This study proposes a cooperative secondary voltage and frequency control strategy to reduce the number of controller updates by using an event-triggered approach. The proposed approach is applied to ...the secondary control that will offset primary control deviations in islanded microgrids with limited computation resources. The controller updating mechanism considered here is event-triggered which judges whether a certain measurement error has reached the event-triggered condition (ETC) associated with the norm of a function with a standard state. We consider two secondary control options to form an ETC, which include a centralized strategy in which an auxiliary controller would collect all agents' states, and a distributed control strategy which only require the neighboring agents information. The corresponding stability and convergence analyses are presented and simulation results for an islanded microgrid test system consisting of four distributed generators (DGs) are provided. The simulation results validate the effectiveness of the proposed control strategies and show that the proposed strategies based on an event-triggered approach can dramatically reduce controller updates.
Diabetes mellitus is a chronic metabolic condition that affects carbohydrate, lipid and protein metabolism and may impair numerous organs and functions of the organism. Cardiac dysfunction afflicts ...many patients who experience the oxidative stress of the heart. Diabetic cardiomyopathy (DCM) is one of the major complications that accounts for more than half of diabetes-related morbidity and mortality cases. Chronic hyperglycemia and hyperlipidemia from diabetes mellitus cause cardiac oxidative stress, endothelial dysfunction, impaired cellular calcium handling, mitochondrial dysfunction, metabolic disturbances, and remodeling of the extracellular matrix, which ultimately lead to DCM. Although many studies have explored the mechanisms leading to DCM, the pathophysiology of DCM has not yet been fully clarified. In fact, as a potential mechanism, the associations between DCM development and mitogen-activated protein kinase (MAPK) activation have been the subjects of tremendous interest. Nonetheless, much remains to be investigated, such as tissue- and cell-specific processes of selection of MAPK activation between pro-apoptotic vs. pro-survival fate, as well as their relation with the pathogenesis of diabetes and associated complications. In general, it turns out that MAPK signaling pathways, such as extracellular signal-regulated kinase 1/2 (ERK1/2), c-Jun N-terminal protein kinase (JNK) and p38 MAP kinase, are demonstrated to be actively involved in myocardial dysfunction, hypertrophy, fibrosis and heart failure. As one of MAPK family members, the activation of ERK1/2 has also been known to be involved in cardiac hypertrophy and dysfunction. However, many recent studies have demonstrated that ERK1/2 signaling activation also plays a crucial role in FGF21 signaling and exerts a protective environment of glucose and lipid metabolism, therefore preventing abnormal healing and cardiac dysfunction. The duration, extent, and subcellular compartment of ERK1/2 activation are vital to differential biological effects of ERK1/2. Moreover, many intracellular events, including mitochondrial signaling and protein kinases, manipulate signaling upstream and downstream of MAPK, to influence myocardial survival or death. In this review, we will summarize the roles of ERK1/2 pathways in DCM development by the evidence from current studies and will present novel opinions on "differential influence of ERK1/2 action in cardiac dysfunction, and protection against myocardial ischemia-reperfusion injury".
Sepsis-associated encephalopathy (SAE) frequently encounters patients who are in intensive care units and ∼70% of patients with severe systemic infection. However, due to the unclear pathological ...mechanisms of SAE, the desease-modifying drug is still lack. Here, we aimed to explore whether the flavonoid components extracted from CCL (CCLF) seeds possess protective effects on SAE animals, and systematically evaluate the transcriptomic alteration (in the hippocampus) after CCLF treatment on SAE animals employing RNA sequencing. We observed that CCLF improved the brain’s learning and memory abilities and the structural integrity of BBB using cecal ligation and puncture (CLP)-induced SAE animal models, evaluated by behavioral test and tissue examination of animals respectively. RNA sequencing results showed that CCLF treatment reverses SAE-induced transcriptomic alteration in the hippocampus. Moreover, CCLF also dramatically relieved inflammatory (such as TNF-α, IL-2, and IL-6) and oxidative (MDA and SOD activity) stresses, and inhibited SAE-induced neuron apoptosis in brain tissues. More importantly, CCLF restored the PI3K/AKT signaling pathway and then induced the Nrf2 nuclear translocation to drive HO-1 expression both in vitro and in vivo. LY294002, an inhibitor of PI3K, obviously blocked CCLF’s functions on anti-apoptosis, anti-inflammation, and anti-oxidation in vivo, demonstrating that CCLF achieves its bioactivities in a PI3K/AKT signaling dependent manner. Altogether, CCLF exhibits remarkable neuro-protective function and may be a promising candidate for further clinical trials for SAE treatment.
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•CCLF seed flavonoids (CCLF) improved learning, memory, and BBB integrity in SAE animal models.•RNA sequencing revealed CCLF reversed SAE-induced hippocampal transcriptomic changes.•CCLF showed potent anti-inflammatory and antioxidant effects, reducing cytokines and oxidative markers.•CCLF inhibited SAE-induced neuron apoptosis in brain tissues.•CCLF restored PI3K/AKT signaling, promoting Nrf2 nuclear translocation and HO-1 upregulation.
In offshore wind farms, reignition overvoltages are usually caused by switching-off operations of vacuum circuit breakers, which degrade the insulation of power equipment, especially transformers. ...This paper proposes a new quantitative evaluation method of overvoltage suppression measures comprehensively considering three main indicators, which include the amplitude, steepness and reignition number. Based on the quantitative evaluation results, an improved suppression measure against high-steepness reignition overvoltages is developed. Firstly, high-frequency transient models of main components of a typical wind farm are developed in PSCAD/EMTDC. Then the stochasticity of opening instants is considered, and three main indicators are extracted for comprehensively analyzing the transient characteristics of reignition overvoltages. Subsequently, a quantitative evaluation is performed to analyze the effectiveness of different suppression measures, which involves surge arresters, RC snubbers and smart chokes with different properties and installation positions. Results show that a new combination of a surge arrester and a smart choke is capable of providing sufficient protection against a high-amplitude, high-steepness and severe-reignitions overvoltage. This research can provide a new overvoltage suppression solution for the insulation coordination of medium-voltage systems in offshore wind farms.
The effect of aeration on the performance of docosahexaenoic acid (DHA) production by Schizochytrium sp. was investigated in a 1,500-L bioreactor using fed-batch fermentation. Six parameters, ...including specific growth rate, specific glucose consumption rate, specific lipid accumulation rate, cell yield coefficient, lipid yield coefficient, and DHA yield coefficient, were used to understand the relationship between aeration and the fermentation characteristics. Based on the information obtained from the parameters, a stepwise aeration control strategy was proposed. The aeration rate was controlled at 0.4 volume of air per volume of liquid per minute (vvm) for the first 24 h, then shifted to 0.6 vvm until 96 h, and then switched back to 0.4 vvm until the end of the fermentation. High cell density (71 g/L), high lipid content (35.75 g/L), and high DHA percentage (48.95%) were achieved by using this strategy, and DHA productivity reached 119 mg/L h, which was 11.21% over the best results obtained by constant aeration rate.
With the rapid applications of communication technology, the hierarchical control of microgrids is threatened by unprecedented cyber attacks and faults. Current researches seldom study the impact on ...the control of cyber failures and their defense strategies. In this research, an economic control method modified from the traditional droop control is proposed. It requires distributed generators (DGs) to exchange corresponding information through a communication network, which may face potential risks of false data injection attacks (FDIAs). To tackle it, an attack-resilient method (ARM), modified from the weighted mean subsequence reduced (WMSR) algorithm, is proposed. It is proved that the successful attack-resistance and convergence performance require the communication topology to satisfy (<inline-formula> <tex-math notation="LaTeX">\boldsymbol r+1 </tex-math></inline-formula>)-robust, using the graph theory. By employing the TrueTime2.0 toolbox of MATLAB/Simulink, simulations of two microgrid test systems are performed. Results verify the feasibility and effectiveness of the proposed method on economic control under FDIAs.
Herein, we define the role of ferroptosis in the pathogenesis of diabetic cardiomyopathy (DCM) by examining the expression of key regulators of ferroptosis in mice with DCM and a new ex vivo DCM ...model. Advanced glycation end-products (AGEs), an important pathogenic factor of DCM, were found to induce ferroptosis in engineered cardiac tissues (ECTs), as reflected through increased levels of Ptgs2 and lipid peroxides and decreased ferritin and SLC7A11 levels. Typical morphological changes of ferroptosis in cardiomyocytes were observed using transmission electron microscopy. Inhibition of ferroptosis with ferrostatin-1 and deferoxamine prevented AGE-induced ECT remodeling and dysfunction. Ferroptosis was also evidenced in the heart of type 2 diabetic mice with DCM. Inhibition of ferroptosis by liproxstatin-1 prevented the development of diastolic dysfunction at 3 months after the onset of diabetes. Nuclear factor erythroid 2-related factor 2 (NRF2) activated by sulforaphane inhibited cardiac cell ferroptosis in both AGE-treated ECTs and hearts of DCM mice by upregulating ferritin and SLC7A11 levels. The protective effect of sulforaphane on ferroptosis was AMP-activated protein kinase (AMPK)-dependent. These findings suggest that ferroptosis plays an essential role in the pathogenesis of DCM; sulforaphane prevents ferroptosis and associated pathogenesis via AMPK-mediated NRF2 activation. This suggests a feasible therapeutic approach with sulforaphane to clinically prevent ferroptosis and DCM.
This study suggests that ferroptosis plays an essential role in the pathogenesis of diabetic cardiomyopathy. Sulforaphane prevents ferroptosis and associated pathogenesis via AMPK-mediated NRF2 activation. Display omitted
Abstract
A novel optimal allocation framework for photovoltaic generations in an integration system of buildings‐to‐distribution‐network using improved backtracking search optimization algorithm is ...proposed here. In the proposed framework, photovoltaic generations are optimally allocated to optimize the overall performance of a buildings‐to‐distribution‐network regarding the efficient active power usage of photovoltaic generations, the energy savings, and voltage profile improvement of distribution network. The effects of building active demand response on the photovoltaic generations' optimal allocation are considered in the proposed framework. An improved backtracking search algorithm using two new operators is developed to optimize the active power reduction factors and locations of photovoltaic generations. The test results of IEEE 33‐bus and 69‐bus systems demonstrate that the developed framework can take full advantage of photovoltaic generation power and the active demand response of buildings to coordinate the efficient active power usage of photovoltaic generations, the voltage profile improvement and energy savings of a buildings‐to‐distribution‐network. In addition, the improved backtracking search optimization algorithm converges faster than genetic algorithm, classical backtracking search optimization algorithm, and bird swarm algorithm.
The transient overvoltages in offshore wind farms caused by faults or frequent operations of electrical equipment are particularly severe. In order to classify the internal transient overvoltages in ...offshore wind farms, this research firstly proposes a feature extraction method based on sparse decomposition using alternating direction method of multipliers, which extracts the harmonic and impulsive components from transient overvoltages. Then based on the impulsive components and transient overvoltages, two identification features are constructed. One is an impulsive feature and the other one is a ratio feature between impulsive energy values and original energy values. Finally, based on the constructed features, a support vector machine is employed to identify different types of internal transient overvoltages. Extensive simulations and experiments are performed to verify the effectiveness of the proposed feature extraction method, which is also compared with the widely used conventional wavelet algorithms and the mathematical morphology. Results show the proposed feature extraction method is capable of classifying and discriminating among various types of internal transient overvoltages with a strong self-adaptive ability and an improved accuracy.
Deep learning (DL)-based models can achieve satisfactory performance in bearing and gear fault diagnosis relying on sufficient fault vibration signals. However, it is difficult to acquire adequate ...machine fault data in industrial applications. Generally, data collected in the healthy condition are massive, but rare fault samples are available. To address the diagnostic problem with few fault data, this article proposes a method, namely, multilabel cycle translating adversarial network (MCTAN). The architecture can translate healthy vibration data into auxiliary fault data. Signal-to-signal translation enables auxiliary data to be acquired based on few fault data and adequate healthy data. Then, the auxiliary data are utilized to improve the performance of DL-based fault classification approaches. Experimental results and comparative analysis indicate the superiority and robustness of the proposed method for bearing and gear fault diagnosis on widely used XJTU-SY, Case Western Reserve University (CWRU), Jiangnan University (JNU), and Southeast University (SEU) datasets. Even if the ratio of healthy data to fault data ranges from 50:1 to 300:1, the proposed MCTAN succeeds in raising the diagnosis accuracy by up to 25.87% and outperforms other comparative methods.
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