An in-depth look at prior art in fast round-robin arbiter circuits

Arbiters are found where shared resources exist such as busses, switching fabrics, processing elements. Round-robin is a fair arbitration method, where requestors get near-equal shares of a common resource or service. Round-robin arbitration (RRA) finds use in network switches/routers and processor boards/systems as well as many other applications that have concurrency. Today's electronic systems require arbiters with hundreds of ports (e.g., switching fabrics with virtual I/O queues) and clock speeds near the limits of even the latest microelectronics fabrication processes/libraries. Achieving high clock speeds in the presence of large number of ports is only possible with highly parallel arbiter architectures. This paper presents an in-depth literature survey of previous work on this problem. It looks at RRA work in the literature in a bigger context, then defines the typical RRA problem (RRA_typical), and specifically investigates work on fast architectures that solve the RRA_typical problem. There are five such works that are really competitive. This report takes a very in-depth look at these works. It explains each architecture and how/why it works from a unique perspective that cannot be found in the original publication of that architecture. It also proposes improvements to these architectures. We wrote generators for the improved versions of these architectures. We will share a summary of synthesis results in this report – although a detailed account of how these results were obtained and their analysis is the subject of another (upcoming) publicatio

The free growth criterion for grain initiation in TiB

γ-titanium aluminide (γ-TiAl) based alloys enable for the design of light-weight and high-temperature resistant engine components. This work centers on a numerical study of the condition for grain initiation during solidification of TiB2 inoculated γ-TiAl based alloys. Grain initiation is treated according to the so-called free growth criterion. This means that the free growth barrier for grain initiation is determined by the maximum interfacial mean curvature between a nucleus and the melt. The strategy presented in this paper relies on iteratively increasing the volume of a nucleus, which partially wets a hexagonal TiB2 crystal, minimizing the interfacial energy and calculating the corresponding interfacial curvature. The hereby obtained maximum curvature yields a scaling relation between the size of TiB2 crystals and the free growth barrier. Comparison to a prototypical TiB2 crystal in an as cast γ-TiAl based alloy allowed then to predict the free growth barrier prevailing under experimental conditions. The validity of the free growth criterion is discussed by an interfacial energy criterion

Phase Transformations During Solidification of a Laser-Beam-Welded TiAl Alloy—An In Situ Synchrotron Study

An in situ highly time-resolved, high-energy X-ray diffraction investigation was carried out toobserve the phase transformations of a TiAl alloy during laser beam welding. The diffractionpatterns are recorded every 0.1 seconds by a fast area two-dimensional detector and plottedaccording to time, yielding the solidification pathway, the solid phase volume fraction, and thelattice parameter variation of different phases during the solidification and cooling process.Moreover, it is the first study that can demonstrate that the a phase without any Burgersorientation relationship, the so-called non-Burgers a, precipitates appear earlier than theBurgers a. The non-Burgers a grains are found to nucleate on the primary borides