Dynamic Reliability Assessment of Heavy Vehicle Crossing a Prototype Bridge Deck by Using Simulation Technology and Health Monitoring Data

Overloads of vehicle may cause damage to bridge structures, and how to assess the safety influence of heavy vehicles crossing the prototype bridge is one of the challenges. In this report, using a large amount of monitored data collected from the structural health monitoring system (SHMS) in service of the prototype bridge, of which the bridge type is large-span continuous rigid frame bridge, and adopting FEM simulation technique, we suggested a dynamic reliability assessment method in the report to assess the safety impact of heavy vehicles on the prototype bridge during operation. In the first place, by using the health monitored strain data, of which the selected monitored data time range is before the opening of traffic, the quasi dynamic reliability around the embedded sensor with no traffic load effects is obtained; then, with FEM technology, the FEM simulation model of one main span of the prototype bridge is built by using ANSYS software and then the dynamic reliability when the heavy vehicles crossing the prototype bridge corresponding to the middle-span web plate is comprehensively analyzed and discussed. At last, assuming that the main beam stress state change is in the stage of approximately linear elasticity under heavy vehicle loads impact, the authors got the impact level of heavy vehicles effects on the dynamic reliability of the prototype bridge. Based on a large number of field measured data, the dynamic reliability value calculated by our proposed methodology is more accurate. The method suggested in the paper can do good for not only the traffic management but also the damage analysis of bridges

Maintenance Management Research of a Large-span Continuous Rigid Frame Bridge Based on Reliability Assessment by Using Strain Monitored Data

When the bridge components needing maintenance are the world problem at present, and the health monitoring system is considered to be a very helpful tool for solving this problem. In this paper, a large number of strain data acquired from the structural health monitoring system (SHMS) installed on a continuous rigid frame bridge are adopted to do reliability assessment. Firstly, a calculation method of punctiform time-dependent reliability is proposed based on the basic reliability theory, and introduced how to calculate reliability of the bridge by using the stress data transformed from the strain data. Secondly, combined with “Three Sigma” principle and the basic pressure safety reserve requirement, the critical load effects distribution function of the bridge is defined, and then the maintenance reliability threshold for controlling the unfavorable load state which appears in the early operation stage of this type bridge is suggested, and then the combination of bridge maintenance management and health monitoring system is realized. Finally, the transformed stress distribution certifies that the load effects of concrete bridges practically have a normal distribution; as for the concrete continuous rigid frame bridge with C50 strength grade concrete, the retrofit reliability threshold should be valued at 6.13. The methodology suggested in this article can help bridge engineers do effective maintenance of bridges, which can effectively extend the service life of the bridge and bring better economic and social benefits

Nonlinear magnetotransport shaped by Fermi surface topology and convexity in WTe2

The nature of Fermi surface defines the physical properties of conductors and many physical phenomena can be traced to its shape. Although the recent discovery of a current-dependent nonlinear magnetoresistance in spin-polarized non-magnetic materials has attracted considerable attention in spintronics, correlations between this phenomenon and the underlying fermiology remain unexplored. Here, we report the observation of nonlinear magnetoresistance at room temperature in a semimetal WTe2, with an interesting temperature-driven inversion. Theoretical calculations reproduce the nonlinear transport measurements and allow us to attribute the inversion to temperature-induced changes in Fermi surface convexity. We also report a large anisotropy of nonlinear magnetoresistance in WTe2, due to its low symmetry of Fermi surfaces. The good agreement between experiments and theoretical modeling reveals the critical role of Fermi surface topology and convexity on the nonlinear magneto-response. These results lay a new path to explore ramifications of distinct fermiology for nonlinear transport in condensed-matter

Multi-hot spot configuration on urchin-like Ag nanoparticle/ZnO hollow nanosphere arrays for highly sensitive SERS

MOST of China under the 973 programs [2009CB930704]; National Natural Science Foundation of China [61106118]; Science and Technology Project of Fujian Province of China [2013H0046]; Natural Science Foundation of Fujian Province of China [2011J01362]; Fundamental Research Funds for the Central Universities [2011121026]Urchin-like Ag nanoparticle (NP)/ZnO hollow nanosphere (HNS) arrays were fabricated employing a simple, low cost and wafer scale method consisting of nanosphere lithography (NSL) and solution processes. This three-dimensional (3D) multi-hot spot decorated nanocomposite presents an as high as 108 Raman enhancement using Rhodamine 6G (R6G) as the probe with the concentration down to 10(-10) M. The high density hot spots in a unit area and strong field intensity around each individual hot spot in 3D layout are believed to be the major reasons for this high sensitivity Raman phenomenon, which is further proved by the theoretical simulation results. Given its high Raman sensitivity and good reproducibility in a large area, this urchin-like Ag NP/ZnO HNS hybrid nanoarray can be reasonably proposed to be used as a SERS substrate in practical applications, including bio-sensing, materials characterization, environmental science and so on

Band edge emission enhancement by quadrupole surface plasmon-exciton coupling using direct-contact Ag/ZnO nanospheres

Periodic Ag nanoball (NB) arrays on ZnO hollow nanosphere (HNS) supporting structures were fabricated in a large area by a laser irradiation method. The optimized laser power and spherical supporting structure of ZnO with a certain size and separation were employed to aggregate a sputtering-deposited Ag nano-film into an ordered, large-area, and two dimensional Ag NB array. A significant band edge (BE) emission enhancement of ZnO HNSs was achieved on this Ag NB/ZnO HNS hybrid structure and the mechanism was revealed by further experimental and theoretical analyses. With successfully fabricating the direct-contact structure of a Ag NB on the top of each ZnO HNS, the highly localized quadrupole mode surface plasmon resonance (SPR), realized on the metal NBs in the ultraviolet region, can effectively improve the BE emission of ZnO through strong coupling with the excitons of ZnO. Compared with the dipole mode SPR, the quadrupole mode SPR is insensitive to the metal nanoparticle's size and has a resonance frequency in the BE region of the wide band gap materials, hence, it can be potentially applied in related optoelectronic devices

Plasmonic-enhanced self-cleaning activity on asymmetric Ag/ZnO surface-enhanced Raman scattering substrates under UV and visible light irradiation

Two different asymmetric Ag/ZnO composite nanoarrays were fabricated. These nanoarrays are proposed as highly sensitive and uniform surface-enhanced Raman scattering (SERS) substrates with plasmonic-enhanced UV-visible photocatalytic properties for self-cleaning. The asymmetric nanostructures are composed of Ag nanoparticles hanging inside or capping on the top of ZnO hollow nanospheres, which allows the generation of a strong local electric field near the contact area owing to the asymmetric dielectric environment. Experimental and simulation results showed that these asymmetric structures are favorable for achieving high photocatalytic activity under UV and visible light irradiation, in addition to improving the SERS performance. The electron transfer model based on band gap alignment was employed to further illustrate the mechanisms of the photocatalytic activity, which was dependent on the wavelength of the irradiation. Given the dramatically improved photocatalytic performance, together with the reproducible and uniform SERS signals verified by the Raman mapping results, the large area ordered asymmetric metal/semiconductor nanoarrays have been demonstrated to be suitable for further applications in multifunctional photoelectrochemical chips. This journal is ? the Partner Organisations 2014

Enhanced reversible lithium storage in germanium nano-island coated 3D hexagonal bottle-like Si nanorod arrays

MOST of China [2009CB930704]; National Natural Science Foundation of China [61106118]; Science and Technology Project of Fujian Province of China [2013H0046]; Natural Science Foundation of Fujian Province of China [2011J01362]; Fundamental Research Funds for the Central Universities [2011121026]The rapid development of numerous microscale electronic devices, such as smart dust, micro or nano bio-sensors, medical implants and so on, has induced an urgent demand for integratable micro or nano battery supplies with high energy and power densities. In this work, 3D hexagonal bottle-like Si/Ge composite nanorod (NR) array electrodes with good uniformity and mechanical stability potentially used in micro or nano rechargeable Li-ion batteries (LIBs) were fabricated on Si substrates by a cost-effective, wafer scale and Si-compatible process. The optimized Ge nano-islands coated Si NR composite arrays as anode materials exhibit superior areal capacities and cycling performances by virtue of their favourable structural and improved conductivity features. The unique Si-based composite electrode in nanostructures can be technically and fundamentally employed to configurate all-solid-state Li-ion micro-batteries as on-chip power systems integrated into micro-electronic devices such as M/NEMS devices or autonomous wireless microsystems

Distribution of high-risk HPV types among women in Sichuan province, China: a cross-sectional study

Abstract Background Persistent infection with high-risk human papillomavirus (HR-HPV) is a major cause of cervical intraepithelial neoplasia and invasive cervical cancer. We investigated the prevalence of HR-HPV infection and distribution of viral genotypes among women in this area. Methods Women in Sichuan older than 20 years were screened for cervical cancer between January 2015 and December 2016 using liquid-based cytology testing and a flow cytometry-fluorescence hybridization test for HPV-DNA. Frequency tables were evaluated using the chi-squared test (χ2). Results Of the 17,319 women aged 20–85 years who participated in the study, Overall prevalence of HR-HPV infection was 12.6% (2178/17,319). The most prevalent viral type was HPV-52, which was present in 2.5% of individuals, followed by HPV-53 (1.6%), HPV-58 (1.5%), HPV-16 (1.1%), HPV-56 (0.9%), HPV-39 (0.8%). In HSIL, the five most common HR-HPV types were HPV52, 16, 58, 33 and 56. HPV16/18 in HSIL only makes up 25.9% of HSIL, whereas HPV31/33/45/52/58 make up 56.8%. Overall HR-HPV prevalence among women older than 65 years was 15.2%, significantly higher than the prevalence in other age groups (P < 0.05). Infection with dual or multiple HR-HPV types was associated with greater risk of abnormal cytology. Conclusion Overall HR-HPV prevalence in Sichuan is as high as in large cities in China. The HR-HPV types 52, 16, 58, 33 and 56 predominated in this sample of HSIL women primarily from the banking and public sector in Sichuan. High prevalence among women older than 65 years needed pay attention to