Dynamic equivalence can not only largely reduce the system size and the computation time but also stress the dominant features of the system [1]-[3]. This paper firstly recommends the basic concept of dynamic equivale...Dynamic equivalence can not only largely reduce the system size and the computation time but also stress the dominant features of the system [1]-[3]. This paper firstly recommends the basic concept of dynamic equivalent and the status of both domestic and abroad development in this area. The most existing equivalent methods usually only deal with static load models and neglect the dynamic characteristics of loads such as induction motors. In addition, the existing polymerization method which is based on the frequency domain algorithm of induction electric machines parameters takes a long time to equivalent for the large system, then the new method based on the weighted is proposed. Then, the basic steps for dynamic equivalence with the weighted method are introduced as follows. At first, the clustering criterion of motor loads based on time domain simulation is given. The motors with similar dynamic characteristics are classified into one group. Then, the simplication of the buses of motors in same group and network is carried out. Finally, parameters of the equivalent motor are calculated and the equivalent system is thus obtained based on the weighted. This aggregation method is applied to the simple distribution system of 4 generators. Simulation results show that the method can quickly obtain polymerization parameters of generator groups and the aggregation model retains the dynamic performance of the original model with good accuracy, the active and reactive power fitting error is smaller as well.展开更多
Hemorrhage control requires hemostatic materials that are both efective and biocompatible.Among these,diatom biosilica(DBs)could signifcantly improve hemorrhage control,but it induces hemolysis(the hemolysis rate>5...Hemorrhage control requires hemostatic materials that are both efective and biocompatible.Among these,diatom biosilica(DBs)could signifcantly improve hemorrhage control,but it induces hemolysis(the hemolysis rate>5%).Thus,the purpose of this study was to explore the infuence of Ca^(2+)biomineralization on DBs for developing fast hemostatic materials with a low hemolysis rate.Here,CaCl_(2)was added to the diatom medium under high light(cool white,fuorescent lamps,67.5µmol m^(−2) s^(−1)),producing Ca-DBs-3 with a particle size of 40-50μm and a Ca^(2+)content of Ca-DBs-3 obtained from the higher concentration CaCl_(2)group(6.7 mmol L^(−1))of 0.16%.The liquid absorption capacity of Ca-DBs-3 was 30.43±0.57 times its dry weight;the in vitro clotting time was comparable to QuikClot®zeolite;the hemostatic time and blood loss using the rat tail amputation model were 36.40±2.52 s and 0.39±0.12 g,which were 40.72%and 19.50%of QuikClot®zeolite,respectively.Ca-DBs-3 showed no apparent toxicity to L929 cells(cell viability>80%)and was non-hemolysis(the hemolysis rate<2%).This study prepared Ca-DBs-3 with a rapid hemostatic efect and good biocompatibility,providing a path to develop diatom biosilica hemostatic materials.展开更多
In the present paper, we study the boundary concentration-breaking phenomena on two thermal insulation problems considered on Lipschitz domains, based on Serrin's overdetermined result, the perturbation argument, ...In the present paper, we study the boundary concentration-breaking phenomena on two thermal insulation problems considered on Lipschitz domains, based on Serrin's overdetermined result, the perturbation argument, and a comparison of Laplacian eigenvalues with different boundary conditions. Since neither of the functionals in the two problems is C^(1), another key ingredient is to obtain the global H?lder regularity of minimizers of both problems on Lipschitz domains. Also, the exact dependence on the domain of breaking thresholds is given in the first problem, and the breaking values are obtained in the second problem on ball domains, which are related to 2π in dimension 2.展开更多
In this paper,we obtain some asy mptotic behav ior results for solutions to the prescribed Gaussian curvature equation.Moreover,we prove that under a con-formal metric in R^(2),if the total Gaussian curvature is 4π,t...In this paper,we obtain some asy mptotic behav ior results for solutions to the prescribed Gaussian curvature equation.Moreover,we prove that under a con-formal metric in R^(2),if the total Gaussian curvature is 4π,the conformal area of R^(2)is finite and the Gaussian curvature is bounded,then R^(2)is a compact C^(l,α)surface after completion at∞,for anya∈(0,1).If the Gaussian curvature has a Holder decay at in-finity,then the completed surface is C^(2).For radial solutions,the same regularity holds if the Gaussian curvature has a limit at infinity.展开更多
文摘Dynamic equivalence can not only largely reduce the system size and the computation time but also stress the dominant features of the system [1]-[3]. This paper firstly recommends the basic concept of dynamic equivalent and the status of both domestic and abroad development in this area. The most existing equivalent methods usually only deal with static load models and neglect the dynamic characteristics of loads such as induction motors. In addition, the existing polymerization method which is based on the frequency domain algorithm of induction electric machines parameters takes a long time to equivalent for the large system, then the new method based on the weighted is proposed. Then, the basic steps for dynamic equivalence with the weighted method are introduced as follows. At first, the clustering criterion of motor loads based on time domain simulation is given. The motors with similar dynamic characteristics are classified into one group. Then, the simplication of the buses of motors in same group and network is carried out. Finally, parameters of the equivalent motor are calculated and the equivalent system is thus obtained based on the weighted. This aggregation method is applied to the simple distribution system of 4 generators. Simulation results show that the method can quickly obtain polymerization parameters of generator groups and the aggregation model retains the dynamic performance of the original model with good accuracy, the active and reactive power fitting error is smaller as well.
基金The work was supported by National Natural Science Foundation of China(U22A20588,82172095)Shandong Provincial Natural Science Foundation(ZR2019QD005)Qingdao Science and Technology Demonstration and Guidance Project(20-3-4-50-nsh).
文摘Hemorrhage control requires hemostatic materials that are both efective and biocompatible.Among these,diatom biosilica(DBs)could signifcantly improve hemorrhage control,but it induces hemolysis(the hemolysis rate>5%).Thus,the purpose of this study was to explore the infuence of Ca^(2+)biomineralization on DBs for developing fast hemostatic materials with a low hemolysis rate.Here,CaCl_(2)was added to the diatom medium under high light(cool white,fuorescent lamps,67.5µmol m^(−2) s^(−1)),producing Ca-DBs-3 with a particle size of 40-50μm and a Ca^(2+)content of Ca-DBs-3 obtained from the higher concentration CaCl_(2)group(6.7 mmol L^(−1))of 0.16%.The liquid absorption capacity of Ca-DBs-3 was 30.43±0.57 times its dry weight;the in vitro clotting time was comparable to QuikClot®zeolite;the hemostatic time and blood loss using the rat tail amputation model were 36.40±2.52 s and 0.39±0.12 g,which were 40.72%and 19.50%of QuikClot®zeolite,respectively.Ca-DBs-3 showed no apparent toxicity to L929 cells(cell viability>80%)and was non-hemolysis(the hemolysis rate<2%).This study prepared Ca-DBs-3 with a rapid hemostatic efect and good biocompatibility,providing a path to develop diatom biosilica hemostatic materials.
基金supported by National Natural Science Foundation of China (Grant Nos. 11625103 and 12171144)Hunan Science and Technology Planning Project (Grant No. 2019RS3016)+3 种基金supported by the National Natural Science Fund for Youth Scholars (Grant No. 12101215)Scientific Research Start-Up Funds by Hunan Universitysupported by the National Natural Science Fund for Youth Scholars (Grant No. 12101216 )the Natural Science Fund of Hunan Province (Grant No. 2022JJ40030)。
文摘In the present paper, we study the boundary concentration-breaking phenomena on two thermal insulation problems considered on Lipschitz domains, based on Serrin's overdetermined result, the perturbation argument, and a comparison of Laplacian eigenvalues with different boundary conditions. Since neither of the functionals in the two problems is C^(1), another key ingredient is to obtain the global H?lder regularity of minimizers of both problems on Lipschitz domains. Also, the exact dependence on the domain of breaking thresholds is given in the first problem, and the breaking values are obtained in the second problem on ball domains, which are related to 2π in dimension 2.
基金This research is partially supported by NSF grant DMS-1601885 and DMS-1901914. Theauthors would like to thank Dong Ye for the remark regarding the negative answer ofQuestion 1.2.
文摘In this paper,we obtain some asy mptotic behav ior results for solutions to the prescribed Gaussian curvature equation.Moreover,we prove that under a con-formal metric in R^(2),if the total Gaussian curvature is 4π,the conformal area of R^(2)is finite and the Gaussian curvature is bounded,then R^(2)is a compact C^(l,α)surface after completion at∞,for anya∈(0,1).If the Gaussian curvature has a Holder decay at in-finity,then the completed surface is C^(2).For radial solutions,the same regularity holds if the Gaussian curvature has a limit at infinity.
