The Effect of Tensioning and Wheel Tilting on the Torsional and Lateral Fundamental Frequencies of Bandsaw Blades

The effects of wheel tilting and saw tensioning on the natural fundamental frequencies of the lateral and torsional vibration of a stationary sawblade have been studied. Tensioning was found to increase the torsional fundamental frequency, but did not affect the lateral frequency. Wheel tilting, on the other hand, influenced both types of vibration by shifting the lateral fundamental frequency downward and the torsional frequency upward.In predicting the natural frequencies under operating conditions of a bandmill, only the effect of tensioning on torsional vibration has to be taken into account. The effect of wheel tilting was found to be essentially outside the range of tilting angles normally applied in practice

Untersuchungen zum mechanischen Verhalten von Aluminium/Magnesium-Werkstoffverbunden und deren Grenzschicht bei der weiteren Umformung

Die vorliegende Arbeit befasst sich mit dem Grenzschichtverhalten von Aluminium-Magnesium-Werkstoffverbunden während der Weiterverarbeitung durch Warmumformverfahren. Die Herstellung der Verbunde erfolgt mittels hydrostatischem Strangpressen, was zu einer stoffschlüssigen Verbindung in Form von intermetallischen Phasen führt.Während der weiteren Umformung zerbricht diese Grenzschicht in Fragmente ohne die stoffschlüssige Verbindung zu den Grundwerkstoffen aufzugeben. Die Auswirkungen dieser Fragmentierung auf die Grenzschichtfestigkeit wird mittels verschiedener Biegeversuche untersucht. Eine Eigenspannungsanalyse basierend auf dem Bohrlochverfahren und einer speziellen numerischenAuswertemethode ist ebenfalls Bestandteil dieser Arbeit. Es folgt die Aufstellung eines Fragmentierungskriteriums, das die kritische Streckung für das Einsetzen der Grenzschichtfragmentierung anzeigt. Grundlage bildet eine Vielzahl von Rinnenstauchversuchen mit einer neu entwickelten Probenform. Die nach der Fragmentierung zu beobachtende Grenzschichtkinematik wird mittels numerischer Simulation nachempfunden und so Beanspruchungszustände auf mikroskopischer Ebene zugänglich gemacht

Honeybees Learn Landscape Features during Exploratory Orientation Flights

Degen J, Kirbach A, Reiter L, et al. Honeybees Learn Landscape Features during Exploratory Orientation Flights. Current Biology. 2016;26(20):2800-2804

Predisposition to Cancer Caused by Genetic and Functional Defects of Mammalian Atad5

ATAD5, the human ortholog of yeast Elg1, plays a role in PCNA deubiquitination. Since PCNA modification is important to regulate DNA damage bypass, ATAD5 may be important for suppression of genomic instability in mammals in vivo. To test this hypothesis, we generated heterozygous (Atad5+/m) mice that were haploinsuffficient for Atad5. Atad5+/m mice displayed high levels of genomic instability in vivo, and Atad5+/m mouse embryonic fibroblasts (MEFs) exhibited molecular defects in PCNA deubiquitination in response to DNA damage, as well as DNA damage hypersensitivity and high levels of genomic instability, apoptosis, and aneuploidy. Importantly, 90% of haploinsufficient Atad5+/m mice developed tumors, including sarcomas, carcinomas, and adenocarcinomas, between 11 and 20 months of age. High levels of genomic alterations were evident in tumors that arose in the Atad5+/m mice. Consistent with a role for Atad5 in suppressing tumorigenesis, we also identified somatic mutations of ATAD5 in 4.6% of sporadic human endometrial tumors, including two nonsense mutations that resulted in loss of proper ATAD5 function. Taken together, our findings indicate that loss-of-function mutations in mammalian Atad5 are sufficient to cause genomic instability and tumorigenesis

An Experimental Study on The Lateral Natural Frequency of Bandsaw Blades

Two solutions for predicting the lateral natural frequency of bandsaw blades are experimentally verified for saw velocity, span length, and tension stress ("strain"). Both solutions are shown to be accurate provided that the effective span length of the guide system, which has been shown for pressure guides to exceed the distance between facing guide edges, is taken into account.It was found that wheel rotation can cause resonance vibration in the backside section of the sawblade, where the blade extending from wheel to wheel is unsupported. This resonance vibration, however, can be avoided by installing a guide midway between the wheels