51,773 research outputs found
An Energy Efficient Knee Locking Mechanism for a Dynamically Walking Robot
In this work, we present the design and the implementation of an innovative knee locking mechanism for a dynamically walking robot. The mechanism consists of a four-bar linkage that realizes a mechanical singularity for locking the knee when the leg is in the extended position. Once extended, the knee remains locked without energy consumption, while unlocking it only costs a small amount of energy. Tests showed that the robot walks robustly and that the energy consumption of the new system is low
Unlocking Local Energy Markets
This is the final version. Freely available from University of Exeter Energy Policy Group via the link in this recordEuropean Regional Development FundCentric
Numerical simulation of the twist-grain-boundary phase of chiral liquid crystals
We study the core structure of the twist-grain-boundary (TGB) phase of chiral
liquid crystals by numerically minimizing the Landau-de Gennes free energy. We
analyze the morphology of layers at the grain boundary, to better understand
the mechanism of frustration between the smectic layer order and chirality. As
the chirality increases, the effective bending rigidity of layers is reduced
due to unlocking of the layer orientation and the director. This results in
large deviation of the layer morphology from that of Scherk's first minimal
surface and linear stack of screw dislocations (LSD).Comment: 4 pages and 6 figure
Role of Strange Quark Mass in Pairing Phenomena in QCD
We study the dynamical effect of strange quark mass as well as kinematical
one on the color-flavor unlocking transition using a NJL model. Paying a
special attention to the multiplicity of gap parameters, we derive an exact
formula of the effective potential for 5-gap parameters. Based on this, we
discuss that the unlocking transition might be of second order rather than of
first order as is predicted by a simple kinematical criterion for the
unlocking.Comment: 10 pages, talk at the KIAS-APCTP International Symposium on
Astro-Hadron Physics "Compact Stars: Quest for New States of Dense Matter
Unlocking Energy
Locks are a natural place for improving the energy efficiency of software systems. First, concurrent systems are mainstream and when their threads synchronize, they typically do it with locks. Second, locks are well-defined abstractions, hence changing the algorithm implementing them can be achieved without modifying the system. Third, some locking strategies consume more power than others, thus the strategy choice can have a real effect. Last but not least, as we show in this paper, improving the energy efficiency of locks goes hand in hand with improving their throughput. It is a win-win situation. We make our case for this throughput/energy-efficiency correlation through a series of observations obtained from an exhaustive analysis of the energy efficiency of locks on two modern processors and six software systems: Memcached, MySQL, SQLite, RocksDB, HamsterDB, and Kyoto Kabinet. We propose simple lock-based techniques for improving the energy efficiency of these systems by 33% on average, driven by higher throughput, and without modifying the systems
Gapless Color Superconductivity
We present the dispersion relations for quasiparticle excitations about the
color-flavor locked ground state of QCD at high baryon density. In the presence
of condensates which pair light and strange quarks there need not be an energy
gap in the quasiparticle spectrum. This raises the possibility of gapless color
superconductivity, with a Meissner effect but no minimum excitation energy.
Analysis within a toy model suggests that gapless color superconductivity may
occur only as a metastable phase.Comment: 4 pages, Revtex, eps figures include
Unlocking the Potential of Flexible Energy Resources to Help Balance the Power Grid
Flexible energy resources can help balance the power grid by providing
different types of ancillary services. However, the balancing potential of most
types of resources is restricted by physical constraints such as the size of
their energy buffer, limits on power-ramp rates, or control delays. Using the
example of Secondary Frequency Regulation, this paper shows how the flexibility
of various resources can be exploited more efficiently by considering multiple
resources with complementary physical properties and controlling them in a
coordinated way. To this end, optimal adjustable control policies are computed
based on robust optimization. Our problem formulation takes into account power
ramp-rate constraints explicitly, and accurately models the different
timescales and lead times of the energy and reserve markets. Simulations
demonstrate that aggregations of select resources can offer significantly more
regulation capacity than the resources could provide individually.Comment: arXiv admin note: text overlap with arXiv:1804.0389
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