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Extreme weather events do great harm to power distribution systems, causing widespread outages and huge economic losses. It is necessary to investigate the operation and recovery methods for power distribution systems against extreme weather events with small probability and high risk. Accordingly, this paper proposes a cost-optimal operation and recovery method for power distribution systems considering multiple flexible resources and logistics restrictions. The method is developed as a two-stage model to obtain the optimal cost consisting of lost load cost and network loss cost. In the first stage before the disaster, the pre-allocation of repair crews combines multiple flexible resources to cope with the upcoming extreme weather event. In the second stage after the disaster, repair crews coordinate with flexible resources to quickly recover the lost load of the system. The cooperative scheduling of repair crews and flexible resources in the method is restricted by the logistics of transportation networks. Based on the network loss, the two-stage model is formulated as a mixed integer second-order cone programming. The case study conducted on a modified IEEE 33-bus test system demonstrates the effectiveness of the method proposed in this paper.

In recent years, extreme weather events have resulted in a number of severe power outages and economic losses. It is becoming urgent to study approaches to enhance power distribution system resilience. This paper presents a two-stage optimization method for improving resilience of power distribution systems. The two-stage method is influenced by a transportation network, which considers the interdependence between traffic roads and overhead distribution lines. In the first stage, based on the Bayesian network and the Monte Carlo method, the locations of emergency stations, e.g., charging stations and repair stations are pre-positioned to improve the recovery speed of interrupted loads after disasters. Then the second stage is to co-optimize the dispatch of mobile energy storage systems and repair crews on transportation network to minimize the shedding of critical loads while considering operation constraints of power, voltage and power flow for power distribution system. The dispatch of mobile energy storage systems and repair crews are affected by the locations of emergency stations in the first stage. The route of mobile energy storage systems and repair crews on transportation network can be obtained from the results in the second stage. The proposed method is tested on a modified IEEE 33-bus distribution test system with a corresponding transportation network. Simulation results demonstrate the effectiveness of the proposed method in enhancing power distribution system resilience by pre-positioning emergency stations and co-dispatching mobile energy storage systems and repair crews.

With the gradual growth of natural gas units, the coupling between power networks and natural gas networks has deepened, and the synergistic operation between them has become more and more important. At the same time, the integration of uncertain renewable energy brings challenges to the economic and safe operation of power and natural gas interconnected systems. In order to cope with the operational risks brought by uncertain wind sources to the interconnected system, this paper adopts the method of distributionally robust chance constraints, where an ambiguity set related to the moment information of a small amount of historical wind power forecast error data is attained in a data-driven way. Then the chance constrained problem is transformed into a formation that is easily solved. For different situations with or without a central coordinator of the two entities of electricity and gas, this work respectively gives the solution steps based on the relaxed alternating direction method of multipliers. In the case of no coordinator, this paper particularly presents the convergence performance when the exchange of information has a packet loss rate during iterative calculation processes. The simulation results show that compared with the method of traditional Gaussian chance constrained optimization and symmetrical distributionally robust chance constrained optimization, the moment-based distributionally robust chance constrained optimization can achieve a lowest probability of chance constraint violation at the expense of energy dispatch costs. In addition, compared with the traditional alternating direction method of multipliers, the relaxed alternating direction method of multipliers can achieve the nearly same energy dispatch costs with a smaller number of iterations. It is also found that the packet loss of the early iteration process may be the main factor that has a degradation impact on the convergence process rather than the nominal loss probability.

With the increasing attention on Cyber Physical System (CPS) and Distributed Energy Resource (DER), the Cyber Physical Microgrids (CPM) has become a hot topic. However, how to synchronize the simulation time between the CPM co-simulation testbed is a difficult problem. To solve it, a co-simulation testbed for microgrids is established by considering TrueTime, a MATLAB/Simulink-based toolbox. Cases of a microgrid system using distributed economical control strategy are tested on this testbed. Simulation results show the influence of packet loss and bandwidth occupation, which prove the validity of this testbed.

A common belief in power system optimization is that privacy preservation can be enabled by implementing distributed dispatch algorithms. To solve the node based DC optimal power flow (OPF) problem with limited communication resources in a distributed way, this study proposes a communicationcensoring strategy (CCS) to reduce unnecessary communiation cost by using alternating direction method of multipliers (ADMM). Out of further privacy concern, dual consensus is formulated by sharing Lagrangian multipliers associated with coupling constraints between the coupled adjacent buses rather than phase angles that are usually shared. The communication mechanism considered here is censored which judges whether the difference between the latest variables and the previously transmitted counterpart has reached a well-designed censoring function. Though CCS may slow down the optimizaton process, it reduces the communication cost effectively. A simple numerical example illustrates inherent tradeoffs between commnication cost and number of iterations.

Background The ideal emergency cricothyroidotomy technique remains a topic of ongoing debate. This study aimed to compare the cannula-to-Melker technique with the scalpel-bougie technique and determine whether yearly training in cricothyroidotomy techniques is sufficient for skill retention. Methods We conducted an observational crossover bench study to compare the cannula-to-Melker with the scalpel-bougie technique in a porcine tracheal model. Twenty-eight anesthetists participated. The primary outcome was time taken for device insertion. Secondary outcomes were first-pass success rate, incidence of tracheal trauma, and technique preference. We also compared the data on outcome measures with the data obtained in a similar workshop a year ago. Results The scalpel-bougie technique was significantly faster than the cannula-to-Melker technique for cricothyroidotomy (median time of 45.2 s vs. 101.3 s; P = 0.001). Both techniques had 100% success rate within two attempts; there were no significant differences in the first-pass success rates and incidence of tracheal wall trauma (P > 0.999 and P = 0.727, respectively) between them. The relative risks of inflicting tracheal wall trauma after a failed cricothyroidotomy attempt were 6.9 (95% CI 1.5–31.1), 2.3 (95% CI 0.3–20.7) and 3.0 (95% CI 0.3–25.9) for the scalpel-bougie, cannula-cricothyroidotomy, and Melker-Seldinger airway, respectively. The insertion time and incidence of tracheal wall trauma were lower when the present data were compared with data from a similar workshop conducted the previous year. Conclusions This study supports the use of a scalpel-bougie technique for cricothyroidotomy by anesthetists and advocates a yearly training program for skill retention.

A previously healthy 32 year old man presented with a three month history of multiple well defined annular concentric plaques with slightly raised scaly borders on his scalp, forehead, right chest, back, left forearm, right groin, and thighs, with mild pruritis (fig 1). He had no associated fever, malaise, headache, or arthralgia. He reported having unprotected sexual intercourse with several female partners over the last year. No lesions were observed on the mucosal surfaces, palms, or soles. He …

Lithium-ion capacitors (LICs) are emerging energy storage devices that integrate the high energy density of lithium-ion batteries with the high-power density of supercapacitors. However, their practical performance is severely limited by the sluggish reaction kinetic for battery-type anodes. To address this issue, we propose an electrostatic self-assembly strategy for fabricating perovskite-type FeMnO3 microspheres anchored within the carbon nanotube conductive network (FeMnO3-CNTCN) as the anode materials for LICs. In the well-interconnected 3D construction, FeMnO3 microspheres with multi-step redox reaction can provide abundant active sites for the lithium storage, while highly conductive and flexible CNT substrate ensures fast lithium-ion transport and electron transfer. Benefiting from the synergistic interplay between two components, the FeMnO3-CNTCN anode exhibits the splendid cyclability and rate performance. Furthermore, the entire LIC with FeMnO3-CNTCN anode delivers a superior energy density of 163 Wh kg−1 at a power density of 245 W kg−1, along with a capacity retention of 83% after 10,000 cycles. These results demonstrate the promising prospect of FeMnO3-CNTCN in high-performance LICs, and the proposed electrostatic self-assembly strategy opens up a chance for the facile synthesis of the composite materials in advanced energy storage.

The total photovoltaic (PV) installed capacity of China plans to increase above 56 GW by 2050 to realize the goals of carbon peak and carbon neutrality. As a result, the hosting capacity of PV in a power distribution system affects the operation performance such as the quality of voltage, power balance, stability, and frequency problems. To investigate impacts of different PV penetration levels on the voltage and feeder in a typical power distribution network, this work considers uncertainties of PV output, and a Monte Carlo-based method is employed to simulate the impacts for different PV penetration levels on a power distribution network to evaluate voltage deviation from the normalized level (0.9 to 1.1 p.u.). A typical IEEE 33-bus system is studied and the connected PVG is based on 10-min resolution historical data from California in America in 2006. Results of the studied power distribution network are showed under three different cases: underloaded, overloaded, and fully-loaded that the 33-bus system injected with a higher PV penetration causes more voltage problems on the buses as well as the main feeder utilization tends to increase when the distribution system is underloaded or overloaded.

The objective of the present study was to evaluate the combined application of measuring cystatin C (Cys-C) and hemoglobin A1c (HbA1c) levels for early renal injury in pediatric patients with type 2 diabetes. A total of 130 children with type 2 diabetes admitted to our hospital from May 2013 to July 2015 were selected. Patients were divided according to whether there was complication of renal injury. In group A (n=65), the patients had renal injury and in group B (n=65), the patients did not have renal injury. The levels of Cys-C and HbA1c in the two groups were examined. The results showed that the levels of Cys-C and HbA1c of patients in group A were significantly higher than those in group B (P

Brain dysfunction is a prerequisite for critical complications in children with hand, foot, and mouth disease (HFMD). Aquaporin 4 (AQP-4) may be involved in the pathological process of cerebral oedema and injury in children with severe and critical HFMD. This study aimed to assess the association of AQP-4 with the severity of enterovirus 71 (EV71)-associated HFMD. Children with EV71-infected HFMD were divided into a common group (clinical stage 1), a severe group (clinical stage 2), and a critical group (clinical stage 3) according to Chinese guidelines. The levels of AQP-4, interleukin-6 (IL-6), norepinephrine (NE), and neuron-specific enolase (NSE) before and after treatment were tested. Serum AQP-4, IL-6, NE, and NSE levels showed significant differences among the critical, severe, and common groups before and after treatment (P 0.01). No significant differences in AQP-4 levels in cerebrospinal fluid (CSF) were observed between the critical and severe groups before and after treatment, but the CSF AQP-4 levels in these two groups were higher than those in the common group before treatment (P 0.01). Serum AQP-4 levels, but not CSF AQP-4 levels, closely correlated with serum IL-6, NE, and NSE levels. These results suggest that the level of AQP-4 in serum, but not in CSF, is a candidate biomarker for evaluating the severity and prognosis of EV71-associated HFMD.

To investigate the potential application of nitrocellulose membrane (NCM) in water treatment, this study examined the photolysis of

With the development of power distribution networks, disturbances on its cyber part, such as information delay, modification and interrupt, may result in operation risks on relevant physical systems. Most of the current research focuses on a power system or an information system separately, but few of literatures have a deep understanding on the relationship between cyber and physical domains. Thus, it is necessary to construct a co-simulation platform to investigate the intrinsic characteristics of cyber-physical power system (CPPS). By employing OPNET and MATLAB, the interaction between a communication network and a traditional power grid can be simulated in a real-time environment. A case of cyber-physical distribution network is modified from the IEEE 14-node system, and its communication system is a simplified model, which is built on the protocol of TCP/IP. The simulation on distribution network under cyber attacks verifies the function and effectiveness of the platform, which provides a clarified view of CPPS operation mechanisms.

In this paper, a framework for dynamic stability analyses of a typical inverter-based islanded microgrid is presented. The studied microgrid consists of energy storage systems, which are controlled by two kinds of strategies, namely active/reactive power (P/Q) control and voltage/frequency (V/f) control, and photovoltaic (PV) generation, which is assumed to work in the maximum power point tracking (MPPT) mode, and constant active/reactive load. The comprehensive dynamic model of the considered microgrid is developed, based on which a bunch of small-signal models are deduced at stable operating points. Then by means of eigenvalue-theorem-based stability analysis, the relation between damping modes and state variables can be derived. Afterward, a global optimal method is implemented to improve system stability, which is based on the investigation of the controller parameters that affecting the traces of eigenvalues. The simulation results show that the improved system is more stable after suffering small disturbance of a light intensity step down and a step up.

A large amount of studies has shown that compared with sweep frequency response analysis (SFRA), impulse frequency response analysis (IFRA) is feasible for online condition monitoring of power transformer winding deformation and can increase the frequency range of analysis. At present, the frequency response curves of off-line IFRA methods are mostly solved by Fast Fourier Transform (FFT). In this paper, IFRA for detecting transformer winding deformation based on morlet wavelet transform is presented. The deformation of the winding is detected by calculating the offset between the resonance point of the frequency response curve and the anti-resonance point instead of the correlation coefficient between the frequency response curves. Three levels of axial winding deformation are simulated in a 10kV distribution transformer. The IFRA method is solved using FFT and Morlet wavelet transform, respectively, and the winding is determined by calculating the offset of the resonance points of the frequency response curve. The reliability and sensitivity of the IFRA method based on the Morlet wavelet transform are verified, and the repetitive verification is performed.