Response Of Protection System Research Articles

Ablation simulation of integral woven gradient three‐dimensional thermal protection structures for planetary exploration

AbstractFor the harsh entry environment and higher thermal protection requirements, two structures of three‐dimensional woven gradient thermal protection materials were designed and prepared with the deep space exploration thermal protection system as the object. They are 3D orthogonal woven, 2.5D layer‐to‐layer angle interlock woven, 2.5D layer‐layer angle interlock woven structure(OLL) composite and 3D orthogonal woven, angle 2.5D layer‐to‐layer angle interlock woven, honeycomb structure(OLH) composite. Two materials were prepared and examined by ablation in an oxygen‐acetylene flame. A three‐dimensional macroscopic ablation model was established on the basis of the experiment, and the model was verified to be accurate and effective, which can well respond to the pyrolytic ablation process of the materials. The two designed materials are applied to the outsole of MSL by simulation, and the three‐dimensional response during the entry into Mars is simulated and analyzed in comparison with the thermal protection performance of PICA material. Both materials show better thermal protection than PICA and can be used as a reference in the selection of thermal protection materials.Highlights Two kinds of 3D gradient woven thermal protection materials are designed. A 3D thermal protection system response model is established. The three‐dimensional response during entry was analyzed. Thermal protection of the material is superior to that of PICA.

Child Protection System Interactions for Children With Positive Urine Screens for Illicit Drugs

Young children are ingesting illicit drugs at increased rates, but it is unknown what the associated child protection system (CPS) responses are when a child tests positive. To document the child protection system involvement and the characteristics of children who test positive for illicit substances. This retrospective cross-sectional study linked medical discharge and child protection system administrative data. The setting was Rady Children's Hospital San Diego, a free-standing pediatric hospital in California. Participants included all emergency department and inpatient medical encounters involving children aged 12 years or younger with a positive urine drug test between 2016 and 2021. Statistical analysis was performed from February 2023 to January 2024. Drug type, including amphetamines, barbiturates, benzodiazepines, cannabis, cocaine, fentanyl, opiates, and phencyclidine. CPS responses associated with the medical encounter including reports, substantiations, case openings, and out-of-home placements. A total of 511 emergency department and inpatient medical encounters involving children had a positive drug test (262 [51.3%] were female; 309 [60.5%] were age 6 years or younger; fewer than 10 [<3.0%] were American Indian or Alaska Native; 252 [49.3%] were Hispanic [any race], 20 [3.9%] were non-Hispanic Asian, 56 [11.0%] were non-Hispanic Black, 143 [28.0%] were non-Hispanic White, 36 [7.0%] had other or unknown race and ethnicity; 233 [43.6%] had a CPS report prior to the medical encounter). Following the positive screen, 244 (47.7%) were reported to child protection, and 61 (11.9%) were placed out-of-home within 30 days. Mean (SD) quarterly counts of encounters with positive drug tests doubled after the COVID-19 pandemic onset (32.9 [9.8]) compared with prior to the pandemic onset (16.5 [4.7]); for encounters positive for cannabis, mean (SD) quarterly counts were 3 times as high after the pandemic onset than prior (16.6 [4.7] vs 5.7 [2.9]). Encounters for children under age 1 were significantly more likely to have associated child protection reports (relative risk [RR], 2.91 [95% CI, 2.21-3.83]) and child protection case openings (RR, 1.71 [95% CI, 1.07-2.72]) than encounters involving older children. In this cross-sectional study of emergency department and inpatient medical encounters, less than half of children with positive urine drug screens were reported to CPS; out-of-home placements were uncommon. With increased encounters for positive drug tests, it is unclear what services these children and families are receiving.

Supervisory neglect: Critical questions regarding child supervision and protection system responses

Concerns about child supervision are present in a large proportion of the circumstances responded to by North American child protection systems. This paper examines different perspectives on low-supervision, from parental-deficit to critical-ecological formulations, to address two questions that are central to assessing reports: why low-supervision is deemed to be harmful, and why low-supervision events occur The implications of this knowledge for child protection system responses is explored, and the conceptualization and application of supervisory neglect as a maltreatment category is critically questioned in order to tease apart what this label may represent in practice. The paper considers how thinking could be reframed to make supervisory neglect a more discrete classification which informs subsequent action, including centering the environmental hazard in supervisory neglect formulations and giving primacy to the impact on the child rather than to parent behavior. The role of normative thinking in decision-making and the risk of perpetuating social inequalities and oppressive power is also considered. More research is required to examine responses and outcomes under current systems of practice, and how child protection workers and systems reflexively analyze reports. In addition, more societal dialogue is needed to prevent widespread risk-averse thinking about how children should be supervised, which can reinforce restrictive child protection policy.

The Implementation of the Low Voltage Ride-Through Curve on the Protection System of a Wind Power Plant

. This paper presents the implementation of the low voltage ride-through (LVRT) curve in two commercial numerical relays, assessing the features and limitations of each protection device. The LVRT curve is defined in grid codes of several countries, especially those who already have or are planning a high share of wind power in their electric power systems. The functionality of the wind turbine grid protection system is tested in a power system using the PSCAD/EMTDC simulation tool. The fault ride through capability curve applied in the test system is as defined in the Brazilian grid code and the protection system responses evaluated at the point of common coupling of the wind power plant when the power network is under symmetrical and unsymmetrical faults. The biggest challenge to adhere the system operator requirements is to ensure the highest conformity to the defined LVRT curve, because most relays only gives you the option of tuning in discrete time intervals.

Design Method and Impact Response of Energy-Consuming High-Fall Flexible Protection System for Construction

High-fall accidents refer to accidents where construction personnel, building materials, and equipment fall from a height, usually resulting in serious casualties and significant economic losses. This paper proposes a high-fall flexible protection system and its design approach with a tensile yield energy-consuming mechanism to solve high-fall accidents. The design approach based on component characteristics that obtained through tests contains energy matching, component internal force balance, and a two-level energy consumption mechanism. Component tests were conducted with mesh bursting tests and energy dissipator static tensile tests to obtain the characteristics of the intercepting net under the flexible boundary condition, and the force-displacement model of the ring-type energy dissipater. Combined with an actual project, we designed a high-fall flexible protection system with a protection energy level of 800 kJ for the core tube of an ultra-high-rise building construction using this method. The impact of dynamic response under multiple cases including the overall fall of the construction formwork was analyzed by dynamical numerical calculation models. The result shows that the system can effectively intercept high-falling objects and exhibit good two-stage energy dissipation characteristics to consume the impact energy. Compared with the protection system without an energy consumption mechanism, the internal force response of the steel wire rope and the suspended frame reduce by about 60%, and the energy consumption capacity increase more than six times. The protection technique proposed in this paper can effectively solve the problem of high-level impact protection such as falling construction formwork equipment, and improve construction safety.

Novel Engineering Methodology for Decoupled Aerothermal Analysis of Hypersonic Atmospheric Entry Flows

Analyses of thermal protection system response to atmospheric entry are generally performed in a decoupled manner where some terms in the surface balance equations are simplified. In such an approach, surface fluxes are calculated using a fluid dynamics solution of the hypersonic flowfield. These are nondimensionalized for use by a material response code, where correction terms are applied to account for the missing physics. A new method is presented here that directly includes ablation physics, thus removing the need for correction models. This approach includes the diffusion processes of ablative species in the boundary layer and nonequilibrium surface chemistry. The new approach is compared to the heritage methodology using a trajectory designed to allow molecular dissociation and vibrational energy contribution. The new methodology predicts surface temperatures with the same qualitative trend, with the largest disagreements in areas of the trajectory where nonequilibrium effects are expected to occur. The solid ablation flux and subsequent recession behavior are consistently lower for the new method, but this discrepancy in surface thermochemistry can be decreased by adopting kinetic models with more aggressive oxidation mechanisms. It is found that a large difference in computed recession does not necessarily equate to the largest difference in heat shield sizing.

Intelligent Relay Protection System for Overhead Lines in Electrical Networks with Low Earth Fault Currents

Nuclear power plants (NPP) are one of the main sources of electricity. The distribution of electricity generated by nuclear power plants, or backup power supply to individual consumers of the power plant's own needs, can be carried out via a 6-35 kV network. These networks operate with an isolated or compensated neutral. This causes the fact that the currents of single-phase ground faults (SPGF) in case of accidents on overhead power lines (OL) are quite small and SPGF are difficult to identify. The article deals with the issues of identifying the SPGF and the corresponding selective response of the overhead line protection system. The limitation of the functioning of relay protection against SPGF, built on the classical principle of operation "if-then", is proved. The error of the traditional protection system is explained by the lack of a mechanism for updating the setpoints in accordance with changes in environmental conditions that affect the capacitive component of the conductivity of overhead lines. As an example of similar an influence, the effect of icing of wires, as well as the triboelectric effect in the form of accumulation of a space charge in the air gap around the line, is described. In this regard, a method is described for correcting the protection setpoints due to periodic measurements of the capacitance of the lines by means of their location probing. Thus, it is proposed to improve the traditional current protection against SPGF by giving the system the ability to adapt, but within the framework of its response as an agent with a simple behavior. The construction of a more advanced system of protection against SPGF in the form of an intelligent agent of the electrical network is also considered. The essence of this system is to use an artificial neural network as a subagent processing information. The advantage of a neurocomputer system for protection against SPGF is proved, which forms an integral assessment of the state of power transmission lines and learns to detect SPGF on a digital shadow following the electrical network. It indicates the possibility of classifying the proposed system of protection against SPGF as an intelligent agent due to the ability to adapt, learn and develop.

The Impact of the COVID-19 Pandemic on Child Protection System Referrals and Responses in Colorado, USA.

Although the coronavirus disease 2019 (COVID-19) has amplified risk factors known to increase children's vulnerability to abuse and neglect, emerging evidence suggests declines in maltreatment reporting and responding following COVID-19 social distancing protocols in the United States. Using statewide administrative data, this study builds on the current state of knowledge to better understand the volume of child protection system (CPS) referrals and responses in Colorado, USA before and during the early phase of the COVID-19 pandemic and to determine whether there were differences in referral and response rates by case characteristics. Results indicated an overall decline in referrals and responses during COVID-19 when compared to the previous year. Declines were specific to case characteristics, such as reporter and maltreatment type. Implications regarding the impact of the COVID-19 pandemic on child maltreatment reporting and CPS response are discussed.

Heat transfer with interface effects in high-enthalpy and high-speed flow: Modelling review and recent progress

Aerodynamics, aerothermodynamics and thermal protection system response in high-enthalpy and high-speed flow is heat transfer with interface effects in nature. Modelling and simulation of these phenomena are of vital significance to ensure high-speed flight thermal safety. The heat transfer phenomena related with gas-surface interaction, interface heterogeneous reactions and microstructure morphology in high-enthalpy and high-speed flow were summarized. The modelling of interface effects and the corresponding coupling algorithms for computational fluid dynamics (CFD) and related approaches were reviewed. Recent research activities for interface problems in high-enthalpy and high-speed flow at China Aerodynamics Research and Development Center were discussed. They mainly focus on practical solutions of computational fluid dynamics with viscous wall boundary conditions, multi-zone coupling for fluid-thermal interaction and cross-scale algorithms of CFD coupled with smaller scale theoretical approaches. Finally, further perspectives about heat transfer with interface effects were proposed, including mesoscale experimental verification, interface cross-scale modelling and accuracy/uncertainty of coupling algorithms.

The Role of Para Social Workers in Rural Communities in Uganda: Strengthening Community Resilience for the Protection of Children

Para social workers (PSWs) are widely used in African nations to address inadequate capacity in the professional workforce, but there is to date very little academic commentary on the effectiveness of their role. This article considers the potential efficacy of the PSW model in strengthening child protection at community level in Uganda. Twenty interviews were conducted with local government officers, civil society organisation staff and PSWs (10 in each of 2 rural areas), together with four supplementary expert interviews. The data were analysed using a framework of community resilience. The findings suggest that the model has considerable potential to strengthen community‐level protection of children in circumstances in which the operation of formal systems is limited by resource constraints and outside interventions may struggle to gain understanding and acceptance within communities. Challenges include the potential for conflicts of interest to arise and the implications of increased reporting of child maltreatment for the response of the formal child protection system, including alternative care arrangements. Given its widespread and developing usage, further research to understand the conditions under which the PSW model is most effective and sustainable in different social, economic, political and cultural contexts is essential.‘This article considers the potential efficacy of the PSW [para social worker] model in strengthening child protection at community level in Uganda’Key Practitioner Messages PSWs can provide significant additional capacity to community‐level child protection arrangements at little cost in a culturally appropriate fashion. A key strength of the PSW model lies in its potential to regenerate community resources through the engagement of community members. Developing sustainable community‐based child protection arrangements requires that attention is paid to balancing fiscal considerations against community ownership and also the response of the formal child protection system to increased reporting of child maltreatment.

Research of the corporate network information protection system based on GNS3

A study of the information protection system of a corporate network based on GNS3 was performed. A simulation model of the corporate network protection system based on GNS3 has been built. The GNS3 program is a graphical network emulator that allows you to simulate a virtual network that consists of network equipment of more than twenty different manufacturers on a local computer, and connect a virtual network to a real network. The corporate network information protection system consists of Gateway, Firewall, Digital Signature Verifier and Logger microservices. We used elements that will allow us to test the protection system as a complete simulation model. A software package was developed using ASP.NET Core technology. The application architecture is implemented using the design pattern of "microservice architecture". Each element of the protection system, its role, functions and implementation are considered. SQL Injection and Cross-site scripting threat protection was implemented. Digital signature verification provides an additional layer of information security. The response of the corporate network information protection system to a threatened request is presented. Logging was analyzed using the Logger microservice, protection analysis will further identify weak points of protection and develop improvements. Conducted stress tests using the Vega program (to fulfill the goals of the attacker, the Kali Linux software operating system was chosen) showed that the system is very resistant to attacks such as SQL Injection and Cross-site scripting. A simulation model of the corporate network protection system based on GNS3 using a digital signature of a minimum size with a specified level of stability has been developed. Statistical data on the reaction of the information protection system are analyzed. Conclusions are drawn about the effectiveness of the developed information protection system in the corporate network.

A General Framework for Voltage Sag Performance Analysis of Distribution Networks

The proliferation of more sensitive loads has obliged distribution companies to pay greater attention to the voltage sag mitigation potential of different design alternatives in network planning studies. In doing so, a company has to have effective tools for estimating the voltage sag performance of its network. In this regard, this paper establishes a three-step framework for evaluating voltage sag performance of a distribution network. The first step, designated as state selection, is to select a network state in which voltage sag is likely. Although voltage sags have various causes, those that originated from faults in distribution networks are considered in this paper. The stochastic nature of fault location, type, resistance, and duration as well as the response of the protection system are taken into account. The second step, called state evaluation, deals with sag characteristics during the fault clearing time and the protection system response. The third step, named index calculation, is to estimate indices reflecting the sag performance of the network. A number of indices are proposed in this paper to reflect both system and load point-oriented issues. In light of the indices, companies may find effective solutions for voltage sag mitigation and customers choose appropriate solutions to provide ride-through support for their critical processes.

Реализация защит от аварийных режимов в электроприводе вентиляторов малой мощности

The paper deals with the design of an inverter supplying power to the drive of fans cooling the subway car brake resistors and the traction electric drive power converter’s heat sink fins. Since this fan drive is a low-capacity one, it was decided to make the inverter for it with the minimal possible cost. To achieve the desired objective, it was decided to exclude protections from certain very unlikely emergency modes. It was proposed to use cheap IC chips of transistor switch drivers and to implement short-circuit protection using current transformers. The current transformers have a very large bandwidth and can be used in the application in question not only to protect the motor, but also to protect the inverter transistor switches. The current transformer signals are rectified by a low-capacity rectifier, thus making it possible to eliminate separate processing of the phase current positive and negative half-waves. The rectified signals are fed to the input of the protection circuit implemented on operational amplifiers. The total time of short-circuit protection system response to the input signal is about 1 μs. In measuring the current transformers’ output signals, it is possible to obtain a sufficient amount of data for making overload protection, phase open-circuit fault protection, load imbalance protection, and thermal protection. Emergency modes detection algorithms for implementing them in the scope of the electric drive microprocessor control system are presented. The proposed solutions were investigated on a mathematical model and on the inverter mockup prototype, and the obtained results have demonstrated their efficiency. &nbsp

Reconstruction of Aerothermal Environment and Heat Shield Response of Mars Science Laboratory

An initial assessment and reconstruction of the Mars Science Laboratory entry aerothermal environment and thermal protection system response is performed using the onboard instrumentation suite called the Mars Science Laboratory entry, descent, and landing instrumentation. The analysis is performed using the current best-estimated trajectory. The Mars Science Laboratory Entry, Descent, and Landing Instrumentation suite in part provides in-depth temperature measurements at seven locations on the heat shield. The temperature data show the occurrence of boundary-layer transition to turbulence on the leeside forebody of the entry vehicle. The data also suggest that the thermal protection system recession is lower than nominal model predictions using diffusion limited surface oxidation. The model predictions of temperatures show an underprediction in the stagnation and apex regions and an overprediction in the leeside region. An estimate of time-varying aeroheating using an inverse reconstruction technique is also presented. The reconstructed aeroheating is sensitive to the choice of a recession model. A few areas of excess margins in aerothermal environments and thermal protection system sizing are identified for reevaluation in future designs.

Studying the development of asynchronous rolling of the rotor over the stator with the turbine unit protection systems having different response times

The possibility to stabilize the developing asynchronous rolling of the rotor over the stator under the conditions of power unit protections coming in action with different response times is considered. Asynchronous rolling of the rotor over the stator may develop when the rotating rotor comes in contact with the stator at high amplitudes of vibration caused by an abrupt loss of rotor balancing, by forced or self-excited vibration of the rotor, and by other factors. The danger of asynchronous rolling is connected with almost instantaneous development of self-excited vibration of the rotor when it comes in contact with the stator and with the rotor vibration amplitudes and forces of interaction between the rotor and stator dangerous for the turbine unit integrity. It is assumed that the turbine unit protection systems come in action after the arrival of signal of exceeding the permissible vibration level and produce commands to disconnect the generator from the grid, and to stop the supply of working fluid into the flow path, due to which an accelerating torque ceases to act on the turbine unit shaft. The protection system response speed is determined by a certain time t = ABtime that is taken for its components to come in action from the commencement of the event (application of the signal) to closure of the stop valves. The time curves of the main rolling parameters as functions of the ABtime value are presented. It is shown that the response time of existing protection systems is not sufficient for efficiently damping the rolling phenomenon, although the use of an electrical protection system (with the response time equal to 0.40–0.45 s) may have a positive effect on stabilizing the vibration amplitudes to a certain extent during the rolling and on smoothing its dangerous consequences. The consequences of rotor rolling over the stator can be efficiently mitigated by increasing the energy losses in the rotor-stator system (especially in the stator) and by fulfilling the recommendations of the machinery unit catastrophe prevention system.

Inadequate housing and the child protection system response

Involvement with child protective services (CPS) is common among families experiencing inadequate housing conditions. As with other issues of material deprivation, inadequate housing is an area where the distinction between neglect and poverty is difficult to ascertain, and the response of the child protection system to inadequately-housed families is largely understudied. This study uses a nationally representative sample of child protection investigations to explore the associations between two types of inadequate housing—doubling up and experiences of homelessness—and system outcomes. Specially, we identify that, after accounting for other risk factors, inadequate housing is significantly associated with the receipt of services, but not directly associated with either substantiation or case closure. Moreover, housing concerns may have a different association with case outcomes when interacted with other risk factors, specifically mental health and substance abuse, and domestic violence. Overall, results suggest that, while child protection workers do not view inadequate housing as neglect in and of itself, they do identify housing issues as a service need.

Postflight Thermal Protection System Analysis of Hayabusa Reentry Capsule

The thermal response of the ablative thermal protection system of the Hayabusa capsule is calculated along the most probable reentry trajectory by using the integrated analysis method. The analysis method consists of an axisymmetric nonequilibrium Navier–Stokes flow solver and a radiative heat transfer analysis code loosely coupled to an ablation thermal response code. The calculated results are compared with the flight data obtained at the present time. It is found that a reasonable agreement is obtained between the calculated surface temperature and the temperature values estimated from the DC-8 airborne observation and the ground observation. In contrast, the calculated surface recession overestimates the measurement along the wall surface by a factor of three. It is also found that the density distributions inside the ablator can be reproduced reasonably both at the stagnation point and at the downstream region by taking account of the conventional surface reaction set and nitridation reaction with a laminar boundary condition. Especially for the thickness of the char layer at the downstream region, calculation overestimates the flight data when the effect of turbulence due to the pyrolysis gas is considered, whereas it underestimates the flight data when the effect of surface roughness of the ablative thermal protection system is taken into account.

Loss and reliability optimization for power distribution system operation

This study presents an optimization method that combines simultaneously the reliability and the efficiency of radial power distribution systems (RDS), minimizing active energy losses, through a process of network reconfiguration. The study is based on the failure analysis on network branches, with a special concern regarding the protection system response to faults and the service restoration procedures, during the emergency state. A non-sequential Monte Carlo simulation based on the branch reliability was used to evaluate reliability of the network configurations. Due to a large number of possible configurations and the need of an efficient search, the optimization is made through an improved genetic algorithm (IGA). The method analyses the RDS considering in a first step, the absence of investment, and in a second step, the possibility of placing a limited number of new tie-switches in certain branches, according to the definitions made by a decision maker. The effectiveness of the proposed methodology is demonstrated through the analysis of a 69 bus RDS and by comparison against other reported methodologies.

A nonlinear binary programming model for electric distribution systems reliability optimization

This paper presents a new nonlinear binary programming model aiming to minimize the SAIDI and SAIFI reliability indices of a distribution feeder. Graph theory and a contingency simulation-based technique are used in the explicit formulation of the objective functions to accurately model the protection system response to faults and system reconfiguration practices. To ensure the solution’s feasibility both technical and economic constraints are considered. An alternative economic constraint is proposed, taking into account the current locations of the protective devices and sectionalizing switches, which directly affect the utility costs for reliability improvement. To solve the proposed model, an optimization technique based on the branch-and-bound algorithm is used in this paper. Hence, this technique enables deterministic optimization of distribution feeder reliability by identifying types and locations of protection devices and sectionalizing switches, so that SAIDI and SAIFI reliability indices are minimized. Test cases are presented to illustrate the reliability optimization of a test feeder considering the use of different protection schemes and cost constraints. A value-based reliability optimization formulation is derived from the proposed model and its application to the test feeder is also illustrated. Additionally, the solutions obtained from the proposed model are compared with the solutions obtained from two other state-of-the-art models found in the literature. A comparative study is also carried out to evaluate the efficiency of the genetic algorithm in solving the proposed models.

Hybrid system based on constructive heuristic and integer programming for the solution of problems of fault section estimation and alarm processing in power systems

This paper presents a tool capable of performing alarms processing to diagnose faults in electrical power systems. The purpose is to filter alarms generated during a shutdown and indicate which equipment is at fault. To solve this problem, it was proposed an integrated use between constructive heuristic methods (CH) and integer programming (IP) by establishing a methodology for its completion. Initially, CH method performs through alarms signaled by protective relays, an analysis with relation to direction of fault in each equipment of power system. Thus, CH in possession of as much information as possible, and signals coming from trip of each relay equipment (busbars, power transformers and transmission lines), can identify direction in which disturbance occurred. The final processing is done by IP, which analyzes the response of protection system as a whole, using signs of opening triggers of circuit breakers along with response of CH, indicating at fault section and possible failures of opening in circuit breaker.