A Distribution Network Reconfiguration and Islanding Strategy

With the development of Smart Grid, the reliability and stability of the power system are significantly improved. However, a large-scale outage still possibly occurs when the power system is exposed to extreme conditions. Power system blackstart, the restoration after a complete or partial outage is a key issue needed to be studied for the safety of power system. Network reconfiguration is one of the most important steps when crews try to rapidly restore the network. Therefore, planning an optimal network reconfiguration scheme with the most efficient restoration target at the primary stage of system restoration is necessary and it also builds the foundation to the following restoration process. Besides, the utilization of distributed generators (DGs) has risen sharply in the power system and it plays a critical role in the future Smart Grid to modernize the power grid. The emerging Smart Grid technology, which enables self-sufficient power systems with DGs, provides further opportunities to enhance self-healing capability. The introduction of DGs makes a quick and efficient restoration of power system possible. In this thesis, based on the topological characteristics of scale-free networks and the Discrete Particle Swarm Optimization (DPSO) algorithm, a network reconfiguration scheme is proposed. A power system structure can be converted into a system consisting of nodes and edges. Indices that reflect the nodes’ and edges’ topological characteristics in Graph Theory can be utilized to describe the importance of loads and transmission lines in the power system. Therefore, indices like node importance degree, line betweenness centrality and clustering coefficient are introduced to weigh the importance of loads and transmission lines. Based on these indices, an objective function which aims to restore as many important loads and transmission lines as possible and also subjected to constraints is formulated. The effectiveness of potential reconfiguration scheme is verified by Depth First Search (DFS) algorithm. Finally, DPSO algorithm is employed to obtain the optimal reconfiguration scheme. The comprehensive reconfiguration scheme proposed by my thesis can be the theoretical basis for the power grid dispatchers. Besides, DGs are introduced in this thesis to enhance the restoration efficiency and success rate at the primary stage of network restoration. Firstly, the selection and classification principle of DGs are introduced in my thesis. In addition, the start sequence principle of DGs is presented as a foundation for the following stability analysis of network restoration with DGs. Then, the objective function subjected to constraints that aims to restore as many important loads as possible is formulated. Based on the restoration objective, islands that include part of important and restorable loads are formed because the DGs’ capacity cannot ensure an entire restoration of the outage areas. Finally, DPSO is used to obtain the optimal solution of islanding strategy and the state sequence matrix is utilized to represent the solution space. It is believed that this work will provide some useful insight into improving the power system resiliency in the face of extreme events such as natural or man-made disasters

A Case-Control Study between Gene Polymorphisms of Polyunsaturated Fatty Acid Metabolic Rate-Limiting Enzymes and Acute Coronary Syndrome in Chinese Han Population

The purpose of this study is to analyze the relationship between the polymorphisms of fatty acid desaturase 1 (FADS1), fatty acid desaturase 2 (FADS2), and elongation of very long-chain fatty acids-like 2 (ELOVL2) and acute coronary syndrome (ACS) in Chinese Han population. Therefore, we selected three single nucleotide polymorphisms (SNPs) from these candidate genes and genotyped them using PCR-based restriction fragment length polymorphism analysis in 249 ACS patients and 240 non-ACS subjects, as were Han Chinese ancestry. The results showed that rs174556 in the FADS1 gene is found to be in allelic association () and genotypic association () with ACS. The frequencies of rs174556 minor allele (T) in case group were obviously higher than in control group. The trans-phase gene-gene interaction analysis showed that the combined genotype of rs174556 (T/T) and rs3756963 (T/T) was associated with ACS (). And the results suggest that, for rs174556 C>T, the CT/TT genotypes were more likely to lead in ACS in subjects with hypertension after correction of all risk factors (, 95% CI, 2.216–7.126). These findings suggest that the polymorphisms of rs174556 in the FADS1 gene are very likely to be associated with ACS in Chinese Han population, especially in subjects with hypertension

TSG-6 inhibits IL-1β-induced inflammatory responses and extracellular matrix degradation in nucleus pulposus cells by activating the PI3K/Akt signaling pathway

Abstract Purpose Tumor necrosis factor (TNF)-stimulated gene-6 (TSG-6), a secreted protein associated with inflammation, is believed to possess momentous and multiple anti-inflammatory and tissue-protective properties. However, the role and potential mechanism of TSG-6 in cervical disk degeneration (CDD) are still not clear. Hence, we aimed to explore the effect of TSG-6 on CDD. Methods Quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) or enzyme-linked immunosorbent assay was applied to detect the expression level of TSG-6 and IL-1β in normal and degenerated nucleus pulposus (NP) tissues. Then, qRT-PCR and western blot were adopted to test the TSG-6 protein expression after IL-1β treatment (10 ng/mL) in human NP cells (HNPCs). After over-expressing TSG-6, qRT-PCR was also utilized to evaluate the expression of TNF-α, IL-8, and IL-6 and the synthesis of sulfated glycosaminoglycans (sGAGs), western blot to check the expression of extracellular matrix (ECM) proteins [collagen II, aggrecan, and matrix metalloproteinase-3 (MMP-3)], pain-related molecules (CGRP, calcitonin gene-related peptide; NGF, nerve growth factor; SP, substance P), and PI3K/Akt signaling pathway-related proteins. Results Briefly speaking, TSG-6 and IL-1β expression levels were significantly increased in CDD patient tissues; and IL-1β treatment could significantly increase TSG-6 expression in HNPCs. Further research revealed that, in addition to greatly promoting sGAGs synthesis, TSG-6 over-expression also inhibited TNF-α, IL-8, and IL-6 expression and ECM degradation in IL-1β-induced HNPCs. (The collagen II and aggrecan expression was up-regulated and MMP-3 expression was down-regulated.) Furthermore, over-expression of TSG-6 could decrease the levels of CGRP, NGF, and SP protein expression and activate the PI3K/Akt signaling pathway in IL-1β-treated HNPCs. Conclusion TSG-6 inhibits inflammatory responses, ECM degradation, and expression of pain-related molecules in IL-1β-induced HNPCs by activating the PI3K/Akt signaling pathway

Mitigation of power system forced oscillations based on unified power flow controller

Abstract Forced oscillations (FOs), or low-frequency oscillations (LFOs) caused by periodic, continuous, small power disturbances, threaten the security and stability of power systems. Flexible AC transmission system (FACTS) devices can effectively mitigate LFOs via stability control. We propose a novel method that mitigates FOs by shifting the resonant frequency. Based on the features of the linearized swing equation of a generator, a resonant frequency shift can be achieved by controlling the synchronous torque coefficient using a unified power flow controller (UPFC). Because of the resonance mechanism, the steady-state response of an FO can be effectively mitigated when the resonant frequency changes from the original one, which was close to the disturbance frequency. The principle is that a change in resonant frequency affects the resonance condition. Simulations are conducted in a single-machine infinite-bus (SMIB) system, and the simulation results verify that the method is straightforward to implement and can significantly mitigate FOs. The controller robustness when the resonant frequency is not accurately estimated is also analyzed in the simulations

High Performance Acetylene Sensor with Heterostructure Based on WO₃ Nanolamellae/Reduced Graphene Oxide (rGO) Nanosheets Operating at Low Temperature

The development of functionalized metal oxide/reduced graphene oxide (rGO) hybrid nanocomposites concerning power equipment failure diagnosis is one of the most recent topics. In this work, WO3 nanolamellae/reduced graphene oxide (rGO) nanocomposites with different contents of GO (0.5 wt %, 1 wt %, 2 wt %, 4 wt %) were synthesized via controlled hydrothermal method. X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), thermogravimetric analyses-derivative thermogravimetric analysis-differential scanning calorimetry (TG-DTG-DSC), BET, and photoluminescence (PL) spectroscopy were utilized to investigate morphological characterizations of prepared gas sensing materials and indicated that high quality WO3 nanolamellae were widely distributed among graphene sheets. Experimental ceramic planar gas sensors composing of interdigitated alumina substrates, Au electrodes, and RuO2 heating layer were coated with WO3 nanolamellae/reduced graphene oxide (rGO) films by spin-coating technique and then tested for gas sensing towards multi-concentrations of acetylene (C2H2) gases in a carrier gas with operating temperature ranging from 50 °C to 400 °C. Among four contents of prepared samples, sensing materials with 1 wt % GO nanocomposite exhibited the best C2H2 sensing performance with lower optimal working temperature (150 °C), higher sensor response (15.0 toward 50 ppm), faster response-recovery time (52 s and 27 s), lower detection limitation (1.3 ppm), long-term stability, and excellent repeatability. The gas sensing mechanism for enhanced sensing performance of nanocomposite is possibly attributed to the formation of p-n heterojunction and the active interaction between WO3 nanolamellae and rGO sheets. Besides, the introduction of rGO nanosheets leads to the impurity of synthesized materials, which creates more defects and promotes larger specific area for gas adsorption, outstanding conductivity, and faster carrier transport. The superior gas sensing properties of WO3/rGO based gas sensor may contribute to the development of a high-performance ppm-level gas sensor for the online monitoring of dissolved C2H2 gas in large-scale transformer oil

Design method of PID-type model predictive iterative learning control based on the two-dimensional generalized predictive control scheme

Conference Name:2012 12th International Conference on Control, Automation, Robotics and Vision, ICARCV 2012. Conference Address: Guangzhou, China. Time:December 5, 2012 - December 7, 2012.For the repetitive, cyclic or batch processes, iterative learning control is essentially a two-dimensional feedback control. By transforming the iterative learning control into a two-dimensional generalized predictive control, a new model predictive iterative leaning control scheme is proposed in this paper for the repetitive, cyclic or batch processes with both time-wise and cycle-wise dynamics. As the proportional, integral and derivative of the prediction errors are considered in the cost function, the proposed ILC scheme can be referred to as a PID-type model predictive iterative learning control (PID-MPILC). Compared with the two-dimensional model predictive iterative learning control (2D-MPILC) proposed in the previous works, the proposed PID-MPILC can provide much better control performances not only along cycle but also along time, which is illustrated by the numerical simulation. 漏 2012 IEEE

Synchronization control scheme for multi-process systems based on model predictive control

Conference Name:2013 25th Chinese Control and Decision Conference, CCDC 2013. Conference Address: Guiyang, China. Time:May 25, 2013 - May 27, 2013.Multi-process system (MPS) is an important process system for modern industry. The parallel operating subsystems may have synchronization requirements. A generalized synchronization control scheme is thus developed in this paper based on the model predictive control framework by combining a generalized synchronization cost function and the predictive cost function. The resulted control algorithm indicates that the predictive control errors of each sub-process and the predictive synchronization errors between sub-processes are used together as feedback information in the control scheme to ensure the optimal control performances of each sub-processes as well as synchronization performance, which essentially leads to a multi-input and multi-output (MIMO) control for the MPS. With a proper selection of the synchronization error functions, ratio and distance synchronization controls are conducted with the numerical simulation on an MPS consists of three sub-processes. The results clearly prove the effectiveness, robustness and flexibility of the proposed synchronization control scheme. ? 2013 IEEE

Activating PPARβ/δ Protects against Endoplasmic Reticulum Stress-Induced Astrocytic Apoptosis via UCP2-Dependent Mitophagy in Depressive Model

As energy metabolism regulation factor, peroxisome proliferator-activated receptor (PPAR) is thought to be a potential target for the treatment of depression. The present study was performed to evaluate the effects of activating PPARβ/δ, the most highly expressed subtype in the brain, in depressive in vivo and in vitro models. We observed that PPARβ/δ agonist GW0742 significantly alleviated depressive behaviors in mice and promoted the formation of autophagosomes around the damaged mitochondria in hippocampal astrocytes. Our in vitro experiments showed that GW0742 could reduce mitochondrial oxidative stress, and thereby attenuate endoplasmic reticulum (ER) stress-mediated apoptosis pathway via inhibiting IRE1α phosphorylation, subsequently protect against astrocytic apoptosis and loss. Furthermore, we found that PPARβ/δ agonist induces astrocytic mitophagy companied with the upregulated UCP2 expressions. Knocking down UCP2 in astrocytes could block the anti-apoptosis and pro-mitophagy effects of GW0742. In conclusion, our findings reveal PPARβ/δ activation protects against ER stress-induced astrocytic apoptosis via enhancing UCP2-mediated mitophagy, which contribute to the anti-depressive action. The present study provides a new insight for depression therapy

The complex interactions between novel DEHP-metabolising bacteria and the microbes in agricultural soils

The indigenous microorganisms with the ability of metabolising di-(2-ethylhexyl) phthalate (DEHP) in agricultural soils and their interactions with non-degrading microbes were revealed by DNA-based stable isotope probing coupled with molecular ecological network. Aside from the previously reported DEHP degraders (family Planococcaceae and genus Sphingobacterium), five OTUs representing bacteria affiliated with genus Brevundimona, class Spartobacteria, genus Singulisphaera, genus Dyella and class Ktedonobacteria were linked with DEHP biodegradation. The analysis of the constructed ecological network based on soil microbial communities demonstrated the negative relationships between DEHP degraders and the dominant family Oxalobacteraceae in soils. Additionally, two cultivable bacteria isolated from the same soils, Rhizobium-1 and Ensifer-1, had strong capabilities in degrading DEHP but their involvement in in situ DEHP degradation was questioned, as their DNA was not labelled with C-13 from DEHP. These findings provide deeper understanding on the indigenous DEHP-degrading communities and will benefit the remediation of phthalate esters contaminated soils. (C) 2019 Elsevier B.V. All rights reserved