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Proponents of AC-powered data centers have implicitly assumed that the electrical load presented to all three phases of an AC data center are balanced. To assure this, servers are connected to the AC power phases to present identical loads, assuming an uniform expected utilization level for each server. We present an experimental study that demonstrates that with the inevitable temporal changes in server workloads or with dynamic sever capacity management based on known daily load patterns, balanced electrical loading across all power phases cannot be maintained. Such imbalances introduce a reactive power component that represents an effective power loss and brings down the overall energy efficiency of the data center, thereby resulting in a handicap against DC-powered data centers where such a loss is absent.
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Novel modulated equivalent model of point-to-point LCC-based high voltage AC/DC/AC system for geomagnetic storm-induced unbalanced harmonic studies
- Award ID(s):
- 1650544
- PAR ID:
- 10215626
- Date Published:
- Journal Name:
- International Journal of Electrical Power & Energy Systems
- Volume:
- 122
- Issue:
- C
- ISSN:
- 0142-0615
- Page Range / eLocation ID:
- 106173
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Proponents of AC-powered data centers have implicitly assumed that the electrical load presented to all three phases of an AC data center are balanced. To assure this, servers are connected to the AC power phases to present identical loads, assuming an uniform expected utilization level for each server. We present an experimental study that demonstrates that with the inevitable temporal changes in server workloads or with dynamic sever capacity management based on known daily load patterns, balanced electrical loading across all power phases cannot be maintained. Such imbalances introduce a reactive power component that represents an effective power loss and brings down the overall energy efficiency of the data center, thereby resulting in a handicap against DC-powered data centers where such a loss is absent.more » « less
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Abstract Electrospinning is increasingly used as a staple technology for the fabrication of nano‐ and micro‐fibers of different materials. Most processes utilize direct current (DC) electrospinning, and a multitude of DC‐electrospinning tools ranging from research to commercial production systems is currently available. Yet, there are numerous studies performed on electrospinning techniques utilizing non‐DC, periodic electric fields, or alternating current (AC) electrospinning. Those studies demonstrate the strong potential of AC‐electrospinning for the sustainable production of various nanofibrous materials and structures. Although tremendous progress is achieved in the development of AC‐electrospinning over the last 10 years, this technique remains uncommon. This paper reviews the AC‐electrospinning concepts, instrumentation, and technology. The main focus of this review is the most studied, “electric wind” driven AC‐electrospinning technique tentatively named alternating field electrospinning (AFES). The latter term emphasizes the role of the AC electric field's confinement to the fiber‐generating electrode and the absence of a counter electrode in such an electrospinning system. The synopses of AFES process parameters, fiber‐generating spinneret designs, benefits and obstacles, advancements in AC electrospun nano/micro‐fibrous materials/structures and their applications are given, and future directions are discussed.more » « less
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1016/j.ijepes.2020.106173
