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Compared with acceleration-based modal analysis, displacement can provide a more reliable and robust identification result for output-only modal analysis of long-span bridges. However, the estimated displacements from acceleration records are frequently unavailable due to unrealistic drifts. Aiming at obtaining more accurate and stable results for determining the modal parameters, this study develops a multi-rate weighted data fusion approach for estimating displacement responses in dynamic monitoring of structures based on global navigation satellite system (GNSS) and acceleration measurements. The approach initially derives the local estimations from displacement and acceleration sensors via a Kalman filter algorithm with colored measurement noise, and later uses a weighted fusion criterion of scalar linear minimum variance to fuse the results of local estimations. Then, structural modal pamameters are identified by employing data-driven stochastic subspace identification (SSI) algorithm. The proposed approach is validated in a four degree-of-freedom numerical model and then applied to a long-span bridge in engineering practice. The results illustrate that the proposed approach can reduce the error of GNSS-obtained displacement and expand recognizable frequency range by introducing dynamic displacement component from acceleration measurement. [ABSTRACT FROM AUTHOR]

In this study, we successfully synthesized N-phenylmaleimide (NPMI) and applied it to wool fabrics to obtain robust antimicrobial properties. First, tris(2-carboxyethyl) phosphine (TCEP) was utilized as a reducing agent to produce thiol-active groups on wool fibers. These thiol groups were then reacted with the C=C group of NPMI via thiol-ene click chemistry. The morphology and structure of the finished NPMI composite wool fabric were characterized using FT-IR spectroscopy, Raman spectroscopy and scanning electron microscopy (SEM). The composite wool fabrics exhibited durable antibacterial properties against both S. aureus and E. coli and the antimicrobial rates of both E. coli and S. aureus were around 99% after one standard washing cycle, with only a slight decrease of 95% after ten standard washing cycles, respectively. In addition, the composite wool fabric exhibited good anti-felting performance and maintained its original excellent breathability and moisture permeability. The present work provides a facile and sustainable strategy for constructing durable antimicrobial wool fabrics without losing their original properties. [ABSTRACT FROM AUTHOR]

Proton exchange membrane fuel cell (PEMFC) powered automobiles have been recognized to be the ultimate solution to replace traditional fuel automobiles because of their advantages of PEMFCs such as no pollution, low temperature start-up, high energy density, and low noise. As one of the core components, the bipolar plates (BPs) play an important role in the PEMFC stack. Traditional graphite BPs and composite BPs have been criticized for their shortcomings such as low strength, high brittleness, and high processing cost. In contrast, stainless steel BPs (SSBPs) have recently attracted much attention of domestic and foreign researchers because of their excellent comprehensive performance, low cost, and diverse options for automobile applications. However, the SSBPs are prone to corrosion and passivation in the PEMFC working environment, which lead to reduced output power or premature failure. This review is aimed to summarize the corrosion and passivation mechanisms, characterizations and evaluation, and the surface modification technologies in the current SSBPs research. The non-coating and coating technical routes of SSBPs are demonstrated, such as substrate component regulation, thermal nitriding, electroplating, ion plating, chemical vapor deposition, and physical vapor deposition, etc. Alternative coating materials for SSBPs are metal coatings, metal nitride coatings, conductive polymer coatings, and polymer/carbon coatings, etc. Both the surface modification technologies can solve the corrosion resistance problem of stainless steel without affecting the contact resistance, however still facing restraints such as long-time stability, feasibility of low-cost, and mass production process. This paper is believed to enrich the knowledge of high-performance and long-life BPs applied for PEMFC automobiles. [ABSTRACT FROM AUTHOR]

Energy storage and conversion via a hydrogen chain is a recognized vision of future energy systems based on renewables and, therefore, a key to bridging the technological gap toward a net-zero CO2 emission society. This paper reviews the hydrogen technological chain in the framework of renewables, including water electrolysis, hydrogen storage, and fuel cell technologies. Water electrolysis is an energy conversion technology that can be scalable in megawatts and operational in a dynamic mode to match the intermittent generation of renewable power. Material concerns include a robust diaphragm for alkaline cells, catalysts and construction materials for proton exchange membrane (PEM) cells, and validation of the long-term durability for solid oxide cells. Hydrogen storage via compressed gas up to 70 MPa is optional for automobile applications. Fuel cells favor hydrogen fuel because of its superfast electrode kinetics. PEM fuel cells and solid oxide fuel cells are dominating technologies for automobile and stationary applications, respectively. Both technologies are at the threshold of their commercial markets with verified technical readiness and environmental merits; however, they still face restraints such as unavailable hydrogen fueling infrastructure, long-term durability, and costs to compete with the analog power technologies already on the market. [ABSTRACT FROM AUTHOR]

Over the years, graphene oxide (GO) with unique permeability and selectivity has been extensively researched for hydrophilic enhancement modification, especially as the separation layer of oil–water separation composite membranes. However, the poor stability caused by hydration of GO, and the low water flux caused by the lamellar compaction limit its application. In this study, a surface modification strategy based on metal polyphenol coordination was proposed to address these problems by co-deposition of tannic acid-graphene oxide (TA-GO) and TiO2 on electrospun polyvinylidene fluoride (PVDF) membrane. TiO2 was inserted into GO layers to expand the interlayer spacing and prevent membrane compaction. Moreover, the interlayer force was enhanced by TA and Fe3+ through covalent bonds, cation-π, and coordination bond. The results demonstrated that the underwater oil contact angle of resultant composite membrane reached 152.5°. In addition, it has a high flux (243.11 L/h·m2·bar) and oil (> 98%)/salt (> 47%) rejection, which can be maintained even after ultrasonic treatment for 30 min. This work proposed a practical and environmental approach to construct a steady GO-modified hydrophilic membrane. [ABSTRACT FROM AUTHOR]

GPS-dependent localization, tracking and navigation applications have a significant impact on the modern aviation industry. However, the lack of encryption and authentication makes GPS vulnerable for spoofing attacks with the purpose of hijacking aircrafts or threatening air safety. In this paper, we propose GPS-Probe, a GPS spoofing detection algorithm which leverages the air traffic control (ATC) messages periodically broadcasted by aircrafts. By exploiting the received signal strength indicator (RSSI) and the timestamps at server (TSS) of the ATC messages monitored by multiple ground sensors, GPS-Probe constructs a machine learning enabled framework which can estimate the real position of the target aircraft and then detect whether GPS is spoofed or not. Unlike existing techniques, GPS-Probe neither requires any updates of the GPS infrastructure nor of the GPS receivers. It also releases the requirement on the time synchronization of the ground sensors distributed around the world. We further present GPS-Probe-Plus by incorporating a flight height estimation module and a calibration method for RSSI and TSS values, which performs better on both target localization and spoofing detection than GPS-Probe. Using the real-world ATC data crowdsourced by OpenSky Network, our experiment results show that GPS-Probe (resp. GPS-Probe-Plus) can achieve an average detection accuracy and precision, of 81.7% (resp. 86.8%) and 85.3% (resp. 91.2%), respectively, significantly outperforming the state-of-the-arts. [ABSTRACT FROM AUTHOR]

As the core of a blockchain system, the consensus mechanism not only helps to maintain the consistency of node data, but also gets involved in the issuance of tokens and prevention of attacks. Since the first blockchain system was born, it has been continuously improved with the development of blockchain technology and evolved into multiple new branches. Starting with the basic introduction of consensus and the classic Byzantine Generals Problem in distributed computing area, this survey utilizes a thorough classification to explain current consensus protocols in the blockchain system, presents the characteristics of mainstream protocols (PoW, PoS, DPoS, PBFT, etc.) and analyzes the strengths and weaknesses of them. Then we evaluate the performance qualitatively and quantitatively. In the end, we highlight several research directions for developing more practical consensus protocols for the future. [ABSTRACT FROM AUTHOR]

Internet of connected vehicles (IoV) are expected to enable intelligent traffic management, intelligent dynamic information services, intelligent vehicle control, etc. However, vehicles' data privacy is argued to be a major barrier toward the application and development of IoV, thus causing a wide range of attentions. Local differential privacy (LDP) is the relaxed version of the privacy standard, differential privacy, and it can protect users' data privacy against the untrusted third party in the worst adversarial setting. Therefore, LDP is potential to protect vehicles' data privacy in the practical scenario, IoV, although vehicles exhibit unique features, e.g., high mobility, short connection times, etc. To this end, in this paper, we first give an overview of the existing LDP techniques and present the thorough comparisons of these work in terms of advantages, disadvantages, and computation cost, in order to get the readers well acquainted with LDP. Thereafter, we investigate the potential applications of LDP in securing IoV in detail. Last, we direct several future research directions of LDP in IoV, to bridge the gaps between LDP researches and the privacy preservation in IoV. The originality of this survey is that it is the first work to summarize and compare the existing LDP research work and that it also does an pioneering work toward the in-depth analysis of the potential applications of LDP in privacy preservation in IoV. [ABSTRACT FROM AUTHOR]

Chronic copper exposure impaired spermatogenesis in adult male mice. The aim of this study was to determine whether chronic copper exposure can induce apoptosis of testicular cell and hypospermatogenesis via disturbing testosterone synthesis in adult male mice. In the present study, sixty CD-1 male mice were randomly divided into four groups, and were continuously administered for 8 weeks by oral gavage with copper sulfate at a dose of 0, 25, 100, and 150 mg/kg/day, respectively. We determined the content of serum and testicular copper, testicular coefficient, testicular histopathology, sperm count and motility, the mRNA and protein levels of Caspase-3, Bax, and Bcl-2, Leydig cell count, testosterone content, testosterone synthetase, and testosterone synthesis–related genes. The results showed that the copper levels in serum increased in a dose-dependent manner, and the copper levels in testes were significantly related to serum copper levels. Male mice given copper sulfate 100 and 150 dosage groups showed significant decreased in sperm motility and sperm number as well as increased in testes damage, and there was no significant change in testicular coefficient in the four groups. The mRNA levels of Bcl-2 decreased and Caspase-3 increased in 150 dosage group, and Bax increased in two higher dosage groups. Meanwhile, Caspase-3 and Bax proteins increased in 150 dosage group, and Bcl-2 protein decreased in three copper treatment groups. Nevertheless, there were no differences on the levels of testosterone content and testosterone synthetase of 3β-HSD, 17β-HSD, 17α-Hyd, and 20α-Hyd, mRNA levels of Cyp11a1, Cyp17a1, and Star, and quantity of Leydig cells in four groups. Overall, these data showed that chronic copper exposure led to copper residues in the testes, and the doses of 100 and 150 mg/kg/day copper sulfate may induce hypospermatogenesis by increasing apoptosis without affecting testosterone secretion. [ABSTRACT FROM AUTHOR]

One-dimensional (1-D) antimony-doped tin oxide nanofibers (ATO NF) were synthesized with the electrospinning method and were employed as Pt catalyst support materials for the methanol oxidation reaction (MOR). Scanning and transmission electron microscopy (SEM/TEM) indicate that the ATO NF exhibits a porous nanofiber structure and the diameters are in the range of 100 to 150 nm consisting of the stacked small ATO nanoparticles. Uniformly dispersed Pt nanoparticles were then deposited onto the ATO NF and the synthesized ATO nanoparticles (ATO NP) with a Pt loading of 20 wt%. Compared with the commercial Pt/C catalysts, both the ATO NF– and ATO NP–supported catalysts showed slightly lower electrochemical surface areas (ECSA) and catalytic activity towards the MOR. However, ATO NF, when used as Pt support, showed enhanced MOR stability. This enhancement is mainly attributed to the greater corrosion resistance and porous nanofiber nature of the ATO NF, which tend to inhibit the aggregation of anchored Pt nanoparticles and reduce the loss of ECSA during the accelerated life test. XPS results also indicate strong interactions between platinum and ATO particles, which in turn significantly enhance stability towards MOR. [ABSTRACT FROM AUTHOR]

It is often difficult to guarantee the service life of fabric-based superhydrophobic materials that possess self-cleaning and oil–water separation capabilities. To extend practical use, a robust, self-healing superhydrophobic and superoleophilic cotton fabric was successfully prepared by simple impregnation and UV irradiation. The obtained superhydrophobic cotton had a contact angle of 152.4°. The as-prepared fabric showed excellent stability and remained superhydrophobic when soaked in corrosive liquids. Moreover, the prepared fabric can be used as an absorbent to separate the small amount of oil from the oil–water mixture and could be an oil/water separator by a simple device with the separation efficiency over 96%. More importantly, after 200 cycles of severe abrasion, the as-prepared fabric can retain superhydrophobicity and exhibit excellent self-healing property by simple heating treatment. With high oil–water separation efficiency and strong stability, the fabric prepared by this environmental-friendly method may contribute to the development of durable superhydrophobic materials. [ABSTRACT FROM AUTHOR]