Performance comparison of parallel optical interconnects for enterprise servers
There is an emerging need in the computing industry for higher bandwidth, longer distance, and increased density interconnections within clusters of high performance enterprise-class computer systems. Many of these servers share a common set of high level requirements which lend themselves to the use of parallel optical interconnects to either supplement or replace existing copper data buses. In this paper, we describe the results of application testing performed on 12-fiber parallel optical cables and connectors, including a relative comparison between three different multimode cable assembly sources. Assembly loss and effects of both axial and off-axis pull forces are measured for cable samples mated to a laser transmitter array. Significant variations exist in the performance of the same type of cable assembly from different manufacturing sources, particularly concerning their susceptibility to pull forces; we also investigate the effects of fiber strain relief to improve performance of these links. While currently available 12-fiber array connectors are not equivalent in performance to standard duplex connectors, this work suggests areas for future improvement and data communication application requirements which should be considered when using parallel fiber optic arrays.
Metropolitan area wavelength-division multiplexing testbeds for enterprise computing and disaster recovery
Fiber optic data communication networks face unique requirements for applications such as disaster recovery of multiterabyte and petabyte databases. We present experimental results from several enterprise computing testbeds that evaluate dense wavelength-division multiplexing (DWDM) performance in metropolitan area datacom networks. Many networking issues can be addressed through the components used within the DWDM platform; we discuss how current and emerging requirements can be addressed by new packages for 10-Gbit/s links, clock recovery circuits, and wavelength lockers. A comparison of three DWDM platforms evaluated in these testbeds is given, including features such as network bandwidth, scalability, performance over distance, and ease of management. We also report performance of datacom protocols such as enterprise system connection (ESCON), fiber connection (FICON), and FICON Bridge, when extended beyond industry standard distances using DWDM.
Laminar heat or mass transfer in rectangular channels and in cylindrical tubes for fully developed flow: comparison of solutions obtained for various boundary conditions
Abstract A comparison is made of results obtained with various boundary conditions at the wall of the channels. By comparing blood Sherwood numbers for finite wall resistance with those for constant concentration boundary condition only a small variation is found for various points along the blood channel.