Kalman-Filtering-Based Frequency Control Strategy Considering Electrolytic Aluminum Load

Traditional thermal power units are continuously replaced by renewable energies,of which fluctuations and intermittence impose pressure on the frequency stability of the power system.Electrolytic aluminum load(EAL)accounts for large amount of the local electric loads in some areas.The participation of EAL in local frequency control has huge application prospects.However,the controller design of EAL is difficult due to the measurement noise of the system frequency and the nonlinear dynamics of the EAL’s electric power consumption.Focusing on this problem,this paper proposes a control strategy for EAL to participate in the frequency control.For the controller design of the EAL system,the system frequency response model is established and the EAL transfer function model is developed based on the equivalent circuit of EAL.For the problem of load-side frequency measurement error,the frequency estimation method based on Kalman-filtering is designed.To improve the performance of EAL in the frequency control,a fuzzy EAL controller is designed.The testing examples show that the designed Kalman-filter has good performance in de-noising the measured frequency,and the designed fuzzy controller has better performance in stabilizing system frequency than traditional methods.

Optical observations of LIGO source GW 170817 by the Antarctic Survey Telescopes at Dome A,Antarctica

The LIGO detection of gravitational waves(GW) from merging black holes in 2015 marked the beginning of a new era in observational astronomy. The detection of an electromagnetic signal from a GW source is the critical next step to explore in detail the physics involved. The Antarctic Survey Telescopes(AST3),located at Dome A, Antarctica, is uniquely situated for rapid response time-domain astronomy with its continuous night-time coverage during the austral winter. We report optical observations of the GW source(GW 170817) in the nearby galaxy NGC 4993 using AST3. The data show a rapidly fading transient at around 1 day after the GW trigger, with the i-band magnitude declining from 17:23 ± 0:13 magnitude to 17:72 ± 0:09 magnitude in ~1:8 h. The brightness and time evolution of the optical transient associated with GW 170817 are broadly consistent with the predictions of models involving merging binary neutron stars. We infer from our data that the merging process ejected about ~10^(-2) solar mass of radioactive material at a speed of up to 30% the speed of light.

Comparative proteomics analyses of intraspecific differences in the response of Stipa purpurea to drought

Stipa purpurea is widely distributed along a large precipitation gradient on the Tibetan Plateau.This implies that S.purpurea from different populations may have different responses to drought stress.To explore this we compared the morphological and physiological changes of S.purpurea seedlings cultivated from seeds from Gar County and Nagqu County after 7 and 14 days of drought stress and subsequent rewatering.The results showed that S.purpurea plants from the more arid Gar area were more tolerant to drought stress than that from Nagqu.To investigate the potential mechanisms underlying this difference,we used i TRAQ quantitative proteomics technology to analyze protein dynamics in S.purpurea samples treated with 7 days of drought stress and subsequent re-watering.The results indicated that,during the process of drought and re-watering treatments,there were differentially expressed proteins in either or both S.purpurea populations.These differential proteins were divided into 24 functional categories that were mainly associated with stress response,the antioxidant system,photosynthesis,carbohydrate metabolism,and post-translational modifications.According to these results,we concluded that the molecular basis of stronger drought resistance likely lies in the specific up-regulation or higher expression of many proteins involved in stress response,the antioxidant system,post-translational modification and osmotic regulation in S.purpurea from Gar County compared with that from Nagqu.This study improves our understanding of the intraspecific differences in drought resistance within S.purpurea populations,which helps to understand the distribution of S.purpurea along the moisture gradient,as well as the effect of climate change on this species.

Lewis base catalyzed ring-expansion of isatin with 2,2,2-trifluorodiazoethane(CF3CHN2):An efficient route to3-hydroxy-4-(trifluoromethyl)quinolinones

A Lewis base catalyzed ring expansion of isatin with 2,2,2-trifluorodiazoethane(CF3 CHN2)is developed.It is characterized that the merge of tetramethylethylenediamine and CF3 CHN2 generates reactive triazene intermediates,which construct substituted 3-hydroxy-4-(trifluoromethyl)quinolinones with high efficiency.Synthetic application of the procedure is broadened by 3-trifluormethylpyrazole fused3-hydroxy-4-(trifluoromethyl)quinolinone synthesis.