Efficient Routing Protection Algorithm Based on Optimized Network Topology

Network failures are unavoidable and occur frequently. When the network fails, intra-domain routing protocols deploying on the Internet need to undergo a long convergence process. During this period, a large number of messages are discarded, which results in a decline in the user experience and severely affects the quality of service of Internet Service Providers (ISP). Therefore, improving the availability of intra-domain routing is a trending research question to be solved. Industry usually employs routing protection algorithms to improve intra-domain routing availability. However, existing routing protection schemes compute as many backup paths as possible to reduce message loss due to network failures, which increases the cost of the network and impedes the methods deployed in practice. To address the issues, this study proposes an efficient routing protection algorithm based on optimized network topology (ERPBONT). ERPBONT adopts the optimized network topology to calculate a backup path with the minimum path coincidence degree with the shortest path for all source purposes. Firstly, the backup path with the minimum path coincidence with the shortest path is described as an integer programming problem. Then the simulated annealing algorithm ERPBONT is used to find the optimal solution. Finally, the algorithm is tested on the simulated topology and the real topology. The experimental results show that ERPBONT effectively reduces the path coincidence between the shortest path and the backup path, and significantly improves the routing availability.     

Cu,N‐Codoped Carbon Nanodisks with Biomimic Stomata‐Like Interconnected Hierarchical Porous Topology as Efficient Electrocatalyst for Oxygen Reduction Reaction

Metal,N‐codoped carbon (M‐N‐C) nanostructures are promising electrocatalysts toward oxygen reduction reaction (ORR) or other gas‐involved energy electrocatalysis. Further creating pores into M‐N‐C nanostructures can increase their surface area, fully expose the active sites, and improve mass transfer and electrocatalytic efficiency. Nonetheless, it remains a challenge to fabricate M‐N‐C nanomaterials with both well‐defined morphology and hierarchical porous structures. Herein, high‐quality 2D Cu‐N‐C nanodisks (NDs) with biomimic stomata‐like interconnected hierarchical porous topology are synthesized via carbonization of Cu‐tetrapyridylporphyrin (TPyP)‐metal–organic frameworks (MOFs) precursors and followed by etching the carbonization product (Cu@Cu‐N‐C) along with re‐annealing treatment. Such hierarchical porous Cu‐N‐C NDs possess high specific surface area (293 m² g^?1) and more exposed Cu single‐atom sites, different from their counterparts (Cu@Cu‐N‐C) and pure N‐C control catalysts. Electrochemical tests in alkaline media reveal that they can efficiently catalyze ORR with a half‐wave potential of 0.85 V (vs reversible hydrogen electrode), comparable to Pt/C and outperforming Cu@Cu‐N‐C, N‐C, Cu‐TPyP‐MOFs, and most other reported M‐N‐C catalysts. Moreover, their stability and methanol‐tolerant capability exceed Pt/C. This work may shed some light on optimizing 2D M‐N‐C nanostructures through bio‐inspired pore structure engineering, and accelerate their applications in fuel cells, artificial photosynthesis, or other advanced technological fields.     

Non‐Volatile ReRAM Devices Based on Self‐Assembled Multilayers of Modified Graphene Oxide 2D Nanosheets

2D nanomaterials have been actively utilized in non‐volatile resistive switching random access memory (ReRAM) devices due to their high flexibility, 3D‐stacking capability, simple structure, transparency, easy fabrication, and low cost. Herein, it demonstrates re‐writable, bistable, transparent, and flexible solution‐processed crossbar ReRAM devices utilizing graphene oxide (GO) based multilayers as active dielectric layers. The devices employ single‐ or multi‐component‐based multilayers composed of positively charged GO (N‐GO(+) or NS‐GO(+)) with/without negatively charged GO(‐) using layer‐by‐layer assembly method, sandwiched between Al bottom and Au top electrodes. The device based on the multi‐component active layer Au/[N‐GO(+)/GO(‐)]_n/Al/PES shows higher ON/OFF ratio of ≈10⁵ with switching voltage of ?1.9 V and higher retention stability (≈10⁴ s), whereas the device based on single component (Au/[N‐GO(+)]_n/Al/PES) shows ≈10³ ON/OFF ratio at ±3.5 V switching voltage. The superior ReRAM properties of the multi‐component‐based device are attributed to a higher coating surface roughness. The Au/[N‐GO(+)/GO(–)]_n/Al/PES device prepared from lower GO concentration (0.01%) exhibits higher ON/OFF ratio (≈10⁹) at switching voltage of ±2.0 V. However, better stability is achieved by increasing the concentration from 0.01% to 0.05% of all GO‐based solutions. It is found that the devices containing MnO₂ in the dielectric layer do not improve the ReRAM performance.     

Diagnosis Modelling for Dependability Assessment of Fault‐Tolerant Systems Based on Stochastic Activity Networks

The growing demand for safety, reliability, availability and maintainability in modern technological systems has led these systems to become more and more complex. To improve their dependability, many features and subsystems are employed like the diagnosis system, control system, backup systems, and so on. These subsystems have all their own dynamic, reliability and performances and interact with each other in order to provide a dependable and fault‐tolerant system. This makes the dependability analysis and assessment very difficult. This paper proposes a method to completely model the diagnosis procedure in fault‐tolerant systems using stochastic activity networks. Combined with Monte Carlo simulation, this will allow the dependability assessment by including the diagnosis parameters and performances explicitly. Copyright © 2014 John Wiley & Sons, Ltd.     

Nanolattices of Switchable DNA‐Based Motors

Miniaturization is an important aspect of device fabrication. Despite the advancements of modern top‐down approaches, scaling‐down to the sub‐nanometer size is still a challenge. As an alternative, bottom‐up approaches, such as the use of DNA as an engineering material, are therefore emerging, allowing control of matter at the single‐molecule level. A DNA‐based self‐assembly method for the construction of switchable DNA devices is descrbied here based on G‐quadruplex moieties, which are patterned on quasi‐planar DNA arrays with nanoscale precision. The reversible switching of the devices is triggered by addition of DNA sequences (‘fuels’) and translated into linear extension/contractile movements. The conformational change of the devices was visualized by atomic force microscopy and FRET spectroscopy. Steady state fluorescence spectroscopy indicated that scaffolding of the G4 motors to either individual tiles or extended superlattices had no significant impact on the switching and optical performance of the system. However, time‐resolved spectroscopy revealed that ordering in the microstructural environment enhances the fraction of molecules subject to FRET. Altogether, our study confirms that DNA superstructures are well‐suited scaffolds for accommodation of mechanically switchable units and thus opens the door to the development of more sophisticated nanomechanical devices.     

Intranasal Nanovaccine Confers Homo‐ and Hetero‐Subtypic Influenza Protection

Cross‐protective and non‐invasively administered vaccines are attractive and highly desired for the control of influenza. Self‐assembling nanotechnology provides an opportunity for the development of vaccines with superior performance. In this study, an intranasal nanovaccine is developed targeting the conserved ectodomain of influenza matrix protein 2(M2e). 3‐sequential repeats of M2e (3M2e) is presented on the self‐assembling recombinant human heavy chain ferritin (rHF) cage to form the 3M2e‐rHF nanoparticle. Intranasal vaccination with 3M2e‐rHF nanoparticles in the absence of an adjuvant induces robust immune responses, including high titers of sera M2e‐specific IgG antibodies, T‐cell immune responses, and mucosal secretory‐IgA antibodies in mice. The 3M2e‐rHF nanoparticles also confer complete protection against a lethal infection of homo‐subtypic H1N1 and hetero‐subtypic H9N2 virus. An analysis of the mechanism of protection underlying the intranasal immunization with the 3M2e‐rHF nanoparticle indicates that M2e‐specific mucosal secretory‐IgA and T‐cell immune responses may play critical roles in the prevention of infection. The results suggest that the 3M2e‐rHF nanoparticle is a promising, needle‐free, intranasally administered, cross‐protective influenza vaccine. The use of self‐assembling nanovaccines could be an ideal strategy for developing vaccines with characteristics such as high immunogenicity, cross‐protection, and convenient administration, as well as being economical and suitable for large‐scale production.     

Water‐Stable Chemical‐Protective Textiles via Euhedral Surface‐Oriented 2D Cu–TCPP Metal‐Organic Frameworks

Abatement of chemical hazards using adsorptive metal‐organic frameworks (MOFs) attracts substantial attention, but material stability and crystal integration into functional systems remain key challenges. Herein, water‐stable, polymer fiber surface–oriented M–TCPP [M = Cu, Zn, and Co; H₂TCPP = 5,10,15,20‐tetrakis(4‐carboxyphenyl)porphyrin] 2D MOF crystals are fabricated using a facile hydroxy double salt (HDS) solid‐source conversion strategy. For the first time, Cu–TCPP is formed from a solid source and confirmed to be highly adsorptive for NH₃ and 2‐chloroethyl ethyl sulfide (CEES), a blistering agent simulant, in humid (80% relative humidity (RH)) conditions. Moreover, the solid HDS source is found as a unique new approach to control MOF thin‐film crystal orientation, thereby facilitating radially arranged MOF crystals on fibers. On a per unit mass of MOF basis in humid conditions, the MOF/fiber composite enhances NH₃ adsorptive capacity by a factor of 3 compared to conventionally prepared MOF powders. The synthesis route extends to other MOF/fiber composite systems, therefore providing a new route for chemically protective materials.     

Approximate Reliability and Availability Models for High Availability and Fault‐tolerant Systems with Repair

Systems designed for high availability and fault tolerance are often configured as a series combination of redundant subsystems. When a unit of a subsystem fails, the system remains operational while the failed unit is repaired; however, if too many units in a subsystem fail concurrently, the system fails. Under conditions usually met in practical situations, we show that the reliability and availability of such systems can be accurately modeled by representing each redundant subsystem with a constant, ‘effective’ failure rate equal to the inverse of the subsystem mean‐time‐to‐failure (MTTF). The approximation model is surprisingly accurate, with an error on the order of the square of the ratio mean‐time‐to‐repair to mean‐time‐to‐failure (MTTR/MTTF), and it has wide applicability for commercial, high‐availability and fault‐tolerant computer systems. The effective subsystem failure rates can be used to: (1) evaluate the system and subsystem reliability and availability; (2) estimate the system MTTF; and (3) provide a basis for the iterative analysis of large complex systems. Some observations from renewal theory suggest that the approximate models can be used even when the unit failure rates are not constant and when the redundant units are not homogeneous. Copyright © 2004 John Wiley & Sons, Ltd.     

Wirkungsweise von Lotwerkstoffen beim M‐Effekt

On the mechanism of solders during the M‐effect Slaggish switching‐off behaviour of HBC‐fusions (M‐effect) is ensured by a solder droplet on the copper fusion conductor. First the function of currently used toxic SnCd20 solder was investigated by melting, switching off and annealing tests. With these results the mechanism of the “M‐effect” was described and further tests were made with alternative alloys tin‐bismuth, tin‐indium and ternary alloys tin‐bismuth‐copper and tin‐indium‐copper. The ternary system tin‐bismuth‐copper was found to give best results and showed the same time‐temperature‐dissolution‐behaviour during the M‐effect as the SnCd20 solder. Function of different solders and necessary properties are discussed.     

Precise Two‐Photon Photodynamic Therapy using an Efficient Photosensitizer with Aggregation‐Induced Emission Characteristics

Two‐photon photodynamic therapy (PDT) is able to offer precise 3D manipulation of treatment volumes, providing a target level that is unattainable with current therapeutic techniques. The advancement of this technique is greatly hampered by the availability of photosensitizers with large two‐photon absorption (TPA) cross section, high reactive‐oxygen‐species (ROS) generation efficiency, and bright two‐photon fluorescence. Here, an effective photosensitizer with aggregation‐induced emission (AIE) characteristics is synthesized, characterized, and encapsulated into an amphiphilic block copolymer to form organic dots for two‐photon PDT applications. The AIE dots possess large TPA cross section, high ROS generation efficiency, and excellent photostability and biocompatibility, which overcomes the limitations of many conventional two‐photon photosensitizers. Outstanding therapeutic performance of the AIE dots in two‐photon PDT is demonstrated using in vitro cancer cell ablation and in vivo brain‐blood‐vessel closure as examples. This shows therapy precision up to 5 µm under two‐photon excitation.     

A Joint Reliability and Imperfect Opportunistic Maintenance Optimization for a Multi‐State Weighted k‐out‐of‐n System Considering Economic Dependence and Periodic Inspection

This paper formulates a model to simultaneously optimize the redundancy and imperfect opportunistic maintenance of a multi‐state weighted k‐out‐of‐n system. Different from existing approaches that consider binary or multi‐state elements, our approach considers modular redundancy in which each module/subsystem is composed of several multi‐state components in series. The status of each component is considered to degrade with use. Therefore, a new condition‐based opportunistic maintenance approach using three different thresholds for a component health state is developed. The objective is to determine 1) the minimal‐cost of k‐out‐of‐n system structure, 2) optimal imperfect opportunistic maintenance strategy, 3) optimal maintenance capacity, and 4) optimal inspection interval subject to an availability constraint. System availability is defined as the ability to satisfy consumer demand. Based on the three‐phase approach, a simulation procedure is used to evaluate the expected multi‐state system availability and life cycle costs. Also, a multi‐seed Tabu search heuristic algorithm with a proper neighborhood generation mechanism is proposed to solve the formulated problem. An application to the optimal design of a wind farm is provided to illustrate the proposed approach. Sensitivity analysis is conducted to discuss the influence of the different parameters of the simulation model. Copyright © 2017 John Wiley & Sons, Ltd.     

Effect of microstructure of simulated heat‐affected zone on low‐ to high‐cycle fatigue properties of low‐carbon steels

To clarify the effect of microstructural changes on the fatigue property of the weld heat‐affected zone (HAZ), low‐ to high‐cycle fatigue tests were conducted on 16 types of simulated HAZ specimens that had been prepared using thermal processes. The results showed the fatigue S‐N curves of the HAZ to be widely scattered as a function of strength level. These fatigue data were divided into two groups: coarse grain (CG) and fine grain (FG) HAZ, when strain amplitude was used to represent S‐N curves. The fatigue data for the CGHAZ group showed a relatively short fatigue life. Based on surface observations, the initiated fatigue crack size of CGHAZ was larger than that of FGHAZ as a function of microstructural unit size. Hence, fatigue crack growth life, which is almost the same as total fatigue life of CGHAZ, decreased.     

An over‐current protection module for telephone network line cards—an analysis of electro‐thermal properties

In this paper the results of a finite‐element analysis of the electro‐thermal behaviour of an over‐current protection thick‐film hybrid module are presented. The module was designed for protecting the line card of a telephone network against an abnormal surge of current, resulting from accidental shorts between adjacent power feed lines. The switching time of the device is crucial to its effectiveness as a protective element. A transient finite‐element thermal analysis was performed in order to predict the dynamic temperature states at the critical points of the circuit design and to evaluate the influence on the switching characteristics. A comparison between simulated and practical results is given. Copyright © 2002 John Wiley & Sons, Ltd.     

Erosions‐Korrosions‐Untersuchungen an gradierten Multilayer‐Chromkarbidschichten

Erosion corrosion of graded chromium carbide coatings in multi layer structure So far PVD‐ and PECVD‐Layers have proved their value as wear protection mainly on cutting tools for machining. Depending on the composition of the layers not only a reduction in wear but also a reduction in friction is possible, e.g. by integration of hydrogen containing carbon. Furthermore such carbon containing layers use to be electrochemically inert. Thus they don’t corrode in aqueous media. Because they do also have a very dense structure, an application as corrosion protection seems to be promising. For the intended investigations under service‐like erosiv‐corrosiv loading a new testing rig was developed and constructed. The erosiv‐corrosiv loading was achieved by exposure of coated specimen to a flowing medium, that contains abrasive corund‐particles. Thus the erosion‐corrosion‐behaviour of new graded Multilayer‐Chromiumcarbide‐Coatings should be investigated. The aim was to identify the mechanisms of deterioration to promote a further developement of these layers. In addition the potential of PVD/PECVD‐coated low‐alloy steel to be in‐service under such conditions should be evaluated. For comparison an up‐to‐date industrial DLC‐coating and a high‐alloy duplex‐steel were also investigated. As a result of the conducted investigations an application of PVD‐/PECVD‐coated low‐alloy steel under erosive‐corrosive conditions with impingement wear could not yet be recommended. However the graded Multilayer‐Chromiumcarbide‐Coatings have the potential for a good erosion‐corrosion‐protection, if erosion promoting flaws are avoided. Because hard PVD‐ and PECVD‐coatings are relative brittle, a loading with hard particles, which hit the surface under a high angle, is very tough. Hence the question is, if the investigated layers possibly have a better wear behaviour under more abrasive loading in a more tangential flowing medium, which is also typical for in‐service‐conditions. This is intended to be investigated in future tests.     

Reliability modeling of multi‐state degraded repairable systems and its applications to automotive systems

In this paper, we presented a continuous‐time Markov process‐based model for evaluating time‐dependent reliability indices of multi‐state degraded systems, particularly for some automotive subsystems and components subject to minimal repairs and negative repair effects. The minimal repair policy, which restores the system back to an “as bad as old” functioning state just before failure, is widely used for automotive systems repair because of its low cost of maintenance. The current study distinguishes with others that the negative repair effects, such as unpredictable human error during repair work and negative effects caused by propagated failures, are considered in the model. The negative repair effects may transfer the system to a degraded operational state that is worse than before due to an imperfect repair. Additionally, a special condition that a system under repair may be directly transferred to a complete failure state is also considered. Using the continuous‐time Markov process approach, we obtained the general solutions to the time‐dependent probabilities of each system state. Moreover, we also provided the expressions for several reliability measures include availability, unavailability, reliability, mean life time, and mean time to first failure. An illustrative numerical example of reliability assessment of an electric car battery system is provided. Finally, we use the proposed multi‐state system model to model a vehicle sub‐frame fatigue degradation process. The proposed model can be applied for many practical systems, especially for the systems that are designed with finite service life.     

A simplified life cycle assessment of re‐usable and single‐use bulk transit packaging

A streamlined (simplified) life cycle assessment of a conventional wooden pallet and an all‐weather, washable, re‐usable and fully recyclable plastic bulk transit packaging system used to transport empty yoghurt pottles, has been conducted using surrogate/proxy data from the Environmental Priorities Strategy (EPS) 2000 Default Method. This paper accounts for the life cycle inventory for each material used in the two transit packaging systems and their associated fabrication processes. The life cycle assessment was simplified by ignoring common factors such as the common nylon strap of both packaging systems, the common in‐house transportation, and the manufacture and maintenance of capital equipment. The system boundaries and assumptions made are also discussed. The functional unit adopted was the Environmental Load Units (ELU) of the EPS 2000 Default Method. The grand overall ELU for the wooden pallet and plastic packaging system are computed by considering the weight of the material, the volume of inventory and the distance travelled. The ELU of the wooden pallet was 18.455, while that for the plastic packaging was 4.574 at a 96.5% level of certainty. In the case of the wooden pallet, truck transport, the corrugated cardboard boxes and the LDPE liner and shrinkwrap impacted the environment most, while for the plastic packaging system truck transport and the LDPE liner were significant. The plastic packaging has a lower environmental impact than the wooden pallet for various reasons. It is lighter in weight, has more re‐usable parts and can transport more yoghurt pottles per trip. It has a long service life and is virtually fully recyclable. Copyright © 2004 John Wiley & Sons, Ltd.     

A frequency‐domain formulation of MCE method for multi‐axial random loadings

Many multi‐axial fatigue limit criteria are formalized as a linear combination of a shear stress amplitude and a normal stress. To identify the shear stress amplitude, appropriate conventional definitions, as the minimum circumscribed circle (MCC) or ellipse (MCE) proposals, are in use. Despite computational improvements, deterministic algorithms implementing the MCC/MCE methods are exceptionally time‐demanding when applied to “coiled” random loading paths resulting from in‐service multi‐axial loadings and they may also provide insufficiently robust and reliable results. It would be then preferable to characterize multi‐axial random loadings by statistical re‐formulations of the deterministic MCC/MCE methods. Following an early work of Pitoiset et al., this paper presents a statistical re‐formulation for the MCE method. Numerical simulations are used to compare both statistical re‐formulations with their deterministic counterparts. The observed general good trend, with some better performance of the statistical approach, confirms the validity, reliability and robustness of the proposed formulation.     

A Unit‐Cell Approach of Finite Element Analysis for Transverse Impact Damage of 3‐D Biaxial Spacer Weft‐Knitted Composite

Abstract: This paper evaluates the transverse impact damage of a 3‐D biaxial spacer weft‐knitted composite using experimental results and complimentary finite element analysis. The load–displacement curves and damage morphologies during impact loading were obtained to analyse energy absorption and impact damage mechanisms of the knitted composite. A unit‐cell model based on the microstructure of the 3‐D knitted composite was established to calculate the deformation and damage evolution when the composite is impacted by a hemisphere‐ended steel rod. An elastoplastic constitutive equation is incorporated into the unit‐cell model and the critical damage area failure theory developed by Hahn and Tsai has been implemented as a user‐defined material law (VUMAT) for commercial available finite element code ABAQUS/Explicit. The load–displacement curves, impact damages and impact energy absorption obtained from ABAQUS/Explicit are compared with those FROM experiments. The good agreement of the comparisons supports the validity of the unit‐cell model and user‐defined subroutine VUMAT. The unit‐cell model can also be extended to evaluate the impact crashworthiness of engineering structures made out of the 3‐D knitted composites.     

Polymer‐Based Stimuli‐Responsive Recyclable Catalytic Systems for Organic Synthesis

The introduction of stimuli‐responsive polymers into the study of organic catalysis leads to the generation of a new kind of polymer‐based stimuli‐responsive recyclable catalytic system. Owing to their reversible switching properties in response to external stimuli, these systems are capable of improving the mass transports of reactants/products in aqueous solution, modulating the chemical reaction rates, and switching the catalytic process on and off. Furthermore, their stimuli‐responsive properties facilitate the separation and recovery of the active catalysts from the reaction mixtures. As a fascinating approach of the controllable catalysis, these stimuli‐responsive catalytic systems including thermoresponsive, pH‐responsive, chemo‐mechano‐chemical, ionic strength‐responsive, and dual‐responsive, are reviewed in terms of their nanoreactors and mechanisms.     

Monitoring of user‐generated reviews via a sequential reverse joint sentiment‐topic model

User‐generated reviews can serve as an efficient tool for evaluating the customer‐perceived quality of online products and services. This article proposes a joint control chart for monitoring the quantitative evolution of document‐level topics and sentiments in online customer reviews. A sequential model is constructed to convert the temporally correlated document collections to topic and sentiment distributions, which are subsequently used to monitor the topics that users are concerned about and the topic‐specific opinions in an ongoing product and service process. Simulation studies on various data scenarios demonstrate the superior performance of the proposed control chart in terms of both detecting shifts and identifying truly out‐of‐control terms.