This paper proposes an optimal bidding strategy in the day-ahead market of a microgrid consisting of intermittent distributed generation (DG), storage, dispatchable DG, and price responsive loads. ...The microgrid coordinates the energy consumption or production of its components, and trades electricity in both day-ahead and real-time markets to minimize its operating cost as a single entity. The bidding problem is challenging due to a variety of uncertainties, including power output of intermittent DG, load variation, and day-ahead and real-time market prices. A hybrid stochastic/robust optimization model is proposed to minimize the expected net cost, i.e., expected total cost of operation minus total benefit of demand. This formulation can be solved by mixed-integer linear programming. The uncertain output of intermittent DG and day-ahead market price are modeled via scenarios based on forecast results, while a robust optimization is proposed to limit the unbalanced power in real-time market taking account of the uncertainty of real-time market price. Numerical simulations on a microgrid consisting of a wind turbine, a photovoltaic panel, a fuel cell, a micro-turbine, a diesel generator, a battery, and a responsive load show the advantage of stochastic optimization, as well as robust optimization.
The traditional unit commitment and economic dispatch approaches with deterministic spinning reserve requirements are inadequate given the intermittency and unpredictability of wind power generation. ...Alternative power system scheduling methods capable of aggregating the uncertainty of wind power, while maintaining reliable and economic performance, need to be investigated. In this paper, a probabilistic model of security-constrained unit commitment is proposed to minimize the cost of energy, spinning reserve and possible loss of load. A new formulation of expected energy not served considering the probability distribution of forecast errors of wind and load, as well as outage replacement rates of various generators is presented. The proposed method is solved by mixed integer linear programming. Numerical simulations on the IEEE Reliability Test System show the effectiveness of the method. The relationships of uncertainties and required spinning reserves are verified.
Abstract
The Kagome superconductors AV
3
Sb
5
(A = K, Rb, Cs) have received enormous attention due to their nontrivial topological electronic structure, anomalous physical properties and ...superconductivity. Unconventional charge density wave (CDW) has been detected in AV
3
Sb
5
. High-precision electronic structure determination is essential to understand its origin. Here we unveil electronic nature of the CDW phase in our high-resolution angle-resolved photoemission measurements on KV
3
Sb
5
. We have observed CDW-induced Fermi surface reconstruction and the associated band folding. The CDW-induced band splitting and the associated gap opening have been revealed at the boundary of the pristine and reconstructed Brillouin zones. The Fermi surface- and momentum-dependent CDW gap is measured and the strongly anisotropic CDW gap is observed for all the V-derived Fermi surface. In particular, we have observed signatures of the electron-phonon coupling in KV
3
Sb
5
. These results provide key insights in understanding the nature of the CDW state and its interplay with superconductivity in AV
3
Sb
5
superconductors.
•Hydrodynamics and reactive characteristic of CLC in the DCFB is investigated.•The reactive multiphase model with considerations of cluster effects is applied.•Simulations are in agreement with ...experiments.•The effect of temperature and air/fuel ratio on gas compositions is predicted.
Chemical looping combustion (CLC) processes in a dual circulating fluidized bed (DCFB) reactor are investigated by means of computational fluid dynamic (CFD) method. A two-fluid model with consideration of heterogeneous chemical reactions is adopted. The kinetic theory of granular flow is employed for closure. A cluster structure-dependent (CSD) drag coefficient model is applied to account for the effect of meso-scale heterogeneous structure involving clusters or strands. The simulations are performed to predict gas–solid flow behaviors and reactive characteristics in dual circulating fluidized bed reactors during the CLC process. By a comparison of the outlet gas concentrations with the measured data, the CSD drag model can obtain a more reasonable prediction than the Ergun/Wen–Yu drag model. The influence of reaction temperature and air/fuel ratio on the performance of the DCFB reactor is also evaluated.
The frequency-scanning interferometer (FSI) is an advantageous distance measurement method. We propose an FSI-based non-cooperative target distance measurement system that is combined with a ...heterodyne interferometer. The heterodyne interferometer is parallel to the FSI and can measure the vibration of the target synchronously, and the measuring result is used to correct the Doppler effect in the FSI signal. To extract the vibration accurately, a circle fitting in the Lissajous curve is used to correct the influence of the multipath interference, which may damage the vibration measurement result, especially when the target is non-cooperative. Then, with a post-processing algorithm, the distance could be obtained. Finally, the distance to a non-cooperative target located at 15 m is experimentally measured using this method, and a standard deviation of 3.39 <inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula> is obtained.
•Lateral flow nucleic acid biosensor was constructed for rapid detection of microRNAs.•Three target microRNAs were all successfully detected with good linearity and sensitivity.•MicroRNAs were ...detected in the spiked serum samples with this lateral flow nucleic acid biosensor.
The authors describe a rapid and low-cost approach for multiplex microRNA(miRNA) assay on lateral flow nucleic acid biosensor (LFNAB). The principle of assay is based on sandwich-type nucleic acid hybridization reactions to produce gold nanoparticle (GNP)-attached complexes (ssDNA-microRNA-ssDNA/GNPs), which are captured and visualized on the test zone of LFNAB. By designing three different test zones on LFNAB, simultaneous detection of microRNA-21, microRNA-155 and microRNA-210 was achieved with an adding-measuring model by using GNP as visual tag. The method was challenged by testing the microRNAs in spiked serum samples with satisfied results. In our perception, the test is a particularly valuable tool for clinical application and biomedical diagnosis, particularly in limited resource settings.
•Limbic and frontoparietal networks had a greater annual aβ accumulation in aging.•The annual aβ accumulation was negatively correlated with functional connectivity.•The aβ propagation over time was ...accelerated by the connectivity of functional hubs.•Functional brain organization compensates for aβ pathology and propagation in aging.
The brain undergoes many changes at pathological and functional levels in healthy aging. This study employed a longitudinal and multimodal imaging dataset from the OASIS-3 study (n = 300) and explored possible relationships between amyloid beta (Aβ) accumulation and functional brain organization over time in healthy aging. We used positron emission tomography (PET) with Pittsburgh compound-B (PIB) to quantify the Aβ accumulation in the brain and resting-state functional MRI (rs-fMRI) to measure functional connectivity (FC) among brain regions. Each participant had at least 2 to 3 follow-up visits. A linear mixed-effect model was used to examine longitudinal changes of Aβ accumulation and FC throughout the whole brain. We found that the limbic and frontoparietal networks had a greater annual Aβ accumulation and a slower decline in FC in aging. Additionally, the amount of the Aβ deposition in the amygdala network at baseline slowed down the decline in its FC in aging. Furthermore, the functional connectivity of the limbic, default mode network (DMN), and frontoparietal networks accelerated the Aβ propagation across their functionally highly connected regions. The functional connectivity of the somatomotor and visual networks accelerated the Aβ propagation across the brain regions in the limbic, frontoparietal, and DMN networks. These findings suggested that the slower decline in the functional connectivity of the functional hubs may compensate for their greater Aβ accumulation in aging. The Aβ propagation from one brain region to the other may depend on their functional connectivity strength.
The recent discovery of possible high-temperature superconductivity in single-layer FeSe films has generated significant experimental and theoretical interest. In both the cuprate and the iron-based ...high-temperature superconductors, superconductivity is induced by doping charge carriers into the parent compound to suppress the antiferromagnetic state. It is therefore important to establish whether the superconductivity observed in the single-layer sheets of FeSe--the essential building blocks of the Fe-based superconductors--is realized by undergoing a similar transition. Here we report the phase diagram for an FeSe monolayer grown on a SrTiO3 substrate, by tuning the charge carrier concentration over a wide range through an extensive annealing procedure. We identify two distinct phases that compete during the annealing process: the electronic structure of the phase at low doping (N phase) bears a clear resemblance to the antiferromagnetic parent compound of the Fe-based superconductors, whereas the superconducting phase (S phase) emerges with the increase in doping and the suppression of the N phase. By optimizing the carrier concentration, we observe strong indications of superconductivity with a transition temperature of 65±5 K. The wide tunability of the system across different phases makes the FeSe monolayer ideal for investigating not only the physics of superconductivity, but also for studying novel quantum phenomena more generally.
Plant roots and soil microorganisms interact with each other mainly in the rhizosphere. Changes in the community structure of the rhizosphere microbiome are influenced by many factors. In this study, ...we determined the community structure of rhizosphere bacteria in cotton, and studied the variation of rhizosphere bacterial community structure in different soil types and developmental stages using TM-1, an upland cotton cultivar (Gossypium hirsutum L.) and Hai 7124, a sea island cotton cultivar (G. barbadense L.) by high-throughput sequencing technology. Six bacterial phyla were found dominantly in cotton rhizosphere bacterial community including Acidobacteria, Actinobacteria, Bacteroidetes, Planctomycetes, Proteobacteria, and Verrucomicrobia. The abundance of Acidobacteria, Cyanobacteria, Firmicutes, Planctomycetes and Proteobacteria were largely influenced by cotton root. Bacterial α-diversity in rhizosphere was lower than that of bulk soil in nutrient-rich soil, but higher in cotton continuous cropping field soil. The β-diversity in nutrient-rich soil was greater than that in continuous cropping field soil. The community structure of the rhizosphere bacteria varied significantly during different developmental stages. Our results provided insights into the dynamics of cotton rhizosphere bacterial community and would facilitate to improve cotton growth and development through adjusting soil bacterial community structure artificially.
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