Providing roughness is an effective method to heat fluids to high temperature. Present paper make use of concave dimple roughness on one and three sides of roughened ducts aimed at determining rise in heat transfer and friction of three sides over one side roughened duct. Three sides roughened duct produces high heat transfer compared to one side roughened. Results are shown as a rise in Nusselt number and friction factor of three sides over one side roughened duct. Experimental investigation was conducted under actual outdoor condition at National Institute of Technology Jamshedpur, India to test various sets of roughened collectors. Roughness parameter varied as relative roughness pitch 8–15, relative roughness height 0.018–0.045, dimple depth to diameter ratio 1–2, Reynolds number 2500–13500 at fixed aspect ratio (width/hight) 8. Highest enhancement in Nusselt number for varying relative roughness pitch, height, and diameter ratio was respectively found as 2.6 to 3.55 times, 1.91 to 3.42 times and 3.09 to 3.94 times compared to one side dimple roughened duct. Highest rise in friction for three sides over one side roughened duct for these varying parameters was respectively found as 1.62 to 2.79 times, 1.52 to 2.34 times and 2.21 to 2.56 times. To visualize the effect of roughness parameter on heat transfer and friction factor, variation in Nusselt number and friction factor for varying roughness parameters with Reynolds number is shown.

The Gdansk chronicle by Bernt Stegmann was written in the East Central German language (Ostmitteldeutsch) in 1528 and is the oldest surviving historiographic artefact concerning Gdansk. The article sums up the author’s latest findings concerning the circumstances in which the chronicle was written and the probable addressee of the work. She also puts forward some hypotheses regarding the origin of the compiler, discusses the structure of the manuscript and the manner of its production.
The chronicle is a compilation of some older historiographic sources, which place the history of the Main City of Gdansk in world history: the Jerusalem rulers and the history of the Teutonic Order. It is a type of a universal town chronicle. The content is moralizing – the compilation is a collection of historical examples teaching how to rule the town properly. It was probably written for didactic purposes for young Hans Kremer, the future mayor of Gdansk.
Bernt Stegmann was a merchant trading in such places as Stockholm and Reval. The toponymic criterion indicates that his family could originate from the area of Brandenburg or Braniewo, while the dialect in which he wrote the chronicle as well as the numerous Silesian threads in the content also make it possible to be open to the hypothesis that Stegmann’s family could have come from Silesia. This question remains unresolved. The manuscript was written and made personally by Bernt Stegmann, as indicated by the atypical arrangement of its sections and non-professional binding.