In Eriocheir sinensis aquaculture, crabs feeding on an artificial diet without steroid hormones available in ice-fresh fish or snails show delayed ovarian maturation and late listing. Icariin (ICA), a safe plant-derived monomer compound, can effectively promote estradiol (E 2) synthesis and ovarian development in mammals, but its effect in crustaceans has not been reported. We investigated the effects of ICA on estrogen synthesis, vitellogenesis, and oocyte development in Chinese mitten crabs fed with one of four diets containing 0, 50, 100, and 200 mg/kg ICA, respectively, for 8 weeks. Results showed that vitellogenin (VTG) contents, gonadosomatic indexes (GSIs), and oocyte volumes in ICA50 and ICA 100 crabs were significantly higher than those in the control. The highest upregulated expression of VTG in hepatopancreases and ovaries was detected in ICA100 crabs. Hemolymph E 2 contents were also significantly increased in ICA100 crabs. Enzyme-linked immunosorbent assay (ELISA) and western blot analysis indicated that the increase in E 2 concentrations was attributable to an elevation in aromatase protein levels in ovaries through the cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA)/cAMP response element binding (CREB) protein pathway. These findings suggest that ICA could serve as a natural additive to resolve the problem of delayed ovarian maturation of crabs raised in ponds.

A transformer is the most widely used equipment in power systems to transfer energy from one circuit to another. For real-time electromagnetic transient simulation, this paper presents a digital hardware emulation of the power transformer on a field programmable gate array. The linear model of the transformer is based on the admittance matrix approach. Detailed real-time modeling of the transient nonlinearities, including hysteresis phenomena, is carried out based on the Preisach theory. The nonlinear solution in real time is undertaken using a full Newton iteration. All the hardware modules for the transformer emulation were developed in VHDL. The model is fully parallelized and pipelined to achieve the lowest latency and the smallest hardware resource consumption. Real-time results on the oscilloscope are compared with off-line results from the ATP software.

A detailed power transformer electromagnetic transient model would help in accurately predicting transient stresses and formulating adequate protection strategies in power systems. This paper presents a real-time nonlinear high-resolution magnetic equivalent circuit (HR-MEC) based transformer model on the field-programmable gate array for hardware-in-the-loop simulation. This model is inspired by the mesh generated in finite-element method (FEM) tools to depict the major flux paths in the transformer. All of the major nonlinear phenomena such as saturation, hysteresis, and eddy currents are captured in the transformer hardware emulation whose modules were developed in a 32-b floating point precision VHDL. The developed HR-MEC model and nonlinear numerical solution have been fully parallelized in hardware to achieve the lowest latency in the real-time implementation. The hysteresis in the transformer core is modeled using Preisach theory, and eddy currents are incorporated using a frequencydependent network. The real-time results are validated using 3-D FEM analysis in JMAG software.

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