In distribution networks, the operation of two parallel transformers in small different tap positions, i.e., known as tap stagger, can provide a means of absorbing reactive power. The aggregated VAr ...absorption from many pairs of parallel transformers could help mitigate the high voltages in the upstream transmission system during periods of low demand. Considering distribution networks as reactive power support providers, this paper presents an optimal control strategy for the tap stagger to minimize the introduced network losses, as well as the tap switching operations. A genetic algorithm-based solution procedure is developed to find the optimal dispatch for the transformer tap positions in order to achieve the VAr absorption required by the transmission system. The proposed method is compared with two alternative control approaches based on the rule-based method and the branch-and-bound algorithm. Two practical U.K. distribution networks are modeled from real data and used to demonstrate the effectiveness of the proposed control strategy under different operating conditions.
On the basis of the biosynthesis of alkaloids derived from tryptophan and considering the wide use of spirooxindole in drug molecular design, a series of novel spirooxindole derivatives containing an ...acylhydrazone moiety were designed, synthesized, and first evaluated for their biological activities. The results of bioassays indicated that the target compounds possessed good activities against tobacco mosaic virus (TMV); especially compound 4, containing a tert-butyl at the benzene ring, exhibited the best antiviral activity in vitro and inactivation, curative, and protection activities in vivo (48.4%, 58 ± 0.4, 55.2 ± 2.3, and 49.7 ± 1.1% at 500 μg/mL, respectively) compared with ribavirin (38.2, 36.4 ± 0.2, 37.5 ± 0.2, and 36.4 ± 0.1% at 500 μg/mL, respectively) and harmine (44.6, 40.5 ± 0.2, 38.6 ± 0.8, and 42.4 ± 0.6% at 500 μg/mL, respectively). At the same time, these compounds exhibited fungicidal activity selectively against certain fungi; most of these derivatives exhibited >60% fungicidal activity against Physalospora piricola at 50 mg/kg. Additionally, compounds 25 and 14 displayed excellent insecticidal activities (60% motality against C. pipiens pallens at 0.25 mg/kg) even at very low concentrations.
Image segmentation has played an essential role in computer vision. The target detection model represented by YOLOv5 is widely used in image segmentation. However, YOLOv5 has performance bottlenecks ...such as object scale variation, object occlusion, computational volume, and speed when processing complex images. To solve these problems, an enhanced algorithm based on YOLOv5 is proposed. MobileViT is used as the backbone network of the YOLOv5 algorithm, and feature fusion and dilated convolution are added to the model. This method is validated on the COCO and PASCAL-VOC datasets. Experimental results show that it significantly reduces the processing time and achieves high segmentation quality with an accuracy of 95.32% on COCO and 96.02% on PASCAL-VOC. The improved model is 116 M, 52 M, and 76 M, smaller than U-Net, SegNet, and Mask R-CNN, respectively. This paper provides a new idea and method with which to solve the problems in the field of image segmentation, and the method has strong practicality and generalization value.
With the integration of intermittent renewable generation, transmission voltage problems have become more dynamic. The deployment and tuning of numbers of VAr compensators at various locations may ...not be cost-effective. This paper presents an alternative method, which utilizes existing parallel transformers in distribution networks, to provide reactive power absorption services for transmission systems with low demands. The operation of parallel transformers in small different tap positions, that is, with staggered taps, can provide a means of absorbing reactive power. The aggregated VAr absorption from many pairs of parallel transformers could be used to provide voltage support to the upstream transmission network. This paper focuses on the economic and technical analyses of using the tap staggering method. For the economic analysis, the associated costs of applying the tap staggering technique are investigated through static load-flow studies. The IEEE Reliability Test System is used to carry out the studies and the results are compared with the installation of shunt reactors. In the technical studies, the dynamic impacts of tap staggering or reactor switching on transmission voltages are analyzed. From the results, the tap staggering technique has more economic advantages than reactors and can reduce the voltage damping and overshoots during the transient states.
Co-drug, or mutual-prodrug, is a drug design approach consisting of covalently linking two active drugs so as to improve the pharmacokinetics and/or pharmacodynamics properties of one or both drugs. ...Co-drug strategy has proven good success in overcoming undesirable properties such as absorption, poor bioavailability, nonspecificity, and gastrointestine tract (GIT) side effects. In this work, we successfully developed a co-drug of 14-hydroxytylophorine, a phenanthroindolizidine derivative with remarkable antiproliferative activity, and dichloroacetate, a known inhibitor of pyruvate dehydrogenase kinase. Dichloroacetate steers tumour cell metabolism from glycolysis back to glucose oxidation, which in turn reverses the Warburg effect and renders tumour cells with a proliferative disadvantage. The obtained co-drugs retained the cytotoxicity of 14-hydroxytylophorine. However, they showed similar unselectivity towards normal cells.
The multilevel tiled map service is widely used and serves as a kind of digital infrastructure. These map tiles are usually rendered from vector data, whose update needs to walk or drive with ...professional equipment to check every point of interest. This leads to inconvenience and expensive cost in timely updating maps. Compared with vector data, aerial images are much easier and cheaper to obtain. In this article, we propose a novel multilevel map (MLM) generation framework that can automatically generate accurate and consistent maps with multiple zoom levels from aerial images. It consists of a level-aware map generator and a consistency-aware map generator. The level-aware map generator is able to generate accurate initial maps with realistic details for each zoom level. The consistency-aware map generator regards the initial maps at each zoom level as a sequence and builds the connection between them, so as to guarantee content consistency between maps at different zoom levels. Furthermore, we collect a large-scale high-quality dataset called MLM for map generation at multiple zoom levels. Experiments on our MLM dataset show that our method outperforms the previous state-of-the-art map generation methods on both comprehensive quantitative metrics and perceptual quality.
Interoperability testing and analysis tools provide a means for achieving and assuring the integrity of multivendor intelligent electronic devices (IEDs) data exchanges. However, the testing and ...analysis are very time consuming and error prone, and these problems worsen when a substation becomes large and complex during the engineering process, commission, replacement, maintenance, and extension. To address this challenge, this paper presents a virtual digital substation test system (VDSTS) with interoperability analysis tools for assessing and identifying the engineering challenges for the multiple-vendors digital substation. This VDSTS consists of three parts: (i) A virtual digital substation modelling for generating real-time digital substation primary plant operation and fault conditions, (ii) a standard IEC 61850-based substation protection, automation, and control (PAC) system architecture with multivendor IEDs and bay solutions, and (iii) multivendor Substation Configuration description Language (SCL) tools and in-house built data visualisation tool. The study focuses on the interoperability testing of sampled values (SV), generic object-oriented substation events (GOOSE), and manufacturing message specification (MMS) communication services, as defined in IEC 61850. The main issues identified are compatibility issues of SCL tools, protocol implementation issues, different information models, and application limitations. The outcomes will help utilities to reduce the risks associated with the general rollout of digital substations.
Qixue Shuangbu prescription (QSP) has been used for the treatment of chronic heart failure (CHF) with remarkable curative effect. Processed QSP (PQSP) could significantly improve the treatment of CHF ...after traditional Chinese medicine (TCM) processing. This study elucidated the underlying efficacy enhancement mechanism of QSP after TCM processing for treating CHF in vitro and in vivo. The injury of rat cardiomyoblast H9c2 cells was induced by anoxia/reoxygenation to mimic CHF state in vitro. Sixty Sprague-Dawley rats were used to established CHF model by intraperitoneally injecting doxorubicin (the accumulative dose 15 mg/kg). Biochemical examinations were performed in serum and cellular supernatant, respectively. Cardiac functions and histopathological changes were evaluated in CHF model rats. The protein and mRNA levels of ERK1/2, Bcl-2, Bax and Caspase-3 were evaluated by Western blot and RT-PCR, respectively. All above results of low dose crude QSP-treated group (L-CQSP), high dose CQSP-treated group (H-CQSP), low dose PQSP-treated group (L-PQSP), high dose PQSP-treated group (H-PQSP) were compared to systematically explore correlations between TCM processing and the efficacy enhancement for treating CHF of PQSP. Compared with the model group, the L-CQSP group showed significant improvement in cardiac function at 8th weeks, while no significant improvement in cardiomyocyte apoptosis and fibrosis. Both H-CQSP, L-PQSP and H-PQSP exerted beneficial therapeutic effects in injured H9c2 cardiomyocytes and CHF model rats. L-PQSP and H-PQSP significantly increased cell viability and the activity of SOD, decreased the activities of LDH, MDA and NO, up-regulated the expression of ERK1/2 and Bcl-2, down-regulated the expression of Bax and Caspase-3 compared to the same dosage of CQSP. The efficacy enhancement mechanism of PQSP after TCM processing for treating CHF was directly related to the regulation of ERK/Bcl-2/Bax/Caspases-3 signaling pathway.
•The mechanisms of CQSP and PQSP in treating CHF in vitro and in vivo was elucidated for the first time.•PQSP significantly up-regulated the expression of ERK1/2 and Bcl-2, down-regulated the expression of Bax and Caspase-3 compared to CQSP.•PQSP displayed better anti-CHF effect than CQSP by regulation of ERK/Bcl-2/Bax/Caspases-3 signaling pathway.
To mitigate the low frequency problem in a transmission system in an event of a power station failure or during low renewable generation production, UK National Grid (NG) Electricity System Operator ...has balancing mechanism in place with generators to provide temporary extra power, or with large energy users to reduce load demand or so call fast reserve services. This paper presents an alternative method to aggregately control the existing distribution network primary on load transformer tap changers as a voltage-led customer load active service. The main benefits of the proposed method are (i) to unlock the distribution network load demand flexibility without causing any negative impact on customers, and (ii) to provide the lowest cost of fast reserve service from a distribution network to transmission network. In this paper an optimal control strategy based on genetic algorithm is proposed and developed to achieve an optimized voltage-led customer load active service with the aim of finding the optimal dispatch of on load transformer tap changers by minimizing each transformer tap switching operation as well as network losses. Two practical 102 buses and 222 buses UK distribution networks have been modelled and used to demonstrate and compare the effectiveness of the proposed control methods under different operating conditions. The performances of the proposed method are also compared with both the rule-based and the branch-and-bound methods. The results show that the proposed optimal control strategy based on the genetic algorithm is more effective by achieving more accuracy and a faster solution for a large distribution network than other two methods. These are important findings as the fast reserve service by transmission network requires the accuracy of the load demand reduction delivery within 2 minutes.
Phenanthroindolizidines are naturally occurring alkaloids mainly isolated from different species of Asclepiadaceae. These alkaloids are characterized by an excellent anticancer activity against a ...very wide range of cancerous cell lines including those who are multi drug resistant. Nevertheless, phenanthroindolizidines are associated with sever neurotoxicity that prevented any candidate from this family to pass the clinical trials. A number of boron-based analogues of (R)-6-O-desmethylantofine have been synthesised. Their physochemical properties were evaluated, same as their in-vitro antiproliferative activity. The pinacol boronate ester derivative (3) showed interesting cytotoxicity against a panel of cancerous cell lines attested by a cancer cell growth-inhibitory potency (GI50) as low as 30 nM.
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