Disturbance Events Research Articles

Dynamic Scheduling Optimization of Production Workshops Based on Digital Twin

Production scheduling is the key to manufacturing process decision support, which directly affects the efficiency and competitiveness of enterprises. The production process of discrete workshops is complex and changeable, and it is usually difficult to make adjustments quickly and accurately in response to disturbance events. In this paper, a workshop production scheduling method based on digital twin is proposed and applied to the manufacturing workshop of an aerospace factory. Combined with the advantages of real-time virtual real interaction fusion of digital twin technology, the dynamic scheduling problem under fault disturbance factors is studied. A high-fidelity digital twin workshop is established to realize the mapping and interaction between the real production and the virtual factory. Based on the vibration data of machine tool spindle, a fault prediction method of learning vector quantization neural network is proposed. The dynamic scheduling strategy of workshop production based on digital twin is constructed and compared with the scheduling results without digital twin under fault disturbance. The results show that the scheduling method based on digital twin can effectively deal with disturbances and improve workshop productivity. This study can be used for the application of digital twin and production scheduling in practical factories.

A Severe Hurricane Increases Carbon Dioxide and Methane Fluxes and Triples Nitrous Oxide Emissions in a Tropical Forest

Tropical cyclones (for example, hurricanes, typhoons) are expected to intensify under a warming climate, with uncertain effects on tropical forests. These ecosystems contribute disproportionately to greenhouse gas (GHG; carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O)) fluxes globally but there is high uncertainty in how these fluxes will respond to the projected increase in the frequency of severe tropical cyclones. To examine how these natural disturbance events may alter ecosystem processes in tropical forests, we studied the effects of Hurricane María (2017), a category 4 storm, on soil GHG fluxes from a forest in Puerto Rico. We also asked how environmental conditions, namely severity of tree canopy damage and topographic position, influenced spatial heterogeneity in post-hurricane soil GHG emissions. Seven months after Hurricane María, we observed an 18% increase in soil CO2 fluxes, a switch in CH4 fluxes from net consumption toward net production, and a threefold increase in N2O emissions relative to pre-hurricane fluxes. None of these fluxes were sensitive to topographic heterogeneity or the magnitude of tree canopy damage, in contrast to the marked soil GHG flux sensitivity to topography prior to the storm. Upscaling the increase in soil N2O emissions to the ecosystem level shows that greater emissions of soil N2O following hurricanes also led to high rates of nitrogen loss that, if sustained over a year, would be equivalent to 30% of estimated losses of inorganic nitrogen to runoff and groundwater. Additionally, the combined hurricane-induced increases in soil GHGs suggest a 25% increase in the contribution of soil GHG emissions from this forest to global warming, an effect that can persist for several months after the storm. Taken together, our results show that hurricane disturbance in coastal tropical forests can, at least temporarily, shift the radiative forcing of soils in these forests, exacerbating climate change.

Examining the relative influence of dispersal and competition on co-occurrence and functional trait patterns in response to disturbance

Disturbance gradients are particularly useful for understanding the relative influences of competition and dispersal. Shortly after disturbance, plant composition should be influenced more strongly by dispersal than competition; over time, this should reverse, with competition becoming more important. As such, we predicted that plant functional traits associated with high dispersal ability would be over-represented shortly after a disturbance event occurs, while those associated with high competitive ability would have increased representation as time progresses. Additionally, it has been suggested that competitive interactions may contribute to negative co-occurrence patterns; if this is the case, negative co-occurrence patterns should also increase as time-since-disturbance increases. Here, we examine how functional trait and co-occurrence patterns change over time following a herbicide-based disturbance, compared to undisturbed vegetation, in a temperate, old-field grassland dominated by herbaceous perennials. In our study system, negative co-occurrence patterns were most pronounced in disturbed plots one year after herbicide application, consistent with several lines of evidence that dispersal can strongly impact both composition and co-occurrence patterns. Over three years post-disturbance, co-occurrence patterns in disturbed plots decreased, becoming more similar to control plots. This pattern is inconsistent with the expectation that competition contributes to negative co-occurrence patterns, at least over three growing seasons. More pronounced negative co-occurrence patterns were associated with higher species evenness among plots. Functional traits related to increased dispersal (mean seed mass, and proportion of stoloniferous/rhizomatous species) and competitive ability (mean species height, and mean specific leaf area) did not differ significantly across treatments, with the exception of mean height in the third-year post-disturbance; however, the overall trajectory of this trait was inconsistent with theoretical expectations. Overall, co-occurrence patterns changed across the gradient of time-since disturbance, but not as expected; functional trait patterns (trait means, functional diversity measures) were not responsive to our experimental disturbance gradient.

Scleractinian recruits on natural and artificial substrates in temporary sediment-challenged coastal water of Bangkalan, Madura Island, Indonesia

Recruitment of coral juveniles could serve as indicator for potential of coral reef recovery and is a critical process in supporting population as well as facilitating recovery after event of disturbance. However, sediments suspended in the water column and settling on to reef surface can negatively influence the distributions and abundances of reef-building corals, including altering the settlement patterns and survival of coral larvae and new recruits. In this study, we compared the density and diversity of Scleractinian recruits on natural substrate and artificial reef (made of concrete; 2 years after deployment) in the relatively turbid water of Sepulu coastal water, Bangkalan – Madura Island, East Java. Observation of stony coral recruits were conducted in-situ at depth of 3-4 meter in two locations. At the end of the study, we identified 18 species of Scleractinians from 10 genera and 7 families; dominated by Goniopora (F. Poritidae), Galaxea (F. Euphyllidae) and Goniastrea (F. Merulinidae). There was no difference in term of species richness and composition among locations and type of substrate. However, in both locations, more recruits grown in concrete artificial reef (15.2±2.61 - 18.3±2.91 unit/m2) compared to natural substrate (4±1.25 - 4.1±1.29 unit/m2), respectively. These findings suggest that concrete artificial reef is applicable for coral reef restoration and rehabilitation in temporary turbid coastal water by providing suitable substrate for larval recruitments.

Virtual inertia control based on fast frequency response

In order to improve the inertia support of wind power system in case of load disturbance events, a control frequency response method based on Hammerstein-Neural Network (HNNFC) is proposed in this paper. First, the sliding mode control (SMC) law is designed according to the system frequency dynamic response equation. Then, the system is identified based -Hammerstein-Neural Network (HNN). Moreover, the system disturbance is designed of the ESO which is used as the compensator of the Hammerstein model to improve the fast and stable recovery performance of the system. Finally, the simulation results show that this method can not only release the active power through the rotor kinetic energy, but also improve the system stability recovery ability. The simulation can be seen that the proposed method can well reproduce the original control method. Compared with traditional control methods, the proposed method can improve the robustness ability of the wind power system.

Glacial Legacies: Microbial Communities of Antarctic Refugia.

Simple SummaryMicrobial communities in Antarctica have only recently been described with the increasing popularity and ease of genome sequencing. Using these methods, we aimed to test hypotheses of refugia using microbial communities in the McMurdo Dry Valleys of Victoria Land, Antarctica. Refugia are habitable areas that remain undisturbed during cycles of glacial expansions throughout Earth’s history. They may contain ancient lineages and unique communities worthy of conservation, as well as provide insight into the biotic history of Antarctica. We found unique microbial community assemblages from putative refugia in the McMurdo Dry Valleys indicating long-lived climax-communities in one of the harshest environments in the world. This finding corroborates the importance of glacial legacies in structuring not just the physical and geochemical environment, but also the soil microbial communities in this landscape.In the cold deserts of the McMurdo Dry Valleys (MDV) the suitability of soil for microbial life is determined by both contemporary processes and legacy effects. Climatic changes and accompanying glacial activity have caused local extinctions and lasting geochemical changes to parts of these soil ecosystems over several million years, while areas of refugia may have escaped these disturbances and existed under relatively stable conditions. This study describes the impact of historical glacial and lacustrine disturbance events on microbial communities across the MDV to investigate how this divergent disturbance history influenced the structuring of microbial communities across this otherwise very stable ecosystem. Soil bacterial communities from 17 sites representing either putative refugia or sites disturbed during the Last Glacial Maximum (LGM) (22-17 kya) were characterized using 16 S metabarcoding. Regardless of geographic distance, several putative refugia sites at elevations above 600 m displayed highly similar microbial communities. At a regional scale, community composition was found to be influenced by elevation and geographic proximity more so than soil geochemical properties. These results suggest that despite the extreme conditions, diverse microbial communities exist in these putative refugia that have presumably remained undisturbed at least through the LGM. We suggest that similarities in microbial communities can be interpreted as evidence for historical climate legacies on an ecosystem-wide scale.

The interaction between administrative jurisdiction and disturbance on public lands: Emerging socioecological feedbacks and dynamics.

Disturbance is one of the fundamental shapers of ecological communities, redistributing resources and resetting successional pathways. Human activities including resources management can influence disturbance regimes and trajectories by actively imposing or suppressing disturbance events or shaping ecosystem recovery via disturbance response. Furthermore, different management objectives may drive different disturbance responses. This suggests that the management jurisdiction to which a land parcel is assigned is likely to influence disturbance management and therefore ecological conditions within that parcel. Here, we combined two exploratory approaches to investigate this linkage. First, we used a systematic literature review to develop a typology of reported disturbance response types and strategies by federal land management agencies in the US. Second, we used Forest Inventory and Analysis (FIA) plot data in five multi-jurisdictional ecosystems containing national parks to investigate the relationship between land ownership and large disturbance occurrence and between disturbance and tree growth rate. We found that agencies vary in the diversity of disturbance response tactics they are reported to employ, and disturbance types vary in the diversity of responses reported in the literature. Disturbance occurrence varied by land ownership type across the FIA dataset, and the direction of tree growth rate was influenced by the interaction between ownership type and disturbance occurrence in two of five examined ecosystems. Although our mixed methods approach was purely exploratory and not mechanistic, our findings suggest that disturbance response is one possible route by which management regimes may influence ecological conditions. Efforts to understand and predict ecological heterogeneity across large landscapes must consider variation in the social system as a potential contributor to such patterns.

Dynamic Security Assessment For Power System Using Attribute Selection Technique

The evaluation of the dynamic security of the electrical power system after the occurrence of disturbances in the network is one of the most important tools that the control center uses to maintain the system in a safe operating mode, as well as prevent cases of system out of control and cases of complete shutdown. With the annual increase in the size of the electrical system and its distribution over a very wide geographical area, this led to a new challenge to assess dynamic security assessment (DSA), which is dealing with a huge and varied amount of data that requires processing in a very short time. To address these challenges, this study presented a new technique of artificial intelligence, which is the attribute selection technique, to reduce the size of this data and thus improve the accuracy and speed of results. This method relied on the combination of decision tree algorithms and a technique (Attribute selection) in the data obtained from the test system (IEEE-30Bus). The results of this method showed a significant reduction in the number of data used, which amounted to (45.55%) of the total data, Which led to an improvement in the classification accuracy, as the classification accuracy reached (97.27%). This reduction is very important when dealing in the online operating environment, as it saves the time necessary to reach the most accurate evaluation decision and thus issue gives a greater opportunity to take the appropriate decision in the event of disturbances and keep the electrical system in a secure state.

Investigation of Ionospheric Disturbance and Seismic Events Based on Machine Learning

Earthquakes are natural disasters that endanger human life and cause the greatest loss of property. The study of anomalous disturbance of the ionosphere, one of the pre-earthquake anomalies, will help to further study the coupling effect on the ionosphere before the earthquake. This paper focuses on the analysis of the importance and influence of various parameters inside the seismic ionosphere under earthquake conditions, constructs a classification and prediction model of seismic ionospheric anomalies based on the gradient boosting decision tree GBDT algorithm, and analyzes the pre-earthquake ionospheric data. , the results show that NmE, nHe+, foF2 and TEC are important influencing factors, which lays a certain foundation for the further study of the internal structure and parameters of the pre-earthquake ionosphere

Temperament, parenting, mental disorders, life stressors and help-seeking behavior of Asian adolescent suicide attempters: A case control study.

PurposeThe need to elucidate risk factors for adolescent suicide is urgent, as suicide consistently ranks among the top causes of death globally. Understanding suicide risk factors could inform more effective interventions. Previous studies have identified certain risk factors associated with suicide, but there is a paucity of research among adolescent and multi-ethnic Asian populations.Materials and methodsThis case-control study sampled 13-to-19-year-old Asian adolescents who had attempted suicide (N = 60) and controls (N = 58) matched by age, ethnicity and gender at group-level (73.7% female). Life stressors, temperament, parenting style, mental health conditions and help-seeking behavior were examined.ResultsAll domains of life stress apart from emerging adult responsibility were higher among cases than controls, especially home life, peer pressure and romantic relationships. Suicide attempters tended to avoid new situations, be less adaptable to changes, have a negative outlook and irregular sleep-wake cycle. Additionally, they perceived their parents to be significantly more aggressive, neglecting, rejecting and cold, while parents’ perceptions of their own parenting were only significantly different in the domain of parental neglect. Cases were more likely to exhibit disorders of disruptive behavior, eating, mood, anxiety, symptoms of schizophrenia and experience of disturbing events. Significant differences were also found for 10 out of 12 Axis II disorders, particularly borderline, depressive, and avoidant personality disorder traits. No significant case-control differences were found regarding overall rates of help-seeking.ConclusionFindings from this study may help in suicide prevention efforts through more tailored interventions.

Reliably mapping low-intensity forest disturbance using satellite radar data

In the last decades tropical forests have experienced increased fragmentation due to a global growing demand for agricultural and forest commodities. Satellite remote sensing offers a valuable tool for monitoring forest loss, thanks to the global coverage and the temporal consistency of the acquisitions. In tropical regions, C-band Synthetic Aperture Radar (SAR) data from the Sentinel-1 mission provides cloud-free and open imagery on a 6- or 12-day repeat cycle, offering the unique opportunity to monitor forest disturbances in a timely and continuous manner. Despite recent advances, mapping subtle forest losses, such as those due to small-scale and irregular selective logging, remains problematic. A Cumulative Sum (CuSum) approach has been recently proposed for forest monitoring applications, with preliminary studies showing promising results. Unfortunately, the lack of accurate in-situ measurements of tropical forest loss has prevented a full validation of this approach, especially in the case of low-intensity logging. In this study, we used high-quality field measurements from the tropical Forest Degradation Experiment (FODEX), combining unoccupied aerial vehicle (UAV) LiDAR, Terrestrial Laser Scanning (TLS), and field-inventoried data of forest structural change collected in two logging concessions in Gabon and Peru. The CuSum algorithm was applied to VV-polarized Sentinel-1 ground range detected (GRD) time series to monitor a range of canopy loss events, from individual tree extraction to forest clear cuts. We developed a single change metric using the maximum of the CuSum distribution, retrieving location, time, and magnitude of the disturbance events. A comparison of the CuSum algorithm with the LiDAR reference map resulted in a 78% success rate for the test site in Gabon and 65% success rate for the test site in Peru, for disturbances as small as 0.01 ha in size and for canopy height losses as fine as 10 m. A correlation between the change metric and above ground biomass (AGB) change was found with R2 = 0.95, and R2 = 0.83 for canopy height loss. From the regression model we directly estimated local AGB loss maps for the year 2020, at 1 ha scale and in percentages of AGB loss. Comparison with the Global Forest Watch (GFW) Tree Cover Loss (TCL) product showed a 61% overlap between the two maps when considering only deforested pixels, with 504 ha of deforestation detected by CuSum vs. 348 ha detected by GFW. Low intensity disturbances captured by the CuSum method were largely undetected by GFW and by the SAR-based Radar for Detecting Deforestation (RADD) Alert System. The results of this study confirm this approach as a simple and reproducible change detection method for monitoring and quantifying fine-scale to high intensity forest disturbances, even in the case of multi-storied and high biomass forests.

Peculiarities of the Heliospheric State and the Solar-Wind/Magnetosphere Coupling in the Era of Weakened Solar Activity

Based on the data of the solar wind (SW) measurements of the OMNI database for the period 1976–2019, we investigate the behavior of SW types, as well as plasma and interplanetary magnetic field (IMF) parameters, for 21–24 solar cycles (SCs). Our analysis shows that with the beginning of the period of low solar activity (SC 23), the number of all types of disturbed events in the interplanetary medium decreased, but the proportion of magnetic storms initiated by CIR increased. In addition, a change in the nature of SW interaction with the magnetosphere could occur due to a decrease in the density, temperature, and IMF of solar wind.

Unravelling the fabrics preserved inside early diagenetic concretions: Insights for the distribution, accumulation and preservation of organic-rich mud in the interior of epicontinental basins

Fine-grained sedimentary rocks generally undergo severe mechanical compaction during burial, which complicates the recognition of primary mudstone fabrics and associated sedimentary features. Early diagenetic concretions, however, provide a rare glimpse of primary fabrics because cement filling the pore space prevents the collapse of original grain arrangements. Hand specimens of concretions collected from the basal condensed section of the Late Jurassic-Early Cretaceous Vaca Muerta Formation (Neuquén Basin, Argentina), allow for analysis of sedimentary processes responsible for the dispersal, accumulation and burial of organic carbon-rich sediment in an epicontinental sea. Representative samples from central basin depositional localities were examined by optical, scanning electron microscopy and energy dispersive X-ray spectroscopy. Petrographic observations were complemented with palynological and organic geochemical analyses. Close examination of uncompacted fabrics reveals a significantly more complex and dynamic depositional scenario than previously assumed (suspension settling). Although many of the component grains in the studied samples were originally delivered to the sediment–water interface by suspension settling processes (i.e., marine snow, hypopycnal plumes, pumice rafts), there is substantial evidence of episodic sedimentation controlled by punctuated events of seafloor disturbance and erosion. The common presence of muddy intraclasts indicate that the seafloor was frequently reworked by bottom currents that caused the widespread distribution of organic carbon-rich sediment across distal basin depositional environments. Bottom current circulation supplied oxygen to the sediment–water interface and created suitable conditions for benthic life, contravening the assumption of bottom water anoxia as a prerequisite for organic carbon preservation. The excellent preservation state of freshwater algae (Pediastrum complex) suggests that organic matter contained inside mud composite particles can travel long distances before being deposited in distal depositional settings. Encapsulation protects organic components from mechanical/biogenic degradation and provides an anoxic microenvironment for preventing the oxidation of the organic matter contained inside of mud composite grains. The study shows that organic carbon encapsulation may be an important mechanism for organic carbon preservation in relatively energetic and non-anoxic settings, calling for a critical reappraisal of the processes responsible for the sequestration of organic carbon from the biosphere and its long-term storage in organic-rich mudstone successions.

Comparative Analysis of a DC-microgrid Incorporating Hybrid Battery/Supercapacitor Storage System Addressing Pulse Load

Renewable energy sources (RESs) have become the primary power source of microgrids with many merits. However, RESs depend on the climate (i.e., wind speed and solar irradiance), leading to intermittent power generation. Moreover, some of the particular loads, such as the pulse load, severely impact the microgrid performance. Therefore, energy storage systems (ESSs) are considered a vital solution to improve microgrid performance and overcome microgrid challenges. This paper presents a comparative analysis of the performance of a DC-microgrid incorporating a battery storage system (BSS) and a hybrid battery/supercapacitors storage system (B-SCSS). The study addressed the fluctuations of solar radiation and wind velocity on the system performance in the presence of both energy storage technologies. In addition, the sudden load disturbance is also investigated with particular attention to the pulse load. The overall microgrid components are designed and controlled based on the PI controller to enhance the system's stability. The photovoltaic and wind energy are utilized with maximum power tracking (MPPT) to get the full benefits from RESs. The B-SCSS is proposed to maintain the DC-bus voltage, load power, and frequency constant during various disturbance events. The obtained results using Matlab software prove the effectiveness of the proposed method.

A Novel Hardware-in-the-Loop Approach to Investigate the Impact of Low System Inertia on RoCoF Relay Settings

This paper presents a novel hardware-in-the-loop (HIL) approach as used to investigate the impact of the reduction in inertia on the Great Britain (GB) electrical power system with regard to rate of change of frequency (RoCoF) settings for Loss-of-Mains (LoM) protection. Furthermore, the research as presented in this paper updates, enhances, and validates a reduced model of the Great Britain transmission system, as originally developed in DIgSILENT PowerFactory by the National Grid Electricity System Operator. The enhanced model has been developed for integrated use with the OPAL-RT real-time HIL simulation toolkit and is validated against phasor measurement unit (PMU) data from actual disturbance events using novel automated interfacing between both integrated simulation platforms, PowerFactory from DIgSILENT and ePHASORSIM from OPAL-RT. The corresponding simulations show that the updated reduced model is capable of capturing the dynamic behaviour of the GB transmission system, including both local and inter-area oscillations, with satisfactory accuracy. Finally, the paper presents HIL study results with the reduced model to investigate the influence of decreasing system inertia on the response of LoM protection relays. The studies show that decreasing system inertia may have a significant impact on LoM relays using RoCoF detection, particularly relays using the legacy G59 setting of 0.125 Hz/s. Initial studies have also demonstrated the potential for a previously unrecognised interaction between system oscillations and the 500 ms operating delay, as specified in G59 and G99 Engineering Recommendations. Consequently, faster local oscillations (>1 Hz) reset the relay and decrease the sensitivity, whereas slower inter-area oscillations (<1 Hz) appear to cause the relay to overestimate the average RoCoF.

Le condizioni delle foreste italiane stanno peggiorando a causa di eventi climatici estremi? Evidenze dalle reti di monitoraggio nazionali ICP Forests - CON.ECO.FOR.

Tree defoliation and mortality are triggered in Europe by extreme climatic events that are recurring since the beginning of XXI century. Data from the ICP Forests monitoring networks reveal a general worsening of tree conditions in the last ten years, as consequence of the drought and heat waves that affected the Southern (2017) and Central Europe (2018-2019). In Italy a significant increase of defoliation and tree mortality, assessed on the extensive (Level I) monitoring network, was observed after the 2017 dry summer, which impacted mainly the broadleaved forests (beech and oak forests) in the peninsular regions. Coniferous forests of the alpine belt were severely impacted in 2021, probably because of the co-occurrence of multiple causes, involving windstorm and bark beetle attacks. Chestnut forests suffer from pest (insect and pathogen) attacks. The intensive (Level II) monitoring network provides cases of study and allows to carry out specific cause-effect studies concerning the physiological effects on the environmental impacts, as well to observe the ecological processes following the disturbing events. Defoliation caused by drought or pest attacks induces the loss of physiological defenses (namely non-structural carbohydrates), that need several years to be restored. Then, the occurrence of more frequent and repeated heat and drought waves can produce irreversible effects. In this view, the long-term forest health monitoring is key to detect the extent and direction of changes in forest structure and composition, and represents an important tool for forest conservation and management.

Intelligent Control of the Energy Storage System for Reliable Operation of Gas-Fired Reciprocating Engine Plants in Systems of Power Supply to Industrial Facilities

Gas-fired reciprocating engine plants (GREPs) are widely used in power supply systems of industrial facilities, which allows for ensuring the operation of electrical loads in case of accidents in the power system. Operating experience attests to the fact that during islanded operations, GREPs are shut down by process protections or protective relays in the event of severe disturbances. This leads to complete load shedding, which is accompanied by losses and damage to industrial facilities. Severe disturbances include the following ones: large load surges on GREPs due to one of them being switched off, the group starting of electric motors, and load shedding (more than 50%) during short circuits or disconnection of process lines. Energy storage systems (ESS) have the ability to compensate for instantaneous power imbalances to prevent GREPs from switching off. The authors of this study have developed methods for intelligent control of the ESS that allow one to solve two problems: prevention of GREPs shutdowns under short-term frequency and voltage deviations as well as preservation of the calendar and cycling lifetime of battery storage (BS) of the GREP. The first method does not require performing the calculation of adjustments of control actions for active and reactive power on the ESS online but rather determines them by the value of frequency deviations and the voltage sag configuration, which greatly simplifies the system of automatic control of the ESS. The second method, which consists in dividing the steady-state power/frequency characteristic into sections with different droops that are chosen depending on the current load of the ESS and the battery state of charge, and offsetting it according to a specified pattern, allows for preventing the premature loss of power capacity of the ESS BS.

A Framework for Assessing Resilience in Urban Mobility: Incorporating Impact of Ridesharing.

To a certain degree, the resilience of the transportation system expresses the safety of the transportation system, because it reflects the ability of the system to maintain its function in the face of disturbance events. In the current research, the assessment of the resilience of urban mobility is attractive and challenging. Apart from this, the concept of green mobility has been popular in recent years. As a representative way of shared mobility, the implementation of ridesharing will affect the level of urban mobility resilience to a certain extent. In this paper, we use a data low-intensity method to evaluate the urban traffic resilience under the circumstance of restricted car use. In addition, we incorporate the impact of ridesharing services. The research in this paper can be regarded as an evaluation framework, which can help policy makers and relevant operators to grasp the overall resilience characteristics of cities in emergencies, identify weak sectors, and formulate the best response plan. This method has been successfully applied to two cities in China, demonstrating its potential for practice. Finally, we also explored the relationship between urban traffic resilience and the pattern of population distribution. The analysis shows that population density has an impact on the level of transportation resilience. And the incorporation of ridesharing will bring an obvious increment in resilience of most areas.

Evaluation of Different Methods for Voltage Sag Source Detection

This paper compares and evaluates three different methods for voltage sag source detection. First method (method I) is based on the assumption, that the energy flow at the monitoring point increases during downstream events and decreases during upstream events. Second and third method (methods II and III) are both based on the assumption that currents measured at the monitoring point increase during downstream events and decrease during upstream events. The slope of a current-voltage trajectory is investigated in method II, while a real current component is observed within method III. Both current-based methods (II and III) require fundamental harmonic components of sampled voltages and currents, which are extracted using discrete orthogonal series expansion, such as Fourier or Walsh. Algorithms of this type are especially appropriate for studying steady-state and periodically repeating conditions. Voltage sags are, on the contrary, transient disturbance events. Thus, usage of the discussed algorithms may not be appropriate. Furthermore, criteria within methods II and III are checked for each phase individually. In the cases of asymmetrical voltage sags exact interpretation of the obtained results, therefore, might not be possible. Method I is, on the contrary, based on instantaneous values of line voltages and currents, while three-phase criterion is used. An exact interpretation of the results obtained by this method is, therefore, also possible in cases of asymmetrical voltage sags. All the discussed methods for voltage sag source detection have been tested by applying extensive simulations and field tests. The results for ground faults, asymmetrical voltage sags, upstream events and motor starting have been analyzed in order to evaluate all the discussed methods. The obtained results show that all discussed methods are very successful in cases of heavy motor starting and other symmetrical voltage sags. In cases of asymmetrical voltage sags the methods II and III do not work well, especially for those originating from the upstream side, while the method I is not successful only in particular cases of voltage sags due to upstream ground faults. Based on the performed evaluation it can be concluded, that further development is still needed to increase the degree of confidence in the discussed methods.

Practice guidance for the use of terlipressin for liver cirrhosis-related complications (2021)

Liver cirrhosis is a major global health burden worldwide due to its high risk of morbidity and mortality. Role of terlipressin for the management of liver cirrhosis related complications has been recognized during recent years. This paper aims to develop evidence-based clinical practice guidance on the use of terlipressin for liver cirrhosis related complications. Hepatobiliary Study Group of Chinese Society of Gastroenterology of Chinese Medical Association and Hepatology Committee of Chinese Research Hospital Association have invited gastroenterologists, hepatologists, infectious disease specialists, surgeons, and clinical pharmacists to formulate the clinical practice guidance based on comprehensive literature review and experts' clinical experiences. Overall, 10 major statements regarding efficacy and safety of terlipressin in liver cirrhosis were proposed. Terlipressin can be beneficial for the management of cirrhotic patients with acute variceal bleeding and hepatorenal syndrome (HRS). However, the evidence regarding the use of terlipressin in cirrhotic patients with ascites, post-paracentesis circulatory dysfunction, and bacterial infections and in those undergoing hepatic resection and liver transplantation remains insufficient. Terlipressin-related adverse events, mainly including gastrointestinal symptoms, electrolyte disturbance, and cardiovascular and respiratory adverse events, should be closely monitored. The current clinical practice guidance supports the use of terlipressin for gastroesophageal variceal bleeding and HRS in liver cirrhosis. High-quality studies are needed to further clarify its potential effects in other liver cirrhosis related complications.