Fast Resilience Research Articles

Tunable temperature-responsive photonic ionogels with dual signals output

Photonic ionogels with dual electrical and optical output have been intensively studied. However, tunable temperature-responsive photonic ionogel assembled by thermosensitive nanogels has not been studied yet. Herein, an innovative approach to fabricate photonic ionogels has been developed for smart wearable devices with tunable temperature sensitivity and structural color. Firstly, poly(isopropylacrylamide-r-phenylmaleanilic acid) P(NIPAm-r-NPMA) nanogels self-assemble into photonic crystals in 2-hydroxyethyl acrylate (HEA), water, and the ionic liquid of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate. And then robust photonic ionogels are developed through a polymerization of 2-hydroxyethyl acrylate crosslinked by poly(ethylene glycol) diacrylate (PEGDA). The incorporation of the ionic liquid, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, enhances the mechanical strength of photonic ionogels and tunes the temperature-sensitivity of the ionogels, making them adaptable to various environmental conditions. The findings demonstrate that these ionogels can serve dual functions in smart wearable devices, combining electrical and optical signal outputs due to the conductivity of the ionic liquid and structural color from the nanogel assembly. The resultant photonic ionogels exhibit exceptional substrate adhesion, mechanical stability, and fast resilience. More significantly, the nanogels within these ionogels serve as the building blocks of photonic crystals (PCs) endow with angle-independent coloration and enhance stretchability beyond 200 %, while the stretchability of the ionogles without the nanogels is only about 100 %. Our photonic ionogels with tunable temperature-sensitivity and dual outputs will open an avenue to the development of the innovative smart wearable devices.

Fast Resilience Assessment of Integrated Electricity-Gas Systems Considering Non-Convex Gas Flow Dynamics

Fast Resilience Assessment of Integrated Electricity-Gas Systems Considering Non-Convex Gas Flow Dynamics

Does the Prohibition of Trade-Through Hurt Liquidity Demanders?

The Impact of the Prohibition of Trade-through In the paper titled “Does the Prohibition of Trade-Through Hurt Liquidity Demanders?” the authors explore the effects of the order protect rule (OPR) in the United States, which prohibits any trade-through in the stock market that does not execute at the best possible price among fast trading venues. The study found that, whereas trade-throughs may offer flexible trading strategies that can benefit liquidity demanders, the benefits are insignificant for most cases, especially for small trades and stocks with fast resilience. The paper suggests that the current separate regulations for fast and slow venues may be extended to differentiate stocks with fast and slow resilience speeds. The results are supported by a case study using the data from the Australian Securities Exchange. Overall, this study supports the regulation of the OPR.

Blockchain based holistic trust management protocol for ubiquitous and pervasive IoT network

ABSTRACT The new emerging blockchain (BC) technology integrated with the IoT ecosystem revolutionised the IoT world. Classic BC with bitcoin method was realised as very expensive operations difficult to adopt for smart IoT applications; therefore, we integrated IoT network with overlay BC with distributed ledger capability to provide a secure trust management system, which can address access control issues of devices on resources. Further, the R-LEACH protocol followed by the same group urges additional cluster head requirement to establish trust between nodes is not considered in our proposed approach. The main advantage of this method is utilising ledgers for holding the trust and IoT information ensuring tamper-proof data. The miners of blockchain layer perform the trust value calculations based on trust evidence and achieved fast trust convergence, accuracy, and resilience against adversary attacks. Our proposed approach enhances privacy, reliability, availability, and more importantly, sharing and storage of trust information and also followed the consensus mechanism Proof-of-Authority (PoA) to approve the synthesis trust value of related transactions by the pre-authenticated miners/validators, from which we can take more accurate trust-based decisions. Performance results of our blockchain-based trust management approach outperformed literature review trust mechanisms for protecting trust data manipulation against the malicious nodes.

Superelastic, Antifreezing, Antidrying, and Conductive Organohydrogels for Wearable Strain Sensors.

Sensors based on conductive hydrogels have received extensive attention in various fields, such as artificial intelligence, electronic skin, and health monitoring. However, the poor resilience and fatigue resistance, icing, and water loss of traditional hydrogels greatly limit their application. Herein, an ionic conductive organohydrogel (PAC-Zn) was prepared for the first time by copolymerization of cardanol and acrylic acid in water/1,3-butanediol as a binary solvent system. A very small amount of cardanol (1% cardanol of total monomers) could not only significantly improve the tensile strength (∼4 times) and toughness (∼3 times) of PAA but also improve its extensibility. Due to the presence of 1,3-butanediol, PAC-Zn showed outstanding tolerance for freezing (-45 °C) and drying (over 85% moisture retention after 15 days of storage in a 37 °C oven). Compared with ethylene glycol and glycerol as antifreeze agents used in organohydrogels, the addition of 1,3-butanediol endowed the organohydrogel with not only similar frost resistance but also better mechanical performance. Besides, PAC-Zn exhibited fast resilience (almost no hysteresis loop) and excellent antifatigue ability. More importantly, a PAC-Zn organohydrogel-based sensor could detect human motion in real time (wrist, elbow, finger, and knee joints), revealing its fast response, good sensitivity, and stable electromechanical repeatability. In conclusion, the multifunctional PAC-Zn organohydrogel is expected to become a potential and promising candidate in the field of strain sensors under a broad range of environmental temperatures.

Industrial Networks Driven by SDN Technology for Dynamic Fast Resilience

Software-Defined Networking (SDN) provides the prospect of logically centralized management in industrial networks and simplified programming among devices. It also facilitates the reconfiguration of connectivity when there is a network element failure. This paper presents a new Industrial SDN (ISDN) resilience that addresses the gap between two types of resilience: the first is restoration while the second is protection. Using a restoration approach increases the recovery time proportionally to the number of affected flows contrarily to the protection approach which attains the fast recovery. Nevertheless, the protection approach utilizes more flow rules (flow entries) in the switch which in return increments the lookup time taken to discover an appropriate flow entry in the flow table. This can have a negative effect on the end-to-end delay before a failure occurs (in the normal situation). In order to balance both approaches, we propose a Mixed Fast Resilience (MFR) approach to ensure the fast recovery of the primary path without any impact on the end-to-end delay in the normal situation. In the MFR, the SDN controller establishes a new path after failure detection and this is based on flow rules stored in its memory through the dynamic hash table structure as the internal flow table. At that time, it transmits the flow rules to all switches across the appropriate secondary path simultaneously from the failure point to the destination switch. Moreover, these flow rules which correspond to secondary paths are cached in the hash table by considering the current minimum path weight. This strategy leads to reduction in the load at the SDN controller and the calculation time of a new working path. The MFR approach applies the dual primary by considering several metrics such as packet-loss probability, delay, and bandwidth which are the Quality of Service (QoS) requirements for many industrial applications. Thus, we have built a simulation network and conducted an experimental testbed. The results showed that our resilience approach reduces the failure recovery time as opposed to the restoration approaches and is more scalable than a protection approach. In the normal situation, the MFR approach reduces the lookup time and end-to-end delay than a protection approach. Furthermore, the proposed approach improves the performance by minimizing the packet loss even under failing links.

Fast Resilience Assessment of Distribution Systems With a Non-Simulation-Based Method

Traditional simulation-based method for resilience assessment of distribution systems is very time consuming since the network topology is characterized with a large number of scenario-specific optimization models. In this paper, we propose a methodology for fast resilience assessment of distribution systems with a non-simulation-based method, which can significantly improve the assessment accuracy and computational efficiency. First, a probabilistic metric is proposed to assess the system resilience against extreme events, which quantifies the system performance starting from the pre-event stage to the post-event stage. Then, a mixed-integer linear programming (MILP) is proposed to model the energization paths (EPs) with binary decision variables. Subsequently, the resilience metric-related probability events are built using the EPs. Last, the probabilistic resilience metric is explicitly expressed based on the total probability formula, conditional probability formula and EP-topology simplification methods. In the proposed method, the topology evolution along with the system degradation, restoration (part healed) and recovery (all healed) is characterized with a non-simulation-based method, rather than the multiple scenarios in traditional methods. The numerical tests validate the effectiveness of the proposed method and superiority over the simulation-based approach.

Comparative study of gelatin cryogels reinforced with hydroxyapatites with different morphologies and interfacial bonding

Gelatin cryogels are good candidate scaffolds for tissue engineering because of their interconnected macroporous structure. For bone regeneration, inorganic components are chosen to reinforce gelatin cryogels: (i) to mimic the compositions of natural bone tissue and (ii) to meet the mechanical requirements of bone repairing. Cryogels were prepared from methacrylated gelatin (GelMA) in this study, and hydroxyapatite nanorods (HANRs) with surface-grafted acrylate groups (D-HANRs) were synthesized to reinforce the cryogels, in which, the crosslinking between GelMA and D-HANRs was expected. In parallel, HANRs and hydroxyapatite nanowires (HANWs) were also composited with the GelMA cryogels to investigate the effects of filler morphology and interfacial bonding on the overall properties of the resulting composite cryogels comparatively. All these composite cryogels demonstrated potential as bone repairing materials by displaying excellent performances such as high porosity, appropriate water retention, shape recovery, and fast resilience features, as well as good biocompatibility and cell affinity. In comparison with the HANR composited GelMA cryogel, the HANWs were able to ameliorate the compression and the rheology performances of the resulting composite cryogels more efficiently due to the fact that the one-dimensional HANWs played a bridging role in the gelatin matrix. Among all the preparations, however, it was the D-HANRs that achieved the strongest reinforcement efficiency in mechanical properties because the double bonds on their surface could be photo-crosslinked with GelMA to form interfacial bonding. With these findings, we concluded that it was preferable for inorganic fillers designed for cryogel-type bone repairing materials to be in a one-dimensional morphology with surface functional groups to strengthen their interfacial bonding with the polymeric matrix.

Contrasted resistance and resilience of two mangrove forests after exposure to long-term and short-term anthropic disturbances

Mangroves, coastal forests under the influence of tides, are known to be very resilient when they face natural disturbances such as storms or tsunami. While they provide several ecological services, they are threatened by many anthropic pressures. The aim of this study was to assess and to compare the stability of two mangrove fringes defined by contrasted set of natural constraints and exposed to pretreated domestic wastewaters discharges. The in situ experimental system set up in Mayotte Island (Indian Ocean) allowed us to determine both the short-term (2 years) and the long-term (9 years) resistance and the resilience. We focused on vegetation and crabs, an essential component of mangroves fauna. Wastewater discharges induced increases in tree coverage, leaves productivity and pigment content, and a decrease in crab diversity and density. Within 2 years after the release of the disturbance, several parameters reach back control values indicating fast resilience. Our results notably emphasized the high stability of the mangrove fringe dominated by Rhizophora mucronata trees, which was both more resistant and more resilient. This makes this fringe more suitable for application purposes, such as outfall for domestic wastewaters treatment plants.

Grazers superimpose humidity effect on stream biofilm resistance and resilience to dry-rewet stress

Temperate low order streams increasingly experience intermittency and drying due to climate change. In comparison to well-studied Mediterranean streams, drying events in canopied temperate streams occur under higher ambient humidity which probably affects the metabolic response to drying. Previous work on drying sediments (in temperate streams) did not consider the interactions of trophic levels. We hypothesized that preservation of sediment moisture due to high humidity increases resistance to drying in temperate streambed biofilms and fast resilience of biofilm activity after flow resumption. We also expected the presence of macroinvertebrate grazers to modulate the biofilm response to dry-rewet stress. Following a two-level factorial design in 24 microcosms, we tested the effect of drying intensity (moderate and intense) and grazer presence and absence (P. antipodarum) on the activity of biofilm colonizing shallow hyporheic sediment. We measured the community respiration over a drying period of 27 days, a single rewetting event and a follow-up of three days. Grazer presence stimulated biofilm community respiration (CRmic) in the permanently wet control, but decreased biofilm resistance to desiccation (<0.2% of pre-disturbed activity), regardless of drying intensity. In the absence of grazers, higher atmospheric humidity in moderately drying microcosms resulted in maintaining a film of adhesive water and low CRmic (29% of pre-disturbed respiration) until the end of the drying period. After flow resumption, the CRmic increased within 8 h, achieving 79–83% of pre-disturbed respiration (no grazers) and 15–41% (with grazers), respectively. Results show that short dry periods in temperate streams, even under high humidity, impact the streambed biofilm community negatively. The complex response and strong effect of grazer presence indicates that experiments including interactions of trophic levels and settings mimicking environmental factors during dry-rewet stress are needed.

Resilience Control of DC Shipboard Power Systems

Direct current (DC) network has been recognized as a promising technique especially for shipboard power systems (SPSs). Fast resilience control is required for an SPS to survive after faults. Towards this end, this paper proposes the indices of survivability and functionality based on which a two-phase resilience control method is derived. The on / off status of loads is determined in the first phase to maximize survivability, while the functionality of supplying loads are maximized in the second phase. Based on a comprehensive model of a DC-SPS, the two-phase method renders two mixed-integer non-convex problems. To make the problems tractable, we develop second-order-cone-based convex relaxations, thus converting the problems into mixed-integer convex problems. Though this approach does not necessarily guarantee feasible, hence global, solutions to the original nonconvex formulations, we provide additional mild assumptions, which ensures that the convex relaxations are exact when the line constraints are not binding. In the case of inexactness, we provide a simple heuristic approach to ensure feasible solutions. Numerical tests empirically confirm the efficacy of the proposed method.

Bioinspired ultra-stretchable and anti-freezing conductive hydrogel fibers with ordered and reversible polymer chain alignment

High-performance stretchable conductive fibers are desired for the development of stretchable electronic devices. Here we show a simple spinning method to prepare conductive hydrogel fibers with ordered polymer chain alignment that mimics the hierarchically organized structure of spider silk. The as-prepared sodium polyacrylate hydrogel fiber is further coated with a thin layer of polymethyl acrylate to form a core–shell water-resistant MAPAH fiber. Owing to the coexistence and reversible transformation of crystalline and amorphous domains in the fibers, MAPAH fibers exhibit high tensile strength, large stretchability and fast resilience from large strain. MAPAH fiber can serve as a highly stretchable wire with a conductive hydrogel core and an insulating cover. The stretchability and conductivity of the MAPAH fiber are retained at −35 °C, indicating its anti-freezing property. As a prime example of stretchable conductive fibers, MAPAH fibers will shed light on the design of next generation textile-based stretchable electronic devices.

Node Virtualization for IP Level Resilience

For Internet protocol (IP) to evolve into a true carrier-grade transport facility, it needs to support fast resilience out-of-the-box. IP-level failure protection based on the IP fast reroute/loop-free alternates (LFA) specification has become industrial requirement recently. The success of LFA lies in its inherent simplicity, but this comes at the expense of letting certain failure scenarios go unprotected. Realizing full failure coverage with LFA so far has only been possible through completely re-engineering the network around LFA-compliant design patterns. In this paper, we show that attaining high LFA coverage is possible without any alteration to the installed IP infrastructure, by introducing a carefully designed virtual overlay on top of the physical network that provides LFAs to otherwise unprotected routers. Our main contribution is formulating the corresponding resilient IP overlay design problem and providing constructions that can achieve full failure coverage against single link failures by adding at most four virtual nodes to each physical one. We also show that the problem of finding the minimal number of virtual nodes achieving full failure coverage is NP-hard, and thus propose heuristic algorithms that are guaranteed to terminate with a fully protected topology in polynomial time. According to the numerical evaluations the performance of our algorithm is on par with, or even better than, that of previous ones, lending itself as the first practically viable option to build highly resilient IP networks.

Tropical forest restoration: Fast resilience of plant biomass contrasts with slow recovery of stable soil C stocks

Abstract Due to intensifying human disturbance, over half of the world's tropical forests are reforested or afforested secondary forests or plantations. Understanding the resilience of carbon (C) stocks in these forests, and estimating the extent to which they can provide equivalent carbon (C) sequestration and stabilization to the old growth forest they replace, is critical for the global C balance. In this study, we combined estimates of biomass C stocks with a detailed assessment of soil C pools in bare land, Eucalyptus plantation, secondary forest and natural old‐growth forest after over 50 years of forest restoration in a degraded tropical region of South China. We used isotope studies, density fractionation and physical fractionation to determine the age and stability of soil C pools at different soil depths. After 52 years, the secondary forests had equivalent biomass C stocks to natural forest, whereas soil C stocks were still much higher in natural forest (97.42 t/ha) than in secondary forest (58.75 t/ha) or Eucalyptus plantation (38.99 t/ha) and lowest in bare land (19.9 t/ha). Analysis of δ13C values revealed that most of the C in the soil surface horizons in the secondary forest was new C, with a limited increase of more recalcitrant old C, and limited accumulation of C in deeper soil horizons. However, occlusion of C in microaggregates in the surface soil layer was similar across forested sites, which suggests that there is great potential for additional soil C sequestration and stabilization in the secondary forest and Eucalyptus plantation. Collectively, our results demonstrate that reforestation on degraded tropical land can restore biomass C and surface soil C stocks within a few decades, but much longer recovery times are needed to restore recalcitrant C pools and C stocks at depth. Repeated harvesting and disturbance in rotation plantations had a substantial negative impact on the recovery of soil C stocks. We suggest that current calculations of soil C in secondary tropical forests (e.g. IPCC Guidelines for National Greenhouse Gas Inventories) could overestimate soil C sequestration and stabilization levels in secondary forests and plantations. A plain language summary is available for this article.

Does the Prohibition of Trade-Through Hurt Liquidity Demanders?

The Order Protect Rule in the U.S. generally prohibits any trade-through, i.e., a market order that is not executed at the best possible price among fast (i.e. electronic and automated) trading venues. We conduct a counterfactual analysis comparing the order execution costs of a liquidity demander when trade-through is allowed versus prohibited. By deriving upper and lower bounds for the costs, we find that the trade-through benefit is marginal for small trades and stocks with fast resilience. In particular, our study suggests that the current separate regulations for fast and slow venues may be extended to differentiate stocks with fast and slow resilience speeds.

Experimental investigation on reparability of an infilled rocking wall frame structure

SummaryImproving seismic performance is one of the critical objectives in earthquake engineering. With the development of economy and society, reparability and fast resilience of a structure are becoming increasingly important. Reinforced concrete (RC) frame structure is prone to soft story mechanism. As a result, deformation and damage are so concentrated that reparability is severely hampered. Rocking wall provides an available approach for deformation control in RC frame by introducing a continuous component along the height. Previous researches mostly focus on seismic responses of rocking wall frame structures, while damage mode and reparability have not been investigated in detail. In this study, a novel infilled rocking wall frame (IRWF) structure is proposed. A half‐scaled IRWF model was designed according to Chinese seismic design code. The model was subjected to cyclic pushover testing up to structure drift ratio of 1/50 (amplitude 1/50), and its reparability was evaluated thereafter. Retrofit was implemented by wrapping steel plates and installing friction dampers. The retrofitted model was further loaded up to amplitude 1/30. The IRWF model showed excellent reparability and satisfactory seismic performance on deformation control, damage mode, hysteresis behavior, and beam‐to‐column joint rotation. After retrofitting, capacity of the model was improved by 11% with limited crack distribution. The model did not degrade until amplitude 1/30, due to shear failure in frame beams. The retrofit procedure was proved effective, and reparability of the IRWF model was demonstrated. Seismic resilience tends to be achieved in the proposed system.

Sublethal effects of imidacloprid on the fecundity, longevity, and enzyme activity of Sitobion avenae (Fabricius) and Rhopalosiphum padi (Linnaeus).

The aphid species Sitobion avenae and Rhopalosiphum padi are the most important pests in wheat growing regions of many countries. In this study, we investigated the sublethal effects of imidacloprid on fecundity, longevity, and enzyme activity in both aphid species by comparing 3-h exposure for one or three generations. Our results indicated that 3-h exposure to sublethal doses of imidacloprid for one generation had no discernible effect on the survival, fecundity, longevity, or enzyme activity levels of aphids. However, when pulse exposures to imidacloprid were sustained over three generations, both fecundity and longevity were significantly decreased in both S. avenae and R. padi. Interestingly, the fecundity of R. padi had almost recovered by the F5 generation, but its longevity was still deleteriously affected. These results indicated that R. padi laid eggs in shorter time lags and has a more fast resilience. The change in reproduction behavior may be a phenomenon of R. padi to compensate its early death. If this is stable for the next generation, it means that the next generation is more competitive than unexposed populations, which could be the reason underlying population outbreaks that occur after longer-term exposure to an insecticide. This laboratory-based study highlights the sublethal effects of imidacloprid on the longevity and fecundity of descendants and provides an empirical basis from which to consider management decisions for chemical control in the field.

Error resilience video coding parameters and mechanisms selection with End-to-End rate-distortion analysis at frame level

To improve the quality of video transmission, a fast error resilience coding method based on frame level rate-distortion analysis is proposed. To constrain the accumulated error propagation distortion and error concealment distortion simultaneously, reference frame selection and intra/inter mode decision are jointly used with redundant pictures. An adaptive multiple redundant picture (AMRP) coding mechanism is used for redundant picture coding with the adaptively estimated number of redundant pictures and encoding parameter for each specific redundant picture. The encoding parameters of different frames are adjusted based on the distortion propagation. We propose a statistical model for efficiently estimating the distortion and rate of the primary and the redundant picture. The total distortion and rate of the primary and the redundant picture are then formulated as a function of the quantization parameter, the temporal prediction distance, and the error resilient configuration. Lastly, the end-to-end rate-distortion optimized selection of the encoding parameters and coding structure is efficiently performed considering error propagation. Experimental results demonstrate that the proposed algorithm exhibits significant performance gains over the state-of-the-art error-resilient encoding methods.

OpenFlow-Based Segment Protection in Ethernet Networks

Metro and carrier-grade Ethernet networks, as well as industrial area networks and specific local area networks (LANs), have to guarantee fast resiliency upon network failure. However, the current OpenFlow architecture, originally designed for LANs, does not include effective mechanisms for fast resiliency. In this paper, the OpenFlow architecture is enhanced to support segment protection in Ethernet-based networks. Novel mechanisms have been specifically introduced to maintain working and backup flows at different priorities and to guarantee effective network resource utilization when the failed link is recovered. Emulation and experimental demonstration implementation results show that the proposed architecture avoids both the utilization of a full-state controller and the intervention of the controller upon failure, thus guaranteeing a recovery time only due to the failure detection time, i.e., a few tens of milliseconds within the considered scenario.

Mobility of sources and listeners: real-time support of multicast services

In today's Internet there is an increasing demand for group-based multimedia sessions, such as video/audio conferencing, IPTV, push media. Moreover, there is an increasing trend for mobile communications, with large network dynamic events, which require fast resilience to keep, as much as possible, sessions alive over time. In this sense, the bandwidth-constrained data transport scheme of IP multicast allows traffic optimization throughout the network. However, current IP multicast support over mobile communications is not efficient, mainly due to the IP addressing scheme and mobility. If multicast sources mobility is taken into account, then the performance of IP multicast is significantly degraded, due to the requirement for constantly changing the overall multicast tree. In this paper we propose a new solution for agent-based multicast in both sources and listeners mobile environments, called MUlticast TEleport (MUTE). MUTE considers the existence of anchor points in the network that provide proxy features, assuming the view of multicast data source inside the network, and establishing independence between listeners and sources movements. Moreover, we propose MUTE extension to efficiently support time-sensitive sessions, which consists in integrating IEEE 802.21 and QoS-aware abstracted transport approach, to allow media independent transport with fast resilience support. The evaluation of MUTE was carried out in NS-2, and the results show that it is able to provide both multicast sources and listeners mobility with decreased disruption time and increased network performance in heterogeneous systems.