Hendrik F. Hamann

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Power-related issues have become important considerations in current generation microprocessor design. One of these issues is that of elevated on-chip temperatures. This has an adverse effect on cooling cost and, if not addressed suitably, on chip reliability. In this paper we investigate the general trade-offs between temporal and spatial hot spot(More)
It is known that light can be slowed down in dispersive materials near resonances. Dramatic reduction of the light group velocity-and even bringing light pulses to a complete halt-has been demonstrated recently in various atomic and solid state systems, where the material absorption is cancelled via quantum optical coherent effects. Exploitation of slow(More)
A large portion of the power consumption of data centers can be attributed to cooling. In dynamic thermal management mechanisms for data centers and servers, thermal setpoints are typically chosen statically and conservatively, which leaves significant room for improvement in the form of improved energy efficiency. In this paper, we propose two hierarchical(More)
In this paper we discuss a novel sensing and measurement technology which allows visualizing the 3D temperature and heat distributions in a data center or other complex thermal system. Specifically, we leverage the high spatial resolution of IBM's mobile measurement technology (MMT). We show that substantially improvements in energy efficiency can be(More)
We present characterization results of microscopic platinum wires as bolometers. The wire lengths range from 16 μm down to 300 nm. Thus they are in many cases significantly smaller in size than the wavelength of the radiation from the 1200 K blackbody source they were exposed to. We observe a steep rise in both responsivity ℜ and detectivity D* with(More)
Hotspots in data center have been attributed to an increase in equipment failures, which causes system down time and business loss. In maintenance of IT equipment, removing hotspot with minimal cooling power cost is both ecological and financial benefits. Thus, identifying root cause of hotspots in data center is essential. A variety of factors can cause(More)
Phase-change storage is widely used in optical information technologies (DVD, CD-ROM and so on), and recently it has also been considered for non-volatile memory applications. This work reports advances in thermal data recording of phase-change materials. Specifically, we show erasable thermal phase-change recording at a storage density of 3.3 Tb inch(-2),(More)
The sharp rise in energy usage in data centers, fueled by increased IT workload and high server density, and coupled with a concomitant increase in the cost and volatility of the energy supply, have triggered urgent calls to improve data center energy efficiency. In response, researchers have developed energy-aware IT systems that slow or shut down servers(More)
efficiency opportunities in data centers H. F. Hamann T. G. van Kessel M. Iyengar J.-Y. Chung W. Hirt M. A. Schappert A. Claassen J. M. Cook W. Min Y. Amemiya V. López J. A. Lacey M. O’Boyle The combination of rapidly increasing energy use of data centers (DCs), which is triggered by dramatic increases in IT (information technology) demands, and increases(More)
Geospatial data volume exceeds hundreds of Petabytes and is increasing exponentially mainly driven by images/videos/data generated by mobile devices and high resolution imaging systems. Fast data discovery on historical archives and/or real time datasets is currently limited by various data formats that have different projections and spatial resolution,(More)