Compute-and-forward is a framework for reliable physical layer network coding introduced by Nazer and Gastpar. Instead of decoding single messages, it decodes linear combinations of messages with the help of nested lattice codes. Nazer and Gastpar derived an achievable rate for each node depending on the channel coefficients and the desired equation coefficients. However, it is open how to choose the coefficient vector with the equation coefficients. We provide a branch-and-bound algorithm that calculates the coefficient vector, which results in the highest computation rate at a single node. We implemented the algorithm in Matlab and compared the number of iterations to the number of needed iterations if we use a complete search over all possible vectors.Index Terms-compute-and-forward, network coding, branch-and-bound algorithm
Electron zone-refined tungsten and molybdenum single crystals are deformed in tension a t room temperature. The slip systems on the cylinder-shaped tensile specimens are determined using the light as well as the electron microscope. The slip line pattern depends sensitively on the orientation of the stress axis. Single slip on the crystals investigated is not observed. The slip occurs preferentially on planes of type { 110}, but usually further slip planes of the <111> zone are also active. The slip band structure is discussed in terms of elementary slip processes.Elektronenzonengeschmolzene Wolfram-und Molybdln-Einkristalle wurden bei Raumtemperatur im Zugversuch verformt. Mittels licht-und elektronenmikroskopischer Methoden wurden die Gleitsysteme an den zylinderformigen Zugproben bestimmt. Das Gleitlinienbild war stark abhiingig von der Achsenorientierung. An den untersuchten Kristallen konnte keine Einfachgleitung beobachtet werden. Die Abgleitung erfolgte auf Ebenen vom Typ { 1103, aber meistens waren auch noch andere Gleitebenen der (111)-Zone wirksam. Die Gleitlinienstruktur wird in Verbindung mit elementaren Gleitprozessen diskutiert.
On four grades of medium carbon V‐bearing steels with additional Ti and Nb microalloying hot deformation tests were conducted as a simulation of hot forging. The aim of the study was to suggest general guidelines for the design of deformation patterns and cooling conditions of austenite. Both the resulting flow stresses and the strengthening/softening behaviour were taken into consideration. The maximum flow stresses appear to be insensitive both to the variation of microalloying and to the design of the deformation schedule over the range tested. Nevertheless, large differences can be achieved regarding austenite strengthening, especially its residual value at the begin of the γ‐α‐transformation which is decisive for the subsequent transformation process. A substantial effect of the final deformation temperature and the type of microalloying was ascertained.
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