Dozens of two-factor authentication schemes have been proposed to secure real-time data access in industrial wireless sensor networks (WSNs). However, more often than not, the protocol designers ...advocate the merits of their scheme, but do not reveal (or unconsciously ignoring) the facets on which their scheme performs poorly. Such lack of an objective, comprehensive measurement leads to the unsatisfactory "break-fix-break-fix" cycle in this research area. In this paper, we make an attempt toward breaking this undesirable cycle by proposing a systematical evaluation framework for schemes to be assessed objectively, revisiting two foremost schemes proposed by Wu et al. (2017) and Srinivas et al. (2017) to reveal the challenges and difficulties in designing a sound scheme, and conducting a measurement of 44 representative schemes under our evaluation framework, thereby providing the missing evaluation for two-factor schemes in industrial WSNs. This work would help increase awareness of current measurement issues and improve the scientific process in our field.
Abstract
The low Coulombic efficiency during cycling hinders the application of Cobalt-free lithium-rich materials in lithium-ion batteries. Here we demonstrated that the dissolution of iron, rather ...than traditionally acknowledged manganese, is mainly responsible for the low Coulombic efficiency of the iron-substituted cobalt-free lithium-rich material. Besides, we presented an approach to inhibit the dissolution of transition metal ions by using concentrated electrolytes. We found that the cathode electrolyte interphase (CEI) layer formed in the concentrated electrolyte is a uniform and robust LiF-rich CEI, which is a sharp contrast with the uneven and fragile organic-rich CEI formed in the dilute electrolyte. The LiF-rich CEI not only effectively inhibits the dissolution of TMs but also stabilizes the cathode structure. The Coulombic efficiency, cycling stability, rate performance, and safety of the Fe-substituted cobalt-free lithium-rich cathode material in the concentrated electrolyte have been improved tremendously.
Self‐healing is a natural phenomenon whereby living organisms respond to damage. Recently, considerable research efforts have been invested in self‐healing cementitious materials that are capable of ...restoring structural integrity and mechanical properties after being damaged. Inspired by nature, a variety of creative approaches are explored here based on the intrinsic or extrinsic healing mechanism. Research on new intrinsic self‐healing cementitious materials with biomimetic features is on the forefront of material science, which provides a promising way to construct resilient and sustainable concrete infrastructures. Here, the current advances in the development of the intrinsic healing cementitious materials are described, and a new definition of intrinsic self‐healing discussed. The methods to assess the efficiency of different healing mechanisms are briefly summarized. The critical insights are emphasized to guide the future research on the development of new self‐healing cementitious materials.
Recent advances in intrinsic self‐healing cementitious materials that favor high compatibility and chemical interactions with the cementitious matrix according to its essential healing mechanism are summarized, and the methods to assess the efficiency briefly discussed. The critical insights on this promising research field are provided to guide the future development of self‐healing of cementitious materials.
Fe
3
O
4
/P(GMA-DVB)/PAMAM/Au microspheres are fabricated to research the catalytic performances to 4-nitrophenol. In the preparation process, Fe
3
O
4
microspheres act as magnetic cores, PAMAM ...dendrimers growing up on the surface of P(GMA-DVB) polymer work as carriers, and Au nanoparticles serve as catalytic materials. The stability of the prepared microspheres is evaluated by successively catalytic experiments to measure the conversion of 4-nitrophenol, and catalytic efficiency can still maintain up to 78.7% after ten cycles. Moreover, the effects of major factors including the concentration of the prepared microspheres and the temperature of reaction system on the conversion of 4-nitrophenol are also investigated in detail. The manuscript reveals that 4-nitrophenol can be almost converted to 4-aminophenol within 7 min at 45 °C in the case of using 1.0 g/L Fe
3
O
4
/P(GMA-DVB)/PAMAM/Au microspheres. Such excellent catalytic properties are ascribed to the optimum structure of the prepared microspheres, which favors the sufficient contact between Au nanoparticles and 4-nitrophenol. The results and strategies exhibited here provide insight into the preparation of sophisticated structures of catalysts to treat wastewater.
Self-healing of cracks in cementitious composites is of great significance to improve the serviceability of concrete structures. In this study, poly urea–formaldehyde (PUF) microcapsules enclosing ...epoxy resins were synthesized. The damage- and healing process of cement paste incorporating microcapsules was in situ detected by acoustic emission (AE) technique, in which passive AE and active AE were combined to provide complementary information about the damage and crack formation. The two representative AE signals, i.e., matrix cracking and debonding of the interface, were used as calibration for further AE post-processing analysis. The effects of the concentration of microcapsules and the level of pre-damage were investigated. The results revealed the distinguished cracking mechanisms according to the differentiated feature of the signals in terms of the temporal and spectral AE descriptors. The plot of average frequency (AF) versus RA index (rise time/amplitude) confirms that the cracking modes contribute to the characteristic spectrum.
Autonomous crack healing of cementitious composite, a construction material that is susceptible to cracking, is of great significance to improve the serviceability and to prolong the longevity of ...concrete structures. In this study, the St-DVB microcapsules enclosing epoxy resins as the adhesive agent were embedded in cement paste to achieve self-healing capability. The self-healing efficiency was firstly assessed by mechanical restoration of the damaging specimens after being matured. The flexural and compressive configurations were both used to stimulate the localized and distributed cracks respectively. The effects of some factors, including the content of microcapsules, the curing conditions and the degree of damage on the healing efficiency were investigated. Water absorption was innovatively proposed to monitor and characterize the evolution of crack networks during the healing process. The healing cracks were observed by SEM-EDS following. The results demonstrated that the capsule-containing cement paste can achieve the various mechanical restorations depending on the curing condition and the degree of damage. But the voids generated by the surfactants compromised the strength. Though no noticeable improved stiffness obtained, the increasing fracture energy was seen particularly for the specimen acquiring 60% pre-damage. The sorptivity and amount of water decreased with cracks healing by the adhesive, which contributed to cut off and block ingress of water. The micrographs by SEM-EDS also validated that the cracks were bridged by the hardened epoxy as the dominated elements of C and O accounted for 95% by mass in the nearby cracks.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
•3D nonlinear simulation of the seismic behavior of site-city interaction.•Ground buildings generally decreases the station’s seismic responses.•Buildings’ effect on tunnels is big at areas slightly ...above/below horizontal axis.•The presence of either ground buildings or underground structures affect PGA.•The site-city interaction system’s response in frequency domain is complex.
Underground structures often pass beneath high-rise buildings or are located close to them in megacities. Given complex site-city interactions, conventional earthquake engineering practices may leave megacities in seismically prone areas in potential danger. Rather than focusing purely on the interaction between soil and either surface structures or underground structures, this study aims to explore the earthquake-induced hazard of a dense urban area with an entire subway station, two long subway tunnels and 36 fully modeled high-rise piled frame buildings. The study is conducted through the 3D fully coupled dynamic analysis in both the time and frequency domains, emphasizing the influence of aboveground buildings on underground structures. The results reveal that the existence of aboveground buildings generally decreases the station’s response and can either increase or decrease the subway tunnel’s responses. The presence of either aboveground structures or underground structures affects the wavefield and in turn the responses of adjacent structures, highlighting the importance of considering soil-city interactions. The station is most dangerous at the columns’ bottoms. The existence of subway stations and tunnels increases the nearby peak ground accelerations.
•Fluorescence intensity and color of apt-Cu@Au NCs served as signal reporters of Hg2+.•The aptasensor shows high sensitivity for Hg2+ with detection limit of 4.92 nM.•A portable colorimetric ...microsystem was proposed for visual detection of Hg2+.•The aptasensor exhibited considerable potential for Hg2+ detection in Porphyra.
A novel aptamer-modified Copper @ Gold nanoclusters (apt-Cu@Au NCs) based ratiometric fluorescent probe was developed for mercury ions (Hg2+) determination in Porphyra. The apt-Cu@Au NCs were well dispersed in solution without Hg2+ but combined together for the formation of thymidine–Hg–thymidine structure with the addition of Hg2+, which further caused the changes in their fluorescence intensities owing to fluorescence resonance energy transfer. Along with that, the changes in fluorescent colors are visible to the naked eye. Accordingly, Hg2+ were determined ranging from 0.1 to 9.0 μM by fluorescence analysis with the detection limit of 4.92 nM. Moreover, a homemade device utilizing smartphone and microfluidic chip was designed for colorimetric determination of Hg2+ ranging from 0.5 to 7.0 μM with good portability and usefulness. The proposed methods were used for Hg2+ detection in Porphyra with the recoveries of 101.83–114.00%, suggesting the considerable potential for evaluating Hg2+ levels in aquatic products.
One-dimensional (1D) microwave absorbing materials (MAMs) can induce self-assembly of graphene into aerogels, which provides ideas for the preparation of new MAMs. In here, 3D flower-like ...Fe3O4@SiO2@MnO2@reduced graphene oxide (RGO) (FSMG) composite aerogels have been fabricated via hydrothermal method, in which 1D Fe3O4@SiO2 (FS) nanochains and two-dimensional (2D) MnO2 sheets form a nano-scale core-shell structure on the surface of the RGO nanosheets. The unique microstructure of aerogels greatly enhances the microwave absorption capability. Particularly, the addition of RGO regulates the complex permittivity and improves the impedance matching of 1D Fe3O4@SiO2@MnO2 (FSM) nanochains. Results demonstrate that the well-designed 3D conductive networks with significant oxygen vacancy defects powerfully favor the electromagnetic wave (EMW) absorption. The as-prepared FSMG composite aerogels show efficient microwave absorption (MA) properties with the maximum effective absorption bandwidth (EAB) of 4.26 GHz (7.13–11.39 GHz) at the corresponding coating thickness of 3.2 mm, accompanied by the minimum reflection loss (RLmin) of about −55.01 dB. This work indicates that the FSMG composite aerogels are excellent absorbers with wide bandwidth, strong absorption, thin thickness and light weight, which can become a hopeful candidate in the field of MA.
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•The novel lightweight composite aerogels of Fe3O4@SiO2@MnO2@RGO were fabricated successfully.•One-dimensional flower-like Fe3O4@SiO2@MnO2 nanochains were uniformly anchored onto the surface of the RGO nanosheets.•The microwave absorption mechanism of Fe3O4@SiO2@MnO2@RGO composite aerogels was elucidated in depth.•The composite aerogels exhibit strong absorption (RLmin = −55.01 dB at 7.78 GHz) and broad bandwidth (7.13–11.39 GHz).
Route guidance strategies are an important part of advanced traveler information systems, which are a subsystem of intelligent transportation systems (ITSs). In previous research, many scholars have ...proposed a variety of route guidance strategies to guide vehicles in order to relieve traffic congestion, but few scholars have considered a strategy to control transportation infrastructure. In this paper, to cope with tidal traffic, we propose a dynamic lane reversal strategy (DLRS) based on the density of congestion clusters over the total road region. When the density reaches 0.37, the reversible lane converts to the opposite direction. When the density falls off to below 0.22, the reversible lane returns back to the conventional direction. The simulation results show that the DLRS has better adaptability for coping with the fluctuation in tidal traffic.
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