimum. Here, we have analysed his original manuscripts in the Universitäts-und Landesbibliothek Darmstadt (ULBD) to review Mögling's personal profile and observational instruments and derive number and positions of the sunspot groups. In his manuscript, we have identified 134 days with an exact sunspot group number and 3 days of additional descriptions. Our analyses have completely revised their observational dates and group number, added 19 days of hitherto overlooked observations, and removed 8 days of misinterpreted observations. We have also revisited sunspot observations of Schickard and Hortensius and revised their data. These results have been compared with the contemporary observations. Moreover, we have derived the sunspot positions from his sunspot drawings and located them at 2°-23° in the heliographic latitude in both solar hemispheres. Contextualised with contemporary observations, these results indicate their temporal migration to lower heliographic latitudes and emphasise its location in the declining phase

The aerodynamic characteristics of turbine cascades are thought to be relatively satisfactory due to the favorable pressure gradient of the accelerating flow. But within the low Reynolds number region of approximately 6×104 where the 300kW ceramic gas turbines which are being developed under the New Sunshine Project of Japan operate, the characteristics such as boundary layer separation, reattachment and secondary flow which lead to prominent power losses can not be easily predicted. In this research, experiments have been conducted to evaluate the performance of an annular turbine stator cascade. Wakes of the cascade were measured using a single hot wire and five hole pressure tube, for a range of blade chord Reynolds numbers based on the inlet condition from 2×104 to 12×104. Flow visualizations on the suction surface of the blade were carried out using oil film method. At low Reynolds numbers, the flow structure in the annular cascade was quite complex and three-dimensional. The separation line on the suction surface moved upstream due to the decrease of Reynolds number. In addition, the growth of secondary flows, i.e., passage vortices and leakage vortex, was extremely under the influence of Reynolds number.

Eirene Laskarina, Empress of John III Batatzes of the exiled Byzantine Empire of Nicaea (1204–1261 CE), was an important Eastern Mediterranean figure in the first half of the thirteenth century. We reassess the death day of Eirene, which has been variously dated during the years between the end of 1239 and 1241, with the understanding that narrowing the range in which this event occurred contributes much to understanding the political situation in the area around 1240. George Akropolites, a famous official of the Empire, gives an account that connects Eirene's death to a comet that appeared “six months earlier,” thus pointing to two comet candidates that were visible from the Eastern Mediterranean during the years 1239 and 1241, one recorded on “1239 June 3” and the other on “1240 January 31.” Recent historians prefer the former, based on historical circumstances and without a critical assessment of the comet records. We revisit the historical records and reveal that the “1239 June 3” candidate was not a comet. On the other hand, the other candidate was a comet, as supported by multiple historical records in multiple regions, and is also a good fit with Akropolites’ narrative. Therefore, we conclude that Eirene died six months after the comet that was seen on 1240 January 31, which places her death in the summer of 1240. Given that her death day is crucial for determining some other contemporary events across the Eastern Mediterranean, our results offer a solid basis for further research on the thirteenth-century Eastern Mediterranean.