Static voltage stability of power grids will become more sensitive to the coordinated operation of renewable energy resources (RESs) and energy storage systems (ESSes) due to their different output ...characteristics. This paper presents a generalized approach for static voltage stability evaluation under coordinated operations of wind power, PV and energy storage stations. First, a combined model for coordinated operation of stations which describes the output characteristics of active and reactive power is established. Then, the integration point of stations is optimized by modal analysis such that the most sensitive bus in the system can be located. Afterwards, the static voltage stability margin can be evaluated for load buses via impedance modulus margin index (IMMI). Furthermore, impact of penetration rates and penetration rate ratio among wind power, PV and energy storage stations on static voltage stability margin is investigated. To validate the effectiveness of proposed method, a standard IEEE 14 bus test system is studied and numerical results are presented.
To deal with the problem that uncertain parameter in Affinity Propagation (AP) clustering algorithm affects the clustering results, this paper proposes a clustering method based on AP clustering ...algorithm and Genetic Algorithm (GA) for Photovoltaic (PV) power stations. Firstly, the modeling of PV power stations is established and clustering index are determined according to the dynamic characteristics of PV power stations. Then the proposed method takes the silhouette index, which is used to evaluate the quality of the clustering result, as the fitness function of GA. The bias parameter placed on the main diagonal of the similarity matrix in the AP clustering algorithm is constantly iterated and updated until obtaining the optimization result. Finally, the studied case verifies the better clustering performance of the proposed method. The 20 PV power stations in the Taoling Substation can be simplified into three groups, reducing the complexity and calculation time for equivalent modeling.
Purpose Although superoxide dismutase (SOD) and malondialdehyde (MDA) affect Delayed Onset Muscle Soreness (DOMS), their effects are unclear in rectus femoris muscles (RFM) of rats with different ...eccentric exercise programs and time points. The purpose of this study is to investigate the effects of the various eccentric exercise programs at different time points on the SOD mRNA expression and MDA using rat as the animal model. Methods 248 male rats were randomly divided into 4 groups: control group (CTL, n = 8), once-only exercise group (OEG, n = 80), continuous exercise group (CEG, n = 80), and intermittent exercise group (IEG, n = 80). Each exercise group was divided into 10 subgroups that exercised 0.5 h, 6 h, 12 h, 24 h, 48 h, 72 h, 96 h, 120 h, 144 h, or 168 h. Rats were sacrificed and their SOD mRNA expression, and MDA concentrations of skeletal muscle tissue were measured. Results The specimen in all eccentric exercise programs showed increased RFM SOD1 mRNA expression levels at 0.5 h (P<0.05), and decreased RFM SOD3 mRNA expression at 0.5 h (P<0.05). The continuous eccentric exercise (CE) significantly enhanced muscle SOD2 mRNA level at 0.5 h (P<0.05). After once-only eccentric exercise (OE), SOD1, SOD2, and SOD3 mRNA expression significantly increased at 96 h, whereas MDA concentrations decreased at 96 h. After CE, the correlation coefficients of SOD1, SOD2, SOD3 mRNA expression levels and MDA concentrations were -0.814, -0.763, -0.845 (all P<0.05) at 12 h. Conclusion Regular eccentric exercise, especially CE could enhance SOD1 and SOD2 mRNA expression in acute stage and the SOD2 mRNA expression correlates to MDA concentration in vivo, which may improve the oxidative adaption ability of skeletal muscles.
Thick film hybrid integrated circuit is a product of thick film technology and semiconductor technology. Because of some outstanding advantages, such as high reliability and high integration, hybrid ...integrated circuit has been gradually applied to aerospace electronic equipment. The situation of unstable electrical performance caused by individual parameters exceed standard in the hybrid integrated circuit production process has seriously affected the reliability of the product. In order to improve product quality, the nondestructive testing technology has been used to analyze the cause of the failure and determine the root causes of failure. A variety of prevention and improvement measures have been taken, which greatly avoid the recurrence of similar problems. In this paper, the solid-state power controller (SSPC) that used to replace the relay's role of switching and the breaker's role of protection has been researched, the faults appeared in the production process have been classified, such as function failure partly because of the substrate crack caused by the inappropriate soldering process, the short circuit or open circuit caused by the miss of bonding wires, mistake of bonding place or subsidence of bonding wire, out-of-tolerance of the voltage accuracy caused by the deviation of thick film resistance and the devices failure caused by the wrong process or the defect of some devices. In this paper, the nondestructive testing technology has been used to detect the failure place and failure category. The test parameters and methods have been researched and analyzed to isolate the fault to the relevant parts and component. A kind of fault location algorithm method has been raised to minimize the testing damage of product, assure the overall quality and stability of products.
A Roadmap for Big Model Sha Yuan; Zhao, Hanyu; Zhao, Shuai ...
arXiv.org,
04/2022
Paper, Journal Article
Odprti dostop
With the rapid development of deep learning, training Big Models (BMs) for multiple downstream tasks becomes a popular paradigm. Researchers have achieved various outcomes in the construction of BMs ...and the BM application in many fields. At present, there is a lack of research work that sorts out the overall progress of BMs and guides the follow-up research. In this paper, we cover not only the BM technologies themselves but also the prerequisites for BM training and applications with BMs, dividing the BM review into four parts: Resource, Models, Key Technologies and Application. We introduce 16 specific BM-related topics in those four parts, they are Data, Knowledge, Computing System, Parallel Training System, Language Model, Vision Model, Multi-modal Model, Theory&Interpretability, Commonsense Reasoning, Reliability&Security, Governance, Evaluation, Machine Translation, Text Generation, Dialogue and Protein Research. In each topic, we summarize clearly the current studies and propose some future research directions. At the end of this paper, we conclude the further development of BMs in a more general view.
Two-dimensional (2D) noble-metal dichalcogenides have emerged as a new platform for the realization of versatile flat optics with a considerable degree of miniaturization. However, light field ...manipulation at the atomic scale is widely considered unattainable since the vanishing thickness and intrinsic losses of 2D materials completely suppress both resonances and phase accumulation effects. Empowered by conventionally perceived adverse effects of intrinsic losses, we show that the structured PtSe2 films integrated with a uniform substrate can regulate nontrivial singular phase and realize atomic-thick meta-optics in the presence of topological darkness. We experimentally demonstrate a series of atomic-thick binary meta-optics that allows angle-robust and high unit-thickness diffraction efficiency of 0.96%/nm in visible frequencies, given its thickness of merely 4.3 nm. Our results unlock the potential of a new class of 2D flat optics for light field manipulation at an atomic thickness.
To investigate the analgesia-related modulation of electroencephalographic activities by transcutaneous electric acupoint stimulation (EAS).
In 15 healthy human beings, 64-channel ...electroencephalogram was recorded and power spectrum analysis was employed before, during and after EAS. Non-acupoint electric stimulation was used as control. All subjects were asked to rate their sensation to painful stimulations before and after treatment.
The relative theta power near contra-lateral centro-parietal area during EAS was negatively correlated with the pain score after EAS. Similarly, the beta activity during EAS near contra-lateral prefrontal cortex, ipsi-lateral inferior frontal and temporal lobe, and ipsi-lateral occipito-parietal cortex, were all negatively correlated with pain score after EAS.
These changes might reflect a modulation of brain activity by EAS in specific areas, which were in turn involved in modulation of certain aspects of pain-signal processing.
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