In this paper,the author follows the trail of C.Malabou,Q.Meillassoux,and G.Deleuze and tries to test three philosophical concepts that seem to be particularly threatened in the era of automatic digital reproduction.T...In this paper,the author follows the trail of C.Malabou,Q.Meillassoux,and G.Deleuze and tries to test three philosophical concepts that seem to be particularly threatened in the era of automatic digital reproduction.These three concepts are plasticity(defended for many years by C.Malabou),contingency(reconstructed by Q.Meillassoux),and virtuality(developed by G.Deleuze).The main task of the text will be to reflect on which of these three concepts better protects our thinking against automation and stays faithful to the ideal of creativity.In what sense are plasticity,contingency,and the possibility of virtualization the a priori condition of any transformation,physical or intellectual,affective or conceptual metamorphosis?In what sense are these three concepts the only conditions for the survival of every living being?Would a being without contingency,plasticity,and disposition to virtualization simply be a dead being?展开更多
Ensuring the reliability of power systems in microgrids is critical,particularly under contingency conditions that can disrupt power flow and system stability.This study investigates the application of Security-Constr...Ensuring the reliability of power systems in microgrids is critical,particularly under contingency conditions that can disrupt power flow and system stability.This study investigates the application of Security-Constrained Optimal Power Flow(SCOPF)using the Line Outage Distribution Factor(LODF)to enhance resilience in a renewable energy-integrated microgrid.The research examines a 30-bus system with 14 generators and an 8669 MW load demand,optimizing both single-objective and multi-objective scenarios.The single-objective opti-mization achieves a total generation cost of$47,738,while the multi-objective approach reduces costs to$47,614 and minimizes battery power output to 165.02 kW.Under contingency conditions,failures in transmission lines 1,22,and 35 lead to complete power loss in those lines,requiring a redistribution strategy.Implementing SCOPF mitigates these disruptions by adjusting power flows,ensuring no line exceeds its capacity.Specifically,in contingency 1,power in channel 4 is reduced from 59 to 32 kW,while overall load shedding is minimized to 0.278 MW.These results demonstrate the effectiveness of SCOPF in maintaining stability and reducing economic losses.Unlike prior studies,this work integrates LODF into SCOPF for large-scale microgrid applications,offering a computationally efficient contingency management framework that enhances grid resilience and supports renewable energy adoption.展开更多
Aimed at the demand of contingency return at any time during the near-moon phase in the manned lunar landing missions,a fast calculation method for three-impulse contingency return trajectories is proposed.Firstly,a t...Aimed at the demand of contingency return at any time during the near-moon phase in the manned lunar landing missions,a fast calculation method for three-impulse contingency return trajectories is proposed.Firstly,a three-impulse contingency return trajectory scheme is presented by combining the Lambert transfer and maneuver at the special point.Secondly,a calculation model of three-impulse contingency return trajectories is established.Then,fast calculation methods are proposed by adopting the high-order Taylor expansion of differential algebra in the twobody trajectory dynamics model and perturbed trajectory dynamics model.Finally,the performance of the proposed methods is verified by numerical simulation.The results indicate that the fast calculation method of two-body trajectory has higher calculation efficiency compared to the semi-analytical calculation method under a certain accuracy condition.Due to its high efficiency,the characteristics of the three-impulse contingency return trajectories under different contingency scenarios are further analyzed expeditiously.These findings can be used for the design of contingency return trajectories in future manned lunar landing missions.展开更多
Objectives:This article aims to summarize a series of contingency management strategies of the Nursing Department in the centralized treatment of patients with coronavirus disease 2019(COVID-19).Methods:The strategies...Objectives:This article aims to summarize a series of contingency management strategies of the Nursing Department in the centralized treatment of patients with coronavirus disease 2019(COVID-19).Methods:The strategies of the Nursing Department included an early warning for prevention and control,taking functions of vertically commanding and horizontally coordinating,and reasonably allocating nursing workforce,to facilitate centralized treatment work in the in-hospital fever clinic,isolation wards and ICU,and referral and admission of critical patients.Five special groups were established in charge of training and examination,management and supervision,psychological support,logistical support,and reporting and publicity,respectively.Results:It was achieved that no deaths from critical patients and no medical staff,no other patients were infected.Conclusion:Through the implementation of these strategies,safe and efficient centralized treatment was ensured timely,orderly and sustainably.展开更多
The purpose of this paper is to propose a new model of asymmetry for square contingency tables with ordered categories. The new model may be appropriate for a square contingency table if it is reasonable to assume an ...The purpose of this paper is to propose a new model of asymmetry for square contingency tables with ordered categories. The new model may be appropriate for a square contingency table if it is reasonable to assume an underlying bivariate t-distribution with different marginal variances having any degrees of freedom. As the degrees of freedom becomes larger, the proposed model approaches the extended linear diagonals-parameter symmetry model, which may be appropriate for a square table if it is reasonable to assume an underlying bivariate normal distribution. The simulation study based on bivariate t-distribution is given. An example is given.展开更多
The electric power infrastructure that has served huge loads for so long is rapidly running up against many limitations. Out of many challenges it is to operate the power system in secure manner so that the operation ...The electric power infrastructure that has served huge loads for so long is rapidly running up against many limitations. Out of many challenges it is to operate the power system in secure manner so that the operation constraints are fulfilled under both normal and contingent conditions. Smart grid technology offers valuable techniques that can be deployed within the very near future or which are already deployed nowadays. Flexible AC Transmission Systems (FACTS) devices have been introduced to solve various power system problems. In literature, most of the methods proposed for sizing the FACTS devices only consider the normal operating conditions of power systems. Consequently, some transmission lines are heavily loaded in contingency case and the system voltage stability becomes a power transfer-limiting factor. This paper presents a technique for determining the proper rating/size of FACTS devices, namely the Static Synchronous Compensator (STATCOM), while considering contingency cases. The paper also verifies that the weakest bus determined by eigenvalue and eigenvectors method is the best location for STATCOM. The rating of STATCOM is specified according to the required reactive power needed to improve voltage stability under normal and contingency cases. Two case system studies are investigated: a simple 5-bus system and the IEEE 14-bus system. The obtained results verify that the rating of STATCOM can be determined according to the worst contingency case, and through proper control it can still be effective for normal and other contingency cases.展开更多
Introduction: Nursing students’ experiences during the pandemic provoked social isolation, the way to learn and every context increasing their stress and anxiety leading to drug use and abuse, among others. Problem-b...Introduction: Nursing students’ experiences during the pandemic provoked social isolation, the way to learn and every context increasing their stress and anxiety leading to drug use and abuse, among others. Problem-based learning (PBL) is a pedagogic strategy to strengthen significant learning;then the objective was to establish PBL influence in nursing students’ experiences on drug use and abuse during COVID-19 contingency. Methods: Qualitative, phenomenological and descriptive paradigm, 12 female and male nursing students aged 20 - 24 years old from the 5<sup>th</sup> and 6<sup>th</sup> semesters participated. Information collection was through semi-structured interview and a deep one in four cases. A guide of questions about: How the pandemic impacted your life? How did you face it? And what did you learn during this process? Those questions were used. Qualitative data analysis was based on De Souza Minayo, and signed informed consent was obtained from participants. Results: Students’ experiences allowed four categories to emerge, with six sub-categories. Category I. Students’ experiences on drug use and abuse facing the sanitary contingency;Category II. Students’ skills development to identify a problem and design of appropriate solutions;Category III. Developing skills to favor interpersonal relationships;Category IV. Influence of PBL in nursing students’ experiences on drug use and abuse during the COVID-19 contingency. Conclusion: PBL favored analysis and thoughts in nursing students’ experiences on drug use and abuse during the COVID-19 contingency, they worked collaboratively, developed resilience to daily life situations, and implemented stress coping strategies with their significant learning, which diminished their risk behavior.展开更多
According to the practice researching and formulating “The Oil Spill Contingency Plan of South Chinese Sea”, this paper analyses and discusses the structure, functions and main contents of marine oil spill contingen...According to the practice researching and formulating “The Oil Spill Contingency Plan of South Chinese Sea”, this paper analyses and discusses the structure, functions and main contents of marine oil spill contingency planning, programs the organizing and commanding system and emergency response system, and advances the planning and researching method to coordinate comprehensively and to design practically the detailed emergency response steps until to formulate the ease operating programs for the plan implementation(PPI) and the PPI to apply high techniques supporting emergency administrations and response.展开更多
In the conventional technique,in the evaluation of the severity index,clustering and loading suffer from more iteration leading to more com-putational delay.Hence this research article identifies,a novel progression f...In the conventional technique,in the evaluation of the severity index,clustering and loading suffer from more iteration leading to more com-putational delay.Hence this research article identifies,a novel progression for fast predicting the severity of the line and clustering by incorporating machine learning aspects.The polynomial load modelling or ZIP(constant impedances(Z),Constant Current(I)and Constant active power(P))is developed in the IEEE-14 and Indian 118 bus systems considered for analysis of power system security.The process of finding the severity of the line using a Hybrid Line Stability Ranking Index(HLSRI)is used for assisting the concepts of machine learning with J48 algorithm,infers the superior affected lines by adopting the IEEE standards in concern to be compensated in maintaining the power system stability.The simulation is performed in the WEKA environment and deals with the supervisor learning in order based on severity to ensure the safety of power system.The Unified Power Flow Controller(UPFC),facts devices for the purpose of compensating the losses by maintaining the voltage characteristics.The finite element analysis findings are compared with the existing procedures and numerical equations for authentications.展开更多
For square contingency tables with ordered categories, this article proposes new models, which are the extension of Tomizawa’s [1] diagonal exponent symmetry model. Also it gives the decomposition of proposed model, ...For square contingency tables with ordered categories, this article proposes new models, which are the extension of Tomizawa’s [1] diagonal exponent symmetry model. Also it gives the decomposition of proposed model, and shows the orthogonality of the test statistics for decomposed models. Examples are given and the simulation studies based on the bivariate normal distribution are also given.展开更多
For square contingency tables with ordered categories, the present paper considers two kinds of weak marginal homogeneity and gives measures to represent the degree of departure from weak marginal homogeneity. The pro...For square contingency tables with ordered categories, the present paper considers two kinds of weak marginal homogeneity and gives measures to represent the degree of departure from weak marginal homogeneity. The proposed measures lie between –1 to 1. When the marginal cumulative logistic model or the extended marginal homogeneity model holds, the proposed measures represent the degree of departure from marginal homogeneity. Using these measures, three kinds of unaided distance vision data are analyzed.展开更多
We present a unified approach to describing and linking several methods for representing categorical data in a contingency table. These methods include: correspondence analysis, Hellinger distance analysis, the log-ra...We present a unified approach to describing and linking several methods for representing categorical data in a contingency table. These methods include: correspondence analysis, Hellinger distance analysis, the log-ratio alternative, which is appropriate for compositional data, and the non-symmetrical correspondence analysis. We also present two solutions working with cummulative frequencies.展开更多
Two test statistics that have been commonly used in analysing interactions in contingency table are the Pearson’s Chi-square statistic, χ2, and likelihood ratio test statistic, G2. Both test statistics, in tables wi...Two test statistics that have been commonly used in analysing interactions in contingency table are the Pearson’s Chi-square statistic, χ2, and likelihood ratio test statistic, G2. Both test statistics, in tables with sufficiently large sample size, have an asymptotic chi-square distribution with degrees of freedom (df) equal to the number of free parameters in the saturated model. For example under the hypothesis of independence of the row and column conditioned on the layer in an I × J × K contingency table, the df is K(I –1)(J– 1). These test statistics, in large sized tables, will have less power since they have large degrees of freedom. This paper proposes a product effect model, which combines the advantages of the multiplicative models over the additive, for analysing the interaction between the row and column of the 3-way table conditioned on the layer. The derived statistics is shown to be asymptotically chi-square with a small degree of freedom, K?– 1, for the I × J × K contingency table. The performance of the developed statistic is compared with the Pearson’s chi-square statistic and the likelihood ratio statistic test using an illustrative example. The results show that the product effect test can detect interaction even when some of the main effects are not significant and can perform better than the other competitors having smaller degree of freedom in large sized tables.展开更多
The aim of this work is to demonstrate that interphase power regulators (I</span></span><span style="white-space:normal;"><span style="font-family:"">PR) bring new...The aim of this work is to demonstrate that interphase power regulators (I</span></span><span style="white-space:normal;"><span style="font-family:"">PR) bring new and interesting ultra-solutions that complement those already taken into account by the FACTS (Flexible Alternative Transmission System) in the resolution of the problems related to the power flow in the AC transmission networks. In order to facilitate the understanding of this work, a comparative study of the performances of the two technologies between the UPFC (Unified Power Flow Controller) and RPI was carried out and at the end of which we were able to highlight the preponderance of RPI compared to the UPFC in the bypassing of the short-circuit fault insofar as the latter allows, in particular, an increase in the transformation capacity without an increase in the level of the short-circuit. The decoupled watt-var method has been used to control the UPFC while the RPI is controlled by phase shift. The simulation results are obtained in the Matlab Simulink environment and show the flexibility of the RPI compared to the UPFC in limiting strong contingencies.展开更多
Southern Africa has experienced electric power deficits over the last decade. This has been due in part to the member countries＇ inadequate electrical power supply system, as well as load growth in areas which were n...Southern Africa has experienced electric power deficits over the last decade. This has been due in part to the member countries＇ inadequate electrical power supply system, as well as load growth in areas which were not adequately planned for. This has induced the formation of organizations such as SADC （Southern African Development Community） and SAPP （Southern African Power Pool） that have the common goal of achieving development and economic growth in the region which comprises of 15 member countries. This paper presents results from a security analysis of the region＇s electric power supply system using a baseline level of performance. This was carried out by performing a steady-state contingency analysis on a SADC power network model subject to the N-1 criteria which expresses the ability of the power network to experience a contingency without causing an overload or failure in any other part of the network. Simulations were carried out using DigSilent.展开更多
This research focuses on restructuring medium-level voltage(MLV)distribution systems by integrating distributed renewable energy resources(DER)at multiple feed points.It examines the impact of incorporating renewable ...This research focuses on restructuring medium-level voltage(MLV)distribution systems by integrating distributed renewable energy resources(DER)at multiple feed points.It examines the impact of incorporating renewable energy and evaluates system performance metrics such as robustness,static voltage stability,line carrying capacity,utility grid effectiveness,and losses within the conventional radial distribution framework commonly used in educational institutions.The contingency ranking of the real-time radial distribution system(RTRDS)for a typical educational institution consisting of N buses was conducted.Parameters such as the Voltage Performance Index(PIV)and Flow Performance Index(PIF)were evaluated.The results support the integration of distributed renewable energy sources within the existing radial distribution grid infrastructure.This research proposes enhanced contingency analyses through a straightforward reconfiguration process involving an additional tie line(Nþ1)for the existing N bus radial distribution system(RDS).Load flow analysis of the RDS with distributed renewable energy resources(DER)for both N bus and Nþ1 bus systems was conducted using the Gauss-Seidel and Newton–Raphson methods.Simulation results indicate that baseline loading is consistently maintained by grid sources and DER sources connected at multiple feed points.The proposed configuration of the Nþ1 bus system for the existing RTRDS was evaluated for voltage performance and compared with the Grey Wolf Optimization(GWO)algorithm.The results indicate that the Nþ1 bus configuration modeled using the MiPower tool performed comparably to the GWO results.Additionally,the contingency ranking for the proposed Nþ1 configuration was validated using the IEEE 10 and 30 bus system.展开更多
N−1 security is an important criterion for the development and planning of distribution networks.The existing N−1 contingency analysis methods of distribution networks are primarily based on the unit of components,and...N−1 security is an important criterion for the development and planning of distribution networks.The existing N−1 contingency analysis methods of distribution networks are primarily based on the unit of components,and the faults of each component are analyzed and verified one by one.The calculation process of these methods is complicated,and the positioning effect of the weak links needed for distribution network planning is insufficient.For this reason,this paper proposes a method of N−1 contingency parallel analysis for main transformers based on the incidence matrix.First,the main transformer incidence matrix is established,and the load transfer process is classified into three types,according to different transfer modes,and the contact matrices are then established respectively.Second,considering the capacity constraint of main transformers and tie-lines,the corresponding capacity matrices are established.The maximum transfer capability(MTC)of the distribution network in the case of each main transformer fault is calculated by contact matrices and capacity matrices,and the N−1 contingency analysis result is obtained by comparing MTC with the load that needs transferring.Meanwhile,the transfer margin of the main transformers and tie-lines after transferring can be obtained in the process of N−1 contingency analysis,so as to find any weak links.An example is given to verify the correctness and effectiveness of the proposed method.In this paper,the N−1 contingency analysis results of all main transformers in the distribution network are expressed analytically through matrices operations,and the weak links can then be intuitively identified.The cumbersome operation of checking each component is avoided,and the computational efficiency is improved.展开更多
The use of unmanned aerial system(UAS)in congested airspace and/or in the proximity of critical infrastructure poses several challenges as far as safe and secure operations are concerned.The paper provides a detailed ...The use of unmanned aerial system(UAS)in congested airspace and/or in the proximity of critical infrastructure poses several challenges as far as safe and secure operations are concerned.The paper provides a detailed description of the architecture and workflow of a platform for UAS traffic management(UTM),designed to pave the way for increased,improved and safer UAS operations in the civil airspace.In particular,access to low-altitude airspace for UAS operations is managed,while facilitating the implementation of beyond visual line-of-sight(BVLOS)operations,and ensuring a safe and efficient integration of UAS into both controlled and uncontrolled airspace.Detection and management of unidentified or uncooperative UAS’s is also taken care of.To this end,an architecture based on three interacting layers is proposed,with the air traffic control at the highest level,the UAS operator(s)at the bottom,and a UAS service supplier acting as an interface.The platform,with its physical and digital elements,guarantees the effective and efficient interaction among these three layers,including management of contingency scenarios,which require a variation of admissible flight volumes for UAS operations and/or fast trajectory re-planning.The platform,developed within a research project which involved several partners,was tested in a relevant operational scenario at the Grottaglie-Taranto airport in Italy.The operators involved in the tests provided positive feedback on the services provided by the platform and the usability of the interfaces,while also making suggestions for adding new features in future developments.展开更多
In this paper,a novel contingency-aware method for N-2 security-constrained transmission expansion planning is proposed.To ensure that the transmission construction plan satisfies the N-2 security criterion,the propos...In this paper,a novel contingency-aware method for N-2 security-constrained transmission expansion planning is proposed.To ensure that the transmission construction plan satisfies the N-2 security criterion,the proposed method takes advantage of the adjustable robust optimization(ARO)framework and upgrades it.We construct a discrete uncertainty set in which component failures are treated as uncertain events that are handled as binary variables.In addition to the failure of existing lines and generators,we explicitly model the failure of candidate lines.The proposed model comprises a master problem that makes the transmission construction decision,and a series of subproblems that can detect not only the worst contingency,but also the potential contingencies.Computational studies on the IEEE RTS 24-bus and IEEE 118-bus test systems are carried out to validate the effectiveness of the proposed method.Compared with the deterministic method and ARO method in the literature,the proposed method has higher computational efficiency.展开更多
文摘In this paper,the author follows the trail of C.Malabou,Q.Meillassoux,and G.Deleuze and tries to test three philosophical concepts that seem to be particularly threatened in the era of automatic digital reproduction.These three concepts are plasticity(defended for many years by C.Malabou),contingency(reconstructed by Q.Meillassoux),and virtuality(developed by G.Deleuze).The main task of the text will be to reflect on which of these three concepts better protects our thinking against automation and stays faithful to the ideal of creativity.In what sense are plasticity,contingency,and the possibility of virtualization the a priori condition of any transformation,physical or intellectual,affective or conceptual metamorphosis?In what sense are these three concepts the only conditions for the survival of every living being?Would a being without contingency,plasticity,and disposition to virtualization simply be a dead being?
文摘Ensuring the reliability of power systems in microgrids is critical,particularly under contingency conditions that can disrupt power flow and system stability.This study investigates the application of Security-Constrained Optimal Power Flow(SCOPF)using the Line Outage Distribution Factor(LODF)to enhance resilience in a renewable energy-integrated microgrid.The research examines a 30-bus system with 14 generators and an 8669 MW load demand,optimizing both single-objective and multi-objective scenarios.The single-objective opti-mization achieves a total generation cost of$47,738,while the multi-objective approach reduces costs to$47,614 and minimizes battery power output to 165.02 kW.Under contingency conditions,failures in transmission lines 1,22,and 35 lead to complete power loss in those lines,requiring a redistribution strategy.Implementing SCOPF mitigates these disruptions by adjusting power flows,ensuring no line exceeds its capacity.Specifically,in contingency 1,power in channel 4 is reduced from 59 to 32 kW,while overall load shedding is minimized to 0.278 MW.These results demonstrate the effectiveness of SCOPF in maintaining stability and reducing economic losses.Unlike prior studies,this work integrates LODF into SCOPF for large-scale microgrid applications,offering a computationally efficient contingency management framework that enhances grid resilience and supports renewable energy adoption.
基金co-supported by the National Natural Science Foundation of China(No.12072365)the Technology Innovation Team of Manned Space Engineering,China。
文摘Aimed at the demand of contingency return at any time during the near-moon phase in the manned lunar landing missions,a fast calculation method for three-impulse contingency return trajectories is proposed.Firstly,a three-impulse contingency return trajectory scheme is presented by combining the Lambert transfer and maneuver at the special point.Secondly,a calculation model of three-impulse contingency return trajectories is established.Then,fast calculation methods are proposed by adopting the high-order Taylor expansion of differential algebra in the twobody trajectory dynamics model and perturbed trajectory dynamics model.Finally,the performance of the proposed methods is verified by numerical simulation.The results indicate that the fast calculation method of two-body trajectory has higher calculation efficiency compared to the semi-analytical calculation method under a certain accuracy condition.Due to its high efficiency,the characteristics of the three-impulse contingency return trajectories under different contingency scenarios are further analyzed expeditiously.These findings can be used for the design of contingency return trajectories in future manned lunar landing missions.
基金Zhejiang Medical Science and Technology Plan Project(2019RC167).
文摘Objectives:This article aims to summarize a series of contingency management strategies of the Nursing Department in the centralized treatment of patients with coronavirus disease 2019(COVID-19).Methods:The strategies of the Nursing Department included an early warning for prevention and control,taking functions of vertically commanding and horizontally coordinating,and reasonably allocating nursing workforce,to facilitate centralized treatment work in the in-hospital fever clinic,isolation wards and ICU,and referral and admission of critical patients.Five special groups were established in charge of training and examination,management and supervision,psychological support,logistical support,and reporting and publicity,respectively.Results:It was achieved that no deaths from critical patients and no medical staff,no other patients were infected.Conclusion:Through the implementation of these strategies,safe and efficient centralized treatment was ensured timely,orderly and sustainably.
文摘The purpose of this paper is to propose a new model of asymmetry for square contingency tables with ordered categories. The new model may be appropriate for a square contingency table if it is reasonable to assume an underlying bivariate t-distribution with different marginal variances having any degrees of freedom. As the degrees of freedom becomes larger, the proposed model approaches the extended linear diagonals-parameter symmetry model, which may be appropriate for a square table if it is reasonable to assume an underlying bivariate normal distribution. The simulation study based on bivariate t-distribution is given. An example is given.
文摘The electric power infrastructure that has served huge loads for so long is rapidly running up against many limitations. Out of many challenges it is to operate the power system in secure manner so that the operation constraints are fulfilled under both normal and contingent conditions. Smart grid technology offers valuable techniques that can be deployed within the very near future or which are already deployed nowadays. Flexible AC Transmission Systems (FACTS) devices have been introduced to solve various power system problems. In literature, most of the methods proposed for sizing the FACTS devices only consider the normal operating conditions of power systems. Consequently, some transmission lines are heavily loaded in contingency case and the system voltage stability becomes a power transfer-limiting factor. This paper presents a technique for determining the proper rating/size of FACTS devices, namely the Static Synchronous Compensator (STATCOM), while considering contingency cases. The paper also verifies that the weakest bus determined by eigenvalue and eigenvectors method is the best location for STATCOM. The rating of STATCOM is specified according to the required reactive power needed to improve voltage stability under normal and contingency cases. Two case system studies are investigated: a simple 5-bus system and the IEEE 14-bus system. The obtained results verify that the rating of STATCOM can be determined according to the worst contingency case, and through proper control it can still be effective for normal and other contingency cases.
文摘Introduction: Nursing students’ experiences during the pandemic provoked social isolation, the way to learn and every context increasing their stress and anxiety leading to drug use and abuse, among others. Problem-based learning (PBL) is a pedagogic strategy to strengthen significant learning;then the objective was to establish PBL influence in nursing students’ experiences on drug use and abuse during COVID-19 contingency. Methods: Qualitative, phenomenological and descriptive paradigm, 12 female and male nursing students aged 20 - 24 years old from the 5<sup>th</sup> and 6<sup>th</sup> semesters participated. Information collection was through semi-structured interview and a deep one in four cases. A guide of questions about: How the pandemic impacted your life? How did you face it? And what did you learn during this process? Those questions were used. Qualitative data analysis was based on De Souza Minayo, and signed informed consent was obtained from participants. Results: Students’ experiences allowed four categories to emerge, with six sub-categories. Category I. Students’ experiences on drug use and abuse facing the sanitary contingency;Category II. Students’ skills development to identify a problem and design of appropriate solutions;Category III. Developing skills to favor interpersonal relationships;Category IV. Influence of PBL in nursing students’ experiences on drug use and abuse during the COVID-19 contingency. Conclusion: PBL favored analysis and thoughts in nursing students’ experiences on drug use and abuse during the COVID-19 contingency, they worked collaboratively, developed resilience to daily life situations, and implemented stress coping strategies with their significant learning, which diminished their risk behavior.
文摘According to the practice researching and formulating “The Oil Spill Contingency Plan of South Chinese Sea”, this paper analyses and discusses the structure, functions and main contents of marine oil spill contingency planning, programs the organizing and commanding system and emergency response system, and advances the planning and researching method to coordinate comprehensively and to design practically the detailed emergency response steps until to formulate the ease operating programs for the plan implementation(PPI) and the PPI to apply high techniques supporting emergency administrations and response.
文摘In the conventional technique,in the evaluation of the severity index,clustering and loading suffer from more iteration leading to more com-putational delay.Hence this research article identifies,a novel progression for fast predicting the severity of the line and clustering by incorporating machine learning aspects.The polynomial load modelling or ZIP(constant impedances(Z),Constant Current(I)and Constant active power(P))is developed in the IEEE-14 and Indian 118 bus systems considered for analysis of power system security.The process of finding the severity of the line using a Hybrid Line Stability Ranking Index(HLSRI)is used for assisting the concepts of machine learning with J48 algorithm,infers the superior affected lines by adopting the IEEE standards in concern to be compensated in maintaining the power system stability.The simulation is performed in the WEKA environment and deals with the supervisor learning in order based on severity to ensure the safety of power system.The Unified Power Flow Controller(UPFC),facts devices for the purpose of compensating the losses by maintaining the voltage characteristics.The finite element analysis findings are compared with the existing procedures and numerical equations for authentications.
文摘For square contingency tables with ordered categories, this article proposes new models, which are the extension of Tomizawa’s [1] diagonal exponent symmetry model. Also it gives the decomposition of proposed model, and shows the orthogonality of the test statistics for decomposed models. Examples are given and the simulation studies based on the bivariate normal distribution are also given.
文摘For square contingency tables with ordered categories, the present paper considers two kinds of weak marginal homogeneity and gives measures to represent the degree of departure from weak marginal homogeneity. The proposed measures lie between –1 to 1. When the marginal cumulative logistic model or the extended marginal homogeneity model holds, the proposed measures represent the degree of departure from marginal homogeneity. Using these measures, three kinds of unaided distance vision data are analyzed.
文摘We present a unified approach to describing and linking several methods for representing categorical data in a contingency table. These methods include: correspondence analysis, Hellinger distance analysis, the log-ratio alternative, which is appropriate for compositional data, and the non-symmetrical correspondence analysis. We also present two solutions working with cummulative frequencies.
文摘Two test statistics that have been commonly used in analysing interactions in contingency table are the Pearson’s Chi-square statistic, χ2, and likelihood ratio test statistic, G2. Both test statistics, in tables with sufficiently large sample size, have an asymptotic chi-square distribution with degrees of freedom (df) equal to the number of free parameters in the saturated model. For example under the hypothesis of independence of the row and column conditioned on the layer in an I × J × K contingency table, the df is K(I –1)(J– 1). These test statistics, in large sized tables, will have less power since they have large degrees of freedom. This paper proposes a product effect model, which combines the advantages of the multiplicative models over the additive, for analysing the interaction between the row and column of the 3-way table conditioned on the layer. The derived statistics is shown to be asymptotically chi-square with a small degree of freedom, K?– 1, for the I × J × K contingency table. The performance of the developed statistic is compared with the Pearson’s chi-square statistic and the likelihood ratio statistic test using an illustrative example. The results show that the product effect test can detect interaction even when some of the main effects are not significant and can perform better than the other competitors having smaller degree of freedom in large sized tables.
文摘The aim of this work is to demonstrate that interphase power regulators (I</span></span><span style="white-space:normal;"><span style="font-family:"">PR) bring new and interesting ultra-solutions that complement those already taken into account by the FACTS (Flexible Alternative Transmission System) in the resolution of the problems related to the power flow in the AC transmission networks. In order to facilitate the understanding of this work, a comparative study of the performances of the two technologies between the UPFC (Unified Power Flow Controller) and RPI was carried out and at the end of which we were able to highlight the preponderance of RPI compared to the UPFC in the bypassing of the short-circuit fault insofar as the latter allows, in particular, an increase in the transformation capacity without an increase in the level of the short-circuit. The decoupled watt-var method has been used to control the UPFC while the RPI is controlled by phase shift. The simulation results are obtained in the Matlab Simulink environment and show the flexibility of the RPI compared to the UPFC in limiting strong contingencies.
文摘Southern Africa has experienced electric power deficits over the last decade. This has been due in part to the member countries＇ inadequate electrical power supply system, as well as load growth in areas which were not adequately planned for. This has induced the formation of organizations such as SADC （Southern African Development Community） and SAPP （Southern African Power Pool） that have the common goal of achieving development and economic growth in the region which comprises of 15 member countries. This paper presents results from a security analysis of the region＇s electric power supply system using a baseline level of performance. This was carried out by performing a steady-state contingency analysis on a SADC power network model subject to the N-1 criteria which expresses the ability of the power network to experience a contingency without causing an overload or failure in any other part of the network. Simulations were carried out using DigSilent.
文摘This research focuses on restructuring medium-level voltage(MLV)distribution systems by integrating distributed renewable energy resources(DER)at multiple feed points.It examines the impact of incorporating renewable energy and evaluates system performance metrics such as robustness,static voltage stability,line carrying capacity,utility grid effectiveness,and losses within the conventional radial distribution framework commonly used in educational institutions.The contingency ranking of the real-time radial distribution system(RTRDS)for a typical educational institution consisting of N buses was conducted.Parameters such as the Voltage Performance Index(PIV)and Flow Performance Index(PIF)were evaluated.The results support the integration of distributed renewable energy sources within the existing radial distribution grid infrastructure.This research proposes enhanced contingency analyses through a straightforward reconfiguration process involving an additional tie line(Nþ1)for the existing N bus radial distribution system(RDS).Load flow analysis of the RDS with distributed renewable energy resources(DER)for both N bus and Nþ1 bus systems was conducted using the Gauss-Seidel and Newton–Raphson methods.Simulation results indicate that baseline loading is consistently maintained by grid sources and DER sources connected at multiple feed points.The proposed configuration of the Nþ1 bus system for the existing RTRDS was evaluated for voltage performance and compared with the Grey Wolf Optimization(GWO)algorithm.The results indicate that the Nþ1 bus configuration modeled using the MiPower tool performed comparably to the GWO results.Additionally,the contingency ranking for the proposed Nþ1 configuration was validated using the IEEE 10 and 30 bus system.
基金supported in part by National Key Research and Development Program of China under Grant 2020YFB0906000in part by National Natural Science Foundation of China under Grant 51977140,Grant U1866207 and Grant 51207101in part by Natural Science Foundation of Tianjin under Grant 19JCYBJC21300。
文摘N−1 security is an important criterion for the development and planning of distribution networks.The existing N−1 contingency analysis methods of distribution networks are primarily based on the unit of components,and the faults of each component are analyzed and verified one by one.The calculation process of these methods is complicated,and the positioning effect of the weak links needed for distribution network planning is insufficient.For this reason,this paper proposes a method of N−1 contingency parallel analysis for main transformers based on the incidence matrix.First,the main transformer incidence matrix is established,and the load transfer process is classified into three types,according to different transfer modes,and the contact matrices are then established respectively.Second,considering the capacity constraint of main transformers and tie-lines,the corresponding capacity matrices are established.The maximum transfer capability(MTC)of the distribution network in the case of each main transformer fault is calculated by contact matrices and capacity matrices,and the N−1 contingency analysis result is obtained by comparing MTC with the load that needs transferring.Meanwhile,the transfer margin of the main transformers and tie-lines after transferring can be obtained in the process of N−1 contingency analysis,so as to find any weak links.An example is given to verify the correctness and effectiveness of the proposed method.In this paper,the N−1 contingency analysis results of all main transformers in the distribution network are expressed analytically through matrices operations,and the weak links can then be intuitively identified.The cumbersome operation of checking each component is avoided,and the computational efficiency is improved.
基金supported by the European Union and Italian Ministry of University and Research through the call PON Research and Innovation 2014-2020,Axis Ⅱ,Action 2,project AcrOSS(Environment for Safe Operations of Remotely Piloted Aircraft),project number ARS01_00702-CUP:F36C18000210005.
文摘The use of unmanned aerial system(UAS)in congested airspace and/or in the proximity of critical infrastructure poses several challenges as far as safe and secure operations are concerned.The paper provides a detailed description of the architecture and workflow of a platform for UAS traffic management(UTM),designed to pave the way for increased,improved and safer UAS operations in the civil airspace.In particular,access to low-altitude airspace for UAS operations is managed,while facilitating the implementation of beyond visual line-of-sight(BVLOS)operations,and ensuring a safe and efficient integration of UAS into both controlled and uncontrolled airspace.Detection and management of unidentified or uncooperative UAS’s is also taken care of.To this end,an architecture based on three interacting layers is proposed,with the air traffic control at the highest level,the UAS operator(s)at the bottom,and a UAS service supplier acting as an interface.The platform,with its physical and digital elements,guarantees the effective and efficient interaction among these three layers,including management of contingency scenarios,which require a variation of admissible flight volumes for UAS operations and/or fast trajectory re-planning.The platform,developed within a research project which involved several partners,was tested in a relevant operational scenario at the Grottaglie-Taranto airport in Italy.The operators involved in the tests provided positive feedback on the services provided by the platform and the usability of the interfaces,while also making suggestions for adding new features in future developments.
基金supported by the National Key Research and Development Plan of China(No.2016YFB0900100)National Natural Science Foundation of China(No.51807116).
文摘In this paper,a novel contingency-aware method for N-2 security-constrained transmission expansion planning is proposed.To ensure that the transmission construction plan satisfies the N-2 security criterion,the proposed method takes advantage of the adjustable robust optimization(ARO)framework and upgrades it.We construct a discrete uncertainty set in which component failures are treated as uncertain events that are handled as binary variables.In addition to the failure of existing lines and generators,we explicitly model the failure of candidate lines.The proposed model comprises a master problem that makes the transmission construction decision,and a series of subproblems that can detect not only the worst contingency,but also the potential contingencies.Computational studies on the IEEE RTS 24-bus and IEEE 118-bus test systems are carried out to validate the effectiveness of the proposed method.Compared with the deterministic method and ARO method in the literature,the proposed method has higher computational efficiency.
