The star-switched MMC (SSMMC): a hybrid VSC for HVDC applications

This paper presents a new hybrid VSC topology (the Star-Switched MMC) – suitable for HVDC applications. The basic structure and operating principles of the topology are described. Control strategies that regulate the power exchanged between the VSC, the AC network and the DC network are presented. A modulation strategy ensuring appropriate switching of the individual chain-link sub-modules and a capacitor voltage balancing algorithm that ensures the capacitor voltages are maintained within the required tolerance are discussed. Results from a simulation model are presented to validate the expected performance of the converter and the proposed control schemes

Parallel Architectures for Planetary Exploration Requirements (PAPER)

The Parallel Architectures for Planetary Exploration Requirements (PAPER) project is essentially research oriented towards technology insertion issues for NASA's unmanned planetary probes. It was initiated to complement and augment the long-term efforts for space exploration with particular reference to NASA/LaRC's (NASA Langley Research Center) research needs for planetary exploration missions of the mid and late 1990s. The requirements for space missions as given in the somewhat dated Advanced Information Processing Systems (AIPS) requirements document are contrasted with the new requirements from JPL/Caltech involving sensor data capture and scene analysis. It is shown that more stringent requirements have arisen as a result of technological advancements. Two possible architectures, the AIPS Proof of Concept (POC) configuration and the MAX Fault-tolerant dataflow multiprocessor, were evaluated. The main observation was that the AIPS design is biased towards fault tolerance and may not be an ideal architecture for planetary and deep space probes due to high cost and complexity. The MAX concepts appears to be a promising candidate, except that more detailed information is required. The feasibility for adding neural computation capability to this architecture needs to be studied. Key impact issues for architectural design of computing systems meant for planetary missions were also identified

On the Energy Efficiency of MapReduce Shuffling Operations in Data Centers

This paper aims to quantitatively measure the impact of different data centers networking topologies on the performance and energy efficiency of shuffling operations in MapReduce. Mixed Integer Linear Programming (MILP) models are utilized to optimize the shuffling in several data center topologies with electronic, hybrid, and all-optical switching while maximizing the throughput and reducing the power consumption. The results indicate that the networking topology has a significant impact on the performance of MapReduce. They also indicate that with comparable performance, optical-based data centers can achieve an average of 54% reduction in the energy consumption when compared to electronic switching data centers