84,500 research outputs found
A Convex Cycle-based Degradation Model for Battery Energy Storage Planning and Operation
A vital aspect in energy storage planning and operation is to accurately
model its operational cost, which mainly comes from the battery cell
degradation. Battery degradation can be viewed as a complex material fatigue
process that based on stress cycles. Rainflow algorithm is a popular way for
cycle identification in material fatigue process, and has been extensively used
in battery degradation assessment. However, the rainflow algorithm does not
have a closed form, which makes the major difficulty to include it in
optimization. In this paper, we prove the rainflow cycle-based cost is convex.
Convexity enables the proposed degradation model to be incorporated in
different battery optimization problems and guarantees the solution quality. We
provide a subgradient algorithm to solve the problem. A case study on PJM
regulation market demonstrates the effectiveness of the proposed degradation
model in maximizing the battery operating profits as well as extending its
lifetime
Thermal and Non-thermal radiation from pulsars: hints of physics
Thermal and non-thermal radiation from pulsars carries significant
information from surface and would have profound implications on the state of
dense matter in compact stars. For the non-thermal radio emission, subpulse
drifting phenomena suggest the existence of Ruderman-Sutherland-like
gap-sparking and strong binding of particles on pulsar polar caps. While
conventional neutron star models can hardly provide such a high binding energy,
the strong self-bound surface of quark-cluster stars can naturally solve this
problem. As for the thermal one, the featureless X-ray spectra of pulsars may
indicate a bare surface without atmosphere, and the ultrarelativistic fireball
of gamma-ray bursts and supernovae would also require strong self-bound
surfaces. Recent achievements in measuring pulsar mass and mass-radius relation
further indicate a stiff equation of state and a self-bound surface. Therefore,
we conjecture that matters inside pulsar-like compact stars could be in a
quark-cluster phase. The surface of quark-cluster stars is chromatically
confined and could initially be bare. Such a surface can not only explain above
features, but may also promote a successful core-collapse supernova, and the
hydro-cyclotron oscillation of the electron sea above the surface could be
responsible for those absorption features detected in the X-ray spectrum.Comment: 4 pages, contribution to the ERPM conferences, Zielona Gora, April
201
Environmentally Friendly Pervious Concrete for Treating Deicer-Laden Stormwater: Phase I
A graphene oxide-modified pervious concrete was developed by using low-reactivity, high-calcium fly ash as sole binder and chemical activators and other admixtures. The density, void ratio, mechanical strength, infiltration rate, Young’s modulus, freeze-deicer salt scaling, and degradation resistance of this pervious concrete were measured against three control groups. The test results indicate that graphene oxide modified fly ash pervious concrete is comparable to Portland cement pervious concrete. While the addition of 0.03% graphene oxide (by weight of fly ash) noticeably increased the compressive strength, split tensile strength, Young’s modulus, freeze-deicer salt scaling, and degradation resistance of fly ash pervious concrete, it reduced the void ratio and infiltration rate. The fly ash pervious concrete also showed unfavorable high initial loss during the freeze-deicer salt scaling test, which may be attributed to the low hydration degree of fly ash at early age. It is recommended that durability tests for fly ash concrete be performed at a later age
Environmentally Friendly Pervious Concrete for Treating Deicer-Laden Stormwater: Phase II
In Phase I of this project, graphene oxide (GO)-modified pervious concrete was developed using coal fly ash as the sole binder. The primary objectives of Phase II of this project were (1) to evaluate the stormwater infiltration capacity of GO-modified fly ash pervious concrete; (2) to evaluate the durability performance of GO-modified fly ash pervious concrete using freeze/thaw and salt resistance testing methods; and (3) to use advanced analytical tools to fully characterize the GO-modified fly ash binder. Test results indicate different degrees of reduction in concentrations of possible pollutants in stormwater—copper, zinc, sulphate, chloride, ammonia, nitrate, and total phosphate. The incorporation of GO significantly improved the resistance of pervious concrete to freeze/thaw cycles and ambient-temperature salt attack. The specimens were examined using X-ray diffraction, which revealed that the mineralogy and the chemical composition of fly ash pastes differ considerably from those of cement pastes. Nuclear magnetic resonance was used to study the chemical structure and ordering of different hydrates, and provided enhanced understanding of the freeze/thaw and salt scaling resistance of fly ash pervious concrete and the role of GO
Experimental study of quantum random number generator based on two independent lasers
Quantum random number generator (QRNG) can produce true randomness by
utilizing the inherent probabilistic nature of quantum mechanics. Recently, the
spontaneous-emission quantum phase noise of the laser has been widely deployed
for QRNG, due to its high rate, low cost and the feasibility of chip-scale
integration. Here, we perform a comprehensive experimental study of phase-noise
based QRNG with two independent lasers, each of which operates in either
continuous-wave (CW) or pulsed mode. We implement QRNGs by operating the two
lasers in three configurations, namely CW+CW, CW+pulsed and pulsed+pulsed, and
demonstrate their tradeoffs, strengths and weaknesses.Comment: 7pages,6figures.It has been accepted by PR
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