Efficient Protection Scheme Research Articles

Efficient unequal error protection for online fountain codes

In this paper, an efficient unequal error protection (UEP) scheme for online fountain codes is proposed. In the buildup phase, the traversing-selection strategy is proposed to select the most important symbols (MIS). Then, in the completion phase, the weighted-selection strategy is applied to provide low overhead. The performance of the proposed scheme is analyzed and compared with the existing UEP online fountain scheme. Simulation results show that in terms of MIS and the least important symbols (LIS), when the bit error ratio is 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−4</sup> , the proposed scheme can achieve 85% and 31.58% overhead reduction, respectively.

Optimal Security Protection Strategy Selection Model Based on Q-Learning Particle Swarm Optimization.

With the rapid development of Industrial Internet of Things technology, the industrial control system (ICS) faces more and more security threats, which may lead to serious risks and extensive damage. Naturally, it is particularly important to construct efficient, robust, and low-cost protection strategies for ICS. However, how to construct an objective function of optimal security protection strategy considering both the security risk and protection cost, and to find the optimal solution, are all significant challenges. In this paper, we propose an optimal security protection strategy selection model and develop an optimization framework based on Q-Learning particle swarm optimization (QLPSO). The model performs security risk assessment of ICS by introducing the protection strategy into the Bayesian attack graph. The QLPSO adopts the Q-Learning to improve the local optimum, insufficient diversity, and low precision of the PSO algorithm. Simulations are performed on a water distribution ICS, and the results verify the validity and feasibility of our proposed model and the QLPSO algorithm.

A multidisciplinary integrated approach using Pachygrapsus marmoratus to assess the impact of port activities on mediterranean marine protected areas

The establishment of marine protected areas is considered the main global strategy to halt the loss of marine biodiversity. Since most of marine areas are open systems, this form of habitat protection cannot prevent their contamination due to human activities performed outside of their borders. Innovative approaches to assess the health status of protected marine habitats are therefore needed. Here we developed a multidisciplinary approach that combines ecological characteristics, bioaccumulation of inorganic and organic pollutants, cell damage (micronuclei frequency, nuclear alterations and LPO) and enzymatic (AChE, CAT, IDH, LDH, GST and CAT) markers focused on an intertidal brachyuran crab, Pachygrapsus marmoratus, to assess the impacts of contaminant exposure on Mediterranean coastal habitats. As study sites we selected two protected areas and two sites within industrial ports of the Ligurian Sea. Our results showed that the selected crab species is an excellent bioindicator. Individuals collected in sites with the highest levels of heavy metal pollution showed the highest signals of stress responses at both cellular and enzymatic levels, coupled with a high incidence of the parasite Sacculina carcini, a signal of impairment of their standard development and reproduction cycle. We could also prove that one of the selected marine protected areas showed the same intensity of impact as its adjacent port site. Our multidisciplinary approach proved to be a valuable tool to assess the environmental quality and health of protected and disturbed Mediterranean coastal environments and to inform efficient management and protection schemes for such habitats.

Tradeoffs between optimality and equity in transportation network protection against sea level rise

Transportation equity is an essential aspect of urban transportation planning. With climate change becoming inevitable, coastal cities are considering the mitigation of the impact of sea level rise on infrastructure. Transportation equity and sea level rise adaptation are usually considered separately. However, research pointed out that these two challenges could have considerable overlap and interaction. The present paper discusses transportation equity issues resulting from the impact of sea level rise and associated protection strategies. A case study of the San Francisco Bay Area points out cases where transportation equity can be negatively impacted when the optimal protection strategy against sea level rise is implemented. An integrated hydrodynamic and transportation model system is used in the present paper to demonstrate several scenarios where the most efficient protection strategies for the whole region increase the inequity that exists between the disadvantaged communities and other communities. Nevertheless, this impact can be mitigated with a relatively small addition to the protection strategy. The paper suggests that transportation equity cannot be overlooked in planning climate adaptation, as even the protection plan that maximizes benefits for the region may negatively impact the most vulnerable communities.

Strategy to Construct High Thermal‐Stability Narrow‐Band Green‐Emitting Si‐CDs@MAs Phosphor for Wide‐Color‐Gamut Backlight Displays

AbstractDeveloping innovative narrow‐band green‐emitting phosphors featuring low thermal quenching and eco‐friendliness for white light‐emitting diode (WLED) backlights is a pivotal challenge. Benefitting from narrowband and low toxicity of green‐emitting silanized carbon dots (Si‐CDs), an efficient confinement and protection strategy through embedding Si‐CDs in mesoporous aluminas (MAs) is proposed to construct MAs and Si‐CDs composites (Si‐CDs@MAs) with superior luminescence properties. Si‐CDs@MAs phosphor exhibits green emission at 526 nm with narrow full width at half maximum of 51 nm, zero‐thermal quenching even up to 423 K (104.1%@423 K of the emission peak intensity at 298 K), and the internal quantum efficiency of 64.46%. Compared with broad‐band yellow‐emitting solid‐state Si‐CDs (S‐Si‐CDs), the thermal stability, photostability, and water stability of Si‐CDs@MAs phosphor are remarkably improved due to surface protection. The WLED backlight is fabricated with optimized Si‐CDs@MAs phosphor, which shows high luminous efficacy of 117.43 lm W−1and wide color gamut (107% NTSC). Furthermore, this work provides the design principles of realizing stable narrow‐band solid‐state fluorescence carbon dots, suggesting its great potential for wide‐color‐gamut display application.

Failure analysis of unmanned autonomous swarm considering cascading effects

In this paper, we focus on the failure analysis of unmanned autonomous swarm (UAS) considering cascading effects. A framework of failure analysis for UAS is proposed. Guided by the framework, the failure analysis of UAS with crash fault agents is performed. Resilience is used to analyze the processes of cascading failure and self-repair of UAS. Through simulation studies, we reveal the pivotal relationship between resilience, the swarm size, and the percentage of failed agents. The simulation results show that the swarm size does not affect the cascading failure process but has much influence on the process of self-repair and the final performance of the swarm. The results also reveal a tipping point exists in the swarm. Mean-while, we get a counter-intuitive result that larger-scale UAS loses more resilience in the case of a small percentage of failed individuals, suggesting that the increasing swarm size does not necessarily lead to high resilience. It is also found that the temporal degree failure strategy performs much more harmfully to the resilience of swarm systems than the random failure. Our work can provide new insights into the mechanisms of swarm collapse, help build more robust UAS, and develop more efficient failure or protection strategies.

Efficient Protection of Silver Nanowire Transparent Electrodes by All-Biorenewable Layer-by-Layer Assembled Thin Films.

An efficient protection strategy for silver nanowire-based transparent electrodes (AgNW TEs) is developed to enhance their poor adhesion force on substrates and thermal, optical, chemical, and electrical stabilities. Chitin nanofibers (CNFs) and alkali lignin (AL), which possess high mechanical property, a gas/moisture barrier, and UV absorption properties, are successively assembled on AgNW TEs through layer-by-layer (LBL) assembly based on their oppositely charged surfaces. The formation of LBL-assembled CNFs and AL (CNF/AL)10 bilayers, where 10 is the optimized number of bilayers, on the aldehyde-modified AgNW (Al-AgNW) TEs does not deteriorate their electrical conductivity (17.3 ± 2.1 Ω/□) and transmittance (90.1 ± 0.3% at 550 nm), and the (CNF/AL)10 bilayer-coated Al-AgNW [(CNF/AL)10@Al-AgNW] TEs present considerable enhancement in their adhesion force and thermal, optical, chemical, and electrical durability. In detail, their optoelectrical properties are stable over 200 cycles of the scotch peel-off test, for 10 h sonication, up to 350 °C, under UV/O3 treatment for 100 min, in 10% HCl and 28% NH3 for 6 and 12 h, and at an electrical potential up to 14 V, respectively. These features make (CNF/AL)10@Al-AgNW TEs suitable as a durable high-performance transparent heater.

Enhancing adhesion and anti-corrosion performance of hot-dip galvanized steels by sandblasting/phosphating co-treatment

The substations outdoor steel structures employed in aggressive marine environments can accelerate corrosion damage and cause incredible degradation of performance. Hot-dip galvanizing and organic coating dual-coated anticorrosion system is currently the most effective and efficient protection strategy. In present paper, sandblasting and phosphating technique were applied to the surface of zinc plating, the effect of various grit-blasting and phosphating technology conditions on the adhesion performance and corrosion resistance of duplex-coated system were systematically investigated. Results revealed that the bonding strength of the duplex coating after grit-blasting and phosphating pretreatment was 3.25 and 2.71 times higher than that of the untreated, respectively. In particular, sandblasting and phosphating coprocessing of duplex coating could furtherly improve the adhesion behavior and corrosion resistance, which mainly due to their synergistic effect. Sandblasting can rough the surface of galvanized coating and generate many pits and scratches. Thus, phosphating can form more needle-like zinc phosphate crystals in those positions, anchoring and pinning firmly the interface between galvanized coating and organic coating. Meanwhile, the phosphating film still acted as an anti-corrosion physical barrier to hinder the intrusion of corrosive medium and protect galvanized steels from storage rust before painting for a long time.

Disaster Protection in Inter-DataCenter Networks Leveraging Cooperative Storage

Natural disasters have challenged the survivability of Elastic Optical Inter-DataCenter Networks (EO-DCNs), and it is urgent to establish efficient disaster protection schemes. In this paper, we investigate the disaster-resilient service provisioning problem leveraging cooperative storage system (CSS). Instead of mirrored content backup on a single DC, our proposed CSS partitions a required content into no less than three fragments if possible, each of which is then stored on a DC located in different disaster zones. Accordingly, multi-path routing with the adaptive number of working paths to distinct DCs is employed to serve each request, while a protection path is computed to protect against a disaster failure. Our main objective is to jointly minimize the spectrum usage and maximal occupied frequency slot index (MOFI) subject to disaster resilience. Besides, we also expect to cut the content storage space. To this end, we propose for the first time a CSS-based dedicated end-to-content path protection (CDP), which allows service provisioning through multiple paths with the adaptive number of paths rather than a single path. This consequently reduces at least half of the reserved spectrum on the protection path. To find the optimal CDP strategy, we formulate the studied problem as an integer linear program (ILP) and then propose a fast heuristic algorithm. Observing the trade-off between the spectrum usage and content storage space, we further design a maximum-CDP (M-CDP), which generates the maximum number of working paths to reduce the content storage space. Simulations are conducted to compare the proposed schemes with the traditional protection strategy using mirrored storage and single-path routing. Numerical results demonstrate that the proposed CSS-based protection schemes enable to cut up to 21.6% of the spectrum usage and 15% of the content storage space.

AC Microgrids Protection: A Digital Coordinated Adaptive Scheme

A significant challenge for designing a coordinated and effective protection architecture of a microgrid (MG) is the aim of an efficient, reliable, and fast protection scheme for both the grid-connected and islanded modes of operation. To this end, bidirectional power flow, varying short-circuit power, low voltage ride-through (LVRT) capability, and the plug-and-play characteristics of distributed generation units (DGUs), which are key issues in a MG system must be considered; otherwise, a mal-operation of protection devices (PDs) may occur. In this sense, a conventional protection system with a single threshold/setting may not be able to fully protect an MG system. To tackle this challenge, this work presents a comprehensive coordinated adaptive protection scheme for AC MGs that can tune their protection setting according to the system states and the operation mode, and is able to switch the PDs’ setting. In the first step of the proposed adaptive algorithm, an offline setting will be adopted for selective and sensitive fault detection, isolation, and coordination among proposed protective modules. As any change in the system is detected by the proposed algorithm in the online step, a new set of setting for proposed modules will be performed to adapt the settings accordingly. In this way, a new set of settings are adapted to maintain a fast and reliable operation, which covers selective, sensitive, and adaptive requirements. The pickup current (Ip) and time multiple settings (TMS) of directional over-current relays (DOCR), as well as coordinated time delays for the proposed protection scheme for both of the grid-connected and islanded modes of operation, are calculated offline. Then, an online adaptive protection scheme is proposed to detect different fault types in different locations. The simulation results show that the proposed method provides a coordinated reliable solution, which can detect and isolate fault conditions in a fast, selective and coordinated adaptive pattern.

Multi‐agent based protection scheme using current‐only directional overcurrent relays for looped/meshed distribution systems

The complexity of the design of the protection system using directional over current relays, for modern power distribution systems has been increased due to the looped/meshed operation and the penetration of distributed generations. Finding a reliable and efficient protection scheme that can be easily implemented in these distribution systems is a major challenge. An efficient solution could be the use of artificial intelligent-based multi-agent systems. This paper proposes a novel distributed intelligent based multi-agent protection scheme, which makes use of current-only directional over current relays as agents for detecting and locating faults and isolating faulty areas (lines/busbars) in the distribution systems. All agents can make on-board decisions by exchanging binary data, and do not need a control centre, so the safety of the protection system against one-point failures and cyber-attacks is increased. The proposed scheme does not need to exchange analogue data, and, therefore, it prevents the high bandwidth communication links. Moreover, it is free from the traditional coordination between relays. This scheme is implemented on the IEEE-14 bus and IEEE-30 bus test systems with the distributed generations and several scenarios have been simulated to evaluate its performance.

Fine Spatial Scale, Frequent Morphological Monitoring of Urbanised Beaches to Improve Coastal Management

Between 1959 and 2010, a coastline retreat of 2.4 m/year and erosion of up to 174 m were recorded around Turbo, in northern Colombia. This degraded coastal system is the result of a poorly planned coastal defence scheme, combined with a lack of formal technical methodologies for diagnosis and monitoring. The coastal system cannot provide the protection services required by the local community. From 2017 to 2019, the group monitored urban beach profiles in a small area close to the town of Turbo, in the wet and the dry seasons, as part of a coastline analysis to identify morphodynamic trends in the area. The results show a net shoreline accretion of up to 30 m and positive sedimentary accumulation of up to 45.8 m3/m. To the north of the study area, sediment accumulation is evident at the Turbo River Delta. The 34 coastal protection structures in the study area have a high k index (~0.7), suggesting that they are the main drivers controlling the trend of sediment accumulation. The correlation of geomorphological, oceanographic, and anthropic variables related to the presence of coastal structures, is necessary in order to set up efficient coastal protection schemes.

EC-BAAS: Elliptic curve-based batch anonymous authentication scheme for Internet of Vehicles

As an indispensable part of intelligent transportation systems, Internet of Vehicles (IoV) has been widely used in improving the driving experience and road conditions. In the communication of IoV, the security of transmitted messages is critical. Specifically, the messages should be signed and verified before they are accepted by vehicles or road side units. To ensure the privacy of vehicle users, the vehicles’ true identity cannot be leaked. Moreover, considering the high dynamics and open environments of IoV, it is very important to design an efficient anonymous authentication scheme on the basis of security. However, most of the existing schemes struggle with the problems of insufficient security performance and low efficiency. This motivates us to propose a safe and efficient privacy protection scheme for IoV. The proposed scheme is a new batch anonymous authentication scheme designed based on the elliptic curve encryption algorithm, considering both security and efficiency. A distributed signature generation method is also developed in the proposed scheme to relieve the burden of the trusted center. In addition, our scheme can effectively track illegal vehicles and achieve conditional privacy protection. Theoretical analysis and performance evaluation are both carried out to validate our scheme. The results show that our scheme ensures competitive security performance with lower communication and computation overheads compared to representative approaches.

Cyber‐physical component ranking for risk sensitivity analysis using betweenness centrality

This article proposes a model for critical component ranking in power system risk analysis using a proposed cyber-physical betweenness centrality (CPBC) index. Risk assessment, as part of the contingency analysis, is a critical activity that can identify and evaluate component outages that lead to system vulnerability, aiding operators to improve resilience. A power system cyber-physical risk assessment model is proposed that calculates and offers an efficient protection strategy to the system operator based on component vulnerability to adversaries and the impact of compromised assets on the system operation. We present the CPBC index, which traverses generated attack graphs to rank components according to their importance in reducing adversary impact on the power system. The CPBC extends upon betweenness centrality and integrates into analysis, the services and security cost of communications between system components, as well as the likelihood of component exploitation as an adversary medium to the target relays. The proposed model recommends actions, taking into account the interconnections between cyber and physical components as well as cyber-induced Common Vulnerabilities and Exposure scores associated with these connections, thus protecting critical components. The proposed model is implemented on the Cyber-Physical Situational Awareness 8-substation and extended IEEE 300-bus cyber-physical power system models, and results are presented on the impacts of the proposed component ranking model on the security-aware operation of the power system.

Efficient Protection Scheme Based on Y-Source Circuit Breaker in Bi-Directional Zones for MVDC Micro-Grids

A new bi-directional circuit breaker is presented for medium-voltage dc (MVDC) systems. The Y-source impedance network topology is used to implement the breaker. The current transfer function is derived to show the frequency response and the breaker operation with the high frequencies. Mathematical analysis is achieved with different conditions of coupling among the breaker inductors. The minimum level of the magnetic coupling is determined, which is represented by the null condition. The effect of the turns-ratio on this condition is investigated as well. The breaker is designed with two types of fault conductance slope rates. The Y-source breaker is simulated, and the results verify the breaker operation during the fault condition and the load change. The results also demonstrate the effect of the coupling level on the minimum values of the source current when the fault occurs. Based on the expected fault type in the MVDC systems, the proposed breaker is developed to interrupt the overcurrent due to any of these fault types. A protection scheme is proposed for a 12-bus, two-level micro-grid, where the Y-source breakers are used in the bi-directional zones. The results verify the ability of the breaker to conduct and interrupt the current in both directions of the power flow.

Selective Neuron Re-Computation (SNRC) for Error-Tolerant Neural Networks

Artificial Neural networks (ANNs) are widely used to solve classification problems for many machine learning applications. When errors occur in the computational units of an ANN implementation due to for example radiation effects, the result of an arithmetic operation can be changed, and therefore, the predicted classification class may be erroneously affected. This is not acceptable when ANNs are used in many safety-critical applications, because the incorrect classification may result in a system failure. Existing error-tolerant techniques usually rely on physically replicating parts of the ANN implementation or incurring in a significant computation overhead. Therefore, efficient protection schemes are needed for ANNs that are run on a processor and used in resource-limited platforms. A technique referred to as Selective Neuron Re-Computation (SNRC), is proposed in this paper. As per the ANN structure and algorithmic properties, SNRC can identify the cases in which the errors have no impact on the outcome; therefore, errors only need to be handled by re-computation when the classification result is detected as unreliable. Compared with existing temporal redundancy-based protection schemes, SNRC saves more than 60 percent of the re-computation (more than 90 percent in many cases) overhead to achieve complete error protection as assessed over a wide range of datasets. Different activation functions are also evaluated.

Considering the tap-changing modifications in protection of EAF transformers

This paper deals with the modeling of EAF feeding system taking into account the tap transition for assessment of a suggested scheme of differential protection. There are several challenges in the implementation of the differential protection in the EAF transformer which reveal the importance of the system modeling. Large current in the secondary side of the transformer, similarity of normal and fault conditions, and frequent tap variation in the transformer during the melting procedure are the most serious concerns. Considering the mechanism of the tap changers, the new tap setting is readjusted in the algorithm to prevent mal-operation of the protection. These challenges can be rectified by suitable modeling of EAF feeding system and an efficient differential protection scheme. To this end, the EAF as an electrical load, the EAFs' transformer, and the mechanism of the tap changing are properly modeled in this work. The proposed model of the EAF is based on real recorded data from EAFs used in a steel company, to fully simulate the nonlinear and time-variant characteristics of this electrical load. The proposed models of the EAFs' transformer and tap changer enable us to simulate different tap variations and internal faults in the system. The performance of the suggested differential protection algorithm is evaluated using plenty of simulations in different conditions of the system.

Blue Light and the Skin.

In photodermatology, UV radiation is the component of the solar system that has attracted the most interest as it represents the greatest risk of skin damage from solar exposure. Efficient protection strategies have therefore been developed to protect skin against powerful solar radiation. Recently, there has been increasing evidence to suggest that less energetic radiation, such as visible light and infrared radiation, might also influence skin physiology. Yet, it remains unclear, regarding risk assessment, whether visible light irradiation induces positive or negative effects in skin and when appropriate protection is needed. This review focuses primarily on blue light as part of the visible spectrum and sets out current mechanistic understanding of the benefits and risks of blue-light exposure to skin. Furthermore, it discusses phototherapies and potential strategies for protecting against detrimental effects of blue light such as hyperpigmentation and premature skin aging.

Regional economic analysis of flood defence heights at the German Baltic Sea coast: A multi-method cost-benefit approach for flood prevention

Mean and extreme sea-level uncertainties, as well as uncertainty about future flood exposure, hinder the risk-based optimisation of flood protection investments. To deal with these uncertainties, cost-benefit analysis (CBA) and methods for robust decision-making can be combined. This paper sequentially applies CBA, robust optimisation methods and info-gap analysis to find efficient and robust coastal flood protection strategies for the German Baltic Sea coast. The CBA results suggest that – under flood risk assumptions – a share of the coast of Schleswig-Holstein (9.3–10.1%; 60–65 km) and Mecklenburg-Vorpommern (4.1–10.0%; 78–189 km) with relatively high flood exposure, might currently be under-protected from a social welfare perspective. Present Value estimates of regional investment costs of five regret or loss minimising strategies range from 1.7 to 4.8 billion Euro across robustness metrics at 3% discounting. The info-gap analysis suggests that some of these strategies will fail to prevent large-scale damages under high-end scenarios. We conclude that a multi-method cost-benefit approach can be used to narrow down the number of solutions that are both potentially efficient and sufficiently robust by investigating strategy performance within, across and beyond predefined scenarios.

Nanoscale Encapsulation of Perovskite Nanocrystal Luminescent Films via Plasma-Enhanced SiO2 Atomic Layer Deposition.

Photoluminescence perovskite nanocrystals (NCs) have shown significant potential in optoelectronic applications in view of their narrow band emission with high photoluminescence quantum yields and color tunability. The main obstacle for practical applications is to obtain high durability against an external environment. In this work, a low temperature (50 °C) plasma-enhanced atomic layer deposition (PE-ALD) protection strategy was developed to stabilize CsPbBr3 NCs. Silica was employed as the encapsulation layer because of its excellent light transmission performance and water corrosion resistance. The growth mechanism of inorganic SiO2 via PE-ALD was investigated in detail. The Si precursor bis(diethylamino)silane (BDEAS) reacted with the hydroxyl groups (-OH) and thereby initiated the subsequent silica growth while having minimal influence to the organic ligands and did not cause PL quenching. Subsequently, O2 plasma with high reactivity was used to oxidize the amine ligands of the BDEAS precursor while did not etch the NCs. The obtained CsPbBr3 NCs/SiO2 film exhibited exceptional stability in water, light, and heat as compared to the pristine NC film. Based on this method, a white light-emitting diode with improved operational stability was successfully fabricated, which exhibited a wide color gamut (∼126% of the National Television Standard Committee). Our work successfully demonstrates an efficient protection scheme via the PE-ALD method, which extends the applied range of other materials for stabilization of perovskite NCs through this approach.