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When geomagnetic storms occur, geomagnetically induced currents (GICs), as a kind of quasi-DC, flow through the transformer and cause the increase of reactive power loss ( $Q_{\mathrm {GIC}}$ ). Several mitigation actions (e.g., changing grid topology or installing blocking devices) exist that can reduce the harmful GIC effects on the grids. Making such decisions can be challenging, because the magnitude and direction of the induced geoelectric fields (IGFs) are uncertain and non-stationary. In this paper, the sensitivity of voltage and GIC to IGF is first calculated, and the joint voltage/GIC sensitivity feature space is constructed based on principal component analysis. On this basis, scenario clustering is conducted to obtain voltage/GIC sensitivity scenarios. This scenario not only reflects the uncertainty of IGF itself, but also reflects the impact of geomagnetic disturbance (GMD) on the system operation state. Combined with the structural parameters of Jiangsu power grid, the placement of blocking devices (BDs) is optimized. Compared with the constant IGF scenario and the IGF intensity scenario, the expected value of $Q_{\mathrm {GIC}}$ based on the sensitivity scenario decreases more.

Motivated by Rajan's study and existing economic reform theories (especially the lobby theory), we highlight income inequality as a driver of financial liberalisations. However, no evidence yet supports this idea. To verify this liberalisation‐induced‐by‐inequality hypothesis, the nexus of income inequality and financial liberalisations is formalised and empirically investigated in this paper. We utilise an ordered logit model with two‐way fixed effects and panel data from 91 countries to conduct the analyses. The baseline empirical results indicate that income inequality is a positive and significant determinant of financial liberalisations in aggregate and three component indicators. The results for three component indicators remain stable after a series of robustness checks, including mitigating the potential endogeneity via IV‐2SLS, Lewbel instrumental variable technique and difference within group, assessing the bias from the unobservable variables, considering the persistent and learning effects of liberalisations and the interaction effects, alternating the measures of income inequality, reducing business cycle, and using financial reforms rather financial liberalisation as independent variable. The results for aggregate liberalisations are slightly unstable in models with persistent and learning effects. Thus, liberalisation‐induced‐by‐inequality hypothesis is generally confirmed. In addition, the impacts of income inequality on financial liberalisations are widely heterogeneous across countries, the rate of change in income inequality and wealth inequality could also predict the occurrence of financial liberalisations, and the evidence that income inequality makes the poor easier access credits (i.e., Rajan's hypothesis) is found. Finally, the role is investigated of financial liberalisations in shaping banking stability, and we find that financial liberalisations can enhance growth and lower financial risks. [ABSTRACT FROM AUTHOR]

The explosion-proof performance is an important index for oil-immersed transformers. The nitrogen-sealed transformer is a new type of transformer with nitrogen gas in the upper space, which can buffer against internal stress increase caused by arc faults. However, the pressure changes in the transformer under internal faults are unclear. The authors of this study propose a method based on finite element simulation to analyze the pressure changes and the stress on the tank. First, the calculation process of arc energy and the pressure of the bubbles caused by the arc are derived. Second, the dynamic pressure wave propagation model and acoustic-solid coupling model are established. Last, the finite element simulation model is built to analyze the pressure characteristics. Taking the winding turn-to-turn and phase-to-phase short circuit faults as the analysis situations, the pressure changes in the 110 kV/20 MVA nitrogen-sealed transformer are simulated. Due to the pressure wave refraction and reflection, the pressure changes show oscillatory characteristics with time after the occurrence of an internal short circuit fault. The pressure wave travels from the arc fault position to the periphery. Compared to the conventional transformer, the pressure changes with slower variations under an internal short circuit fault and the tank suffer less stress, which indicates that the nitrogen-sealed transformer is more effective in the explosion-proof performance. [ABSTRACT FROM AUTHOR]

Haemangiomas (HAs) are prevalent vascular endothelial cell tumours. With respect to the possible involvement of HIF‐1α in HAs, we have explored its role in haemangioma endothelial cell (HemEC) proliferation and apoptosis. shRNA HIF‐1α and pcDNA3.1 HIF‐α were manipulated into HemECs. HIF‐α, VEGF, and VEGFR‐2 mRNA and protein levels were assessed by qRT‐PCR and Western blotting. Cell proliferation and viability, cell cycle and apoptosis, migration and invasion, and ability to form tubular structures were assessed by colony formation assay, CCK‐8, flow cytometry, Transwell assay, and tube formation assay. Cell cycle‐related protein levels, and VEGF and VEGFR‐2 protein interaction were detected by Western blot and immunoprecipitation assays. An Haemangioma nude mouse model was established by subcutaneous injection of HemECs. Ki67 expression was determined by immunohistochemical staining. HIF‐1α silencing suppressed HemEC neoplastic behaviour and promoted apoptosis. HIF‐1α facilitated VEGF/VEGFR‐2 expression and the VEGF had interacted with VEGFR‐2 at protein ‐ protein level. HIF‐1α silencing arrested HemECs at G0/G1 phase, diminished Cyclin D1 protein level, and elevated p53 protein level. VEGF overexpression partially abrogated the effects of HIF‐1α knockdown on inhibiting HemEC malignant behaviours. Inhibiting HIF‐1α in nude mice with HAs repressed tumour growth and Ki67‐positive cells. Briefly, HIF‐1α regulated HemEC cell cycle through VEGF/VEGFR‐2, thus promoting cell proliferation and inhibiting apoptosis. [ABSTRACT FROM AUTHOR]

Diabetic cardiomyopathy (DCM) is a common complication in patients with diabetes, and ultimately leads to heart failure. Endoplasmic reticulum stress (ERS) induced by abnormal glycolipid metabolism is a critical factor that affects the occurrence and development of DCM. Additionally, the upregulation/activation of silent information regulation 2 homolog‐1 (SIRT1) has been shown to protect against DCM. Tanshinone II A (Tan IIA), the main active component of Salviae miltiorrhizae radix et rhizome (a valuable Chinese medicine), has protective effects against cardiovascular disease and diabetes. However, its role and mechanisms in diabetes‐induced cardiac dysfunction remain unclear. Therefore, we explored whether Tan IIA alleviates ERS‐mediated DCM via SIRT1 and elucidated the underlying mechanism. The results suggested that Tan IIA alleviated the pathological changes in the hearts of diabetic mice, ameliorated the cytopathological morphology of cardiomyocytes, reduced the cell death rate, and inhibited the expression of ERS‐related proteins and mRNA. The SIRT1 agonist inhibited the activities of glucose‐regulated protein 78 (GRP78). Furthermore, the opposite results under the SIRT1 inhibitor. SIRT1 knockdown was induced by siRNA‐SIRT1 transfection, and the degree of GRP78 acetylation was increased. Cumulatively, Tan IIA ameliorated DCM by inhibiting ERS and upregulating SIRT1 expression. [ABSTRACT FROM AUTHOR]

As networking systems have become more complex and expensive, hands-on experiments based on networking simulation have become essential for teaching the key computer networking topics to students. The simulation approach is the most cost effective and highly useful because it provides a virtual environment for an assortment of desirable features such as modeling a network based on specific criteria and analyzing its performance under different scenarios with no cost. In this paper, we present our approach to develop an OPNET simulation networking laboratory that complements classroom lectures. Our simulation labs emphasize the understanding of the dynamics of network protocols instead of configuration and management. Students learn, through these experiments, a wide range of networking aspects including the design and the limitations of protocols, simulation and performance evaluation techniques, interpretation of data and packet analysis. Furthermore, we try to ensure that labs contain some extension or development of the topic beyond the lecture/reading and provide students additional active learning opportunities to discover knowledge. We have been using OPNET simulation in an introductory computer networks course for the past three years. Feedback from the students has been very positive. Overwhelmingly, students have indicated that the OPNET labs help them better understand the intricate details of actual networking protocols, and they generally indicate that they enjoy these labs as well. In summary, students benefit from the OPNET simulation laboratory in the following three ways. First, the OPNET simulation labs reinforce the networking theory taught by regular lectures. Second, the open design of the labs encourages active learning. Third, students gain the knowledge of modeling and simulation techniques for performance evaluation of networking systems. This active learning approach gives students experience in the subtleties of the design of a complex system, as well as prepares them for the networking industry. (Contains 7 figures and 1 table.)

Power transformer is one of the most important equipment in power system. In order to predict the potential fault of power transformer and identify the fault types correctly, we proposed a transformer fault intelligent diagnosis model based on chemical reaction optimization (CRO) algorithm and relevance vector machine(RVM). RVM is a powerful machine learning method, which can solve nonlinear, high-dimensional classification problems with a limited number of samples. CRO algorithm has well global optimization and simple calculation, so it is suitable to solve parameter optimization problems. In this paper, firstly, a multi-layer RVM classification model was built by binary tree recognition strategy. Secondly, CRO algorithm was adopted to optimize the kernel function parameters which could enhance the performance of RVM classifiers. Compared with IEC three-ratio method and the RVM model, the CRO-RVM model not only overcomes the coding defect problem of IEC three-ratio method, but also has higher classification accuracy than the RVM model. Finally, the new method was applied to analyze a transformer fault case, Its predicted result accord well with the real situation. The research provides a practical method for transformer fault intelligent diagnosis and prediction.

Atmospheric cold plasma jets with various configurations have drawn intense interests in diverse applications, such as surface modification and endoscopic applications. In this paper, a long and ultra-flexible micro-sized cold plasma jet generator is presented and its characteristics are analyzed. The generator mainly consists of two concentric silicone tubes with the inner one acting as the gas channel and the outer one acting as insulating layer of heat and high voltage. Gold thin film was sputtered on the circular surface of inner tube to work as the electrode as well as separation layer of ultraviolet radiation. Electrical, optical and thermal characteristics of this generator were investigated. Cold microplasma jet can be generated and ejected to the ambient air with the length varied from 0.1 m to 2.5 m, and it can impact on the finger without electric and heat sensation. Optical emission spectra analysis indicated that reactive species like OH and O atoms were generated in the plasma. This device exhibits ultra-flexible property which can be arbitrarily bent and plugged into complex and deep environment. Localized internal surface modification of polyvinyl chloride tube using this microplasma jet was also demonstrated and the result showed that surface wettability can be greatly improved after plasma treatment. This generator shows great potential for internal surface processing, plasma endoscopic and maskless lithography applications. [ABSTRACT FROM AUTHOR]