With the increase of electronic device power density, thermal management and reliability are increasingly critical in the design of power electronic systems. First, increased density challenges the capability of conventional heat sinks to adequately dissipate heat. Secondly, higher frequency switching in high voltage, high current, wide bandgap power modules is creating intensified electromagnetic interference challenges, in which metallic heat removal systems will couple and create damaging current ringing. Furthermore, mobile power systems require lightweight heat removal methods that satisfy the heat loads dissipated during operation. In this effort we introduce an additive manufacturing pathway to produce custom heat removal systems using non-metallic materials, which take advantage of impinging fluid heat transfer to enable efficient thermal management. Herein, we leverage the precision of AM techniques in the development of 3D optimized flow channels for achieving enhanced effective convective heat transfer coefficients. The experimental performance of convective heat removal due to liquid impingement is compared with conventional heat sinks, with the requirement of simulating the heat transfer needed by a high voltage inverter. The implementation of non-metallic materials manufacturing is aimed to reduce electromagnetic interference in a low weight and reduced cost package, making it useful for mobile power electronics.

The spectral decomposition of graph adjacency matrices is an essential ingredient in the design of graph signal processing (GSP) techniques. When the adjacency matrix has multi-dimensional eigenspaces, it is desirable to base GSP constructions on a particular eigenbasis (the 'preferred basis'). In this paper, we provide an explicit and detailed representation-theoretic account for the spectral decomposition of the adjacency matrix of a Cayley graph, which results in a preferred basis. Our method applies to all (not necessarily quasi-Abelian) Cayley graphs, and provides descriptions of eigenvalues and eigenvectors based on the coefficient functions of the representations of the underlying group. Next, we use such bases to build frames that are suitable for developing signal processing on Cayley graphs. These are the Frobenius-Schur frames and Cayley frames, for which we provide a characterization and a practical recipe for their construction.

However, This has prevented the full utilization of the capability The resulting weld has a measured strength of between Single-point rock cutting Field tests of experimental bits are planned c

No abstract

With the increase of electronic device power density, thermal management and reliability are becoming increasingly important. First, increased density challenges the capability of conventional heat sinks to adequately dissipate heat. Secondly, higher frequency switching in wide bandgap power modules is introducing new issues in electromagnetic interference (EMI) in which metallic heat removal systems will couple and create damaging current ringing. Lastly, lightweight heat removal is required to meet the increasing needs of mobile power systems. In this effort we introduce an additive manufacturing pathway to produce custom-tailored heat removal systems using non-metallic materials, which take advantage of convective heat transfer to enable efficient thermal management. Herein, we leverage the precision of AM techniques in the development of 3D optimized flow channels for achieving enhanced effective convective heat transfer coefficients. The experimental performance of convective heat removal due to liquid impingement is compared with conventional heat sinks, with the requirement of simulating the heat transfer needed by a high voltage inverter. The implementation of non-metallic materials manufacturing is aimed to reduce EMI in a low weight and reduced cost package, making it useful for mobile power electronics.