Separation and extraction of bridge dynamic strain data (in Chinese)

Through comparing the measured data of dynamic strains due to loading and temperature by the strain gauge and temperature sensor at the same location, the information in the strain data was divided into three parts in the frequency domain by using the defined index named PSD (power spectra density)- ratio. The three parts are dominated respectively by temperature varying, stresses and noises and can be distinguished from the determined values of the separatirix frequencies. Then a simple algorithm was developed to separate the three types of information, and to extract the strain caused mainly by structural stresses. As an application of the proposed method, the influence of strain deformation and noises. As an application of the proposed method, the influence of strain deformation and noises on the fatigue assessment was investigated based on the separated data. The results show that, the determined values of separatrix frequencies are valuable for the monitoring data from other bridges. The algorithm is a multi resolution and hierarchical method, which has been validated as a simple and effective method for data analyses, and is suitable for the compression and pre-processing of the great amount monitoring data and easy to be integrated in the SHM's (structural health monitoring)software system. The strain due to temperature varying attributes only a little to the errors of fatigue assessment. However, the noises or random disturbance existed in the monitoring data have much responsibility for the errors, the main reason is that the random disturbance shifts the real strain/stress amplitude picked up by real structural stress or strain

Order parameter and current-phase relation in Josephson junctions composed of g+s-wave superconductors

Based on the analyses of bulk sensitive experimental data on penetration depths, Raman spectra, electron photoemission spectra, etc., G. M. Zhao concluded in a recent paper [Phys. Rev. B 64, 024503 (2001)] that the symmetry of high-Tc superconductors belongs to the g+s-wave type. To explore the common and uncommon features of the g+s-wave pairing state with respect to the d-wave pairing state, both superconductor-insulator-superconductor junction and superconductor-normal metal-superconductor junction have been studied self-consistently in this paper using the quasiclassical theory. The current phase relation for g+s-wave superconductors Δ(s,θ)=Δ0(s+cos 4θ) is investigated systematically as functions of s-wave component, crystal orientation angle β, as well as roughness ρ of the interface layer. Our results show that there exists a critical βC for a given s and ρ so that the current phase relation approaches asymptotically to I(φ)=ICsin(2φ) from I(φ)=ICsin(φ) as β→βC. The order parameter and βC-s relation are calculated self-consistently as interface roughness varies. Our results are compared with their counterparts in Josephson junctions with the d-wave pairing state obtained using a similar method.published_or_final_versio

SEARCHING FOR DEBRIS DISKS AROUND SEVEN RADIO PULSARS

We report on our searches for debris disks around seven relatively nearby radio pulsars, which are isolated sources that were carefully selected as targets on the basis of our deep Ks-band imaging survey. The Ks images obtained with the 6.5m Baade Magellan Telescope at Las Campanas Observatory are analyzed together with the Spitzer/IRAC images at 4.5 and 8.0μm and the WISE images at 3.4, 4.6, 12, and 22μm. No infrared counterparts of these pulsars are found, with flux upper limits of ∼μJy at near-infrared (λ < 10μm) and ∼10–1000μJy at mid-infrared wavelengths (λ > 10 μm). The results of this search are discussed in terms of the efficiency of converting the pulsar spin-down energy to thermal energy and X-ray heating of debris disks, with a comparison made of the two magnetars 4U 0142+61 and 1E 2259+586, which are suggested to harbor a debris disk.published_or_final_versio

A Novel Eigenvalue Algorithm for the Complex Band Structure and Eigenmodes of Plasmonic Crystals

published_or_final_versio

Sign reversal of the mixed-state Hall resistivity in type-II superconductors

Taking into account pinning, thermal fluctuations, and vortex-vortex interactions, we develop a unified theory to explain the sign reversal of the mixed-state Hall resistivity ρ xy in both high-T c and low-T c superconductors. Molecular dynamics simulations show that besides the pinning forces, either the thermal fluctuations in the high-T c superconductors or the vortex-vortex interactions in the low-T c ones play an important role in the sign reversal of ρ xy. From a calculated phase diagram for vortex motion, we find that the abnormal Hall effect always occurs in the plastic flow state of vortices. ©1999 The American Physical Society.published_or_final_versio

The thermal analysis of cutting/grinding processes by meshless finite block method

© 2018 Elsevier Ltd Development of the Finite Block Method (FBM) is presented, with the introduction of infinite elements for the first time, for predicting stationary and transient heat conduction in cutting/grinding processes. Utilizing the Lagrange series the first order partial differential matrix is derived, adopting a mapping technique, followed by the construction of the higher order derivative matrix. For linear stationary heat conductivity three free parameters including the velocity of the workpiece, the cooling coefficient and the inclined angle of the contact zone, together with their effects on temperature, are observed. For the transient heat conduction study, the Laplace transformation method and Durbin's inverse technique are employed. Numerical solutions are discussed and comparisons made with the finite element method and analytical solutions, demonstrating the accuracy and convergence of the finite block method

Excitonic quantum confinement modified optical conductivity of monolayer and few-layered MoS2

2016-2017 > Academic research: refereed > Publication in refereed journal201804_a bcmaVersion of RecordPublishe

Advance Directive and End-of-Life Care Preferences Among Nursing Home Residents in Wuhan, China: A Cross-Sectional Study

© 2014 AMDA - The Society for Post-Acute and Long-Term Care Medicine. Objectives: To describe Chinese nursing home residents' knowledge of advance directive (AD) and end-of-life care preferences and to explore the predictors of their preference for AD. Design: Population-based cross-sectional survey. Settings: Nursing homes (n= 31) in Wuhan, Mainland Southern China. Participants: Cognitively intact nursing home residents (n= 467) older than 60 years. Measures: Face-to-face questionnaire interviews were used to collect information on demographics, chronic diseases, life-sustaining treatment, AD, and other end-of-life care preferences. Results: Most (95.3%) had never heard of AD, and fewer than one-third (31.5%) preferred to make an AD. More than half (52.5%) would receive life-sustaining treatment if they sustained a life-threatening condition. Fewer than one-half (43.3%) chose doctors as the surrogate decision maker about life-sustaining treatment, whereas most (78.8%) nominated their eldest son or daughter as their proxy. More than half (58.2%) wanted to live and die in their present nursing homes. The significant independent predictors of AD preference included having heard of AD before (odds ratio [OR] 9.323), having definite answers of receiving (OR 3.433) or rejecting (OR 2.530) life-sustaining treatment, and higher Cumulative Illness Rating Scale score (OR 1.098). Conclusions: Most nursing home residents did not know about AD, and nearly one-third showed positive attitudes toward it. AD should be promoted in mainland China. Education of residents, the proxy decision maker, and nursing home staff on AD is very important. Necessary policy support, legislation, or practice guidelines about AD should be made with flexibility to respect nursing home residents' rights in mainland China

Threshold-voltage instability of polymer thin-film transistor under gate-bias and drain-bias stresses

Polymer thin-film transistors (PTFTs) based on MEH-PPV semiconductor are fabricated by spin-coating process and characterized. Gate-bias and drain-bias stress effects at room temperature are observed in the devices. The saturation current decreases and the threshold voltage shifts toward negative direction upon the gate-bias stress. However, the saturation current increases and the threshold voltage shifts toward positive direction upon the drain-bias stress. For variable bias stress conditions, carrier mobility is almost unchanged. The results suggest that the origin of threshold-voltage shift upon negative gate-bias stress is predominantly associated with holes trapped within the SiO 2 gate dielectric or at the SiO 2/Si interface due to hotcarrier emission under high gate-bias stress, while time-dependent charge trapping into the deep trap states in the channel region is responsible for the drain-bias stress effect in the PTFTs. © 2008 IEEE.published_or_final_versio