ABSTRACT
The proliferation of virtual synchronous generator (VSG) technology within series-compensated double-fed induction generator (DFIG)-based wind farms is substantially hampered by the attendant risk of subsynchronous control interaction (SSCI), resulting in a significant research deficiency on systematic control interaction analysis and the development of mitigation strategies. The paper proposes an advanced active disturbance rejection control (ADRC) framework, incorporating real-time compensation mechanisms to mitigate the inadequate suppression efficacy attributable to the VSG's diminished output impedance. Initially, the mathematical expression for the VSG output impedance is rigorously deduced, and the positive damping attributes of the VSG in relation to SSCI are elucidated from the perspective of underlying mechanistic principles. Subsequently, the suppressive mechanism of SSCI by the ADRC is revealed in the context of VSG involvement, and the consequent augmentation of SSCI attributed to PI control is systematically derived. In immediate succession, the quanta of oscillation and inductive cross-coupling are encapsulated as the system's aggregate disturbance, thereby streamlining the ADRC to its primary order configuration, permitting the utilization of an extended state observer (ESO) for the dynamic estimation of said disturbance. Furthermore, a fractional-order filter function is instituted to engineer an augmented ESO, which refines the output voltage of the grid-side converter. Concurrently, a meticulous discourse on the rectification strategy for the proposed ESO parameters and its stability ensues. Ultimately, the efficacy of the mechanism analysis, alongside the robustness of the proffered control strategy for SSCI mitigation under diverse perturbation conditions, is corroborated via impedance evaluation and time-domain simulation.
ABSTRACT
Objective To evaluate the effect of cardiopulmonary bypass (CPB) on the expression of hypothalamic nerve growth factor precursor (proNGF) and the influence of hypothalamic proNGF on the sympathetic output of paraventrucular nucleus. Methods Forty-two male SD rats, aged 3-4 months, weighing 350-500 g, were divided into control group, CPB group and ischemia reperfusion (IR) group. At the end of CPB for 110 min, hypothalamus and dorsal root ganglion (DRG) were taken to measure the levels of proNGF mRNA and hypothalamic proNGF protein. Mini pipe was put into bilateral paraventrucular nucleus (PVN) and human recombination proNGF protein was injected into PVN for 7 d before the local field potentials (LFP) of RVLM was recoreded. Human recombination proNGF protein was administrated into lateral ventricle, the prior-administration-LFP of PVN and post-administration-LFP were recorded and compared. At the end of the experiment, hypothalamus was taken to measure the levels of glutamate and gammer amino butyric acid (GABA). Results Hypothalamic proNGF protein in CPB group and IR group was higher than that in the control group (P ＜ 0.05); NGF mRNA of hypothalamus and DRG in CPB and IR group were higher than those of control group (P ＜ 0.05). In PVN and RVLM, after the administration of proNGF protein, the power of delta band significantly decreased and other bands increased (P ＜ 0.05). The hypothalamic GABA level decreased (P ＜ 0.05) with no change of hypothalamic glutamate after proNGF was injected into lateral ventricle. Conclusion CPB increases the expression of proNGF in the hypothalamus contributing to the changes of hypothalamic sympathetic output.
ABSTRACT
Macular telangiectasia type 2 (MacTel type 2) is a kind of disease that characterized by the dilation of capillary in temporal macula lutea and the degeneration of neurosensory retina.It usually affects both eyes in patient aged 50 to 60.The pathophysiology of MacTel type 2 was not understood very well.With the rapid development of imaging technic and the genomic research,we have illuminated some secrets of this disease.In this article,the development of classification,fundus fluorescein angiography (FFA) and histology feature,and the characteristic of optical coherence tomography (OCT),optical coherence tomographic angiography (OCTA),macular pigment,genome about MacTel type 2 were reviewed.
ABSTRACT
Objective To investigate the effect of dopaminergic neurons of midbrain ventral tegmental area(VTA) in general anesthesia.Methods Forty adult healthy male SD rats were randomly divided into lesion group (n=20) and control group (n=20).The lesion group was given the bilateral infusion of specific dopaminergic neuron injury agent 6-OHDA in midbrain lateral VTA,while the control group received the same volume of normal saline at the same areas.The time of loss of righting reflex (LORR)loss and recovery of righting reflex(RORR)at postoperative 2 week were observed in each group.Results Compared with the control group,the LORR time in the lesion group was shortened and the RORR time was significantly prolonged under propofol-induced anesthesia (P＜0.05).However,the LORR time under the isoflurane anesthesia had no statistically significant difference between the two groups(P＞0.05),while the RORR time in the lesion group was increased(P＜0.05).Conclusion Dopaminergic neurons in midbrain VTA might play different roles in the induction and recovery of different general anesthetics.
