With the fast growth of renewable energy, the modern power systems are transitioning to the renewable energy dominated energy systems. However, the intrinsic intermittence and volatility of renewable energy also impose considerable challenges on the power system operation. Hence, it is of great significance to accurately evaluate the renewable energy accommodation capacity (REAC) in power system so as to effectively instruct the sustainable development of renewable energy and to alleviate the ongoing operational burdens. This paper proposes a novel evaluation method of REAC in power system comprehensively considering peak and frequency regulation. First, the mechanism and cost of deep peak regulation of thermal power units are deeply analyzed, and then the frequency dynamics response is modeled explicitly and simplified effectively. Next, a synthetic interaction model of “source-network-storage” is developed with diversified generation units, network and energy storage constraints. Furthermore, a multi-objective optimization model is established considering both economic and technical issues, and a REAC evaluation method is developed by integrating an incremental capacity augment approach with the proposed multi-objective model. Finally, the proposed REAC evaluation method is tested on the modified IEEE 39-bus system, and the numerical results verify the effectiveness of the proposed method.
A new highly oxygenated polyketide derivative, trichodersine (1), together with fourteen known compounds (2‐15) were isolated from Trichoderma sp. MWTGP‐04. The structure of trichodersine (1) was established based on comprehensive spectroscopic data analysis, and biogenesis argument. The results of double culture experiments indicated that the strain exhibited potential antifungal activity. The antifungal activities of all isolated compounds were evaluated, among them compound 1 exhibited remarkable antifungal activities against Fusarium solani, Plectosphaerella cucumerina, Alternaria panax, and Aspergillus niger, with minimum inhibitory concentrations (MICs) of 4, 4, 16, and 32 μg/mL, respectively. In addition, the antifungal experiments of polyketide derivatives (1–3) disclosed that their degree of oxidation was a key factor affecting the antifungal activity.
The aim of this study was to investigate the prevalence and characteristics of resistant Klebsiella pneumoniae isolates in the pediatric setting in China. A total of 201 non-duplicate K. pneumoniae isolates were obtained from 432 pediatric inpatients suffering from respiratory tract infections. One hundred and thirty-eight K. pneumoniae isolates were determined to be extended-spectrum beta-lactamase-producers. Of all ESBL-producing isolates, 138 (100%) were resistant to piperacillin, ampicillin, cefazolin, and aztreonam, 136 (98.4%) to cefuroxime, 126 (91.2%) to ceftriaxone and co-trimoxazole, 120 (87.4%) to cefoperazone, 91 (65.8%) to ceftazidime, 78 (56.5%) to gentamicin, and 72 (52.4%) to cefepime. TEM was the main type of beta-lactamase among ESBL-producing K. pneumoniae, followed by SHV and CTX-M-1. Of the 30 isolates harboring CTX-M-producers, 53.3% co-produced TEM, 36.7% co-produced SHV, and the remaining isolates co-produced SHV and TEM. The data show that there is a high prevalence of ESBL-producing K. pneumoniae infections among pediatric inpatients in the region.
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