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- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 6. |
- Li, X., et al.
(författare)
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Adaptive Resilient Secondary Control for Microgrids With Communication Faults
- 2021
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Ingår i: IEEE Transactions on Cybernetics. - : Institute of Electrical and Electronics Engineers (IEEE). - 2168-2267 .- 2168-2275. ; , s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- In this article, we consider the resilience problem in the presence of communication faults encountered in distributed secondary voltage and frequency control of an islanded alternating current microgrid. Such faults include the partial failure of communication links and some classes of data manipulation attacks. This practical and important yet challenging issue has been taken into limited consideration by existing approaches, which commonly assume that the measurement or communication between the distributed generations (DGs) is ideal or satisfies some restrictive assumptions. To achieve communication resilience, a novel adaptive observer is first proposed for each individual DG to estimate the desired reference voltage and frequency under unknown communication faults. Then, to guarantee the stability of the closed-loop system, voltage and frequency restoration, and accurate power sharing regardless of unknown communication faults, sufficient conditions are derived. Some simulation results are presented to verify the effectiveness of the proposed secondary control approach.
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| 7. |
- Li, Xiaolei, et al.
(författare)
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Resilience for Communication Faults in Reactive Power Sharing of Microgrids
- 2021
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Ingår i: IEEE Transactions on Smart Grid. - : Institute of Electrical and Electronics Engineers (IEEE). - 1949-3053 .- 1949-3061. ; 12:4, s. 2788-2799
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we consider the distributed reactive power sharing control problem for an autonomous inverter-based microgrid with resilience for communication faults, which may be caused by partial communication link failures or some channel manipulation attacks. Under the standard decoupling approximation for bus angle differences, the reactive power flow of each inverter can be controlled by manipulating the voltage amplitudes of itself and its neighbour inverters. By designing an adaptive resilient cooperative control scheme, accurate reactive power sharing can be guaranteed even in the presence of communication faults. Some simulation results are presented to verify the superiority of the proposed control approach compared with the existing methods.
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| 9. |
- Wang, Ci, et al.
(författare)
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Twinning pathways in Fe and Fe-Cr alloys from first-principles theory
- 2021
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Ingår i: Acta Materialia. - : Elsevier BV. - 1359-6454 .- 1873-2453. ; 215
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Tidskriftsartikel (refereegranskat)abstract
- Using density-functional theory, we determine the generalized stacking fault energy (GSFE) for the {1 (1) over bar 12} < 1 (1) over bar 11 > twinning system in ferromagnetic (FM) body-centered cubic Fe and Fe-Cr alloys with molar fraction of Cr <= 0.5. We adopt both reflection and isosceles twinning pathways and reveal the magnetic ordering effects on the GSFE by contrasting the FM results to those obtained for the magnetically disordered paramagnetic (PM) state. The results show that the isosceles twin boundary configuration is energetically preferred in this binary. The loss of long-range magnetic order lowers the GSFE amplitude but increases the twin boundary migration (TBM) energy regardless of the Cr content. The twin boundary formation (TBF) energy and the TBM energy show non-linear dependences on Cr content in the FM and PM states, and the effect of Cr on these properties critically depends on the magnetic state. We discuss our results in regard to the stable twin boundary structure and deformation twinning experimentally observed in homogeneous Fe-50 wt.% Cr alloy up to temperatures slightly above the magnetic ordering temperature.
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| 10. |
- Yang, Qiyu, et al.
(författare)
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Adaptive distributed synchronization of heterogeneous multi-Agent systems over directed graphs with time-Varying edge weights
- 2021
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Ingår i: Journal of the Franklin Institute. - : Elsevier BV. - 0016-0032. ; 358:4, s. 2434-2452
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Tidskriftsartikel (refereegranskat)abstract
- Time-varying edge weights represent dynamical interactions between any two nodes in multi-agent systems (MASs). In this paper, we consider a synchronization problem for heterogeneous MASs over directed graphs with time-varying edge weights from a control-theoretic perspective. We seek for an adaptive control protocol that drives the synchronization error in the presence of time-varying edge weights to converge in terms of asymptotic stability. We propose a class of observer networks for estimating leaders and output regulation equation solvers built on directed graphs with time-varying edge weights. Finally, we use a simulation study to verify the effectiveness of the proposed protocol.
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